Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to oil-water separation
apparatus. More particularly, this invention relates to an
improved, cartridge-type filtering apparat~ls contalning a
block of squeezable foam that is encased in an envelope of
flexible, impervious material to avoid channeling and provide
a more efflcient and effective oil-water separation process.
In U. S. Patent No. 3,617,551 to Johnston, there is
generally disclosed oil-water separation apparatus having a
flow-through chamber containing a block of regenerable,
porous filter material, such as polyurethane foam. The
block of material is located between a pair of spaced,
perforated plates and at least one of the plates is movable
in response to an applied pressure to periodically squeeze
absorbedoil from the filter material and regenerate it for
further use.
To minimize the tendency to channel or short-circuit
the feed water along the walls of the chamber, the foam
block is oversized with respect to the chamber to produce
precompression of the foam against the inside walls of the
chamber. The oversizing of the foam, however, necessarily
creates friction between the foam and the stationary walls
of the chamber during regeneration, preventing it from
recovering its initial shape following regeneration. Mini-
mization of the channeling, therefore, is limited by the
elastic capacity of the foam to overcome this friction
generated by the lateral precompression. Moreover, the
shape of the foam resulting from its incomplete recovery
because of wall friction results in a deterioration of its
filtration characteristics and may affect its integrity
after repeated squeezing.
Accordingly, it is an object of the present invention
to provide a cartridge-type, filtering apparatus that success-
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fully avoids channeling in the flow o~ -feed water through
the apparatus but that perlnits the foam block to readily
compress and expand within the chamber during regeneration
without interfeTing with the side walls of the chamber.
In accordance with the present invention, SUC]l objectives
are achieved in oil-water separation apparatus having a flow-
through separation chamber containing a block of porous
material regenerable by compression and a pair of perforated
plates located on either side of the block at least one of
whicll responds to applied pressure to compress the material,
by providing an envelope of flexible, impervious material
completely surrounding the outer surface of the foam block
between the block and the inside walls of the chamber. The
envelope is connected at either end to the plates and prefer-
ably in a releasable manner so that the foam material and
envelope can be readily replaced when necessary.
It is to be understood that both the foregoing general
description and the following detailed description are
exemplary and explanatory but are not restrictive of the
inventicn.
The accompanying drawings constitute a part of the
speci~ication and illustrate a p-feferred embodiment of the
invention and together with the description serve to explain
the principles of the invention.
Of the drawings:
FIG. 1 is a schematic, cross-sectional view of a
cartridge-type oil-water separation apparatus embodying the
improvement of the prqsent invention;
1 ~7. ~ is an cxploded, fragmentary view showing a clamp^
in~ of the flexible envelope to the perforated plates; and
l:IG. 3 is a fragmentary view similar to FIG. 1, but
s}lowing tne foam block during regencration.
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With reference to FIG. 1, the oil-water separation
appara-tus includes a housing 10 having an oil-contaminated
water inlet 12 and outlets 14 and 16 for the separated oil
and water, respectively. ~lousing 10 is divided into three
interconnected chambers, preferably arranged horizontally as
shown in the drawings. These chambers consist of a separation
chamber 20 essentially in the middle of the housing, a feed
chamber 22 communicating with the influent side of separation
chamber 20 for distributing the flow of feed uniformly
through that chamber, and a floatation chamber 24 on the
effluent side of the separation chamber for receiving the
effluent from the separation chamber and permitting gravity
separation of the effluent.
Separation chamber 20 is filled with a cartridge or
block of porous material 26, having filtering characteristics
Wit]l respect to the contaminated feed and, more particularly,
oil-absorbing and oil-coalescing characteristics, that is
regenerable by compression to remove absorbed contaminant
from the material. Block 26 is held in position in housing
10 between two perforated plates 28 and 30; the rear perforated
plate 28 being fixed in the housillg ancl the front plate 30
being mounted for axial movement in response to applied
pressure with respect to fixed plate 28. As shown, the
means for applying pressure to plate 30 to compress porous
block 26 and regenerate it for furthe:r use comprises a
hydraulic cylinder 32 mounted on the front wall 3~ of housing
10 and having a piston 36 that extends through feed chamber
22 and is connected to movable perforated plate 30. Thus,
it can be seen that, as hydraulic cylinder 32 is actuated,
perforated plate 30 pushes towards fixed rear plate 2~
compressing material block 26 and expelling absorbed contamin-
ant out of thc block and into chambers 22 and 24.
