Band 8, Heft 1

Rapid, effective separation of phases is an essential step in many hydrocarbon conversion gas-solid processes. In heavy oil upgrading, fluid catalytic cracking (FCC) and biomass pyrolysis, for example, very fast separation of reacting gases from catalytic or heat-bearing solids is required to inhibit further reaction. The primary functions of a rapid separator in the context of a gas-solid flow are, first, to terminate contact between the reacting gases and the catalytic or hot solid particles and, second, to recover the isolated product vapors. Uninterrupted vapor-solid contact results in degraded, overcracked and generally less valuable products. Increasing interest in rapid separation has led in the past 25 years to a wide variety of proposed separator designs in the literature.Centrifugal separation is the fundamental principle underlying cyclone operation and most rapid gas-solid separation processes. Traditional cyclones rely on centrifugal separation and are very widely applicable. They are used for the removal of solid particulate matter from gas or liquid streams, for gas demisting, and in hydrocyclones. Most FCC processes employ traditional cyclone configurations for secondary and tertiary separation. The review briefly summarizes important topics studied in reverse flow cyclone operation. For initial separation, however, most fast gas-solid separators in the literature feature only partial cyclone layouts. Separation typically occurs more quickly in these devices relative to traditional cyclones, likely at the expense of separation efficiency.The current review places emphasis on experimental results and novel separation techniques in the context of fast gas-solid separation. Several recent methods of rapid gas-solid separation employ co-current or "uniflow" centrifugal arrangements. Hence, particular attention is directed to co-current centrifugal separators. These devices have been studied much less intensively than their reverse flow counterparts. Fast co-current separators, with their novel, partial cyclone layouts, are interesting for their performance characteristics in relation to popular commercial designs.

A review of recent advancements in the combination of ultrasonolysis with other advanced oxidation processes is studied. This study is based on the recent achievements and developments in the field of water and wastewater treatment using ultrasonic irradiation by means of acoustic cavitation with other advanced oxidation technologies. The most important parameter in combined methods is the synergetic effect which is a variable relative to the type of contaminant(s) and other physicochemical properties. The synergetic effect has the key role in process intensification so that a higher synergetic effect provides a higher intensified process efficiency. Results showed that sonolysis is a method that can increase the synergetic percentage in lowering fixed and even operating cost of the wastewater remediation. The combination of photolysis, photocatalysis, Fenton, photo-Fenton, and ozonation processes with ultrasonolysis results in hydroxyl radical production and therefore, the degradation of the organic chemicals. The effect of various parameters on the efficiency of combined processes is investigated in the present study. The combined process performance and the synergetic effect depend on the operating conditions and wastewater characteristics. The synergetic effect can enhance the degradation of organic compounds up to 400%. For example, it has been proven that the sonophotocatalytic process shows over 80% improvement with respect to the photocatalysis alone.

Available data and correlations for non ideal flow in liquid-solid fixed beds are summarized and reviewed with focus on irregular-shaped particles as packing material. The reason is that in many industrial applications (adsorption, ion exchange, catalysis, etc.) the particles used are of irregular shape while the vast majority of available data on dispersion and non ideal flow is on non-porous spherical or other ordered-shaped particles (saddles, rings, cylinders, tablets, etc.). In the same time, dispersion plays an important part, for example, in reactant and product transport in packed bed reactors, in adsorption, leaching, etc. In the present review all available correlations and data for liquid-solid fixed beds packed with irregular-shaped particles are collected for the prediction of the dispersion coefficients over a wide range of practical values particle Reynolds number. For the current review, 198 experimental points used and 6 Ped – Rep correlations are presented, all derived for irregular-shaped particles.

The world’s progression towards the Hydrogen economy is facilitating the production of hydrogen from various resources. In the carbon based hydrogen production, Water gas shift reaction is the intermediate step used for hydrogen enrichment and CO reduction in the synthesis gas. This paper makes a critical review of the developments in the modeling approaches of the reaction for use in designing and simulating the water gas shift reactor. Considering the fact that the rate of the reaction is dependent on various parameters including the composition of the catalyst, the active surface and structure of the catalyst, the size of the catalyst, age of the catalyst, its operating temperature and pressure and the composition of the gases, it is difficult to narrow down the expression for the shift reaction. With different authors conducting experiments still to validate the kinetic expressions for the shift reaction, continuous research on different composition and new catalysts are also reported periodically. Moreover the commercial catalyst manufacturers seldom provide information on the catalyst. This makes the task of designers difficult to model the shift reaction. This review provides a consolidated listing of the various important kinetic expressions published for both the high temperature and the low temperature water gas shift reaction along with the details of the catalysts and the operating conditions at which they have been validated.

The objective of this paper is to give a critical survey of the present status within the field of control of a reactive distillation column. Control of a reactive distillation column is a challenging task due to process nonlinearity and complex interactions between the vapor-liquid equilibrium and chemical reactions. There are different types of control methodologies, which have been studied in the reactive distillation, ranging from a simple proportional-integral (PI) controller to advanced model predictive controllers (MPC) such as dynamic matrix control (DMC), quadratic dynamic matrix control (QDMC), robust multivariable predictive control technology (RMPCT), generalized predictive control (GPC), and other advanced control techniques. With the goals of optimal performance, energy conservation and cost effectiveness of process operations in industries, the design of optimal controllers and controller performance assessment have received great attention in both industries and academia. The main objective of control is to maintain the product purity within the desired range.

This work aims at compiling the important works on the modeling of a fluid catalytic cracking (FCC) riser reactor. The modeling of a riser reactor is very complex due to complex hydrodynamics and unknown multiple reactions, coupled with mass transfer resistance, heat transfer resistance and deactivation kinetics. A complete model of the riser reactor should include all the important physical phenomena and detailed reaction kinetics. As the computational fluid dynamics (CFD) is emerging as a powerful tool for modeling the FCC riser, various works on riser modeling using CFD are also included in the paper.

A 6-lump kinetic model, including a catalyst decay function for hydrocracking of vacuum gas oil in a commercial plant, is proposed. The model considers vacuum gas oil (VGO) and unconverted oil, having boiling point higher than 380-°C (380+°C) as one lump. Other lumps are diesel (260-380-°C), kerosene (150-260-°C), heavy naphtha (90-150-°C), light naphtha (40-90-°C) and gases (40-°C) as products. Initially, a kinetic network with thirty coefficients is considered, but following an evaluation using measured data and order of magnitude analysis, mainly the route passes of converting middle distillates to naphtha lumps are omitted; thus the number of kinetic coefficients is reduced to eighteen. This result is consistent with the reported characteristics of amorphous catalyst, which has the tendency to produce more distillates than naphtha. By using catalyst decay function in the kinetic model and replacing days on stream with a noble term, called accumulated feed, the prediction of the final approach during 1.5 years is in good agreement with the actual commercial data. The average absolute deviation (AAD%) of the model is less than 5% for all main products. If the residue or unconverted VGO is considered, the error only increases to 6.94% which is still acceptable for a commercial model. The results also confirm that the hydrocracking of VGO to upgraded products is represented better by a second order reaction.

In this work the observability properties for a class of nonlinear systems is presented, by considering linear, geometric and algebraic approaches. The observability conditions for state variables, unstructured uncertainties and detectable states are considered for a class of nonlinear systems related with several (bio)-chemical reacting processes. The considered examples are related with (bio)-chemical continuous reactors and a metabolic model, where their observability properties are analyzed. A comparison of the corresponding results is done, showing the suitability of each approach.

This study is motivated by a growing popularity of artificial neural network for process modeling and regression problems. However, many ANN regression application studies are performed by ‘expert' users who have a good understanding of ANN methodology. Since the quality of ANN models depends on a proper setting of ANN architecture and ANN meta-parameters, the main issue for practitioners trying to apply ANN regression is how to set these parameter values (to ensure good generalization performance) for a given data set. Non-expert users face a difficulty in finding an optimum ANN architecture and are often confused about how to choose the ANN meta parameters. The present paper addresses this issue and develops a new hybrid procedure to find the optimum ANN architecture and tunes the ANN parameters, thus relieving the ‘non expert' users. This method incorporates hybrid artificial neural network and differential evolution technique (ANN-DE) for efficient tuning of ANN meta parameters. The algorithm has been applied for modeling of a commercial ethylene oxide (EO) reactor. The model developed through this hybrid algorithm can predict the EO reactor output with only 0.4% error.

A study of direct hydration of dihydromyrcene (DHM) with H2O to produce dihydromyrcenol (DHMOH) has been carried out using cation exchange resins as catalysts in a batch stirred-tank reactor. The effect of different parameters such as agitating speed, catalyst type, catalyst loading, molar ratio of the reactants and solvent, temperature and solvent on the conversion of DHM were investigated to obtain the optimal conditions of the reaction. The kinetics of hydration process was studied in the temperature range from 333.15 K to 353.15 K. A pseudo-homogeneous kinetics model was used to explain the reaction rate and the reaction rate constants and the reaction activation energy were determined.

A comprehensive mathematical model for the ethylene/1-butene polymerization in solution with Ziegler-Natta catalyst is developed. The process comprises a series of continuously stirred and tubular reactors in which polyethylene resins with different properties may be produced. The mechanistic model considers the moments of the bivariant molecular weight distribution in order to ascertain the average molecular weight and polydispersity. The polymer quality is verified through the melt index, density and stress exponent, which is a measure of the polydispersity. The model developed investigates the stationary and dynamic behavior of the process following step changes in feed conditions. It allows for the prediction of non-linear and inverse responses, encouraging the use of the model for optimization and control purposes.

Nowadays, with the worldwide, increasing demands of the high qualitative gasoline, it is necessary to establish new naphtha reforming units and develop the traditional units to the high efficiency processes. In this work, according to the recent progresses in naphtha reforming technology, a mathematical modeling of a continuous catalytic reformer with catalyst recirculation is developed for simulation and optimization of the new industrial continuous reformers. The process model uses an extended version of the kinetic model reported by Padmavathi, with some modifications on kinetic constants, and it considers the deactivation rate of the catalyst and pressure drop within the reactor. The process model is based on a 12-lumped kinetics reaction network and has been proved to be quite effective in terms of an industrial application. The naphtha is based on 25-lumped pseudocomponents (including C6 to C10 hydrocarbons) in three categories of n-paraffins, isoparaffins, naphthens, including cyclopentanes and cyclohexanes, and aromatics. The light hydrocarbons product, consisting of C1 to C5 n-paraffins, is taken into account as the products of hydrocracking reaction. First, the kinetic parameters of the reactions are tuned using real results of the outlet temperatures and components in industrial operating conditions. At the next stage, validation of the model was carried out using a new naphtha feed in industrial scale. The final stage of this research was based on splitting a naphtha feed using its only ASTM boiling point and specific gravity, to converting to the components and applying into the process model to predict the outlet temperature and composition, the reformate yield and RON, hydrogen and LPG product, and coke formation at each cycle. The predicted and commercially reported results agreed with each other.

Cell growth and recombinant phytase production under the control of the GAP promoter were studied in continuous cultivation experiments of Pichia pastoris. Based on these studies, a simple kinetic model was established to predict biomass and enzyme production. Although parameters were mainly estimated using the results of continuous cultivation, the proposed model was able to successfully predict cell growth and phytase production in three different fed-batch cultivations of P. pastoris using limited glucose feeding.

The coking process includes two dynamic and isothermal steps. In this process, some factors control the coke formation kinetics. In this research, effects of some important and effective parameters of feed on the quality of petroleum coke were studied. Two hydrocarbon residue feeds; Cracked Fuel Oil (CFO) and Styrene Monomer Tar (SMTAR) were used at 500°C with atmospheric pressure of nitrogen used as an inert gas. Rate of weight loss and gas evolution from these feeds were considered by data of thermal analysis TG (thermogravimetry) and DTG (derivative thermogravimetry). Based on the results, CFO was assigned as the better feed. After selecting better feed, simultaneous thermogravimetry-differential analysis (TG-DTA) was used to study the pyrolysis kinetics of CFO. Samples were heated in a TG-DTA apparatus in nitrogen atmosphere at a temperature range of 37-600°C. The activation energy (Ea) and pre-exponential factor (A) were calculated from the experimental results by using a three stage Arrhenius-type kinetic model and showed that CFO pyrolysis kinetics at temperature ranges 37-285, 320-450 and 467-600°C follows first, second and first order kinetics, respectively. Attentive to temperature increase and reaction progress, activation energy and pre-exponential factor indicated different values at each stage. Also, kinetics of the isothermal step of coke formation was studied during heating of CFO. Samples were reacted in a tube furnace at 450°C and with nitrogen atmosphere. The kinetics of coke formation for petroleum residue was followed by solvent extraction (insolubility in hexane (HI), toluene (TI)) and a development of TI approximate to apparent first order kinetics. The rate constant at this temperature was calculated and it was also observed that the coke formation had been started at a temperature below 450°C.

Global gas hold-up and volumetric oxygen transfer coefficient (kLa) were evaluated in three internal-loop airlift reactors (ALR) with different working volumes (2, 5, and 10 dm3) and similar geometric configuration utilizing eight Newtonian fluids. Superficial gas velocity in the riser (UGR) was ranged from 0 to 0.112 ms-1. The effects of the superficial gas velocity (UGR) and liquid viscosity had contrary effects on kLa. However, they presented the same order of magnitude showing that the viscosity effect on the oxygen mass transfer cannot be neglected. Two correlations based on dimensional analysis relating global gas hold-up and kLa to the geometric parameters, physical properties of the fluids, and operational conditions were proposed. Very good fittings between calculated and experimental data of and kLa were obtained. The influence of the internal diameter of the reactor on kLa was considered positive showing that in large-scale reactors an appropriate oxygen transfer can be reached under smaller aeration conditions, due to higher internal diameter.

Effective water management is one of the key strategies for improving the performance and durability of PEM fuel cells. Phenomena such as membrane dehydration, catalyst layer flooding and two-phase flow in flow-channels are all determined by the distribution and movement of water during cell operation. In this study, gas-liquid flow in mini-channels relevant to fuel cells was numerically studied using a CFD two-phase flow model in combination with a volume of fluid (VOF) method. The results show that the surface wettability of the channel wall can greatly affect the flow pattern, especially when the channel walls and the gas diffusion layer (GDL) surface possess different contact angles. When the channel walls are more hydrophobic, more water is accumulated on the GDL. An increase in the surface tension results in a slight increase of slug frequency and a slight decrease in slug length. The onset of slugging along the channel is determined by the gas-liquid mixture velocity, gas-to-liquid flow ratio and the way water is introduced into the gas flow channel. Furthermore, the calculated pressure drop fluctuations show a strong dependence on the channel liquid content and the slug length.

This paper presents an investigation on the wall layer interactions in a lower-half heated, upper-half cooled rectangular enclosure in both steady and unsteady laminar flow regimes. Results show that the flows have four wall layers and center core regions. At low Rayleigh numbers, both the wall layers and cores are steady. Each of the streams in the core region is formed by the combination of two wall layer segments from the same half of the enclosure. Fluid exchange between the two halves is very efficient. At high Rayleigh numbers, the wall layers at the same side of the enclosure collide head-on and generate unsteady streams. The interaction between the streams establishes a strong mixing region at the median height, which homogenizes the fluid temperature in the core regions. The overall flow structure and the path of the heat flow in the enclosure are determined by the momentum strength of the wall layers and their interactions.

In this study, the etherification reaction of glycerol (G) with tert-butyl alcohol (TBA) was investigated for the production of high quality transportation fuel additives. The reaction was carried out in liquid phase, in a continuous flow reactor in the presence of various solid acid catalysts. Activities of acidic resin catalysts, such as Amberlyst-15 (A-15), Amberlyst-16 (A-16) and Amberlyst-35 (A-35), Nafion-SAC-13 and ?-alumina were compared. Significant increase in conversion was observed with an increase in temperature. Amberlyst 15 showed the highest activity at about 110°C, giving glycerol conversion values of about 0.5 at a space time of 18 g cm-3 s. However, A-16 gave higher di-ether selectivity values. Nafion-SAC-13 showed activity at higher temperatures, while the activity of ?-alumina was very low, even at 400°C.

In this paper, we present the approximate solutions of the time fractional chemical engineering equations by means of the variational iteration method (VIM) and homotopy perturbation method (HPM). The fractional derivatives are described in the Caputo sense. The solutions of the chemical reactor, reaction, and concentration equations are calculated in the form of convergent series with easily computable components. We compared the HPM against the VIM; an additional comparison will be made against the conventional numerical method. The results show that HPM is more promising, convenient, and efficient than VIM.

The secondary structure of the toxin from Bacillus thuringiensis (Bt) is directly correlated with the insecticidal activity and persistence. The conformational changes of Bt toxin before adsorption and after contact with, or adsorbed from, red soil and brown soil were characterized using circular dichroism (CD) and fluorescence spectroscopy. The toxin of Bt contacted with soils for 2 h, the content of ?-helix increased 14.1%-19.0%, and ?-sheet increased 5.1%-5.8%, but the content of the non-regular coil decreased. There was a minor change bout the content of the ?-turns. The fluorescence intensity of contacted toxin decreased and retained 72.8%-93.7% of the intensity of native toxin. The blue-shifts (2.5-3.5 nm) of maximum emission wavelength were observed. The influential trend of desorption was in agreement with the contact course, the influential extent, however, the former was higher than the latter. The content of ?-helix of desorbed toxin increased 33.1%-33.8%, and ?-sheet increased 17.3%-26.8%. The fluorescence intensity retained 70.4%-91.4% and blue-shifts of 3.5 nm were observed.

We propose a general methodology to develop a hybrid neural model for a wide range of biotechnological processes. The hybrid neural modelling approach combines the flexibility of a neural network representation of unknown process kinetics with a global mass-balance based process description. The hybrid model is built in such a way that its trajectories keep their physical and biological meaning (mass balance, positivity of the concentrations, boundness, saturation or inhibition of kinetics) even far from the identification data conditions. We examine the constraints (a priori knowledge) that must be satisfied by the model and that provide additional conditions to be imposed on the neural network. We illustrate our approach with various biotechnological processes showing how to select the appropriate neural network architecture. The method is detailed for modelling an anaerobic wastewater treatment bioreactor using experimental data.

This paper presents the kinetics of catalytic thermolysis of the sugarcane molasses based alcohol distillery wastewater coming out from distillation unit (distillery wastewater or DWW) and the biodigester (biodigester effluent or BDE) having high biochemical and chemical oxygen demand (BOD and COD). The effluents were thermally pretreated at 80-100°C and atmospheric pressure in the presence of various catalysts. The homogeneous copper sulphate and the heterogeneous metal oxide catalysts, such as CuO, MnO2-CeO2 and ZnO were used for the catalytic thermolysis. The CuO catalyst was found to be best amongst all the catalysts, giving 47% COD reduction, 68% colour reduction for DWW and 61% COD reduction, 78% colour reduction for BDE at 100°C using 4 kg m-3 catalyst loading in 12h. The experimental data on the catalytic thermolysis exhibit two clearly distinct COD reduction phases: the first phase being fast followed by the second phase which is a slower. Both the phases of the catalytic thermolysis are found to follow first order COD reduction kinetics. Catalytic thermolysis with 3 kg m-3 CuO at 100°C and atmospheric pressure shows about 1.6 and 1.5 times higher COD reductions in comparison to that without using a catalyst for the DWW and BDE, respectively.

