Water filter abstract
Industrial water filter comprising a filter housing comprising
a sidewall and opposed endwalls, a radial inlet and an axial outlet.
A stationary filter is disposed operatively between the inlet and
outlet and generally eccentrically relative to the inlet axis so
as to produce a sweeping flow pattern along the screen. The interior
space between the screen and housing is divided diametrically along
an axial plane of the filter housing into two separate channels
each of which runs along the screen to a debris recovery zone diametrically
opposite the inlet. At the inlet end the interior space is divided
by a streamlined flow divider and at the debris recovery end by
a separator member which is either a flat plate or a streamlined
member. A stiffening web may be joined to the endwalls across an
axial plane of the screen. A partition may divide the interior space
perpendicularly to the outlet axis into two compartments.
Water filter claims
What is claimed is:
1. An industrial water filter of the type comprising a generally
cylindrical filter housing having a radial inlet and an axial outlet,
a stationary screen disposed in said filter housing operatively
between said inlet and outlet and generally eccentrically along
the axis of said inlet, an interior space being defined between
said stationary screen and said filter housing, means dividing,
into two separate channels, said interior space diametrically along
an axial plane of said filter housing containing said inlet axis,
each of said channels running along respective sides of said stationary
screen between said inlet and a debris recovery zone substantially
diametrically opposite said inlet, whereby a continuous sweeping
flow pattern is formed in each of the channels along said screen
preventing the build-up of debris and living matter entrained by
incoming water, said means dividing said interior space comprising
a flow divider comprising two vanes joined at their end adjacent
said inlet and spaced to respective sides of said axial plane at
their end adjacent said stationary screen, said vanes extending
the full height of said stationary screen for directing flow of
incoming water against and about said stationary screen, said ends
of said vanes being directly adjacent said stationary screen.
2. The filter of claim 1 wherein said means dividing said interior
space further comprises a separator member disposed along said axial
plane, remote from said inlet.
3. The filter of claim 2 wherein said filter housing comprises
a sidewall and two endwalls, said separator member extending from
one endwall to the other.
4. The filter of claim 2 wherein said separator member comprises
a simple plate.
5. An industrial water filter of the type comprising a generally
cylindrical filter housing having a radial inlet and an axial outlet,
a stationary screen disposed in said filter housing operatively
between said inlet and outlet and generally eccentrically along
the axis of said inlet, an interior space being defined between
said stationary screen and said filter housing, means dividing,
into two separate channels, said interior space diametrically along
an axial plane of said filter housing containing said inlet axis,
each of said channel running along respective sides of said stationary
screen betwen said inlet and a debris recovery zone substantially
diametrically opposite said inlet, whereby a continuous sweeping
flow pattern is formed in each of the channels along said screen
preventing the build-up of debris and living matter entrained by
incoming water, said means dividing said interior space comprising
a separator member disposed between said filter housing and said
stationary screen along said axial plane, remote from said inlet,
said separator member extending completely between said filter housing
and said stationary screen.
6. The filter of claim 5 wherein a web extends along said axial
plane from said flow divider to said separator member dividing the
interior of said stationary of said stationary screen in two.
7. An industrial water filter of the type comprising a generally
cylindrical filter housing having a radial inlet and an axial outlet,
a stationary screen disposed in said filter housing operatively
between said inlet and outlet and generally eccentrically along
the axis of said inlet, an interior space being defined between
said stationary screen and said filter housing, means dividing,
into two separate channels, said interior space diametrically along
an axial plane of said filter housing containing said inlet axis,
each of said channels running along respective sides of said stationary
screen between said inlet and debris recovery zone substantially
diametrically opposite said inlet, whereby a continuous sweeping
flow pattern is formed in each of the channels along said screen
preventing the build-up of debris and living matter entrained by
incoming water, said means dividing said interior space comprising
a flow divider comprising two vanes joined at their end adjacent
said inlet and spaced to respective sides of said axial plane at
their end adjacent said stationary screen, said means dividing said
interior space further comprising a separator member disposed along
said axial plane, remote from said inlet, said separator member
comprising a streamlined vaned member including two vanes which
are joined at their end remote from said inlet and spaced from each
other on opposite sides of said axial plane at their end closer
to said inlet.
Water filter description
BACKGROUND OF THE INVENTION
The present invention relates generally to filters commonly used
for filtering water for industrial use, and in particular water
for cooling plants and equipment such as steam turbine condensers.
