CA1106777A - Removal of undesired components from gases - Google Patents
Removal of undesired components from gasesInfo
- Publication number
- CA1106777A CA1106777A CA301,418A CA301418A CA1106777A CA 1106777 A CA1106777 A CA 1106777A CA 301418 A CA301418 A CA 301418A CA 1106777 A CA1106777 A CA 1106777A
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- CA
- Canada
- Prior art keywords
- gas
- bodies
- mist
- flow
- baffles
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/10—Particle separators, e.g. dust precipitators, using filter plates, sheets or pads having plane surfaces
- B01D46/12—Particle separators, e.g. dust precipitators, using filter plates, sheets or pads having plane surfaces in multiple arrangements
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Gas Separation By Absorption (AREA)
- Separation Of Particles Using Liquids (AREA)
- Filtering Of Dispersed Particles In Gases (AREA)
- Separating Particles In Gases By Inertia (AREA)
- Treating Waste Gases (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A gas scrubber and/or mist eliminator for high-velocity gas in the range between about 1,000 to 2,500 feet per minute.
The gas flows horizontally through a duct or conduit in which a plurality of generally vertical, high voidage, fibrous, non-capillary, free-draining bodies are interposed. The gas both passes through and is deflected by the bodies and its mist and/or other components are captured and drained by the bodies. Re-entrainment of the drained liquid flowing out of the bodies is prevented. The bodies may be arrays of rows of separate baffles or they may be mounted on vanes.
A gas scrubber and/or mist eliminator for high-velocity gas in the range between about 1,000 to 2,500 feet per minute.
The gas flows horizontally through a duct or conduit in which a plurality of generally vertical, high voidage, fibrous, non-capillary, free-draining bodies are interposed. The gas both passes through and is deflected by the bodies and its mist and/or other components are captured and drained by the bodies. Re-entrainment of the drained liquid flowing out of the bodies is prevented. The bodies may be arrays of rows of separate baffles or they may be mounted on vanes.
Description
7~
B~CKGROUND OF THE INVF.NTION
This invention relates to the removal ~f undesired componen-ts from Eluids and has par-ticular rela-tionship to such removal where the fluids flow at high velocities be-tween abou-t 1,000 to 2,500 feet per minute. While in the interest of being concrete in dealing with the details of this invention, this applica-tion concerns itself with the removal of undesired com-ponents from gas, it is also applicable, in its broader aspec-ts, to the removal oE unaesired components from liquids, To the extent that this invention is so applicable to liquids, such application is within the scope of this invention~ The components which are removed from a gas may be soluble such as soluble salts or acids, for example acetic, nitric or hydrochloric acid, or insoluble particulate such as sulfur, carbon powder, fly ash or graphite. The components may also be mis-t, either initially present or deliberately, injected into the gas to dissolve sol-uble particulates and to wet and wash down insoluble particulate.
Essentially, this invention serves for gas scrubbing and/or mist elimination for high velocity gas flow, ~O Separation and removal of undesirable or contaminant particulates from a gas stream in accordance with the teachings of the prior art has been effected by two principal methods: gas filtering and centrifugal force separation. Gas filters are comprised of porous, foraminous or fibrous media, woven or non-woven through which the gas is wholly conduc-ted. Fil-ters sep-arate by means of inertial impaction and impingement of the par-ticles on the ~Eibers as the gas containing -the particles passes through the fil-ters~
~ ' For removal of small particle sizes, the fibers must be fine.
~hile gas filters are reasonably effective in particulate removal, the gas velocity through a filter must be main-tained at relatively low levels to avoid excessive and unecono-mic gas pressure drops. This is particularly true in the case of fine particulate filtration, where the particles are in the 1-20 micron size range and the fibers are very fine, typically in the 10 to 200 micron range. Gas pressure drop through a fib-rous filter is approximately proportional to the square of velocity of the gas in the -turbulent flow regime. Industrial fine particulate filters, such as baghouses, consequently have very large filter surfaces, operating typically at 5 to ~0 feet per minute gas face velocity, and are relatively expensive. Further, the optimum ranges of gas velocity through the filter media with respect to the efficiency of particle removal by the mechanisms of interception and impac-tion are invariably higher than those which can be practically and economically employed with respect to the gas pressure drop across the filter.
While fibrous or filamentary woven or felted gas filter media are applicable to particulate removal, including mist filtration, they do not readily lend themselves to continuous washing in the case of solid particulate removal or to too high liquid loads in the case of mist removal alone.
- Because of the uniformity and small size of the fluid passages through such filter media, and the competition of liquid and gas flow for these fluid flow passages, the flow capacity of the filter for gas is restricted because of the presence of liquid, or that for liquid because of the presence of the gas.
If a filter medium is used which possesses even a moderate degree of dynamic capillarity, under a specific combination of gas and liquid loadings, liquid is retained and gas flow t '~fi ~ ~ ~
choked off except at extremely hlgh gas-pressure drops.
Dynamic capillarity~ or the equivalent dynamic liquid hold-up in a medium, is the tendency to retain liquid in the pores o~ a medium~ which exists under flow conditions of the gas and the dynamic loading rate by such flow of the medium with liquid. The capillarity effect is enhanced by the continuous inaection of liquid by the flowing gas into the medium. In the case of static capillarity, the only force counteracting the capillary force is gravity. In the case of dynamic capillarity, the capillary force is counteracted in addition by the force exerted by the gas and augmented by the continuous loading of liquid. The effect of appreciable liquid loadings on such capillary filter media resulting from dynamic capillarity is to make the media behave as a virtually solid wall with respect to gas flow.
For dynamic liquid loads, such as are generated by filter washing~ even a small degree of capillarity yields significant gas flow passage closure with liquid. Additionally, if the gas stream contains solid insoluble particulates, capillary filter media are highly susceptible to solid plugging.
Rebours, U. S. 3,733,789, which is typical of the prior-art of this type, uses a sprayed tubular filter cloth to form a continuous stable film of washing liquor on the cloth through which the gas is "microsieved." Rebours' data on gas-flow resistance as a function of linear gas velocity illustrates the typically high-resistance/low-flow character-istics of the capillary filter media, whether woven cloth or compacted or felted fibrous material. Rebours' teaching is specific :for liquid "micromists" and as pointed out by Rebours, solid insoluble particles unfailingly clog the filter after a few hours of operation.
Fairs U. S. 3,135,592 also discloses an irrigated filter medium but in countercurrent liquid-gas flow. Fairs' gas velocities are about 15 feet per minute and fall into Rebours' range of 4 to 20 feet per minute representing essentially laminar, as distinct from turbulent flow, gas flow. Rebours and Fairs are limited to such low gas velocities because the ~as-flow passages are clogged with liquid. Sprayed screen devices such as those of Alliger, U. S. 3,7~3,~34, and Mare, U. S. 3,785,127, suffer from the same gas flow limitations result-ing from the necessity of trying to force both liquid and gas through uniform-opening restricted and/or capillary flow space in a filter medium. Lucas U. S. 3,370,LlOl, discloses a teaching similar to that of Fairs, except that the fibrous filter medium is deliberately operated in the flooded condition.
Centrifugal-force separators, such as devices with parallel-vane serpentine or sinusoidal-paths, or chevron or zig-zag passages, are used primarily for mist elimination, in clean gases not containing solid particulate. Such parallel vane separators are commonly used for removing liquid carryover in steam boilers, water-cooling towers, and in gas-liquid contacting apparatus such as distillation or fractionation towers, evaporators, gas-scrubbing apparatus and the like. Another area of application is the removal of mists from the air intakes of power turbines such as marine-power or propulsion plants. In such separators the fluids carrying the suspended matter is bent or deflected by the vanes and the suspended matter is eJected by centrifugal force. The force exerted on a particle of mass M is Mv , where v is the velocity of the particle and r the radius of the path. It is desirable that v should be high or r small.
Centrifugal-force impaction separators operate at much higher velocities than do ~ilter media, and are used for low-load liquid mist removal or for batch particulate removal.
In ~ig-zag sinusoidal-passage para:Llel-planar types of separators, the removed liquid must drain under the influence of gravity without accumulating wi~hin the passages or being otherwise subject to reentrainment in the gas. Liquid occur-ring either as a mist~ or as a delLberately-introduced spray wash that has been removed and col:Lected as drops or as a liquid film on surfaces exposed to the flowing gas, is sub-ject to being dragged along in the direction of gas flow by gas friction and momentum transfer. The resulting liquid carrythrough or reentrainment lowers the overall liquid removal efficiency. Various expedients have been suggested to overcome this deficiency. Hosch, U.~. 1,616,802, describes a serpentine-passage separator having liquid-collection baf~les protruding from the peaks of the corrugations. Other modi-fications of the sinusoidal or zig-zag-path vane separators are typically shown by Clark, U.S. 2~802,543, Sokolowski, U.S. 3,~51,886 Hurlburt,U.S. 3,757,498, Hill,U.S. 3,813,855 and Regehr,U.S. 3,849,og5 These show the use of solid, planar-wall vanes, having various catchments or arrangements to drain the liquid removed. How-ever, such protrusion catchments, particularly those opening up toward the upstream side, are sub~ect to gas impact and momentum transfer to the collected liquid in the exposed pocket. The liquid is unprotected with respect to gas friction and momentum transfer and is picked up and entrained in the gas. On the other hand, turning the catchments or protrusions to the downstream side serves to introduce low-pressure accelerated gas-flow regions immediately downstream of $~
the liquid ca-tchment, which serves to suck or aspirate the liquid out of the protective pocket into the stream. These deficiencies of prior-art apparatus result in limited liquid loading or handling capability and a tendency to reentrain liquid at relatively low gas velocities.
In accordance with the teachings of the prior art, there are also provided gas-permeable structures defining serpentine passages or channels for the ga~. Typical of this prior art are Schaff,U.S. 2,567,030 and Brixius,U.S. 2,760,597.
