Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1~0~8~7
This application is a divisiona] o~ Canadian
application No. 259,685.
The present in~ention relates to an improved form
of gravity separator for mixtures of immiscible liquids
of different densities, such as, for example, oil and
water.
More specifically, the invention is an improved
gravitational separator of the type utilizing a collec-
tion tank or housing for receiving a mixture of the fluids
to be gravitationally separated, the tank having either
a floating dome or diaphragm element within the upper
area of the tank which serves as a reactiorl surface
against which the volume of lighter (less dense) fluid
accumulated within the upper portion of the tank exerts
an upward, buoyant influence.
Separators of the type utilizing a floating dome
are known in the prior art, as exemplified in the British
Patent Specification No. 1,212,553 to Cornelis in'tVeld
published November 18, 1970 and U.S. Patent No. 3,628,660,
also to in~tVeld, granted December 21, 1971. In separa-
tors of this type, the mixture of lighter and heavier
fluids (oil and water, generally) is admitted to the
interior of the separator beneath the dome under positive
pressure or is inducted therein by suction of the heavier
fluid from the heavier fluid discharge pipe of the
separator, with the sepa~ator being hermetically sealed.
The mixture of heavier and lighter fluids gravitationally
separate in the separator, with lighter fluid rising up
under the dome and heavier fluid sinking to the lower
part of the separator vessel beneath the dome.
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The gradual accumulation of lighter fluid beneath
the dome, which is counterbalanced so as to normally be
slightly negati~ely buoyant in the heavier fluid, causes
the dome to float upwardly in the heavier fluid within
the separator. It is customary to sense the high limit
poistion of the dome to produce a control signal use~ul
to instigate valve and pump actuations which enable the
removal of less dense separated fluid from beneath the
dome.
Gravitational separators of this type that are used
to separate oil from an oily water mixture are provided
with filter or coalescer screens or elements between the
lower part of the separator and the water discharge pipe
to collect any lingering droplets of oil carried to the
lower part of the separator. Such screens are backwashed
periodically to remove the oil clinging to -the coalescers
and, as described in the above-referenced U.S. Patent No.
3,628,660, such backwashing of the screens can be carried
out quite efficiently during the oil discharge mode of
separator operation. That is, it is customary procedure
to remove the accumulated oil from beneath the floating
dome by pressurizing the clean water discharge pipe of
the separator to admit clean water backwards into the
lower end of the separator through the coalescer screens,
and into the area beneath the dome to thereby force ac-
cumulated oil out of the separator under positive pres-
suxe. Only oil is discharged, of course, the reverse
inflow of water being ceased when the accumulated oil has
been discharged and the dome has sunk to its lower
3b starting level.
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Several problem areas have been encountered with
the use of separators of the type just described. There
has arisen, for example, a need for a simple, efficient
and substantially fail-safe system to precisely counter-
balance the floating dome or the diaphragm beneath which
the separated oil is trapped and to accurately sense when
the volume of separated oil has reached an upper limit
within the separator so that removal procedures can be
instigated. Particularly in instances where the specific
gravity o the oil to be separated is close to the
density of water, a need for an extremely precise means
for measuring a predetermined volume of accumulated oil is
necessary to ensure proper functioning of the separator.
Also, flow of water through the coalescer screens has
been found to be less than ideal both in a forward and
reverse flush sense. Ideally, flow in a forward direction
through the coalescer screens should be uniform across all
of the screens in the system and when the screens are
backflushed, the backflush flow should occur entirely
across the surfaces of the coalescer screens to remove oil
droplets therefrom and furthermore, the discharge of oil
from between the coalescer screens should be as complete
as possible during the backflush operation. Finally, it
has been found to be highly desirable to prevent any ac-
cumulation of oil above the separator dome (or diaphragm)
during the operating life of the separator, since ac-
cumulation of the less dense fluid above the dome causes
an inaccurate flotation response of the dome to the ac~
cumulated oil beneath the dome,
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One approach to the dome counterbalance problem has
been described in U.S. patent No. 3,957,638, qranted on May 18,
1976. In this patent, which is incorporated herein by
reference, a complete description is provided of a prior art
dome balancing system and separator control system which the
present invention is intended to improve upon. It should be
noted that, although not illustrated in that patent, the prior
art balancing and control system was pneumatically operated.
