Optimizing Control of CSTR/Distillation Column Processes with One Material Recycle

Abstract

Control system design for recycle processes that are composed of a continuous stirred tank reactor (CSTR) and a distillation column is discussed. It is shown that the reflux ratio control, which has been known to serve as a self-optimizing control for the process with the elementary chemistry A → B, can be also applied to processes with more-general types of chemistry that involves side reactions. Using the self-optimizing control as the basis, control systems that seek economically optimal operations are hierarchically constructed for example processes with different types of process chemistry. Particularly, for a process that exhibits tradeoff between product yield and separation cost, a linear model predictive controller design example is given with simulation results.