Volume 16, Issue 12 -

Is it possible to miniaturize a chemical plant? Some strategies, such as the process intensification, sustain that the advancements in equipment and production techniques could substantially decrease the equipment size/production capacity ratio, energy consumption and waste generation, resulting in more economic and sustainable operations and consequently reducing the chemical plant size. However, large reductions of equipment volume represent a major challenge for the conventional technologies. In this context, Microfluidics represents a promising technology in the field of system miniaturization. Accordingly, the present research evaluated the concept of process intensification and its relationship with Microfluidics. Initially, the definition and the classification of process intensification were described, following by the explanation of the Microfluidics, highlighting scale-up strategies and examples using miniaturized systems. Afterward, a methodology for miniaturized devices development for process intensification using numerical simulations was shown. Finally, the conclusions are exposed.

We herein report the results of our investigation into the modes of catalytic partial oxidation (CPOX) of liquid fuels and air mixtures to yield endothermic (endo) gas on a pilot-scale installation containing ~ 0.45 cm 3 catalytic bed. This endothermic gas serves as a protective atmosphere in thermochemical steel treatment processes. Seven liquid hydrocarbons (LHs) are investigated, namely isooctane, 91 RON (research octane number) and 95 RON gasoline, diesel, kerosene, jet fuel, and naphtha. All experiments are performed using our previously developed reactor, where the reactions of natural gas/air mixtures were previously studied. In the present study, we report that the LH conversion products reached an equilibrium state similar to that of methane and natural gas conversion with an atomic C/O ratio of ~ 1.0 in the mixture. Furthermore, working regimes between 850 and 950 °C are examined as typical reaction conditions for industrial endo gas generators, and in all cases, the required gas quality is achieved. However, we found that gasoline and diesel are the most suitable LH feedstock for endo gas generation.

Gas-liquid dispersion characteristics were experimentally investigated by measuring largest Lyapunov exponent ( LLE ), relative power demand ( RPD ), and local gas holdup in a stirred tank with rigid impellers, rigid-flexible impellers, and punched rigid-flexible impellers. Results showed that punched rigid-flexible impeller could enhance the value of LLE , namely, the chaotic mixing degree of gas-liquid system compared with rigid impeller and rigid-flexible impeller. RPD for punched rigid-flexible impeller was higher than that for rigid impeller and rigid-flexible impeller. The local gas holdup of punched rigid-flexible impeller system was higher than those of rigid impeller system and rigid-flexible impeller system at the same P g,m . In addition, a long flexible connection piece length could improve the chaotic mixing degree, RPD , and local gas holdup. The aperture diameter of 8 mm and free area ratio of 12 % of punched rigid-flexible impeller were particularly suitable for the gas-liquid dispersion process in this work.

Detailed understanding the particle mixing and segregation dynamic is essential in successfully designing and reasonably operating multicomponent fluidized bed. In this work, a novel fluorescent tracer technique combining image processing method has been used to investigate the mixing and segregation behavior in a binary fluidized bed with wide size distributions. The particle number percentage in each layer for different gas velocities is obtained by an image processing method. Fluidization, mixing and segregation behavior has been discussed in terms of bed pressure drop, gas velocity and mixing index. Different types of binary particle systems, including the jetsam and the flotsam-rich system, are analyzed and compared. The mixing indexes at different minimum fluidization velocities are also analyzed and compared with other work. The results show that the theoretical minimum fluidization velocity calculated from the bed pressure drop cannot represent the whole fluidization for a wide size distribution binary particle system. The effect of a wide size distribution is an inflection point in the mixing index curve. There is also a dead region in the bottom of the bed that consists of particles with large size and a low degree of sphericity. The particles in the dead region are extraordinarily difficult to fluidize and should be considered in the design of fluidized beds in industrial applications.

The study represents the development of nano zinc oxide catalyst coated with alumina by co-precipitation method for dehydrogenation reaction studies. The catalyst characterization was done by transmission electron microscopy (TEM), X-Ray diffraction (XRD), BET surface analyzer and scanning electron microscopy (SEM). The reaction chosen was dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) with a variation of different operating parameters such as temperature, partial pressure, reactant flow rate. The conversion was investigated by varying catalyst amount and size. The role of reaction rate on various operating parameters like temperature, the partial pressure of reactant, catalyst to feed ratio has been explored. The rate of the reaction along with order and rate constant have been calculated. The activation energy was calculated from Arrhenius law to depict the nature and efficiency of the reaction chosen.

