A Hybrid Method for Integration of Heat Pump Assisted Distillation System with Intermediate Reboiler/condenser

Setting an intermediate reboiler/condenser for heat transfer with the heat pump can reduce both requirements of hot and cold utilities and the temperature lift of the heat pump. This paper proposes a hybrid method that combines rigorous process simulation and mathematical programming for targeting the optimal heat pump placement in the presence of intermediate reboiler/condenser to minimize the overall energy consumption. First, the grand composite curve of distillation column is determined via rigorous process simulation. A simulation model for the vapor compression heat pump is also established. Next, the column grand composite curve is taken as constrains for formulating a simulation-based optimization model by data interaction between Aspen HYSYS and Matlab. The model is solved using the genetic algorithm toolbox to determine the optimal placement of the heat pump. A de-heavy fractionator in the isobutene unit is studied to illustrate the applicability of the proposed method.