Appropriate selections of distillation column control variable to improve integrating material recycle response

Abstract

The distillation column control strategy in a standalone column ensures a safe and stable column operation by holding the purities/or impurities in distillate and bottoms product streams. In general, the sensitivity analysis method provides the column control variable which contributes in robust process operation, however, in this example the importance of control variables selection through different methods are compared for a specific case study where the distillation column is located/placed inside the recycle loops of two different recycle streams. The control variables for distillation column located within two different recycle loops is first selected using sensitivity analysis shows an integrating (ramp like) recycle flow rate for a nominal (±10%) throughput change. Later, a thorough dynamic analysis is implemented with control variables obtained from different methods to understand this peculiar recycle response. Further, these methods are discussed to improvise the dynamic response. Keywords: Azeotropic distillation, Control variable, Material imbalances, Recycle response