Ni–Mo ore is a multi-metal complex and unique mineral resource that exists as a black shale. This ore contains more than 4 wt% Mo and at least 2 wt% Ni. Economic value is associated with deriving products from Ni–Mo ore that contains amorphous colloidal sulfides and that is highly active. Under low-temperature hydrothermal conditions (water at 120 °C or more) and in excess oxygen, amorphous sulfides are oxidized easily to metal-sulfate forms, which leads to nickel and molybdenum dissolution. In this study, the effects of agitation speed, temperature, oxygen partial pressure and particle size on the rate of nickel leaching were investigated. The leaching rate was nearly independent of agitation speed above 400 rpm and increased with a decrease in particle size. A temperature increase to 150 °C contributed significantly to the nickel leaching rate. Oxygen pressure influences nickel leaching, with an oxygen pressure of between 0.5 MPa and 0.7 MPa providing the greatest effect. The pressure-leaching behavior of nickel was fitted to a shrinking-core kinetic model. The mathematical analyses indicates that the dissolution process is chemical-reaction controlled during early dissolution, with an activation energy of 42.68 kJ/mol, and the reaction order with respect to the oxygen partial pressure was 0.79. Up to nearly 70 % nickel was dissolved into solution, and product layers of molybdenum and iron oxide were formed on the surface of the Ni–Mo ore particles, which prevented further nickel dissolution. Thereafter, nickel leaching was controlled by liquid-film diffusion, with an activation energy of 11.01 kJ/mol.

The purpose of current study is to deliberate the effect of chemical reaction on 3D flow and heat transfer of an MHD nanofluid in the vicinity of plate containing gyrotactic microorganism over a elastic surface. Influence of uniform heat source/sink on temparature transfer has been considerd. The governing standard nonlinear system of equalities is resolved numerically via Runge-Kutta  method of  45th order based shooting scheme. Role of substantial parameters on flow fields as well as on the, heat, mass and microorganism transportation rates are determined and discussed through ploted graphs.

Industrial gas-liquid processes such as oxidation, hydrogenation, Fischer-Trospch synthesis, liquid-phase methanol synthesis, and nuclear fission are exothermic in nature; the reactor of choice for such processes is, therefore, a bubble column equipped with heat exchanging internals. In addition to maintaining the desired process temperature, the heat exchanging vertical tube internals are used to control flow structures and liquid back mixing. The present work reports the experimentally measured gas hold-up, mean liquid velocity and liquid phase turbulent kinetic energy, using the Radioactive Particle Tracking (RPT) technique, in a 120 mm diameter bubble column equipped with dense vertical tube internals covering 23 % of the total cross-sectional area of the column. The effect of superficial gas velocity (44–265 mm/s) on gas hold-up, mean liquid velocity and turbulent kinetic energy is presented and discussed. It has been inferred from the experimental results that the vertical tube internal located at the center of the column plays a vital role in affecting the hydrodynamics when compared to the conventional internal configurations reported in the literature. For the chosen dense internal configuration, the cross-sectional distribution of the gas holdup, mean liquid velocity and turbulent kinetic energy show asymmetry for all the superficial gas velocities investigated. The overall gas holdup and the liquid turbulence increases with an increase in the superficial gas velocity. The strong liquid circulation velocities have been seen upon the insertion of the dense internals.

The Moringa oleifera leaf is an important source worldwide with a high nutritional value and functions in food and feed that may also treat a myriad of ailments but the leaf has low organoleptic properties and digestibility. To overcome this shortcoming, a novel Aspergillus niger was isolated from the Moringa leaf material. The fungal strain grows well on moist Moringa leaves and requires no additives. After performing a single factor test for temperature, moisture, inoculation size, and fermentation, the optimized condition was determined by using a response surface method, followed by a small-scale production test. The pleasant, sweet smelling aroma in the fermented leaves was then generated, supplementing than its native repulsive smell. The protein content and digestibility of the leaves increased by 23.4 % and 54.4 %, respectively; the direct-fed microbes reached up to 1.99 × 10 9 CFU per gram of fermented freeze-dried Moringa leaves. Digestive lignocellulolytic enzymes were substantially produced with 2.97 ± 0.24 U.g −1 of filter paper activity and 564.9 ± 37.4 U.g −1 of xylanase activity. Moreover, some functional components, such as flavonoids and γ-Aminobutyric acid content, were also significantly increased compared to that of the unfermented leaves. In conclusion, the feed quality and digestibility of Moringa oleifera leaves were greatly improved via solid-state fermentation by Aspergillus niger . Fermented Moringa oleifera can be used as a potentially high- quality feed alternative for the animal industry.

In the present study, Eucalyptus camaldulensis bark/maghemite composite (ECMC) was used for potential application as a low-cost adsorbent for the removal of Cr(VI) from aqueous solution. The structural characterization, morphology and elemental analysis of ECMC were performed by Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray (EDX) and X-ray Diffraction (XRD). The effects of various independent parameters, contact time, initial Cr(VI) concentration, temperature, pH, and adsorption were investigated. It was found that the adsorption capacity of ECMC increases with increasing Cr(VI) concentration and temperature. The optimum pH was found to be 2 for the removal of Cr(VI) by ECMC. The adsorption capacity was found to be 70.1 mg/g with 0.1 g ECMC at pH 2 and 30 °C. Additionally, 10 and 50 mg/L Cr(VI) were removed from 100 mL aqueous solution by 0.1 g ECMC with 99 % and 93.46 % removal efficiencies, respectively. Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Jovanovic, Smith, Koble Korringen, Vieth-Sladek and Sips Isotherm Models were applied to the experimental data to understand the adsorption mechanism better. The Freundlich Isotherm Model described the adsorption process better (R 2 = 0.991) among the other isotherms studied.