Note: Descriptions are shown in the official language in which they were submitted.
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Title: PRE-TREATMENT AIR/LIQUID SEPARATION APPARATUS
FOR FLUID STREAMS AND METHOD OF USING SAME
FIELD OF THE INVENTION
This invention relates generally to separation systems for
fluid streams that include a gaseous component and a liquid
component. In one embodiment, the invention relates to air/liquid
10 separation apparatus for multi-phase liquid streams such as those
obtained during vacuum extraction environmental remediation
treatments. Such streams may include water/hydrocarbon mixtures.
BACKGROUND OF THE INVENTION
Various parts of the environment are contaminated with
liquids which are non-miscible with water such as petroleum and its
derivatives. These may be present in free water, such as ponds, rivers
and the like, or else present in the subsurface such as in groundwater.
One method of remediating a site contaminated with such
20 non-miscible liquids is to use a vacuum to extract a stream, including
the non-miscible liquid, from the site and to subject the resultant
multi-phase stream to air/liquid separation. One method of capturing
such a liquid is to insert a hose into the site and to withdraw such a
stream. In many applications, such streams will also include air and,
25 in some cases, solids, such as soil in the case of groundwater.
Several alternate methods have been used to separate air
from such multi-phase streams. For example, according to one
method, the feed stream containing both air and a multi-phase liquid
are passed through a pump. The liquid is subsequently collected in a
30 pressurized liquid separator which may then be evacuated using the
elevated pressure in the liquid separator. One disadvantage of this
approach is that pumping the multi-phase feed stream through a
pump increases the emulsification of the non-miscible liquids thus
increasing the difficulty of subsequently separating the non-miscible
35 liquids. A further disadvantage is that the pump may have difficulty
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handling a feed stream having a high sediment loading or dissolved
Fe, Mn and/or Ca.
A second alternate method is to install a cyclone separator
on the intake end of a vacuum pump. The liquid collected in the
5 separator is evacuated by means of a moyno pump. One disadvantage
of this ~y~tem is the high capital cost of a moyno pumps and their
power consumptions. Further, the moyno pump is an additional piece
of equipment which requires maintenance and which may break
down therefore incurring potential additional down time.
A further alternative method is to install a cyclone
separator upstream of a vacuum pump. At intervals, the vacuum is
taken off line allowing liquid which has accumulated in the separator
to drain from the separator by gravity. One disadvantage of this
approach is that the system operates on a non-continuous basis.
15 During site remediation, it may not be desirable to interrupt the
extraction of the multi-phase liquid. A further disadvantage of this
system is that high flows of liquid may decrease the vacuum in the
system before a full vacuum is achieved on the extraction point. In
order to overcome these problems, two air-liquid separators may be
20 installed in parallel and the feed may be cycled between the two units
so as to provide a continuous vacuum source. One disadvantage of
such a modification is that increased manifolding is required as well as
additional control systems. Further, site remediation equipment is
typically mounted on a mobile platform and the addition of a second
25 liquid separator increases the footprint of the mobile platform.
SUMMARY OF THE PRESENT INVENTION
In accordance with the instant invention there is provided
a cyclonic separator having an inlet port for introducing an air/liquid
30 inlet stream tangentially into the cyclonic separator, an upper portion,
an air outlet port positioned in the upper portion and adapted to be
connected to a vacuum source positioned upstream from the air outlet
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port for providing fluid suction to the inlet port, a lower portion, and a
liquid outlet port positioned in the lower portion; a collecting tank
positioned below the cyclonic separator having a liquid inlet port in
flow communication with the liquid outlet port of the cyclonic
5 separator via a transfer pipe, a liquid outlet port having an associated
valve operable between an open position and a closed position for
draining the collecting tank and an air inlet port having an associated
valve operable between an open position and a closed position for air
entry into the collecting tank as the collecting tank is drained, the
10 transfer pipe having an associated valve operable between an open
and a closed position for alternately permitting liquid to flow through
the transfer pipe into the collecting tank and isolating the cyclonic
separator from the collecting tank; and, a vent pipe extending between
the cyclonic separator and the collecting tank to maintain the cyclonic
15 separator and the collecting tank at the same pressure, the vent pipe
having an associated valve operable between an open position and a
closed position.
