LAUSR

The separation of toluene/pyridine by distillation still remains an obstacle in industry because of not only the formation of a minimum-boiling azeotrope but also their relative volatilities, whose ratio is close to unity throughout the whole composition range. Extractive distillation is still not feasible because it is hard to find suitable entrainers. Heterogeneous azeotropic distillation might require high energy consumption to obtain both purified products. Conventional pressure-swing distillation is also not feasible. In this work, we apply entrainer-assisted pressure-swing distillation to separate toluene/pyridine (95 mol %/5 mol %) by introducing n-propanol as an entrainer. Based on the different compositions of the recycling stream sent back to the azeotropic column, a two-column sequence and a three-column sequence are established. Both sequences are partially heat-integrated. The steady-state designs of both sequences are optimized based on the total annual cost (TAC). The results reveal that th...