Liquid purification or separation – Plural distinct separators – Filters
Patent
1995-03-08
1998-06-02
Popovics, Robert
Liquid purification or separation
Plural distinct separators
Filters
210391, 210396, 210402, 210406, 210408, 210409, 210417, B01D 3306, B01D 3300
Patent
active
057593973
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an arrangement for separating solid particles from a liquid mixture, comprising a hollow filter body with a wall of filter material, and a container for the liquid mixture which is to be separated, the filter body being arranged partially immersed in the liquid mixture. A drive member is designed to rotate the filter body about a horizontal axle, so that the wall of filter material is rotated up and down through the surface of the liquid mixture. A pressure source is designed to generate a higher pressure on the outside of the filter body than on the inside of the filter body, so that a fine fraction of the liquid mixture is forced through the filter material, while a cake of solid particles is deposited on the filter material and accompanies the latter up over the liquid mixture during rotation of the filter body. A cake-removal member is designed to take off a layer of the cake from the filter material above the liquid mixture, so that a liquid-permeable coating of solid particles is left on the filter material which is moved down into the liquid mixture during rotation of the filter body. The arrangement moreover comprises a discharging member for discharging the said removed cake layer from the arrangement, and means for spraying the filter material with jets of liquid above the liquid mixture for the purpose of removing the said coating of solid particles for renewal thereof.
2. Description of the Prior Art
Arrangements of this type are used in the paper pulp industry, especially for purifying white liquor, green liquor and lime sludge (calcium carbonate) in causticization processes.
The renewal of the said coating of solid particles is necessary due to the fact that the liquid-permeability of the coating deteriorates after a certain running period. In a known arrangement of this type, which consists of a drum filter for purifying lime sludge, the coating of solid particles is renewed by the spraying means removing a strip of the coating from the filter drum. A jet of liquid from the spraying means is in this case moved to and fro axially along the filter drum on its down side and between the cake-removal member and the liquid mixture. A disadvantage of the known arrangement is that the spraying means must be designed to spray the jet of liquid at a high pressure in order to guarantee to some extent the removal of the coating, since the coating is especially dry and hard between the cake-removal member and the liquid mixture. In practice, the spraying means has to be designed to generate two continuously movable jets of liquid, a first jet of liquid for crushing and breaking up the coating, and a second jet of liquid for finally cleaning the filter drum surface thus exposed. Despite the use of the said two jets of liquid, the removal of the coating is not entirely reliable.
SUMMARY OF THE INVENTION
The aim of the present invention is to provide an arrangement of the type in question here, by means of which the renewal of the said coating of solid particles can be effected with the aid of a single spraying means in a reliable manner.
This aim is achieved by means of an arrangement of the type described in the introduction, which is distinguished essentially in that the spraying means is designed to spray jets of liquid in at least one spray zone, through which a part of the wall of filter material passes upwards during rotation of the filter body, so that the whole cake of coarse particles, including the coating, is removed from the wall part of filter material by the jets of liquid when the spraying means is actuated during rotation of the filter body.
Thus, the spraying means will spray jets of liquid on the part of the cake which is being moved upwards from the liquid mixture and which, including the coating under the cake, is relatively wet and porous, which affords the advantage that the wet, porous coating is easily removed from the filter material by the jets of liquid.
The spray zone is preferably arrange
REFERENCES:
patent: 1804934 (1931-05-01), Hoyt
patent: 2839194 (1958-06-01), Lopker et al.
patent: 3169706 (1965-02-01), Ross
patent: 3521751 (1970-07-01), Holthuis
patent: 4995991 (1991-02-01), Ljokkoi et al.
patent: 5374360 (1994-12-01), Weis
patent: 5423977 (1995-06-01), Aoki et al.
patent: 5470472 (1995-11-01), Baird et al.
C.F. Cornell, "Current Recausticizing Practice, Part 1; 1992 Kraft Recovery Operations Short Course (Orlando)", pp. 29-57.
Larsson Per Helge
Nordlof Jonas Hans Olov
Caustec AB
Popovics Robert
LandOfFree
Filter with spray cake removal means does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Filter with spray cake removal means, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Filter with spray cake removal means will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1455508