Liquid purification or separation – Filter – Movable medium
Patent
1999-02-10
2000-05-23
Upton, Christopher
Liquid purification or separation
Filter
Movable medium
2104331, 210541, B01D 33067
Patent
active
060656085
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to an apparatus or filtering liquids, comprising a hollow body having a wall of filter material, and a stationary support structure on which the hollow body is journalled by means of a first bearing at a first side of the hollow body and a second bearing at a second side of the hollow body opposite said first side, such that the hollow body is rotatable about a horizontal axis, the hollow body forming a circumferential liquid impervious wall, at said second side, extending axially a distance from said wall of filter material and defining a circular opening, which is coaxial with said axis, the support structure forming a liquid supplying chamber partly defined by a stationary circumferential wall, which is close to but spaced from said liquid impervious wall and which at least partly extends along the boundary of said circular opening of the hollow body. There is an inlet to said supplying chamber for a liquid to be filtered. Sealing means are arranged to seal between said circumferential liquid impervious wall and said stationary circumferential wall of the supplying chamber, whereby liquid to be filtered entering said inlet during operation passes the supplying chamber and said circular opening into the interior of the hollow body, from which a filtrate penetrates the wall of filter material. A coarse fraction discharge means is arranged to convey a coarse fraction of the liquid to be filtered from the interior of the hollow body through said supplying chamber out of the apparatus, and a filtrate container is arranged to receive filtrate from the hollow body through said upper opening and has an outlet for discharging filtrate.
This type of prior art filtering apparatus, in which the liquid to be filtered is supplied to the interior of the hollow body so that filtrate flows by gravity through the filter material in the direction out of the hollow body, is suited for filtering a variety of liquids, such as raw water, polluted water and in particular suspensions developed in the pulp and paper processing industry. Coarse particles of undesired material, such as fine fibres and fibre fragments, deposit on the filter material inside the hollow body during operation and are usually removed from top of the hollow body by means of spray nozzles operating from outside the hollow body, so that the coarse fraction discharge means may convey the removed particles out of the apparatus. An important use of this type of filtering apparatus is to clean warm so-called white water obtained in the pulp and paper processing industry. Cleaned warm white-water is re-used as liquid for operating fine cleansing spray nozzles in various parts of pulp and paper processing systems, which reduces the consumption of fresh water and energy.
A problem of this type of filtering apparatus, however, is that the function of the sealing means is difficult to survey. Normally, a minor insignificant liquid leakage past the sealing means occurs during operation, which is acceptable. On the other hand, if the sealing means is more or less damaged or worn the leakage of unfiltered liquid past the sealing means can be quite significant, which of course is not acceptable. As a result, a mal-functioning sealing means can be in operation for a while, so that unfiltered liquid escapes past the sealing means and pollutes the filtrate in the filtrate container. In the case of filtering white-water, fibre residues in the filtrate could clogg said fine cleansing spray nozzles resulting in disturbances in the pulp or paper making process.
The object of the present invention is to provide a filtering apparatus of the above described type, in which the risk of unfiltered liquid polluting the filtrate is eliminated.
This object is fulfilled by the apparatus presented initially, which is characterised in that wall means are arranged to prevent unfiltered liquid leaking past the sealing means from entering the filtrate container.
Said wall means preferably comprises a leakage liquid guidi
REFERENCES:
patent: 3797663 (1974-03-01), Borrdale
patent: 4294700 (1981-10-01), Casper
patent: 4821536 (1989-04-01), Bardsley
patent: 5667680 (1997-09-01), Haeffner
patent: 5733450 (1998-03-01), Langner
Nordic Water Products AB
Upton Christopher
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