Such filters are designed to retain both debris and living matter
such as shellfish and algae which are capable of proliferating downstream
in the associated equipment to the detriment of its operation should
the living matter not be eliminated beforehand.
The present invention relates more particularly to such filters
which comprise a generally cylindrical housing having a radial inlet
and an axial outlet, a stationary screen or strainer disposed in
the filter housing and operatively interposed between the inlet
and the outlet.
The term "radial inlet" is intended to mean an inlet
connected to the sidewall of the filter housing and substantially
perpendicular to the axis of the filter housing and the term "axial
outlet" is intended to mean an outlet connected to one of the
endwalls of the filter housing extending along the axis of the housing
or at least parallel to the axis of the housing.
One of the problems posed in the design of filters of this type
is how to avoid the clogging of the screen or strainer.
DISCUSSION OF THE PRIOR ART
German patent publication No. 2225726 discloses a filter in which
a butterfly valve is disposed in the inlet, and for facilitating
the location of the butterfly valve it is suggested that the stationary
screen in the housing should be eccentric relative to the axis of
the inlet. By changing the position of the butterfly valve in the
inlet, it is at least theoretically possible to clean the screen
when debris tends to build up thereon. But turbulent flow is caused
in the corresponding fluid screen which translates into momentary
disruption in the flow rate and a not insubstantial disturbance
downstream. Further, the cleaning of the screen is effected at will,
when the screen is already partially clogged or in the process of
becoming clogged.
In my U.S. Pat. No. 4276171 there is disclosed a filter which,
on the contrary, continuously avoids the build-up of debris and
clogging on the filter screen.
This filter is characterized by the combination of the orientation
of the inlet and the spiral configuration of the sidewall of the
filter housing or, more generally, a gradually decreasing flow pattern
from the inlet to the debris recovery zone between the sidewall
of the filter housing and the stationary screen. A continuous sweeping
or cleaning of the stationary screen is thus insured by the incoming
stream whereby the debris or living matter entrained by the incoming
stream is prevented from accumulating on the screen. The debris
or living matter entrained by the incoming stream is carried to
the recovery zone from where it is periodically discharged.
Although this filter has been found to be satisfactory, owing to
its efficiency and simple construction, as well as its ability to
permanently maintain the nominal flow rate without disruption by
any moving components and without a drop in its flow rate, it does
have drawbacks due to its asymmetrical configuration. Indeed, it
has been found that it is necessary to externally reinforce the
filter housing along the spiral sidewall and the endwalls. The ultimate
cost of the filter is increased accordingly.
SUMMARY OF THE INVENTION
A general object of the invention is the provision of a filter
which avoids this drawback while preserving the advantages of continuous
sweeping flow along the screen, while producing other advantages.
According to the invention there is provided an industrial water
filter comprising a generally cylindrical filter housing a radial
inlet and an axial outlet, a stationary screen disposed in the filter
housing operatively between the inlet and outlet and generally eccentrically
relative to the axis of the inlet. An interior space is defined
between the stationary screen and the filter housing. Means divides
the interior space into two separate channels along an axial plane
of the filter housing containing the inlet axis. The channels run
along the respective sides of the stationary screen between the
inlet and a debris recovery zone substantially diametrically opposite
the inlet, whereby a continuous sweeping flow pattern is produced
along the stationary screen preventing the build-up of debris and
living matter entrained by incoming water.
Accordingly, the filter operates as if it was made of two substantially
semicylindrical half filters adjoining each other along a common
diametrical plane.
The present invention is based on the rather surprising observation
at first glance that for the sought after continuous sweeping flow
pattern along the screen to avoid clogging it was not necessary
for the flow pattern to sweep along substantially 360.degree. but,
on the contrary, it was possible to obtain satisfactory operation
with a sweeping flow pattern restricted to less than 180.degree..
In fact, since the inlet is radial the incoming stream is divided
into two substantially equal branch streams, each flowing along
one side, and the branch streams flow around the stationary screen.
The branch streams gradually narrow along the stationary screen
thereby insuring a uniform velocity distribution and, therefore,
a uniform flow along each half of the screen. The branch streams
also sweep along the surface of the screen thereby, with undiminished
efficiency, preventing the build-up of entrained debris or living
matter, which is carried to the associated debris recovery zone.
