Band 16, Heft 9 -

Pigging techniques are widely used in the oil and gas industry. The unsteady motion of the PIG in an undulating pipe section during the pigging process after a water pressure test affects the stable operation of the pipeline and also causes a pipe rupture accident in serious cases. First, an experimental study was conducted to investigate the pigging process of air–water two phase pipe flows, and the PIG reverse movement and hydraulic pulse phenomenon were observed. Subsequently, a hydraulic transient model of the pigging process after a water pressure test was established in a dual-grid system. The model combined mass and motion equations of gas and liquid and PIG dynamic equations, considered three types of PIG motion states, namely positive movement, reverse movement and still, and used the method of characteristics to solve the equations. The model exhibits the ability for PIG tracing and hydraulic pulse prediction. It can be used to obtain the position and speed of the PIG. Finally, the field data and simulation results were compared, and the results indicated that they are essentially identical. This verified the accuracy of the model that is established in this study and the reliability of computed results and provided a reliable and effective theoretical basis for the development of field pigging plans.

The combined impact of solar radiation, chemical reaction, Joule heating, viscous dissipation and magnetic field on flow of an electrically conducting nanofluid over a convectively heated stretching sheet embedded in a saturated porous medium is simulated. By using appropriate similarity transformation, the governing nonlinear equations are converted into ODEs and numerical shooting technique with (RK45) method is employed to tackle the problem. The effects of various thermo-physical parameters on the entire flow structure with heat and mass transfer are presented graphically and discussed quantitatively. Special cases of our results are benchmarked with some of those obtained earlier in the literature and are found to be in excellent agreement. It is found that both the temperature and surface concentration gradients are increasing functions of the non-Darcy porous medium parameter. One describing result is the incident solar radiation absorption and its transmission into the working nanofluid by convection.

In this study, ethylene furnace modeling is carried out by ethane pyrolysis (thermal cracking or hydrocracking) method in Arya Sasol Petrochemical Company (ninth olefin unit, Assaluyeh, Iran), which includes the solution of kinetic equations and transfer phenomena, by the forward finite difference method in the MATLAB. Due to study and compare coke formation, a specific time period has been selected in equal segments and equations have been solved. It means that in a length segment of coil (Δz), momentum, energy as well as mass equations are solved, then the amount of precipitated coke in each length segment is achieved. With new efficient coil diameter calculating all mentioned approach will be repeated for next time segment. The results of this model have been compared with actual data and deviation has been reported. It was found that modeling approach is more capable to define the parameters of coke formation equations. The model has a good agreement between the values of prediction and experimental of in most cases.

The main theme of this paper is to investigate entropy generation analysis for unsteady three-dimensional flow of viscous (Newtonian) fluid between two horizontal parallel plates. Lower plate is porous and stretching while upper plate squeezed downward. Further effects of nonlinear thermal radiation, viscous dissipation, heat source/sink and activation energy are accounted. Entropy generation rate calculated in terms of thermal radiation, fluid diffusion and fluid friction. Transformations procedure used lead to reduction of PDE’s into ordinary ones. Built-in-Shooting technique is used for the computational analysis. Impacts of different flow variables on temperature, velocity, concentration, volumetric entropy generation and Bejan number are discussed and presented through graphs. Temperature and concentration gradient are discussed numerically. It is examined from obtained results that velocity of liquid particle decays through larger estimation of squeezing parameter. It is also examined that temperature distribution enhances for higher estimation of radiative heat flux. Moreover temperature and concentration gradient increase for larger squeezing parameter.

