Back to results
US 8,263,815 B2Granted
Membrane augmented distillation to separate solvents from water
AssigneesMembrane Technology and Research, Inc., United States Environmental Protection Agency
InventorsYu Huang, Richard W. Baker, Ramin Daniels, Tiem Aldajani, Jennifer H. Ly, Franklin R. Alvarez, Leland M. Vane
Life of this patent
Estimating the term…
Abstract
Processes for removing water from organic solvents, such as ethanol. The processes include distillation to form a rectified overhead vapor, compression of the rectified vapor, and treatment of the compressed vapor by two sequential membrane separation steps.
Claims32
A process for recovering an organic solvent from a solvent/water mixture, comprising:
- (a) subjecting the mixture to a distillation step comprising a stripping step performed in a stripping section and a rectification step performed in a rectification section, to produce a rectified vapor stream, enriched in organic solvent compared with the mixture, and a bottoms stream;
- (b) compressing at least a portion of the rectified vapor stream to form a compressed overhead vapor stream;
- (c) 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 compressed 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 first residue vapor stream enriched in solvent compared with the first compressed overhead vapor stream;
- (v) withdrawing from the first permeate side a first permeate stream enriched in water compared with the first compressed overhead vapor stream;
- (d) 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 vapor 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 a dehydrated solvent product;
- (v) withdrawing from the second permeate side a second permeate stream enriched in water compared with the first residue vapor stream;
- (e) recovering latent heat of condensation from the first permeate stream by returning the first permeate stream as a vapor to the stripping section.
12 more elements
A process for recovering an organic ethanol from an ethanol/water mixture, comprising:
- (a) subjecting the mixture to a distillation step comprising a stripping step performed in a stripping section and a rectification step performed in a rectification section, to produce a rectified vapor stream, enriched in organic solvent compared with the mixture, and a bottoms stream;
- (b) compressing at least a portion of the rectified vapor stream to form a compressed overhead vapor stream;
- (c) 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 ethanol;
- (ii) passing at least a portion of the compressed 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 first residue vapor stream enriched in ethanol compared with the first compressed overhead vapor stream;
- (v) withdrawing from the first permeate side a first permeate stream enriched in water compared with the first compressed overhead vapor stream;
- (d) 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 ethanol;
- (ii) passing at least a portion of the first residue vapor 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 a dehydrated ethanol product;
- (v) withdrawing from the second permeate side a second permeate stream enriched in water compared with the first residue vapor stream;
- (e) recovering latent heat of condensation from the first permeate stream by returning the first permeate stream as a vapor to the stripping section.
12 more elements
Dependencies are inferred from the claim text.