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Alternatively, if it is desired to express the absorbed
contaminant during compression in only one direction, for
example, only into floatation chamber 24, suitable one-way
valves would be incorporated in plate 30 that would be open
during the flow of feed through the system, but that would
close during compression and regeneration.
Feed chamber 22 of housing 10 is defined by the space
between the inside of front wall 34 and the front face of
perforated plate 30 in its retracted position. ~Vhile the
provision of a feed chamber is not essential, it is desirable
to permit the feed to be uniformly distributed over perforated
plate 30 for uniform flow through porous block 26.
In accordance with the present invention, a flexible
envelope 40 of impervious material completely surrounds the
outer surface of foam block 26 and is located between the
block and the inner wall surface 42 of separation chamber
20. Envelope 40 is of less diameter than wall surface 42
and is connected at either end to perforated plates 28 and
30, thus essentially providing a cartridge of filter material
between the end plates that is separated from the inner
wall of the housing.
The selection of the material comprising porous block
26 is not critical provided the material has an open,
reticulated structure and when used as an oil-water separator
desirably have both oil-absorbing and oil-coalescing proper~ies.
A material found to be ideally suited for such use is a block
of polyurethane foam having a pore size of between 30 and
100 pores per linear inch (ppi) and preferably a pore size
of around 60 ppi. As more f--lly described below in connection
with the operation of ths system, it has been found that such
polyurethane foams demonstrate excellent oil-scavenging
propertics wit?l good flow characteristics over a large range
of oil properties ~nd concentrations.
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Material 26 may consist of a pluraliky of discrete
chips OT a plurality of se-gmented pads lined up in series
within the envelope, but preferably is a single, integral
block of the porous foam. The block, in general, is found
to be more eficient than filling up the envelope with a
plurality of small chips of a compressible material.
Envelope 40 is preferably a sheet of impervious fabric
having a rubberized coating, such as a hy~alon coated sheet
of a polyester fabric.
In accordance with the invention, clamping means are
provided for releasably clamping the ends of the envelope to
the plates so that the envelope and foam block can be removed
and replaced when necessary. As embodied and as best shown
in FIG. 2, this means comprises an annular bracket 44 located
on the inner surfaces of each plate that forms a channel 46
opening outwardly with respect to separation chamber 20.
The ends of envelope 40 are draped into channels 46 and then
clamped in place by a cable 48. The ends of cables 48 can
be simply crimped together and then cut apart when it is
necessary to replace the envelope or preferably they can be
provided with a quick releasable clamp so they can be reused
following replacement of the envelope. In any event, the
clamping means should be tight enough to provide a sealed
connection between the envelope and the plate and in
particular between the envelope and the downstream plate.
Preferably, housing 10 and foam block 26 are circular
and the block is oversized with respect to envelope 40 to
precompress the foam against the envelope and avoid channeling
between the envelope and the foam and the envelope is of
less diameter than the chamber to prevent the envelope from
contacting with the walls of the separation cllamber.
Preferably, floatation chamber 24 is contiguous with
separation chamber 20, forming an integral part of housing
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10 and detined by the section between fixed rear perEorated
plate 2g and the rear w~ll of the hous;ng. This provides a
more COJIlpaCt and efficient separator, but it will readily be
apparent to those skilled in the art that chamber 2~ could
be remote from the housing with suitable piping to transfer
the effluent to the chamber.
Chamber 24 is preferably divided into two parts, as
more clearly sho~n in Fig. 1, by a baffle 39 to avoid
contamination of the clean water outlet 16 and to increase
gravity separation by creating an upward flow of the ef-fluent
in the chamber. When the oil is a light oil, the coalesced
droplets accumulate at the top of chamber 24 and the upward
flow of effluent along the baffle 39 assi,sts in purgi,ng the
' droplets in this direction and out through oil outlet 14.
To control the level of accumulated oil in chamber 24,
a plurality of oil-water interface detectors 41,- 43, and
45 schematically il'lustrated in Fig. 1 are provided in rear
wall 38 of housing 10. These detectors are conventional and
operate on the differences in electrical conductivity of
water and oil. Thus, for example, when the oil level in
chamber 24 falls below middle dectector 43, thus changing
the conductivity between detectors 43 and 45, an oil pump
(not shown~ would be activated to pull the oil out of outlet
14 and thereby prevent the oil from falling to a level where
it could contaminate the clean water outlet. Oil withdrawal
is contînued until the oil-water interface reaches detector
41 and then the pump is de-activated. This, of course,
would be the arrangement for light oil-contaminated water,
suitable modifications being made when heavy oil-contaminated
water was being passed through the system.
