US4473473A
Expired / Lapsed
US
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Method and apparatus for distillation
Assignee: International Microporous Technology Inc
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Filing: 1981-02-02
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Granted: 1984-09-25
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Expires: 2001-02-02
Abstract
Abstract A composite membrane structure is used in a distillation apparatus and method. The composite membrane separates a distilland and a distillate, such as salt water and fresh water. The composite membrane comprises a thin lyophobic microporous layer of membrane and a thin lyophilic layer of membrane. Evaporation and condensation takes place within the micropores of the lyophobic membrane. The lyophilic layer prevents intrusion of distilland into the pores of the lyophobic layer.
Inventors
- 👤 Dah Yu Cheng
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:06
CPC Classifications
B; B01; B01D; B01D69/00; B01D69/12; B01D69/1213; B01D69/1218; B32; B32B; B32B27/00; B32B27/06; B32B27/08
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
90 words
A composite membrane for applications where unidirectional passage of water vapor is required comprising a layer of porous, nonwettable, hydrophobic polyvinylidene fluoride through which water is prevented from passing in the form of a liquid but passes in the form of a vapor and barrier means for preventing any liquids, including salt-bearing liquids, from intruding within the pores of said polyvinylidene fluoride layer while allowing passage of water vapor through the pores of said polyvinylidene fluoride layer, comprising a hydrophilic layer substantially on the surface of the polyvinylidene fluoride layer.
Claim 2
Dependent Claim
90 words
A composite membrane for applications where unidirectional passage of water vapor is required comprising a layer of porous, nonwettable, hydrophobic polyvinylidene fluoride through which water is prevented from passing in the form of a liquid but passes in the form of a vapor and barrier means for preventing any liquids, including salt-bearing liquids, from intruding within the pores of said polyvinylidene fluoride layer while allowing passage of water vapor through the pores of said polyvinylidene fluoride layer, comprising a hydrophilic layer substantially on the surface of the polyvinylidene fluoride layer.
Claim 3
Dependent Claim
21 words
A composite membrane as in claim 1 wherein the mean pore diameter of the hydrophobic layer is less than 0.5 μm.
Claim 4
Dependent Claim
21 words
A composite membrane as in claim 2 wherein the mean pore diameter of the hydrophilic layer is less than 0.5 μm.
Claim 5
Dependent Claim
13 words
A composite membrane as in claim 1 wherein said hydrophilic layer is porous.
Claim 6
Dependent Claim
27 words
A composite membrane as in claim 4 wherein the average pore size of the hydrophilic layer is less than the average pore size of the hydrophobic layer.
Claim 7
Dependent Claim
20 words
A composite membrane as in claim 4 wherein the hydrophilic layer is a mixture of cellulose acetate and cellulose nitrate.
Claim 8
Dependent Claim
14 words
A composite membrane as in claim 4 wherein the hydrophilic layer is cellulose acetate.
Claim 9
Dependent Claim
13 words
A composite membrane as in claim 4 wherein the hydrophilic layer is polysulfone.
Claim 10
Dependent Claim
13 words
A composite membrane as in claim 1 wherein said hydrophilic material is non-porous.
Claim 11
Dependent Claim
80 words
A composite membrane for applications where unidirectional passage of water vapor is required comprising a layer of porous, hydrophobic, fluoropolymer plastic through which aqueous solutions are prevented from passing but through which water can pass in the form of a vapor and means for preventing an aqueous solution from intruding within the pores of said fluoropolymer plastic while allowing passage of water vapor through the pores comprising a layer of hydrophilic material substantially on the surface of the fluoropolymer layer.
Claim 12
Dependent Claim
80 words
A composite membrane for applications where unidirectional passage of water vapor is required comprising a layer of porous, hydrophobic, fluoropolymer plastic through which aqueous solutions are prevented from passing but through which water can pass in the form of a vapor and means for preventing an aqueous solution from intruding within the pores of said fluoropolymer plastic while allowing passage of water vapor through the pores comprising a layer of hydrophilic material substantially on the surface of the fluoropolymer layer.
Claim 13
Dependent Claim
74 words
A composite membrane for applications where unidirectional passage of water vapor is required comprising a layer of porous, nonwettable to aqueous solutions, hydrophobic, fluoropolymer through which water can pass only in the form of a vapor and means for preventing an aqueous solution from intruding within the pores of said fluoropolymer while allowing passage of water vapor through the pores comprising a layer of hydrophilic material substantially on the surface of the hydrophobic layer.
Claim 14
Dependent Claim
74 words
A composite membrane for applications where unidirectional passage of water vapor is required comprising a layer of porous, nonwettable to aqueous solutions, hydrophobic, fluoropolymer through which water can pass only in the form of a vapor and means for preventing an aqueous solution from intruding within the pores of said fluoropolymer while allowing passage of water vapor through the pores comprising a layer of hydrophilic material substantially on the surface of the hydrophobic layer.
