Liquid purification or separation – Processes – Separating
Patent
1981-02-29
1982-11-09
Hruskoci, Peter A.
Liquid purification or separation
Processes
Separating
210772, 210797, 210332, 210409, B01D 4104
Patent
active
043583830
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of cleaning a filter surface in situ in a pressure filtering apparatus for liquids of the kind, in which the filter surface is at least generally vertically oriented and stationarily mounted in a filter housing for dividing the interior thereof into a suspension chamber and a filtrate chamber, between which chambers a substantial pressure difference is maintained during each filtering procedure in order to separate a filtrate from a liquid suspension supplied to the suspension chamber while leaving on the filter surface a moist coating at least mainly consisting of finely divided solid materials, the cleaning operation comprising the steps of first draining off both the suspension and the filtrate from the filter housing, subsequently drying the coating retained on the filter surface by supplying a gaseous drying medium, preferably air, to the suspension chamber and eventually causing the coating to be detached from the filter surface and to be discharged through an outlet opening located in the lower part of the suspension chamber, the detaching of the coating being promoted by supplying a gaseous cleansing medium, also preferably air, to the filter housing during at least a period of time representing the final stage of the cleaning operation.
The invention is also concerned with a pressure filtering apparatus for carrying out the method, in which apparatus a fine porous filter surface that is at least approximately vertically oriented is stationarily mounted in a filter housing in such a manner as to divide the interior thereof into a suspension chamber and a filtrate chamber each having individual outlet openings, with at least the outlet opening of the suspension chamber being disposed at a level below the filter surface, and in which apparatus at least one inlet opening for a gaseous medium under pressure is provided in the upper part of the suspension chamber.
Filtering liquid suspensions on an industrial scale involves many problems, and for more than a century a great number of more or less successful attempts have been made to solve them. In general, all these problems have one and the same cause, namely the difficulty of removing the coating, the so-called "cake", which is deposited on the filter surface during each filtering procedure and which, when it has reached a certain, frequently rather small thickness of perhaps only a few millimeters, will obstruct the liquid passage up to and through the filter surface so strongly that the capacity of the filter will become entirely insufficient for the existing need. In order to avoid an interruption of the filtering process, it is common practice in such a situation to provide a filtering apparatus with at least two alternatively operating groups of filter housings and to carry out the filtering procedure in one of said groups while acceptable operational conditions are being restored in the other, and vice versa.
Irrespective of whether this practice is applied or not there are only two ways of restoring acceptable operational conditions in the filter housings, namely either by replacing the clogged filter elements by clean and possibly new ones or by cleaning them in situ in the apparatus. Of these two alternatives the last-mentioned one is to be preferred in most cases, although of course, it cannot be applied unless the capacity of the filters actually can be regained to a substantial degree by such a cleaning operation.
During the last decades many different types of filter material have been developed, especially in the form of porous membranes, e.g. of plastics, as well as screens of metal, which are well suited for being cleaned in situ, particularly thanks to the fact that the filter surface is smooth and "fatty" or repellent so that a minimum of coating residues will remain attached after the filter cleaning operation. The invention is based on the use of such filter materials and especially of filter materials having a pore size of up to about 25 microns.
However, the possibility of cleaning the filter e
REFERENCES:
patent: 1348159 (1920-08-01), Down
patent: 1801539 (1931-04-01), Cannon
patent: 1967197 (1934-07-01), Besselievre
patent: 3794179 (1974-02-01), Doucet
patent: 3891551 (1975-06-01), Tiedemann
patent: 4089781 (1978-05-01), Asp
patent: 4113618 (1978-09-01), Koseki et al.
patent: 4217700 (1980-08-01), Muller
patent: 4265771 (1981-05-01), Lennartz et al.
Hruskoci Peter A.
Philpitt Fred
LandOfFree
Method of cleaning a filter surface in situ in a pressure filter does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of cleaning a filter surface in situ in a pressure filter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of cleaning a filter surface in situ in a pressure filter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-745154