This paper presents an analysis of the gas holdup evolution in a novel type of jet-loop membrane bioreactor (JLMBR), designed for nitrogen removal through the nitrite route application. Its configuration is inspired from airlift systems. It consists of a 60-l reactor made of an internal airlift system coupled to an external liquid recirculation loop. Hollow fiber membranes are submerged in the riser compartment. The process was intermittently fed with a synthetic ammonia solution and the gas holdup evolution was monitored for 500 to 600 days. Experiments were performed using flowrates ranging from 0.4 to 1.03 Nm3/h, and from 0 to 0.6 m3/h for air and water, respectively. This corresponded to superficial velocities from 0.004 to 0.03 m.s-1 for air and 0 to 0.011 m.s-1 for water. The gas holdup ?g was directly measured by the volume expansion method, using a tubular level meter located on the plant. The reported results showed that, in the absence of microorganisms, ?g ranged between 0.5 and 5.5% for the investigated range of gas liquid superficial velocities, whilst increasing from 0.5 to 4.8% only in the presence of gas (no liquid recirculation). This double influence of the air and the liquid velocities on the gas holdup was described by a multilinear correlation.However in the presence of biosolids in the reactor, the gas holdup raised up to 6.5%, corresponding to an increase of ca. 48% (in average, with respect to data recorded on day 0). This increase in ?g was attributed to both a gas entrainment effect and an impact of the bioparticles recirculated into the reactor. Under experimental conditions investigated, the gas holdup increased linearly with the air and the liquid velocities, what corresponded to the bubbly flow regime in the system. This showed that, according to investigated conditions, the impact of circulated biomass was not enough to change the bubble gas flow regime.

Heat supplement is necessary for FCC gasoline upgrading processes to keep the heat balance of reaction-regeneration system, while excess heat would be removed in FCC process due to the processing of heavy feedstock. Combining gasoline upgrading processes with FCC process can realize the heat coupling so as to achieve the maximum energy utilization. In this paper, the heat balance calculations of a commercial FCC unit and a FCC gasoline aromatization process were carried out, and the feasibility as well as the way to accomplish the heat coupling for the two processes was investigated. The results showed that the coked aromatization catalysts could be heated to the desired temperature by the direct contact with the hot regenerated FCC catalysts. The pilot experiment and CFD simulation was carried out to investigate the flow behavior and heat transfer of the direct coupling system of FCC process and FCC gasoline aromatization process. The results indicated that the well-mixing and efficient heat transfer between FCC catalysts and aromatization catalysts, as well as the sufficient regeneration of aromatization catalysts, could be achieved at appropriate operating conditions.

A Modified Activated Sludge Model No.1 (M-ASM1), including six COD components (SI, SS, XI, XS, XH and SO) and three biochemical processes (aerobic growth of heterotrophs, aerobic decay of heterotrophs and hydrolysis of entrapped organics) is used to simulate the anaerobic hydrolysis-aeration- sedimentation treatment series in a full-scale textile dyeing wastewater treatment plant with an influent flowrate of 200,000 m3/d. M-ASM1 has the following characteristics: (1) the effect of temperature variation on biochemical reactions is included; (2) adding a parameter: ?. Using this parameter, the anaerobic hydrolysis tank and the aerobic initial compartments in which the dissolved oxygen concentrations are equal to "0 mg/L" can be differentiated; (3) the oxygen transfer coefficient KLa is excluded. Namely, as long as inputting the aeration flowrate, the pressure in the aeration pipe and other running data on air supply into this model, M-ASM1 can simulate the oxygen concentrations of each compartment in a plug-flow aeration tank.

A 2D model of a confined impinging jets mixer having the same geometry of the mixing chamber of a Reaction Injection Moulding, RIM, machine is introduced for the flow field simulation in a Computational Fluid Dynamics, CFD, code. From the CFD simulations the flow field structures and dynamics are clearly established. In addition, the numerical parameters affecting the 2D model simulations are studied, setting for each parameter a validity range. The 2D model is validated and used in the study of some operational parameters: the Reynolds number, the Froude number and the momentum ratio between the opposed jets. The validation of the CFD simulations is also made by comparison with experimental results. The limitations of the 2D model, for simulating the actual 3D flow field, are assessed; from the 2D/3D comparison, it is clearly shown that the introduced model can predict the main flow field features.

Gas liquid reactors are extensively used in many metallurgical processes involving the refining of liquid metals. In these processes, reactions leading to the oxidation of various solutes in liquid metal often compete with each other, which ultimately determine the liquid metal composition. In the present paper, a model has been proposed to simulate the evolution of solute contents in a metallic melt considering mass transfer of solutes in the melt in the vicinity of the bubble, equilibrium at the gas-metal interface and gas composition evolution in the bubble during its ascent through the melt. The composition of solutes at the metal-gas interface in principle can be altered by changing the injected gas composition.The model was applied to the case of oxygen injection through a lance into liquid steel-containing C and Cr, aiming sufficient decarburization without much oxidation of Cr to the slag. The Cr loss to the slag by oxidation is generally much more than that expected based on equilibrium thermodynamics applied to the bulk metal and gas. The actual Cr loss, as shown by the present model, is determined by the composition of solutes at the metal-gas interface rather than in the bulk. The effect of change of the partial pressure of oxygen in the bubble by replacing oxygen by carbon dioxide in the injected gas and the corresponding evolution of C and Cr contents in the melt was simulated. Some preliminary experiments were conducted to validate the model predictions. The frame work of the model is generic and can be extended to many gas-liquid metal reactors in liquid metal processing.

This research examines the transesterification reaction of soybean oil with methanol in order to model and simulate a non-ideal continuous stirred-tank reactor. A mathematical model has been developed for the reactor. The biodiesel production process was optimized by application of factorial design 25 and response surface methodology. Factorial design and response surface analysis were combined with modeling and simulation to determine the operating conditions that maximize biodiesel production and minimize reactor volume. The optimum results obtained were conversion (0.95), molar ratio alcohol/oil (6:1), temperature (60.5 oC), ? (0.75), bypass (0.10) and reactor volume (1,500 L).

This paper reports the results of reforming methane into synthesis gas using industrial Ni-Al2O3 catalyst (75% NiO wt.) and Ni-Al2O3 produced by the sol gel method (8% Ni wt.). A mathematical investigation on the performance of a one-dimensional model of catalytic conventional fixed-bed reactor was developed and implemented for the process. The results indicated that the industrial catalyst favored the water gas shift (WGS) reaction increasing CO2 production. However in temperatures of 773 and 973 K the yield (H2/CH4,reacted) was more efficient for the sol-gel catalyst. This result is possibly due to the different characteristics as specific surface area and temperature reduction. The model validation for the adjustment parameters U and a1 was more efficient for temperature profiles (2% error) than for mole fraction (10% error).

Effects of secondary air (SA) injection or air-staging on the gas-solids flow properties in the riser of a circulating fluidized bed (CFB) were investigated. The experiments were carried out in a CFB cold model with a square cross-section of 0.25m×0.25m and a height of 6.07m. The axial pressure drop profile along the riser was reported. And the local solids holdup profile at the centerline and the diagonal line of some cross sections which influenced by the SA injection was measured with an optical fiber probe. Two SA arrangement modes, i.e. four SA nozzles located on four walls (Wall SA) and four corners (Corner SA) were conducted. Air-staging results in a denser bottom bed for both two SA modes. The Wall SA case has a higher solids holdup than the Corner SA case in most regions of lower bed except the corner region but was leaner in the vicinity of SA injection level. W-shaped solids concentration profile was found in the region immediately above the SA injection level for Wall SA case but not obvious for Corner SA case. Fractal dimension was analyzed for pressure drop fluctuations and local solids concentration signal. Air-staging led to smaller fractal dimension value than the case without SA injection. The SA jets affected the local gas-solids distribution and fluctuation in the region close to the SA injection. Radial and axial solids transfer should be considered for the fractal analysis.

CFD (computational fluid dynamic) simulation that is based on finite volume method is used to study the light off performance of automotive catalytic converter. The flow distribution and the conversion efficiency of CO are achieved first, and the predictions are in good agreement with the experiment and finite difference method reported before. The present work investigates the effect of ceramic monolith wall thickness on the temporal variations of the radial solid temperature, mean solid temperature, axial flow temperature and CO conversion efficiencies in monolithic reactors during the light-off phase. It is found that the wall thickness can have a significant influence on the light off performance. When the monolith wall thickness is thinner, the light off performance of automotive catalytic converter is better. These studies help to understand better the performance of the catalytic converter in order to optimize the converter design.

A one-dimensional-isothermal model and an analytical solution for the mass transport (migration and diffusion) of protons in a single PEM fuel cell have been developed. Under a linear approximation between current density and electric potential (pseudo-primary current distribution) we have obtained the proton concentration profile along the cathodic and anodic gas diffusers as a function of the position. The graphical shape of the function allows us to discuss the effect of the physicochemical parameters in our model especially on the anodic side of the diffuser. From the dependence of the electric potential and current density with the position we have obtained a theoretical polarization curve. Under the pseudo-primary current distribution, the fitting of the first points yields a high Tafel slope for the cell operation performance. In spite of being a limited model for the cell performance, this is one of the least analytical and exact solved solutions obtained from mass balances in the course of the hydrogen electrooxidation and oxygen electroreduction. We consider that this situation would probably put some more knowledge in the understanding of the PEMFC functional description.

Mesoporous alumina which contains only Lewis acidity was synthesized by sol-gel method and was then impregnated with sulfuric acid to generate Brönsted acidity. The catalyst was used in Friedel-Crafts alkylation of resorcinol with methyl tert-butyl ether to produce 4-tert-butylresorcinol and 4,6-di-tert-butylresor- cinol as the major and minor products respectively. It was demonstrated that Lewis and Brönsted acidities play a synergetic role in this reaction.

Carbonmonoxide oxidation mechanism was studied over the 50/50 Ag-Co and 50/50 Co-Ce mixed oxide catalysts. The temperature programmed methods (TPR-H2 and TPD-CO) were used to characterize the catalysts. FTIR spectrums were collected under different feed conditions in order to determine the reaction mechanism. The carbonates adsorption bands and gas phase CO2 bands were obtained for both of the catalysts. CO linearly bounded to Ag+ sites at 2164 cm-1 and to Co3+ sites at 2105 cm-1 for 50/50 Ag-Co mixed oxide catalyst. CO linearly bounded to Co3+ sites at 2173 cm-1 and 2108 cm-1 for 50/50 Co-Ce mixed oxide catalyst. The CO adsorption studies showed that the CO reacted with surface oxygen species. The CO2 adsorbed on the catalyst surface as surface carbonate species. The oxidation of CO with surface oxygen species is probably via a non-competitive Langmuir-Hinshelwood mechanism on the catalysts.

Three-dimensional, transient turbulent particulate flow in an FCC riser is modeled using an Eulerian/Granular approach. The turbulence in the gas phase is described by a modified realizable (kg-?g) closure model and the kinetic theory of granular flow (KTGF) is employed for the particulate phase. Separate simulations are conducted for a rectangular and a cylindrical riser with similar dimensions. The model predictions are validated against experimental data of Sommerfeld et al (2002) and also compared with the previously reported LES-KTGF simulations of Hansen et al (2003) for the rectangular riser. The (kg-?g)-KTGF model does not perform as well as the LES-KTGF model for the riser with a rectangular cross section. This is because, unlike the more elaborate LES-KTGF model, the simpler (kg-?g)-KTGF model cannot capture the large scale secondary circulations induced by anisotropic turbulence at the corners of the rectangular riser. In the cylindrical geometry, however, the (kg-?g)-KTGF model gives good prediction of the data and is a viable alternative to the more complex LES-KTGF model. This is not surprising as the circulations in the riser with a circular cross section are due to the curvature of the walls and not due to the presence of sharp corners.

Evaporative liquid feeds are often introduced into gas-solid systems through horizontal nozzles in many industry applications. The interactions of gas, particles and evaporative spray play key roles in affecting process efficiency and product quality. Good understanding of the fundamental hydrodynamics of this phenomenon is essential to the design improvement and process optimization. In this work, an Eulerian multi-fluid model for evaporative spray in gas-solid flows is proposed and a three-dimensional numerical simulation of a gas-liquid nitrogen jet in a uniform gas-solid crossflow is performed. In this model, the droplet evaporation and interphase heat transfer are modeled with appropriate semi-empirical correlations. Detailed numerical results of the flow field are obtained and the predicted temperature distribution is compared with experimental measurements in the literature. The evaporative spray jet is investigated under different particles loadings and the effect of spray evaporation on the flow behavior is discussed. Finally, parametric studies are conducted to evaluate the effects of droplet size, jet velocity on the jet behavior.

Chemical-looping combustion (CLC) is a promising technology to capture carbon dioxide (CO2) inherently and conveniently without the additional apparatus. At present, for some metal oxide oxygen carriers, the high costs and the positive hazards to the environment inhibit the developing of CLC systems. The feasibility of using CaSO4 oxygen carrier in the CLC system is studied in this paper. Through the thermodynamic analysis, the carbon deposition and the sulfur evolution are studied in the reaction between CaSO4 and a typical syngas. In addition, providing that hydrogen (H2) is fed as the gaseous fuel in the CLC system, the kinetic analysis is investigated on the reduction of CaSO4 by H2 and the oxidation of calcium sulfide (CaS) by oxygen (O2) through the thermo-gravimetric apparatus (TGA). The kinetic models are built on the reduction and the oxidation of the oxygen carrier. The results calculated from the models agree well with the experimental data. Finally, the possible reaction mechanisms for the reduction and the oxidation are explored.

Numerical modeling of selective toluene disproportionation reaction over modified ZSM-5 zeolites to produce p-Xylene was developed and validated. The results of parametric analysis using the authenticated model provide an optimum guideline for the selection of appropriate operating conditions to achieve maximum toluene conversion and p-Xylene selectivity and yield. The predicted data indicate that increasing feed temperature from 450 to 600°C at constant (WHSV)-1 enhances the toluene conversion by 150%. Low weight hourly space velocities ((WHSV)-1=100 g.h/mol) and feed temperature (450°C) provides 99% p-Xylene selectivity. Moreover, at constant feed temperatures of 450, 500, 550 and 600°C, the maximum p-Xylene yield (? 0.087) occurs at 1300, 650, 330, and 175 g.h/mol, respectively, which clearly demonstrates that operation at higher feed temperature reduces the needed reactor residence time. Despite of imposed adiabatic condition, the model prediction demonstrates that an almost isothermal behavior prevails inside the reactor (2°C decrease in reactor temperature) due to the low heat of reaction (<1kJ/mol).

The separation of emulsified kerosene in water (concentration 250-750ppm) was investigated in a bubble column15.6 cm diameter and 120 cm height. The effective behaviors of bubble characteristics (bubble diameter, bubble rise velocity and air hold-up) on the removal efficiency were measured by electroresistivity probe. The effects of kerosene concentration, air flow rate,bubble diameter, liquid height, liquid viscosity, NaCl concentration, and alum on the removal rate were found. The experimental results showed that the removal efficiency increased with increasing air flow rate (1.09-2.6cm/s) and decreased with increasing CMC concentration. The results also showed that adding anionic surfactants (SLES and SDBS) leads to increase removal rate. The the flotation process was found to be first order kinetics. New correlations of air holdup and bubble diameter using dimensionless groups were derived.

Utilization of biomass gasification technology is not widely adopted due largely to tars contained in the product gas that pose serious problems, especially in engine use. In this paper, a laboratory scale plasma system for light tar cracking was developed. The system was based on non-equilibrium plasmas generated from two gliding arc plasma in series. Light tar components were represented by naphthalene in nitrogen flow, generated at constant rates between 130 – 690 mg/m3. Destruction efficiency and specific energy use were evaluated. It was found that destruction efficiency in the range of 70 – 95% could be achieved with a simple, single stage reactor. Plasma assisted tar decomposition was found to increase with applied electrical energy. Complete destruction (>99%) of light tars was obtained with the two-stage, gliding arc plasma system with applied electrical energy of about 1.8 – 2.9 kWh/m3.

In this study the mathematical modelling of a catalytic microstructured plate reactor for the production of hydrogen was performed in 2D and 3D geometry. The proposed reacting system uses the heat generated by an exothermic reaction (combustion) to sustain endothermic reforming reactions. Therefore, it pertains to those devices useful for producing the feed for fuel cell system for the remote generation of electrical power. However, because of the compactness of the reacting system it can also be considered in the context of apparatus aiming at process intensification. Within this frame the catalytic contribution of both exothermic and endothermic reactions was modelled considering the classic Langmuir-Hinshelwood surface kinetic theory. The advantage of using a real 3D geometry configuration consists in the possibility of considering the importance of the entering and boundary effects with particular attention to fluid stagnation and heat hot spots. The trade off of such a choice is certainly the huge increase of computing time and/or of the power of the computing facility. With respect to other works performed with similar reactor geometry and reacting systems this does not use simplifying assumptions such as catalyst layers modeled by one-dimensional approach, fully developed laminar flow or transverse heat and mass transfer taken into account through lumped heat and mass transfer coefficients. Results of simulations presented here concentrates on the comparisons between results of: countercurrent (CTC) and concurrent (CNC) flow patterns of the reactant streams; of simulations carried out with 2D and 3D models and of the influence of the thickness of the catalytic layers on the reactor performance. Simulations indicates that CNC flow pattern of reactants streams allows a better performance of the reactor since positive temperature differences between the catalyst layers and the gas in the channels maintain along the whole reactor and, consequently, there are not heat flux inversions, which occur under CTC flow pattern. Results also showed that as concerns an adiabatic reactor, whatever the operating conditions, 2D and 3D models yield substantially the same results. Finally, modelling demonstrated that for a realistic catalyst layer configuration thicknesses larger than 50 µm are useless for enhancing the reactor performance. The feasibility of the model proposed may show its potential in fast and easy implementation of several combustion and reforming fuels so to significantly enhance the performance prediction of real processes.

We investigate a model for the production of ethanol through continuous fermentation using Saccharomyces cerevisiae in a single reactor and cascades of up to five reactors. Using path-following methods we investigate how the ethanol productivity varies with the residence time in each reactor of the cascade. With a substrate feed concentration of 160 g/l we find the optimal productivity is 3.80 g/l/h, 5.08 g/l/h, and 5.18 g/l/h in a single reactor, a double reactor cascade and a triple reactor cascade respectively. For the case of a cascade containing reactors of equal size we investigate reactor configurations of up to five reactors and find that the maximum productivity is obtained in a cascade containing three reactors.

Three solids flow models for gas – flowing solids – fixed bed contactors are analyzed. They all presume axial dispersion in the dynamic, freely flowing zone, but they differ in the interpretation of the stagnant zone. The models have been examined and the model parameters have been optimized on the basis of two types of tracer experiments. One provides step response curves for flowing solids at the exit and the other presents the response curves of the static flowing solids holdup. The model which assumes axial dispersion and exchange between dynamic and two active static zones, most accurately describes the solids flow pattern. A simpler model which presumes exchange between dynamic and one static zone can be used if there is no need for a precise description of the behavior of stagnant particles. The most simple axial dispersion model is not realistic, as it does not explain stagnancy at all, which was experimentally observed for the gas – flowing solids – fixed bed contactors.