In many chemical engineering processes, a chemical reaction between a foreign mass and the fluid does occur. These processes find relevance in polymer production, oxidation of solid materials, ceramics or glassware manufacturing, tubular reactors, food processing, and synthesis of ceramic materials. Therefore, an exploration of homogeneous first-order chemical reaction effects on heat and mass transfer along with entropy analysis of Jeffrey liquid flow towards a stretched isothermal porous sheet is performed. Fluid is conducting electrically in the company of transverse magnetic field. Variations in heat and mass transfer mechanisms are accounted in the presence of viscous dissipation, heat source/sink and cross-diffusion aspects. The partial differential equations system governing the heat transfer of Jeffery liquid is reformed to the ordinary differential system through relevant transformations. Numerical solutions based on Runge-Kutta shooting method are obtained for the subsequent nonlinear problem. A parametric exploration is conducted to reveal the tendency of the solutions. The present study reveals that the Lorentz force due to magnetism can be used as a key parameter to control the flow fields. Entropy number is larger for higher values of Deborah and Brinkman numbers. It is also established that the concentration species field and its layer thickness of the Jeffery liquid decreases for a stronger chemical reaction aspect. To comprehend the legitimacy of numerical results a comparison with the existing results is made in this exploration and alleged an admirable agreement.

In this paper, a continuous flat plate photoreactor with ZnO coating was studied in the photodegradation of methylene blue. The structural properties of catalyst were characterized by means of X-ray diffraction, Field emission scanning electron microscopy (FESEM), and energy dispersive X-ray (EDX). The XRD results indicate that high crystalline ZnO particles with average size of 13.5 nm were coated on the glass plate. The thickness of ZnO layer was 39.67 μm and the coating was uniform and crack free. The EDX showed clear border between glass and ZnO layer which confirmed no material transfer between glass and ZnO layer during thermal treatment. The influence of reactor parameters such as the slope of the glass plate, number of UV lamps, distance between lamp and ZnO coated glass plate and flow rate of wastewater was investigated using optimal custom design which is a subset of response surface methodology (RSM). The results indicated that the maximum photodegradation of methylene blue was achieved under the following conditions: plate slope of 9, 3 UVA lamps, 12 ml/s wastewater flow rate and 10 cm distance between lamp and glass plate. The response of surface methodology at optimum conditions was 65.05% while experimental value was 64.66%, showing good agreement between the experimental values and those predicted by the models, with relatively small errors which were only 0.64. The kinetic study was also performed for methylene blue photodegradation at optimum conditions.

The catalytic process of ethylene oxychlorination can be split into two steps,uiz.ethylenechlorination with the reduction of cupric chloride and reoxidation of the cuprous chloride by hydrogen chloride and oxygen. The transient process of 1,2-dichloroethane formation was observed by selected ion chromatography using a mass spectrometer. While the reaction exhibited first-order kinetics in regard to the concentration of cupric chloride, the dependency on ethylene concentration was interpreted by a Wachi & Yousuke and Carrubba mechanism. Optimal performance was achieved by impregnating ea. 5 wt % of copper into y-alumina powder and 64% of the copper contained in the alumina powder contributed to the formation of 1,2-dichloroethane.this study, constant adverse reactions were calculated due to the experimental data obtained from Abadan Petrochemical Unit and the speed equation of Wachi was modified. The reaction occurs at three phases of bubble, cloud, and emulsion and by increasing temperature and input gas velocity and keeping all the other parameters constant in several steps, the substrate was investigated and the conversion of ethylene and gross value for each test were calculated. Thus, with the determination of kinetic and dynamic parameters, the proper mathematical model was chosen and using this model, the conversion percent of ethylene was calculated and its actual amount and the percentage of error were calculated and compared based on information obtained from Abadan Petrochemical reactor under different conditions.

