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US 8,114,255 B2Granted
Membrane-augmented distillation with compression to separate solvents from water
AssigneeMembrane Technology and Research, Inc.
InventorsLeland M Vane, Franklin R Alvarez, Yu Huang, Richard W Baker
Life of this patent
Estimating the term…
Abstract
Processes for removing water from organic solvents, such as ethanol. The processes include distillation in two columns operated at sequentially higher pressure, followed by treatment of the overhead vapor by one or two membrane separation steps.
Claims43
A process for recovering an organic solvent from a solvent and water mixture, comprising:
- (a) subjecting at least a portion of the mixture to a first distillation step, carried out by passing a first feed stream of the mixture, at a first pressure, into a first column having a reboiler system, to produce a solvent-enriched, first overhead vapor stream and a bottoms stream, wherein the bottoms stream consists essentially of water;
- (b) compressing at least a portion of the first overhead vapor stream to form a compressed overhead vapor stream;
- (c) subjecting the compressed overhead vapor stream to a second distillation step, carried out at a second pressure that is higher than the first pressure, in a second column having a reflux condenser system, to produce a solvent-enriched, second overhead vapor stream;
- (d) performing a first membrane separation step, comprising:
- (i) providing a first membrane having a first feed side and a first permeate side, the membrane being selective in favor of water over solvent;
- (ii) passing at least a portion of the second overhead vapor stream at a first feed pressure across the first feed side;
- (iii) maintaining a first permeate pressure on the first permeate side that is lower than the first feed pressure;
- (iv) withdrawing from the first feed side, as a first residue stream, a dehydrated solvent product;
- (v) withdrawing from the first permeate side a first permeate stream enriched in water compared with the second overhead vapor stream;
- (e) recovering heat by:
- (i) providing a heat exchanger that forms at least part of the reflux condenser system and at least part of the reboiler system;
- (ii) passing a reflux stream withdrawn from the second column through the heat exchanger;
- (iii) passing a reboil stream withdrawn from the first column through the heat exchanger in heat exchanging relationship with the reflux stream;
- and
- (f) recirculating the first permeate stream within the process to a distillation step selected from the group consisting of the first distillation step and the second distillation step.
12 more elements
A process for recovering an organic solvent from a solvent and water mixture, comprising:
- (a) subjecting at least a portion of the mixture to a first distillation step, carried out by passing a first feed stream of the mixture, at a first pressure, into a first column having a reboiler system, to produce a solvent-enriched, first overhead vapor stream and a bottoms stream, wherein the bottoms stream consists essentially of water;
- (b) compressing at least a portion of the first overhead vapor stream to form a compressed overhead vapor stream;
- (c) subjecting the compressed overhead vapor stream to a second distillation step, carried out at a second pressure that is higher than the first pressure, in a second column having a reflux condenser system, to produce a solvent-enriched, second overhead vapor stream;
- (d) performing a first membrane separation step, comprising:
- (i) providing a first membrane having a first feed side and a first permeate side, the membrane being selective in favor of water over solvent;
- (ii) passing at least a portion of the second overhead vapor stream at a first feed pressure across the first feed side;
- (iii) maintaining a first permeate pressure on the first permeate side that is lower than the first feed pressure;
- (iv) withdrawing from the first feed side a partially dehydrated first residue stream;
- (v) withdrawing from the first permeate side a first permeate stream enriched in water compared with the second overhead vapor stream;
- (e) performing a second membrane separation step, comprising:
- (i) providing a second membrane having a second feed side and a second permeate side, the membrane being selective in favor of water over solvent;
- (ii) passing at least a portion of the first residue stream at a second feed pressure across the second feed side;
- (iii) maintaining a second permeate pressure on the second permeate side that is lower than the second feed pressure;
- (iv) withdrawing from the second feed side, as a second residue stream, a further dehydrated solvent product;
- (v) withdrawing from the second permeate side a second permeate stream enriched in water compared with the first residue stream;
- (f) performing a step selected from the group consisting of steps (g) and (h) as follows:
- (g) recovering heat by:
- (i) providing a heat exchanger that forms at least part of the reflux condenser system and at least part of the reboiler system;
- (ii) passing a reflux stream withdrawn from the second column through the heat exchanger;
- (iii) passing a reboil stream withdrawn from the first column through the heat exchanger in heat exchanging relationship with the reflux stream;
- (h) recirculating at least one of the permeate streams within the process to a distillation step selected from the group consisting of the first distillation step and the second distillation step.
18 more elements
A process for producing a light alcohol, comprising the following steps:
- (a) fermenting a sugar to form a fermentation broth comprising the alcohol and water;
- (b) subjecting at least a portion of the fermentation broth to a first distillation step, carried out by passing a first feed stream of the fermentation broth, at a first pressure, into a first column having a reboiler system, to produce an alcohol-enriched, first overhead vapor stream and a bottoms stream, wherein the bottoms stream consists essentially of water;
- (c) compressing at least a portion of the first overhead vapor stream to form a compressed overhead vapor stream;
- (d) subjecting the compressed overhead vapor stream to a second distillation step, carried out at a second pressure that is higher than the first pressure, in a second column having a reflux condenser system, to produce an alcohol-enriched, second overhead vapor stream;
- (e) performing a first membrane separation step, comprising:
- (i) providing a first membrane having a first feed side and a first permeate side, the membrane being selective in favor of water over alcohol;
- (ii) passing at least a portion of the second overhead vapor stream at a first feed pressure across the first feed side;
- (iii) maintaining a first permeate pressure on the first permeate side that is lower than the first feed pressure;
- (iv) withdrawing from the first feed side, as a first residue stream, a dehydrated alcohol product;
- (v) withdrawing from the first permeate side a first permeate stream enriched in water compared with the second overhead vapor stream;
- (f) recovering heat by:
- (i) providing a heat exchanger that forms at least part of the reflux condenser system and at least part of the reboiler system;
- (ii) passing a reflux stream withdrawn from the second column through the heat exchanger;
- (iii) passing a reboil stream withdrawn from the first column through the heat exchanger in heat exchanging relationship with the reflux stream;
- and
- (g) recirculating the first permeate stream within the process to a destination selected from the group consisting of the fermentation step (a), the first distillation step (b) and the second distillation step (d).
13 more elements
Dependencies are inferred from the claim text.