~chaff and Brixius disclose particulate filter panels con-sisting of alternating corrugated layer~ oi paper, fly scre~n and similar materials. Such filters are for "dry" use, inas-much as the capillary nature of the internal walls would pre-vent gas permeation under liquid irrigation or a mist load.
The corrugated layers of the Schaaf and Brixius filters are horizontally disposed with alternate layers reversely corrugated.
If an attempt were made to use such devices for mist removal or other wet application, liquid drainage would be seriously impeded and highly inefficient. The filter panels of this prior art are specifically disposable--and are intended for one-time batch use until plugged, at which time such filters are either discarded or removed from service and re-worked.
It is an object of this invention to overcome the above deficiencies and drawbacks of the prior art and to provide apparatus for removing undesired components from gas flowing at high velocity which apparatus shall readily drain the impinging liquid and/or particulate, shall be readily permeable to the gas, shall not become clogged by liquids or particulates and shall not require frequent replacement.
,Summary of the Invention In accordance with this invention, mist and/or particulates are removed from a high-velocity mist and/or -- 8 ~ ~ ;r ~
particulate-laden gas stream by passing the gas through a series of generally vertical non-capillary, high-voidage, free-draining, fibrous-body means. This fibrous-body means may comprise a plurality of rows of separate fibrous-body baffles with the baffles staggered; i.e., the baffles in - each row displaced along its row with respect to the baffles in the rows upstream and downstream with respect to it. The staggering is such that the baffles in each row are aligned with the gaps between the baffles in the rows upstream and downstream from it. In this form of the invention, the ~as is partially deflected by the baffles of succeeding rows I lowing in a sinuous path sharply curved around the baffles.
The fibrous-body means may also be in the form of fibrous strips secured to the walls of sinuous or serpentine or zig-~ag vanes in the path of the gas. The gas in this case also flows in curved, sinuous or serpentine paths and in part through the strips.
In accordance with the broader aspects of this invention, solid particulate may be removed from a dry gas by passing the gas in dry condition through the ~ibrous-body means. So that the body means used in this way will not ultimately clog, it may be sprayed periodically with sufficient liquid to wash down the captured particulate.
In accordance with this invention in its specific aspects, solid particulate may also be removed by spraying the fibrous-body means with a liquid as the contaminated gas to the gas or is flowing through it. The sprayed liquid flows either counter/
in the same direction as the gas or has flow com-ponents counter-current or in the direction of the gas. There should be sufficient liquid to dissolve any soluble particulate and wash it down the fibrous bodies and to wash down the insoluble particulate. The liquid may also be injected into the flowing \
~as as a mist. In this case the mist and any particulate dissolved in it and the insoluble particulate are captured by the fibrous bodies and washed down.
The fibrous-body rneans operates both as centrifugal separator and as filter. The portion of the ~as deflected by ; the baffles or by -the vanes flows in an arcuate path and the mist and/or particulate matter is ejected by centrifugal force from the stream, impinging on adjacent baffles or walls whence it is drained. From the portion o~ the gas that flows through the baffles or fibrous strips, the mist and/or parti-culate matter is removed and washed down as described. The separate baffle structure according to this invention has advantages over the vane structure of the prior art. The resistance to gas flow; i.e., the pressure drop, is lower in velocities.
the baffle structure according to this invention at equal gas/
When used alone in this specification or in the claims, the word "fibrous" is intended to include within its scope filamentary; the word "fibrous" is also intended to include within its scope fibrous mats, ~ibbons and wire 20 systems such as steel wool and the like and non-capillary wire mesh. The fibrous-body baffles or strips used in this - invention are typica y made of bonded non-woven high-loft materials, examples of which are typically described by Taylor, U.S.
3,526,557 and Kinsley,U.S. 3,920,428 or open-celled reticulated polyurethane foam as described by Sinex,U.S. 3,190,057 or of e~panded metal. The fibrous-body material may also be a lofty, open, non-woven, three-dimensional light web ~ormd of many interlaced randomly disposed fibers as disclosed in Maisel,U.S.
B~CKGROUND OF THE INVF.NTION
This invention relates to the removal ~f undesired componen-ts from Eluids and has par-ticular rela-tionship to such removal where the fluids flow at high velocities be-tween abou-t 1,000 to 2,500 feet per minute. While in the interest of being concrete in dealing with the details of this invention, this applica-tion concerns itself with the removal of undesired com-ponents from gas, it is also applicable, in its broader aspec-ts, to the removal oE unaesired components from liquids, To the extent that this invention is so applicable to liquids, such application is within the scope of this invention~ The components which are removed from a gas may be soluble such as soluble salts or acids, for example acetic, nitric or hydrochloric acid, or insoluble particulate such as sulfur, carbon powder, fly ash or graphite. The components may also be mis-t, either initially present or deliberately, injected into the gas to dissolve sol-uble particulates and to wet and wash down insoluble particulate.
Essentially, this invention serves for gas scrubbing and/or mist elimination for high velocity gas flow, ~O Separation and removal of undesirable or contaminant particulates from a gas stream in accordance with the teachings of the prior art has been effected by two principal methods: gas filtering and centrifugal force separation. Gas filters are comprised of porous, foraminous or fibrous media, woven or non-woven through which the gas is wholly conduc-ted. Fil-ters sep-arate by means of inertial impaction and impingement of the par-ticles on the ~Eibers as the gas containing -the particles passes through the fil-ters~
~ ' For removal of small particle sizes, the fibers must be fine.
~hile gas filters are reasonably effective in particulate removal, the gas velocity through a filter must be main-tained at relatively low levels to avoid excessive and unecono-mic gas pressure drops. This is particularly true in the case of fine particulate filtration, where the particles are in the 1-20 micron size range and the fibers are very fine, typically in the 10 to 200 micron range. Gas pressure drop through a fib-rous filter is approximately proportional to the square of velocity of the gas in the -turbulent flow regime. Industrial fine particulate filters, such as baghouses, consequently have very large filter surfaces, operating typically at 5 to ~0 feet per minute gas face velocity, and are relatively expensive. Further, the optimum ranges of gas velocity through the filter media with respect to the efficiency of particle removal by the mechanisms of interception and impac-tion are invariably higher than those which can be practically and economically employed with respect to the gas pressure drop across the filter.
While fibrous or filamentary woven or felted gas filter media are applicable to particulate removal, including mist filtration, they do not readily lend themselves to continuous washing in the case of solid particulate removal or to too high liquid loads in the case of mist removal alone.
- Because of the uniformity and small size of the fluid passages through such filter media, and the competition of liquid and gas flow for these fluid flow passages, the flow capacity of the filter for gas is restricted because of the presence of liquid, or that for liquid because of the presence of the gas.
If a filter medium is used which possesses even a moderate degree of dynamic capillarity, under a specific combination of gas and liquid loadings, liquid is retained and gas flow t '~fi ~ ~ ~
choked off except at extremely hlgh gas-pressure drops.
Dynamic capillarity~ or the equivalent dynamic liquid hold-up in a medium, is the tendency to retain liquid in the pores o~ a medium~ which exists under flow conditions of the gas and the dynamic loading rate by such flow of the medium with liquid. The capillarity effect is enhanced by the continuous inaection of liquid by the flowing gas into the medium. In the case of static capillarity, the only force counteracting the capillary force is gravity. In the case of dynamic capillarity, the capillary force is counteracted in addition by the force exerted by the gas and augmented by the continuous loading of liquid. The effect of appreciable liquid loadings on such capillary filter media resulting from dynamic capillarity is to make the media behave as a virtually solid wall with respect to gas flow.
For dynamic liquid loads, such as are generated by filter washing~ even a small degree of capillarity yields significant gas flow passage closure with liquid. Additionally, if the gas stream contains solid insoluble particulates, capillary filter media are highly susceptible to solid plugging.
Rebours, U. S. 3,733,789, which is typical of the prior-art of this type, uses a sprayed tubular filter cloth to form a continuous stable film of washing liquor on the cloth through which the gas is "microsieved." Rebours' data on gas-flow resistance as a function of linear gas velocity illustrates the typically high-resistance/low-flow character-istics of the capillary filter media, whether woven cloth or compacted or felted fibrous material. Rebours' teaching is specific :for liquid "micromists" and as pointed out by Rebours, solid insoluble particles unfailingly clog the filter after a few hours of operation.
Fairs U. S. 3,135,592 also discloses an irrigated filter medium but in countercurrent liquid-gas flow. Fairs' gas velocities are about 15 feet per minute and fall into Rebours' range of 4 to 20 feet per minute representing essentially laminar, as distinct from turbulent flow, gas flow. Rebours and Fairs are limited to such low gas velocities because the ~as-flow passages are clogged with liquid. Sprayed screen devices such as those of Alliger, U. S. 3,7~3,~34, and Mare, U. S. 3,785,127, suffer from the same gas flow limitations result-ing from the necessity of trying to force both liquid and gas through uniform-opening restricted and/or capillary flow space in a filter medium. Lucas U. S. 3,370,LlOl, discloses a teaching similar to that of Fairs, except that the fibrous filter medium is deliberately operated in the flooded condition.
Centrifugal-force separators, such as devices with parallel-vane serpentine or sinusoidal-paths, or chevron or zig-zag passages, are used primarily for mist elimination, in clean gases not containing solid particulate. Such parallel vane separators are commonly used for removing liquid carryover in steam boilers, water-cooling towers, and in gas-liquid contacting apparatus such as distillation or fractionation towers, evaporators, gas-scrubbing apparatus and the like. Another area of application is the removal of mists from the air intakes of power turbines such as marine-power or propulsion plants. In such separators the fluids carrying the suspended matter is bent or deflected by the vanes and the suspended matter is eJected by centrifugal force. The force exerted on a particle of mass M is Mv , where v is the velocity of the particle and r the radius of the path. It is desirable that v should be high or r small.
Centrifugal-force impaction separators operate at much higher velocities than do ~ilter media, and are used for low-load liquid mist removal or for batch particulate removal.