The complex balancing system of levers, weights, pivoted shafts,
bearings and seals was found to be cumbersome and heavy as well
as costly to fabricate. Moreover, an electronic control system
has been found to be far more desirable than the electrical
system illustrated in that application and the pneumatic system
previously in use.
The present invention finds particular application in
a bilge water disposal system for a vessel, such as described
in U.S. patent No. 4,018,683, granted on April 19, 1977. Other
applications of the present invention, of course, are
envisioned in static, industrial installations for separating
mixtures of immiscible fluids of different densities.
The present invention contemplates a simplified,
dependable means for adjustably balancing the floating dome or
the floating diaphragm means, (sometimes simply referred to as
the "reaction member" or the "floatation force responsive
member"), used to sense the accumulation of lighter fluid in a
specific type of gravity separator. The improved balance
system in effect enables the precise sensing of a predetermined
volume or weight of lighter fluid wi-thin the separator and the
generation of a control signal in response to the sensed
condition for controlling flow valves and a pump to thereby
regulate the operation of the separator. The separator has
specific application for removing oil from oily water mixtures
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and will be hereinafter referred to in this context, although
the invention is broadly contemplated as having utility in con-
nection with the separation of any fluids of different
densities.
In general, the floating element in the separator is
connected directly to a first adjustable mass or weight for
balancing the floatable element within predetermined lower limits
of floatation and is arranged to directly engage a second mass
or weight when the floating element reaches a higher level of
floatation. The system of weights enables the floating element
of the separator to be free to continuously float in the
separator within upper and lower limi'cs, while the degree of
buoyancy of the floatable element is varied between floatation
limits.
The entire balance system is located within the
separator housing and magnetic responsive switches or the like
located outside the housing respond to the position of a
permanent magnetic element attached to the dome or diaphragm
within the housing and which is intended to transmit the move-
ment of the dome or diaphragm through the magnetic switches.The entire interior of the separator tank therefore can remain
hermetically sealed while an external signal can be derived of
the dome or diaphragm position at upper and lower limits to
sense the presence of a predetermined accumulation of oil
beneath the dome or diaphragm.
A visible indication of the position of the floating
-- reaction member is obtained by constructing the portion of the
housing adjacent the magnetic switches from transparent material
or fabricating transparent windows in this area through which
operation of the system can be visually monitored, if desired.
Finally, the present invention contemplates the
provision of a particular form of flexible seal means beneath
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`` ~ 7
the floating unit of the separator in combination with a pres-
sure balancing conduit to eliminate the possibitlity o oil
gathering above the floating member.
The invention claimed in the present divisional application
is a gravitational oil and water separator utili2ing at least
one coalescer screen wîthin the lower area of the separator-
for trapping oil particles entrained in a clean water dis-
charge flow from the separator, the water discharge from the
separator occurring normally by suction of water from the
separator and the screen normally being backflushed by a
reverse flow of water through the screen under pressure, the
separator including a water discharge outlet and backflush
inlet means at the lower portion of the separator. The improve-
ment, according to the invention, comprises a chamber within
the separator for containing the coalescer screen, the chamber
being isolated rom the interior o the separator except
through pressure responsive one-way valve elements and the
below-recited water discharge outlet and backflush inlet:
said one way valve elements comprising at least one inlet
pressure responsive one-way valve for permitting flow of water
into the chamber only~ and at least one pressure responsive
one-way outlet valve for permitting flow of water out of the
chamber only. The said water discharge outlet and backflush
inlet of the separator communicates with the interior of the
chamber. Also, the inlet one-way valve is located towards the
lower end of the chamber and the outlet one-way valve is
- ` located at an upper end of the chamber. Furthermore, the
coalescer screen is disposed in the chamber entirely across
the chamber with the water discharge outlet and backflush
inlet means being located on one side of the screen and said
inlet and outlet valves being located on the opposite side of
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the screen~ In this manner, the flow o water into the chamber
during normal separator ~eration enters at the lower space
of the chamber through the pressure responsive one-way inlet
valve and backflush flow out of the chamber occurs at the
upper extremity of the chamber during the backflush operation
of the separator through the pressure responsive one-way
outlet valve to thereby ensure the discharge of backflushed
oil out of the upper area o the chamber.