In the present work, hydrogenation of biomass derived 5-hydroxymethylfurfural (HMF) into fuel additive 2,5-dimethylfuran (DMF) is studied over Cu-Co/Al 2 O 3 catalyst. The influence of various operating parameters such as temperature, pressure, catalyst amount, time and HMF concentration on the conversion HMF to DMF was optimized using well known Taguchi method as statistical tool. According to Taguchi method, under optimum reaction conditions viz. temperature 220 °C, pressure 30 bar, reaction time 6 h, catalyst loading 0.5 g, and HMF concentration of 0.2 wt%, maximum DMF yield (87 %) was recorded. Analysis of variance suggested that temperature and pressure are the most influencing factor. Mechanistic study suggested that DMF can be obtained via C = O hydrogenation over Cu metal due to preferential adsorption of HMF on Cu metal which further undergoes acid catalyzed hydrogenolysis and resulted DMF. The initial rates of reaction HMF to BHMF varied linearly with hydrogen pressure at different temperatures, catalysts loading, and reactant substrate concentration. These observations indicate first order kinetics for HMF disappearance. According to power-law model, the order with respect to HMF was found to be 0.9. The experimental data could also be explained using Langmuir-Hinshelwood kinetics. A competitive hydrogen with dissociative adsorption on catalysts surface and surface reaction as the rate-controlling step provided the best fit of the experimental data.

The Fenton process has been widely studied in the treatment of wastewater but unfortunately this process can only work under acidic pH conditions. To overcome these disadvantages, the Fenton modified by adding chelating agents such as oxalic acid (Ferrioxalate complex (Fe(III)Ox) since its high solubility in aqueous media can broaden the available pH range of the Fenton reaction to near neutral pH. In this study, The photooxidation efficiencies of 3-methylphenol (3MP) catalyzed by Fe(III) and oxalic acid was investigated. The results show that the photodegradation Of 3MP is slow in the presence of Fe(III) or oxalic acid alone. However, it is markedly enhanced when Fe(III)Ox complex coexist. The concentration of the complex is optimized to the ratio ([Fe(III)Ox] = 3/12). Fe(III)Ox plays a positive role in the photo-Fenton system, especially at higher pH = 5.5. Oxygen is essential to the formation of oxidative species and, as a consequence, for the pollutant degradation. Additionally, the use of tertio-butanol as a scavenger confirmed the intervention of . OH in the 3MP photodegradation. 3MP degradation mechanisms have been elucidated and photoproducts are identified by comparison with authentic products. To get closer to the environmental conditions, the effect of main elements present naturally in the aquatic ecosystem such as humic substances and bicarbonates was examined. The photodegradation of 3MP through Fe(III)Ox system under solar light was significantly accelerated in comparison with artificial irradiation at 365 nm. Measuring chemical oxygen demand (COD) leads to mineralization which decreases the toxicity of 3MP solution. This work also demonstrates that this system is an encouraging method for the treatment of organic pollutants in the natural environment.

Biomass is an attractive target in process development for the emerging renewable resources based bio-refinery industry. Due to the ample range of application of acrylic acid, its production through bio-route received more awareness in scientific fraternity. In this view, an attempted was made to study the reactive extraction of acrylic acid with aliquat 336 in rice bran oil. Moreover, Box-Behnken matrix was employed to corroborate the effects of process variables viz. concentration of acrylic acid [C AA ] aq , concentration of aliquat 336 [C R4N + Cl ], and temperature on the extraction efficiency (η%). In physical extraction, average extraction efficiency was found in the order as: 43.55 > 35.36 > 29.14 at 303 K, 323 K, and 343 K respectively in rice bran oil. The correlation coefficient, R 2 = 0.988 % indicates the appropriateness of proposed model to predict the extraction efficiency in terms of independent variables, and the predicted values were found in close agreement with that of experimental results. Further, R 2 (Pred) = 0.806 is in reasonable agreement with the R 2 (Adj) = 0.972. The optimum conditions for extraction of acrylic acid using aliquat 336 as an extractant in rice bran oil are [C AA ] aq = 0.0.5 (mol/kg); [C R4N + Cl ] = 1.98 (mol/kg); temperature = 323 K and the model predicted extraction efficiency 77.5 % was found to be an excellent fit with the experimental value 75 %. Further, number of theoretical stages was found to be 3 and S/F ratio 0.247.