In ~ig-zag sinusoidal-passage para:Llel-planar types of separators, the removed liquid must drain under the influence of gravity without accumulating wi~hin the passages or being otherwise subject to reentrainment in the gas. Liquid occur-ring either as a mist~ or as a delLberately-introduced spray wash that has been removed and col:Lected as drops or as a liquid film on surfaces exposed to the flowing gas, is sub-ject to being dragged along in the direction of gas flow by gas friction and momentum transfer. The resulting liquid carrythrough or reentrainment lowers the overall liquid removal efficiency. Various expedients have been suggested to overcome this deficiency. Hosch, U.~. 1,616,802, describes a serpentine-passage separator having liquid-collection baf~les protruding from the peaks of the corrugations. Other modi-fications of the sinusoidal or zig-zag-path vane separators are typically shown by Clark, U.S. 2~802,543, Sokolowski, U.S. 3,~51,886 Hurlburt,U.S. 3,757,498, Hill,U.S. 3,813,855 and Regehr,U.S. 3,849,og5 These show the use of solid, planar-wall vanes, having various catchments or arrangements to drain the liquid removed. How-ever, such protrusion catchments, particularly those opening up toward the upstream side, are sub~ect to gas impact and momentum transfer to the collected liquid in the exposed pocket. The liquid is unprotected with respect to gas friction and momentum transfer and is picked up and entrained in the gas. On the other hand, turning the catchments or protrusions to the downstream side serves to introduce low-pressure accelerated gas-flow regions immediately downstream of $~
the liquid ca-tchment, which serves to suck or aspirate the liquid out of the protective pocket into the stream. These deficiencies of prior-art apparatus result in limited liquid loading or handling capability and a tendency to reentrain liquid at relatively low gas velocities.
In accordance with the teachings of the prior art, there are also provided gas-permeable structures defining serpentine passages or channels for the ga~. Typical of this prior art are Schaff,U.S. 2,567,030 and Brixius,U.S. 2,760,597.
~chaff and Brixius disclose particulate filter panels con-sisting of alternating corrugated layer~ oi paper, fly scre~n and similar materials. Such filters are for "dry" use, inas-much as the capillary nature of the internal walls would pre-vent gas permeation under liquid irrigation or a mist load.
The corrugated layers of the Schaaf and Brixius filters are horizontally disposed with alternate layers reversely corrugated.
If an attempt were made to use such devices for mist removal or other wet application, liquid drainage would be seriously impeded and highly inefficient. The filter panels of this prior art are specifically disposable--and are intended for one-time batch use until plugged, at which time such filters are either discarded or removed from service and re-worked.
It is an object of this invention to overcome the above deficiencies and drawbacks of the prior art and to provide apparatus for removing undesired components from gas flowing at high velocity which apparatus shall readily drain the impinging liquid and/or particulate, shall be readily permeable to the gas, shall not become clogged by liquids or particulates and shall not require frequent replacement.
,Summary of the Invention In accordance with this invention, mist and/or particulates are removed from a high-velocity mist and/or -- 8 ~ ~ ;r ~
particulate-laden gas stream by passing the gas through a series of generally vertical non-capillary, high-voidage, free-draining, fibrous-body means. This fibrous-body means may comprise a plurality of rows of separate fibrous-body baffles with the baffles staggered; i.e., the baffles in - each row displaced along its row with respect to the baffles in the rows upstream and downstream with respect to it. The staggering is such that the baffles in each row are aligned with the gaps between the baffles in the rows upstream and downstream from it. In this form of the invention, the ~as is partially deflected by the baffles of succeeding rows I lowing in a sinuous path sharply curved around the baffles.
The fibrous-body means may also be in the form of fibrous strips secured to the walls of sinuous or serpentine or zig-~ag vanes in the path of the gas. The gas in this case also flows in curved, sinuous or serpentine paths and in part through the strips.
In accordance with the broader aspects of this invention, solid particulate may be removed from a dry gas by passing the gas in dry condition through the ~ibrous-body means. So that the body means used in this way will not ultimately clog, it may be sprayed periodically with sufficient liquid to wash down the captured particulate.
In accordance with this invention in its specific aspects, solid particulate may also be removed by spraying the fibrous-body means with a liquid as the contaminated gas to the gas or is flowing through it. The sprayed liquid flows either counter/
in the same direction as the gas or has flow com-ponents counter-current or in the direction of the gas. There should be sufficient liquid to dissolve any soluble particulate and wash it down the fibrous bodies and to wash down the insoluble particulate. The liquid may also be injected into the flowing \
~as as a mist. In this case the mist and any particulate dissolved in it and the insoluble particulate are captured by the fibrous bodies and washed down.
The fibrous-body rneans operates both as centrifugal separator and as filter. The portion of the ~as deflected by ; the baffles or by -the vanes flows in an arcuate path and the mist and/or particulate matter is ejected by centrifugal force from the stream, impinging on adjacent baffles or walls whence it is drained. From the portion o~ the gas that flows through the baffles or fibrous strips, the mist and/or parti-culate matter is removed and washed down as described. The separate baffle structure according to this invention has advantages over the vane structure of the prior art. The resistance to gas flow; i.e., the pressure drop, is lower in velocities.
the baffle structure according to this invention at equal gas/
When used alone in this specification or in the claims, the word "fibrous" is intended to include within its scope filamentary; the word "fibrous" is also intended to include within its scope fibrous mats, ~ibbons and wire 20 systems such as steel wool and the like and non-capillary wire mesh. The fibrous-body baffles or strips used in this - invention are typica y made of bonded non-woven high-loft materials, examples of which are typically described by Taylor, U.S.
3,526,557 and Kinsley,U.S. 3,920,428 or open-celled reticulated polyurethane foam as described by Sinex,U.S. 3,190,057 or of e~panded metal. The fibrous-body material may also be a lofty, open, non-woven, three-dimensional light web ~ormd of many interlaced randomly disposed fibers as disclosed in Maisel,U.S.
2,784,132 or Hoover,U.S. 29958,593. This material must also be 30 non-capillary. Another typical Eibrous-body material is a knitted-mesh pad wherein the individual layers of knitted material have been severely crimped or distorted so as to render the mesh openings non-uniform and non-capillary. To minimize gas-flow resistance through the fibrous-body baffle, internal void space of the baffle is preferably very high (high voidage), usually greater than 90~.
It is essential that the fibrous-body means be free-draining with respect to liquid, not have high wet-gas-flow resistance relative to the dry-gas-flow resistance, and be free from any tendency to flood, i.e., fill with retained liquid. To minimize liquid reentrainment, the fibrous-body means shall be of sufficient thickness along the direction of gas flow to allow rapid protected liquid drainage.
Preferably, this thickness should be not less than 1/4 inch, to provide for free drainage of liquid in the interior or downstream side of the baffle or strip. The draining stream on the downstream side is thus protected from excessive gas friction by the shielding effect of fibrous material on the upstream side of the strip. To optimize this protected-drain-age effect, it is desirable that the gas flow be generally horizontal with the fibrous-body baffles or strips disposed in a substantially vertical pssition completely across the stream so that no gas flows under the baffles. Liquid drainage then occurs with minimum retardation and frictional drag by the gas flow, and is sufficiently rapid so that the fibrous-body baffles and strips may be continuously spray-irri-gated without any significant accumulation of liquid.
The fibrous-body means may, in the practice of this invention, be arranged in different configurations, such as to define serpentine passages with parallel-planar walls or chevron arrangements or as separate baffles in staggered rows or as deflecting panels arranged in series in the direction of flow. Such configurations of whatever form are referred to herein as imparting to the gas a circuitous path. When a serpentine-passage con~iguration is used, the preferred angle o~ inclination, of the longer dimension of the transverse cross section of the strip, with respect to the direction of gas flow is between 20~ and 70. Typically, the pourous bodies are secured to vanes guiding the gas in circuitous paths. When a staggered ba~fle arrangement is used, the angle of inclina-tion of the length dimension of the transverse cross-section of the baffle may range from 90 (normal to gas flow dixec-tion) to 30. Along their heights the strips or baffles are generally vertical.
In some applications, it may be preferable to employ a fibrous body with anisotropic properties with respect to gas flow and gas-flow resistance. For example, a fibrous body constructed or fabricated in layers or sheets generally parallel to the outer surfaces will normally have lower gas flo~ resistance for flow parallel to such layers than for gas ~low normal to such layers. Such an anisotropic fibrous body may be used to afford a higher degree of protection from gas friction of liquid drainage in the interior of the fibrous body by orienting the anisotropic fibrous body so that the hi~h-resistance gas flow path is normal to the exterior surface of major dimension. Alternately, if protection of liquid drainage is a secondary consideration and augmented gas flow through the fibrous body is desired, the preferred - orientation of an anisotropic fibrous body would then be such that the low-resistance gas flow path is normal to the exterior surface of major dimension.
Brief Description of the Drawings For a better understanding o~ this invention, both as to its organization and as to its method of operation, togetner with adclitional objects and advantages thereof re~erence is made to the following description, taken in connection with the accompanying drawings, in which:
.. . .
1 Figure 1 .is a view in perspective with part of the top wall 13 o~ the duct or conduit 11 broken away, showing an embodiment of this invention;
Figure 2 is a plan view showing one stage of fibrous body baffles 25 of the embodiment shown in Figure l;
Figure 3 is a view in perspective of a bracket used to hold and drain the fibrous-body baffles of the embodiment shown in Figure l;
Figure 4 is a graph showi;ng the relationships between the pressure drop and gas velocity for the apparatus shown in Figure 1 and for the same apparatus with wood baffIes;
Figure 5 is a graph showing the pressure drop through a ibrous body used in the practice of this invention as a function of the velocity;
Figure 6 is a plan view of a modification of this invention including sinuous, zig-zag, or serpentine vanes having fibrous bodies mounted thereon;
Figure 7 is a plan view, generally diagrammatic of another modification of this invention;
Figure 8 is a plan view, generally diagrammatic, of a further modification of this invention;
Figure 9 is a view in transverse section enlarged through an anisotropic baEfle positioned to offer low resistance to the gas; and Figure 10 is a view in transverse section enlarged through an anisotropic baffle positioned to o~fer higher resistance to the gas.