A preferred embodiment of the invention is characterized
in that the coalescer screen chamber is located centrally in
the lower area o the separator and includes top and bottom
walls extending substantially horizontally across the interior
of the separator, and characterized further by a duct extending
generally vertically through the coalescer screen chamber and
through the top and bottom walls thereof, the duct being in
communication with the interior o the separator but not with
the interior o the chamber, whereby the flow o water pro-
.ceeds from the upper portion o the separator down through
said duct, and upwardly into said chamber through said inlet
~0 check valve.: .
: The above general summary of the invention is intended
to be introductory with respect to a detailed description of a
specific, illustrativ embodiment of the invention that is
. set forth below~ Of course,.the scope o the invention is
intended to be limited solely by the claims set forth below,
with the detailed description describing a preferred embodi-
ment of the invention, illustrated in the appended drawings,
in accordance with statutory reqairements and ~ __ =
,
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With reference to the attached drawings:
EIGURE 1 is a schematic view of a floating domeseparator system incorporatin~ the dome balancing and
position sensing system of the present invention, and
the coa~escer screen improvement;
FIGURE 2 shows the details of the coun~erbalance
and position sensing system with a floating dome
element;
FIGURE 3 is a view similar to FIGURE 2, only
shows the counterbalance mechanism used with a floating
diaphragm element and a pressure equalizing conduit; and
FIGURE 4 shows the counterbalance used with a sealed
floating dome element and a pressure equalizing conduit.
~ith reference to Figure 1 of the drawings, a
separator system for separating oil from oily water includes
a separator tank 10 having an oily water mixture inlet
conduit 12 that continues internally of the separator ta*k
10 up to an upwardly extending extremity 14 which cons-
titutes the actual inlet for oily water mixture within
the tank 10. Inlet conduit 12 includes a one-way check
valve 15 at the source M of oily water mixture to be
processed. A water line 16 located towards the lower
end of the tank 10 serves as both a clean water discharge
line and a backflush/tank pressurizing inlet line, as
will be more fully explained below. Line 16 is connected
to suction pump 18, through line 17, solenoid valve 19 and
one-way check valve 20, the pump 18 being connected to a
control panel 22 which provides a power supply for the
pump and controls its operation throu~h lead 24. The
solenoid valve 19 is connected to the control panel through
lead 25. Line 26 is the outlet line for clean water proces-
sed by the separator system. Conduit 16 is also connected
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to a clean water supply under pressure through solenoid
valve 28 which is connected to control panel 22 through
lead 29.
Normally, the tank or housing 10 is initially filled
with water or contains oil and water undergoing separation,
the valve 19 is normally opened and valve 28 is normally
closed. Actuation of pump 18 then draws a suction on line
16 which, since the tank 10 is hermetically sealed, causes
discharge of water through line 16 from tank 10 and intake
of oily water mixture line 12 into the tank. Since the
mixture from source M is not agitated, emulsified or
homogenized by a pump located between the source M and the
separator tank 10, but rather is quietly released at the
top of the upstanding column of conduit 12 in separator
10, separation by gravity of oil and water process rather
rapidly within the tank 10.
