Patent US3853756A successfully refreshed from Google Patents.
US3853756A
Expired / Lapsed
US
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Reverse pressure cleaning of supported semipermeable membranes
Assignee: Graftech Technology LLC
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Filing: 1973-02-12
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Granted: 1974-12-10
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Expires: 1993-02-12
Abstract
Abstract Foulants are removed from the surface of a supported semipermeable membrane by (A) contacting the feed side of a semipermeable membrane, supported by a wall of a module comprising resin bonded filler particles, with a continuous stream of liquid feed solution under a driving pressure of up to about 1,000 psi, (B) applying a back pressure, on the support side of the membrane, of up to about 50 psi greater than the driving pressure, to cause a backflow of liquid through the membrane, from the support side to the feed side, and (C) flushing the solution containing the concentrated foulants from the feed side membrane surface.
Inventors
- 👤 R Stana
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:49
CPC Classifications
B; B01; B01D; B01D65/00; B01D65/02; B01D61/00; B01D61/14; B01D61/145; B01D63/00; B01D63/06; B01D63/062; B01D2321/00; B01D2321/04
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
231 words
A METHOD OF CLEANING FOULANTS FROM THE SURFACE OF A SUPPORTED SEMIPERMEABLE MEMBRANE HAVING A FEED SIDE AND A SUPPORT SIDE, COMPRISING THE STEPS OF: A. CONTACTING THE FEED SIDE OF A POROUS SEMIPERMEABLE MEMBRANE, SUPPORTED BY AN INTEGRALLY BONDED TO THE WALL OF A MODULE COMPRISING RESIN BONDED FILLER PARTICLES, FOR A PERIOD OF TIME, WITH A CONTINOUS STREAM OF LIQUID FEED SOLUTION CONTAINING FOULANTS UNDER A PRESSURE OF UP TO ABOUT 1000 PSI, WHEREIN SAID FOULANTS CONCENTRATE AT THE MEMBRANE FEED SIDE SURFACE; B. RELEASUNG THE PRESSURE ON THE FEED SIDE OF THE MEMBRANE, FOR A PERIOD OF TIME OF BETWEEN ABOUT 5 TO ABOUT 30 SECONDS, AND ACTIVATING A MEANS TO CAUSE A BACK PRESSURE ON THE SUPPORT SIDE OF THE MEMBRANE OF BETWEEN ABOUT 2 TO 50 PSI TO CAUSE THE BACKFLOW OF LIQUID THROUGH THE MEMBRANE OF BETWEEN ABOUT 3-60 GAL/SQ. FT/DAY FROM THE SUPPORT SIDE TO THE FEED SIDE OF THE MEMBRANE, WITHOUT ALTERING THE MEMBRANE PORE STRUCTURE, SAID BACKFLOW BEING EFFECTIVE TO REMOVE FOULANTS CONCENTRATED AT THE MEMBRANE FEED SIDE SURFACE; C. APPLYING A DRIVING PRESSURE OF UP TO ABOUT 1,000 PSI TO THE FEED SOLUTION TO FLUSH THE FOULANTS FROM THE FEED SIDE OF THE MEMBRANE WHEREIN THE TIME CYCLE RATIO OF DRIVING PRESSURE TIME: BACK PRESSURE TIME IS OVER 2:1, AND D. REPEATING STEP (B) AND THEN STEP (C0 AT LEAST TWICE;
Claim 2
Independent Claim
231 words