DET~ILED DESCRIPTION OF INVENTION
The appara-tus shown in Figures 1, 2, 3 inculdes a ~ duct or conduit or flow channel 11 for treating the gas. This '. ' ` ' :
.
, ~ ' ' ' ~ `
67~7 1 duct is in the ~orm of an open-ended box having a top wall 13, - a bottom wall 15 and side walls 17 and 19. The -top 13 has openings 20 for mounting of the baffles 25, but these openings are closed by plates (not shown) after the baffles 25 are mounted. Within the duct 11 there is fibrous-body means in the form of two stages 21 and 23 of fibrous-body baffles 25, each stage having a plurality of rows 27 and 29 of the baffles 25. While the embodiment shown in Figures 1, 2, 3 has only , ': ' ' ' ~ :
, -`'`
6~
1 two rows of baffles per stage, there may be a larger number of rows per stage. The duct 11 extends horizontally and each baffle 25 is mounted substantially vertically and is of fibrous, high-voidage, non-capillary, free-draining material. The baffles 25 in different rows 27 and 29 are staggered with respect to each other, the baffles in row 29 being displaced along the row with respect to the baffles along row 27 so that the baffles 25 of row 29 are coextensive with the spaces between the baffles of row 27.
10The fibrous body 30 of each baffle 25 is mounted in a frame 31 formed of a channel section 33 and bars 35 and 37 extending from one lip of the channel and an angle section 39 secured between the extending ends of the bars 35 and 37. The fibrous body 30 is in the form of a rectangular parallel-piped and it abuts the web of the channel section 33 along the thick-- ness dimension of the body 30, the bars 35 and 37 at its upper and lower ends along the width dimension and the angle 39 along one edge (Fig. 1~. The frame 31 is secured by welding or otherwise to the bottom 15 of the duct 11. The channel 33 extends below the fibrous body 30.
The row 27 requires a different orientation of bracket 31 than the row 29. The bracket shown in Figure 3 is appropriate for the bodies 30 of the second row 29. For the third row 27 the bars 35 and 37 and the angle 39 should be on the left-hand side of the channel 33 with reference to Figure 3 (see Figure 2).
As shown in Figure 2, the baffles 25 in the first row 27 are at about ~45 to the direction of gas flow and the baffles 25 in the second row 29 are at about -45 to the direction of gas flow. Typically, this angle may vary from 90, perpendicular to the gas-flow direction, to ~ and - 30 to the gas-flow direction.
Below each stage 21 and 23 there is a tank al. The pro-jecting ends of the channels 33 extend into the tank. Typi-cally each Eibrous body 30 is 2-3/4 inches long, '7 _ lLI _ 1 inch wide and 12 inches deep. The spacing between adjacent baffles of each row and between the baffle on the first row 27 and the adjacent baffle of a succeeding row 29 is 1 inch.
The apparatus includes spray headers 43 to which nozzles 45 are connected. A liquid, t~pically water, is supplied to the headers 43 and projected ~s a spray L17 towards the downstream sides of the ~h~n~e' 11. As shown~
the spray also impinges on the ba~f:Les 25 of the stage 21. A
like nozzle may be disposed betwe~n the ~irst stage 21 and the second stage 23. In accordance with an aspect of this invention, the nozzles may be provided on the downstream sides of the t~ J ~7 stages 21 and 23. Such nozzles liqui~ the baffles 25~so that particulate from dry ~as passing through and captured by the fibrous-body means is washed down.
In the use of the apparatus, gas (air) at a high velocity is transmitted through the duct in a substantially horizontal stream in the direction of the arrow 51. The gas picks up liquid mist from the sprays 47 and so misted passes through the stages 21 and 23 of baffles 25. As shown by the arrows in Figure 2~ the gas partly passes through the fibrous bodies 30 and partly is deflected by the bodies and then is deflected and passes through other fibrous bodies 30. A
portion of the gas stream passing through a fibrous body gives up its mist and/or its particulate to the fibers; a portion also impinges on the channel section 33 and gives up its mist the captured mist drains and/or particulate to the section 33. The liquid resulting from/
through the fibrous body and through the channel section 33 into container 41, whence it may be removed. The bottom 15 is provided with holes 50 under the channels through which the liquid flows into tanks 41. The gas flowin~ through each fibrous body 30 f~rces a large part of the mist captured by the ~ibers onto the channel section 33. ~or this reason the drained through the preponderant portion of the liquid resulting ~rom the mist is/
channel section 33 into the tank 41. The channel sections 33 1~ e~tend into the pooll50 formed in the tank ~1. The liquid which drains along the channels sections 33 is protected from reentrainment by the upstream portion of the fibrous body 30 and by the base 15 of the duct 11.
The duct 11 is provided with flanges 53 so that a number of double stages may be connected in series. A
plurality of ducts 11 as shown in Figure 1 may be stacked to form a high duct. In this case the tanks 41 extend only from the base 15 of the lowermost duct. Each duct has a bottom for supporting the baffles 25, but only the upper-most duct has a top 13. The baffles 25 along the stacked ducts are coextensive. The liquid drains along the coexten-sive baffles 25 through the holes ~ in each base 15 or through enclosed horizontal troughs.
The orientation of the fibrous baffles 25 and the thickness of such baffles are both dependent on the density and gas flow resistance of the fibrous baffle material. The preferred gas linear velocity range of operation of the apparatus shown in Figures 1-3 in the practice of this invention is from 1000 to 2500 ft./min., based on the super-ficial or empty cross-sectional gas flow area. Within this range, it has been discovered that a surprisingly hi~h degree of gas flow is obtained through relatively thick fibrous baffles 25, used in the practice of this invention, at gas pressure drops that are substantially less than those that are obtained with flow through identical solid-body baffle configurations. This was determined by the following comparison tests:
.
.
.
L~ 7i~'7 These tests were carried out with apparatus in accordance with this invention, as shown in Figures 1 through
It is essential that the fibrous-body means be free-draining with respect to liquid, not have high wet-gas-flow resistance relative to the dry-gas-flow resistance, and be free from any tendency to flood, i.e., fill with retained liquid. To minimize liquid reentrainment, the fibrous-body means shall be of sufficient thickness along the direction of gas flow to allow rapid protected liquid drainage.
Preferably, this thickness should be not less than 1/4 inch, to provide for free drainage of liquid in the interior or downstream side of the baffle or strip. The draining stream on the downstream side is thus protected from excessive gas friction by the shielding effect of fibrous material on the upstream side of the strip. To optimize this protected-drain-age effect, it is desirable that the gas flow be generally horizontal with the fibrous-body baffles or strips disposed in a substantially vertical pssition completely across the stream so that no gas flows under the baffles. Liquid drainage then occurs with minimum retardation and frictional drag by the gas flow, and is sufficiently rapid so that the fibrous-body baffles and strips may be continuously spray-irri-gated without any significant accumulation of liquid.
The fibrous-body means may, in the practice of this invention, be arranged in different configurations, such as to define serpentine passages with parallel-planar walls or chevron arrangements or as separate baffles in staggered rows or as deflecting panels arranged in series in the direction of flow. Such configurations of whatever form are referred to herein as imparting to the gas a circuitous path. When a serpentine-passage con~iguration is used, the preferred angle o~ inclination, of the longer dimension of the transverse cross section of the strip, with respect to the direction of gas flow is between 20~ and 70. Typically, the pourous bodies are secured to vanes guiding the gas in circuitous paths. When a staggered ba~fle arrangement is used, the angle of inclina-tion of the length dimension of the transverse cross-section of the baffle may range from 90 (normal to gas flow dixec-tion) to 30. Along their heights the strips or baffles are generally vertical.
In some applications, it may be preferable to employ a fibrous body with anisotropic properties with respect to gas flow and gas-flow resistance. For example, a fibrous body constructed or fabricated in layers or sheets generally parallel to the outer surfaces will normally have lower gas flo~ resistance for flow parallel to such layers than for gas ~low normal to such layers. Such an anisotropic fibrous body may be used to afford a higher degree of protection from gas friction of liquid drainage in the interior of the fibrous body by orienting the anisotropic fibrous body so that the hi~h-resistance gas flow path is normal to the exterior surface of major dimension. Alternately, if protection of liquid drainage is a secondary consideration and augmented gas flow through the fibrous body is desired, the preferred - orientation of an anisotropic fibrous body would then be such that the low-resistance gas flow path is normal to the exterior surface of major dimension.
Brief Description of the Drawings For a better understanding o~ this invention, both as to its organization and as to its method of operation, togetner with adclitional objects and advantages thereof re~erence is made to the following description, taken in connection with the accompanying drawings, in which:
.. . .
1 Figure 1 .is a view in perspective with part of the top wall 13 o~ the duct or conduit 11 broken away, showing an embodiment of this invention;
Figure 2 is a plan view showing one stage of fibrous body baffles 25 of the embodiment shown in Figure l;
Figure 3 is a view in perspective of a bracket used to hold and drain the fibrous-body baffles of the embodiment shown in Figure l;
Figure 4 is a graph showi;ng the relationships between the pressure drop and gas velocity for the apparatus shown in Figure 1 and for the same apparatus with wood baffIes;
Figure 5 is a graph showing the pressure drop through a ibrous body used in the practice of this invention as a function of the velocity;
Figure 6 is a plan view of a modification of this invention including sinuous, zig-zag, or serpentine vanes having fibrous bodies mounted thereon;
Figure 7 is a plan view, generally diagrammatic of another modification of this invention;
Figure 8 is a plan view, generally diagrammatic, of a further modification of this invention;
Figure 9 is a view in transverse section enlarged through an anisotropic baEfle positioned to offer low resistance to the gas; and Figure 10 is a view in transverse section enlarged through an anisotropic baffle positioned to o~fer higher resistance to the gas.
