Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FIEI,D OF TH~ VENTION
This invention relates to gas-liquid separators.
BACKGROUND OF THE INVENTION
The presence of gas or air bubbles in most systems
employing flowing liquids is highly undesirable. A particular
system of this category is a closed hot water heating system
in which the gas, in the form of air bubbles flowing with
the water, significantly reduces the efficiency of the
system. For example, large commercial buildings generally
operate on a border line near the upper limits of what is
referred to as a critical condition where there is a need to
operate a boiler at a higher temperature than would be re~uired ~`
if the gas were not present in the system in order to off-set
cold areas resulting from poor liquid circulation and heat
exchange. Most buildings as a result of poor design layout
of the circuits have particular areas which act as air traps
and affect the circulation throughout the entire building. `
Furthermore, because oxygen is one of the prime causes of
rapid corrosion, the air bubbles produce extreme corrosion
build-ups at one or more locations along the circuit which
provide undesirable restrictions in the pipelines.
The heat exchange properties of the system are
dependent on the cleanliness or purity of the water in the
system. Most of the elements common to the water can be
controlled by chemicals to reduce the rate of corrosive
attack. However, the oxygen is the most prominent promoter
of electro-chemical activity and therefore, should be
reduced or removed from the system.
To further enhance the difficulty, heat when directed
at a water containing conduit, will bring about a release of
1 gas bubbles in the flowing medium. These bubbles are in the
form of steam and other gases which generally do not condense
back to a liquid form although this is dependent on the
weight of the converted liquid and the operating temperature
which is usually sufficiently high throughout the entire
circuit to maintain the gaseous bubbles. The gas behaves
in:the same manner as does the air in the system in terms of
flow restriction, reduced heat transfer and corrosive
activity.
The corrosion itself is primarily an electro-
chemical action which includes the removal of metal from
one point in the pipe system ~d the depositing of the metal
along other points of the system. The loss of metal from
the first point ultimately results in ruptures of leakages.
~he deposit at other points results in progressive build- -
ups and ultimate blockages. Again oxygen is the most
prominent agent resulting in the corrosion and should
therefore be eliminated as much as possible from the flow.
Most systems include local air venting means, however,
these are only effective against trapped air and are not
effective against the air bubbles which are actually flowing
with the water. Therefore, such venting only occurs after
there has been a total air blockage in the system and in
cases where the amount of air in the system is not sufficient
to close off an area, its detrimental effects may not be
appreciated although they do exist. This results in unrealized
wastage of fuel and poor heat transfer conditions relative
to a system in which air is not present.
The air in the system also produces hardships on
the pumping means by reducing flow velocity and continuity.
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l From the one end of the system the pump is attempting to
force the weight of the water up and over the highest
point in the system and from the other end of this system
the pump is attempting to pull the water downwardly with
the assistance of gravity. However, such pushing and
pulling is adversely effected by the stretching of the air
in the water. In an air-free circuit the water behaves
as an interlocked chain and experiences no such stretching
effect. However, this condition rarely exists in practice.
Attempts have been made in the past to provide
air gas separators such as that described in Canadian Patent
965,357, issued April lstl 1975. However, these attempts
are based on providing a vortex in the fluid passing through
the separator to throw the heavier water to the outside as
a vortex, thereby separating the gas from the liquid.
However, due to the unpredictability of air bubble behavior
in a flowing liquid medium such vortex systems are very
difficult to control. They are dependent upon flow speeds
and vortex force. For instance a vortex separator will
not work where the flow speed is not high enough to provide
a sufficiently strong vortex to throw the water to the out-
side. Nor will it work if the flow speed is excessively
high because the air bubbles, which may be microscopic in
size, do not flow with the liquid medium at flow speeds
`~25 beyond a certain rate. Therefore, vortex separators have
very definite limitations.
The present invention overcomes the above diffi-
culties by providing an anti-vortex gas-liquid separator
which is compartmentalized for stabilizing the liquid flow
and eliminating high speed streams of gas-carrying liquid
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l for purposes of slowing the liquid flow to the extent that
the density effect of the air bubbles in the water provides
a natural separation of the gas from the liquid.
The separator comprises an inlet passage opening
into a first compartment of increased volume for reducing
liquid flow speed. Provided in the first compartment is
an impact surface for providing a back pressure on liquid
flowing from the inlet passage and for reversing the liquid
flow direction. Anti-vortex means is provided for impeding
the liquid flow path and for suppressing flow vortex resulting
from the reversal in liquid flow direction. The separator
includes a second compartment of increased volume for a
stable, slow uniform flow of stream-free liquid. The second
compartment is separated from the first compartment by the
anti-vortex means. A venting outlet for the escape of the
separated gas and a liquid outlet in the second compartment
for the outflow of gas-free liquid are also provided.
