Note: Descriptions are shown in the official language in which they were submitted.
1065771
The present invention relates to gas separation and
more particularly to the removal of a liquid mist from a gas
stream.
Various types of gas separation apparatus are known
which use a scrubbing liquid to separate impurities from a gas
stream and as a result, a certain amount of the scrubbing liquid
becomes entrained in the form of a mist in the separated gas
stream. This scrubbing liquid must be eliminated from the gas
stream before the gas stream is discharged to equipment located
downstream of the separator apparatus or discharged to the
atmosphere because it may damage the downstream equipment or
pollute the atmosphere.
One type of known mist eliminator is formed by a :'
plurality of aligned narrowly spaced apart chevron-shaped baffles
' with correspondingly parallel chevron-shaped narrow passages
therebetween. Because of the shape of the baffles, this type of
mist eliminator baffle is commonly called a chevron eliminator
in the industry. Chevron eliminators function satisfactorily in
applications wherein the pressure drop across the eliminators is
relatively low. However, these chevron eliminators have a
propensity to become clogged with mud consisting of a residue of
particulate matter in the gas stream and the scrubbing~liquid in
applications wherein the pressure drop across the eliminators is
relatively high. As the mud builds'up in the narrow passages of ;~
~ the chevron baffle, the mist eliminating efficiency decreases.
`' When the efficiency drops to an unacceptable level, the chevron
mist eliminator vanes must be cleaned.
One way to clean these chevron eliminator baffles is to
shut down the entire separator apparatus and physically remove
~, 30 the chevron baffles for washing. This procedure is obviously ~-
t costly because of the cost of down time of the separator device
~ and further the cost of labor to remove, clean and replace the
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chevron baffles.
Alternatively, the chevron baffles can be cleaned while
remaining installed. This becomes necessary in very large
capacity separator installations because the mist eliminating
capacity of the chevron mist eliminator is a direct function of
its physical size. In large capacity separator installations,
therefore, the chevron eliminators reach a size which makes it
impractical if not impossible to remove them. However, cleaning
the chevron eliminator baffles while installed in a separator
apparatus has drawbacks. One way to ciean the baffles requires
that the separator apparatus be shut down so that workmen may
physically enter the separator to manually clean the mud from
the chevron baffles. Another way often employed is to place
nozzles adjacent to and downstream from the chevron eliminator
which nozzles periodically inject high energy cleaning fluid into
the passages between the chevron baffles. This can be done
without shutting down the separator apparatus. The drawback, of
course, is that the mud cleaned from the chevron baffles is -
reentrained in the clean gas stream downstream of the chevron
baffles, thus, recontaminating the cleaned gas stream.
Examples of chevron mist eliminator baffles used in
gas separator apparatus are shown in U.S. Patent No. 3,334,471, -~
issued on August 8, 1967 to Robert A. Herron, and U.S. Patent
'~ No. 3,624,696, issued on November 30, L971 to Irving Cohen and
Harold J. Byrne.
Another type of known mist eliminator is formed by a '~
series of staggered gas stream deflecting baffles forming a gas
, stream path. As the gas stream carrying a liquid mist traverses
.. .. .
the path, it impacts the baffles, thus, depositing the liquid
mist on one of the faces of the baffles. In addition, these
baffles change the direction of flow of the gas stream imparting
an angular acceleration to the mist carrying gas stream to
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1065771
centrifugalize residue liquid mist from the gas stream.
Some mist eliminator devices use planar baffles
projecting into the gas stream at an obtuse angle relative to
the general direction of the gas stream. This type of eliminator
functions well in applications wherein a relatively medium
pressure drop exists across the eliminator baffles. However, a
mud consisting of separated particulate matter and separated
liquid tends to build up on the baffles and it does not eliminate
enough of the liquid mist from the gas stream with the result that
the gas stream exiting from the eliminator device is still wet
when a medium wet gas stream is fed into it. When the gas stream
impacts the planar baffles, the liquid mist is deposited on the
impacted face of the baffle and the gas stream is turned in the ~ -
direction of the obtuse angle, thus, imparting a small angular
acceleration to the gas stream.