DET~ILED DESCRIPTION OF INVENTION
The appara-tus shown in Figures 1, 2, 3 inculdes a ~ duct or conduit or flow channel 11 for treating the gas. This '. ' ` ' :
.
, ~ ' ' ' ~ `
67~7 1 duct is in the ~orm of an open-ended box having a top wall 13, - a bottom wall 15 and side walls 17 and 19. The -top 13 has openings 20 for mounting of the baffles 25, but these openings are closed by plates (not shown) after the baffles 25 are mounted. Within the duct 11 there is fibrous-body means in the form of two stages 21 and 23 of fibrous-body baffles 25, each stage having a plurality of rows 27 and 29 of the baffles 25. While the embodiment shown in Figures 1, 2, 3 has only , ': ' ' ' ~ :
, -`'`
6~
1 two rows of baffles per stage, there may be a larger number of rows per stage. The duct 11 extends horizontally and each baffle 25 is mounted substantially vertically and is of fibrous, high-voidage, non-capillary, free-draining material. The baffles 25 in different rows 27 and 29 are staggered with respect to each other, the baffles in row 29 being displaced along the row with respect to the baffles along row 27 so that the baffles 25 of row 29 are coextensive with the spaces between the baffles of row 27.
10The fibrous body 30 of each baffle 25 is mounted in a frame 31 formed of a channel section 33 and bars 35 and 37 extending from one lip of the channel and an angle section 39 secured between the extending ends of the bars 35 and 37. The fibrous body 30 is in the form of a rectangular parallel-piped and it abuts the web of the channel section 33 along the thick-- ness dimension of the body 30, the bars 35 and 37 at its upper and lower ends along the width dimension and the angle 39 along one edge (Fig. 1~. The frame 31 is secured by welding or otherwise to the bottom 15 of the duct 11. The channel 33 extends below the fibrous body 30.
The row 27 requires a different orientation of bracket 31 than the row 29. The bracket shown in Figure 3 is appropriate for the bodies 30 of the second row 29. For the third row 27 the bars 35 and 37 and the angle 39 should be on the left-hand side of the channel 33 with reference to Figure 3 (see Figure 2).
As shown in Figure 2, the baffles 25 in the first row 27 are at about ~45 to the direction of gas flow and the baffles 25 in the second row 29 are at about -45 to the direction of gas flow. Typically, this angle may vary from 90, perpendicular to the gas-flow direction, to ~ and - 30 to the gas-flow direction.
Below each stage 21 and 23 there is a tank al. The pro-jecting ends of the channels 33 extend into the tank. Typi-cally each Eibrous body 30 is 2-3/4 inches long, '7 _ lLI _ 1 inch wide and 12 inches deep. The spacing between adjacent baffles of each row and between the baffle on the first row 27 and the adjacent baffle of a succeeding row 29 is 1 inch.
The apparatus includes spray headers 43 to which nozzles 45 are connected. A liquid, t~pically water, is supplied to the headers 43 and projected ~s a spray L17 towards the downstream sides of the ~h~n~e' 11. As shown~
the spray also impinges on the ba~f:Les 25 of the stage 21. A
like nozzle may be disposed betwe~n the ~irst stage 21 and the second stage 23. In accordance with an aspect of this invention, the nozzles may be provided on the downstream sides of the t~ J ~7 stages 21 and 23. Such nozzles liqui~ the baffles 25~so that particulate from dry ~as passing through and captured by the fibrous-body means is washed down.
In the use of the apparatus, gas (air) at a high velocity is transmitted through the duct in a substantially horizontal stream in the direction of the arrow 51. The gas picks up liquid mist from the sprays 47 and so misted passes through the stages 21 and 23 of baffles 25. As shown by the arrows in Figure 2~ the gas partly passes through the fibrous bodies 30 and partly is deflected by the bodies and then is deflected and passes through other fibrous bodies 30. A
portion of the gas stream passing through a fibrous body gives up its mist and/or its particulate to the fibers; a portion also impinges on the channel section 33 and gives up its mist the captured mist drains and/or particulate to the section 33. The liquid resulting from/
through the fibrous body and through the channel section 33 into container 41, whence it may be removed. The bottom 15 is provided with holes 50 under the channels through which the liquid flows into tanks 41. The gas flowin~ through each fibrous body 30 f~rces a large part of the mist captured by the ~ibers onto the channel section 33. ~or this reason the drained through the preponderant portion of the liquid resulting ~rom the mist is/
channel section 33 into the tank 41. The channel sections 33 1~ e~tend into the pooll50 formed in the tank ~1. The liquid which drains along the channels sections 33 is protected from reentrainment by the upstream portion of the fibrous body 30 and by the base 15 of the duct 11.
The duct 11 is provided with flanges 53 so that a number of double stages may be connected in series. A
plurality of ducts 11 as shown in Figure 1 may be stacked to form a high duct. In this case the tanks 41 extend only from the base 15 of the lowermost duct. Each duct has a bottom for supporting the baffles 25, but only the upper-most duct has a top 13. The baffles 25 along the stacked ducts are coextensive. The liquid drains along the coexten-sive baffles 25 through the holes ~ in each base 15 or through enclosed horizontal troughs.
The orientation of the fibrous baffles 25 and the thickness of such baffles are both dependent on the density and gas flow resistance of the fibrous baffle material. The preferred gas linear velocity range of operation of the apparatus shown in Figures 1-3 in the practice of this invention is from 1000 to 2500 ft./min., based on the super-ficial or empty cross-sectional gas flow area. Within this range, it has been discovered that a surprisingly hi~h degree of gas flow is obtained through relatively thick fibrous baffles 25, used in the practice of this invention, at gas pressure drops that are substantially less than those that are obtained with flow through identical solid-body baffle configurations. This was determined by the following comparison tests:
.
.
.
L~ 7i~'7 These tests were carried out with apparatus in accordance with this invention, as shown in Figures 1 through
3 but with only one stage 21 of baffles. The fibrous baffles 25 were each 1" thick, 2-3/4" long, and 12" high. The baffles were non-capillary, bonded, non-woven, high-loft pads of 40-micron diameter polyester fibers bonded with a polyvinylchloride resin. The gas flow section through the baffles was 12'~
square. In a test gas flow was supplied by a 7.5 HP blower, ducted to the ~low section by a 12" diameter, 5 ft. long, rigid aluminum pipe. Pressure drop was measured by means o~ an inclined manometer across the test section. For comparison purposes, the operation of the apparatus shown in Figures 1-3 wa3 compared to the operation of similar mock-up apparatus in which the baffles are of solid wood. The results are shown in the following Table I:
TABLE I
` (a) ~ood Baffles ~elocity, fpm ~P, in in~ H20 1484 2.7 1625 3.2 `~ 1696 3.8 ` 1837 4.5 1660 3.5 1784 4.1 (b) Fibrous Baffle 1682 2.0 1893 2.5 2209 3.0 ; 2l~36 3-5 These data are plotted in Figure 4, as log of I 6~
pressure drop vs. log of linear velocity. In this t~t~, .
: - ' ' - ~:
log of pressure drop, ~P3 in inches of water, is plotted vertically and log of gas velocity in feet per minute is plotted horizontally. Curve F is for the fibrous baffles 25 and curve W for the wooden baffles.
Table I shows that the fibrous-body ba~fles trans-mitted a significant fraction of the gas as is manifest from the remarkably lower pressure drop at equal superficial gas velocities. This decrease in pressure drop is substantially greater than was anticipated. The gas flow through the fibrous-body ba~fles 25 can be determined approximately on the assump tion that pressure drop in turbulent gas flow across an obstructed flow system is proportional to khe square of the gas velocity. Figure 4 shows this to be a fair approximation as the slopes of the linear graphs is 2.
(d Pf/aPW) = (vf/vw)2 where a Pf~ ~Pw = Pressure drop across fiber and wood baffles, respectively.
Vf~VW = Ratio of gas flows external to baffle bodies, fiber or wood With reference to Figure 4, at V = 2000 ft./min.
(Vf/VW)2 = (~ P~/ aPW) = (2.6/5.0) and (Vf~Vw)2 = 0.52 and Vf = (0.52)1/2 Vw = 0.72 Vw so that at least 28~ of the gas flow must go through, rather than around, the fiber body elements. The number of stages in series necessar~ to pass a total of 95~ of the gas through the fibrous pads can be calculated as:
95 = 10() [1~ f)n]
where f = Fraction of gas going through fibrous boclies in one stage 21 or 23 of Fig. 1.
n = Nurnber of stages required for 95~ gas transmission through fibrous bodies.
.
95/100 = [1-(1 - 0.28)n]
(0.72)n = 0.05 n = 9.1 stages Implicit in the above calculation are two off-setting ass~nptions. First, it is assumed that there is negligible ,C,'I F I
~lo~ resistance ~or gas flow through the fibrous-body f~ble~-or pads and second, that no pressure-drop correction is neces-sary for the reduction in inter-baf~le passageway velocity resulting from the flow through the fibrous baffles 25. To arrive at a corrected baffle gas transmission estimate, data ~ere taken on the pressure drop of the fiber~body pad used in the above tests when employed as a direct-filter material (100 gas transmission). This data is presented in the following Table II and is plotted in Figure 5. In Figure 5 lo~ of pressure drop, ~P, in inches of water is plotted vertically and log of velocity in feet per minute horizontally.
TABLE II
Linear ~elocity, fpm ~ P, in inches of H20 1848 2.0 2046 2.5 2508 3.5 From Figures 4 and 5 the separate inter-baffle gas ` velocity and the velocity of the gas transmitted through the baffles 25 are obtainable. These values are obtained by trial-and-error calculation of the separate component pres-; sure drops based on the assumption that the separate pressure drops should add up to the experimentally-determined total pressure drop.
