On the Application of Single Loop, Decoupling and Davison's Robust Control to a Heat Exchanger-Stirred Tank Process

Abstract

<p>Three different control strategies are compared in the control of the output temperature and the total flowrate of a heat exchanger stirred tank process: single loop control, Davison's robust control and decoupling control.</p> <p>When the single loop control was applied, interactions between the process variables were observed when the flow setpoint was changed. This resulted in large oscillations in the temperature. The load responses were, however, satisfactory. It was shown that Davison's robust controller was similar to a static decoupler using two integral feedback controllers of the same gain. The integral mode alone was not found to be adequate for the control of the slow temperature process. Static decoupling gave satisfactory results for both setpoint and load changes. There was some improvement, although-not very great, when dynamic decoupling was applied. This was because the cross and direct dynamics of the temperature processes had approximate time constants.</p>