Novel energy-efficient designs of heterogeneous azeotropic distillation for separating ternary organic wastewater based on self-heat recuperation technology

The presence of a heterogeneous region in the ternary diagram of 1,4-dioxane/water/ethyl acetate allows for separation by conventional three-column heterogeneous azeotropic distillation (HAD). Considering the characteristics of the ternary phase diagram, two novel heterogeneous azeotropic processes are designed, which are the heterogeneous azeotropic distillation process by adding pure ETAC as the self-solvent (HAD-PE) and heterogeneous azeotropic distillation process with partial organic phase reflux (HAD-OPR). Subsequently, self-heat recuperation (SHR) technology is introduced to the HAD-PE and HAD-OPR processes to achieve energy savings. Finally, the economic, energy, environmental and exergy aspects of the process are evaluated. Both configurations of HAD-PE and HAD-OPR are superior to HAD. The results show that the HAD-OPR-SHR process is the optimal process, with a total annual cost (TAC) reduction of 64.28%, TEC reduction of 74.62%, gas emission reduction of 72.84%, and exergy loss reduction of 74.43% compared with the HAD process.