In accordance with another embodiment of the invention
there is provided an air/liquid separation apparatus comprising an
20 air/liquid separator having an inlet port, an upper portion, an air
outlet port positioned in the upper portion, a lower portion and a
liquid outlet port positioned in the lower portion; the air outlet port
adapted to be connected to a vacuum source positioned upstream from
the air outlet port for providing fluid suction to the inlet port; a
25 collecting tank having a liquid inlet port in flow communication with
the liquid outlet port of the separator via a transfer pipe, a liquid outlet
port and an air inlet port, the transfer pipe having an associated valve
operable between an open and a closed position for alternately
permitting liquid to flow through the transfer pipe into the collecting
30 tank and isolating said separator from the collecting tank; a vent pipe
extending between the separator and the collecting tank to equalize the
pressure in the separator and in the collecting tank, the vent pipe
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having an associated valve for isolating the separator from the
collecting tank.
In accordance with a further embodiment of the
invention, there is provided a method of separating an air/liquid feed
5 stream into a liquid stream and an air stream comprising the steps of
introducing the feed stream into a separator having an inlet port, an
upper portion, an air outlet port positioned in the upper portion and
connected to a vacuum source positioned upstream from the air outlet
port for providing fluid suction to the inlet port, a lower portion and a
10 liquid outlet port positioned in the lower portion, the liquid outlet
port being in flow communication with a collecting tank via a transfer
pipe, the collecting tank having a liquid outlet port and an air inlet
port, the transfer pipe, the liquid outlet port and an air inlet port
having associated valves operable between an open and a closed
15 position, the pressure in the separator and the collecting tank being
equalized by a vent pipe extending between the separator and the
collecting tank, the vent pipe having an associated valve for isolating
the separator from the collecting tank; closing the valve associated
with the transfer pipe when the collecting tank is full whereby the
20 flow of liquid through the transfer pipe is stopped and the liquid
separated from the feed stream is collected in the lower portion of the
separator; closing the valve associated with the vent pipe to isolate the
collecting tank from the vacuum source and opening the air inlet port
to permit air to enter the collecting tank; opening the valve associated
25 with the liquid outlet port of the collecting tank to permit the
collecting tank to be drained; closing the valves associated with the
liquid outlet port of the collecting tank and the air inlet port when the
collecting tank has been drained, and opening the valve associated
with the vent pipe and then opening the valve associated with the
30 transfer pipe to drain the liquid which has accumulated in the lower
portion of the separator into the collecting tank.
In one embodiment, the collecting tank is operable so as to
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be in flow communication with the source of pressurized air. The
pressurized air assists in the draining of the collecting tank and
therefore decreases the required cycle time to drain the collecting tank.
In order to maintain a constant extraction, the lower portion of the
separator is preferably sized to collect the liquid separated from the
inlet stream when the transfer pipe is closed and the collecting tank is
being drained. By using pressurized air to assist in the draining of the
collecting tank, the size of the lower portion may be decreased or,
alternately, higher liquid flow rates may be accommodated while the
collecting tank is being drained.
The apparatus of the instant invention provides a
simplified apparatus for separating a gas such as air from a liquid
stream. A further advantage is that mixing of the air/liquid feed
stream is minimized thereby reducing the emulsification of any non-
miscible liquids which may be present in the feed stream. A further
advantage of this system is that the amount of equipment which is
required for the air/liquid separation, as well as the size of the
equipment, is reduced.
DESCRIPTION OF THE DRAWING FIGURES
These and other advantages of the instant invention will
be more fully and completely understood by reference to the following
description of a preferred embodiment of the invention in which:
Figure 1 is an elevational view of an air/liquid separator
according to the instant invention;
Figure 2 is a cross section along the line 2-2 in Figure 1
and,
Figure 3 is an enlargement of area A of Figure 1.
DESCRIPTION OF PREFERRED EMBODIMENT
According to a preferred embodiment, air/liquid separator
10 comprises separator 12 having inlet port 14, air outlet port 16 and
liquid outlet port 18, collecting tank 20 having inlet port 22 and liquid
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outlet port 24 and transfer pipe 26 extending between liquid outlet port
18 of separator 12 and inlet port 22 of collecting tank 20.
The feed stream which is fed to separator 12 via inlet port
14 may be any stream comprising a gas and liquid which requires the
5 gas to be separated from the liquid. The feed stream may further
include solid or semi-solid material such as sediment, sludge and/or
biomass. The solid or semi-solid material will be separated with the
liquid from the gaseous component of the ~yslem. The separated
liquid/solid mixture may subsequently be treated to separate the solid
10 component from the liquid component by means known in the art.