A dome element 30 loosely fits within tank 10 and
may be provided with flotation cha~bers 32. The dome 30
will be counter-balanced to have slightly negative buoy-
ancy in water (fresh or salt water, as the situation
demands) so that with no oil whatsoever in the separator
the dome rests on lower stop means 34.
oil discharge conduit 36 extends to a position at the
extremity 38 thereof within the tan~ 10 just beneath the
inner surface of the top of the dome 30 when the dome is
in its lower extreme rest position on the stop 34. The
other end o.f conduit 36 empties into an oil storage tank
40 through one-way check valve 41. Inlet line 12 dis-
. charges at 14 in an area beneath the dome 30.
Thus, it will be evident that upon operation of
pump 18 in the normal manner, oily water mixture is sucked
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into the tank 10 and discharged gently benea-th the dome
30, with the water dropping down to the lower part of
the tank and the oil rising to the upper internal area
beneath the dome 30. The dome 30 will then be influenced
by the buoyancy of oil trapped beneath the dome 30, which
buoyancy will be a function of the relative densities
of the oil and water and the volume of the oil accumu-
lated beneath the dome. The reaction of the dome to the
buoyancy force of the accumulated oil will be a tendancy
to float upwardly to the extent that the buoyancy force
is unbalanced. If the dome 30 were floating with initial
neutral buoyancy, for example, the presence of any
appreciable amount of oil under the dome 30 would cause
it to gradually rise to an upper limit in the tank 10.
It will be readily understandable that this is not
desired, since the objective o the separator system is to
cyclically accumulate a certain volume of oil beneath the
dome, and to discharge substantially all of this oil into
a collection tank with a minimum of interruption to the
overall separatory process. A balancing system for the
dome is therefore desirable to enable the accumulation of
a predetermined volume of oil beneath the dome and means
for sensing the occurrence of such predetermined accumula-
tion in a precise manner. Once the accumulation of a
desired volume of oil has occurred, control means for
the separator must sense the occurrence of this accumula-
tion and institute control of the system to momentarily
cease the inflow of oil and water mixture, pressurize the
interior of the tank with water to cause the oil to be dis-
charged from the separator and finally to return the system
to its original operating mode when sufficient oil has been
removed from the system.
--10--
' ` `
The dome balancer system provided by this nvention
will be described momentarily, but another characteristic
of the separator should first be understood. Upon shutting
off of pump 18, and with the closure of valve 19 and open-
ing of valve 28, water under pressure is admitted quickly
into the tank 10. The check valve 15 prevents outflow
through conduit 12, with the consequent result that oil is
discharged through conduit 36, the only other outlet from
the separator tank~ The inlet of conduit 36 is located
beneath the dome 30 but closely adjacent the upper surface
of the dome when it is in its lowermost position. Oil will
therefore be discharged through conduit 36 as the interior
of tank 10 is pressurized with fresh water and the dome
will gradually sink as the oil is discharged from the
separator, since the volume of oil causing the upward
buoyant force on the dome is gradually diminished, If the
inflow of fresh water through line 16 is continued in-
definitely, of course the oil would all be removed, the
dome 30 would settle onto its stop, and water eventually
would ~e discharged through oil discharge conduit 36.
Obviously, this condition is never intentionally allowed
to occur, as will become evident in the ensuing description.
In the drawings, for visualizing the various fluid
levels within tank 10 during normal operation, oil is
indicated as 42, and water as 46.
With reference to Figures 1 and 2,the improved dome
balancing means includes an upwardly extending shaft or
rod element 50 connected directly to the upper end of dome
30. Obviously, the connection bet~leen the rod 50 and the
dome is made at the upper central area of the dome for the
sake of simplicity and convenience. Rod 50 could be
.
connected to any part of the dome 30 50 long as it moves
directly in proportion to the movement of the dome itself,
or is capable of transmitting such proportional movement.
Rod 50 extends through a guide opening 52 in apertured
plate 54 and is provided with a shoulder at 56 upon which
may rest a first weight securing means 58 in the form of a
base plate 60 having an opening 62 thereon and having an
internally threaded tube 64 welded thereto so that it ex-
tends coaxially with the opening 62. The weight securing
means 58 itself may constitute one of the weight elements.