In operation and with reference to Figc 1, the con-
taminated feed is fed through inlet 12 into feed chamber 22
of separator 10 wherc it is evenl~ distributed throughout
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the cross-sec~ional dimensions o ~he hous~ng. The porous
regenerable material 26 meetîng the abo~e-de:Eined criterion
is typicall~ a piece of polyurethane foa~ su~stantially
filling up the space in separation cham~er 20 bounded by
e-nvelope 40 aild plates 2~ and 3a and having 60 pores per
linear inch, a thickness of approximatel~ 16 inches, and a
cross-sectional area of approximately 4 square feet. rhe
conta2,l-nated feed flows through foam block 26 where the oil
is absorbed and/or coalesced depending upon the degree of
saturation of the foam.
In the beginning, practically all of the oil is absorbed
by the foam, but after the foam begins to become saturated~
large droplets of coalesced oil start to appear in the
effluent as a result of the oily water passing through the
foam. Discharging this effluent in chamber 24, however,
permits the large coalesced droplets of the oil to be readily
separated by gravity, so that it is not necessary to shut
off the feed at this point and regenerate the foam just
because oil appears in the effluent. The separated droplets
are then withdrawn through oil outlet 14 and the heavier,
clean water through outlet 16.
The separation step cannot be sustained indefinitely.
At a certain level of oil saturation of foam pad 26, the
pressure drop across the foam increases to such an extent
that it tends to block the flow of contaminated water. The
flow of water is then stopped and regeneration of foam block
26 is accomplished by moving perforated plate 30 toward
fixed plate 28 by hydraulic cylinder 32 to compress the foam
and expel the absorbed oil. The oil expelled from the foam
3~ flows into both feed chamber 22 and ~loatation chamber 24
where it rises to the top of the chambers and ~s dra~n off
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through oil outlets 14 and 14'.
To assist in purging th.e e~pelled oi;l, clean water can
be pumped back into cham~crs 2Z and 2~ during regeneration
by pump 59, as shown in Fig. 1, to push.accumulated oil
toi~.ards oil outlets 14 and 14'. Following regeneratiorl,
hydraul~c cylinder 32 is retracted, water inlet 16' and oil
outlet 14' to feed chamber 22 are closed, and the oily water
is again fed to the separator.
By permitting gravity floatation of the effluent from
th.e polyurethane foam, both the abso.rbing and coalescing
properties of the foam can be utilized resulting primarily
in longer periods of operation between regeneration without
sacrificing the quality of the effluent or the flow rate
th.rough the separator.
During operation the feed will slip past plate 30 and
form a stagnant pool of feed water around the envelope in
the annular space 50 between the envelope and the chamber of
equal or greater pressure than that of the flow of fluid
th.rough the foam block. While this feed is still contamin-
ated, it can be seen that it cannot short-circuit the block
and pass unfiltered to chamber 24 because the downstream end
of the envelope is sealably clamped to fixed plate 28. The
presence of this pressurized pool o-f feed water keeps the
envelope out of contact with the walls of the housing and
helps to compress the envelope against foam block 26, thus
avoiding collapse of the foam and preventing channeling
between the foam block and the envelope.
D.lri.ng regenerati.on, as discussed above and as shown in
Fi~. 3, the flexible envelope folds up with the foam and
3~ keeps it out.of contact with the walls of the chamber,
thercb~ a~oid.ing friction during compression and conse~uent
wear on the su-rface of the foain and pelmitting e~pansion of
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the foam ~ack to its intial shaRe following regeneratian
for more effective filtration.
In additi.on and to Rrevent slid~ng of the foam with
respect to the envelope during compression and expansion,
the flexible envelope can be glued to the outer surface of
the foam block with a suitable polyurethane compatible glue,
such as silicon rubber, with.out departing from the scope of
th.e present invention.
The invention thus provides an improved foam block oil-
water separator that more e-ffectivel~ avoi.ds channeli.ng
wh.ile eliminating friction between the foam and the chamber
walls during regeneration.
The invention ir its broader aspects is not limited to
the specific details shown and described`and departures may
be made from such details without departing from the principles
of the invention and without sacrificing its chief advantages.
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