The liquid component of the feed stream preferably includes at least
two non-miscible liquids which require separation. The liquid
component may comprise water and a liquid which is non-miscible
therewith. The non-miscible liquid may comprise a hydrocarbon such
15 as petroleum or a petroleum bi-product (e.g. gasoline, fuel oil, waste
oil and the like). The gaseous component typically comprises air which
is entrained with the feed stream to inlet port 14 and may also include
gaseous vapours evolved from the non-miscible liquid.
The feed stream may be obtained from free water, such as
20 a pond, a river or other source which is contaminated with a non-
miscible liquid. Alternately, the feed stream may be obtained from
access wells installed into the subsurface water table.
A vacuum source is connected upstream from outlet port
16 and is in flow communication therewith. The vacuum source may
25 be a vacuum pump or other means for providing a vacuum such as
venturi type pumps. As will be appreciated, during operation of
separator 12 when separator 12 is in flow communication with
collecting tank 20, collecting tank 20 is maintained as a closed system
so that the vacuum source may draw the feed stream through inlet
30 port 14 into separator 12. A hose or other attachment (not shown) may
be attached to inlet port 14. A nozzle or other liquid pick-up means
(not shown) may be affixed to the distal end of the hose and inserted
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into the subsurface groundwater or other location which requires
removal of liquid.
Separator 12 may be any air/liquid separator which
operates under vacuum and is preferably a cyclonic separator. As
5 shown in Figure 2, separator 12 is a cyclonic separator having an
interior surface 28 which, in cross-section, is cylindrical. Inlet port 14 is
positioned such that the feed stream enters cyclonic separator 12
tangentially thereto forcing the liquid component of the feed stream to
travel around interior wall 28. Rotation of the liquid components
10 around interior wall 28 causes the liquid components to travel
downwardly towards the lower portion of cyclonic separator 12 and,
eventually, to outlet port 18 which is positioned therein. The cyclonic
action in the separator substantially separates the air and vapour
components of the feed stream from the liquid components. The air
15 and any vapour components are drawn upwardly through cyclonic
separator 12 and through air outlet port 16 by the vacuum source.
It will be appreciated that any solid components present in
the feed stream will be generally entrained with the liquid
components and carried downwardly to outlet port 18. An access port
20 (not shown) may be provided in cyclonic separator 12 to permit
cleaning of cyclonic separator 12 as may be required, such as to remove
built up sediments which may adhere to interior wall 28.
Collecting tank 20 may be of any particular configuration
and size to permit collecting tank 20 to collect liquid which is separated
25 from the feed stream in cyclonic separator 12. Collecting tank 20 may
be supported on a base 30 having leg supports 32.
As the quantity of liquids which require treatment are
generally large, it is preferable to have liquid/air separator 10 mounted
so that it may be transported to a site and, also, from one position to
30 another within a particular site. Accordingly, air/liquid separator 10
may be mounted in a trailer, truck, skid or other mobile platform. Base
30 may be the bed of a trailer, truck, skid or other mobile platform or
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may be secured to the bed of a trailer, truck, skid or other mobile
platform by bolts or other means known in the art.
Transfer pipe 26 extends between outlet port 18 of cyclonic
separator 12 and inlet port 22 of collecting tank 20. As shown in Figure
5 1, cyclonic separator 12 is positioned above collecting tank 20 and
transfer pipe 26 comprises a relatively short vertical pipe. In operation,
the liquid separated from the feed stream flows downwardly by gravity
through transfer pipe 26 into collecting tank 20.
Cyclonic separator 12 may be positioned at any location
10 with respect to collecting tank 20 provided that the configuration of
transfer pipe 26 does not unduly impede the flow of liquid from
cyclonic separator 12 to collecting tank 20. Preferably, collecting tank 20
is positioned directly below cyclonic separator 12 as shown in Figure 1.
A pump or other metering equipment may be associated with transfer
15 pipe 26 to assist in transferring liquid from separator 12 to collecting
tank 20.
Valve 34, which is operable between an open position and
a closed position, is positioned in transfer pipe 26. When valve 34 is in
the open position, liquid may flow through transfer pipe 26 into
20 collecting tank 20. When valve 34 is in the closed position, the flow of
liquid through transfer pipe 26 is terminated and the separated liquid
then accumulates in the bottom of cyclonic separator 12. Valve 34 may
be any valve known in the art. As shown in Figure 1, valve 34 is a
pneumatic wafer valve which is operated by air supply 70 (such as a
25 compressor) via air feed line 38.
