Liquid purification or separation – With alarm – indicator – register – recorder – signal or...
Reexamination Certificate
1999-03-12
2001-02-13
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
With alarm, indicator, register, recorder, signal or...
C210S090000, C210S393000, C210S396000, C210S408000, C210S413000, C210S414000, C210S415000
Reexamination Certificate
active
06187177
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the filtering of fluids containing solid contaminants and, more particularly, to a high volume self-cleaning industrial pressure filter having a rotatable wiping member for cleansing the filter element of the filter.
2. Description of the Prior Art
Generally, filters have a wide variety of applications from waste water treatment to all types of industrial applications, such as petrochemical, food processing, and materials processing. Filters may be used whenever solid contaminants suspended in the unfiltered liquid may cause malfunction, damage, or must be removed for any other reason. In filters of this type, the fundamental problem is that when no suitable countermeasures are taken, the throughput of filtered liquid through the filter element is drastically reduced in that the filter element openings or apertures are continuously clogged on the inlet side of the filters by the solid contaminants contained in the unfiltered fluid. This problem is aggravated in pressure filters because the solid contaminants tend to be forced into and onto the filtering surface of the filter element and tend to cake over the filtering surface. To clean the filter element, the filter assembly generally requires extensive dismantling which results in a breakdown of operation and high maintenance costs.
Many methods and apparatuses have been used to attempt to self-clean the filter element in order to remove accumulated solid contaminants without the undesirable necessity of intermittent operational shutdowns of the filtering operation. For example, it is well know in the art to remove accumulated solids or sedimentation collected on the filter element during the filtering process by backwashing, in which a portion of the filtered liquid is caused to flow in a reverse direction through the filter element to clean the filter. More recently it has been recognized that the backwashing liquid may be supplied from an external source and at a pressure above the pressure of the fluid in the strainer. Exemplary of this is U.S. Pat. No. 3,074,560.
U.S. Pat. No. 3,357,566 shows a backwash filter having an inlet, a first outlet and a backwash outlet with a backwash arm having rubber edges defining a slot that engages the inside of the filter basket. The filter element is made of a plurality of vertically spaced rods. Similarly, U.S. Pat. No. 4,818,402 shows a backwashing filter having a fixed filter screen and a rotating backwashing apparatus for delivering high velocity liquid for backwashing the filter screen media.
It has also been known to provide a scraping shoe, which advances over the surface of a straining member and removes surface deposits of accumulated solid contaminants which are accumulated and immediately backwashed through a discharge. An example of such filters is shown in U.S. Pat. No. 2,275,958. Similarly, U.S. Pat. Nos. 5,198,111 and 5,569,383 disclose a cleaning unit that simultaneously moves both axially and rotatively along the interior of the filter element and carries a cleaning blade that moves in a conical helical path along the interior face of the filter element for removing accumulated solids.
While all of the above designs have useful applications, their designs are generally complex and typically have multiple seals that are prone to leakage and/or short seal life (which is especially aggravated when the unfiltered liquid is pressurized). Further, the filters heretofore designed and employed have been difficult to service due to the complexity of the design and the time required to separate the filter element from the cleaning components and to remove the cleaning components and the filter element from the housing of the filter.
SUMMARY OF THE INVENTION
Few improvements have been made in the reduction of the complexity of self-cleaning filters. The conventional methods and apparatus of prior art filters, or filter systems, for filtering solid contaminants suspended within unfiltered liquid are inadequate and require an inordinate amount of time and effort to separate the cleaning components and the filter element from each other and from the housing of the filter for routine maintenance and cleansing. This same complexity complicates the exchange of the filter element for one that has the appropriately sized filtering surface for the specific contaminated liquid to be filtered, which necessitates using the filter unit for one process type or application that will effectively work with the given porosity, or aperture size, of the specific filter element used or supplied by the manufacturer. The principal object of the present invention is to provide a pressure filter unit of the type described which is characterized by a compact design and a good aptitude for maintenance. Another objective of the present invention is to provide a pressure filter unit which has a high flow rate and good efficiency.
A further objective of the present invention is to provide a pressure filter unit having a filter element and wiper unit that can be easily removed from the filter housing for service or replacement. Yet another objective of the present invention is to provide a pressure filter unit having a filter element that has no mechanical seals between moving or movable components.
To achieve these and other advantages, and in accordance with the purpose of the invention, as embodied and broadly described, the present invention is directed to an industrial filter for filtering of fluids containing solid contaminants and, more particularly, to a high volume self-cleaning industrial pressure filter unit having a hollow housing having an unfiltered liquid inlet port and a filtered liquid outlet port. The housing contains a filter element of generally cylindrical shape which has a center longitudinal axis, an interior in fluid communication with the filtered liquid outlet port, and a porous sleeve having an exterior face in fluid communication with the unfiltered liquid for filtering suspended contaminant solids from the liquid. The sleeve of the filter element has a plurality of filter apertures in fluid communication with the interior of the filter element and the unfiltered fluid exterior to the filter element that are appropriately sized for the contaminant screening desired for the specified application. The housing may also have a contaminant outlet port in communication with the filtered contaminant solids for removal of filtered solids retained in the cavity of the housing. The filter unit may also have means for opening and closing the contaminant outlet port for removal of fluid carrying the accumulated filtered solid contaminants.
The filter unit also includes a wiping unit that overlies at least a portion of the exterior face of the sleeve of the filter element. The wiping unit has a wiper blade and a wiper unit longitudinal axis which is coincident and coaxial to the center longitudinal axis of the filter element. The filter unit further comprises means for rotating the wiping unit about the wiper unit longitudinal axis and the coaxial center longitudinal axis of the filter element so that the wiper blade is forced into scraping engagement with a portion of the exterior face of the sleeve for removal of filtered solid contaminants that may have accumulated on or caked onto the exterior face of the sleeve of the filter element. The filter unit may also have means for detecting the degree of contamination, or blockage, of the filtering apertures of the sleeve of the filter element.
The above and other objects and advantages of the present invention will become more readily apparent when reference is made to the following description taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 716989 (1902-12-01), Davidson
patent: 723639 (1903-03-01), Bliss
patent: 795047 (1905-07-01), Lynn
patent: 799395 (1905-09-01), Lynn
patent: 950118 (1910-02-01), Rood
patent: 2202191 (1940-05-01), Cuno
patent: 5595655 (1997-01-01), Steiner et al.
patent: 5632903 (1997-05-01), Caracciolo
Drodge Joseph W.
Needle & Rosenberg P.C.
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