The 2.6 inch pressure-drop at a superficial linear velocity o~ 2000 fpm (Figure 4) consists of two components: a partial "solid-baffle" pressure drop, ~ Pi, due to the in-ter-baffle velocity, Vi, and a pad-flow pressure loss, ~Pf, due to gas flow at Vf feet/minute through the pads. The sum of the two velocities must equal the total velocity of 2000 ~eet~minute, From the pressure drop data of Figure ll and the pressure drop behavior of the pad material at 100~ gas transmission (Figure 5), it is possible to estimate pad flow by trial-and-error calculations. At the superficial velocity of 2000 ~eet/minute, it is found that the velocity through the pad is 80o feet/minute, indicating 405~ gas-flow trans-mission through the pad. For this level of flow trans-mission, 5.9 stages would be required for filtration of 95~ of the gas through the pads. This method offers a fairly straightforward technique for choosing the optimum fiber-body Qad or baffle thickness, material characteristics, orientation and number of stages.
The effectiveness of the apparatus in accordance with this invention as shown in ~igures 1-3 as a mist eliminator was demonstrated as described in the following Example I:
Example I
This operation was carried out with the two-stage apparatus as shown in Figures 1 through 3 with the non-ca~illary, bonded, high-loft pads (baffles) 25 of the com-position, bonding~ and dimensions used in the above test. Air carrying water fog was conducted through this apparatus. The air was supplied at 2000 ft./min. linear velocity in the test section. An atomized water fog 47 (Figure 1) was gen-erated by sonic nozzle 45 No. SDC 125~ made by Sonic Develop-ment Company. Air pressure of 40 pounds per square inch gauge was used in the nozzle 45, as recommended by the manufacturer, to generate the finest practicable mist. The nozzle 45 injected the mist 47 upstream of the first stage of baffles.
For comparison purposes, wooden baf~les were used in place of - the fibrous baf~les 25. In addition, the apparatus according to this invention was compared with two stages o~ a high-velocity commercial vane-type eliminator, the "Euroform"
eliminator disclosed by Regehr (Supra) and also in a leaflet entitled ~IUNTERS EUROFORM D-MIST-R. Visual methods of assessing water fog penetrakion were used. In addition, the Tyndall dispersion ef~ect on a stron~ light beam placed normal to the ~low direc-- tion at the gas outlet was observe~. Typical results are presented in Table III.
: TABLE III
Visual and Tyndall Beam Determination of Fog Penetration ~elocity = 2000 ft/. min.
UNIT TESTEDOBSERVED PENETR~TIO~
2--stage Wood Baffles Heavy 2--stage Fiber-Ba~fles None 2--stage vane-type eliminator (see above) Light The air exiting the apparatus according to this 20 invention was observed ko be at the air wet-bulb temperature and was saturated with water. This indicates that heat and mass transfer in the practice of this invention takes place at a high rate and efficiently in spite of the fact that at the high gas (air) velocity, the residence time of the liquid in the gas is extremely short.
The apparatus according to this invention thus serves as a gas absorber or for general mass-transfer as well as a compact direct wet heat exchanger. Because of the effective-ness of the apparatus for mist removal and the unique inter-action between the liquid droplets and ~ibers of the pad, theapparatus accordi.ng to this invention has advantages as a wet par-ticulate scrubber.
_ 21 -In conventional particulate-removal by wet ~r spray scrubbing or venturi scrubbers, water is atomized either at a spray nozzle or by gas frictional shear and injected into the gas stream containing the particulates which are to be removed. The gas is con~:ined in a shell or a duct or a conduit and moves at a high veloc-ity relative to the fixed spray nozzle or initial gas-liquid contact region. The atomized water spray leaving the in:itial gas-liquid contact region is at a lower velocity than the gas and is rapidly accelerated by the gas stream until the water droplets 3chieve the velocity of the gas stream a relatively short distance downstream from the nozzle or initial contact zone.
Only during the acceleration period do the spray droplets possess a differential velocity relative to the particulates in the gas stream and only during this period do the water droplets offer an impingement target for collision with the particles moving along with the gas at the gas velocity.
Collision capture is a function of the relative velocity of the particles and droplets. Obviously, once the droplets attain the same velocity as the particulates, there is virtually no chance of particulate collision-capture by the drops, so that venturi and spray scrubbers only operate in the relatively short droplet acceleration zone.
In the practice of this invention, the atomized water droplets, after -they have been partially or wholly accelerated to the velocity of the gas stream, are captured by the fiber composing the fibrous baffle o~ this invention.
Collision and momentary adherence of a droplet to a ~iber brings the droplet to a rest position, so that the relative velocity o~ the particles with respect to the captured droplet is the fu:ll velocity of the gas stream passing the fiber. On the outer or upstream fiber layers, the velocity of the gas is essentially that of the free gas stream, while for interior fibers removed ~rom the upstream face, the relative velocity is that of the portion of the gas flowing through the fibrous-body means (ba~fles 25 or vanes carrying ~ibrous bodies). At high gas velocities, the droplet tends to either be reentrained by gas friction for subsequent recapture by a deeper fiber, or grow by capture and coales-cence with other droplets. Those droplets that grow in size by capture coalescence with other drops are rapidly drained off down the fiber under the influence of gravity, or become unstable in the presence of gas frictional forces and shatter ` into smaller droplets. Because gas friction is moderated in the interior and downstream portions of the ~ibrous-body baf~les, the growth-drainage mechanism dominates in these regions. However, because larger drops tend to be quickly removed, the movins gas and the particles it contains are exposed in the practice of this invention to a dynamic drop population in which the smallest drop sizes predominate, and in which a significant portion of these droplets are held at rest or in retarded flight relative to the velocity of the particles. The efficiency of droplet capture o~ fine particles is governed by the number and size of the target droplets, as well as the relative particle-droplet velocity. For a given quantity or rate of spray liquid injection, the number of droplet targets is inversely proportional to the size of the drops, so that smaller drops provide a larger number of targets than do larger drops, and the collection efficiency is greater for a smaller mean droplet size. Further, for fine particles a general rule o~ thumb relating collection efficiency to target size is that the maximum impingement efficiency occurs when the target diameter is approximately 5 to 10 times that of the particle diameter. By controlling the initial drop-size distribution at the spray nozzle, and the fiber count and fiber diameter of the fibrous-body baffle, this efficiency can be optimized for a particulate size or r~ t~
1 size distribution. This phenomenon only occurs for non-capillary fibrous body means. In the case of capillary bodies the gas flow is bloc~ed by the liquid which fills the pores of the bodies.
EX~MPLE; II
The apparatus according to this invention as shown in Figures 1-3 was used to test for particulate~removal efficiency using a fine fly ash obtained from a local power plant of Duquesne Light Company in Allegheny County, Pennsylvania. The fly ash had been collected from the combustion gas by means of an elec-tro-static precipitator and microscopic examination showed that itcontained a significant fraction of less than l micron particle sizes In the apparatus used in this example there were two stages; the first stage 21 upstream, a primary irrigated collec-tion stage and downstream stage 23, a demisting stage. Each stage contained three rows of fibrous pads or baffles. The primary collection staye 21 included -three rows of stainless steel wire pad elements 25, made from corrugated knitted-mesh ~ire, each pad 3/4 inch thic~ and otherwise having the same dimensions as the elements of Example I The demisting stage 23 consisted of three rows of the fibrous elements used in Example I
The primary collection stage was sprayed concurrent with gas flow, using a Bete Fog Nozzle Company Type ST6FCN spray nozzle 4S, operated at 225 psig water pressure, giving a flow rate of 3 4 GPM Gas flow was 1648 CFM~ as determined by pitot-tube traverses, to arrive at the average velocity and the overall pressure drop was 5" of water A 250-gram weighed sample of the fly ash was fed :into the suction side of the air blower over a period of 45 seconds to yield a high inlet loading of more than 3 grains per standard cubic foot. The water draining from each stage during the test ` , ' - 2~ d ~
as collected, filtered, and the recovered solids dried and weighed. The weight of the recovered fly ash was 207 grams, representing a weight recovery of 82.8~. In view of the unrecoverable losses to the walls and unwashed parts of the system, and the fact that only one wetted-fibrous body stage 21 was employed, the 82.8~ direct recovery is remarkably high.
The apparatus shown in Figure 6 includes a hori-zontal flow channel or conduit 60 within which a plurality of vertical, generally parallel spaced vanes 61 of serpentine shape are mounted. Typically the vanes are composed of 1/8" thick ~-sbyrene panels and are spaced about 1" apart. Spaced along the opposite faces of each vane 61 there are a plurality of vertical pads 63 of fibrous, high voidage, non-capillary, - free-drainage material. The pads 63 may be secured to the vanes by an adhesive. The conduit has a top and a bottom (not shown) and the vanes 61 and pads 63 extend from the top to the bottom. A high velocity horizontal stream of mist--and~or--particle-laden gas passes through the conduit 60. The mist and~or particles are captured by the fibrous pads and washed down through the pads 63 and along the vanes 61 under the pads.
The apparatus shown in Figure 7 includes in a horizontal flow channel or duct 71 similar to the duct 11 of Figure 1 within which there are a plurality of vertical baffles 73. Each ba~fle 73 includes a generally cylindrical screen 75 on the outer surface of which there is an annulus 77 of fibrous, high-voidage, non-capillary free-draining material. The baffles extend between the top and bottom (not shown) of duct 71.
1 The apparatus shown in Figure 8 includes a horizontal channel or duct 81 similar to duct 11 of Figure 1 within which there are a plurality of baffles 83. Each baffle 83 includes a generally cylindrical screen 85 within which there is a mass 87 of fibrous, high voidage, non-capillary free draining material.
The baffles 83 extend between the top and bottom (not shown) of the duct.
In the apparatus of Figures 7 and 8, one stage of two rows of staggered baffles 73 and 83 are shown. There may be any desired number of stages, each s~age having a plurality of rows of staggered baffles 73 or 83, the baffles of each row being aligned with the spaces between the baffles of preceding and succeeding rows.
Figures 9 and 10 each shows a fibrous body 100 with anisotropic properties with respect to gas flow and gas flow resistance. The body 100 is fabricated in layers or sheets 101 parallel to the outer surfaces. Such a body has lower gas-flow resistance for flow parallel to the layers 101 as shown in Figure 9 than for gas flow normal to the layers as shown in Figure 10.