The central opening 62 in plate 60 is dimensioned smaller
than the larger dimension of rod 50 so that plate 60 will
always rest on the shoulder 56 of rod 50. The upper, smal-
ler portion of rod 50, of course, enables the removal and
placement of plate 60 on the shaft 50 from above. The upper
extremity of rod 50 is provided with a permanent magnet
element 66 removably secured to the rod 50.
Threadably received on tube 62, through which the
larger dimension of shaft 50 extends freely, are weight
masses in the form of plates 72, the plates 72 being
readily secured to or removed from the tube 62, and being
of variable size and mass to enable precise adjustment of
the total weight of the first weight means 58 on shaft 50.
It will be readily appreciated that the total initial weight
of the dome and its attachments as illustrated in Figures 1
and 2 will be the equivalent of the weight of the dome it-
self, the shaft 50, the first weights 58 and the magnet
66, along with the weight of structure connecting these
elements. The buoyancy of the dome 30 therefor, and the
structure directly connected thereto, will depend upon the
weight of the water displaced by the assembly as compared
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8Qq
to the weight of the assembly itself. The first weight
means 58 actually adjusts the buoyancy of the dome 30 so
that it can be made precisely negatively buoyant to the
desired degree.
Surrounding rod 50 and extending above the tank 10
is a housing 68 for the dome balancing systeml the housing
68 being secured such as by welding to the tank 10. The
tank 10 is provided with an upper opening 70 located below
the housing 68. A horizontal support shoulder surface 74
is provided within housing 68 and an upper cover 76 is
releasably secured to the top opening 78 of the housing
68. An air eliminator valve 80 of conventional design
is provided in the cover 76. Cover 76 furthermore is
provided with a central opening 82 through which the upper
extremity of rod 50 freely extends during normal operation
of the separator. A transparent cover 84 is secured to
the cover 76 over the opening 8~, the cover 84 preferably
being made of strong plastic material.
Externally of the cover 84 magnet sensitive relay
~ Z switches 86 and 88 are placed in position where they may
; be tripped by the proximity of magnet 66 within the cover
84 as the rod 50 moves up and down with the movement of the
dome 30. Such magnetic sensitive switches are conventional
per se, the particular advantage of their use here is that
- the tank 10, housing 68 and cover 84 can be hermetically
sealed, yet the floating position of the dome 30 can be
remotely sensed externally of the separator tank. The
transparent nature of the cover 84 also enables one to
make a visual check of the operation of the system. Special
seals, shafts and bearings are therefore eliminated by
using the present invention.
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.
''"'` '
Switches 86 and 88 respectively sense low and high
dome positions, and are connected to control panel 22 via
leads 90 and 92.
A second set of weight masses are provided within
housing 68 in the form of stacked plates 94 resting on the
shoulder surface of ledge 74. The plates 94 have an en-
larged, central opening 96 through which a portion of rod
50 freely extends. Significantly, however, the opening
96 will not accommodate the plate element 58, whereby,
upon upward movement of rod 50 to the point that the upper
side of plate 58 contacts the undexside of the lowermost
plate 94, continued upward movement of rod 50 will raise
the second weights 94 along with the base plate 60 and
weights 72.
Thus, the buoyancy of dome 30 will be adjustably
balanced in two phases by the present system in an entirely
passive manner. The upward flotation of dome 30 initially
will be resisted by the gravitational pull on the first
set of weights 72. Flotation of-the dome further upwardly
beyond the point where plate 58 contacts the second set
of weight means 94 will be resisted by the gravitational
pull on the combined masses of weights 72 and 94. By
varying the masses of the weight elements, the balance
forces on dome 30 can be precisely regulated to ensure
that a predetermined volume or weight of oil 42 trapped
under the dome will be accumulated before the dome can reach
an upper flotation position. Moreover, the high limit
switch 88 can be precisely positioned to sense accurately
when the buoyancy of the dome and the accumulated oil
3U beneath the dome exceeds the balancing force of the com-
bined weights 72 and 94.
