In the OG pressure control system equipped by only PI controller, there existed the problem that was very slow to respond to violent process fluctuations. The optimal control method was applied to improve this problem. Instead of installing another new sensing device, the existing sensing facilities were used and modification was made on the process variables which were measured by them. The higher controllability was achieved by means of the compensation of the delay time of the PI controller by identifing the process characteristics using higher differential equations.
In this paper, the new control system achieved by the method mentioned above is described. It is clearly indicated that the new method is very helpful in obtaining a high rate of LDG recovery.
