EP0079040A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method and apparatus for increasing the cross-flow filtration fluxes of liquids containing suspended solids
Assignee: Hydronautics Inc
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Filing: 1982-11-03
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Granted: —
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Expires: 2002-11-03
Abstract
Abstract A method of increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall comprises the steps of: (a) flowing the liquid through the filter tube and permeating the liquid through the tube wall by establishing a transmembrane pressure within the tube, thereby depositing at least a portion of the solids on the inner surface of the tube as a sludge layer; (b) periodically reducing the transmembrane pressure to about zero for periods not in excess of about 2 minutes thereby periodically permitting enhanced erosion of the sludge layer so as to reduce its thickness; and (c) re-establishing the transmembrane pressure after each intermittent reduction, whereby the time-averaged filtration flux is increased. Typically, the transmembrane pressure is established by creating a net positive pressure within the filter tube, and the periodic reduction of the transmembrane pressure is achieved by periodically reducing the net positive pressure to about zero. Also disclosed is a method of increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising the steps of: (a) flowing the liquid through the fitter tube and permeating the liquid through the tube wall by establishing a transmembrane pressure within the tube, thereby depositing at least a portion of the solids on the inner surface of the tube as a sludge layer; (b) periodically increasing the circulation velocity of the liquid flowing lengthwise through the fitter tube to a value in excess of about 7 fps, preferably between about 10 and about 20 fps, and more preferably to about 15 fps thereby permitting enhanced erosion of the sludge layer so as to reduce its thickness; and (c) reducing the circulation velocity after each intermittent increase, whereby the time-averaged filtration flux is increased. Apparatus is also disclosed for practicing the methods of the invention.
Inventors
- 👤 Marshall P. Tulin
- 👤 Han Lieh Liu
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 03:45
CPC Classifications
B; B01; B01D; B01D63/00; B01D63/06; B01D63/069; B01D61/00; B01D61/14; B01D61/147; B01D2313/00; B01D2313/18; B01D2315/00; B01D2315/10
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
117 words
A method of increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising the steps of: a) flowing the liquid through the filter tube and permeating the liquid through the tube wall by establishing a transmembrane pressure within the tube, thereby depositing at least a portion of the solids on the inner surface of the tube as a sludge layer; b) periodically reducing the transmembrane pressure to about zero for periods not in excess of about 2 minutes, thereby permitting enhanced erosion of the sludge layer so as to reduce its thickness; and c) re-establishing the transmembrane pressure after each intermittent reduction, whereby the time-averaged filtration flux is increased.
Claim 2
Independent Claim
117 words
A method of increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising the steps of: a) flowing the liquid through the filter tube and permeating the liquid through the tube wall by establishing a transmembrane pressure within the tube, thereby depositing at least a portion of the solids on the inner surface of the tube as a sludge layer; b) periodically reducing the transmembrane pressure to about zero for periods not in excess of about 2 minutes, thereby permitting enhanced erosion of the sludge layer so as to reduce its thickness; and c) re-establishing the transmembrane pressure after each intermittent reduction, whereby the time-averaged filtration flux is increased.
Claim 3
Dependent Claim
44 words
A method as claimed in claim 1, wherein the transmembrane pressure is established by creating a net positive pressure within the filter tube, and wherein the periodic reduction of the transmembrane pressure is achieved by periodically reducing said net positive pressure to about zero.
Claim 4
Dependent Claim
67 words
A method as claimed in claim 1 or 2, further comprising the steps of collecting the liquid permeated through the filter tube wall in a closed jacket surrounding the filter tube in a manner adapted to establish a pressure differential between the liquid in the jacket and the liquid in the tube, and removing the collected liquid from the jacket via a port extending through the jacket.
Claim 5
Dependent Claim
83 words
A method as claimed in claim 3, further comprising the steps of periodically reducing the pressure differential between the jacket and the interior of the filter tube to about zero for periods not in excess of about 2 minutes by closing the port in the permeate-collecting jacket, thereby permitting enhanced erosion of the sludge layer so as to further reduce its thickness, and re-establishing the pressure differential after each intermittent reduction by opening the port, whereby the time-averaged filtration flux is further increased.