The liquid mist separated from the gas stream then
runs off the baffle and falls down into a reservoir. However,
when the liquid mist entrained in the gas stream impacts the
planar baffle, there is only a small amount of kinetic energy
transferred to the baffle from the liquid mist because the
baffle is rigid and not an efficient energy absorber. For this
. ~ . ~
reason, the liquid mist has an inclination to bounce off of the
baffle or splash back into the gas stream whereupon it is
reentrained in the gas stream. Additionally, because of the ,;
obtuse angle at which the planar baffles are disposed, the change ~ ;
in direction imparted to the gas stream, and, thus, the angular
acceleration induced thereby is relatively same and as a result,
the centrifugalizing effect is correspondingly small. An example `
of a gas separator using this type of obtusely disposed planar ,--
baffle is shown in U.S. Patent No. 2,491,545, issued on
December 20, 1949 to A. R. clark and James C. Buck.
Other mist eliminator devices use planar baffles
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projecting into the gas stream at a right angle to the general
direction of flow of the gas stream. This type of eliminator also
functions well in applications wherein a relatively medium pressure
drop exists across the eliminator baffles. However, a mud consist-
ing of separated particulate matter and separated liquid tends to
build up on the baffles, and it does not-eliminate enough of the
, liquid mist from the gas stream with the result that the gas stream
exiting from the eliminator devlce is still wet when a medium wet
gas stream is fed into it. When the gas stream carrying the
liquid mist impacts the planar baffles, the liquid mist is
deposited on the impacted face of the baffle and the gas stream
is turned in the direction of the right angle, thus, imparting
an angular acceleration to the gas stream. The liquid mist ~-
separated from the gas stream then runs off the baffle and falls
down into a reservoir. However, when the liquid mist entrained
in the gas stream impacts the baffle, there is only a small
amount of kinetic energy transferred to the baffle from the liquid
.: , 1 '
mist because the baffle is rigid and not an efficient energy
absorber. For this reason, the liquid mist has an inclination
to bounce off the baffle or splash back into the air stream
whereupon it is reentrained in the gas stream. Additionally, ~`
although these baffles disposed at a right angle to the gas stream
more radically change the direction of flow of the gas stream,
and, therefore, imparts a greater ~ngular acceleration to the gas
stream for a higher centrifugalizing effect than does the obtusely ¦~
disposed planar baffles, in doing so, the right angle planar
; baffles create large eddy currents at the impacted face of the
baffle which is counter productive to the job of eliminating
` liquid mist from the gas stream because these eddies pick up ¦-
;~ 30~ previously deposited liquid from the baffle reentraining the
liquid in the gas stream. An example of a gas separator using
this type of right angle disposed planar baffle is shown in U.S.
~.- . .
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-~ 1065771
Patent No . ~, 390, 400, issued on January 25, 1968 to Nils Dock.
Still other mist eliminator devices use planar baffles
projecting into the gas stream at an acute angle to the general
direction of flow of the gas stream. This type of eliminator
functions well at a slightly higher pressure drop across the
baffles than doe~ the previously mentioned eliminators. However,
it is about equally susceptable to mud build-up and also emits a -
wet gas stream when fed with a medium wet gas stream. As with
the obtusely disposed and right angle disposed baffies, when the
; 10 gas stream carrying the liquid mist impacts the planar baffles, -
the liquid mist is deposited on the impacted surface of the baffle ;
and the gas stream is turned in the direction of the obtuse angle, ~
thus, imparting an angular acceleration to the gas stream. The ; -
liquid mist separated from the gas stream then runs off the baffle
and falls down into a reservoir. Similarly, when the liquid mist
., ~ . .
entrained in the gas stream impacts the baffle, there is only a
small amount of kinetic energy transferred to the baffles from ' .
the liquid mist because the baffle is rigid and not an efficient
energy absorber. For this reason, the liquid mist has an
inclinatlon to bounce off the baffle or splash back into the air
stream whereupon it is reentrained in the gas stream. Further,
~, while these obtusely disposed baffles more radically change the
direction of flow of the gas stream, and, therefore, imparts a
'l greater angular acceLeration to the gas stream for a greater
centrifugalizing effect than either the obtusely disposed and ~-
right angle disposed planar baffles, it also creates iarger eddy -
~' currents at the impact face of the baffle. These eddies pick up ;
previously deposited liquid from the baffle reentraining the
liquid in the gas stream. Examples of separator devices using
3~ 30- these obtusely disposed mist eliminator baffles are shown in U.S.
