Liquid purification or separation – Processes – Separating
Patent
1990-01-24
1991-10-15
Dawson, Robert A.
Liquid purification or separation
Processes
Separating
210340, 210345, 210499, 55525, B01D 2933, B01D 2952
Patent
active
050572326
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention is directed to a filter element for use in a container with a central pipe which is closed along its length and provided with a lower opening, as well as to a method of filtration.
A filter element comprising a central pipe for draining off a filtrate, which central pipe is closed along its entire length and is only open at the top and bottom, is known from CH-A-631 352. The known filter element is suitable for a filtration for separating fine particles from a suspension and for a residual volume filtration, but does not satisfy the imposed requirements under extreme conditions in which filtration which is free of foreign matter is required. In this case, foreign matter is understood to mean the finest particles which can be disengaged, e.g., from multiple-filament woven textile filters and which must be removed, e.g. in the production of serum.
Filter cartridges which are woven from monofilament, particularly metal wire, are known per se. However, they have the disadvantage that dynamic cleaning is not possible with them, and an attached filter cake can therefore be removed only with great difficulty and incompletely. The woven wire fabrics are rigid and are permeable to air to a relatively great degree. In order to detach a dry filter cake and subsequently discharge it from a filter container, greater quantities of gas in sudden bursts are required than is the case when using textile filter.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a filter element, which has the characteristics of rigid monofilament filter means, but nevertheless allows a simple and complete removal of a filter cake.
Another object of the invention is a method of filtration with such a filter element.
The object is met, by a structure in which the central pipe is concentrically enclosed by a cylinder whose bottom part can be closed.
The central pipe has a relatively small cross-section compared to the cylinder surrounding it. The two pipes are arranged coaxially. This arrangement enables a separate path for the filtrate and a separate path for the gas used to remove the filter cake. This has the advantage that a much greater quantity of gas can be made available for brief periods than is possible by a known back-flushing via the filtrate line.
According to a preferred construction, the cylinder for the air feed projects out over the length of the central pipe and forms a more or less semicircular base or space in its lower part. But the base can also be flat.
For constructions which can be sterilized, an additional filter means is provided at the lowest point of the base for the condensate run-off. This additional filter means may be a plate of filter material.
The filter plate advisably comprises the same filter means as are used for filtration, particularly a sintered metal which is welded into the base.
The cylinder enclosing the central pipe communicates via pipes with the interior of the filter means, which preferably consist of tubular filter elements of woven wire. The object of the pipes is to guide off the filtrate in an unimpeded manner during the filtration and to let through large quantities of air in short periods of time during the removal of a filter cake. These pipes can also be arranged one above the other and can connect filter means with the cylinder, which filter means enclose the central pipe.
It is advisable to arrange the collecting pipe above the compressed gas distributor pipe for draining off the filtrate.
Metal woven fabrics have proven advantageous as filter means for filtration which is free of foreign matter. However, chemically and thermally resistant monofilament of plastic can also be used instead of the metal woven fabrics. Sintered-metal or sintered-ceramic cartridges can also be used.
The invention both as to its construction so to its mode of operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of the preferred embodiments with reference to
REFERENCES:
patent: 2606628 (1952-08-01), Hasselwander
patent: 2886180 (1959-05-01), Morgan et al.
patent: 3023905 (1962-03-01), McDougal et al.
patent: 3536200 (1970-10-01), Gigliatti et al.
patent: 4544483 (1985-10-01), Aruai
patent: 4814078 (1989-03-01), Stern et al.
Muller Patrick A.
Schumacher Ivo
Stahl Werner
Stocker Walter
Dawson Robert A.
DrM, Dr.Muller AG
Millard Wanda L.
Striker Michael J.
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