Patent ID: 8608966

Claim:
A method for dewatering a mixture of ethanol and water, comprising: feeding a mixture of ethanol and water into an evaporator, evaporating said mixture in the evaporator and feeding a stream of vaporized mixture of ethanol and water from the evaporator to a vapor recompression unit, pressurizing said vaporized mixture of ethanol and water in the vapor recompression unit and feeding a stream of pressurized vaporized mixture of ethanol and water from the vapor recompression unit to a membrane unit, dividing said stream of pressurized mixture of ethanol and water in the membrane unit in a vapor permeation step into (i) a vaporized permeate stream of vaporized mixture of residual ethanol and water and feeding the vaporized permeate stream of vaporized mixture of residual ethanol and water from the membrane unit and, (ii) into a retentate stream of dewatered mixture of ethanol and residual water from the membrane unit, using a dewatering unit comprising a cooling unit and a distillation column, feeding the vaporized permeate stream of vaporized mixture of residual ethanol and water from the membrane unit into the cooling unit of the dewatering unit and condensing the vaporized permeate stream of vaporized mixture of residual ethanol and water in the cooling unit to a liquid permeate stream of residual ethanol and water and feeding the liquid permeate stream of residual ethanol and water into the distillation column, dividing the liquid permeate stream of residual ethanol and water in the distillation column in a distillation step into (i) a second stream of dewatered mixture of ethanol and residual water, and into (ii) a stream of water, discharging the stream of water from the distillation column, and feeding the second stream of dewatered mixture of ethanol and residual water from the distillation column directly to the evaporator.