This work studies the effects of homogeneous chemical reaction and thermal radiation on coupled heat and mass transfer by free convection from a surface embedded in a fluid-saturated porous medium. Two different cases of thermal and solutal boundary conditions, namely the prescribed surface temperature and concentration (PSTC) case and the prescribed heat and mass fluxes (PHMF) case are considered. The governing boundary-layer equations are formulated and transformed into a set of non-similar equations. The resulting equations are solved numerically by an accurate and efficient implicit finite-difference method. The obtained results compared with previously published work and found to be in excellent agreement. A representative set of results is displayed graphically to illustrate the influence of the radiation parameter, chemical reaction parameter and the permeability of the porous medium on the velocity, temperature and concentration fields as well as the local skin-friction coefficient, local Nusselt number and the local Sherwood number.

The most common reaction system studied for the application of pervaporation (PV) is an esterification reaction between alcohol and acid in the presence of a catalyst. In present paper, performance of pervaporation reactor (PVR) for esterification of acetic acid with ethanol was studied. Model equations were developed for reaction and separation in PVR. Model results were validated with experimental results and excellent comparison was obtained. The effect of various parameters such as: reactant ratio, ratio of effective membrane area to volume of reacting mixture, catalyst concentration and flux on the performance of PVR were discussed. The optimum conditions were obtained as: membrane area to volume of reacting mixture = 2 m-1, reactant ratio = 1.5, catalyst concentration = 50 g/l for esterification of acetic acid with ethanol in PVR. The model presented can also be used for the other esterification reactions. The described model allows the evolution of the reaction time necessary to achieve a given conversion. The process parameters: temperature, catalyst concentration, initial molar ratio of acid to alcohol, the ratio of the effective membrane area to the volume of reacting mixture can be changed in order to attain the optimum operating conditions of the pervaporation-esterification coupling operating.

Supercritical Water Oxidation (SCWO) processes have been studied by numerous researchers. The effectiveness of this approach to treat a wide variety of wastes has been proved and the kinetics involved in some cases have been described. Phenol is commonly present in industrial wastewaters and it is extremely toxic. Hence, phenol is a model pollutant that has been the subject of numerous studies by SCWO on a laboratory scale. In this work, a pilot-scale SCWO system has been used to compare experimental and predicted conversions in the SCWO of phenol, using the reaction kinetic equations obtained at the laboratory scale. In this context, “PROSIM PLUS” software was employed to develop a simulator for the pilot plant facility, with the reaction kinetic parameters adjusted to represent the experimental data. In this study it was necessary to determine the thermal losses between the experimental reactor and its surroundings. These thermal losses were obtained from tests with pure water and oxidant streams in the absence of chemical reaction. An equation that predicted the effect of flow rate and temperature on the thermal losses was used. Experimental oxidation tests were conducted with initial temperature in the range 380 to 425 ºC, at 250 bar and phenol concentrations ranging from 1 to 12 g/l. Good agreement in the simulation was obtained by adjusting the kinetic parameters within their confidence range. This simulator was used to optimize the SCWO of phenol solutions in the pilot plant facility.

An indigenous novel strain of Ganoderma lucidum IBL-06 was investigated for the production of ligninolytic enzymes including lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase using different lignocellulosic substrates in still culture solid-state fermentation (SSF). The fermentation flasks were inoculated and incubated at 35°C for 14 days. Samples were harvested after every 48 h to study the profile of ligninolytic enzymes produced by the fungus on different substrates. Maximum enzyme activities were noted on 10th day of incubation on rice straw. Ganoderma lucidum IBL-06 produced highest activities of lignin peroxidase (LiP) among the lignolytic enzymes. By optimizing the SSF process, maximum activities of LiP (2185 IU/ml), MnP (1972 IU/ml) and laccase (338 IU/ml) were achieved after three days incubation of rice straw at pH 4.5; temperature, 35°C; moisture, 75% and inoculum size, 6 ml, using fructose as carbon source, urea as nitrogen source, Tween-80 as surfactant and veratryl alcohol as mediator.

Hydrocracking is an important upgrading process in the petroleum refinery, and it is generally used to process feedstocks ranging from vacuum gas oil (VGO) to vacuum residue. In this work, hydrocracking of VGO using a dual functional amorphous catalyst was carried out at a pilot scale unit under the following reaction conditions: liquid hourly space velocity (LHSV) from 1 to 1.5 hr-1 and reaction temperatures of 360-440°C at the constant pressure and hydrogen to oil, 156 bar and 1780 Nm3/m3, respectively. The effluent of the reactor was characterized to dry gas, naphtha, kerosene, diesel and unconverted VGO or residue. The pilot tests demonstrated that performing experiments beyond the temperature, recommended by catalyst vendor, lead the process to unstable hydrocracking. To describe the yield of hydrocracking products a five-lump discrete lumping approach with ten reactions was proposed. At first, the kinetic model contained twenty kinetic constants which were estimated by using the conventional objective function. The estimated parameters showed that the tendency of the catalyst to convert VGO to gas and naphtha was negligible whilst rate constants for hydrocracking of VGO to middle distillates were considerably high which was compatible with the nature of amorphous hydrocracking catalysts. After evaluating the magnitude of reaction rates and eliminating the ignorable constants, the network was reduced to six reactions in which only nine parameters were needed. The predictions indicated that the latter network could fit the yield of products more acceptable as if the average absolute deviation between experimental and calculated yields was descended from 16.25% to 12.6%. Then, to have a better prediction, a weighted objective function was used in which weight factors were calculated by a proposed weighted least square expression. The results confirmed that this approach could reduce average absolute deviation of model to 10.75%, and it created a fairly even distribution of deviation between hydrocracking products.

The main contribution of this work is to propose the use of a statistical procedure to generate simplified models from a detailed deterministic one for Real Time Optimization. Such models are also used as a tool to map the optimal and feasible region. These simplified models are useful in online optimization coupled to control implementations, since detailed rigorous models may demand time and high computational burden for their solution, which hampers the success of online purposes. In order to illustrate the application of the procedure, a three-phase catalytic reactor was considered. A dynamic heterogeneous mathematical model formulation of the o-cresol hydrogenation reaction was used to simulate the reactor steady-state response to different inlet conditions. The proposed statistical procedure (factorial design) generated simplified models for the reactor exit temperature and the reactant conversion, two useful pieces of process information. The use of these models in an optimization problem is then presented as an illustration of their application in an online real time optimization in a two-layer fashion. The simplified models turn possible the identification of the range of optimal solutions as well as the mapping of the region of optimal solutions very quickly compared to the use of full models, allowing the system to be flexibly operated at high level of performance.

Enhancement of Brønsted acidity in silica-titania aerogel was achieved by loading both sulfate and vanadium onto the material. This phenomena could be due to formation of V(OSi)2OH-O-SO3- in the resulted sample. In contrast, no noticeable Brønsted acidity was detected in vanadium loaded silica-titania aerogel (V/ST). UV-vis DR analysis results showed that the amount of hydrated tetrahedral titanium species, which acts as oxidative site, increased significantly upon sulfation and vanadium loading on the surface of the aerogel. However, presence of vanadium in the samples tended to transform framework tetrahedral titanium to extra framework octahedral titanium structure. The catalytic performance of the samples were evaluated in consecutive transformation of 1-octene to 1,2-octanediol through formation of 1,2-epoxyoctane using aqueous H2O2.

The determination of the optimal distribution of the catalytic activity profile, which maximizes the catalytic effectiveness and the selectivity, in created unsteady state conditions, is analyzed and treated numerically for the case of a consecutive-parallel reaction scheme. The optimal active element distribution is always a Dirac-? function, i.e., all the catalyst is deposited at a specific distance from the center of the catalytic pellet. The main result is that the location of this optimal position varies with time and that the modulation, of the temperature and the reactants concentrations of the external bulk fluid, leads to a considerable increase of the catalytic effectiveness. On the other hand the selectivity was found to be not affected by the modulation except for higher values of ?2 (?2>0.3).

The esterification kinetics of methacrylic acid with methanol in the presence of H3PW12O40 or H3MoW12O40 as a catalyst was studied with isothermal batch experimental. The catalyst concentration was varied between 14.4 and 57.7 mol/m3. The experiences were carried out at temperatures from 316 to 333 K and initial molar ratios of the reactants from 3 to 10. The non-ideality of the liquid phase was accounted for by using activities instead of molar. The activity coefficients were determined using the UNIFAC method. The kinetic equations developed had a non-elementary form, and the order of the reaction was a fraction.

In this research, we have demonstrated the feasibility of fabrication of a novel metal membrane by wire arc spraying. The feedstock wires were made of carbon steel (1.1% C, 1.9% Mn, and 1.8% Cr). The effects of stand-off distance between the gun and the substrate and the pressure of atomizing gas on the oxides, the porosity and mean pore size of the prepared membranes were studied. The SEM micrograph showed that the prepared membranes are asymmetrically porous. They were not uniform. The performance of prepared membranes was elucidated using gas stream containing hydrogen sulfide. The membranes with higher porosity exhibited gas permeability. Hydrogen sulfide reacts with the available iron in the membrane and produces iron sulfide and hydrogen. Hydrogen sulfide was considerably removed from the gas stream. The EDX test on the reacted membrane indicated that FeS covered the active surface of the metal membrane.

The cycloaddition reaction between isoamylene and ?-methylstyrene yields indane compounds 1,1,2,3,3,-pentamethylindane and 3-ethyl-1,1,3-trimethylindane, which are intermediate cyclic products used in the synthesis of musk fragrances. This exothermic reaction is conventionally carried out industrially in large semi-batch reactors, which have high heat and mass transfer resistances, are difficult to optimize, and scale-up. Aqueous sulfuric acid is conventionally used as the catalyst for the cycloaddition reaction, but solid catalysts offer many advantages over the corrosive aqueous sulfuric acid catalyst including the elimination of expensive separation and purification steps, and the need to use corrosion resistant materials of construction. A microreactor, which has enhanced heat and mass transfer characteristics, high surface to volume ratio, and improved fluid mixing, was used for the reaction using an acidic solid catalyst, Filtrol-24. A parametric study to obtain the dependence of product yield, reactant conversion and space-time yield on process variables such as catalyst particle size, residence time, velocity, temperature, pressure and the molar ratio of the reactants in the feed, was conducted. Through this study the optimum reaction conditions were obtained. The cycloaddition reaction was also performed in the semi-batch reactor using Filtrol-24 catalyst in order to compare its performance to that of the microreactor. Higher product yields were obtained in the microreactor compared to the semi-batch reactor, and the space-time yield in the microreactor was 4.8 times larger than that obtained in the semi-batch reactor at optimum reaction conditions in both reactors.

A new integrated photoreactor was assembled using a newly designed source, emitting both microwave power and UV radiation inside the reacting medium. The method is highly flexible and cheap, eliminating the need for the multimode and monomode microwave applicators, which are currently used for the excitation of a microwave electrodeless lamp. The characteristics of the source and the results from the decolorization of Acid Orange AO7 in an aqueous solution with hydrogen peroxide are presented. The decolorization process was carried out in batch condition and as continuous treatment and the effective reaction constant of the processes are reported. The experiments show that the photoreactor could be suitable for industrial application.

For characterization or optimization process, a computer prediction model is in demand. This paper describes an approach for modeling a delayed coking process using generalized regression neural network (GRNN) and a double-chain based DNA genetic algorithm (dc-DNAGA). In GRNN, the smoothing parameters have significant effect on the performance of the network. This paper presents an improved GA, dc-DNAGA, to optimize the smoothing parameters in GRNN. The dc-DNAGA is inspired by the biological DNA, where the smoothing parameters are coded in the double-chain chromosomes and modified genetic operators are employed to improve the global search ability of GA. To test the performance of the constructed model, it is used to predict the output of the test data which is not included in the training data. Compared with other reported methods, eight cross validation results show the advantage of the proposed technique that it predicts the new data more accurately.

Cobalt oxide was synthesized by mechano-chemical process in solid phase and was characterized by particle size analysis, nitrogen adsorption, XRD and DRIFT. A study was performed to evaluate the catalytic activities of cobalt oxide for oxidation of benzyl alcohol in liquid phase, using toluene as solvent. Benzaldehyde and benzoic acid were identified as the reaction products. Effects of various parameters like reaction time, temperature, catalyst loading and partial pressure of oxygen on reaction performance were studied. Activation energy was found as 46.14 kJ/mol. Langmuir-Hinshelwood type of mechanism was found to be applicable to experimental data. The catalyst was found to be heterogeneous in nature, which can be easily separated from the reaction mixture by filtration.

Dimethyl ether (DME) is a green fuel that commercially produced in an adiabatic fixed bed reactor by methanol dehydration. In the present work, a shell and tube fixed bed reactor is modeled and optimized for DME production. The reactor is modeled based on mass and energy conservation equations as well as auxiliary equations. In order to estimate the DME production and temperature profile along the reactor, a one dimensional heterogeneous model consist of a set of nonlinear differential and algebraic equations has been solved numerically. Also, The DME production in the isothermal reactor is maximized by adjusting the optimal temperature distribution along the reactor using genetic algorithm. Then, the performance of the proposed isothermal reactor is compared with industrial adiabatic fixed bed reactor. Results showed the higher DME production rate and methanol conversion in the optimized reactor.

Methane decomposition in the presence of NiO-CuO/SiO2 catalyst into COx-free hydrogen and filamentous carbons was investigated. The reaction was performed in a vertical fixed-bed reactor at 700°C. The catalyst was prepared via conventional impregnation method. The amounts of NiO-CuO loaded on SiO2 were varied from 10 to 90 wt%. Examination of the effect of NiO-CuO loading disclosed that 80 wt% loading gave the highest yields of hydrogen and carbon, being 2344 mol H2/mol NiO+CuO and 18600% respectively. Transmission electron microscopy and scanning electron microscopy were used to study the texture of the spent catalyst. It was demonstrated that the carbonaceous deposits on the catalyst were made up of filamentous carbons. Depending on the loading amount, the structural properties of the filamentous carbons changed.

Two types of kinetic modeling, continuous and discrete lump model were studied and compared in this research in order to model the industrial scale VGO hydrocracking process. The experimental data obtained from a pilot-scale fixed bed reactor over Ni-Mo/Silica-Alumina catalyst in a wide range of operating conditions was used for prediction and tuning the kinetic parameters using Genetic algorithm. In this study, the discrete lump model with four parallel reactions to four lumped products showed more convergence to the experimental data than the continuous lump model. Afterward, the discrete kinetic model was used to simulate the vacuum gas oil (VGO) industrial hydrocracking reaction accompanied by catalyst deactivation. The activity of the catalyst was taken as a time dependent variable and the first year of operational data were used to derive the deactivation parameter. The refinery test runs spanning over the last two and half years of operation were used to validate the model and interpret the simulation results. A comparison between the industrial and the predicted data showed that there is a good agreement between them and the presented model provides a reasonable fit to estimate the product yields of LPG, naphtha, kerosene, diesel.

Gasification of black liquor is an alternative recovery technology. Pulp and paper industries are turning their attention to black liquor gasification as a replacement for recovery boilers. Gasification-combined cycle exergoeconomic analyses have been used to study the economical and exergetical performance of black liquor. Both conventional iterative exergoeconomic optimization and multi objective evolutionary optimization have been applied. The iterative optimization results have been compared with evolutionary programming results in order to evaluate the accuracy. The strength of proposed optimization methods are elucidated in a case study applied to Mazandaran Wood and Paper Industries Co. Exergetic efficiency of total system can reach up to 58.3% while it is restricted to 57.0% when using the evolutionary optimization. However, the product cost achieved by evolutionary optimization is about 1.0% less than that of iterative optimizations.

The use of the Fenton's process for the depuration of a post-biological treated milk whey wastewater was studied, aiming to achieve adequate operational conditions for a cost effective treatment to generate a suitable effluent to be directly discharged into the natural water courses. A design of experiments was implemented in order to understand the role of the independent parameters and their combinations over the treatment process. From our results the hydrogen peroxide concentration and the ratio between [H2O2]:[Fe2+] as well as their interaction were statistically important concerning both TOC and COD removal. The experiments performed at the highest value of [H2O2] and at the lowest level of [H2O2]:[Fe2+] lead to effluents accomplishing the environmental legislation. Moreover, toxicological tests revealed that the treated effluent was harmless to the ecosystems. A cost estimation analysis was performed and the catalytic activity of the remaining sludge from the homogeneous process was checked. This activity decreases with the number of reuses which reduces the possibility of the direct utilization of the sludge.

This article describes the energy and exergy analysis of the reduction zone in a downdraft biomass gasifier. A simplistic formulation for describing the pyrolysis and oxidation of these products has been presented for initialization. Equilibrium and kinetic models are used to predict the reduction products leaving the reduction zone and thus the 1st law efficiency. In the reduction zone, exergy destruction due to chemical, physical, compositional, internal heat transfer and heat loss to the surrounding has been quantified to describe 2nd law efficiency. The comparison of equilibrium and kinetic models is carried out with experimental data for general validity. Parametric analysis of char bed length and inflow temperature on gas composition, un-converted char, exergy destruction, 1st law and the 2nd law efficiency has also been carried out. Simulation results identified a critical char bed length (where all char gets consumed) for a given feedstock, which depends on residence time and reaction temperature in the reduction zone. Near critical char bed length, predictions show high calorific value of gas with relatively less exergy destruction and thus optimum reactor performance. The accuracy of the prediction depends on the validity of initial input conditions.

This study identified the effect and importance of the start-up period on methane production. Methane production was studied during the start-up period of semi-continuous stirred tank reactor (SCSTR) of anaerobic suspended growth under mesophilic conditions (37±3°C) with semi-continuous feeding. Two reactors were seeded with an inoculum of rumen fluid (5% and 10%) and mixed with anaerobic granular sludge (95% and 90%) as a substrate, respectively. The anaerobic digesters were filled up with 800 ml of these seeds during feeding phase. A supernatant of raw Palm oil mill effluent (POME) was fed in semi-continuous mode during the stabilization phase. The pH of the digesters was kept within the range of 7.2 -7.5 without any adjustment during this period. The effects of different concentration of seeding, MLVSS and COD (mg/L) on the quantity of produced methane during the start–up period were studied. The results showed that during the feeding phase methane content was 82.10% and 81.34% for both mixtures. But at the end of start-up period both reactors have the same percentage which is around 55%. Higher methane production occurred during the feeding phase for the second mixture. MLVSS and COD concentrations have a direct relationship with the methane obtained.

The present experimental data on minimum fluidization velocity for two-phase and three-phase fluidized beds, involving 459 measurements were used for the analysis. Apart from this, 70 literature data points from different published sources, using 11 different liquids and 11 different particles have been used for the development of minimum fluidization velocity correlation. The developed correlation for the prediction of the minimum fluidization velocity for two-phase and three-phase fluidized beds was found to be satisfactory for the Newtonian and non-Newtonian systems with a wide range of variables covered in the present investigation.

Marine Bacillus circulans used in this study produced 2.58 g L-1 of biosurfactant when grown in unoptimized modified marine medium (MMM). The biosurfactant production was enhanced by optimizing the critical components of the MMM using statistical modeling based response surface methodology (RSM). From the results of single-factor-at-a-time optimization experiments; glucose, urea, SrCl2 and MgSO4 were identified as critical components that affected biosurfactant production significantly. In RSM optimization, experiments were done based on the 24 full factorial central composite design to generate responses, which were used to fit the quadratic polynomial model. Statistical analyses of the data of model fitting were done by using Design Expert version 7.0. The optimum values obtained for the test components for the maximum predicted biosurfactant concentration of 3.04 g L-1 were found to be (in g L-1): glucose = 35.5, urea = 1.23, SrCl2 = 0.11 and MgSO4=0.53. Validation experiments using the optimum values of the critical media components showed that the biosurfactant yield was enhanced to 3.01 g L-1, which was in close agreement with the model prediction. Thus, the biosurfactant production was increased by 17% in the optimized MMM, when compared to that in unoptimized medium.