BRIEF DESCRIPTION OF T~E DRAWINGS
Other features of the present invention w~ill also
become apparent from the following detailed description of
the preferred emhodiments according to this invention, wherein:
Figure 1 is a sectional view taken through a first
arrangement of an air liquid separator according to this
invention;
Figure 2 is a sectional view taken along the lines
of 2-2 of Figure l;
Figure 3 is a sectional view taken along the lines
3-3 of Figure l;
Figure 4 is a sectional view taken through a second
arrangement of an air liquid separator according to this
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1 invention;
Figure 5 is a sectional view taken along the lines
5-5 of ~igure 4;
Figure 6 is a sectional view taken along the lines
6-6 of Figure 4;
Figure 7 is a sectional view looking down on a
third arrangement of an air liquid separator according to
this invention; and
Figure 8 is a sectional view of a similar model
10 slightly modified from that shown in Figure 7.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIM~NTS
ACCORDING TO T~IIS INVENTION -
:
Figures 1 through 3 show a gas-liquid separator unit
comprising an end por,tion 3 and a cannister 1 removably
secured to the end portion. This particular unit may be
15 inserted directly in the pipeline or as a by-pass of a
closed hot water heating system. The water flowing through
the system enters the separator through orifice 5 on the
positive side of the separator or the side from which the
water is being pushed into the separator. This water contain-
20 ing trapped air bubbles is forced at high speed through extended
inlet piping 7 in the direction of arrows 8. Provided at
the interior end of piping 7 is an outwardly funnelled portion
9 from which the water flows into first compartment 10 of
increased volume relative to the inlet piping. It should
25 also be noted that the funnelled end 9 of piping 7 is also
increased in volume relative to the inlet piping.
Screen guiding means 13 is wrapped about the piping
and its funnelled end and extends the length of cannister 1.
The screen guiding means consists of layers of screening
30 material wrapped a~out one another.
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1 Anti-vortex means 15 which is preferably of wool
mesh material is provided in the screen guiding means directly
in the path of the liquid flowing from the inlet piping.
A second anti-vortex means 19 which is constructed
from the same material as anti-vortex means 15 divides the
cannister to provide a second compartment 21. The venting
outlet 18 for the escape of separated gas is provided in
the first compartment while the liquid flow outlet 23 is
provided in the second compartment. Water flowing from the
separator flows out exit port 25 which is provided on the
suction side of the pump.
Also provided in the second compartment is a
third anti-vortex wool mesh 20 wrapped about the outer
surface of the inlet piping in the screen guiding means.
The separator unit of Figure 1 is inserted verti-
cally in a pipeline as shown in the drawings with the first ;~
compartment being located above the second compartment. It
will be noted that the upper end of liquid outlet 23 is
spaced from the bottom of the second compartment.
The principle of operation of the separator according ;~
to the present invention is to stabilize the liquid flow to
the extent that there is a tranquil uniform flow of greatly
reduced speed such that the relative densities of the
air bubbles and the water become the dominant factors and
permit the releasing of the air bubbles in an upward direction
from the water and through the escape vent 18. This prin-
ciple of operation is fulfilled by forcing the water carrying
the bubbles at high speed through the inlet port 5 and up
piping 7 which imparts an upward velocity to the air
bubbles. As the water leaves the funnelled end 9 of the
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1 piping, it is subjected to a compartment of substantially
increased volume which in combination with the weight of the
water, reduces the liquid flow speed while the air bubbles
continue their rapid upward travel. At the same time, part
of the flow is directed outwardly at the screen guiding
means which encourages the air or gas bub~les to unite
when they come into contact with its coarse surface. Bubble
uniting and consequent enlargement occurs when the bubbles
contact one another due to the flow resonance as affected
by the abrasive action of the coarse screen surface. In
addition, the layering of the screen means form flow tubes
for the upward travel of the entrapped bubbles to the
venting outlet. Therefore, as the water easily passes through
a large surface area of the screen into the enlarged,
relatively complacent compartment 10, the air bubbles are
trapped in the screening due to its filtering and guiding
action. Furthermore, the screen acts as an abrasive against "
any possible flow vortex within its confines resulting from
the outward funnelling at the outlet end of the inlet piping.
