Improving the Performance of Heat Pump-Assisted Azeotropic Dividing Wall Distillation

Abstract

In this work, three vapor recompression heat pump (VRHP) models are designed for the azeotropic dividing-wall column (A-DWC) system to study the energy-saving effect. During the determination of these three models, how the top stream pipeline designs affect the energy consumption is discussed. As adding a preheater can cut down compressor pressure ratio and splitting top stream can decrease the feed flow of the compressor, all these methods can obviously help reduce compressor work for the process. Evaluation results show that the VRHP A-DWC systems have a better performance in energy consumption and environmental sustainability. Especially for Model 3, the savings of total operating cost (TOC) is 47.77% and that of the total annual cost (TAC) is 32.22%, compared with the conventional two-column azeotropic system. CO2 emissions in the process of model 3 can be reduced by 63.79%, and the thermodynamic efficiency increased to 22.64%.