Patent No. 2,379,795, issued on July 3, 1945 to Orrin E. Fenn;
U.S. Patent No. 3,710,551, issued on January 6, 1973 to John R.
-: , e
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1065'771
Sved, and U.S. Patent No. 3,738,627, issued on June 12, 1973 to
Ronald R. Scotchmur.
To overcome some of the adverse side effects of planar
baffles, such as the general inability to completely dry or
eliminate liquid mist from a medium wet gas stream, some mist
eliminators use curved baffles projecting into the gas stream
; and presents a concave surface to the gas stream. When the mist
carrying gas stream impacts the concave face of the baffle,
liquid mist is deposited on the impacted baffle face and the gas
stream is turned in the direction of the concave face, thus,
imparting an angular acceleration to the gas stream for
centrifugalizing residue liquid mist from the gas stream. The
use of curved mist eliminating baffles overcomes to a great
extent the problem of eddy currents caused by planar baffles.
However, because the curved baffles are rigid, and, therefore,
poor energy absorbers, the liquid mist removed impaction bounces
off or splashes back into the air stream whereupon it is
reentrained. Furthermore, this effects a better mist eliminating
action than is accomplished in the previously mentloned eliminator
devices employing planar baffles. An example of a gas separator
., ,
apparatus using a curved mist eliminating baffle is shown in U.S.
Patent No. 3,876,399, issued on April 8, 1975 to Joseph P. Saponaro.
The present invention recognizes the drawbacks of the
prior art mist eliminators and provides a solution which obviates
the problems of mud build-up on the separator members, eddy ,-
currents created when the direction of the gas stream is changed i~
and liquid mist bounce-off or splash as a result of mist impaction.
In addition, the present invention solves the problems encountered
by the prior art devices without producing a high pressure drop
across the eliminator baffles which requires a minimum amount of
energy to force the air stream through the eliminator device.
Further, the solution presented by the present invention
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10657'71
is straiyhtforward, inexpensive and practical to manufacture.
More particularly, the present invention provides a
mist eliminator device for separating a liquid mist from a gas
stream containing the liquid mist, the mist eliminator comprising:
a plurality of staggered baffles defining a sinuous path to be
followed by the gas stream containing the liquid mist to
centrifugalize the liquid mist from the gas stream, and, means
defining a sump in at least one of the baffles at a predetermined
location along the sinuous path for collecting the liquid mist `~
into a liquid poo~ removed from the gas stream and oriented so
that the gas stream containing the mist impacts the liquid pool ~:
to absorb the kinetic energy of the liquid mist contained in the
, gas stream.
Several advantageous embodiments of the present
invention are illustrated in the accompanying drawings, wherein
. like numerals refer to like parts throughout the several views,
and in which: -.
Figure 1 is a longitudinal cross-sectional view of one ~.
. preferred embodiment of a mist eliminator ~.
device of the present invention; ~.
Figure 2 is a cross-sectional view taken in the
direction of arrows 2-2 in Figure 1: ;-
Figure 3 is a longitudinal cross-sectional view of .
another preferred embodiment of a mist
`' eliminator device of the present invention; 1.
. Figure 4 is a longitudinal cross-sectional view of
.' another preferred embodiment of a mist
.~ eliminator device of the present invention;
Figure 5 is a longitudinal cross-sectiona} view of a
' 30 gas separator apparatus incorporating the mist
eliminator device of ~igure l; and,
.,~
; Figure 6 is a longitudinal cross-sectional view of
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1065771
another gas separator apparatus incorporating
the mist eliminator device of Figure 1.