Discharge line 40 is provided downstream of liquid outlet
port 24. Valve 36 is provided in discharge line 40. Valve 36 is operable
between an open position, in which liquid collected in collecting tank
20 may be drained from collecting tank 20, and a closed position in
30 which discharge line 40 is closed. While collecting tank 20 fills with
liquid, it is operated under vacuum. Valve 36 may be a ball check
valve which will remain in the closed position while collecting tank
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20 is at sub-atmospheric pressure.
Collecting tank 20 is also provided with an air inlet port
42. When valve 34 is opened, and liquid is draining from cyclonic
separator 12 into collecting tank 20, it is desirable to maintain a
constant vacuum level in both collecting tank 12 and cyclonic
separator 12. Any venting means to equalize the vacuum in collecting
tank 12 and cyclonic separator 12 may be used. For example, a vent line
may be incorporated as part of transfer pipe 26. Alternately, vent pipe
44, which extends between cyclonic separator 12 and inlet port 42 of
collecting tank 20 may be provided. Valve 46, which is operable
between a first position in which vent pipe 44 is open and a second
position in which vent pipe 44 is closed, may be provided in vent pipe
44. When valve 46 is open, vent pipe 44 comprises an open conduit
extending between collecting tank 20 and cyclonic separator 12 to
maintain a similar vacuum level in both units. When valve 46 is
closed, vent pipe 44 is closed and will not equalize the vacuum in
cyclonic separator 12 and collecting tank 20.
In order to assist in draining tank 20, a fluid, preferably air,
is provided to collecting tank 20 to neutralize the vacuum therein and
to permit the collected liquid to drain therefrom. The air may be
provided to collecting tank 20 through an inlet port from any available
source. For example, a valve of an inlet port may be opened permitting
air to flow into collecting tank 20.
As shown in the preferred embodiment of Figure 1, when
valve 46 is moved from a first position in which vent pipe 44 is open,
to the second position in which vent pipe 44 is closed, valve 46 may
also vent collecting tank 20 to the atmosphere thus permitting air to
enter collecting tank 20 so that collecting tank 20 may be drained.
Preferably, pressurized air is used to assist in draining
collecting tank 20. Thus, as shown in Figure 1, valve 46 may be a three
way valve connected to pressurized air line 48 and three way valve 46
may be operated by means of pneumatic actuator 50 which is
2 1 92 1 38
connected to pressurized air line 52. Accordingly, after collecting tank
20 has been elevated to atmospheric pressure, three way valve 46 may
be moved to its second position and pressurized air may be fed from
air supply 70 pressurized via air line 48, through valve 46, through air
inlet port 42 into collecting tank 20 to assist in the draining of
collecting tank 20. In order to permit three way valve 46 to supply
atmospheric air to collecting tank 20, three way valve 46 may be
associated with a spring check valve 51 which is positioned in air feed
line 48 between air supply 70 and three way valve 46. When three way
valve is in the second position, atmospheric air may enter collecting
tank 20 through valve 46. When pressurized air is fed to spring check
valve 51 via feed line 48, spring check valve 51 is closed to the
atmosphere and pressurized air is fed via feed line 48 to collecting tank
20 . It will be appreciated that, in stead of first venting collecting tank
20 to the atmosphere, pressurized air may be fed to collecting tank 20 to
relieve the vacuum therein.
As shown in Figure 3, each of lines 38, 48 and 52 may be
supplied by a common source of pressurized air. Accordingly, each line
38, 48 and 52 may have an associated valve 53 so that each line may be
independently opened and closed.
In order to assist in monitoring the liquid levels i n
cyclonic separator 12 and collecting tank 20, sight glasses 60 and 62 may
be provided in the walls thereof. In order to assist in the operation of
the ~y~lem, switch 64 may be provided in cyclonic separator 12 and
switch 66 may be provided in collecting tank 20. Switches 64 and 66
may be connected to a controller 68. Controller 68 may also be
connected to air supply 70 which feeds air lines 38, 48 and 52. Switches
64 and 66 may be set at any desired position in cyclonic separator 12
and collecting tank 20 and, via controller 68 and air supply 70, may
actuate valves 34 and 46 depending upon the liquid level in cyclonic
separator 12 and collecting tank 20.
