Continuous reactor network design for multiple rigid polyol productions

Abstract

This study focuses on developing continuous reactor network models able to produce multiple rigid polyol products under strict product and safety specifications. We first determine reactor networks and operating decisions for minimum capital cost, and then find reactor networks with optimal profit through multi-criteria optimization, using a Pareto chart to analyze the relationship between capital cost and net sales. Based on our previous study, we narrow down the types of continuous reactors that can be part of the network to two: plug flow reactor (PFR) with multiple feed injection points and a network of continuous stirred tank reactors (CSTR). The CSTR model can be written as a mixed integer nonlinear programming (MINLP) problem. The PFR model is a differential algebraic equation (DAE) optimization problem. The simultaneous collocation method is applied to transform the resulting DAE model into an MINLP, which is solved as a NLP by fixing the binary terms. Both capital cost and multi-criteria problems are formulated as multi-scenario optimization problems to determine the best single network design to produce multiple polymer products.