Self-Optimizing Control in Chemical Recycle Processes

Abstract

An engineer always has to make assumptions about the system boundary. In this paper, the impact of neglected dependencies of manipulated variables on the disturbance variables as example for said assumptions is investigated in the context of self-optimizing control. The feedback through dependent disturbances influences both the optimal operating point and the combination of measurements. As a case study, we consider an ammonia synthesis reactor with a simplified model for the ammonia separation and the recycle. The disturbance dependency changes the optimal selection matrices through the recycle. However, we find that it is possible to neglect the recycle in the selection of the controlled variables for this example if the setpoint is adjusted.