Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Patent
1995-02-22
1997-07-01
Fortuna, Ana
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
210650, 210791, 21033301, 2103331, 21032169, B01D 6100
Patent
active
056434553
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to concentration of solids in a suspension using a hollow fibre membrane and, in particular forms, to methods and apparatus for periodically cleaning by backwashing the hollow fibre membranes.
BACKGROUND ART
Prior art methods of concentrating solids in a liquid suspension are described in Australian patent specifications 576,424 and 582,968. The text and drawings of these specifications are incorporated herein by cross-reference. In that prior art, concentration is effected by a filter element that comprises a bundle of hollow, porous, polymeric fibres in a closed cartridge or shell. Polyurethane potting compound is used to hold the respective ends of the fibres in place within the cartridge without blocking the fibre lumens and to close off each end of the cartridge.
The transmembrane pressure differential necessary to effect concentration of the solids in the prior art is achieved by pressurising the feedstock which necessitates the use of pumps, other ancillary equipment and, of course, a closed filter cartridge.
Backwashing of such prior art concentrators involves increasing the pressure on both sides of the hollow fibres within the closed shell to a relatively high value before suddenly releasing that pressure on the shell side of the fibre walls to effect a sudden pressure differential across the walls which causes a backwash action.
DISCLOSURE OF THE INVENTION
It is an object of this invention to provide an improved method of using a reverse-flow mode to dislodge solids retained by filter elements to ensure rapid removal of those retained solids and in which the separation and dislodgement modes may be repeated for prolonged periods of time.
It is a further object of the present invention, in at least some embodiments, to provide a method of backwashing a hollow fibre filter which retains some of the features of the prior art, notably the use of a prior lower pressure gas to purge the lumens of liquid before using higher pressure gas to backwash the membrane but without the need to close the vessel before suddenly releasing the enclosed higher pressure. This improvement allows a simpler system, less subjected to repeated hydraulic shocks, and, in some embodiments, use of an open vessel with lowered pressure induced filtration.
Accordingly, in one broad form of the invention, there is provided a method of backwashing a plurality of hollow elongate fibres having microporous walls which have been subjected to a filtration operation wherein feed containing contaminant matter is applied to the exterior surface of said hollow fibres and filtrate (comprising that portion of the feed which penetrates the microporous walls of the fibres) is withdrawn from the ends of the lumens of the fibres, said method comprising: exterior surface of said fibres, generate a differential pressure (or transmembrane pressure) across said microporous walls sufficient to exceed the bubble point of said microporous walls whereby said fluid under pressure passes through said walls, substantial portions of contaminant matter lodged within and/or on said walls to be dislodged, feed to said exterior surface of said fibres.
Preferably step (b) is effected by applying pressure to said remaining filtrate whereby said remaining filtrate is passed in a reverse direction through said walls from a filtrate side to a feed side.
As an alternative preferred form, step (b) is effected by allowing said remaining filtrate to drain out of said lumens of its own volition.
In a particular form of said alternative preferred form, step (b) is effected by applying pressure to said remaining filtrate whereby said remaining filtrate is urged from said lumens.
In a particular preferred form of the invention, step (b) of draining the lumens of any remaining filtrate additionally includes the step of draining any remaining feed away from the exterior surface of the fibres whereby substantially no feed is in contact with the exterior surface of the fibres when the compressed air is applied.
After s
REFERENCES:
patent: 3853756 (1974-12-01), Stana
patent: 4540490 (1985-09-01), Shibata et al.
patent: 4655927 (1987-04-01), Ford
patent: 4767539 (1988-08-01), Ford
patent: 4844809 (1989-07-01), Ashina et al.
patent: 4931186 (1990-06-01), Ford et al.
patent: 4935143 (1990-06-01), Koop et al.
patent: 5024762 (1991-06-01), Ford et al.
patent: 5192456 (1993-03-01), Ishida et al.
patent: 5248424 (1993-09-01), Cote et al.
patent: 5484528 (1996-01-01), Yagi et al.
Darzi Jalel Michel
Doig Ian Dracup
Kopp Clinton Virgil
Streeton Robert John William
Fortuna Ana
Memtel Limited
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