Abstract: An advanced process control (APC) project of multi-variable model predictive control was proposed to solve the problems of multi-disturbance, serious coupling and low automation in gas fractionator. During the execution of the project, it was difficult to obtain a reliable model for routine step test because of the long steady time caused by the large number of column plates and the long interval time of analyzer, and the product purity requirement was high, the step test would have great interference to the operation of the unit. In this paper, a dynamic model was built by Aspen Hysys dynamic software, and the step response curve of the dynamic model was used to build the predictive control model of APC project. The results show that the dynamic model has a good effect, greatly reduces the difficulty of step test, reduces the interference to the unit, and obtains a better control effect.

Key words: advanced process control, dynamic simulation, Hysys, C3 splitter, control optimization