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US 8,128,787 B2Granted
Membrane-augmented distillation with pressure change to separate solvents from water
AssigneeNitto Denko Corporation
InventorsNicholas P. Wynn, Yu Huang, Masakatsu Urairi, Richard W Baker
Life of this patent
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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.
Claims62
A process for recovering an organic solvent from a solvent and water mixture, comprising:
- (a) subjecting at least a first 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 first reboiler system, to produce a solvent-enriched, first overhead vapor stream and a first bottoms stream, wherein the first bottoms stream consists essentially of water;
- (b) condensing the first overhead vapor stream to form a condensed overhead stream;
- (c) pumping at least a portion of the condensed overhead stream to a second distillation step, carried out under a second pressure that is higher than the first pressure in a second column having a second reboiler system and a reflux condenser system, to produce a solvent-enriched, second overhead vapor stream and a second bottoms stream;
- (d) performing a membrane separation step, comprising:
- (i) providing a membrane having a feed side and a 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 feed pressure across the feed side;
- (iii) maintaining a permeate pressure on the permeate side that is lower than the feed pressure;
- (iv) withdrawing from the feed side, as a residue stream, a dehydrated product stream;
- (v) withdrawing from the permeate side a 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 first reboiler system;
- (ii) passing through the heat exchanger as a heating stream at least one stream selected from the group consisting of (I) the dehydrated product stream, (II) a reflux stream withdrawn from the second column, and (III) the second bottoms stream;
- (iii) passing a reboil stream withdrawn from the first column through the heat exchanger in heat exchanging relationship with the heating stream;
- and
- (f) recirculating the permeate stream within the process.
12 more elements
A process for recovering an organic solvent from a solvent and water mixture, comprising:
- (a) subjecting at least a first 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 first reboiler system, to produce a solvent-enriched, first overhead vapor stream and a first bottoms stream, wherein the first bottoms stream consists essentially of water;
- (b) condensing the first overhead vapor stream to form a condensed overhead stream;
- (c) pumping at least a portion of the condensed overhead stream to a second distillation step, carried out under a second pressure that is higher than the first pressure in a second column having a second reboiler system and a reflux condenser system, to produce a solvent-enriched, second overhead vapor stream and a second bottoms 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 a first residue stream from the first feed side;
- (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 dehydrated solvent product;
- (v) withdrawing from the second permeate side a second permeate stream enriched in water compared with the first residue stream;
- (f) recovering heat by:
- (i) providing a heat exchanger that forms at least part of the first reboiler system;
- (ii) passing through the heat exchanger as a heating stream at least one stream selected from the group consisting of (I) the dehydrated product stream, (II) a reflux stream withdrawn from the second column, and (III) the second bottoms stream;
- (iii) passing a reboil stream withdrawn from the first column through the heat exchanger in heat exchanging relationship with the heating stream;
- and
- (g) recirculating the second permeate stream within the process.
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 the fermentation broth to a first distillation step, carried out by passing a first feed stream of at least a first portion of the fermentation broth, at a first pressure, into a first column having a first reboiler system, to produce an alcohol-enriched, first overhead vapor stream and a first bottoms stream, wherein the first bottoms stream consists essentially of water;
- (c) condensing the first overhead vapor stream to form a condensed overhead stream;
- (d) pumping at least a portion of the condensed overhead stream to a second distillation step, carried out under a second pressure that is higher than the first pressure in a second column having a second reboiler system and a reflux condenser system, to produce an alcohol-enriched, second overhead vapor stream and a second bottoms stream;
- (e) performing a membrane separation step, comprising:
- (i) providing a membrane having a feed side and a 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 feed pressure across the feed side;
- (iii) maintaining a permeate pressure on the permeate side that is lower than the feed pressure;
- (iv) withdrawing from the feed side, as a residue stream, a dehydrated alcohol product;
- (v) withdrawing from the permeate side a 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 first reboiler system;
- (ii) passing through the heat exchanger as a heating stream at least one stream selected from the group consisting of (I) the dehydrated product stream, (II) a reflux stream withdrawn from the second column, and (III) the second bottoms stream;
- (iii) passing a reboil stream withdrawn from the first column through the heat exchanger in heat exchanging relationship with the heating stream;
- and
- (g) recirculating the permeate stream within the process.
