CONTROL OF CHEMICAL REACTORS USING MULTIPLE-MODEL ADAPTIVE CONTROL (MMAC)

Abstract

Multiple-Model Adaptive Control (MMAC) is shown to be an effective strategy for controlling nonlinear chemical processes. In this paper, MMAC is applied to two difficult control problems that may be encountered in continuous stirred tank reactors (CSTRs). In the first example, product concentration is controlled in an isothermal CSTR exhibiting input multiplicities and non-minimum phase behavior (Van de Vusse reaction). The MMAC configuration provides disturbance rejection where a fixed-parameter PID controller fails. The second example involves temperature control of a CSTR which has output multiplicities. While a single PID controller can stabilize the plant over a large operating range, its performance can be quite poor since the plant dynamics vary widely. MMAC is shown to give significantly better performance when moving from the open-loop stable regions to the open-loop unstable operating region.