Economic Optimization and Hazard Analysis of a Mono-Chlorobenzene Process

The process of chlorinating benzene to produce mono-chlorobenzene was modeled using five series/parallel reactions to include the dichloro and trichlorobenzene byproducts.  A target of 10,000 lb/hr of 99.5% pure mono-chlorobenzene was specified.  Up to 1000 lb/hr of dichlorobenzene (ortho or para) could be sold.  Hydrochloric acid maybe sold as a byproduct at a concentration of 35 wt% depending upon impurities.  All trichlorobenzene had to be disposed of as hazardous waste.  The system was modeled using the process simulator ChemCAD and priced using cost equations from Turton, Bailie, Whiting and Shaeiwitz (2012).  Both topological and parametric optimizations were considered.  The recycle streams increased the complexity of the simulator significantly, but were required to accurately model the concentration build-up in the system.  The impact of reactor residence time, separator recycle purity, and feed ratio on the economics will be presented.  Process hazards will be identified and suggestions to mitigate hazards will be presented.