Biomass Refinery is a sequential of eleven thermochemical processes and one biological process with two initial basic treatments: prehydrolysis for lignocellulosics and low temperature conversion for biomass with medium-to-high content of lipids and proteins. The other ten processes are: effluent treatment plant, furfural plant, biodiesel plant, cellulignin dryer, calcination, fluidized bed boiler, authotermal reforming of cellulignin for syngas production, combined cycle of two-stroke low-speed engine or syngas turbine with fluidized bed boiler heat recovery, GTL technologies and ethanol from cellulose, prehydrolysate and syngas. Any kind of biomass such as wood, agricultural residues, municipal solid waste, seeds, cakes, sludges, excrements and used tires can be processed at the Biomass Refinery. Twelve basic products are generated such as cellulignin, animal feed, electric energy, fuels (ethanol, crude oil, biodiesel, char), petrochemical substitutes, some materials (ash, gypsum, fertilizers, silica, carbon black) and hydrogen. The technology is clean with recovery of energy and reuse of water, acid and effluents. Based on a holistic integration of various disciplines Biomass Refinery maximizes the simultaneous production of food, electric energy, liquid fuels and chemical products and some materials, achieving a competitive position with conventional and fossil fuel technologies, as well as payment capacity for biomass production. Biomass Refinery has a technical economical capability to complement the depletion of the conventional petroleum sources and to capture its GHGs resulting a biomass + petroleum “green” combination.

Electrochemical cells with a rotating disc electrode are the preferred devices to characterize electrochemical reactions because simple analytical expressions can be used to interpret the information obtained from physical experiments. These equations assume that the velocity field in the vicinity of the electrode active face is in accordance with the ideal behavior described by von Kármán. Experimental liquid velocity measurements inside the cell reported in recent works suggest that the actual liquid flow pattern is not fully in accordance with the assumed ideal behavior. In this work, the Computational Fluid Dynamics technique was employed to characterize numerically the flow pattern inside the electrochemical cell. By using a three-dimensional model, symmetric conditions were not imposed. A biphasic system was employed to evaluate the influence of liquid free surface over the flow pattern. Unsteady state numerical simulations were performed using the commercial software Fluent. Multiple electrode rotation speeds and several cell sizes were employed. Contrary to the assumed behavior, it was obtained that the flow pattern inside the electrochemical cell is not symmetric due to the synergetic effect of the cell walls, the submerged electrode side wall and the liquid free surface. This work states that the differences between actual and the ideal flow patterns can be minimized with plain electrode and cell geometrical modifications.

A vertical spray pyrolysis reactor was designed to produce separated/softly agglomerated oxide nanoparticles by dissolving a large amount of high molecular weight polymer into solutions of nitrous or acetic metals. The polymer played a role as a matrix that prevented the tendency of as-grown nuclei to make contacts inside the “polymer ball.” Decomposition of the “polymer ball” at the end stage of the reactor released separated nanoparticles. On the first attempt, we produced particles of zinc oxide and compound oxide of CuO/ZnO/Al2O3 at different parameters of synthesis. We found that the size of the particles decreased, as a fraction of the polymer, as the mass increased. We used a percolation theory to explain the particle separation mechanism inside the “polymer ball.” Separated nanoparticles were obtained if the volume fraction of the particles was far below the percolation threshold.

The removal of phenol derivatives from waste waters is of great concern because of the extreme toxicity and persistency. The present study deals with the adsorption of p-nitrophenol from aqueous solution onto jute stick char. Jute stick is a solid waste obtained from the agricultural firms and jute industry. Batch studies were carried out with synthetic wastewater having p-nitrophenol concentration of 1000 ppm using jute stick char as a low cost adsorbent. The operating variables studied are adsorbent dose, pH, contact time, effect of salt addition, and initial p-nitrophenol concentration etc. The adsorption data was analyzed using Freundlich and Langmuir models. The experimental results showed that Freundlich model appear to fit the isotherm data better than the Langmuir model. Optimum conditions for p-nitrophenol were found to be at pH= 7.6 and equilibrium time 5 h. The pseudo-second order kinetic model provides the best correlation of the experimental data compared to the pseudo-first-order kinetic model.

Bioreactor control is an important area of research concerning continuous microorganism cultivation. The possible occurrence of the substrate inhibition phenomenon or substrate deficiency engenders the necessity to the control the substrate concentration. Moreover in order to maintain the dissolved oxygen content in an appropriate range, the biomass concentration should not exceed the set out level. To maintain the substrate and biomass concentration in certain desired ranges, a proposal of a new chemostat with pulse state feedback control is presented in the work. Then, a universal mathematical model of the chemostat is formulated, and the dynamic properties of the model including the existence and stability of the periodic solution are discussed. After this, in order to optimize the biomass production, two objective functions are introduced and the optimization is performed. The work shows that the proposed chemostat extends functionality of a chemostat providing in easy way the control of biomass and substrate concentration. The analytical results presented in the work are validated by numerical simulations.

In this work, the capability of genetic algorithms (GAs) to optimise an alternative fermentation process for the production of biobutanol was assessed. The process consists of three interconnected units, as follows: fermentor, cell retention system (tangential microfiltration) and vacuum flash vessel (responsible for the continuous recovery of butanol from the broth). The dynamic behaviour of the process is described by a non-linear mathematical model with kinetic parameters determined experimentally, whose non-linearity makes the solution of the optimisation problem difficult through conventional algorithms, thus justifying the use of an evolutionary method based on the GAs. The objective of the optimisation was the search of the process inputs that maximises the productivity of butanol for a desired substrate conversion. The potential of binary and real coded genetic algorithms to solve the optimisation problem was assessed. The GA parameters were evaluated making use of the statistical technique of the factorial design in order to identify the most significant ones to the GAs response and to determine the values of the parameters that improve the GAs performance. With both GA codes similar solutions to the optimisation problem were obtained. However, in relation to computational time, the binary code outperformed the real code. The optimised process ran on concentrated sugar solution (140.7 g/l), reaching a high final butanol concentration (27.1 g/l) and high butanol productivity (9.0 g/l.h). The use of mathematical optimisers in the butanol fermentation is a novel approach and sums up the efforts of recent researches in turning the biobutanol industry commercially viable.

Pyrolysis was performed on wheat grains untreated or impregnated with nickel nitrate solutions, into a fixed bed column, in the presence of a carbon dioxide stream. This produced a char with or without nickel, pyrolytic oil and a gaseous fraction. The distribution of these fractions was dependent on variations in heat flux, carbon dioxide superficial velocity and nickel nitrate solution concentration. The paper focused on establishing the qualitative and quantitative influence of these experimental variables on pyrolysis dynamics. In order to obtain a process characterization, a factorial experiment was used, wherein the pyrolysed material mass, collected oil mass, operating time, material bed temperature, volatiles temperature and column wall temperature were the evaluated process responses. A model reproducing pyrolysis curves was proposed considering the process dynamics as a result of competition between the appearance and extension of local pyrolysis points.

The present work aims to study the fluidization and heat transfer characteristics around a single horizontal heated tube, in-line tubes arrangement and staggered tubes arrangement immersed in a gas fluidized bed. The experiments were carried out on a square test section column (16 cm x 16 cm x 95 cm) from a steel sheet of 3 mm thickness. Each arrangement of the tubes is installed in a separate test section. The plane tube bank for both in-line and staggered tubes arrangement consists of 5 rows and four tubes per row in equal vertical and horizontal pitch arrangement. The experimental setup has a transition channel with the same square section and 30 cm height. The other side of the transition channel has one hole of 5 mm inside diameter and 30 mm long to measure the pressure before the distributor plate. The bed material used is sand particles of different sizes (1400 µm, 1600 µm, and 1850 µm). For the tested arrangements, the results show that the average heat transfer coefficient increases with the increase of the fluidizing velocity and with the decrease in particle diameter. Also, the comparison between the in-line and staggered tube arrangement showed that, the average heat transfer coefficient in case of staggered is higher than that of the in-line tube arrangement. Moreover, empirical correlations for the average Nusselt number of the tested arrangements using the experimental data are presented.

The reactions of amino acids under subcritical water conditions were investigated. All reactions were carried out under a pressure value corresponds to the saturated vapor pressure of water at the employed reaction temperature (hereafter called the saturated subcritical water condition). The reaction temperatures were in the range of 503-563 K. As reactants, seventeen different amino acids were investigated including, glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, tyrosine, serine, threonine, cysteine, proline, lysine, histidine, arginine, aspartic, and glutamic. The obtained data revealed that the major decomposition pathway were the deamination and decarboxylation. It was found that glycine, alanine, valine, and proline were synthesized as intermediate decomposition products of other amino acids. Glutamic acid is the only amino acid that decomposed through lactamization process to pyroglutamic acid. Based on the experimental data a general decomposition pathway of all tested amino acids was developed by considering that the decomposition reactions extended to produce final decomposition products, carbon monoxide, water, and ammonia.

Oil palm leaf powders (OPLP), an agricultural waste material, were used as new non-conventional and low-cost adsorbents for the removal of copper (II) ions from aqueous solution. Batch studies were performed to evaluate and optimize the effects of various parameters such as contact time, pH of the solution, initial metal ion concentrations and adsorbent dosage. Langmuir, Freundlich and Temkin isotherms were used to analyze the equilibrium data at different temperatures. The experimental data fit well with the Langmuir adsorption isotherm, indicating thereby the mono layer adsorption of the copper (II) ions. The monolayer sorption capacity of OPLP for copper (II) ions was found to be 11.22 mg/g at 30 °C. The thermodynamic parameters like standard free energy, standard enthalpy, and standard entropy changes for the adsorption of copper (II) ions have also been computed and discussed. The heat of adsorption [?H° = -39.84 kJ/mol] implied that the adsorption was exothermic in nature.

Dimethyl ether (DME) is an innovative clean fuel that can be used in various ways in many different sectors including household, transportation, power generation, etc. In order to use DME as a fuel, it must be produced in a highly efficient manner. As part of fundamental research, a new efficient catalyst and slurry phase process for DME synthesis were developed. After testing was carried out at a pilot plant (5 tons/day), the demonstration plant (100 tons/day) project was implemented from 2002 to 2006. The conversion of DME in the slurry phase reactor is dominated by W/F (W: Charged catalyst weight, F: Gas flow rate in the reactor), regardless of reactor scale (1 kg/day – 100 tons/day). The gas hold up was measured by increasing the velocity of the gas up to 40 cm/s. Within this range, gas hold up increased smoothly without any sudden change of fluid phenomena or any negative effect on the chemical reaction. There is no clear dependence of the gas hold up on the reactor diameter. The mixing diffusion coefficient in the slurry phase and the heat transfer coefficient from slurry to heat exchanger tubes were determined. Based on these data, a process simulator has been developed that predicts that commercial scale production of 3,000 tons/day can be realized by a single reactor 7m in diameter and 50m high.

In this study, we present the homotopy perturbation method (HPM) for finding the analytical solution of linear and non-linear space-time fractional reaction-diffusion equations (STFRDE) on a finite domain. These equations are obtained from standard reaction-diffusion equations by replacing a second-order space deri-vative by a fractional derivative of order and a first-order time derivative by a fractional derivative of order. Some examples are given. Numerical results show that the homotopy perturbation method is easy to implement and accurate when applied to linear and non-linear space-time fractional reaction-diffusion equations.

The operational range for a gas-liquid-solid fluidized bed aerobic biofilm reactor with a low-density biomass support is limited: on one side, by a minimum fluidization gas velocity ugf; on the other side, by a critical gas velocity ugcr. In this study, the values of ugf and ugcr were determined for a reactor in which polypropylene particles of density 910 kg/m3 were fluidised downwards by an upward cocurrent flow of gas and liquid. The treatment of industrial wastewaters was also investigated to determine the optimal air velocities ugm for comparison with the ugf and ugcr.The values of ugf and ugcr were in the range 1.58 x 10-3 - 14.27 x 10-3 and 5.37 x 10-3 - 58.59 x 10-3 m/s, respectively. Hence, the values of ugcr were approximately 4 times larger than the corresponding ugf. The values of ugm were 0.021, 0.025 and 0.036 m/s for the initial values of chemical oxygen demand 26,790; 33,210 and 41,640 mg/l, respectively. Thus, the values of ugm were approximately 3.5 times larger than the corresponding ugf. On the other hand, the values of ugm were about 65% of the corresponding ugcr.The application of low-density particles in a reactor allowed the control of a biomass loading in the apparatus. After change in (Vb/VR) at a set ug, the steady-state mass grown on particles was achieved after approximately 4 days of operation. With change in ug at a set (Vb/VR), the new steady-state biomass loading occurred after the culturing for about 2 days and the loading was constant over the entire period of experimentation for this ug.

This work extends the development of backmixing-diffusion model by further removal of some assumptions from the previous works. The model covers for steady and unsteady state conditions in continuous countercurrent extraction and will be available for simulation purpose for reversing continuous countercurrent extractor (RCCE) in a more realistic ways, especially in beverage juice production. Solution of the modeling was carried out by numerical method, namely, an implicit finite difference. For the unsteady state condition, the Crank-Nicholson method was selected for calculation due to its stability; for the steady state one, the selected numerical method was center-difference formula with second order of magnitude of error, cooperated with Richardson’s extrapolation. Matrix inversions were done by Gauss Jordan method. Considerable verification was made by assuring the accuracy and stability of numerical method for both steady and unsteady state conditions in a practical range. It was found that the solution obtained from the developed model with aforementioned numerical method compared well with the well-established analytical solution whenever they are available. Generally, the numerical solutions gave high accuracy for the steady state condition, while still being acceptable for practical purpose.

In this work, a backmixing-diffusion model was developed for continuous countercurrent extraction process. Various parameters/factors influenced the extraction were investigated for juice extraction. Important parameters/factors studied were solid to liquid ratio, solid retention time, extraction temperature, external resistance to mass transfer, size and shape of solid materials and degree of backmixing for solid and liquid phase. For juice extraction from pineapple, apple and pear, it was found that the backmixing-diffusion concept can be used through the whole range of operation time. The model could predict the concentration profile well for both unsteady state period and steady state one. The simulation was successful for juice extraction process.

A model for a flow-by porous electrode electrochemical reactor operating under galvanostatic conditions has been used to study the removal of two different metal ions. The effect of the applied electrical current was investigated and the concentration, current and electrode potential distributions were calculated. Applied electrical current was used instead of a constant potential as a boundary condition.For a low applied electrical current (-3.5 Am-2), conversions of 54 and 5% were obtained for the first and second component, respectively, with a calculated cathode potential drop of (94 mV); a relatively homogeneous current distribution was observed, with a consequently efficient use of the porous cathode volume. For higher values (-10 Am-2), the first component was almost completely removed, whereas only 70% of the second compound was deposited and a larger cathode potential drop was estimated (477 mV). Moreover, a less homogeneous current distribution was obtained and the electrode volume was not used as efficiently as in the case of a lower applied current. These results have important implications in the ultimate reactor design and its analysis and evaluation, since uneven deposits would eventually provoke localized deposit buildup and flow channeling as well as poor reactor performance. Good agreement was observed between experimental and theoretical results published by other authors and the model presented here.

Several dynamic and steady-state methods have been proposed in the literature for measuring the mass transfer coefficient in gas-liquid stirred vessels. Analysis has also been developed about the fundamentals of the most interesting techniques. Similarly, the flow behaviour of the gas and the liquid phases has been modelled in various ways—the different models often resulting in different coefficient estimates. Cross checking of a number of techniques and of various models has already been performed for a number of cases. However, not all the implications are clear and have been retained, especially for high-aspect-ratio equipment stirred with multiple impellers.In this paper, the main problems in KLa characterisation are analysed: the most promising techniques and flow models are reviewed critically and several combinations of experimental methods and models have been tested with the purpose of providing information regarding their choice. Vessels stirred with sets of multiple impellers of different types as well as coalescing and non-coalescing gas-liquid systems have been considered. Recommendations about the use of some of the mentioned tools are also given in relation to the final use of the coefficient.

This investigation reports the experimental and theoretical results carried out to evaluate the volumetric mass transfer coefficient (kLa) in a novel hybrid rotating and reciprocating perforated plate bubble column. Countercurrent condition is performed. kLa is studied by the absorption of oxygen from air into deoxygenated water at room temperature (27 ± 1°C). Effects of agitation level, superficial gas velocity, superficial liquid velocity and plate spacing on kLa were analyzed and found to be significant. With an increase in agitation level at a constant superficial gas and liquid velocities, the breakage process of gas bubbles starts to be more pronounced and intensive oxygen mass transfer occurs. Hence, kLa increases sharply. kLa increases with an increase in superficial gas velocity, due to higher gas holdup and the enhanced breakup of bubbles. Similarly, kLa increases with an increase in superficial liquid velocity and the effect is found to be significant. When plate spacing is decreased (by increasing the number of plates), it is observed that the kLa increases at higher superficial gas velocity and agitation level. Correlation is developed for the determination of kLa and found to concur with experimental results. This correlation can be used for the determination of kLa for this hybrid column with 95% accuracy within the range of variables investigated in this present study.

Studies on two-phase gas-liquid co-current flow with non-Newtonian liquid system has attracted the attention of researchers over the years due to its wide-spread applications and importance in various different processes in chemical and biochemical industries, such as the process of two-phase in oil and gas wells, transportation systems of crude and refined products, and food processing in biochemical engineering and bio-reactors. This article examines the sole objective of experimental studies on gas holdup in Newtonian and non-Newtonian liquid slug flow within a range of gas and liquid flowrate of 0.5×10-4 to 1.92×10-4 m3/s and 1.6×10-4 to 6.7×10-4 m3/s, respectively. The present data was analyzed with different models. To predict gas holdup, correlations have been developed for individual system with Newtonian and non-Newtonian liquid. A general correlation was also developed to predict the gas holdup combing both the Newtonian and non-Newtonian liquid systems. The study of the gas holdup characteristics in gas-Newtonian and non-Newtonian liquid systems may give insight into a further understanding and modeling of this slug flow characteristics in industrial applications.

This investigation reports the experimental and theoretical results carried out to evaluate the axial dispersion number for an air-water system in a novel hybrid rotating and reciprocating perforated plate bubble column for single phase and two phase flow conditions. Axial dispersion studies are carried out using stimulus response technique. Sodium hydroxide solution is used as the tracer. Effects of superficial liquid velocity, agitation level and superficial gas velocity on axial dispersion number were analyzed and found to be significant. For the single phase (water) flow condition, it is found that the main variables affecting the axial dispersion number are the agitation level and superficial liquid velocity. When compared to the agitation level, the effect of superficial liquid velocity on axial dispersion number is more predominant. The increase in superficial liquid velocity decreases the axial dispersion number. The same trend is shown by agitation level but the effect is less. The rotational movement of the perforated plates enhances the radial mixing in the section; hence, axial dispersion number is reduced. For the two phase flow condition, the increase in superficial liquid velocity decreases the axial dispersion number, as reported in the single phase flow condition. The increase in agitation level decreases the axial dispersion number, but this decreasing trend is non-linear. An increase in superficial gas velocity increases the axial dispersion number. Correlations have been developed for axial dispersion number for single phase and two phase flow conditions. The correlation values are found to concur with the experimental values.