The central flow passing from the inlet piping which
is not subjected to the screen guiding means moves along a
more vertical path and is forced through wool mesh 15. This
wool mesh also acts as an anti-vortex means and impedes the
flow path of the liquid to further reduce the flow speed.
Again the abrasive surface of the wool mesh acts as an air
bubble filter in which the microscopic bubbles unite to
form larger bubbles.
Liquid flowing through the wool mesh continues its
upward travel until it impacts against the end 17 of the
cannister. This impact surface further enhances the tendancy
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1 of the bubbles to unite and in combination with the wool
mesh provides a back pressure on the liquid flowing from
the inlet piping.
After the liquid has impacted against end surface
S 17 or any trapped liquid providing the bac~ pressure, the
liquid flow direction is reversed. However, at this point,
the liquid is moving so slowly that the air bubbles separate
because they are much lighter than the water and they con-
tinue their upward movement within the screen guiding means
to the escape vent.
As the essentially bubble-free water moves downwardly -
under its own weight and through the suction of the pump,
it passes through anti-vortex wool mesh 19 into the second
enlarged compartment 21. The anti-vortex wool mesh acts as
an insurance against any possible entrance of air bubbles
into the second compartment and essentially eliminates all
turbulences and streaming in the flow patters so that the
water in the second compartment moves at a slow uniform speed
and flows outwardly through the liquid outlfow 23 and the outlet ~`;port 25 to the system pipes. It should be noted that the
anti-vortex mesh 19 is located such that water flowing out
of the inlet passage cannot enter directly into the second
compartment.
The provision of third anti-vortex wool mesh 20
stabilizes any upward flow of water along the sides of the
inlet passage which might otherwise initiate streaming in
the second compartment.
I The positioning of the liquid outlet spaced from
0 the bottom of the second compartment prevents any slag,
`~, 30 which has settled on the bottom of the separator, from
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1 escaping with the bubble-free liquid. When it becomes
necessary, the unit can be easily disassembled to remove
the collected slag.
Figures 4 through 6 show a second separator unit
arrangement consisting of an end portion 30 and a cannister
32 removably secured to the end por~ion and housing the
internal elements of the separator. In this arrangement,
the unit is inserted directly in the system or as a by-pass
with the cannister being located in the downwardly extending
position.
Housed within cannister 32 is inlet piping 36
opening into divided cup 40. The inlet piping and cup are
again surrounded by layers of screen material 44. Provided
in the screen guide, wrapped around the outer surface of the
inlet pipe above the cup, is wool mesh 46. Located directly
below the cup in the screen guide is wool mesh 54. A third
wool mesh 50 divides the cannister into first compartment
48 and second compartment 52 of increased volume relative to
the inlet pipe. Liquid flow outlet 56 spaced from the bottom
of the cannister is provided in the second compartment and
gas bubble vent 55 is provided in the first compartment.
The principle of operation of this unit is identical
to that described with respect to Figures 1 through 3, i.e.,
to stabiliæe and eliminate high speed liquid flow and any
streaming or turbulence in the liquid flow.
The bubble-carrying liquid flows at high speeds
through inlet port 34 and down inlet passage 36 into cup 40
where it impacts against the base 42 of the cup. The liquid
flow direction is reversed upwardly within the screen guide
44 which acts as both a bubble filter for water escaping
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1 through the screen and as a means for suppressing any
flow vortex resulting from the reversal of flow direction.
It should be noted that wool mesh 50 is positioned to pre-
clude water flowing directly from the cup into the second com-
partment 52 without passing through the wool mesh.
The water which does not escape through the screen
guide is forced upwardly to wool mesh 46 impeding the liquid
flow path and reducing the liquid flow speed. Wool mesh
46 essentially eliminates all vortexing within the screen
guide and again acts a bubble collector and ur.iter. As the
water flows through the screen it is essentially bubble free
with the separated bubbles being trapped within the screen
guide where they are united to form bubbles significantly
larger than those carried into the unit with the liquid flow.
The weight of the water carries it downwardly in uniform slow
motion through wool mesh 20 and into the second compartment
52 while the air bubbles, wh;ich have been imparted with a
high velocity upwardly often impacting the base of the cup,
climb quickly to escape through vent 55. Wool mesh 50
eliminates essentially all streaming and turbulence of the
liquid in the second compartment. The bubble-free liquid
then flows through outlet 56 and out port 58 provided on
the suction side of the pump. It should be noted that outflow
56 is spaced from the bottom of the cannister such that slag
settling in the cannister is trapped and will not flow
through the separator. The cannister can then be removed
for cleaning purposes. In addition, this unit is particularly
useful as a pot feeder or inserting chemicals directly into
the pipeline.
