A case study for reactor network synthesis: The vinyl chloride process

Abstract

A key objective of the integrated reactor network synthesis approach is the development of waste minimizing process flowsheets ( Lakshmanan and Biegler, 1994). With increasing environmental concerns in process design, there is a particularly strong need to avoid the generation of wasteful or harmful byproducts within the reactor network. This also avoids expensive treatment and separation costs downstream in the process. In this study, we focus on the application of integrated reactor network synthesis concepts for the vinyl chloride process. Vinyl chloride 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 dichloride, with the hydrogen chloride produced in the pyrolysis reactor used completely in the oxychlorination reactor. Each of these reaction sections generate chlorinated hydrocarbons and carbon oxides as byproducts. Detailed kinetic models for the three reaction sections are used 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 ( Lakshmanan and Biegler, 1996a). A candidate flowsheet is proposed based on these results and a set of recommendations is given to improve the selectivity of vinyl chloride production.