The operation of air/liquid separator 10 will now be
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described. When air/liquid separator 10 commences operation,
cyclonic separator 12 and collecting tank 20 are empty. The vacuum
source is then actuated, valve 46 is opened to open vent pipe 44 and
valve 36 is closed causing the pressure in cyclonic separator 12 and
5 collecting tank 20 to become sub-atmospheric. Valve 36 may be
manually moved to this position or, if a check valve is utilized, the
sub-atmospheric pressure in collecting tank 20 will cause the check
valve to close thus closing collecting tank 20. This permits a feed
stream to be drawn through inlet port 14 at a sufficient speed to cause
10 the liquid to rotate around inner wall 28 of cyclonic separator 12 thus
separating gaseous elements in the feed stream from the liquid
elements in the feed stream. The liquid elements will flow
downwardly through cyclonic separator 12, through outlet port 18,
through transfer pipe 26, through inlet port 22 into collecting tank 20.
As collecting tank 20 fills with liquid to a predetermined
level where switch 66 is positioned, switch 66, which may be a float
switch, is actuated. This sends a signal to controller 68 which causes air
to be fed via air feed line 38 to valve 34 to move valve 34 to the closed
position thereby preventing additional liquid from passing through
20 transfer pipe 26. It will be appreciated that the vacuum source is still
operating and accordingly the separated liquid will commence
accumulating in the bottom of cyclonic separator 12.
The actuation of switch 66 also causes controller 68 to send
a signal causing air to be fed through air feed line 52 to actuator 50 for
three way valve 46. When valve 46 is so actuated, vent pipe 44 is
closed thus completing the isolation of collecting tank 20 from cyclonic
separator 12. At this point, collecting tank 20 is still at sub-atmospheric
pressure. At this time, air is drawn through spring check valve 51,
through three way valve 46 into collecting tank 20 via air inlet port 42.
30 When collecting tank 20 reaches atmospheric pressure, valve 36 in
discharge line 40 opens permitting the accumulated liquid in collecting
tank 20 to be discharged. If valve 36 is a ball check valve, it will
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automatically open once atmospheric pressure is achieved in
collecting tank 20. Generally, the accumulated liquid will be sent to
further treatment, such as liquid/liquid separation techniques
generally known in the art.
After atmospheric pressure is reached in collecting tank
20, pressurized air may be fed via pressurized air line 48 closing spring
check valve 51. The pressurized air then travels via pressurized air
line 48, through three way valve 46 into collecting tank 20. The
pressurized air assists in expediting the drainage of collecting tank 20.
Switch 66 may include a programable delay timer. The
timer may be set for a predetermined time which is equivalent to the
amount of time required for the liquid to be drained or substantially
drained from collecting tank 20. After the predetermined time has
expired, switch 66 will therefore send a signal to controller 68.
Alternately, a second level indicator may be incorporated into
collecting tank 20 so as to actuate controller 68 when the tank has
drained or has substantially drained. Upon such a signal, controller 68
sends a signal to air supply 70 isolating collecting tank 20 from
pressurized air line 48, adjusting the position of three way valve 46 so
that collecting tank 20 may return to sub-atmospheric pressure and
opening valve 34 so that the liquid accumulated in the lower portion
of cyclonic separator 12 may drain into collecting tank 20.
Switch 64, which monitors the liquid level in cyclonic
separator 12, is also connected to controller 68. If cyclonic separator 62
is filling faster than collecting tank 20 can complete its draining cycle,
then switch 64 which may be a float switch, is actuated sending a signal
to controller 68 which will send a signal to prevent further liquid from
entering cyclonic separator 12. For example, controller 68 may send a
signal causing the vacuum source to shut down or may actuate a
signal (eg. a siren) to the workers to remove the nozzle from the work
surface. Alternately, cyclonic separator 12 may be connected to a second
collecting tank 20 (not shown) and on a signal from controller 68, the
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liquid in cyclonic separator 12 may be drained into such an additional
tank.
It will be appreciated that in a normal operation, the
system will operate on a continuous basis with a continuous source of
5 vacuum being exerted via inlet port 14. Further, by appropriately
sizing cyclonic separator 12 and collecting tank 20, the lower portion of
collecting tank 20 may be used as a holding tank to accumulate liquid
while collecting tank 20 is drained. The use of the pressurized air line
also assists in minimizing the required size of collecting tank 20 and,
10 therefore, the liquid hold up portion of cyclonic separator 12. It will be
appreciated that, as this equipment is generally used on a mobile
platform, the simplification of the apparatus, and the reduction in its
size, is highly advantageous.
It will be appreciated by those skilled in the art that
15 various changes and modifications may be made to the apparatus and
they are all within the scope of this invention. In particular, instead of
utilizing a three way valve for valve 46, three separate valves, each
operable between and open and a closed position, may be utilized, one
in vent pipe 44, one in pressurized air line 48 and one connected to
20 inlet port 42 to vent collecting tank 20 to the atmosphere.