Figure l illustrates a liquid mist eliminator device
comprising a plurality of staggered gas stream directing baffles
12, 14 and 16 which cooperate to define a sinuous path to be
followed by a gas stream containing a liquid mist which is to be
centrifugalized from the gas stream as it traverses the sinuous
path. For exemplary purposes, the staggered baffles 12, 14 and
16 are illustrated as being enclosed in and attached to the walls
of a housing 18. The housing 18 has a gas stream inlet 20
located proximate the upstream end of the sinuous path and a gas
stream outlet 22 located proximate the downstream end of the
', sinuous path. For the sake of clarity of understanding, the
general direction of flow of the gas stream from the upstream end '
to the downstream end of the sinuous path is defined by the - `
, ~ . . .
phantom line A-A. '
With continued reference to Figure 1, because the
incoming gas stream will first encounter the baffle 12 and then
the adjacently disposed baffle 14 as the gas stream traverses
the sinuous path, in relationship to each other the baffle 12 is
~- . .
an upstream baffle and the baffle 14 is a downstream baffle. The
upstream baffle 12 and the adjacent staggered downstream baffle
; 14 are shown as being arcuately shaped and generally concavely
', facing each other and, thus, toward the sinuous path formed
therebetween. I1:
`~ The upstream arcuate baffle 12 is illustrated as being
attached at its upstream edge 24 to one wall of the housing 18
and comprises a liquid trapping flange 26 projecting generally
~I~ radially from its downstream edge 28 into the gas stream L 30, advantageously at an angle of approximately 30 degrees to the
vertical. While the upstream arcuate baffle 12 is illustrated
as a segment having a constant radius extending through an arc of
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1065771
:~ .
approximately 90 degrees, it could extend through an arc of
greater or less than 90 degress depending upon the extent to
which it is desired to redirect the direction of flow of the gact
' stream. Further, the arcuate baffle 12 could follow a volute of
changing radius instead of the illustrated segment having a
constant radius.
The downstream arcuate baffle 14 is illustrated as
being attached to a wall of the housing 18 across from the wall
to which the upstream baffle 12 is attached and as being a
segment having a constant radius and extending through an arc
of approximately 180 degrees. However, the downstream baffle 14
i could extend through an arc greater or less than 180 degrees
' depending upon the extent to which it is desired to redirect the
: ,.
direction of flow of the gas stream. Further, the arcuate
baffle 14 could follow a volute of changing radius instead of
the illustrated segment having a constant radius. The downstream
~ arcuate baffle 14 comprises a liquid trapping flange 30
;; projecting generally radially from its downstream edge 32 into
~:, . .. .
the gas stream at an angle of approximately 30 degrees to the
~ 20 vertical and a sump, generally denoted as the numeral 34, formed
downstream of the upstream edge 36 of the baffle 14. The sump
?
`' 34, which is for collecting a pool 35 of liquid centrifugalized
from the gas stream, is preferably located immediately downstream
of the upstream edge 36 of the baffle 14 behind a weir flange 38
~ which projects generally radially into the gas stream from the
i upstream edge 36 of the baffle 14. It has been found in practice
that a one and a half inch high weir plate works well. The sump
34 is oriented so that the gas stream containing the liquid mist
redirected by the upstream baffle 12 impacts the liquid pool
30~ collected in the sump. To this end, the downstream edge 28 of
' the upstream baffle 12 and the upstream edge 36 of the downstream
baffle 14 overlap each other by a predetermined distance in the
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-` 1065~771
general direction of flow of the gas stream and are spaced apart
a predetermined distance in a direction transverse to the general
direction of flow of the gas stream.
With reference to Figure 2, the downstream arcuate
baffle 14 extends completely across the housing 18 between
opposite walls thereof and is attached at its opposite ends 40, .
42 to the walls of the housing 18. Thus, in this illustrated
... .
embodiment, the sump 34 is defined by the concave surface of the ~ .
downstream arcuate baffle 14, the weir flange 38, and the walls
of the housing 18 to the downstream arcuate baffle 14 is attached.
It should be obvious, however, that in the event the downstream
baffle 14 does not extend completely across the housing 18 so :
that the ends 40 and 42 of the baffle 14 terminate a distance
from the walls of the housing, that closure plates (not shown)
can be attached to the arcuate baffle 14 and weir flange 38 at ~
the ends. 40 and 42 of the baffle 14 to take the place of the :
. walls of the housing 18 in defining the sump 34.