Claim 6
Dependent Claim
59 words
A method as claimed in claim 1, 2 or 4, further comprising the step of periodically increasing the circulation velocity of the liquid flowing lengthwise through the filter tube coincidentally with the periods during which the transmembrane pressure is reduced to about zero, the circulation velocity being increased to a value in excess of about 7 ft. per sec.
Claim 7
Dependent Claim
33 words
A method as claimed in claim 5, wherein the circulation velocity is periodically increased to a value within the range of from about 10 ft. per sec. to about 20 ft. per sec.
Claim 8
Dependent Claim
23 words
A method as claimed in claim 5, wherein the circulation velocity is periodically increased to a value of about 15 ft. per sec.
Claim 9
Dependent Claim
48 words
A method as claimed in claim 1, 2 or 4, wherein the transmembrane pressure is periodically reduced to about zero for periods within the range of from 5 seconds to about 60 seconds, and wherein the time intervals between said periodic reductions do not exceed about 20 minutes.
Claim 10
Dependent Claim
23 words
A method as claimed in claim 8, wherein the transmembrane pressure is periodically reduced to about zero for periods of about 30 seconds.
Claim 11
Dependent Claim
28 words
A method as claimed in claim 8, wherein the time intervals between said periodic reductions are within the range of from about 1 minute to about 10 minutes.
Claim 12
Independent Claim
239 words
A method of increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising the steps of: a) flowing the liquid through the filter tube and permeating the liquid through the tube wall by establishing a transmembrane pressure within the tube, thereby depositing at least a portion of the solids on the inner surface of the tube as a sludge layer; b) collecting the liquid permeated through the filter tube wall in a closed jacket surrounding the filter tube in a manner adapted to establish a pressure differential between the liquid in the jacket and the liquid in the tube, and removing the collected liquid from the jacket via a port extending through the jacket; c) periodically reducing the pressure differential between the jacket and the interior of the filter tube to about zero for periods not in excess of about 2 minutes by closing the port in the permeate-collecting jacket, thereby permitting enhanced erosion of the sludge layer so as to reduce its thickness, and re-establishing - the pressure differential after each intermittent reduction by opening the port; and d) periodically increasing the circulation velocity of the liquid flowing lengthwise through the filter tube coincidentally with the periods during which the pressure differential is reduced to about zero, the circulation velocity being increased to a value in excess of about 7 ft. per sec., whereby the time-averaged filtration flux is increased.
Claim 13
Independent Claim
239 words
A method of increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising the steps of: a) flowing the liquid through the filter tube and permeating the liquid through the tube wall by establishing a transmembrane pressure within the tube, thereby depositing at least a portion of the solids on the inner surface of the tube as a sludge layer; b) collecting the liquid permeated through the filter tube wall in a closed jacket surrounding the filter tube in a manner adapted to establish a pressure differential between the liquid in the jacket and the liquid in the tube, and removing the collected liquid from the jacket via a port extending through the jacket; c) periodically reducing the pressure differential between the jacket and the interior of the filter tube to about zero for periods not in excess of about 2 minutes by closing the port in the permeate-collecting jacket, thereby permitting enhanced erosion of the sludge layer so as to reduce its thickness, and re-establishing - the pressure differential after each intermittent reduction by opening the port; and d) periodically increasing the circulation velocity of the liquid flowing lengthwise through the filter tube coincidentally with the periods during which the pressure differential is reduced to about zero, the circulation velocity being increased to a value in excess of about 7 ft. per sec., whereby the time-averaged filtration flux is increased.
Claim 14
Dependent Claim
43 words
A method as claimed in claim 4 or 11, wherein the pressure differential between the jacket and the interior of the filter tube is periodically reduced to about zero for periods within the range of from about 5 seconds to about 60 seconds.
