Dynamics and control of heat integrated distillation column (HIDiC)

A heat integrated distillation column (HIDiC) is a new and highly energy-efficient distillation process. In the present work, dynamic simulation models for several types of HIDiCs were developed. The energy efficiency, dynamics, and controllability of HIDiCs were investigated by using the developed simulator, and these characteristics were compared with those of a conventional distillation column (CDiC). HIDiC has a more complex structure and slower dynamics than CDiC, but the control performance of HIDiC is comparable to that of CDiC as long as a suitable control system is designed. The distillate flow rate (D) is superior to the reflux flow rate (L) as a manipulated variable, because the dynamics of HIDiC becomes considerably faster by using D rather than L. To achieve high energy efficiency and controllability at the same time, it is recommended to adopt the structure in which the feed is preheated by distillate vapor (product), a condenser is used, and a reboiler is not used. In addition, the control performance of HIDiC becomes better as the heat transfer area decreases, and it becomes slightly better as the pressure difference between the stripping section and the rectifying section decreases.