DYNAMIC ANALYSIS OF DISTILLATION WITH THERMAL COUPLING FOR DIFFERENT OPERATING CONDITIONS

Thermally coupled distillation sequences (TCDS) exhibit a more complex structure, with recycle streams, that appear to affect their controllability properties. One poten-tial solution to this problem is considering the operation of TCDS under conditions that do not provide minimum energy consumption. The basic idea is that if one changes the operation point, the control properties might change as well. In this work, we analyze the dynamic performance of two TCDS structures (in particular, systems with side columns) under different operating points, including the one with minimum energy consumption. The control analysis properties are analyzed with the application of the singular value decomposition technique and closed-loop dynamic responses using standard PI controllers. The results show that the controll-ability properties of distillation sequences may change significantly depending on the selected operation point. In particular, we show that the dynamic properties of TCDS can be improved by switching from a design with minimum energy consumption to another one in which a higher level of energy consumption is allowed (but an energy consumption lower than the conventional schemes)