Rotating fluid seal

Details Rotating fluid seal Rotating fluid seal

2000-11-10

2003-12-16

Gall, Lloyd A. (Department: 3676)

Seal for a joint or juncture

Seal between relatively movable parts

Circumferential contact seal for other than piston

C277S345000, C277S553000, C277S555000, C277S903000

Reexamination Certificate

active

06663109

ABSTRACT:

TECHNICAL FIELD
The present invention relates to systems for providing a fluid a seal between a rotating and a stationary portion of a fluid container.
BACKGROUND OF THE INVENTION
Circular clarifier systems and other large diameter process equipment are important in water treatment, wastewater treatment and mining. In some existing circular clarifier systems, a rotating sludge removal mechanism typically includes a series of pipes which rapidly remove sludge from the bottom of the clarifier. In such sludge removal systems, sludge removal pipes are used to draw the sludge up from the bottom of the clarifier tank and then discharge the sludge to a circular chamber, referred to as a “launder”, which typically includes both a rotating portion and a stationary portion. The rotating portion is typically connected to the sludge removal pipes which rotate around the bottom of the clarifier, and the stationary portion is typically connected to a discharge pipe from which the sludge is pumped away from the clarifier for disposal or further processing. Essentially, such a “launder” typically resembles an annular shaped fluid drum.
An example of such an existing sludge removal system is seen in U.S. Pat. No. 3,951,819 to Shaffer et al., entitled Sludge Removal System.
FIG. 1
is a simplified sectional side elevation view of such a system, and
FIG. 2
is a simplified top plan view of such a system. As can be seen in
FIGS. 1 and 2
, system
10
comprises a launder
12
having an outer rotating portion
12
A and a central stationary portion
12
B. As can also be seen, water level L
1
(outside of launder
12
) is higher than water level L
2
(inside of launder
12
). This differential water level (i.e.: L
1
-L
2
) provides the force to cause the sludge to flow from the bottom of the clarifier up through conduits
14
, and into launder
12
. Specifically, water pressure is created by L
1
being higher than L
2
such that fluid flows upwardly through conduits
14
(entering at end
13
and exiting into launder
12
through end
15
). As such, sludge which has settled to the bottom of clarifier
10
is essentially siphoned from the bottom of the clarifier tank, and is then removed from the clarifier through discharge conduit
18
. As portion
12
A of the launder rotates in direction R, conduits
14
also rotate in direction R, thereby siphoning sludge from the bottom of the clarifier in a circular fashion. (In a typical clarifier system, a plurality of conduits
14
, each having their ends
13
disposed at different radial distances from the center of the clarifier, are used to siphon sludge across the entire bottom surface of the clarifier).
As can be appreciated, a problem with this existing clarifier systems is the problem of providing an effective fluid seal between outer rotating portion
12
A and a central stationary portion
12
B of launder
12
. Specifically, existing clarifier launder seals have tended to suffer from numerous deficiencies, including poor sealing efficiency and rapid wear and tear of the sealing surfaces, due to the fact that center portion
12
A of the clarifier launder remains stationary as the outer portion
12
B rotates therearound. As it is necessary that water level L
2
in launder
12
be kept lower than water level L
1
in the rest of clarifier
10
, it is necessary to maintain an effective seal between the stationary portion
12
B and the rotating portion
12
A of launder
12
.
FIG. 3
shows a sectional elevation view of a typical existing sealing system
20
adapted for use between rotating portion
12
A and stationary portion
12
B of launder
12
. System
20
comprises a flat horizontal flexible strip
22
which may by annular (or circular) in shape such that it extends across and seals gap
33
. Typically flexible strip
22
is made of an elastomer (for example, rubber) which is bent at its outer perimeter by about 90 degrees between inner end
21
and outer perimeter
23
. Flexible strip
22
will tend to bounce back or straighten itself such that end
23
pushes against edge
24
of rotating portion
12
B of launder
12
. As such, flexible strip
22
will thus provide a seal between rotating portion
12
B and stationary portion
12
A of launder
12
. As can be seen, a circular hose
26
can be held in position by a plurality of hose clips
28
to provide further support to flexible strip
22
.
Flexible strip
22
deflects to accommodate limited relative lateral motion in direction L between the rotating
12
B and fixed
12
A portions of launder
12
. Unfortunately, the amount of such lateral motion in direction L that can be accommodated is quite limited (typically to fraction of an inch, even for a large diameter seal). Moreover, the rubber portion of the seal (i.e.: flexible strip
22
) tends to deteriorate over time and eventually fail. Deterioration of this seal reduces the motive force for sludge withdrawal and dilutes the sludge, reducing the overall clarifier performance.
SUMMARY OF THE INVENTION
The present invention provides a fluid seal assembly, which in preferred aspects prevents movement of fluid through an annular gap between an inner edge of a circular hole passing through a first member and a second member having a circular outer perimeter.
As such, the present system is ideally suited for use in wastewater treatment clarifier launders. Specifically, in preferred aspects, the present invention provides a seal which substantially restricts or prevents fluid movement through an annular gap between the rotating and stationary portions of a wastewater clarifier launder. However, the application of the present invention is not so limited. Rather, the present invention can be used to provide a fluid seal across an annular gap between any two members, including any system wherein the first and second members are rotatably positionable with respect to one another.
In various aspects, the present invention can be used to provide a seal across an annular gap between a first and a second member wherein the first member is rotated while the second member remains stationary; or wherein the second member is rotated while the first member remains stationary; or wherein the first and second members are rotated, but at different speeds or in different directions.
In a first aspect of the invention, a first contacting member is positioned to span across the gap, with the first contacting member being attached to either one or the other of the first and second members. A plurality of support assemblies are attached to the same member to which the contacting member is attached. These support assemblies are specifically adapted to bias the first contacting member into contact against the other member to which the contacting member is not attached.
Various modifications are possible. For example, the first contacting member and the various support assemblies may together be attached to the member disposed on either the inner or the outer edges of the gap (i.e.: attached to either the first or second members).
In preferred aspects, the various support assemblies comprise a biasing mechanism, a pivot member and a sealing support assembly. The sealing support assembly pivots about the pivot member with the biasing mechanism urging the sealing support assembly against the first contacting member. This is turn either urges the first contacting member directly against the member to which the first contacting member is not attached, or alternatively, the first contacting member is urged directly against a second contacting member (which is positioned between the first contacting member and the member to which the first contacting member is not attached).
Preferably, the first contacting member, and the optional second contacting member are made of a suitably tough but flexible low friction material, which may optionally include ultra-high molecular weight polyethylene. When a second contacting member is not used, the member to which the first contacting member is not attached (i.e.: the member which the first contacting member is instead biased against) is prefera

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