Design of a Multiloop One-Spot Tuning PID Controller and Its Application for a Crude Distillation Unit

In petroleum refineries and petrochemical processes, the production cost reduction is a key matter in improving competitiveness. Previously, the authors proposed the cyclic one-spot tuning PID control scheme for single-input and single-output systems, and applied it to the atmospheric distillation tower. The effectiveness of the proposed control scheme has been verified in steady operation mode. However, satisfactory performance could not be obtained when the operation mode was switched to transition operation mode. In order to overcome this problem, it is necessary to consider the influence of the interactions upon each input and each output. This paper presents a new multiloop one-spot tuning PID control scheme with a static pre-compensator. According to the newly proposed control scheme, satisfactory control performance can be obtained in both the steady and the transition operation modes.