Wool mesh 54 provided in the screen guide at the
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1 base of the cup stabilizes any upward pull which might other-
wise initiate streaming in the second compartment.
The gas-liquid separators shown in Figures 7 and
8, are constructed such that they are effective for direct
installation in a closed pipe system regardless of their
direction of installation. This is an important feature of
these particular units because it is often difficult to
determine flow direction in a blocked zone. Furthermore,
when the system is shut down, as required during installation,
~ 10 there is no indication as to the direction in which the water
; is flowing.
Each of the units shown in Figures 7 and 8 are
compartmentalized and include means for slowing fluid flow
and eliminating streaming within the fluid flow so that
, 15 their principle of operation is identical to the above-
described units.
i The separator shown in Figure 7 can be installed
in a hot water heating system with the water flowing in
eigher a left to right or a right to left direction and
effective in both cases. In a situation where there is
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right to left flow the unit operates as follows: water is
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forced through inlet port 62 by the pump and out the funnelled
end 66 of inlet piping 64. The area between the end wall 70
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of the separator and the funnelled end of the inlet piping
forms a first compartment generally indicated at 67 divided
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;~ from second compartment 72 by wool mesh 68.
i The flow speed of the gas-carrying liquid is reduced
at the funnelled end of the inlet piping as a result of the
; increase in volume in compartment 67. The liquid is imme-
~ 30 diately subjected to wool mesh 68 which acts as a bubble
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1 filter and an anti-vortex to liquid flowing from the fun-
nelled end 66. It is also positioned directly in the liquid
flow path.
The liquid flowing through the wool mesh immediately
impacts against the end wall 70 and the flow direction is
reversed back into the separator such that the liquid once
again passes through the wool mesh prior to entering second
compartment 72. Both the wool mesh and the end wall provides
a back pressure to liquid flowing from the inlet piping.
The flow of the liquid through the wool mesh in
both directions and the impacting of the liquid on the end
wall of the separator tends to unite and collect essentially .
all of the gas bubbles carried in the liquid. These bubbles
are guided upwardly through the mesh to the venting means
which cannot be seen in Figure 7 but which is identical to
that shown in Figure 8. The liquid flowing in second com-
partment 72 of substantially increased volume is moving
at a slow uniform speed without streaming or turbulence.
From the second compartment the fluid must flow
through a further wool mesh 74 to the outflow 76 and the gas-
free liquid then flows out port 78 on the suction side of the
separator.
As can be seen from the drawings, ports 62 and 78
are located centrally of the separator and if the separator
were reversed or the direction of liquid flow were left
to right, the unit would still be effective with wool mesh
74 providing the impedance between the first and second
compartments and end wall 60 providing the impact surface
for uniting bubbles and reversing the flow direction.
The unit shown in Figure 8 is basically the same as
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1 that shown in Figure 7 with the exception that compartments
84 and 86 are provided adjacent respective end walls 83 and
85 of the separator and additional wool meshes 88 and 90
are provided to divide the enlarged interior compartment
into sub-compartments. The provision of venting outlet 80
an concave roof 81 are provided in the enlarged interior
sub-compartment which is consistent in both the units -shown
in Figures 7 and 8. The particular shape of the roof of this
separator provides even greater volume in the interior
compartment to assure a more reduced liquid flow and to
provide a bubble trap form which the separated gas is
directed to the venting outlet.
Another advantageous feature of the~separator
shown in Figures 7 and 8, is that it can be used a gas-
liquid separator for separating liquid from a flowing gaseous
medium by simply placing it upside-down such that the liquid
trapped by the wool mesh flows out the escape vent.
The size of all of the units described above is
completely variable although a highly critical feature is
the provision of a volume increase in the interior of the
separator to assure a relative slowing of the liquid flow
pattern. Therefore, the unit can be made in a very compact
model which is especially useful for installation directly
into a pipe system and capable of handling flow rates
within the system or it can be made into a much larger unit
capable of handling much higher flow rates.
Although various preferred embodiments of the
invention have been described herein in detail, it will be
appreciated by one skilled in the art that variations can be
made thereto without departing from the spirit of the inven-
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1 tion or the scope of the appended claims.. ~
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