アルコール濃縮膜プロセスの最適化

Abstract

A distillation process has been used for alcohol concentration, and this process is a typical energy-consuming process. Recently the green house effect becomes big problem in the world, and thus an energy-saving process is very much required. Membrane processes are well-known energy-saving processes and applicable to the ethanol concentration.For concentrating ethanol solution there are two possible membrane processes : reverse osmosis (RO) and pervaporation (PV) processes. Furthermore in each process both water selective and ethanol selective membranes are available.In the PV process a vacuum pump consumes much energy and latent heat supply is also necessary. On the other hand, in the RO process, operating pressure must be greatly high because of high osmotic pressure of ethanol and water, and much energy is needed. Therefore selecting the appropriate membrane and the process is very important.In this study, several hybrid membrane processes, for instance ethanol-selective/water-selective PV, ethanol-selective PV/water-selsctive RO, ethanol-selective/water-selsctive RO and so on, for the concentration of ethanol solution from 10wt% to 96wt% with ethanol recovery more than 95% were designed by computer simulation based on the solution-diffusion mechanism. Then the processes were optimized in order to reduce membrane area and energy consumption.It was found that PV process is not a energy-saving process comparing with distillation process, but RO process consumes extremely small amount of energy even with super high applied pressure, such as 30MPa.