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In operation, the tank 10 is initially ~illed with
water approximately to the level of the tank cover 76, pre-
ferably by closing valve 19 and opening valve 28 to cause
fresh (or salt) water to be admitted into the tank through
line 16. Check valve 15 prevents outflow through inlet
line 12 beyond the valve 15, but line 12 can also be closed
by an appropriate shut off valve. Line 36 is likewise
closed during the filling operation. The tank 10 is hermetic-
ally sealed, with air being exhausted out the air eliminator
80. Suitable switches at the control panel are then thrown
to cause the system to operate in the automatic mode. Valve
28 is closed, valve 19 is open and lines 12 and 36 are in
communication respectively with an oil and water mixture M
and a storage tank 40. Suitable weights 72 have been
placed on rod 50 to cause the dome to rest at its lower
limit. Operation of pump 18 can be regulated in any suitablé
manner, such as, for example, where mixture M is located
in a bilge of a vessel, by a switch means response to the
bilge water level, and when functioning creates a negative
suction pressure in tank 10. As water is withdrawn through
line 16 and discharged through line 26, oil and water mix-
ture is drawn into the separator through line 12. In the
separator, oil will float towards the underside of the
dome 30, while water will gradually drop to the lower area
of the tank. The volume of water displaced from beneath
dome 30 will create an upward flotation force on dome 30
which force will be a function of the relative densities
of the oil and water, and the mass of the volume of oil
accumulated between the dome. Stated in a different manner,
the force is a function of the relative densities of the oil
and water and the mass of the volume of water displaced by
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the oil beneath the dome. Initially, upward flotation
of the dome will be resisted by the downward force of
weights 72 on shaft 50, and low dome position switch 8
will sense this condition and transmit an appropriate
signal to control panel 22. As the mass of oil beneath the
dome increases, the buoyancy forces acting on the dome in-
crease and the weights 72 will be raised along with the dome
until the second set of weights are engaged. Continued
accumulation of oil then causes the total weight system
to be lifted by the dome, but this condition will virtually
instantly be sensed by the high position switch 98 which
will transmit a signal appropriate for this condition to
control panel 22.
The high dome position, of course, is indicative of the
accumulation of a predetermined volume or weight of oil
beneath the dome that must be discharged ~rom the separator
periodically. Control panel 22 includes appropriate circui-
try to utilize the signal transmitted by the high dome
position switch 88 and to send an appxopriate signal to
cease operation of pump 18, close valve 19 and open valve
28. This causes further mixture input to the separator
to cease, and forces fresh water under pressure into
the tank 10 to cause oil to be discharged from line 36 to
storage tank 40, as described above.
Outflow of oil from beneath the dome will cause it
to sink towards its starting position until the low dome
position switches sense a low position of the dome and
control panel 22 responds to this condition. It will be
apparent that once the second set of weights 94 rest on
the shoulder 74 of housing 68, the downward ba:Lancing
force exerted on dome 30 will be reduced. However, oil
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discharge is programmed to continue until a low dome
position is sensed by the low dome position switch 86.
Circuitry within the panel will then return the system
to its original mode of operation whereby valve 19 is
opened, valve 28 is closed and operation of pump 18 is
enabled. Continued operation of pump 18 will cause con-
tinued recycling of the system so long as sufficient oil
accumulates beneath the dome to cause it to reach its
upper flotation limit. For a suitable example of a control
panel and pump control system applicable to the present
lnvention, reference is made to the above-cited U.S.
patent 4,018,683.
Coalescer screens 100 (loosely referred to as filters)
are provided at the lower end of tank 10, the screens being
concentrically nested about a central conduit 102 which
extends downwardly through the screen assembly and slightly
- beyond the bottom of a lower screen support plate 104.
Upper screen support plate 106 alony with lower plate 104
extends transversely across the tank internal dimension,
and, along with the conduit 102, effectively seals the
tank 10 from a filter chamber 110 which contains the screens
100 and which communicates with water outlet 16.
Flow of water into chamber 110 is through lightly
loaded one-way check valve 112 which allows water to be
admittéd to the chamber 110 from below the lower plate 104.
