Design strategy for heat pump assisted distillation system

Distillation columns are the major energy-consuming units in the chemical and petrochemical industries. The heat integration concept [1] attempts to integrate the heating and cooling demands of a column within the heat network of the overall process. In case of stand-alone unit or severe restrictions on integrability of distillation column, the realization of heat pump assisted distillation seems to be one of the most promising energy saving techniques. Because of its less energy demand, the heat pump assisted distillation reduces the operating cost and occasionally can compensate the additional capital expenses of compressor. Based on the COP and energy costs, simple expressions are developed for preliminary economic analysis and design of heat pump assisted distillation. A design strategy is proposed for selecting the most economical distillation system based on the energy cost factor and the estimated payback time of excess capital. The strategy is demonstrated by two examples.