The paper deals with the use of the stochastic approximation method for estimation parameters of the fluidization process and detecting a change of the process mode based on experimental photographs of local part. The fluidization process is treated as a process of diffusion type, described by the diffusive equation. Because the solid particles are essentially discrete ones and the moments of process observation are also discrete, the diffusive equation is treated in the difference form. The problem of modeling of the fluidized bed is reduced to the estimation of coefficients of difference equations system. The method of stochastic approximation is used for this estimation. The method allows identifying the regime of the fluidization process in its dynamics and estimating the parameters of the process. The approach and the estimating algorithm were verified using the especial experiments.

This paper reports the experimental investigation of local convective heat transfer enhancement, flow friction and thermal performance factor behaviors in the tube fitted with the short helical tapes (SHTs) acting as decaying swirl flow generators. The tapes with three different helical tape angles (? = 90°, 135° and 180°) and three different channel numbers (N = 2, 3 and 4 channels) were tested under the uniform wall heat flux condition. The performance of each tape is compared with the performance of the plain tube subject to the same pumping power. The experimental results show that the heat transfer rates and friction factors of the tube with SHTs are respectively in range of 1.15 to 1.9 and 1.49 to 2.31 times of those in the plain, corresponding to thermal performances between 0.98 and 1.46. The correlations for Nusselt number (Nu) as a function of Reynolds number (Re), Prandtl number (Pr), helical tape angle (?) and the number of channel (N) are also developed.

Optimal ecological performance of generalized irreversible chemical engine cycles with both linear and diffusive mass transfer laws are derived by taking an ecological optimization criterion as the objective, which consists of maximizing a function representing the best compromise between the power output and the entropy production rate of the chemical engines. In this paper, the relations between the ecological function, power output, entropy production rate and the efficiency of a chemical engine cycle with irreversibilities of mass transfer, mass leakage and internal dissipation, in which the mass transfer, are derived. This paper also derives the maximum ecological function and the corresponding power output, entropy production rate and efficiency, the maximum power output and the corresponding ecological function, entropy production rate and efficiency, and the maximum efficiency and the corresponding ecological function, power output and entropy production rate. The results can provide some theoretical guidelines for the design of practical chemical engines.

A simplified mathematical model is proposed to determine the agglomeration tendency of bitumen-coated coke particles in fluid cokers. The model calculates a theoretical critical velocity that depends on key parameters such as the particle size, bitumen viscosity, and bitumen thickness; it also accounts for the temperature- and reaction-dependent variations of the bitumen thickness and viscosity. A peak theoretical critical velocity at the intermediate reaction times for all coking temperatures is predicted. By comparing this peak critical velocity with the estimated inter-particle collision velocities within an industrial-scale reactor, the agglomeration tendency of coke particles is determined within fluid cokers. The results show that at low temperature regions (T=400 °C), there is no agglomeration tendency; however, at high coking temperatures (T=503 and 530 °C), substantial agglomeration tendency is expected. It is also found that the number of coke particles constituting an agglomerate could be as high as a few hundreds.

The effect of superficial gas and liquid velocities and properties of solids on the minimum fluidization velocity and riser liquid holdup of a three-phase external loop air lift fluidized bed reactor was characterized using Newtonian and non-Newtonian systems. Water, 65% and 85% of glycerol and n-Butanol were used as Newtonian liquids and different concentrations of carboxymethyl cellulose (i.e. 0.2%, 0.5% and 1% CMC) were used as non-Newtonian liquids. Spherical glass beads, bearl saddles and rasching rings of different sizes were used as solid phases. The phase flow rates and properties of solid particles had significant effects on the hydrodynamic characteristics of the external loop air lift fluidized bed reactor, such as minimum fluidization velocity and riser liquid holdup. Unified correlations have been developed to estimate the minimum fluidization velocity and riser liquid holdup as a function of superficial phase velocities, properties of solid particles and physical properties of both Newtonian and non-Newtonian liquid systems. The predicting ability of the correlations were tested with the experimental data and found to be a good fit with an absolute average relative deviation (AARD) of ± 6.5 % and ± 7.8 % for minimum fluidization velocity and riser liquid holdup, respectively.

The effect of free stream turbulence intensity on heat transfer and flow characteristics around four in-line elliptic cylinders in cross flow was experimentally and numerically investigated. The elliptic cylinders examined had an axis ratio (b/c) of (1:3) with a zero angle of attack (where the major axis is horizontal) and were heated under a constant heat flux condition. Three different sizes of free stream turbulence producing grids (screen) inserted at a distance of 300 mm the upstream test cylinders are used to study the effect of the free stream turbulence. The turbulence intensity levels of 5.6%, 8.3% and 10.5% are obtained from the grid sizes. The effects of cylinder spacing ratio (L/c) were examined within Reynolds number (based on free stream velocity and major axis length) ranging from 3640 to 66240. It was observed that the local and average Nusselt numbers of the tested elliptic cylinders increase with increasing the free stream turbulence intensity. The results showed that the maximum enhancement ratio for the average Nusselt number (for the tested cylinder with grid and for the single elliptic cylinder without grid) was found to be about 1.93 and was obtained for the second elliptic cylinder in four in-line cylinders at L/c=1.5, Re=6150 with free stream turbulence intensity of 10.5%. Also, the flow characteristics varied drastically with both the longitudinal spacing ratio and the inserted grid (screen). Moreover, an empirical correlation for the average Nusselt number of the second elliptic cylinder of the four in-line cylinders was obtained as function of Reynolds number and free stream turbulence intensity.

The present study presents systematic experimental data on the fluidization of zeolite particles in water-solid fluidized beds. Four particle size groups, 90-180 ?m, 180-250 ?m, 250-315 ?m and 315-500 ?m and 22 different volumetric flow rates were used, corresponding to Rep of 0.012 to 1.452. All particle sizes showed smooth flow rate vs expanded bed height curves. As is proven, the Ergun equation is useful for determining the minimum fluidization velocity for the large particle sizes by using a fixed sphericity value of 0.354. For the fluidized bed regime (us>umf), the Ergun equation fails to represent the data as it results in fluctuating particle sphericity values, while the Richardson–Zaki model seems to correlate the data for the large particle sizes only. A new correlation is presented, connecting bed voidage to Rep for all particle sizes with an average relative error of 2.38±2.49% and the range is 0.02-9%.

Volumetric oxygen mass transfer coefficient is a decisive parameter for the selection of any contactor as an aerobic bioreactor. A pulsed plate column with fixed bed of solids in interplate spaces is a recent innovation in the field of immobilized cell bioreactors. Volumetric oxygen mass transfer coefficients are determined in a three-phase pulsed plate column involving air and water phases and with a fixed bed of glass particles, which can serve as a surface for cell immobilization packed in the interplate spaces. The volumetric mass transfer coefficients obtained in this column range from 0.067 to 0.1495 s-1 in the range of air superficial velocities from 0.011 to 0.047m/s and vibrational velocities from 0.825 to 6cm/s. Volumetric oxygen mass transfer coefficient has increased with the increase in superficial air velocity and vibrational velocity. Empirical correlation relating kLa with these variables was developed. The volumetric oxygen mass transfer coefficient values in the three-phase pulsed plate column are found to be similar or higher than the literature reported values for conventional two-phase pulsed plate columns. The values of volumetric oxygen mass transfer coefficients in the three-phase pulsed plate column are of higher order of magnitude than the literature reported values of volumetric oxygen mass transfer coefficient for many other three-phase gas-liquid-solid reactors. The pulsed plate column with fixed bed of solids is proven to have all the potential to be used as an aerobic bioreactor with immobilized cells due to its better gas-liquid mass transfer characteristics.

Intermittent fed-batch culture with total cell retention was evaluated during Bacillus thuringiensis serovar. kurstaki fermentations aiming to enhance biomass and spore concentration yields while maintaining toxicity. This method is derived from the already reported intermittent fed-batch culture and utilized a tangential flow filtration system for cell retention. After 4 pulses, we obtained a biomass of 74.36 g·L-1 and this biomass displayed a half lethal concentration towards neonate Spodoptera frugiperda larvae of 40.53 ng·cm-2, and spore concentration of 4.6 x 1014 CFU mL-1. On the other hand, volumetric productivity was increased seven-fold compared to batch fermentation. Interestingly, we are not aware of higher spore concentrations reported to date for B. thuringiensis cultures.

Size distributions of TiO2 nanoparticles synthesized in a propane/air flame CVD process have been simulated by CFD code Fluent. The flame is simulated by EDM and standard k-? model with non-equilibrium wall functions in the wall region. SIMPLE method is selected for pressure-velocity coupling and the convection term is discretized with first-order upwind scheme. Radiant energy absorption and irradiant are incorporated in the enthalpy balance by P1 model. Particle growth and size distributions are simulated by the implementation of integral collision kernel in particle dynamics and the condition of particle volume conservation into CFD code Fluent. Comparisons on number frequency size distributions between measured and predicted have been made and the results showed that the integral collision kernel gave reasonable predictions on both size and size distributions.

Coke formation reduction during naphtha pyrolysis was investigated using dimethyl disulfide (DMDS) and carbon disulfide (CS2) as inhibitors with different feed stocks. Different industrial nickel alloy steels such as stainless steel 304 and 316 (SS304, SS316), HP-modified (HP-mod) and HP-micro (HP-mic) were used as coupons in a quartz cylindrical reactor for coke formation studies. Coke formation significantly reduced in the presence of the additives or using feeds with more sulfur compounds. It was revealed that HP-mic alloy has the least coke deposition rate between other alloys. Scanning electron microscope (SEM) and energy dispersive X-ray analyzer (EDAX) were used for morphological and elemental surface analyses, respectively. It was found that cokes formed in presence of sulfurous inhibitors are softer and have less metal concentrations.

A locally isolated fungus, Agaricus bitorqus A66, was used for the development of bioremediation process for synthetic solutions of direct dyes. In the initial screening study, the decolorization of four direct dyes, viz. NOVASOL Direct Black, NOVASOL Direct Blue GL, NOVASOL Direct Red 2BL and NOVASOL Direct Flavin, by Agaricus bitorqus A66 was investigated. Among the four dyes tested, Agaricus bitorqus A66 showed better performance on the decolorization (77.42%) of NOVASOL Direct Black as compared to other dyes on the fourth day of incubation. Various process parameters like pH, temperature, incubation time, carbon and nitrogen supplements and C/N ratios were optimized to achieve maximum decolorization of NOVASOL Direct Black by Agaricus bitorqus A66. The effect of redox mediators like ABTS, veratryl alcohol, MnSO4, guaiacol, etc. on enzyme activity and dye decolorization was also investigated. The process optimization resulted into enhanced dye decolorization and enzyme activity. Maximum dye decolorization (99.68%) and high lignin peroxidase activity (855 IU/mL) was achieved only in 5 h. Lignin peroxidase (LiP), which was found to be the major enzyme secreted by Agaricus bitorqus A66.

The thermal-diffusion and diffusion-thermo effects on heat and mass transfer by magnetohydrodynamic (MHD) mixed convection stagnation-point flow of a power-law non-Newtonian fluid towards a stretching surface in the presence of a magnetic field, thermal radiation and homogenous chemical reaction effects have been studied. A suitable set of dimensionless variables is used and similar equations governing the problem are obtained. The resulting equations have the property that they reduce to various special cases previously considered in the literature. An adequate implicit tri-diagonal finite-difference scheme is employed for the numerical solution of the obtained equations. Various comparisons with previously published work are performed and the results are found to be in excellent agreement. Representative results for the velocity, temperature, and concentration profiles as well as the local skin-friction coefficient, the local Nusselt number and the local Sherwood number illustrating the influence of the magnetic parameter, power-law fluid index, mixed convection parameter, concentration to thermal buoyancy ratio, thermal radiation, chemical reaction, and Dufour and Soret numbers are presented and discussed.

Cadmium and zinc removal from aqueous solution by polyelectrolyte enhanced ultrafiltration (PEUF) process was investigated using poly(acrylic acid) (PAA) with an average molecular weight of 100 kDa. The ultrafiltration studies were carried out using a tangential cell system equipped with 10.000 MWCO regenerated cellulose. Several parameters, such as transmembrane pressure, PAA concentration, pH and ionic strength, have been optimized to improve the retention of the metal ions. The removal of Cd2+ and Zn2+ is more than 96% and 94%, respectively, when each ion was studied separately. The study of pH effect on the cadmium and zinc recovery reveals retentions almost around 85% and 78% respectively at pH 5. Selectivity was studied using a solution containing the two metal ions. It was found that zinc retention decreases compared to single metal solutions, which is more significant in the case of cadmium ions.

In this work, a computational fluid dynamics analysis (CFD) employing the Eulerian two-fluid model was carried out with the aim to understand the distribution process and to determine the wetting efficiency of the primary tray distributor (perforated plate) of a trickle bed reactor (TBR) under several operating conditions. The overall inlet geometry was considered, and the small holes of the perforated plate were modeled by sinks (drains) and sources, employing CFD and experimental models to obtain the hole discharge flow coefficients. The influence of the ceramic-ball bed above the catalyst bed was considered by a suitable correlation to estimate liquid distribution inside it.Results showed that because of the scarce liquid sloshing above the tray, little difference on liquid flow rate through the tray holes was found. Due to the really low inlet mass flow rate of gas, it has negligible influence on liquid behavior, which drops through holes slowly without spraying. Thus, the ceramic-ball bed above the catalyst bed is exclusively wetted in a small area under the tray holes. Although the ceramic-ball bed improves liquid distribution, which guarantees a minimum liquid volume fraction at all places, significant differences on the liquid mass flow rate across the top of the catalyst bed were found. Additional causes of low efficiency in TBR like the well-known fouling vulnerability of perforated-plate trays and unevenness were analyzed. For the first, two simple modifications were proposed to improve tray performance: reducing the amount of gas chimneys to only one and adding additional drip points and replacing the tray holes by short risers in order to avoid plugging.

The adsorption and flotation of soluble crude protein from dairy products by colloidal gas aphrons (CGA) were studied. Selected process variables that were studied with respect to protein recovery include volume ratio between crude protein and CGA, stirring speed in the separation vessel, and contact time and surfactant concentration used to generate CGA. Cetyltrimethylammonium bromide (CTAB) in the buffered solution was used as the surfactant. It was found that only volume ratio between crude protein and CGA and surfactant concentration significantly influenced the protein recovery. The protein recovery achieved via its adsorption onto CGA surface and its subsequent flotation can be adequately modeled using Langmuir kinetics.

In this study, the equilibrium and the kinetics of Bovine Serum Albumin (BSA) adsorption onto metal oxides such as alumina (Al2O3) and zirconia (ZrO2) were investigated in a batch reactor. The effects of pH and temperature to adsorption rate and the equilibrium were studied. The equilibrium process was described by the Langmuir or the Freundlich isotherm models. The maximum adsorption capacity (Q0) was found as 81.6 mg/g at pH 5 and 20°C for Al2O3 and 26 mg/g at pH 4 and 40°C for ZrO2, respectively. The protein adsorption capacity for ZrO2 increased with increasing pH and temperature, while the protein adsorption capacity of Al2O3 increased with increasing pH and decreasing temperature. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. The rate kinetics of BSA adsorption onto Al2O3 and ZrO2 at all pH and temperatures were best fitted with the pseudo-first-order kinetic model. The electrostatic interactions of BSA with the metal oxide surface were found to be higher at pH 5 for Al2O3 and pH 4 for ZrO2.

Microchannels, which have a wide surface area per unit volume, have the potential for use in efficient chemical synthesis, separation and analysis. When microchannels are applied to mass transfer operations between immiscible liquids, a layered laminar flow is preferable because the two liquids can be spontaneously separated at the outlets. In this study, the flow of a water-octane system in a horizontal microchannel 200 ?m in width and 200 ?m in depth was simulated using CFD software. The simulation suggested that a stable layered flow was realized when the contact angle of octane on the hydrophobic inner walls was smaller than ca. 60 degrees and when that on the hydrophilic inner walls was larger than ca. 120 degrees irrespective of the inlet planes into which water and octane were introduced. To fulfill these requirements, PMMA plates were modified using five procedures, and the contact angles of one of the liquids were determined in the presence of the counterpart liquid. Measurement of the contact angles was carried out by lateral observation (in the case of spherical cap drops) and the fringe pattern of laser interference (in the case of thin films). When the two liquids coexisted, a combination of modification with 1-octadecanethiol for hydrophobicity and coating with TiO2 for hydrophilicity was the most workable of the treatments tested. Microchannels modified by this combination were then fabricated. When either water or octane were introduced into the hydrophilic and hydrophobic half-sections, respectively, a stable two-phase layered flow was obtained.

Biodiesel is one of the most famous alternative petroleum diesel fuels. It is a clean fuel that causes less pollution than petroleum diesel does. To produce biodiesel by the conventional process, a biodiesel plant requires at least a reactor and a distillation column. Therefore, this work focuses on a feasibility study of using reactive distillation (RD), the combination of a reactor with a distillation column in one unit, to produce biodiesel from palm oil. The hypothesis of using RD is to reduce the amount of excess alcohol in the feed stream bringing its stoichiometric ratio close to that of oil. That causes less energy to be required for the methanol recovery process. Aspen Plus 2006 has been used to simulate this process. The kinetic constants of the conventional process need to be modified for the RD process. The preliminary results show a 4:1 molar ratio of methanol to oil, and the reboiler temperature at 150°C produces a 97.36 %(wt) methyl ester in 5.6 minutes. It can be concluded that using the RD process is more efficient and more feasible than using the conventional process to produce biodiesel from palm oil.

This work deals with a real environmental problem related with milk whey wastewater. Even if a high depuration degree can be achieved using aerobic biological processes, the final effluent does not accomplish the legal regulation for disposal. In this context, we studied the application of ozone oxidation after an activated sludge treatment in order to obtain an effluent suitable to be discharged into the natural water courses. Even if the pH increase improved single ozonation efficiency, the treated wastewater was not yet able to be disposed of. The introduction of hydrogen peroxide at low concentrations enhanced the ozone action over the pollutants, and this combination led to residual water within the environmental law conditions to be released on the surroundings. Furthermore, heterogeneous catalytic ozonation over Mn-Ce-O 70/30 (prepared in our laboratory) and the commercial N-150 catalyst (Fe2O3-MnOx) was very efficient on the wastewater depuration. Nevertheless, the high amount of carbon adsorbed on the recovered catalysts disable the industrial implementation of this technology.

Tannery led chromium toxicity is one of the major threats to public health in developing countries, where most of the hides are treated at local cottage industry level and chromium liquor is released without detoxification. In this connection, the present study was conducted to develop a reliable cost effective fungal-based biosorbent for chromium removal. Six strains of Aspergillus niger were isolated from various environmental conditions and assessed for chromium tolerance. Biosorption potentials of two different biomass, i.e., live and dead, of selected Aspergillus niger ZH2 was investigated as a function of appropriate equilibrium time, pH, temperature, concentration of biosorbent and adsorbate in batch system. The chromium uptake by these biomasses was quantitatively evaluated using Langmuir and Freundlich isotherms. In order to determine the best fit isotherm, three error analysis methods were used to evaluate the data: correlation coefficient, residual root mean square error and chi-square test. Maximum adsorption capacity (qmax) was calculated to be 322.60 and 12.00 mg/g for live and dead biomass respectively. Application of Langmuir isotherm showed that live biomass was more favorable (95% CI, 1.053-8.718) than dead biomass in removing chromium and thus can serve as better biosorbent.