The construction of the filter housing, which is thus advantageously
symmetrical, is simplified. When the sidewall of the filter body
is to be of spiral configuration, and taking into account the fact
that the sidewall for each half filters covers less than 180.degree.,
it is advantageously possible to roughly approximate this by an
appropriate eccentricity of the stationary screen in the filter
housing. The portion of the sidewall of the corresponding half filter
may simply be of semicylindrical configuration comprising a single
circular arc, whereas when the contour is a spiral, covering 360.degree.,
it is normally necessary to approximate the same by providing three
successive circular arcs of different radii.
Of course, if desired, to improve the approximation of the sought-after
spiral contour, each of the sidewall portions of the filter housing
corresponding to a half filter may comprise at least two successive
circular arcs or even a true spiral.
In actual practice, according to the preferred embodiment, the
division of the interior space into two separate chambers is provided
on the inlet side by a two-vaned streamlined flow divider, the vanes
being joined adjacent the inlet and spaced from each other adjacent
the screen, each vane being disposed to one side of the axial plane
containing the axis of the inlet extending through the filter housing
thereby producing a tangential incoming stream. At the opposite
or the debris recovery zone side the chambers are divided by a separator
member disposed along the said axial plane and comprising a simple
plate or a streamlined vaned member like the streamlined flow divider
used at the inlet side.
The flow divider and the separator member are, according to a feature
of the invention, connected to each other by a diametral partition
in the stationary screen, advantageously extending from one endwall
to the other. They advantageously comprise reinforcement members
for the endwalls so as to eliminate the need for any external reinforcements.
Similarly, if desired, the interior space of the filter housing
between the stationary screen and the filter housing may be divided
through the axis of the filter housing into at least two separate
compartments by an internal partition perpendicular to the axis
thereby internally reinforcing the sidewall of the filter housing
and contributing to the obtention of a homogeneous distribution
for the incoming stream which facilitates the treatment of the incoming
stream and the discharge of the debris or living matter from the
filter.
Consequently, taking into account the shortness of the flow path
in the filter of the invention, which extends along substantially
180.degree., the efficiency of the periodic discharge of the debris
or living matter accumulated in the debris recovery zone is improved.
Finally, since the inlet is radial, the outer dimensions or overall
volume of the filter is advantageously reduced, namely as regards
the distance between the axis of the stationary screen and the plane
of the coupling flange usually provided on the free end of the inlet.
These and other features of the invention will be brought out in
the description which follows, by way of example, with reference
to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a longitudinal sectional view of a filter embodying
the invention, taken along line I--I in FIG. 2; and
FIG. 2 shows a cross-sectional view taken along line II--II in
FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in the drawings and known per se, the present industrial
water filter comprises a generally cylindrical housing 10 having
an inlet 11 and an outlet 12 and a stationary screen or strainer
13 which is disposed inside the filter housing 10 and operatively
interposed between the inlet 11 and the outlet 12. The filter housing
10 comprises a cylindrical sidewall 14 and two endwalls 16 17 disposed
transversely to the axial ends of the sidewalls 14.
In the drawings, the contour of the cylindrical sidewall 14 of
the filter housing 10 is of circular section to simplify the representation.
In FIG. 2 the axis of the cylindrical sidewall 14 is marked by
a phantom cross A1.
The inlet 11 is radial, in other words it is connected to the sidewall
14 of the filter housing 10 and its axis A2 marked by a phantom
cross A2 is perpendicular to axis A1 of the sidewall 14. At the
free end of the inlet 11 is a radial coupling flange 18. Preferably,
the inlet 11 is of rectangular cross section in its connecting zone
with the sidewall 14. The inlet has a circular or polygonal section
in line with the coupling flange 18. As is known per se, the inlet
11 is shaped to permit connection between sections of different
contours.
The outlet 12 extends from an opening 19 of circular contour in
endwall 17 of the filter housing and is axial, i.e., its axis A3
marked by a phantom cross in FIG. 2 is parallel to axis A1 of the
sidewall 14 of the filter housing 10.
Like inlet 11 outlet 12 is provided at its free end with a radial
coupling flange 20.
Stationary screen 13 is disposed inside filter housing 10 and extends
axially from one endwall 16 to the other 17 and outlet 12 is the
continuation of the stationary screen 13. The axis of the stationary
screen 13 coincides with axis A3 of the outlet 12. In practice,
as illustrated, the stationary screen 13 is generally eccentric
inside the filter housing 10. The axis A3 of the stationary screen
13 is located farther from the inlet 11 than the axis A1 of the
cylindrical sidewall 14 of the filter housing 10.
