Profile Position Control of Extractive Thermally Coupled Distillation System

Extractive distillation system can be used when the components to be separated have close boiling points or form azeotropes. Extractive distillation is one of the most important and widely used separation methods in chemical process industry. The main disadvantage of the distillation is its high-energy requirements. Thermally coupled distilla- tion system (TCDS) can provide significant savings in energy consumption and capital cost over the operation of sequences based on conventional distillation column. Despite such advantages of the thermally coupled distillation sys- tem, the process is not widely used in industry because control and operation of the column are difficult. In this study, we propose several control schemes for thermally coupled distillation system to overcome the difficulties and make the column stable when the process is confronted with feed disturbances. Profile position control scheme shows best control performance among the proposed control schemes.