Oxidative degradation of Brilliant Red X–3B has been carried out using Fenton’s reagent both in the dark and in the presence of visible light. The degradation rate was increased using Fenton’s process in the order of Dark < Visible < UV. At pH 3.3, the maximum Fenton and photo-Fenton effect were noticed. At [H2O2]/[Fe(III)] = 3.5, a steady Fenton effect was observed. Meanwhile, at [H2O2]/[Fe(III)] = 0.7, Fenton process in the dark minimized the photo effect. The degradation rate was positively influenced by the temperature where the activation energy of degradation was evaluated as 36.98 kJ mol-1.

Titanium dioxide (TiO2) film with urchin-like nanostructures has been successfully fabricated without invoking any catalyst or template on silicon substrate. The morphological features characterized by FE-SEM showed that TiO2 film consisted of numerous sharply tipped micro-daggers with lengths of several micrometers and diameters of about 20 nm. X-ray diffraction pattern (XRD) shows that all diffraction peaks can be indexed to the rutile phase of TiO2. The water repelling characteristics of the film were measured by Contact Angle Meter as well as snapshots taken from a Hitachi camera. This measurement shows the water has a contact angle (CA) of about 151.2°. The above measurements indicate that the TiO2 film has super-hydrophobic property.

Biodegradation experiments were carried out using the fungal strain Phanerochate chrysosporium MTCC 787 to reduce the chemical oxygen demand (COD) and the color of the textile effluent containing Procion Blue 2G.In degradation, biochemical oxidation (BO) was coupled with an electro oxidation (EO) process before and during sequence. The integrated process was carried out in three cycles for the effluents containing 10 mL and 20 mL of inoculum (two different culture concentrations) in aerobic conditions. The overall COD reduction was 90.6% and 92.4%, respectively, and complete color removal was achieved at the end of sequential integrated oxidation process. The treated effluent was subjected to photo-oxidation to remove the microbes so that the water can be recycled after the removal of total dissolved solids (TDS).The experimental results showed that the integrated BO with EO is a viable option to reduce COD and color of the dye solution containing the bio-recalcitrant reactive dye Procion Blue 2G using the fungal strain Phanerochate chrysosporium MTCC 787.

In this paper, we study the production of 1,3-propanediol in fed-batch culture with coupled feed of glycerol and alkali. On the basis of the numerical solution to an optimal control problem subjected to a multi-stage nonlinear dynamical system, we propose a realizable optimal feeding strategy. Correspondingly, an automatic control system is designed for the fermenter, which involves the designs of control circuit, software flow control and computer monitored control system. This contribution successfully achieves a goal of combining a mathematically theoretical analysis with an automatic control design in the laboratory.

A chemical reactor is designed and developed to synthesize silica nano-powders by oxidation of tetraethyl orthosilicate (TEOS) using a three-port diffusion flame burner. Nano-silica powders were successfully synthesized. The particle size of the silica powders were confirmed by AFM and TEM techniques. Scanning electron microscopy (SEM) reveals that as-synthesized silica powders are in agglomerated condition. Phase analysis using XRD shows that the nano-silica in as-prepared condition is in amorphous form. However, during subsequent heat-treatment, it becomes crystalline.

In this research, wet hydrolysis of polyethylene terephthalate (PET), as used in beverage bottles, has been carried out using sulfuric acid. The hydrolysis reaction has been investigated in a laboratory glass reactor, provided with an anchor mixer and a digital torque meter. The hydrodynamics of viscous liquid in stirred reactor has also been studied by computational fluid dynamics simulation. The results of simulations give the operational conditions for optimum mixing into the designed agitated reactor. In the stirred reactor, the used chopped PET pieces were degraded into its constituent monomers, terephthalate acid (TPA) and ethylene glycol, in an acidic medium. The hydrolysis of product was characterized by (FT-IR) spectroscopy, while the efficiency of TPA production was measured by (UV-Vis) spectrophotometer. The effects of different parameters such as temperature, acid concentration and reaction time on PET degradation have been investigated. The experimental results show that the optimum reaction condition occurred while the sulfuric acid to used PET ratio is 4:1 at a reaction temperature of 90°C and reaction time of five hours.

This paper aims to investigate the sorption of Astrazon yellow (A.Y.) onto sawdust (Aleppo pine tree), a forest waste as that acts as a low-cost adsorbent. In our experiments, the batch sorption is studied with respect to solute concentration, contact time, adsorbent dose, particle size and pH. The adsorption process attains equilibrium within 300 minutes. The extent of dye removal decreased with increasing particle size and increased with increasing contact time, adsorbent dose and pH. The equilibrium data were analysed by the Langmuir and Freundlich isotherms. The characteristic parameters for each isotherm were determined. By considering the experimental results and adsorption models applied in this study, it can be concluded that equilibrium data were represented well by the Langmuir isotherm equation. Maximum adsorption capacity calculated at 293K was 81.8 mg/g. Five kinetic models (pseudo-first order, pseudo-second order, fractional power, Elovich and intraparticle diffusion kinetic equations) were used to predict the adsorption rate constants. The kinetics of adsorption of the basic dye followed both Elovich and pseudo-second order kinetics, and intraparticle diffusion was not the sole rate-controlling step. The effective diffusion of Astrazon yellow in sawdust according to Boyd Model was 24.22 .10-12 m2/S. In order to reveal the adsorption characteristic of sawdust samples, SEM and FTIR spectra analyses were carried out. The results show that sawdust (Aleppo pine tree) can be an alternative low-cost adsorbent for removing cationic dyes from wastewater.

The problem of spray/droplets dynamics in a downstream decelerating boundary layer accompanied by evaporation and wall suction is treated analytically. A similarity approach is employed and explicit expressions are obtained for the distribution of the host-gas velocity and for the distribution of the liquid phase. Several options are considered in terms of evaporation, including the possibilities of constant evaporation in the lateral direction of the boundary layer and of evaporation dependent on proximity to the wall. The results reveal the possibility that, under certain conditions, the liquid phase concentration reaches an extremum inside the boundary layer domain, rather than at the wall or in the free stream.

Advanced oxidation processes have been investigated as a viable means of treatment for the degradation and removal of dye-containing effluents. In this work, the degradation of an azo dye, Eriochrome black, was studied using a novel photocatalytic reactor in which TiO2 is immobilized on a rotating corrugated drum. The degradation of the dye via the photocatalytic method was confirmed, and degradation rates were compared using different drum designs. Catalyst deactivation was observed, and this process of irreversibility was found to increase with increasing initial dye concentration in the water. A Langmuir-Hinshelwood kinetic analysis was applied, and it was found to agree well with the data in the initial parts of the reaction but diverged with increasing time. The discrepancy was thought to be due to the presence of unquantified reaction intermediates which may only be broken down slowly by the photocatalytic process.

Current biomass-to-energy technologies usually are not economically competitive compared with fossil fuel-based technologies. Therefore, further developments in bioenergy are still needed and new concepts such as “negative net CO2 emissions” that can improve the economics of biomass utilization are of great interest. Accordingly, an ODB-H2-WGS process integrated with CO2 capture, a fuel cell and an oxygen generator is proposed. The ODB-H2-WGS process can decarbonize biogas and simultaneously generate high-purity hydrogen. The ODB-H2-WGS process is illustrated by means of the case study in which three reactors are simulated, i.e. the oxyforming reactor, the HT-WGS reactor and the LT-WGS reactor. The results show that the ODB-H2-WGS process can produce a CO2-H2 mixture from which H2 is separated and the remaining CO2 is ready for compression and sequestration. The oxyforming reactor enables complete conversion of methane. CO is shifted in the HT-WGS and further in the LT-WGS reactors to its equilibrium concentration. The results reveal that the properly designed LT-WGS reactor is crucial for WGS reaction completion due to likely departure from the equilibrium conversion. Consequently, by using the ODB-H2-WGS process pure hydrogen is produced from renewable biogas with the maximal yield of 3.3176 H2:CH4 on molar basis.

Thermodynamic analysis of gasification with air, steam, and mixed air-steam was performed over rice husk to determine the optimum conditions (i.e., equivalence ratio (ER), steam to biomass ratio (SBR) and operating temperature) that can maximize the yield of hydrogen production with low energy consumption. It was found that for air gasification, H2 production is always less than CO production and considerably decreased with increasing ER. For steam gasification, the simulation revealed that H2 production is greater than CO, particularly at high SBR and low temperature; furthermore, H2 yield increased steadily with increasing temperature and SBR until reaching SBR of 3.5-4.0, then the effect of steam on H2 yield becomes less pronounced. As for the mixed steam/air gasification, H2 production yield increased with increasing SBR, but decreased dramatically with increasing ER (up to 0.4). Among these three operations, the highest H2 production yield can be achieved from the steam gasification with SBR of 4.0. Nevertheless, by considering the system efficiency, the combined air-steam gasification provided significant higher hydrogen production efficiency than the other two operations. The optimum condition for combined air-steam gasification can be achieved at 900°C with ER of 0.1 and SBR of 2.5, which provided the efficiency up to 66.5 percent.

Self-defined scalar method is developed to simulate the combustion process and soot yield of propane/air laminar diffusion flame by defining reaction components and intermediates as self-defined scalars in computational fluid dynamics’ (CFD) code Fluent. In the simulation, Casimir’s propane combustion mechanisms are adapted for detailed chemical reaction mechanisms of the combustion process, and 1st order reaction of soot formation by surface growth is used. The 1st order rate coefficient of the surface growth is obtained by using the Sunderland and Faeth method with experimental data on acetylene concentration, soot yield and particle size. Comparisons are made on acetylene profile and soot yield between simulated and experimental results.

The kinetic modeling of the photocatalytic degradation of formaldehyde — a major indoor pollutant — in air using an experimental catalytic wall continuous reactor is addressed. A stainless steel flat plate coated with titanium dioxide was placed within the reactor, over which flows an air stream with a known concentration of formaldehyde. The energy source for the ultraviolet radiation that initiates the degradation reactions is provided by a group of five black light lamps next to the reactor window. An analytical expression for the photocatalytic degradation of formaldehyde in air is proposed, based on published literature on accepted reaction mechanisms. Once the kinetic control regime for the reactor was determined, experiments were conducted by the variation of the three operating variables that influence the reaction rate: the inlet formaldehyde concentration, the relative humidity and the level of radiation. A non-linear expression resulting from the combination of a mass balance for formaldehyde and the rate expression were used to estimate the kinetic parameters. The photocatalytic oxidation process for the removal of formaldehyde in air proved to be feasible and efficient under the operating conditions analyzed.

In this work, an approach based on traveling wave phenomenon is implemented for finding exact solutions of MHD aligned flow of an incompressible second grade fluid. The partial differential equations (PDEs) are reduced to ordinary differential equations (ODEs) by using wave parameter. The methodology used in this work is independent of symmetry consideration and other restrictive assumption. Comparison is made with the results obtained previously.

The development of greener chemical processes is becoming more and more important because this approach moves towards sustainable methods and products, minimizing pollution and risks for human health and environment. In these perspectives, microwaves seem to fulfil these requirements; in this context, we have tested a novel method both for the synthesis of nanocatalysts and for thermal activation of catalytic reactions. Until now, microwave chemistry has been generally performed inside a closed metal cavity, i.e. a microwave oven, but this approach presents relevant drawbacks, in particular for large scale application. Recently, we have proposed a new, cheap, sustainable process for large scale preparation of nanocatalysts, overcoming the disadvantages of the current synthesis methods. This novel method has been successfully adopted for the preparation in situ of ruthenium, palladium and silver nanoparticles as colloids or on different supports. Our procedure is safe and cheap, enabling to obtain the utmost efficiency and control also for industrial application. The obtained nanocatalysts present small average diameters, good morphology and very narrow sizes distribution with an absolute reproducibility. The ruthenium nanocatalysts were tested in the selective hydrogenation of phenol to cyclohexanone and palladium nanocatalysts were tested in the selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde, and we obtained good performances in both reactions.

This paper aims to describe a simplified method to optimize the geometry of a solar thermochemical reactor. As a first step, this paper focuses on a purely thermal analysis. The chemical reaction is represented by a uniform heat sink inside the material. The heat transfer modes are radiation in the empty part (cavity) and conduction inside the reactive material. The aim is to find the optimal geometry of the reactor, by maximizing its efficiency, for a fixed value of the incident solar flux and of the total volume of the reactor. An analytical solution can be found thanks to some simplifying hypothesis. The influence of different operational parameters on the maximal efficiency and on the optimal shape is studied. A comparison between different reactor designs (cylindrical and cavity reactors) is shown. A 2D study, based on CFD software using a finite element method, allows for quantifying the effects of the simplifying assumptions. The constructal theory aims to optimize the internal structure of a system in order to provide easier access to its internal currents and increase the system efficiency. Thus, this study can be seen as the optimization of the elemental volume of the constructal approach. In a next step this optimization method will be used to optimize more complex reactor design, as for example, a honeycomb reactor obtained by the assembling of several cavities, in order to optimize a thermochemical reactor for hydrogen production or high temperature heat storage.

This paper concerns the cleaning of the hot gas produced by steam gasification of biomass in a fluidized bed. The cleaning takes place in a catalytic filter candle device placed directly in the freeboard of the bed. Such integration results in a compact processing unit and increased thermal efficiency; the result of the cleaning being carried out directly at the reactor outlet temperature. It thus lends itself to exploitation in distributed power generation systems utilizing renewable energy sources. Results are reported for runs performed in a bench scale fluidized bed steam gasifier fitted with a single full-size catalytic candle filter. Tar and particulates in the product gas were sampled in accord with technical specification CEN/TS 15439 with analysis by UV and fluorescence spectroscopy.

In this paper the association of different families of amphiphilic compounds in room temperature ionic liquids in micelles, vesicles and reverse microemulsions was demonstrated. First the formation of nonionic polyoxyethylene-type surfactant micelles in the ionic liquid 1-butyl-3-methyl-imidazolium tetrafluoroborate is clearly evidenced using tensiometry and dynamic light scattering measurements. Critical micellar concentrations, object sizes and aggregation numbers are given and compared to aqueous and formamide systems. Then, vesicular aggregation of glycerophospholipid DPPC in two ionic liquids bmimBF4 and emimNTf2 was evidenced. Lastly, the phase diagram and microstructure of the ternary system ionic liquid (benzylpyridinium bis(trifluoromethanesulfonyl) imide)/nonionic surfactant (octylphenol ethoxylate)/toluene were studied. Phase stability and small-angle neutron scattering data show the formation of ionic liquid-in-oil microemulsion droplets. These reverse microemulsions were used as nanoreactors to perform a Matsuda-Heck reaction. The reaction yields obtained were greater in microemulsions (67%) than in bulk IL (33%) highlighting a strong effect of confinement. The reactivity in these confined media led to promising results.

The kinetics of the acid hydrolysis of arabinogalactans (AG) was studied isothermally in a batch reactor. AG was hydrolyzed with hydrochloric acid and the main parameters established were the acid concentration (pH), temperature and AG concentration. The hydrolysis rate increased with the acid concentration (pH) and temperature. Complete hydrolysis of AG to arabinose and galactose was achieved at 90°C and pH 1 without any further degradation of the sugars. A first-order kinetic model including two simultaneous reactions for the formation of arabinose and galactose was successfully fitted to the experimental data. The rate constants and activation energies were calculated from the model. The decrease of the average molecular weight was also explained by the model.

Dimethyl ether (DME), which is an excellent green diesel-fuel alternate with excellent clean burning properties, is synthesized by dehydration of methanol over novel solid acid catalysts, which are synthesized following a direct hydrothermal route and using silicotungstic acid (STA) as the active compound. These mesoporous silicate structured catalysts have surface area values of 108-393 m2/g, depending upon their W/Si ratio. These catalysts showed very high methanol dehydration activity and also very high DME selectivity values, approaching 100%. The STA-SiO2 mesoporous nanocomposite catalyst having a W/Si atomic ratio of 0.33 showed the highest activity, with a DME selectivity over 99% and a methanol conversion over 60%, at 250°C and at a space time of 0.27 s.g.cm-3. Effects of W/Si atomic ratio, calcination temperature and the synthesis procedure on the catalytic performance of these novel mesoporous catalytic materials were investigated.

Gasification of glycerol waste which is a by-product from biodiesel production was carried out using LaNiO3 and LaCoO3 perovskite-type oxide catalysts in order to enhance the production of fuel gas while reducing tar from the process. This present work showed that perovskite-type oxide could be effectively applied for cracking of tar from gasification of glycerol waste. The perovskite catalysts were prepared by a sol-gel process using PVA. The optimum condition for synthesis of LaCoO3 and LaNiO3 perovskite oxide was identified when the precursor was mixed metal ion and PVA containing a mole ratio of metal ion to PVA monomer unit as 1:1 and dried at 120°C for 20 h. The synthesized materials were calcined at different temperature and the phases were characterized with x-ray diffraction (XRD). The results showed that the single crystalline phase of perovskite without intermediate phases was achieved from calcination at 800°C for LaNiO3 and only 700°C for LaCoO3. The specific surface areas of LaNiO3 and LaCoO3 catalysts were in the range of 2.46-5.55 m2/g and 3.13-7.68 m2/g, respectively. SEM micrographs of catalyst illustrated a fluffy and foam structure with porous network. Catalytic activity of the prepared samples was tested by conversion of glycerol waste in a fixed-bed reactor. The catalytic reaction was carried out at a temperature of 500-800°C. At high temperatures LaNiO3 appeared to be a superior catalyst which enhanced the production of favorable gaseous species. However further gas upgrading may be required because of low LHV and H2/CO ratios obtained at these conditions.

The interest in Indoor Air Quality (IAQ) has increased this past decade due to better knowledge of this kind of pollution. Recent studies have pointed out the Indoor Air Pollution (IAP) impact on health and associated costs. IAQ improvement can be achieved by removal of pollutant with adapted process. Numerous processes, as sorption or UV photocatalysis, have been studied for IAP treatment. However, IAP specificities, including high number of compounds with different physico-chemical properties at low concentrations, still limit process efficiencies. Competition between pollutants and process selectivity are also common limitations. Biofiltration is commonly used to treat effluents containing numerous compounds at low concentration in composting units or wastewater treatment plants. Moreover, since it uses waste as a filtration medium and avoids the addition of chemical products, biofiltration is a sustainable technology. In this study, biofilter performances for IAP treatment are evaluated. The biofilter is packed with compost, a natural medium which has a large range of microorganisms, good physical properties (water retention, pH) and contains nutrients. The model effluent contains 8 compounds (aldehyde, aromatic, chlorinated, inorganic...), at low concentration (sub-ppmv), chosen for their ubiquity in indoor air, their heterogeneous physical and chemical properties (solubility, vapor pressure, biodegradability) and their potential health risk due to chronic exposures. Biofilter performances were evaluated during 75 days in steady state. Three compounds, undecane, limonene and butyl acetate, could not be quantified during the study, removal efficiencies are close to 100 %. Butanol, formaldehyde and toluene were removed with efficiencies close to 100 % during the first 40 days. After this time, efficiency variations were observed and the removal efficiencies decreased to 55.5, 77.8 and 13.9 % for butanol, formaldehyde and toluene, respectively. The decrease of bed moisture content seems to be the main explanation for these phenomena. Removal efficiencies of 86.3 – 99.6 % were achieved for nitrogen dioxide. Only trichloroethylene, known as a not easily biodegradable compound, was not removed by the biofilter: only sorption and desorption phenomena were observed during this time for this compound. In these starvation conditions, biomass cannot grow and only a fraction of the biomass can be maintained in the biofilter. However, this non-negligible biomass fraction can have a biological activity and removes the different compounds contained in the model effluent.