. Returning to Figure 1, the downstream edge 28 of the
upstream baffle 12 and the upstream edge 36 of the downstream
baffle 14 cooperate to form, in essence, a nozzle through which
the gas stream flows. In practice, it has been observed that
best results are obtained when the cross-sectional area of this -
,
nozzle is greater than the cross-sectional area of the gas stream - ~
inlet 20. Likewise, another nozzle is formed between the .~ .
. downstream edge 32 of the baffle 14 and the downstream edge 28 ! ~ ~
of the upstream baffle 12. It has also been observed that best ~ ~.
results are obtained when .the cross-sectional area of this other
nozzle is greater than the cross-sectional area of the nozzle
. formed between the downstream edge 28 of baffle 12 and upstream 3
edge 36 of baffle 14. These observed results have been attributed ~`
~ to the fact that this construction approximates a diverging
`i nozzle which decreases the velocity of the gas stream moving
., '
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~065771
through it and decreases the pressure drop.
The baffle 16 is disposed downstream of the arcuate
baffle 14 and is illustrated as being planar. The planar baffle
16 is attached to the same wall of the housing 18 as is the
upstream arcuate baffle 12 and upwardly extends advantageously
into the gas stream at an obtuse angle of approximately 135
degrees to the vertical, thus, forming an obtuse angle to the
general direction of flow of the gas stream. The planar baffle
16 comprises a liquid trapping flange 44 projecting advantageously
from its downstream edge 46 at an angle of approximately 30
degrees to the vertical. While it is true that the planar baffle -
16 will cause more eddy currents than would an arcuate baffle,
the consequences of eddy currents at this most downstream baffle
16 are minimal because in most applications virtually all of the
liquid mist will have been removed from the gas stream before the
gas stream reaches the baffle 14. The planar shape of this
baffle 14 is merely a manufacturing expedient because a planar
3 baffle is easier to make than is an arcuate baffle. However, it ~ ,
;`. i9 foreseeable that in some applications, it may be desireable
to substitute an arcuately shaped baffle for the planar baffle 16.
, In operation, a gas stream containing a liquid mist,
j indicated by the arrows "A" enters the mist eliminator device
through the inlet 20 in a direction toward the upstream baffle 12.
~; The air stream impacts the baffle 12 which causes the air stream
to change its direction of flow. This change in flow direction
` imparts an angular acceleration to the gas stream centrifugalizing
a portion of the liquid mist. An additional amount of liquid
mist is separated out of the gas stream by impaction against the
' baffle 12. The liquid mist separated out of the gas stream by
impaction and by centrifugalizing runs along the concave surface
of the baffle 12 until it meets the liquid trapping flange 26.
The liquid trapping flange 26 acts as a dam and collects the
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- 1065771
separated liquid into a mass. The collected liquid continuously
- drains in solid streams, indicated by the arrows "B", from the
area upstream of the liquid trapping flange 26 downwardly into, ~ -
for example, a reservoir 48 formed in the bottom of the housing
18 below the inlet 20. Because this separated liquid falls in
the form of streams "s" of liquid rather than a mist or droplets,
very little, if any, liquid is reentrained in the gas stream "A".
The gas stream "A" next impinges upon the pool 35 of
previously separated liquid collected in the sump 34 formed in
the downstream baffle 14. Upon impact, the pool 35 absorbs the :~
. kinetic energy of a portion of the remaining liquid mist
entrained in the gas stream, thus, preventing the entrained liquid
mist from splashing off the downstream baffle 14 and into the
gas stream and at the same time collects a portion of the liquid
mist. As the pool 35 collects additional liquid, it overflows
the weir flange 38 and falls in the form of solid streams,
indicated by the arrows "C", downwardly into the reservoir 48. .
; Again, because this overfIowing liquid falls in the form of
coalesced liquid streams "C", rather than drops or mist, very
little, if any, liquid is reentrained in the gas stream "A". It
.~ should be noted that the surface of the pool 35 is at an angle
to the horizontal plane because of the air stream flowing over
it. This angle effectively increases the surface area of the
pool subjected to impact by the gas stream "A". Concurrently,
. ~ .