Claim 15
Dependent Claim
36 words
A method as claimed in claim 11, wherein the circulation velocity of the liquid is periodically increased to a value within the range of from about 10 ft. per sec. to about 20 ft. per sec.
Claim 16
Dependent Claim
42 words
A method as claimed in claim 1, 2, 4, or 11, wherein the porous filter tube is made of an extrudable thermoplastic composition selected from the group consisting of nylon and polyethylene and has a wall about one (1) millimeter in thickness.
Claim 17
Dependent Claim
34 words
A method as claimed in claim 1, 2, 4, or 11 including the step of pretreating the liquid prior to flowing it through the filter tube so as to render the liquid substantially cohesionless.
Claim 18
Dependent Claim
30 words
A method as claimed in claim 5, including the step of pretreating the liquid prior to flowing it through the filter tube so as to render the liquid substantially cohesionless.
Claim 19
Independent Claim
133 words
A method of increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising the steps of: a) flowing the liquid through the filter tube and permeating the liquid through the tube wall by establishing a transmembrane pressure within the tube, thereby depositing at least a portion of the solids on the inner surface of the tube as a sludge layer; b) periodically increasing the circulation velocity of the liquid flowing lengthwise through the filter tube to a value in excess of 7 ft. per sec. for intervals not in excess of about 2 minutes, thereby permitting enhanced erosion of the sludge layer so as to reduce its thickness; and c) reducing the circulation velocity after each intermittent increase, whereby the time-averaged filtration flux is increased.
Claim 20
Independent Claim
133 words
A method of increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising the steps of: a) flowing the liquid through the filter tube and permeating the liquid through the tube wall by establishing a transmembrane pressure within the tube, thereby depositing at least a portion of the solids on the inner surface of the tube as a sludge layer; b) periodically increasing the circulation velocity of the liquid flowing lengthwise through the filter tube to a value in excess of 7 ft. per sec. for intervals not in excess of about 2 minutes, thereby permitting enhanced erosion of the sludge layer so as to reduce its thickness; and c) reducing the circulation velocity after each intermittent increase, whereby the time-averaged filtration flux is increased.
Claim 21
Dependent Claim
33 words
A method as claimed in claim 17, wherein the circulation velocity is periodically increased to a value within the range of from about 10 ft. per sec. to about 20 ft. per sec.
Claim 22
Dependent Claim
20 words
A method as claimed in claim 17, wherein the circulation velocity is periodically increased to about 15 ft. per sec.
Claim 23
Dependent Claim
31 words
A method as claimed in claim 17, 18 or 19, wherein the circulation velocity is periodically increased for intervals within the range of from about 5 seconds to about 60 seconds.
Claim 24
Dependent Claim
23 words
A method as claimed in claim 17, 18 or 19, wherein the circulation velocity is periodically increased for intervals of about 30 seconds.
Claim 25
Dependent Claim
117 words
Apparatus for increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising: a) at least one porous filter tube; b) means for flowing the liquid through the filter tube; c) means for establishing a transmembrane pressure within the filter tube, thereby affecting permeation of the liquid through the tube wall, causing at least a portion of the solids to be deposited on the inner surface of the tube as a sludge layer; and d) means for periodically reducing the transmembrane pressure to about zero and then re-establishing it, thereby permitting periodic enhanced erosion of the sludge layer so as to reduce its thickness and increase the time-averaged filtration flux.
Claim 26
Dependent Claim
117 words
Apparatus for increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising: a) at least one porous filter tube; b) means for flowing the liquid through the filter tube; c) means for establishing a transmembrane pressure within the filter tube, thereby affecting permeation of the liquid through the tube wall, causing at least a portion of the solids to be deposited on the inner surface of the tube as a sludge layer; and d) means for periodically reducing the transmembrane pressure to about zero and then re-establishing it, thereby permitting periodic enhanced erosion of the sludge layer so as to reduce its thickness and increase the time-averaged filtration flux.
