Fremgangsmåde til afvanding af en blanding, som hovedsageligt består af ethanol og vand.

摘要

Method for dewatering a mixture of mostly ethanol and water which is split into a first partial feed flow (3) that is directed to a distillation column (32) as a reflux flow while a second partial feed flow (4) is directed to an evaporator unit (31) as an evaporator inlet flow and leaves the top of the evaporator unit as an evaporator outlet flow (6). A top discharge flow (7) from distillation column (32) is returned and combined with the evaporator outlet flow (6) to a combined flow (8) at an overpressure and which in a compressor unit (33) is compressed to a combined, compressed flow (10) which enters a dewatering unit (34) in which it is split into a water-rich permeate flow (14) and a retentate flow (11) in the form of substantially water free ethanol. The permeate flow (14) is condensed in a condenser (39) at an underpressure whereafter permeate flow (15) is pressurized by a pump (42) to a flow (16) which is fed to distillation column (32), which is supplied with external thermal energy by a heat exchanger (36), and there split into a water rich bottom discharge flow (18) and an ethanol-rich top discharge flow (7). The retentate flow (11) is used an energy source in a retentate heat exchanger (37) of evaporator unit (31) before leaving as a product flow (12).