Dynamic simulation and control of an integrated gasifier/reformer system. Part II: Discrete and model predictive control

Part I of this series presented an analysis of a multi-loop proportional-integral (PI) control system for an integrated coal gasifier/steam methane reformer system, operating in both counter-current and co-current configurations, for syngas production in a flexible polygeneration plant. In this work, a discrete-PI control system and an offset-free linear model predictive controller (MPC) are presented for the co-current configuration to address process interactions and sampling delay. The MPC model was identified from ‘data’ derived from simulations of the rigorous plant model, with a Luenberger observer augmented to the MPC, to estimate and eliminate plant-model mismatch. MPC offered superior set point tracking relative to discrete-PI control, especially in cases where discrete-PI destabilized the system. The offset-free MPC was developed to solve in less than a second to facilitate online deployment.