The invention discloses a four-
tower distillation and membrane separation integrated
system, which comprises a mash liquid pre-heater, a negative pressure mash
tower, a normal pressure mash
tower, a
medium pressure rectification tower and a
high pressure rectification tower, wherein the
high pressure rectification tower is sequentially connected to an
alcohol gas overheating device and a membraneseparation device through pipelines, the membrane separation device comprises a
low vacuum membrane
assembly and a high vacuum membrane
assembly, and the
low vacuum membrane
assembly and the high vacuum membrane assembly are connected in series. The method for distilling
ethanol by using the
system comprises that A, gas is removed from fermented mature mash to form degassed mash; B, the
alcohol vapor is separated from the waste mash liquid in the degassed mash; C, the
alcohol vapor is condensed to form a crude alcohol, the crude alcohol is distilled by the
medium pressure rectification tower,and the obtained material enters the
high pressure rectification tower; and D, the alcohol vapor entering the high pressure rectification tower is partially overheated, and the obtained material sequentially enters the
low vacuum membrane assembly and the high vacuum membrane assembly to separate the
ethanol and the water. According to the present invention, with the
system and the method, the phenomenon of alcohol volatilization in the
distillation process can be avoided, the consumption of freezing water and steam can be reduced, and the system and the method are energy-saving and
environmentally friendly.