Inflow of water to chamber 110 occurs between the duct 102
and the innermost coalescer screen.l00 when pump 18 is
operating~ The water then passes radially outwardly through
the successive screens 100 and finally out through line
16. Oil droplets that may be entrapped in -the sinking
water beneath the dome and not separated out in the main
.
1~ 3{)7
mass of oil 42 are caught up on the coalescer screens,
which are preferably formed of an oleophobic porous,
fibrous material, woven or knitted, rough on one side
and smooth on the other side, the screens being supported on
a vertical metal or plastic framework. As illustrated,
the screens preferably are concentric and cylindrical in
form.
The screens 100 are backwashed during tile oil discharge
operation when the tank 10 is pressurized by incoming
water through line 16. One-way check valves 114 provided
in the top plate 106 provide the only outlets for
chamber 110, whereby, inflow of water to chamber 110
through line 16 will reverse flush the screens 100 and
discharge water and backflushed oil particles from the
chamber areas between the screens 100 into the tank 10
above plate 106. An oil detector 120 connected to panel
22 via lead 122 is provided within tank 10 above the
screens 100 to detect excessive oil at this level of the
separator~ Actually, detector 120 can be located at any
desired position beneath the dome 30 and above the screen
support plate 106. If oil in an emulsion state with water ,
reaches the coa]escers 100, oil could be passed through the
screens and into the water discharge line. Also, excessive
oil at this level of the tank 10 would be indicative of a
~" - malfunction in the separator control system. If this situa-
tion is sensed at the detector probe 120, appropriate
circuitry at control panel 22 will shut down the separator
system and sound an appropriate alarm.
Referring to Figure 3, the dome balancing system
shown in Figures 1 and 2 is illustrated with a floating
diaphragm member 200 in tank 10. A flexihle imperforate
seal element 202 enables free-floating action of the
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diaphragm member 200 in water within tank 10, while flo-
tation chambers 204 provide buoyancy for the member 200.
A pressure equalizin~ pipe 206 provides communication
between the areas 207 above member 200 and the lower part
of tank 10 adjacent or below the filter chamber 208, which,
in this embodiment, includes an outer peripheral wall 210
which provides a chamber 212 which communicates freely with
the water at the lower area of the tank 10 outside the
filter chamber 110.
In this embodiment of the invention, an upper guide
element 214 for rod 50 is provided in addition to the lower
guide 52 to stabilize the rod action.
It will be readily observed that the principle of
operation of this embodiment is similar to that of the dome
unit, only the oil in this configuration is accumulated
beneath the floating diaphragm assembly 200 and 202.
In Figure 4, a floating dome elemen-t 300 is provided
at the top end of a larger tank 10, and bellows or the
like seal 302 is provided beneath the dome to prevent leak-
20 , age of oil around the bottom of the dome 300. A pressure
equalizing conduit 304 provides communication between the
water chamber 306 above dome 300 and the lower port:ion 308
of tank 10 below the lower filter plate 104. The seal 302
in this instance is formed in such a manner that free move-
ment of dome 300 is unimpeded in a vertical sense and
the seal element itself does not react to the buoyant force
of oil in the upper area of the tank 10 in a vertical sense.
This can be accomplished, for example, by using a bellows
element extending substantially vertically between the lower
periphery of dome 300 and the deflector ring forming the
periphery of opening 310 in the upper part of tank 10.
The horizontal cross-sectional
-- 19 --
area between the dome 300 then will be constant all the
way down to the top of the tank, and the buoyancy forces
due to accumulated oil beneath the dome will not ba reacted
vertically by the seal 302. A second flexible seal 305
may be provided at the bottom of conduit 304 to further
prevent oil contamination in the chamber 306 above the
dome 300.
The above description is intended to be exemplary of
preerred embodiments of the present invention, modifications
10of these embodiments and different arrangements of specific
structure falling within the scope of the appended claims
are intended to be encompassed by this patent.
1 .
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