Ethylene Cracking Modeling And Application Research Based On Kinetics Optimization

The rapid development of ethylene derivative industries, like energy,materials and automobile, leads to increasing demand of ethylene. Serving asthe cornerstone of chemical industry, ethylene could be produced by severalmethods. And thermal cracking is one of the most mature and widely appliedtechnologies. Equipped with cracking furnace, many kinds of feedstock couldbe cracked into ethylene.Simulation of ethylene cracking includes reaction kinetics modeling andprocess modeling, while the former one is the most fundamental. Amongresearches and achivements, molecular reaction kinetics model is bothaccurate and handleable. In1985, Kumar and Kunzru proposed a completemodel. According to their experiments and analyses, secondary reactions areindependent of feedstock. However, selectivity coefficients and kineticsparameters in the primary reaction need to be optimized with different oilproperties, because they affect product yields a lot.This paper focuses on the application improvement of Kumar model, andhas adopted a chaos optimization algorithm for adjustment of kinetics model parameters. It has simple and easy structure, fast convergence rate and hasrealized accurate modeling of19kinds of naphtha. The algorithm reaches agood compromise between atoms balance and minimal yield errors. It alsotakes into consideration minor adjustment of the reaction activation energyand frequency factor.Sequential Quadratic Planning-Chaos Particle Swarm Optimization(SQP-CPSO) algorithm has also got satisfactory parameters for ethylenecracking models. PSO is applied for global search of parameters, while SQP isfor local searching. And chaos mapping is added to guarantee the variety ofparticles, able to escape local minima. Both applied algorithms have their ownadvantages, able to establish accurate ethylene cracking model for naphthaswith different properties.At last, a modeling software of ethylene cracking based on Kumarkinetics is developed. This software has advantages of operability,visualization and extensibility. It could adapt to modeling of different naphtha,different types of crackers with double-passes. Therefore, Kumar kineticsmodel is extended to a wider application scope with relatively high modelingprecision. Moreover, elementary research and experiments about yieldsprediction of new oil on the basis of Monte-Carlo Simulation are conducted.