Advanced process control of an acetaldehyde distillation units

The acetaldehyde distillation units are composed of two distillation columns; one is used to remove the light component and one end-product column. Coupling problems in the end-product column are encountered because of the dual component control strategy implemented by conventional PID control, due to heat integration, coupling problems are also existed between the two columns, which cause the operation of the distillation units difficult. In this paper, an advanced process control and optimization application is introduced. The control tasks of the two columns are considered together by a multi-variable model predictive controller to overcome the mentioned problems. Compared to original PID control, the improvements of control performance can be observed by the reduced variant range of the columns temperature. An economic optimization between steam consumption and product quality is also implemented, which ensure that the operating points of distillation units move towards its optimal steady-operating points.