Multiloop Control Strategies for a Dry Feeding Gasifier in the Integrated Gasification Combined Cycle

Abstract

Three control strategies for a dry feeding gasifier are studied. First examined is the fixed-ratio control strategy which keeps fixed ratios of the different feeds. Simulation results show that this strategy moves the system along a suboptimal path during load changes as the fixed ratios are selected for a steady-state operation. Two of the three chosen controlled variables (CVs) did not settle back to their set-points in the disturbance rejection test. To improve the performance, a new control strategy is proposed which adds additional loops to adjust the feed ratios in a cascade manner. Under this strategy, the set-points are well tracked and disturbances are rejected properly. The third strategy examines the necessity of the ratio controllers by breaking the ratio loops. While the strategy works reasonably, the chosen manipulated variable (MV)-CV pairings are counterintuitive. In the load change test, one of MVs is reduced to the lower limit and CVs fluctuate significantly.