In reactive extrusion, the extruder is used as a solvent-free continuous chemical reactor able to process highly viscous materials. The chemical transformation of biopolymers by reactive extrusion appears as a very promising technology. Although punctual applications in this field have already been achieved on a laboratory or pilot scale, the amount of work to carry out is still considerable. A wide range of reactions and raw materials may be explored, and the reactions achieved on a laboratory scale have to be optimized and transposed to an industrial scale. Process modelling and simulation constitute useful tools for process understanding, development, optimization and scale-up. Although reactive extrusion modelling has interested many authors, it still remains a challenge because of the complex geometry and the strong coupling between operating parameters, flow conditions, material rheological behavior and reaction kinetics. A steady-state mathematical model for a biopolymer oxidation process by reactive extrusion is here proposed. The model is based on a hybrid approach combining chemical engineering methods and simplified continuum mechanics laws. The combination of these two approaches enables to simplify the calculations related to chemical reactions while ensuring a predictive character. The flexible structure of the model enabled its implementation within a global process simulator. A method to minimize the amount of experimental data required for model parameter adjustment is also presented. The model was validated by experiments conducted on a semi-pilot corotating twin-screw extruder. Even if it may be refined, the model proposed already constitutes a useful tool for later research work dealing with the development, modelling and simulation of chemical reactions in corotating twin-screw extruders.

Glycerol waste from biodiesel production can be converted to syngas (CO+H2) via a thermochemical conversion process. In this study, microwave was used to initiate a glycerol conversion reaction in a specially fabricated quartz tube reactor with a silicon carbide bed as the microwave absorber. A nickel-based catalyst and steam were added to the reacting bed to enhance production of hydrogen. By adjusting the microwave power level from 110 to 880 watt (W), the reaction temperature of 500°C to more than 1400°C could be rapidly achieved within a few minutes, which is much faster than heating by conventional furnaces. The gasification reaction commenced by feeding raw material continuously through the hot silicon carbide bed at a rate of 1 g/min with the O2 to fuel ratio varying from 0-0.25. The overall time for each trial was 20-30 minutes including preheating of the bed material. In contrast to typical biomass gasification, char and tar yields were small in most runs. In general, glycerol waste yielded higher syngas when compared with pure glycerol conversion. Complete conversion to gas product may be achieved at a power level of 440W. The maximum syngas production from glycerol waste without a catalyst was more than 23.98 L over 20 min run at 660 W with 0.25 O2 to fuel ratio. Overall content of other hydrocarbon gases was around 3-28 vol.% depending on operating conditions and raw material. Lower heating values (LHV) of product gas for glycerol waste were much higher for runs at 1.0 L/min carrier gas flow, ranging from 3.75-17.64 MJ/m3 while relatively stable LHV of 1.96-5.88 were obtained from 2.0 L/min flow. The addition of a catalyst significantly increased gas production at lower wattage runs where overall conversions were comparable to those of higher wattage experiments without catalysts. The maximum total conversion and LHV were obtained from 1%Ni/SiC catalyst at a reaction temperature of 600°C (330W) and no external O2 with a gas product heating value of 9.18 MJ/m3 and 1.32 H2 to CO ratio. From these results, the novel microwave-induced heating technique can be considered as an efficient option for conversion of glycerol waste via the gasification process to acceptable quality syngas.

This work aims to develop new uses for sewage sludge, which is a byproduct of municipal wastewater treatment plants, by examining the calcination of this waste, the characterization of ashes is obtained, and its use to prepare desulfurant sorbents. Samples of sewage sludge were obtained from a local municipal wastewater treatment plant. This plant applies a pre-treatment followed by a biological treatment, where anaerobic digestion and centrifugation reduces the sludge. Three samples were characterized (in humidity, volatile and fixed solids content), dried, and ignited at two temperatures, 550 and 750°C. The composition of the ash obtained at both ignition temperatures was studied by x-ray fluorescent spectroscopy and the BET specific surface area of the two ashes and of the prepared sorbents was measured. Ash composition was similar for the two temperatures tested, where the components were Si, Ca, Al, Fe, P, S, Mg, K, Cl, Zn and Ti. BET specific surface area values indicate that the lower temperature of calcination produces ash with the highest SSA values (18 m2/g against near 10 m2/g). Preparation of desulfurant sorbents was carried out by mixing the ash with CaO or Ca(OH)2 at room temperature and different experimental conditions. The BET SSA of the prepared desulfurant sorbents showed higher values for the sorbents prepared with the ashes obtained at the lowest temperature. The behaviour of the ash and the prepared sorbents was tested in a fixed bed reactor at 58°C with a flue gas containing 5000 ppm of SO2 with a relative humidity of 55%. Results in the desulfurization process show that the calcium from the sludge seems more efficient than the calcium added as CaO or Ca(OH)2 to prepare the sorbents.

At Delft University of Technology theoretical and experimental research is carried out towards selective production of furfural from renewable biomass. Furfural is an interesting molecule that has been identified as a platform chemical for a multitude of chemical products and fuel (additives).Acidic biomass hydrolysis and subsequent dehydration of the obtained C5 sugar xylose leads to furfural. The reaction selectivity is a point of concern for reactor design, as furfural can further react to loss products. The residue of this process mainly consists of the remaining main biomass constituents, cellulose and lignin. Mineral matter is to a large extent extracted to the acid in the primary hydrolysis. This implies that the residue has the potential to be a better feedstock for thermo-chemical conversion, as e.g. alkali and chlorine species—now extracted—potentially cause different types of problems (slagging, fouling, agglomeration etc.).An interesting option for example might be to convert this improved feedstock into synthesis gas via a gasification process, which then needs to be conditioned and upgraded for the production of green transportation fuels. In this line, a new biorefinery generation is created, which selectively uses the hemi-cellulose part of biomass. An analysis is presented towards current (integrated) concepts for novel, improved furfural production process. This paper presents some current process concepts and a novel continuous process design.

The use of supercritical carbon dioxide technology for lipid processing has recently developed at the expense of traditional processes. For designing new processes the knowledge of thermophysical properties is a prerequisite. This work is focused on the characterization of physical and thermodynamic properties of CO2-cocoa butter (CB) saturated mixture. Measurements of density, volumetric expansion, viscosity and CO2 solubility were carried out on CB-rich phase at 313 and 353 K and pressures up to 40 MPa. The experimental techniques have previously been compared and validated. Density measurements of CB and CB saturated with CO2, were performed using the vibrating tube technology at pressures ranging from 0.1 to 25 MPa. Experimental values correlated well with the modified Tait equation. CO2 solubility measurements were coupled to those of density in the same pressures ranges. At 25 MPa, the solubility of CO2 is 31.4 % and 28.7 % at 313 and 353 K. Phase behaviour was investigated using a view cell in order to follow the expansion of the CB-rich phase with the rise in pressure. Volumetric expansion up to 47 % was measured and correlated to the CO2 solubility. Phase inversion was observed at 313 K and 40 MPa. Lastly, we developed an innovative falling ball viscometer for high pressure measurements. Viscosity measurements were carried out up to 25 MPa showing a viscosity reduction up to 90 % upon CO2 dissolution. These results were correlated with two empirical models. A new model here presented, was favourably compared with the Grunberg and Nissan model. All the experimental results are consistent with the available literature data for the CB-CO2 mixture and other fat systems. This work is a new contribution to the characterization of physical and thermodynamic behaviour of fats in contact with CO2 which is necessary to design supercritical fluid processes for fats processing.

Application of trickle-bed reactor and active carbon catalyst to catalytic wet air oxidation of phenolic pollutants is explored over a wide range of operating conditions. The study focuses on the assessment of key engineering aspects such as reactor start-up, gas-liquid flow directions and effects of temperature, pressure, phenol feed concentration and liquid flow rate on activity and stability performance of unsupported active carbon. Moreover, for analyzing the potential integration of CWAO as a pre-treatment in biological wastewater remediation, intermediate distribution and biodegradability enhancement of treated effluents are obtained from HPLC analysis and respirometry assays, respectively. Finally, since slow carbon burn-off is occurring at CWAO conditions, some promising options for improvement of catalyst stability are pointed out on both molecular (iron coating of active carbon) and reactor (periodic reactor operation) scale.

This work presents an experimental study of hydrodynamic behaviour and mass transfer performance of ceramic foam (SiC) as column packing. Voidage of the foam studied is of 91% with 640 m2/m3 specific area and 5 PPI. Hydrodynamics experiments are realised with air-water system in counter current in a 150 mm diameter column with a packing height of one meter. Parameters studied are pressure drop for dry and wet packing, flooding and liquid hold-up. Total reflux experiments with n-heptane/cyclohexane mixture were carried out in a distillation column at atmospheric pressure to study mass transfer by determination of HETP (Height Equivalent to Theoretical Plate). The performance in terms of pressure drop per unit height and flooding are quite lower in comparison with classical packings of distillation. The pressure drop obtained is about few millibars per meter (0-10 mbar.m-1) for F-Factor from the range of 0 to 1 and liquid superficial velocities from 1 to 10 m3m-2h-1. Liquid hold-up values, measured in the same range of flow, are in a range of 5 to 10%. The possible application of foam as a packing for distillation is so demonstrated.

The use of sunflower oil as an environmentally-friendly solvent was examined for the separation of penicillin G (Pen G) from a synthetic fermentation media to develop a cost-effective process. In order to evaluate this, equilibrium experiments were first carried out with solvent alone (sunflower oil/pegasol/tributyl phosphate) and then with the solvent containing dissolved Amberlite LA-2, an ionic carrier. The organic systems with the carrier gave better distribution of Pen G between the aqueous and organic phases. The values of the distribution coefficient were greater for tributyl phosphate (TBP) than the other solvents at the natural pH of Pen G. Sunflower oil gave a good distribution ratio and it can be recommended as an attractive option because of its low cost, minimal toxicity and moderate performance. The effectiveness of the carrier-sunflower oil (organic phase) was evaluated in a hollow-fiber membrane contactor by performing experiments with the organic phase on the shell side and the feed inside the fiber. With a small amount of carrier (approx. 5%) in the organic phase and at the natural pH of penicillin G, a good percentage extraction (approx. 40-45%) was achieved. The percentage extraction decreased (approx. 30-35%) when penicillin G was prepared in a synthetic fermentation media instead of pure aqueous media. These results are similar to those reported by many investigators; the main difference is that, in this report, an environmentally-friendly solvent was used instead of toxic solvents used in the literature, such as kerosene.

A polybenzimidazole supported Mo(VI) (PBI.Mo) catalyst has been prepared and characterised. The catalytic activities of the PBI.Mo catalyst in epoxidation of alkenes with tert-butyl hydroperoxide (TBHP) as an oxidant have been studied under different reaction conditions in a batch reactor. As alkene representatives we have chosen cyclohexene, limonene, ?-pinene and 1-octene (a less reactive terminal alkene). The order of reactivity of the alkenes was found to be: cyclohexene>limonene>?-pinene>1-octene. The stability of each polymer catalyst was assessed by recycling a sample in batch reaction using conditions that will form the basis of the continuous process. The loss of Mo from each support has been investigated by isolating any residue from the reaction supernatant solutions, following removal of the heterogeneous polymer catalyst, and then using the residues as potential catalysts in epoxidation reactions.

The catalytic potential of sludge based materials produced by steam or CO2 activation from non-treated dewatered raw sludge or dewatered mesophilic anaerobically digested sludge were tested in the oxidation of phenol. Batch and continuous experiments were conducted to assess activity and stability of these novel carbons in terms of phenol conversion, carbon burn-off and metal leaching. Overall, their catalytic activity can be considered satisfactory when compared to commercial carbons. However, further research on the preparation, activation and hardening of these sludge based materials is required to improve their thermal and mechanical stability and resistance to metal leaching during the catalytic wet air oxidation of phenol.

This study established a kinetic model of the thermal decomposition properties of hexanitrohexaazaisowurtzitane (CL-20) and cyclotetramethylene tetranitramine (HMX) using differential scanning calorimetry (DSC) and kinetic evaluation simulations. The goal was to analyze the thermokinetic parameters of CL-20 and HMX by DSC and then to compare thermal decomposition energy parameter simulations under various conditions using a kinetic model. The experimental results that were obtained depend strongly on the reliability of the applied kinetic model, which is essentially defined by the suitable selection of a mathematical model and the accuracy of the methods used in the kinetic evaluation. This study resulted in a quick and efficient procedure for obtaining information about the thermal decomposition characteristics and the reaction hazards of CL-20 and HMX. This procedure could be applied to develop inherently safer reaction designs under normal or extraordinary operating conditions.

The desorption of additives and polymer residues from materials (P) is of significant concern for a wide range of applications, including polymer ageing, off-odors, and the safety of materials in contact with food or water. With diffusion coefficients, partition coefficients between P and hydrogen-bonding liquids (L), denoted Ki,L/P for a solute i, are fundamental quantities to assess the loss of plastics constituents. For a polymer with a crystallinity c, they are defined as ln(Ki,L/P) - ln(1-c) =(uexi,P- uexi,L)/(kBT), where {uexi,k}k=L,P are the excess chemical potentials and where kB is the Boltzmann constant. Our ambition was to relate calculations of {uexi,k}k=L,P at an atomistic scale to measurable partition coefficients obtained for bulky solutes with different stiffness and shape, such as hindered phenolic antioxidants, n-alkanes and n-alcohols. For large solutes in dense and cohesive phases (P or L), promising computation techniques involve free energy perturbation and non-equilibrium methods, thermodynamic integration, and extended ensembles (Gibbs or osmotic ensembles). Because the free energy landscape of the coupled i+k system contains several minima and highly heterogeneous barriers, a low convergence is generally achieved. To overcome such complications, we calculated {uexi,,k}k=L,P at atomistic scale in the framework of the Flory-Huggins approximation. The main advantage is that the mixing energy for a wide range of conformers was derived from pairwise interactions and a continuous approximation of the packing of molecules without representing explicitly large molecular systems. The translational entropy in L was inferred from a mesoscopic representation of the liquid medium matching the radial distributions calculated by isothermal and isobaric molecular dynamics simulations. The corresponding predictions were satisfactory compared with 38 experimental Ki,L/P values between polyethylenes, polystyrene and different alcohols (isopropanol, ethanol).

Solar thermal pyrolysis of natural gas is studied for the co-production of hydrogen, a promising energy carrier, and Carbon Black, a high-value nano-material, with the bonus of zero CO2 emissions. A 10 kW multi-tubular solar reactor (SR10) based on the indirect heating concept was designed, constructed and tested. It is composed of an insulated cubic cavity receiver (20 cm side) that absorbs concentrated solar irradiation through a quartz window by a 9 cm-diameter aperture. The solar concentrating system is the 1 MW solar furnace of CNRS-PROMES laboratory. An argon-methane mixture flows inside four graphite tubular reaction zones each composed of two concentric tubes that are settled vertically inside the cavity. Experimental runs mainly showed the key influence of the residence time and temperature on the reaction extent. Since SR10 design presented a weak recovery of carbon black in the filter, a single tube configuration was tested with an external plasma heating source. Complete methane conversion and hydrogen yield beyond 80% were achieved at 2073K. Hydrogen and carbon mass balances showed that C2H2 intermediates affect drastically the carbon black production yield: about half of the initial carbon content in the CH4 was found as C2H2 in the outlet gas. Nevertheless, the carbon black recovery in the filtering device was improved with this new configuration. Data are extrapolated to predict the possible hydrogen and carbon production for a future 50 kW solar reactor. The expected production was estimated to be about 2.47 Nm3/h H2 and 386 g/h carbon black for 1.47 Nm3/h of CH4 injected.

This paper presents a Photovoltaic (PV) simulation system powering a reverse osmosis (RO) desalination unit with no energy recovery device (ERD). The simulation is carried out using commercial software, Transient System Simulation (TRNSYS®). The PV system consists on solar panels (Siemens SM55) with rated power of 55 W, connected to a storage battery via DC-DC charge controller. The load of this system is a pump, which provides the RO system with feed water. The RO unit is composed of one Filmtec spiral wound membrane. Simulation results for fresh water production showed that with a continuous feed of 1.5 m3h-1, a total capacity production of 110 m3 per year can be achieved. The effect of the main parameters in desalinated water production capacity showed that with the increase of the raw water feed flow and the PV surface, the monthly fresh water production increases. They also showed that with the increase of raw water salinity, the fresh water production decreases. This work is validated with literature experimental results.

Wet agglomeration of granular materials is widely carried out in many industrial fields, such as the pharmaceutical and food industries. This process must be optimized in terms of yields and quality of the final product. A lot of studies have shown that agglomeration occurs under capillary, viscous and frictional forces and can be divided into four steps: nucleation, consolidation, growth and rupture. This general description of agglomeration does not take into account the simultaneous changes of agglomerates size, texture and saturation degree with respect to the increase in water content. The aim of this work is to propose a description of the agglomeration based on experimental observations and to take into account the aforementioned aspects to propose a model. In this study, experiments are carried out on kaolin in a low shear mixer for various operating conditions: three speeds of blade rotation, two wetting modes. The evolution of agglomerates granulometric and textural parameters is taken into account by image analysis and immersion in paraffin, respectively. This study makes it possible to highlight an increase in agglomerates size associated with a solid volume fraction reduction when there is an increase in water content. A power law connects solid volume fraction and median diameter of agglomerates making it possible to identify a fractal growth process between the grain and pasty-like scale. This well-know approach in colloidal aggregation is new in the powder agglomeration field. Fractal dimension defined this way is mainly affected by the drop size generated during wetting. These experiments highlight the weak influence of the other process parameters tested. For a wetting mode, an equation leading to the direct determination of the desired size of agglomerates with water content is proposed. Applied to agglomeration, fractal morphogenesis should become a potential tool in product engineering.

Many kinds of solids (e.g., biomass, thermoplastic and coal) thermally decompose according to similar types of kinetic pathways. They usually include a first step giving rise to more or less stable solid or liquid species followed by competitive reactions with formation of the final products (solids, vapours, and/or gases). In order to be extended to several types of solids, the present pyrolysis model relies on an original dimensionless Lagrangian approach. Mathematical equations of mass and heat balances are written in the assumptions that non-volatiles products form distinct layers which are separated by each other by moving interfaces that propagate towards the inner parts of the sample. The conditions required to apply this Lagrangian approach to solid thermal decomposition are discussed. The time evolution of pyrolysis products and sample internal temperature profiles are obtained by numerical solving of equations written in a reduced form. The first results of simulations performed in a large range of dimensionless parameters values (thermal Thiele, Biot and thermicity criteria) are reported. It is pointed out that variations of reduced masses as a function of reduced time significantly depend on operating conditions (particularly thermal Thiele and Biot numbers). The results of the model are finally compared to experimental data reported in the literature for cellulose fast pyrolysis. The agreement is quite good considering the uncertainties with which the physicochemical parameters are known from the literature.

