Liquid purification or separation – With repair or assembling means
Reexamination Certificate
1999-10-13
2002-03-26
Savage, Matthew O. (Department: 1723)
Liquid purification or separation
With repair or assembling means
C210S315000, C210S338000, C210S342000, C210S452000, C210S455000, C210S477000, C210S497010, C210S498000
Reexamination Certificate
active
06361690
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, generally, to filters for removing particulate matter from fluid and, more specifically, to bag filters of the type which are supported by a permeable basket which, in turn, is usually positioned in a housing or vessel through which the fluid to be filtered is passed.
2. Background of the Invention
A conventional filter assembly of the type having a basket which supports a bag filter and generally known in the related art is shown at
10
in FIG.
1
. The conventional assembly
10
includes a vessel
12
having an inlet
14
, an outlet
16
and a substantially cylindrical filter chamber
18
defined therebetween. A cover
20
is removably mounted to the otherwise open top
22
of the vessel
12
. A permeable, filter basket
24
is received in the chamber
18
through the top
22
of the vessel
12
and may be supported by a peripheral flange
26
extending radially inward from the inner side wall of the chamber
18
. The basket
24
has a diameter which is less than the diameter of the chamber
18
and, together, they define an annular flow passage
28
therebetween. A cylindrical bag-like filter element
30
is supported by the basket
24
in the filter chamber
18
. The filter element
30
may be manufactured from needled felt, meshes or any other material which provides a mechanical straining effect on the fluid.
In operation, dirty fluid shown shaded in
FIG. 1
enters the chamber
18
through the inlet
14
of the vessel
12
as indicated by arrows A and flows into the filter element
30
(as indicate by arrows B) which is supported by the permeable basket
24
. The fluid passes through the bag-type filter element
30
, as indicated by the arrows C, and is thereby cleaned. Clean fluid exits the chamber through the outlet
16
, as indicated by the arrows D. During this filtering process, the basket
24
does not fill up with particulate. Rather, the bag-like filter element
30
becomes coated with the particulate and other unwanted matter. The bag filter
30
must be replaced at specific intervals which can vary depending upon the application and the purification of the fluid that is required. An increase in the back pressure through the vessel
12
is often used as an indicator that the filter must be changed.
Filter assemblies of this type are often employed in industrial environments to filter water, oil, water soluble oil, paint as well as consumable fluids such as soft drinks and liquor. Another example of a conventional filter assembly of this type is shown in U.S. Pat. No. 4,701,259 issued to Rosaen on Oct. 20, 1987.
Ultimately, the useful life of the bag-type filter elements is determined by the surface area of the filter. The larger the surface area, generally speaking, the longer the useful life of the filter. While relatively inexpensive to replace, bag-type filter systems in the past have suffered from the disadvantage that, in certain applications, the filter elements must be replaced often—sometimes more than once a production shift.
In recognition of this deficiency, it has been proposed to arrange two filters in series in a given vessel or chamber. However, this proposed solution does not result in twice the useful life of the filter element. Furthermore, the pressure drop across a vessel having two filters in series is approximately twice that of a system employing a single filter element.
It has also been proposed to employ a pleated filter element in this environment. Pleated filter elements provide a much higher filter surface area when compared with bag-type filter elements. This results in a longer useful life of the filter element. However, pleated filter elements of the related art suffer from the disadvantage that they are many times more expensive than the bag-type filter elements. Accordingly, in many manufacturing environments where reducing operational costs is paramount, pleated filter elements have not been adopted.
Thus, there remains a need in the art for a basket filter assembly which employs an inexpensive bag-type filter element with good filtering properties, low pressure drop and having a relatively long useful life.
SUMMARY OF THE INVENTION
The present invention overcomes the disadvantages in the related art in a filter assembly including a filter vessel having an inlet and an outlet and defining a filter chamber therebetween. A basket assembly is removably supported within the filter chamber. The basket assembly has a diameter less than the diameter of the filter chamber so as to define an annular flow passage about the basket assembly. The basket assembly includes an outer permeable member and an inner permeable member having a diameter which is less than the diameter of the outer permeable member such that the inner permeable member is received within the outer permeable member so as to define an annular space therebetween and inner flow path. The basket assembly is capable of supporting a bag type filter over both the inner and outer permeable members bounding the annular space therebetween. To that end, the bag type filter includes a first portion having a first, larger diameter and a second portion having a second, reduced diameter. In addition, the bag type filter has a transition portion disposed between the first and second portions. The bag type filter is specifically adapted to be received on the basket assembly and be supported by the outer and inner permeable members in the annular space therebetween.
Accordingly, the filter assembly of the present invention provides a filter surface area which is much larger than conventional filter assemblies known in the related art. Thus, the present invention may be used to double the useful life of the bag-type filter without any substantial increase in cost or to double the flow rate through the vessel for the same useful life of a conventional filter and, while at the same time in either case, reducing the pressure drop of the fluid through the vessel. Alternatively, the present invention facilitates a reduction in size of the vessel while maintaining the same respective useful life of the filter. Smaller vessels reduce the plant space required for these filtering systems. Finally, the bag-type filter of the present invention is inexpensive, cost efficient and is easy to use in the field.
REFERENCES:
patent: 2545769 (1951-03-01), De Haven
patent: 2580209 (1951-12-01), Wiley
patent: 2763373 (1956-09-01), Pearce
patent: 4081379 (1978-03-01), Smith
patent: 4193780 (1980-03-01), Cotton, Jr. et al.
patent: 4447326 (1984-05-01), Riede et al.
patent: 4496459 (1985-01-01), Rosaen
patent: 4498989 (1985-02-01), Miyakawa et al.
patent: 4536228 (1985-08-01), Treharne
patent: 4642089 (1987-02-01), Zupkas et al.
patent: 4701259 (1987-10-01), Rosaen
patent: 5645721 (1997-07-01), Carroll, Jr.
patent: 5782791 (1998-07-01), Peterson et al.
patent: 5910247 (1999-06-01), Outterside
Bliss McGlynn & Nolan, PC
Savage Matthew O.
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