A METHOD OF CLEANING FOULANTS FROM THE SURFACE OF A SUPPORTED SEMIPERMEABLE MEMBRANE HAVING A FEED SIDE AND A SUPPORT SIDE, COMPRISING THE STEPS OF: A. CONTACTING THE FEED SIDE OF A POROUS SEMIPERMEABLE MEMBRANE, SUPPORTED BY AN INTEGRALLY BONDED TO THE WALL OF A MODULE COMPRISING RESIN BONDED FILLER PARTICLES, FOR A PERIOD OF TIME, WITH A CONTINOUS STREAM OF LIQUID FEED SOLUTION CONTAINING FOULANTS UNDER A PRESSURE OF UP TO ABOUT 1000 PSI, WHEREIN SAID FOULANTS CONCENTRATE AT THE MEMBRANE FEED SIDE SURFACE; B. RELEASUNG THE PRESSURE ON THE FEED SIDE OF THE MEMBRANE, FOR A PERIOD OF TIME OF BETWEEN ABOUT 5 TO ABOUT 30 SECONDS, AND ACTIVATING A MEANS TO CAUSE A BACK PRESSURE ON THE SUPPORT SIDE OF THE MEMBRANE OF BETWEEN ABOUT 2 TO 50 PSI TO CAUSE THE BACKFLOW OF LIQUID THROUGH THE MEMBRANE OF BETWEEN ABOUT 3-60 GAL/SQ. FT/DAY FROM THE SUPPORT SIDE TO THE FEED SIDE OF THE MEMBRANE, WITHOUT ALTERING THE MEMBRANE PORE STRUCTURE, SAID BACKFLOW BEING EFFECTIVE TO REMOVE FOULANTS CONCENTRATED AT THE MEMBRANE FEED SIDE SURFACE; C. APPLYING A DRIVING PRESSURE OF UP TO ABOUT 1,000 PSI TO THE FEED SOLUTION TO FLUSH THE FOULANTS FROM THE FEED SIDE OF THE MEMBRANE WHEREIN THE TIME CYCLE RATIO OF DRIVING PRESSURE TIME: BACK PRESSURE TIME IS OVER 2:1, AND D. REPEATING STEP (B) AND THEN STEP (C0 AT LEAST TWICE;
Claim 3
Dependent Claim
31 words
The method of claim 1 wherein the module is a tubular module having at least one interior axial feed bore therethrough, said membrane being supported by the interior feed bore wall.
Claim 4
Dependent Claim
19 words
The method of claim 2, wherein the means to apply backpressure is a liquid reservoir disposed above the membrane.
Claim 5
Dependent Claim
14 words
The method of claim 2, wherein the means to apply backpressure is a pump.
Claim 6
Dependent Claim
26 words
The method of claim 2 wherein the backpressure is applied in a time cycle ratio of driving pressure time; backpressure time of about 2 to 30:1.
Claim 7
Dependent Claim
62 words
The method of claim 5 wherein the module resin is selected from the group consisting of epoxy resin, polyester resin, phenolic resin and silicone resin, the module filler is selected from the group consisting of sand, quartz, zircon, alumina, limestone, beryl and mixtures thereof and the membrane is selected from the group consisting of polysulfone, polyethylene and ether and ester cellulosic derivatives.
Claim 8
Dependent Claim
39 words
The method of claim 5, wherein the driving pressure is between about 15 to 250 psi and the membrane is selected from the group consisting of polysulfone, polyethylene, cellulose acetate, cellulose propionate, cellulose butyrate, methyl cellulose and ethyl cellulose.
Claim 9
Dependent Claim
66 words
The method of claim 7 wherein the backpressure is applied in a time cycle ratio of driving pressure time: backpressure time of about 3 to 9:1, the membrane is modified cellulose acetate having a relatively uniform cross section, the module resin is phenolic resin and the module filler is sand, said resin constituting about 2 to 18 weight percent based on resin coated filler particle weight.
Claim 10
Dependent Claim
37 words
The method of claim 7 wherein the membrane is an ultrafiltration membrane having an average pore size diameter of between about 10 to 150 angstrom units, and the feed solution has a high concentrAtion of suspended solids.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-09 | 1978-06-10 | 1978-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-09 | 1982-06-10 | 1982-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-09 | 1986-06-10 | 1986-12-10 | $7700.00 | Window Closed / Lapsed |