Patent ID: 8585904

Claim:
A dehydration method comprising the steps of: providing a distilled process-target fluid to a water separation membrane device via a heat exchanger, the process-target-fluid consisting of a mixture comprising ethanol and water or a mixture of propanol and water; separating the process-target fluid into a dehydrated product and water by using the water separation device; detecting a temperature of the water separation membrane device and the process-target fluid to the water separation membrane device by using a temperature monitoring device; and controlling the temperature of the process-target fluid so that the temperature of the distilled process-target fluid is maintained at a temperature higher than the condensation temperature of the distillate by 5 to 10° C. by using a temperature adjustment device provided in the water separation membrane device, the temperature adjustment device being a heat medium flow rate controller which control the amount of the heat medium into the heat exchanger on the bases of the temperature detected by the temperature monitoring device to optimize an amount of water permeation in a separation process in the water separation membrane device; wherein the process target-fluid is obtained by dehydrating a raw material through an alcohol selective permeation membrane.