Claim 27
Dependent Claim
86 words
Apparatus as claimed in claim 22, wherein said means for establishing a transmembrane pressure within the filter tube includes a normally partially closed valve located at the downstream end of the filter tube for creating a net positive pressure in the tube, and wherein said means for periodically reducing the transmembrane pressure to about zero and then re-establishing it includes a time-regulated actuating means operatively connected to said valve for periodically opening said valve, thereby reducing the net positive pressure in the tube to essentially zero.
Claim 28
Dependent Claim
97 words
Apparatus as claimed in claims 22 or 23, wherein said means for establishing the transmembrane pressure includes closed jacket means surrounding the filter tube for collecting the liquid permeated through the filter tube wall and establishing a pressure differential between the liquid in the jacket means and the liquid in the tube, said jacket means having a port for the removal of collected liquid; and wherein said means periodically reducing the transmembrane pressure includes means for periodically reducing said pressure differential to about zero and then re-establishing it, thereby periodically reducing the transmembrane pressure to about zero.
Claim 29
Dependent Claim
51 words
Apparatus as claimed in claim 24, wherein said means for periodically reducing said pressure differential to about zero and then re-establishing it includes a time-regulated valve situated in said port for periodically closing and re-opening said port, whereby said pressure differential is reduced to about zero when said port is closed.
Claim 30
Dependent Claim
60 words
Apparatus as claimed in claim 22, further comprising means for periodically increasing the velocity of the liquid flowing lengthwise through the filter tube coincidentally with the periods during which the transmembrane pressure is reduced to about zero, the velocity being increased to a value in excess of about 7 ft. per sec., whereby the time-averaged filtration flux is further increased.
Claim 31
Dependent Claim
30 words
Apparatus as claimed in claim 22, wherein the apparatus includes a plurality of said porous filter tubes or tube bundles fluidly connected in series to form a tube module system.
Claim 32
Dependent Claim
21 words
Apparatus as claimed in claim 27, wherein the apparatus includes a plurality of said tube module systems fluidly connected in parallel.
Claim 33
Dependent Claim
35 words
Apparatus as claimed in claim 28, wherein the apparatus includes means for sequentially reducing the transmembrane pressure in each individual tube module system while maintaing the normal transmembrane pressure in the other tube module systems.
Claim 34
Dependent Claim
91 words
Apparatus as claimed in claim 29, wherein said means for establishing the transmembrane pressure includes a plurality of normally partially closed filtration control valves, one filtration control valve being located at the downstream end of each of said tube modules, and wherein said means for sequentially reducing the transmembrane pressure comprises a plurality of back pressure relief valves, one back pressure relief valve being located at the downstream end of each of said tube modules and being fluidly connected in parallel with the associated filtration control valve for said tube module.
Claim 35
Dependent Claim
134 words
Apparatus for increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising: a) at least one porous filter tube; b) means for flowing the liquid through the filter tube; c) means for establishing a transmembrane pressure within the filter tube, thereby effecting permeation of the liquid through the tube wall, causing at least a portion of the solids to be deposited on the inner surface of the tube as a slude layer; and d) means for periodically increasing the circulation velocity of the liquid flowing lengthwise through the filter tube to a value in excess of about 7 ft. per sec. - and thereafter reducing it, thereby permitting enhanced erosion of the sludge layer so as to reduce its thickness and increase the time-averaged filtration flux.
Claim 36
Dependent Claim
134 words
Apparatus for increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising: a) at least one porous filter tube; b) means for flowing the liquid through the filter tube; c) means for establishing a transmembrane pressure within the filter tube, thereby effecting permeation of the liquid through the tube wall, causing at least a portion of the solids to be deposited on the inner surface of the tube as a slude layer; and d) means for periodically increasing the circulation velocity of the liquid flowing lengthwise through the filter tube to a value in excess of about 7 ft. per sec. - and thereafter reducing it, thereby permitting enhanced erosion of the sludge layer so as to reduce its thickness and increase the time-averaged filtration flux.
References Cited (Backward Citations)
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