Claim 15
Dependent Claim
13 words
A composite membrane as in claim 11, wherein said hydrophilic layer is porous.
Claim 16
Dependent Claim
27 words
A composite membrane as in claim 12 wherein the average pore size of the hydrophilic layer is less than the average pore size of the hydrophobic layer.
Claim 17
Dependent Claim
20 words
A composite membrane as in claim 12 wherein the hydrophilic layer is a mixture of cellulose acetate and cellulose nitrate.
Claim 18
Dependent Claim
14 words
A composite membrane as in claim 12 wherein the hydrophilic layer is cellulose acetate.
Claim 19
Dependent Claim
13 words
A composite membrane as in claim 12 wherein the hydrophilic layer is polysulfone.
Claim 20
Dependent Claim
21 words
A composite membrane as in claim 11 wherein the mean pore diameter of the hydrophobic layer is less than 0.5 μm.
Claim 21
Dependent Claim
27 words
A composite membrane as in claim 11 wherein the mean pore diameter of the hydrophobic layer is within a range of about 0.025 μm. to 0.5 μm.
Claim 22
Dependent Claim
14 words
A composite membrane as in claim 11 wherein the hydrophobic layer comprises substantially polytetrafluoro-ethylene.
Claim 23
Dependent Claim
15 words
A composite membrane as in claim 11 wherein said hydrophobic layer comprises substantially polyvinylidene fluoride.
Claim 24
Dependent Claim
13 words
A composite membrane as in claim 20 wherein said hydrophilic layer is nonporous.
Claim 25
Dependent Claim
88 words
A layered membrane suitable for use in applications where unidirectional passage of water vapor is desired therethrough comprising: a microporous hydrophobic layer through which water can pass in the form of a vapor but is prevented from passing in the form of a liquid; and means for preventing liquids, including salt-bearing liquids, from intruding within the pores of said microporous hydrophobic layer while allowing passage of water vapor through the pores of said hydrophobic layer, comprising a hydrophilic layer on substantially the surface of said microporous hydrophobic layer.
Claim 26
Dependent Claim
88 words
A layered membrane suitable for use in applications where unidirectional passage of water vapor is desired therethrough comprising: a microporous hydrophobic layer through which water can pass in the form of a vapor but is prevented from passing in the form of a liquid; and means for preventing liquids, including salt-bearing liquids, from intruding within the pores of said microporous hydrophobic layer while allowing passage of water vapor through the pores of said hydrophobic layer, comprising a hydrophilic layer on substantially the surface of said microporous hydrophobic layer.
Claim 27
Dependent Claim
13 words
A layered membrane as in claim 22 wherein said hydrophilic layer is porous.
Claim 28
Dependent Claim
27 words
A layered membrane as in claim 23 wherein the average pore size of the hydrophilic layer is less than the average pore size of the hydrophobic layer.
Claim 29
Dependent Claim
20 words
A layered membrane as in claim 23 wherein the hydrophilic layer is a mixture of cellulose acetate and cellulose nitrate.
Claim 30
Dependent Claim
14 words
A layered membrane as in claim 23 wherein the hydrophilic layer is cellulose acetate.
Claim 31
Dependent Claim
13 words
A layered membrane as in claim 22 wherein the hydrophilic layer is polysulfone.
Claim 32
Dependent Claim
21 words
A layered membrane as in claim 22 wherein the mean pore diameter of the hydrophobic layer is less than 0.5 μm.
Claim 33
Dependent Claim
27 words
A layered membrane as in claim 22 wherein the mean pore diameter of the hydrophobic layer is within a range of about 0.25 μm to 0.5 μm.
Claim 34
Dependent Claim
14 words
A layered membrane as in claim 22 wherein the hydrophobic layer comprises substantially polytetralfluoro-ethylene.
Claim 35
Dependent Claim
15 words
A layered membrane as in claim 22 wherein said hydrophobic layer comprises substantially polyvinylidene fluoride.
Claim 36
Dependent Claim
13 words
A layered membrane as in claim 31 wherein said hydrophilic layer is non-porous.
References Cited (Backward Citations)
US2972586A
Cited
US3005728A
Cited
US3405058A
Cited
US3556305A
Cited
US3615024A
Cited
US3580841A
Cited
US4067805A
Cited
US3950249A
Cited
US4311594A
Cited
US4203848A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-09-25 | 1988-03-26 | 1988-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-25 | 1992-03-26 | 1992-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-25 | 1996-03-26 | 1996-09-25 | $7700.00 | Window Closed / Lapsed |