While preferred embodiments of this invention have been disclosad, many modifications thereof are feasible. This invention is not to be restricted except insofar as is necessitated by the spirit of the prior art.
3~
square. In a test gas flow was supplied by a 7.5 HP blower, ducted to the ~low section by a 12" diameter, 5 ft. long, rigid aluminum pipe. Pressure drop was measured by means o~ an inclined manometer across the test section. For comparison purposes, the operation of the apparatus shown in Figures 1-3 wa3 compared to the operation of similar mock-up apparatus in which the baffles are of solid wood. The results are shown in the following Table I:
TABLE I
` (a) ~ood Baffles ~elocity, fpm ~P, in in~ H20 1484 2.7 1625 3.2 `~ 1696 3.8 ` 1837 4.5 1660 3.5 1784 4.1 (b) Fibrous Baffle 1682 2.0 1893 2.5 2209 3.0 ; 2l~36 3-5 These data are plotted in Figure 4, as log of I 6~
pressure drop vs. log of linear velocity. In this t~t~, .
: - ' ' - ~:
log of pressure drop, ~P3 in inches of water, is plotted vertically and log of gas velocity in feet per minute is plotted horizontally. Curve F is for the fibrous baffles 25 and curve W for the wooden baffles.
Table I shows that the fibrous-body ba~fles trans-mitted a significant fraction of the gas as is manifest from the remarkably lower pressure drop at equal superficial gas velocities. This decrease in pressure drop is substantially greater than was anticipated. The gas flow through the fibrous-body ba~fles 25 can be determined approximately on the assump tion that pressure drop in turbulent gas flow across an obstructed flow system is proportional to khe square of the gas velocity. Figure 4 shows this to be a fair approximation as the slopes of the linear graphs is 2.
(d Pf/aPW) = (vf/vw)2 where a Pf~ ~Pw = Pressure drop across fiber and wood baffles, respectively.
Vf~VW = Ratio of gas flows external to baffle bodies, fiber or wood With reference to Figure 4, at V = 2000 ft./min.
(Vf/VW)2 = (~ P~/ aPW) = (2.6/5.0) and (Vf~Vw)2 = 0.52 and Vf = (0.52)1/2 Vw = 0.72 Vw so that at least 28~ of the gas flow must go through, rather than around, the fiber body elements. The number of stages in series necessar~ to pass a total of 95~ of the gas through the fibrous pads can be calculated as:
95 = 10() [1~ f)n]
where f = Fraction of gas going through fibrous boclies in one stage 21 or 23 of Fig. 1.
n = Nurnber of stages required for 95~ gas transmission through fibrous bodies.
.
95/100 = [1-(1 - 0.28)n]
(0.72)n = 0.05 n = 9.1 stages Implicit in the above calculation are two off-setting ass~nptions. First, it is assumed that there is negligible ,C,'I F I
~lo~ resistance ~or gas flow through the fibrous-body f~ble~-or pads and second, that no pressure-drop correction is neces-sary for the reduction in inter-baf~le passageway velocity resulting from the flow through the fibrous baffles 25. To arrive at a corrected baffle gas transmission estimate, data ~ere taken on the pressure drop of the fiber~body pad used in the above tests when employed as a direct-filter material (100 gas transmission). This data is presented in the following Table II and is plotted in Figure 5. In Figure 5 lo~ of pressure drop, ~P, in inches of water is plotted vertically and log of velocity in feet per minute horizontally.
TABLE II
Linear ~elocity, fpm ~ P, in inches of H20 1848 2.0 2046 2.5 2508 3.5 From Figures 4 and 5 the separate inter-baffle gas ` velocity and the velocity of the gas transmitted through the baffles 25 are obtainable. These values are obtained by trial-and-error calculation of the separate component pres-; sure drops based on the assumption that the separate pressure drops should add up to the experimentally-determined total pressure drop.
The 2.6 inch pressure-drop at a superficial linear velocity o~ 2000 fpm (Figure 4) consists of two components: a partial "solid-baffle" pressure drop, ~ Pi, due to the in-ter-baffle velocity, Vi, and a pad-flow pressure loss, ~Pf, due to gas flow at Vf feet/minute through the pads. The sum of the two velocities must equal the total velocity of 2000 ~eet~minute, From the pressure drop data of Figure ll and the pressure drop behavior of the pad material at 100~ gas transmission (Figure 5), it is possible to estimate pad flow by trial-and-error calculations. At the superficial velocity of 2000 ~eet/minute, it is found that the velocity through the pad is 80o feet/minute, indicating 405~ gas-flow trans-mission through the pad. For this level of flow trans-mission, 5.9 stages would be required for filtration of 95~ of the gas through the pads. This method offers a fairly straightforward technique for choosing the optimum fiber-body Qad or baffle thickness, material characteristics, orientation and number of stages.
The effectiveness of the apparatus in accordance with this invention as shown in ~igures 1-3 as a mist eliminator was demonstrated as described in the following Example I:
Example I
This operation was carried out with the two-stage apparatus as shown in Figures 1 through 3 with the non-ca~illary, bonded, high-loft pads (baffles) 25 of the com-position, bonding~ and dimensions used in the above test. Air carrying water fog was conducted through this apparatus. The air was supplied at 2000 ft./min. linear velocity in the test section. An atomized water fog 47 (Figure 1) was gen-erated by sonic nozzle 45 No. SDC 125~ made by Sonic Develop-ment Company. Air pressure of 40 pounds per square inch gauge was used in the nozzle 45, as recommended by the manufacturer, to generate the finest practicable mist. The nozzle 45 injected the mist 47 upstream of the first stage of baffles.
For comparison purposes, wooden baf~les were used in place of - the fibrous baf~les 25. In addition, the apparatus according to this invention was compared with two stages o~ a high-velocity commercial vane-type eliminator, the "Euroform"
eliminator disclosed by Regehr (Supra) and also in a leaflet entitled ~IUNTERS EUROFORM D-MIST-R. Visual methods of assessing water fog penetrakion were used. In addition, the Tyndall dispersion ef~ect on a stron~ light beam placed normal to the ~low direc-- tion at the gas outlet was observe~. Typical results are presented in Table III.
: TABLE III
Visual and Tyndall Beam Determination of Fog Penetration ~elocity = 2000 ft/. min.
UNIT TESTEDOBSERVED PENETR~TIO~
2--stage Wood Baffles Heavy 2--stage Fiber-Ba~fles None 2--stage vane-type eliminator (see above) Light The air exiting the apparatus according to this 20 invention was observed ko be at the air wet-bulb temperature and was saturated with water. This indicates that heat and mass transfer in the practice of this invention takes place at a high rate and efficiently in spite of the fact that at the high gas (air) velocity, the residence time of the liquid in the gas is extremely short.
The apparatus according to this invention thus serves as a gas absorber or for general mass-transfer as well as a compact direct wet heat exchanger. Because of the effective-ness of the apparatus for mist removal and the unique inter-action between the liquid droplets and ~ibers of the pad, theapparatus accordi.ng to this invention has advantages as a wet par-ticulate scrubber.
_ 21 -In conventional particulate-removal by wet ~r spray scrubbing or venturi scrubbers, water is atomized either at a spray nozzle or by gas frictional shear and injected into the gas stream containing the particulates which are to be removed. The gas is con~:ined in a shell or a duct or a conduit and moves at a high veloc-ity relative to the fixed spray nozzle or initial gas-liquid contact region. The atomized water spray leaving the in:itial gas-liquid contact region is at a lower velocity than the gas and is rapidly accelerated by the gas stream until the water droplets 3chieve the velocity of the gas stream a relatively short distance downstream from the nozzle or initial contact zone.
Only during the acceleration period do the spray droplets possess a differential velocity relative to the particulates in the gas stream and only during this period do the water droplets offer an impingement target for collision with the particles moving along with the gas at the gas velocity.
Collision capture is a function of the relative velocity of the particles and droplets. Obviously, once the droplets attain the same velocity as the particulates, there is virtually no chance of particulate collision-capture by the drops, so that venturi and spray scrubbers only operate in the relatively short droplet acceleration zone.
In the practice of this invention, the atomized water droplets, after -they have been partially or wholly accelerated to the velocity of the gas stream, are captured by the fiber composing the fibrous baffle o~ this invention.
Collision and momentary adherence of a droplet to a ~iber brings the droplet to a rest position, so that the relative velocity o~ the particles with respect to the captured droplet is the fu:ll velocity of the gas stream passing the fiber. On the outer or upstream fiber layers, the velocity of the gas is essentially that of the free gas stream, while for interior fibers removed ~rom the upstream face, the relative velocity is that of the portion of the gas flowing through the fibrous-body means (ba~fles 25 or vanes carrying ~ibrous bodies). At high gas velocities, the droplet tends to either be reentrained by gas friction for subsequent recapture by a deeper fiber, or grow by capture and coales-cence with other droplets. Those droplets that grow in size by capture coalescence with other drops are rapidly drained off down the fiber under the influence of gravity, or become unstable in the presence of gas frictional forces and shatter ` into smaller droplets. Because gas friction is moderated in the interior and downstream portions of the ~ibrous-body baf~les, the growth-drainage mechanism dominates in these regions. However, because larger drops tend to be quickly removed, the movins gas and the particles it contains are exposed in the practice of this invention to a dynamic drop population in which the smallest drop sizes predominate, and in which a significant portion of these droplets are held at rest or in retarded flight relative to the velocity of the particles. The efficiency of droplet capture o~ fine particles is governed by the number and size of the target droplets, as well as the relative particle-droplet velocity. For a given quantity or rate of spray liquid injection, the number of droplet targets is inversely proportional to the size of the drops, so that smaller drops provide a larger number of targets than do larger drops, and the collection efficiency is greater for a smaller mean droplet size. Further, for fine particles a general rule o~ thumb relating collection efficiency to target size is that the maximum impingement efficiency occurs when the target diameter is approximately 5 to 10 times that of the particle diameter. By controlling the initial drop-size distribution at the spray nozzle, and the fiber count and fiber diameter of the fibrous-body baffle, this efficiency can be optimized for a particulate size or r~ t~
1 size distribution. This phenomenon only occurs for non-capillary fibrous body means. In the case of capillary bodies the gas flow is bloc~ed by the liquid which fills the pores of the bodies.