. the downstream arcuate baffle 14 again smoothly changes the
.,,
. direction of flow of the gas stream in the direction of the :
- arcuate baffle 14 thereby imparting an angular acceleration to
the gas stream centrifugalizing most of the residue liquid mist
.j ,
... from the gas stream. The residue liquid mist thus centrifugalized ~-
;, 30 flows along the concave surface of the arcuate baffle 14 under
, the influence of the gas stream until it meets the liquid trapping
flange 30. The liquid trapping flange 30 acts as a dam and
. . .
- 12 -
1065771
collects the separated residue liquid mist into a mass. The
collected residue liquid continuously drains in solid streams,
indicated by arrows "D", from the area immediately upstream of
the liquid trapping flange 30 downwardly into the reservoir 48.
Because this separated liquid falls in the form of coalesced
streams "D" rather than a mist or droplets, very little, if any,
liquid is reentrained in the gas stream "A".
After leaving the area of the downstream edge 32 of the
arcuate baffle 14, the gas stream "A" next impinges on the planar
surface of the planar baffle-16 whereupon the gas stream is again
caused to change direction to flow in the direction of the baffle
16 thereby imparting an angular acceleration to the gas stream
centrifugalizing residual liquid mist from the gas stream. Some
residual liquid mist is also separated from the gas stream by
impaction against the baffle 16. The separated-out liquid mist
flows along the planar baffle 16 until it meets the li~quid
trapping flange 44. The liquid trapping flange 44 acts as a dam
and collects the separated liquid mist into a mass. The collected
liquid continuously drains in coalesced streams, indicated by
arrows "E", from the area immediately upstream of the liquid
`~ trapping flange 44 downwardly into the reservoir 48. As
previously mentioned, because the liquid falls in the form of
coalesced streams "E" rather than a mist or droplets, very little,
if any, liquid is reentrained in the gas stream "A".
Upon leaving the downstream edge 46 of the baffle 16,
the now mist-free gas stream flows out of the mist separator
device through the outlet 22.
Accumulated liquid can be drained from the reservoir
.~ , i
48 through a conveniently located drain 50.
` 30 The flow of gas through the unit can be induced either
by a fan (not shown) located upstream of the inlet 20, or, more
conventionally, by a fan (not shown) located downstream of the
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- 1065771
outl~t 22.
~' :
Now referring to Figure 3, there is illustrated another ~-
advantageous embodiment of a mist eliminator device of the present
invention which is identical in every respect to the mist
eliminator device of Figure 1 except for the relative dispositions
of the downstream edge of the first upstream baffle and the
upstream edge 36 of the second downstream baffle. In the mist
eliminator device of ~igure 3, the downstream edge 28 of an
upstream arcuate baffle 12 and the upstream edge 36 of an
immediately adjacent staggered downstream baffle 14 overlap in
aligned relationship in the general direction of flow of the gas
stream. This configuration has utility in applications wherein
the velocity of the gas stream may be too low to propel the gas
stream across the space between the downstream edge of the
upstream baffle and the upstream edge of the downstream baffle
of the mist eliminator device of Figure 1 and follow the sinuous
path without dissipating somewhat before impacting the pool
collected in the sump. The nozzle.in the embodiment of Figure 3
formed between the downstream edge 28 of the upstream arcuate `- '
baffle 12 and the aligned upstream edge 36 of the downstream
"~ baffle 14 guides the gas'stream to a point closer to the pool 35
than does the configuration of Figure 1, thus, preventing
dissipation of the gas stream.
Turning now to Figure 4, there is illustrated another
advantageous emb,odiment of a mist eliminator of the present
invention which is identical in every respect to the mist
eliminator device of Figure 1 except for the relative dispositions
, of the downstream edge of the upstream arcuate baffle and upstream
edge of the downstream baffle. In the mist eliminator device of
Figure 4, the downstream edge 28 of an upstream arcuate baffle 12
and the upstream edge 36'of an immediately adjacent staggered
downstream baffle 14 overlap each other by a predetermined
- 14 -
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1065771
distanc~ in the ~eneral direction of flow of the gas strea~ and
also overlap each other a predetermined distance in a direction
transverse to the general direction of flow of the gas stream.
