Patent ID: 8425733
Filing Date: 2013-04-23
Classification: B01D,C02F,C07C,C10L

Abstract:
1. Method for dewatering a mixture of mostly ethanol and water comprising evaporation, distillation, compression, heat exchanging and vapour permeation or molecular sieve, characterized in that the feed flow ( 1 ) of mostly ethanol and water 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 ) while 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 under formation of 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 ) being condensed in a condenser ( 39 ) at an underpressure generated by a vacuum system illustrated by vacuum pump ( 43 ) 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 split in a water-rich bottom discharge flow ( 18 ) and an ethanol rich top discharge flow ( 7 ) while the retentate flow ( 11 ) is used as an energy source in a retentate heat exchanger ( 37 ) of the evaporator unit ( 31 ) before being discharged as a product flow ( 12 ).