13 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 first 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 first reboiler system, to produce an alcohol-enriched, first overhead vapor stream and a first bottoms stream, wherein the first bottoms stream consists essentially of water;
- (c) condensing the first overhead vapor stream to form a condensed overhead stream;
- (d) pumping at least a portion of the condensed overhead stream to a second distillation step, carried out under a second pressure that is higher than the first pressure in a second column having a second reboiler system and a reflux condenser system, to produce an alcohol-enriched, second overhead vapor stream and a second bottoms 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 a first residue stream from the first feed side;
- (v) withdrawing from the first permeate side a first permeate stream enriched in water compared with the second overhead vapor stream;
- (f) 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 alcohol;
- (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 dehydrated alcohol product;
- (v) withdrawing from the second permeate side a second permeate stream enriched in water compared with the first residue stream;
- (g) recovering heat by:
- (i) providing a heat exchanger that forms at least part of the first reboiler system;
- (ii) passing through the heat exchanger as a heating stream at least one stream selected from the group consisting of (I) the dehydrated product stream, (II) a reflux stream withdrawn from the second column, and (III) the second bottoms stream;
- (iii) passing a reboil stream withdrawn from the first column through the heat exchanger in heat exchanging relationship with the heating stream;
- and
- (h) recirculating the second permeate stream within the process.
19 more elements
A process for recovering an organic solvent from a solvent and water mixture, comprising:
- (a) subjecting a first portion of the mixture to a first distillation step at a first pressure, carried out by passing a first feed stream of the mixture into a first column having a first reboiler system, to produce a solvent-enriched, first overhead vapor stream and a first bottoms stream, wherein the first bottoms stream consists essentially of water;
- (b) condensing the first overhead vapor stream to form a condensed overhead stream;
- (c) passing a second portion of the mixture and pumping at least a portion of the condensed overhead stream to a second distillation step carried out under a second pressure that is higher than the first pressure in a second column having a second reboiler system and a reflux condenser system, to produce a solvent-enriched, second overhead vapor stream and a second bottoms stream;
- (d) performing a membrane separation step, comprising:
- (i) providing a membrane having a feed side and a 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 feed pressure across the feed side;
- (iii) maintaining a permeate pressure on the permeate side that is lower than the feed pressure;
- (iv) withdrawing from the feed side, as a residue stream, a dehydrated product stream;
- (v) withdrawing from the permeate side a 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 first reboiler system;
- (ii) passing through the heat exchanger as a heating stream at least one stream selected from the group consisting of (I) the dehydrated product stream, (II) a reflux stream withdrawn from the second column, and (III) the second bottoms stream;
- (iii) passing a reboil stream withdrawn from the first column through the heat exchanger in heat exchanging relationship with the heating stream;
- and
- (f) recirculating the first permeate stream within the process.
12 more elements
A process for recovering an organic solvent from a solvent and water mixture, comprising:
- (a) subjecting at least a first 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 first reboiler system, to produce a solvent-enriched, first overhead vapor stream and a first bottoms stream, wherein the first bottoms stream consists essentially of water;
- (b) condensing the first overhead vapor stream to form a condensed overhead stream;
- (c) passing a second portion of the mixture and pumping at least a portion of the condensed overhead stream to a second distillation step, carried out under a second pressure that is higher than the first pressure in a second column having a second reboiler system and a reflux condenser system, to produce a solvent-enriched, second overhead vapor stream and a second bottoms 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 a first residue stream from the first feed side;
- (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 dehydrated solvent product;
- (v) withdrawing from the second permeate side a second permeate stream enriched in water compared with the first residue stream;
- (f) recovering heat by:
- providing a heat exchanger that forms at least part of the first reboiler system;
- (ii) passing through the heat exchanger as a heating stream at least one stream selected from the group consisting of (I) the dehydrated product stream, (II) a reflux stream withdrawn from the second column, and (III) the second bottoms stream;
- (iii) passing a reboil stream withdrawn from the first column through the heat exchanger in heat exchanging relationship with the heating stream;
- and
- (g) recirculating the second permeate stream within the process.
18 more elements
Dependencies are inferred from the claim text.