This configuration also has utility in applications wherein the
velocity of the gas stream may be too low to propel the gas
stream across the space between ~he downstream edge of baffle and
upstream edge of baffle of the mist eliminator device shown in
Figures 1 and 3 and follow the sinuous path without dissipating
somewhat before impacting the pool collected in the sump. The
nozzle in the embodiment of Figure 4 formed between the overlapping
downstream edge 28 and upstream edge 36 guides the gas stream
into the downstream arcuate baffle 14 to a point immediately over
~ , .
the surface of the pool 35, thus, preventing dissipation of the
~; gas stream.
: ;:
~ The mist eliminator device of the present invention can
;, be used to eliminate a liquid mist from a gas stream emanating
from virtually any source.
; For example, the mist eliminator device of the present
invention can be used in place of the chevron mist eliminator
baffles used in the devices disclosed of U.S. Patent ~os.
... .
3,334,471 and 3,624,696. Likewise, the mist eliminator devicè
... . .
' of the present invention can be used in the devices disclosed in , . .
U.S. Patent ~os. 2,373,330; 2,379,795; 2,491,645; 3,018,847;
` 3,390,400; 3,876,399; 3,710,551 and 3,738,627 in place of the
-~ mist eliminators disclosed therein.
, r,
`r: Figure S illustrates a gas separator apparatus S2
~` comprising the mist eliminator device of Figure 1 of the present
invention located downstream of an impurity removing means,
~` generally denoted as the numeral 54, which removes impurities
.. ~; ,
~;~ 30 entrained in a gas stream by contacting these impurities-with a
;~ scrubbing liquid.
The gas separator apparatus 52 is illustrated as
.
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:.: ,. , ~. , - :
1065~1
comprising a housing 118, enclosing bath, the mist eliminator
components and the impurity removing means 52. The housing 118
defines a dirty gas inlet chamber 56 having a dirty gas inlet 58
and a scrubbing liquid reservoir 148.
The impurity removing means 54 is in the form of a
stationary impeller section which comprises an S-shaped gas
stream directing wall 62 and an arcuate gas stream directing
wall 64 spaced from the S-shaped wall 62 to define a diverging
S-shaped gas stream passage therebetween which S-shaped passage
- ,
provides gas stream communication between the dirty gas inlet
chamber 56 and mist eliminator device or section 10. The lower
edge of the arcuate wall 62 extends downwardly into the reservoir
i 158 below the level of the scrubbing liquid contained therein
when a dirty gas stream is flowing through the S-shaped passage.
The scrubbing liquid reservoir 60 comprises a drain
150 for draining dirty scrubbing liquid and particulate
contaminants separated from the gas stream, and scrubbing liquid
replenishing means (not shown) for'replenishing the scrubbing
liquid as required to maintain the proper level in the reservoir.
In operation, dirty gas from the dirty gas inlet
~ chamber 56 enters the S-shaped passage sweeping the scrubbing
i~ liquid from the reservoir with it into the S-shaped passage
~; as indicated by the arrows "F". The scrubbing liquid, together
with the particulate contaminants contained in the gas stream, is
subjected to extremely intense centrifugal action as it traverses
~` the S-shaped passage. As a result, the scrubbing liquid collects
,~ into a stream moving along the S-shaped passage and the particulates
are deposited in this sheet of scrubbing liquid, and are, thus,
removed from the gas stream. This stream of scrubbing liquid and
30- deposited particulates is discharged from the exit of the S-shaped
passage generally downwardly into the scrubbing liquid contained
~` in the reservoir 148 as indicated by the arrows "G". The gas
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`- 1065771
stream, now substantially cleaned of particulate matter, exiting
the S-shaped passage has a mist of entrained scrubbing liquid.
This gas stream containing the scrubbing liquid mist flows toward
the upstream arcuate baffle 12 of the mist eliminator device as
indicated by the arrows "A" and the process as described in
reference to Figure 1 for eliminating the entrained liquid mist
occurs.
