A CASE-STUDY FOR REACTOR NETWORK SYNTHESIS - THE VINYL-CHLORIDE PROCESS

A key objective of the integrated reactor network synthesis approach i s the development of waste minimizing process flowsheets (Lakshmanan a nd Biegler, 1994). With increasing environmental concerns in process d esign, there is a particularly strong need to avoid the generation of wasteful or harmful byproducts within the reactor network. This also a voids expensive treatment and separation costs downstream in the proce ss. In this study, we focus on the application of integrated reactor n etwork synthesis concepts for the vinyl chloride process. Vinyl chlori de is currently produced by a balanced process from ethylene, chlorine and oxygen with three separate reaction sections: oxychlorination of ethylene, direct chlorination of ethylene and pyrolysis of ethylene di chloride, with the hydrogen chloride produced in the pyrolysis reactor used completely in the oxychlorination reactor. Each of these reactio n sections generate chlorinated hydrocarbons and carbon oxides as bypr oducts. Detailed kinetic models for the three reaction sections are us ed to develop optimal reactor networks which improve the conversion of ethylene to vinyl chloride product and minimize the production of by- products. This case study presents an application of the mixed integer nonlinear programming based reactor network synthesis strategy (Laksh manan and Biegler, 1996a). A candidate flowsheet is proposed based on these results and a set of recommendations is given to improve the sel ectivity of vinyl chloride production.