Iranian Journal of Chemical Engineering (IJChE)

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 A study on coke deposition and coking inhibitors during naphtha pyrolysis was made in a jet stirred reactor system. This system is noted for its simple structure, easy alteration of operating parameters, small volumes of feedstock used for pyrolysis, high accuracy of coke formation measurements, and short operating cycle. It is also particularly suitable for identifring coking inhibitors over a wide range of conditions. The effect of the addition of CS2, DMS, DMDS and Disulfideoil in the naphtha feed was investigated. It was found that for a given concentration of sulfa. in the feed, the asymptotic coking rate decreases in the order: Dimethyl disulfide > Disulfideoil > Dimethyl sulfide > Carbon disulfide. 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 small amounts of Ni, Cr, and Fe elements. Based on our results, this paper aims to provide a closer insight into the coking problem in industrial steam crackers.