Iranian Journal of Chemical Engineering (IJChE)

Abstract A series of experiments were carried out by mixture of methanol and water as feed of the methanol to propylene (MTP) process in temperature range of 623-823 K. The H-ZSM5 catalyst with the Si/Al ratio of 200 was applied for carrying out the experiments. A novel lumped kinetic scheme was proposed for methanol to propylene (MTP) process. The reactor was mathematically modeled by assumptions of being isothermal, fixed bed, plug flow and the hybrid genetic algorithm was applied for estimating the kinetic parameters. The temperature dependency of the kinetic parameters was determined,
using the modified Arrhenius relation. A good agreement was observed between the experimental and the calculated data. Effect of temperature on propylene and ethylene selectivity was investigated. It was found that the propylene selectivity increases with temperature until 773.15 K, but after that it decreases.

Abstract This paper reports the result of CFD simulation of catalytic oxidation of benzene on monolithic catalyst. The geometries ofthe catalyst and reactor were designed in Gambit software and simulation of catalytic oxidation was carried out in fluent 6.2. Results of simulation showed excellent agreement with the experimental data. This study confirmed the accuracy of the used model in this simulation (Mars van Krevelen). Furthermore, CFD made it possible to obtain a more accurate view ofheat transfer and fluid flow. This study confirmed CFD is the best tool for study offluid regime and heat transfer and especially, concentration of species, and surface deposition along the reactor in the chemical process.

Abstract The effectiveness of binary mixtures of phosphorus and sulfur compounds as coke inhibitors for naphtha pyrolysis has been studied. As both phosphorus and sulfur compounds proved to be promising coke inhibitors, runs were made with mixtures of these compounds. The coke deposited was significantly lower when phosphor was used together with sulfur. Also, the effect of the addition of K₂CO₃ and K₂CO₃ in the naphtha feed was investigated. It was found that the addition of Na₂CO₃ and K₂CO₃ reduced the coke formation. Scanning electron microscope (SEM) was used for the
microstructure of deposited coke and energy dispersive X-Ray spectroscopy (EDAX) for the surface elemental composition of coke formed on the surface of stainless steel coupons. It was found that in the presence of inhibitors, deposited coke has a porous structure and so small amounts of Ni , Cr , and Fe elements.

Abstract An industrial ethane thermal cracking reactor was modeled assuming a molecular mechanism for the reaction kinetics coupled with material, energy, and momentum balances of the reactant-product flow along the reactor. To carry out the multi-objective optimization for two objectives such as conversion and ethylene selectivity, the elitist non-dominated sorting genetic algorithm was used. The Pareto optimum set was obtained successfully and finally the effect of the decision variable was discussed.
 
 

Abstract SHAHAB is a PC- based simulator developed by Olefin Research Group (ORG), with the simultaneous simulation of the reactor, the firebox, the convection section and the transfer line exchanger in steam Cracking units. The reaction mechanism of thermal cracking of hydrocarbons is generally accepted as free-radical chain reactions. Using a rigorous kinetic model, a complete reaction network for representing the decomposition of hydrocarbon feedstocks has been developed and used for simulation of thermal hydrocarbon crackers. Taking into account the kinetics of coke formation, SHAHAB provides a detailed understanding of product, temperature and pressure distribution, coke thickness profile, reactor run length, fuel consumption and the amount of steam generated.