Solubility, which defines the liquid /solid equilibrium, is a key parameter to control a crystallization process. This work is focused on the effects of pH, temperature and impurities on the aqueous solubility of an Active Pharmaceutical Ingredient (API).As the API is a weak acid (pKa = 3.7), its solubility increases with the pH. On the basis of the experimental curve of solubility, a model was defined to fit the evolution of the solubility as a function of pH. In the case of this compound, studies revealed a weak influence of the temperature in comparison with the pH. So, the solubility of the compound is slightly impacted by the temperature.Some experiments were carried out in order to compare the solubility of the API, at the same pH and temperature, for different concentrations of impurities found in the process. The results revealed a solubility increase in presence of acetic acid and a high solubility decrease in presence of sodium chloride. By carrying out experiments on common ions salts, the anion chloride Cl- has been identified as the cause of the solubility decrease.

The recovery of waste heat generated by many processes is one of the measures to reduce energy consumption. Heat pump is a machine which upgrades waste heat to make it useful. This study focuses on the development of an Absorption Demixing Heat Transformer (ADHT), a new type of Absorption Heat Transformer (AHT). An ADHT, using a working mixture exhibiting a miscibility gap at low temperature, can use low temperature heat to produce useful thermal energy at a higher temperature. The distillation column used to separate the components of the working mixture used in classical AHT is replaced by a settler where the separation is energetically free. The aim of this study is the cycle and working mixture optimization to find suitable working mixtures for an industrial use (targeted temperature lift (?Ti) ~40°C). In previous studies, the machine was operated successfully with the n-heptane/N,N dimethyl formamide (DMF) mixture, but has not led to a significant temperature lift (less than 8°C). A simulation code, written in FORTRAN 95, is developed to evaluate the performance of ADHT (temperature lift and thermal yield). This code includes a simplified thermodynamic model to represent the properties (enthalpy, equilibrium phase, etc.) of the mixture. The influence on the performances of operating parameters (column feed ratio and number of theoretical stages, etc.) is studied. The main parameters affecting the performance of ADHT are identified. The influence on the performances of each individual thermo-physical property of the mixture components (heat capacity, enthalpy of vaporization, etc.) is also studied. Key properties are identified including the enthalpy of vaporisation of components. A pilot ADHT unit will be constructed in order to prove the reliability of the machine.

The aim of this work is to prepare wound dressing hydrogels permitting (i) to cure chronicle pathologies; (ii) to remove unsuitable odors coming from healing. Thus, chitosan, a natural polymer with biological properties, and activated carbon (AC), a well-known adsorbent, are mixed within a composite hydrogel. To get a suitable porous structure for healing, the vapor induced phase separation process (VIPS) is used. It permits to slow down mass transfers kinetics compared to other elaboration processes such as the wet process. Hence, a better control of the final porous matrix is reached throughout the elaboration process.In this work, the mass transfers occurring through the elaboration of the composites were studied thanks to gravimetric measurements carried out during the VIPS process. Results showed there were two main steps in the gelation process. A weight intake, due to an ammonia flux allowing the gelation to happen, was followed by a weight loss, mainly controlled by a water outtake. This second part could be compared to a slow drying in smooth conditions. Gelation with a color indicator was also performed, which provided complementary experimental information on mass transfers barrier.A modeling of mass transfers mechanisms occurring during the gel elaboration is presented to get an overview of limiting phenomena leading to the final composite structures. It involves a coupling between chemical reactions, external mass transfers and internal diffusion within the polymeric matrix. Results show that internal diffusion is the main barrier to gelation.To qualify the gel structure, drying kinetics were compared on the elaborated gels. Whatever the gel, the drying kinetics were globally the same and could be divided into three steps. Considering the process used and this result, it was believed that the matrixes prepared were homogeneous and rather symmetric. They could constitute the first layer of wound dressings.

The hydrogen world consumption should increase significantly to progressively replace hydrocarbons. Due to its high power density, nuclear reactor should take an important place in this production. This paper focuses on the hydrogen production by thermochemical cycle using the heat available at 900°C of a new generation nuclear reactor. The chosen thermochemical cycle for this study is the iodine-sulphur thermochemical cycle water splitting.The process flowsheet under consideration has high total energy consumption. It has also many local energy needs unevenly distributed over a wide temperature range. The raw distribution of this energy gives a hydrogen production efficiency of 14.0%. To improve this, the proposed coupling is built using an energy distribution network with a coolant to meet the safety requirements. In this simple case, the efficiency of hydrogen production comes to 21.9%. By integrating a heat pump into the energy distribution network, the efficiency of production increases to 42.0%. The exergetic efficiency, increases from 59.3% to 85.8%.

The transport of large quantities of natural gas (NG) is carried out by pipeline network systems across long distances. Pipeline network systems include one or several compressor stations which compensate for pressure drops. A typical network today might consist of thousands of pipes, dozens of stations, and many other devices, such as valves and regulators. Inside each station, there can be several groups of compressor units of various vintages that were installed as the capacity of the system expanded. The compressor stations typically consume about 3 to 5% of the transported gas. It is estimated that the global optimization of operations can save considerably the fuel consumed by the stations. Hence, the problem of minimizing fuel cost is of great importance. This study presents a mathematical formulation for NG transport through pipelines and compressors by considering the mass and energy balance equations on the basic elements of a didactic network from the literature. First, a deterministic optimization procedure is implemented. The objective of this formulation is the fuel minimization problem in the compressor stations for a fixed gas mass flow delivery. A second example is devoted to the simultaneous consideration of gas mass flow delivery maximization and fuel consumption minimization. In that case, two procedures are compared: a genetic algorithm coupled with a Newton-Raphson procedure and the scalarization method of ?-constraint. In both monobjective and biobjective cases, a study of carbon dioxide (CO2) emissions is carried out. The Pareto front deduced from the biobjective optimization can be used either for identifying the minimum and maximum network capacity in terms of CO2 emissions and mass flow delivery or for a given mass flow delivery for determining the minimal CO2 emissions from an appropriate operating of the compressor stations.

In the present work, a drop tube reactor (DTR) and a horizontal tubular reactor (HTR) were used to study the pyrolysis behaviour of beech wood particles of different sizes under the conditions encountered in industrial fluidized bed gasifiers, namely high external heat flux (105 – 106 W.m-2) and high temperature (800 – 1000°C). The influence of the reactor temperature (800 and 950°C), of particle size (from 350 µm to 6 mm), and of gas residence time (from 1 to 10 s) were examined. Under the explored conditions, when pyrolysis is finished, more than 80 wt.% of virgin wood is converted into gas and less than 13 wt.% remains in solid. In the gas phase, CO is the main gaseous product (50 wt.% of virgin wood), followed by H2 (molar ratios of H2/CO are between 0.35 to 0.55), H2O, CO2 and CH4. Species C2H2, C2H4, C2H6 and C6H6 are present in much lower amounts. The increase of temperature increases the rate of solid devolatilization and favours the cracking reactions of hydrocarbons. The increase of particle size increases the required time for completing pyrolysis. Meanwhile, the results obtained at 950°C show that the final products distribution at the end of pyrolysis is almost the same for the particles between 350 and 800 µm. The increase of the particle size from 800 µm to 6 mm seems to have some influence on the final products distribution. The gas phase reactions mainly change the yields of light hydrocarbons and H2: the increase of gas residence time favours the cracking reactions of hydrocarbons and thus leads to a higher H2 yield.

Solid particles and tars are among the non-desirable products of synthesis gas produced during biomass gasification. Removal of fly ashes is necessary in order to comply with emission limits as well as avoid their deposition in downstream units. Condensation of tars, on the other side, can cause clogging. A catalytic hot gas filter can remove both solids and tars, when operating at temperatures as high as 850°C. Catalytic hot gas filter elements are under development in order to solve this issue.A lab-scale filtration unit has been designed and constructed at Delft University of Technology. The unit contains one ceramic hot gas filter candle which is made of a SiC porous structure coated with a mullite membrane. The integration of a Nickel-based catalyst layer allows the dual function of particle filtration and tar cracking. The filter vessel is part of a set-up that is equipped with a tar evaporator and a pre-heater, both located upstream of the filter unit.This paper presents the results of the first set of experimental tests that have been performed with this unit. A dust-free model gas was used and consisted of a mixture of CO (14%), CO2 (14%), H2 (7%), CH4 (5%), and varying concentrations of N2 (30, 40, 50%) and H2O (30, 20, 10%). Naphthalene (varying concentrations up to 9 g/Nm3) was adopted as model compound in order to study the catalytic conversion of heavier hydrocarbon species to H2. A gas face velocity of 2.5 cm/s and 3 cm/s was selected for tests performed at atmospheric conditions and at operating temperatures varying between 700 °C and 850 °C. The pressure drop through the filter candle was continuously monitored during the process. The gas composition was measured upstream and downstream of the filter unit by means of an on-line micro-GC, while naphthalene concentration was attained with the SPA method.The following findings were obtained: higher naphthalene conversion with increasing temperatures and better conversion at any temperature with lower concentrations. Tests at 850°C and 30 vol% H2O produced a conversion of 99.4% with 2.5 g/Nm3 while 98.5% with 7.8 g/Nm3. Experiments with higher steam content showed higher conversion values. Methane concentration was also affected thus indicating that reforming reactions took place as well. Low toluene concentration was detected as a product of the reactions while no benzene was identified.

Tin(II) chloride dihydrate (SnCl2.2H2O) has been an efficient Lewis acid catalyst in the ethanolysis of saturated and saturated free fatty acids (FFA). This compound is stable under aerobic conditions and it has shown to be as active as the mineral acid H2SO4, a common acid catalyst in the conventional production of biodiesel. The carbon chain length of FFA and the fatty acid/alcohol molar ratio were parameters of investigation herein in association with the yield and reaction rate of free fatty ethyl esters (FAEE) formation. The efficiency of the process of recovery of SnCl2 also has been evaluated. It was verfified that the catalytic activity of the recovered SnCl2 has remained unaltered in successive reactions with oleic acid. The residual content of catalyst in the biodiesel was determinated by spectrophotometry of atomic absorption. The use of SnCl2 has advantages in comparison with mineral acid catalysts. For instance, the absence of corrosion in the reaction vessel as well as the unnecessary neutralization of the catalyst after the reaction finishes. The results in this work put forward the SnCl2 as a promising catalyst for the production of biodiesel.

One of the most promising renewable fuels proposed as an alternative to fossil fuels is biodiesel. The competitive potential of biodiesel is limited by the price of vegetable oils, which strongly influences the final price of biofuels. An appropriate planning and design of the whole production process, from the seed to the biodiesel end product, is essential in order to contain the fallout of energy inefficiencies in the high price of the end product. This study focuses on the characteristics of the production process currently used to produce biodiesel.Refined vegetable oil can be converted into biodiesel by means of a great variety of techniques and technologies, many of which are still not suitable for application on an industrial scale. The solution of greatest interest is homogeneous alkaline transesterification with KOH and methanol. Even when dealing with this type of conversion, it is impossible to establish a universal pattern to describe the conversion or purification stages because there are various possible solutions that make each system different from another. When we look more closely at the state of the art in industrial biodiesel production plants, we also encounter the potential problems introduced by the type and characteristics of the raw materials.Comparing some of the reference solutions that have inspired numerous installations, an optimization analysis was conducted using ASPENPLUS 2006, for the modeling of the process, and modeFRONTIER 4.1 for the optimization procedure. The optimization analysis was carried out using a multi-objective genetic algorithm optimization in order to define the configuration of the main parameters that guarantee the best trade-off between the maximization of the purity of some important compounds and the minimization of energy requirements in the process. The results of this analysis were Pareto frontiers that identify a family of configurations which define the best trade-off between the objectives. Using the Pareto frontiers we then selected the configuration that requires the minimum energy consumption. Among these optimal configurations there is one which guarantees the lowest specific energy consumption while all the optimal configurations obtained respected the requirements of EN 14214, in terms of biodiesel quality.

Pyrolysis converts biomass such as agricultural and forestry waste into bio-oil, preserving some chemicals while creating other, new ones. Nicotine, a chemical present in tobacco leaves and a known pesticide, was found to remain intact during pyrolysis. As expected, insecticidal properties were observed for tobacco bio-oil. Pesticide characteristics of tobacco bio-oil have been observed on the Colorado potato beetle (CPB), a pest currently resistant to all major insecticides, as well as a few bacteria and fungi that do not currently respond well to chemical treatment. Unexpectedly, nicotine-free fractions of the bio-oil were also found to be highly lethal to the beetles and successful at inhibiting the growth of select microorganisms. Through GC-MS, it was found that the active, nicotine-free fractions were rich in phenolics, chemicals likely created from lignin during pyrolysis. While bio-oils in general are known to contain phenolic chemicals, such as cresols, to our best knowledge, quantitative analysis has not been performed to determine if these chemicals are solely responsible for the observed pesticide activities. Based on GC-MS results, ten of the most abundant chemicals, eight of which were phenolic chemicals, were identified and examined through bio-assays. A mixture of these chemicals at the concentration levels found in the bio-oil did not account for the bio-oil activity towards the microorganisms. Tobacco bio-oil may have potential as a pesticide, however, further analyses using liquid chromatography is necessary to identify the remaining active chemicals.

The present work is focused on the aqueous-phase reforming of ethylene glycol at 500 K. The influence of the system pressure (27 to 36 bar) and the catalyst weight/ethylene glycol flow rate ratio has been studied using a Pt/Al2O3 research catalyst. A comparison of the latter with a Ni/Al coprecipitated catalyst showed a significant influence on hydrogen and alkane selectivities.

A characterization study has been performed of the French regional resources that may be used in Biomass-to-Liquid plants based on gasification in entrained-flow reactor. It is based on about 90 representative samples of wood chips from forestry, Short Rotation Coppice (SRC) and Short Rotation Forestry (SRF) and of agricultural biomass, including straws and energy crops. Results show that there is not much variability in properties inside the different families. The majority of properties do not seem to be problematical for the process. However, some properties may be questionable: (i) wood chips size distribution, with many small particles ( below 2 mm) and very large particles (above 70 mm), (ii) bulk density, which is very low in agricultural products (about 100 kg.m-3), (iii) sulphur, fluorine and chlorine contents, which are high, especially chlorine in agricultural straws (1000-8000 mg/kg) (iv) other impurities amounts, such as Ni and B, which are in relatively high amounts in some samples (v) ash content, which is high in SRC/SRF (3 wmf%) and very high in most agricultural raw materials (5 wmf%). Based on these statements, first conclusions on the suitability between feedstock and process may be drawn. Wood chips from forestry appear as the most suitable resource for the process and should be the first resource to be used in industrial plants. SRC/SRF also seem quite suitable for the process and may be seen as a short-term alternative. Agricultural raw materials seem to be more problematical and may be seen as a mid-term option.

The emerging biofuel industry demands large amount of biomass feedstock. Although commercial ethanol has been produced from primary biomass sources such as corns, the global food crisis caused by the use of primary biomass has been raised. Thus, lignocellulosic biomass, known as second generation of biomass, has become a promising source for ethanol production. However, the more complex structure requires more advance technology. MSW with more than 60% of biodegradable composition, as one of the promising biomass sources has the potential benefits of replacing primary biomass and preventing environment from MSW pollution.In this paper, three major biodegradable municipal solid waste (BMSW) components: kitchen organic waste (KOW), green organic waste (GOW) and paper and card waste (PCW), are classified and characterised according to substrate composition, cellulose crystallinity, bulk density and particle size. The substrate composition indicates how much cellulose, lignin, hermicellulose each model waste has. The cellulose content shows the potential glucose/ethanol product yield. Other chemical composition such as lignin and hemicellulose indicates how easy of each model waste can be converted. These contents are also important information when selecting pretreatment methods and conversion process conditions in the following steps.Based on the comprehensive understanding of biomass structures and compositions, studies look into the effects of substrate properties (such crystallinity, presence of lignin and cellulose content on process performances during enzymatic hydrolysis adsorption. Results indicated how the adsorption process is affected by the substrate properties. This provides understanding of the role of substrate properties during enzyme-cellulose adsorption.

1,1 Diethoxy butane was produced carrying out the reaction between ethanol and butanal in a batch stirred reactor using Amberlyst cation-exchange resins as catalyst. The kinetics of this reaction was studied working at different temperatures, feed compositions and catalyst type and loadings. Due to thermodynamic limitations, maximum conversions are quite low for kinetically acceptable temperatures. That is why the kinetic information gathered has been used to develop a model for reactive distillation, which has predicted promising results.

There are various kinds of stresses during the process of ethanol fermentation and more inhibitory factors are produced when lignocelluloses hydrolysate is used as the substrate. The pretreatment of lignocelluloses biomass causes the increase in the amount of acids and thus the decrease in pH. Low-molecular weight aliphatic acids, furaldehydes and a broad range of aromatic compounds are produced during the pretreatment process. They are the inhibitors for the ethanol producers, e.g. Saccharomyces cerevisiae. Furthermore, besides glucose, lignocellulose hydrolysate contains other sugars, such as xylose, arabinose, galactose and mannose etc., among which xylose is taking the major proportion. Stress tolerance and xylose utilization are therefore essential for Saccharomyces cerevisiae strains to get high-efficiency fermentation and high-yield ethanol production from lignocellulosic materials. In this study, a few laboratory and industrial Saccharomyces cerevisiae strains were selected for the evaluation of their potentials in pH tolerance, inhibitor resistance, temperature and ethanol tolerance, and xylose resistance. The results revealed that strains ATCC 96581 and ATCC 24860 are the most stress tolerant S. cerevisiae strains for ethanol fermentation. Such strains will be improved for inhibitor resistance and xylose utilization in the future by metabolic engineering and directed evolution.

From escalating global concern over the exhaustion of non-renewable energy sources comes an imperative need for the use of renewable resources. Biomass pyrolysis has emerged as a very promising renewable alternative for fuel and chemical production. Previous work has shown that the most effective biomass pyrolysis processes require a careful control of temperature and residence times, and downer reactors appear to be the best technology to achieve such goals. Ongoing research at the Institute for Chemicals and Fuels from Alternative Resources (ICFAR) has led to the development of a new downer reactor design for the pyrolysis of biomass feedstock. However, this process requires a gas-solid separator that achieves a minimum spread of the gas residence time distribution – i.e., as near to plug flow as possible.As a result, a novel integrated gas-solid inertial separator has been designed for implementation in the downer reactor. This new separator combines both primary separation and solids stripping within the same device. This is intended to decrease the product vapor residence time and to reduce the severity of vapor overcracking compared to other fast separation methods. The gas-solid separation section of the new device features a uniflow configuration and a vertical, axial entry with either swirl vanes or a deflector cone.In the current study, various geometry configurations and operating conditions were tested for their effect on separation efficiency and pressure drop. A 70 mm-diameter separator was tested under cold flow modeling conditions using silica sand, glass beads or FCC catalyst particles as solid material. The sand, glass beads and FCC particles had Sauter mean diameters of 200 ?m, 63 ?m and 43 ?m, respectively. Air was used in all cases with a gas inlet velocity varying from 0.95 to 13 m/s and solid loadings ranging between 0.075 and 19 wt/wt. The separation length was adjusted from 0.1 to 2 separator diameters.Initial cold flow experiments using silica sand revealed that the separator performance was influenced greatly by the separator geometry. The measured separation efficiency was greater using flow deflector blades (i.e. swirl vanes) than all tested cone deflectors. Solids recovery in excess of 99.99% was achieved. Particle collection efficiency decreased steadily as the separation length increased, but was in general not as strongly affected by solid loadings or gas inlet velocity. Experimental cold testing of glass beads in air gave typical efficiencies above 98.50%. Recovery of the lighter and smaller FCC catalyst was also very high, with a minimum measured efficiency of 98.80%.