According to the invention the interior space of the filter, between
the stationary screen 13 and the filter housing 10 is diametrically
divided into two separate chambers A, B, along the diametral plane
P of the housing 10 containing the axis A2 of the inlet. The diametral
plane P is schematically shown by a phantom line in FIG. 2 and coincides
with that of the axis A2 of the inlet 11. The channels A, B are
disposed on the respective sides of the stationary screen 13 and
extended from the inlet 11 to the associated debris recovery zone
22A, 22B diametrically opposite the inlet 11.
In the illustrated embodiment the debris recovery zones 22A, 22B
protrude from the sidewall 14 of the filter housing 10 extend along
the entire height of the sidewall 14 and have an overall trapezoidal
cross-sectional configuration.
In practice, at the inlet end the interior space of the filter
is divided into the two channels A, B by a streamlined flow divider
23 comprising two vanes 24A, 24B which are joined at their end adjacent
the inlet, preferably tangent to each other as shown, and are spaced
apart at the other end, adjacent the stationary screen 13 to respective
sides of the axial plane P.
In the illustrated embodiment, on the screen side the vanes 24A,
24B of the flow divider 23 are joined to each other by a panel 24
contiguous with the adjacent portion of the screen 13 whereby the
cross-section of the flow divider 23 is generally a curvilinear
triangle. The junction zone of the inlet 11 with the sidewall 14
of the filter housing 10 has a configuration complementary to that
of the vanes 24A, 24B.
The division of the interior space into two separate channels A,
B at the side remote from the inlet is effected by a separator member
lying along the axial plane of the filter housing 10. In the illustrated
embodiment, as shown in solid lines in FIG. 2 the separator member
is a mere plate member 25 which extends diametrically to the end
of the debris recovery zones 22A, 22B.
Preferably, a stiffening web 27 extends diametrically across the
stationary filter 13 from the flow divided 23 to the separator member
25.
In any event, the flow divider 23 and the separator member 25 extend
axially from one endwall 16 to the other 17 of the filter housing
10.
Moreover, in the illustrated embodiment the interior space of the
filter between the stationary screen 13 and the filter housing 10
is divided into two compartments C1 C2 by an interior partition
28 extending perpendicularly to axis A1 of the filter housing 10.
In each compartment C1 C2 a discharge conduit 30.sub.1 30.sub.2
controlled by a valve 31.sub.1 31.sub.2 is provided for each of
the debris recovery zones 22A, 22B discharging the accumulated debris
or living matter.
A frustoconical deflector 33 is disposed axially inside the stationary
screen 13 the frustoconical deflector 33 tapering toward the outlet
12. At its end opposite the outlet 12 the frustoconical deflector
33 has a cross section less than that of the stationary screen 13.
The constructional expedients of the filter thus constructed and
schematically illustrated in the drawings are a matter for those
skilled in the art and need not be described in detail herein. The
actual construction is in any event simplified by the symmetrical
configuration of the filter.
As illustrated by arrows F.sub.A, F.sub.B in FIG. 2 the incoming
stream is divided into two equal half streams on the respective
sides of the axial plane of the filter. Each of the half streams
sweeps along the corresponding semicylindrical surface of the stationary
screen and through the perforation therein so that the various debris
and living matter entrained is prevented from building up on the
stationary screen and accumulates in the corresponding debris recovery
zones 22A, 22B which are periodically evacuted by means of the discharge
conduits 30.sub.1 30.sub.2.
It will be understood that the present invention is not intended
to be limited to the illustrated and described embodiment by encompasses
all modifications and alternatives understood to those skilled in
the art without departing from the spirit and scope of the appended
claims.
For example the debris recovery zones may form a single debris
recovery zone. Also, the number of interior partitions is unimportant;
the shape of the deflector 33 and the configuration of the flow
divider are subject to various modifications.
Further, as shown in phantom lines in FIG. 2 the separator member
on the side opposite inlet 11 may comprise a streamlined vaned member
25' such as the flow divider 23 comprising two vanes which are
joined at their end remote from the inlet and spaced apart at their
end closer to the inlet, to the respective sides of the axial plane
of the filter housing including the axis of the inlet.
Generally speaking, the arrangement of the overall filter into
two parts symmetrical with respect to a plane, which is advantageously
defined by the stiffening web 27 considerably facilitates the construction,
especially for large size units.
Furthermore, and it will be understood, the present filter is advantageously
entirely static, with no moving parts necessary for effecting the
unclogging of the structure. Clogging is prevented in operation
by the sweeping flow pattern with the threefold advantages brought
out in my U.S. Pat. No. 4276171 and discussed hereinabove. |