Nonlinear Control of a Simulated Industrial Evaporation System Using a Feedback Linearization Technique with a State Observer

Abstract

This paper demonstrates the application of a feedback linearization control technique with a state observer on an industrial multiple-effect evaporation system of an alumina refinery. The nonlinear controller consists of a state feedback controller, single-input single-output (SISO) proportional−integral (PI) controllers, and a reduced-order observer. The simulation study serves to verify the performance of the nonlinear controller on the evaporation system by comparing the existing multiloop PI control system. Closed-loop simulation results showed that the nonlinear controller provides smoother operation for the evaporation despite significant model mismatches between the controller model and the simulated evaporator. A computer algorithm, consisting of the sequential execution code for the state feedback control law, SISO PI controllers, and a reduced-order observer, has been developed for implementation on the evaporator on-site.