A thermally coupled azeotropic dividing wall column (ADWC) configuration is explored for the separation of industrial wastewater to recycle the organic solvent tert-butanol. Heat pump technology is used to the ADWC configuration to improve the released heat duty quality of the condenser achieving the energy-saving. A gas preheater before the compressor is installed in the heat pump assisted ADWC configuration in increasing the temperature of the inlet vapour stream of the compressor that achieves effectively reducing the power and compression ratio of the compressor. To fully utilize a large amount of superheat energy produced in heat pump system indicated by the temperature-enthalpy and Grand Composite Curve diagrams, a green and sustainable Heat Integrated ADWC (HI-ADWC) separation configuration is proposed by the combined use of heat exchange network and heat pump implementations. Three indexes involving total annual cost, CO2 emissions, and exergy loss are introduced to evaluate the economic, environmental and thermodynamic performances. The results illustrate that the TAC of the proposed green and sustainable HI-ADWC configuration is significantly reduced by 32.91% with a ten-year payback period compared to that of the existing configuration. CO2 emissions are reduced by 86.43% and exergy loss of the HI-ADWC configuration by 36.72%. The proposed method for the green and sustainable HI-ADWC configuration could be widely extended to other industrial processes reduce energy consumption and related CO2 emissions.

Introduction

Distillation technology has been developed for separating and purifying of mixtures in the chemical industrial due to its advantages in the operation (Sharan et al., 2018) and control (Luyben and Chien, 2011). However, a drawback of the conventional distillation is required a great deal of energy consumption to achieve the separation task (Kiss and Ignat, 2012). In addition, a large amount of CO2 emissions contribute to global warming (Wang et al., 2019b). Intensified distillation processes need to develop to overcome the above issues achieving the performance of energy-saving, cleaner production and environmental protection (Matsuda et al., 2012). To achieve the energy-saving, distillation processes with Heat Integration by changing operating pressure as technology is explored. For example, a novel pressure-swing extractive distillation configuration for separating acetone/methanol binary minimumboiling azeotropic mixture is explored (You et al., 2017). The application of Heat Integration (Kleme
s, 2013) for the extractive distillation process to separate tetrahydrofuran/water mixtures with lower operational pressure is then investigated (Gu et al., 2018). Design and optimization of ternary extractive distillation for separating acetonitrile/methanol/water was proposed by Wang et al. (2019a), and the calculation illustrates that total annual cost (TAC) of the lower operating pressure scheme can reduce by 47.0% than the operating at atmosphere pressure. Following that, the vacuum distillation scheme for low-sulfur biodiesel production was explored by Xie et al. (2019). A novel separation configuration as another energy-saving technology has been investigated. A novel energysaving extractive distillation with side-stream was studied by Tututi-Avila et al. (2017) for the separation of acetone/methanol mixtures using water as entrainer.