A new energy-integrated pervaporation distillation approach

Abstract

Hybrid-pervaporation-distillation processes have been intensely studied in the last years and considered as a good alternative in the separation of homogeneous azeotropic mixtures. Compared with the techniques in use in the chemical industry, they can reduce the energy consumption and avoid the use of entrainers. However, due to the evaporation enthalpy, a temperature drop is presented along the membrane and external heat exchangers are required between two consecutive pervaporation steps. In the present paper, a process approach has been developed in order to avoid the external energy support and the temperature drop along the module. The novel energy integration concept utilizes the distillate vapor stream of a distillation column as heating medium in the membrane. The vapor condenses partially and energy is released directly into the module. For the study of the new energy integrated process, a novel membrane configuration is developed and a mathematical model is built. Simulation results show that the new process can yield to higher permeation fluxes and smaller temperature drop in the membrane, what also means a reduction in the required membrane area, if a constant purity in the product is considered. Due to the energy integration concept, there is no need of external heat supply in the pervaporation and the permeate flux rises, which can reduce the operation and investment costs.