Figure 6 illustrates another gas separator-apparatus
152 comprising the mist eliminator device of Figure 1 of the
present invention located downstream of an impurity removing
means, generally denoted as the numeral 154, which removes
impurities entrained in a gas stream by contacting these impurities
with a scrubbing liquid.
The impurity removing means 154 comprising a flow
, through housing 156 having a dirty gas inlet 158 at one end and
a clean gas outlet 160 at the other end. The clean gas outlet
; 160 is in fluid communication with the gas stream inlet 20 of the
mist eliminator by means of, for example, duct 162.
A dirty gas stream enters the housing 156 and passes
through a first restraining grid 164 extending across one
extremity of the housing 156. The dirty gas stream then passes
into contact zone 166 where it contacts gas contact elements 168,
which advantageously are substantially spherical in shape. The
spherical elements 168 are coated with a thin film of scrubbing
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liquid from either treating fluid inlets 170 or nozzles 172 or
both. Upon contacting the spherical elements 168, the dirty gas ';
is cleaned since the thin film of scrubbing liquid coating thereon
either causes particulate matter to adhere thereto, or,
alternatively, chemically reacts with the impurities in the gas
stream. The spherical elements 168 are buoyed upwardly toward a 1`
second restraining grid 174 which is positioned to direct the
clean gas stream out of the contact zone 166, and direct the
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10657'71
spherical elements 168 out of the cleaned gas stream. The
spherical elements 168 fall by gravity into element treating zone
176 which is formed by baffle means 178 dividing a portion of the
housing 156 between the first and second restraining grids into
the contact zone 166 and the element treating zone 176 for
recirculation back into the contact zone 166. The substantially
spherical elements 168 continue to fall downwardly in the element
treating zone 176 past the scrubbing fluid inlet 170, which is
emitting a scrubbing liquid, until they reach the lower portion
of the zone 176. At the lower portion of the element treating
zone 176, there exists an exit aperture 180. Directly below exit
; 24 is the first restraining grid 164 having integral therewith a
fluid impervious portion 182. The fluid impervious portion 182
prevents the dirty gas stream from overcoming the force exerted
by the scrubbing liquid from fluid inlet 170 on the spherical
``i elements 168, and forcing them upwardly in the element treating .; .
,; zone 176.
The scrubbing liquid fro~ fluid inlet 170 cleans the
spherical elements 168 leaving them coated with a thin film of
. .
the scrubbing liquid, and recirculates them again into the dirty
, gas stream. The scrubbing liquid from liquid inlet 170 as well
as the scrubbing liquid from nozzle 172 drains downwardly and is
collected in reservoir 184 of the housing 156, from which it may
be withdrawn through drain 186.
The scrubbing liquid emitting from nozzle 172 may be a
,; different liquid than that emitting from inlet 170. For example,
~. .
`.~ in the removal of sulfur dioxide, it may be desireable to
formulate a liquid to be introduced through nozzle 172 which
contains a high concentration of calcium carbonate, with a view
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~ 30 - toward reacting the calcium carbonate chemically with the S02 of
... . .
` the dirty gàs to form calcium sulfate. The calcium sulfate is a, .. - ,
~ solid which can be flushed from the spherical elements 168 by a
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` 10657 71
spray of water from treating fluid inlet 170. The impurity
removing means 154 is more fully described in U.S. Patent No.
3,810,348, issued on May 14, 1974 to Thomas W. Byers et al.
The cleaned gas stream exiting the contact zone 166
through the restraining grid 174 has an entrained mist of
scrubbing liquid. The cleaned gas stream with the entrained mist
of scrubbing liquid exits the housing 156 via outlet 160 and flows
through the duct 162 and into the inlet 20 of the mist eliminator
device as indicated by arrows "A". The process of mist
elimination then follows as described in relationship to Figure 1
and a cleaned gas stream absent any scrubbing liquid mist exits
from the mist eliminator through outlet 22.
The foregoing detailed descriptions are given primarily
for clarity of understanding and no unnecessary limitations
should be understood therefrom, for modifications will be obvious
to those skilled in the art upon reading this disclosure and may
,. ~
~ be made without departing from the spirit of the invention or
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` the scope of the appended claims. .
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