EX~MPLE; II
The apparatus according to this invention as shown in Figures 1-3 was used to test for particulate~removal efficiency using a fine fly ash obtained from a local power plant of Duquesne Light Company in Allegheny County, Pennsylvania. The fly ash had been collected from the combustion gas by means of an elec-tro-static precipitator and microscopic examination showed that itcontained a significant fraction of less than l micron particle sizes In the apparatus used in this example there were two stages; the first stage 21 upstream, a primary irrigated collec-tion stage and downstream stage 23, a demisting stage. Each stage contained three rows of fibrous pads or baffles. The primary collection staye 21 included -three rows of stainless steel wire pad elements 25, made from corrugated knitted-mesh ~ire, each pad 3/4 inch thic~ and otherwise having the same dimensions as the elements of Example I The demisting stage 23 consisted of three rows of the fibrous elements used in Example I
The primary collection stage was sprayed concurrent with gas flow, using a Bete Fog Nozzle Company Type ST6FCN spray nozzle 4S, operated at 225 psig water pressure, giving a flow rate of 3 4 GPM Gas flow was 1648 CFM~ as determined by pitot-tube traverses, to arrive at the average velocity and the overall pressure drop was 5" of water A 250-gram weighed sample of the fly ash was fed :into the suction side of the air blower over a period of 45 seconds to yield a high inlet loading of more than 3 grains per standard cubic foot. The water draining from each stage during the test ` , ' - 2~ d ~
as collected, filtered, and the recovered solids dried and weighed. The weight of the recovered fly ash was 207 grams, representing a weight recovery of 82.8~. In view of the unrecoverable losses to the walls and unwashed parts of the system, and the fact that only one wetted-fibrous body stage 21 was employed, the 82.8~ direct recovery is remarkably high.
The apparatus shown in Figure 6 includes a hori-zontal flow channel or conduit 60 within which a plurality of vertical, generally parallel spaced vanes 61 of serpentine shape are mounted. Typically the vanes are composed of 1/8" thick ~-sbyrene panels and are spaced about 1" apart. Spaced along the opposite faces of each vane 61 there are a plurality of vertical pads 63 of fibrous, high voidage, non-capillary, - free-drainage material. The pads 63 may be secured to the vanes by an adhesive. The conduit has a top and a bottom (not shown) and the vanes 61 and pads 63 extend from the top to the bottom. A high velocity horizontal stream of mist--and~or--particle-laden gas passes through the conduit 60. The mist and~or particles are captured by the fibrous pads and washed down through the pads 63 and along the vanes 61 under the pads.
The apparatus shown in Figure 7 includes in a horizontal flow channel or duct 71 similar to the duct 11 of Figure 1 within which there are a plurality of vertical baffles 73. Each ba~fle 73 includes a generally cylindrical screen 75 on the outer surface of which there is an annulus 77 of fibrous, high-voidage, non-capillary free-draining material. The baffles extend between the top and bottom (not shown) of duct 71.
1 The apparatus shown in Figure 8 includes a horizontal channel or duct 81 similar to duct 11 of Figure 1 within which there are a plurality of baffles 83. Each baffle 83 includes a generally cylindrical screen 85 within which there is a mass 87 of fibrous, high voidage, non-capillary free draining material.
The baffles 83 extend between the top and bottom (not shown) of the duct.
In the apparatus of Figures 7 and 8, one stage of two rows of staggered baffles 73 and 83 are shown. There may be any desired number of stages, each s~age having a plurality of rows of staggered baffles 73 or 83, the baffles of each row being aligned with the spaces between the baffles of preceding and succeeding rows.
Figures 9 and 10 each shows a fibrous body 100 with anisotropic properties with respect to gas flow and gas flow resistance. The body 100 is fabricated in layers or sheets 101 parallel to the outer surfaces. Such a body has lower gas-flow resistance for flow parallel to the layers 101 as shown in Figure 9 than for gas flow normal to the layers as shown in Figure 10.
While preferred embodiments of this invention have been disclosad, many modifications thereof are feasible. This invention is not to be restricted except insofar as is necessitated by the spirit of the prior art.
3~
Claims (15)
1. Apparatus for removing undesired components from a fluid, said components being at least in part liquid or said fluid containing a liquid in addition to said components, said apparatus including a generally horizontal flow channel having an inlet opening for admitting said fluid and an outlet opening for exhausting said fluid, said fluid flowing in a generally horizontal direction through said channel from said inlet opening to said outlet opening, a plurality of bodies, means mounting said bodies generally vertically and spacially separated in said flow channel in the path of said fluid so that a portion of the fluid approaching each of said bodies flows through the said approached body and a portion of said approaching fluid is deflected by said approached body and flows around said body, the said apparatus being characterized by that each of said body is formed of fibrous, high voidage, non-capillary, free-draining material, said undesired components being removed from the portion of the fluid which passes through each of said bodies by capture by the fibers of said passed-through body and drainage through said passed-through body and from the portion of the fluid which passes around each of said bodies, by centrifugal action.
2. The apparatus of claim 1 for removing undesired components from a gas stream flowing at a high velocity, charac-terized by that the bodies are of substantial thickness trans-versely to the stream, whereby the drainage through a body on the side of a body remote from the side wherein the stream is incident is protected by the body from reentrainment.
3. The apparatus of claim 2 wherein the gas is a mist-laden gas and the bodies remove and drain the mist from the gas, characterized by that the bodies are of substantial thickness transversely to the stream whereby the drainage through a body on the side of the body wherein the gas is incident is protected by the body from reentrainment.
4. The apparatus of claim 1 characterized by that the bodies are mounted in rows in the flow channel from the upstream end to the downstream end of the channel, the bodies in each row being staggered with respect to the bodies in the adjacent rows, upstream or downstream.
5. The apparatus of claim 1 for removing solid particulate from a gas stream characterized by means for injecting mist into the stream, whereby the solid particulate is captured by the bodies with the mist and is washed down by the captured mist.
6. The apparatus of claim 5 characterized by that the mist-injecting means includes a nozzle for injecting the mist, the said nozzle being mounted with its mist emitting outlet upstream of the bodies.
7. The apparatus of claim 1 wherein the channel has a top and a bottom characterized by that the mounting means for the bodies mounts the bodies so that they extend completely between the top and the bottom, whereby reentrainment of the components by fluid flowing between the bodies and the top or bottom is suppressed.
8. The apparatus according to claim 1 wherein the flow-channel has a plurality of generally vertical vanes having a form such as to guide the gas in a tortuous path, characterized
8. The apparatus according to claim 1 wherein the flow-channel has a plurality of generally vertical vanes having a form such as to guide the gas in a tortuous path, characterized
Claim 8 continued....
by that the bodies are spaced along at least one surface of each vane.
by that the bodies are spaced along at least one surface of each vane.
9. The apparatus of claim 8 wherein the bodies are spaced along the opposite surfaces of each vane.
10. The apparatus of claim 1 wherein the flow channel has a top and a bottom and wherein the mounting means include a bracket for supporting each body so that each body extends between the top and the bottom, characterized by that each said bracket has undesired component-draining member on its downstream side with respect to the flow of the fluid through or around said body, said draining member extending through the bottom of the channel.
11. The apparatus of claim 1 wherein the bodies are anisotropic with respect to gas flow and gas-flow resistance and each body has an exterior surface of major dimension and also has a high-resistance gas-flow path and the bodies are oriented by the mounting means so that the high-resistance gas-flow path of each body is normal to the exterior surface of major dimension of said body.
12. The apparatus of claim 1 wherein the bodies are anisotropic with respect to gas flow and gas-flow resistance and each body has an exterior surface of major dimension and also a low-resistance gas-flow path and the bodies are oriented by the mounting means so that the low-resistance gas-flow path of each body is normal to the exterior surface of major dimension of said body.
13. The apparatus of claim 1 wherein the bodies are anisotropic with respect to gas flow and gas-flow resistance.
14. The method of removing fine-size solid particulate from a gas with apparatus including a generally horizontal flow channel having interposed therein a plurality of generally vertical, fibrous, high-voidage,non-capillary, free-draining baffles, the said method comprising introducing into said gas a mist, conducting the mist-laden gas having the solid particulate therein through said flow channel at a high velocity thereby passing a portion of said mist-laden gas having the solid par-ticulate therein through said baffles, capturing the mist in drop form on the fibers of said baffles, producing a dynamic drop-size population on said fibers including larger and smaller drop sizes in which the smaller drop sizes predominate and capturing the fine-size particulate in said smaller drop sizes, said dynamic population being produced by growth of smaller drop sizes into larger drop sizes by capture of mist and by coalescence of drops and by rapid drainage of said larger drop sizes, the drops drained containing the solid captured particulate.
15. The method of removing solid particulate from a gas with apparatus including a generally horizontal flow channel having mounted therein a plurality of generally vertical, fibrous, high-voidage, non-capillary, free-draining baffles, the said method comprising introducing into said gas a mist to produce a mist-laden gas with said solid particulate therein, conducting said mist-laden gas at a high velocity through said flow channel thereby passing a portion of said mist-laden gas having said solid particulate therein through said baffles, capturing the mist in drop form on the fibers of said baffles, causing certain of said captured drops to grow in size by capture-coalescence with other drops, rapidly draining off down the fiber of said baffles certain of the drops that have grown in size by
15. The method of removing solid particulate from a gas with apparatus including a generally horizontal flow channel having mounted therein a plurality of generally vertical, fibrous, high-voidage, non-capillary, free-draining baffles, the said method comprising introducing into said gas a mist to produce a mist-laden gas with said solid particulate therein, conducting said mist-laden gas at a high velocity through said flow channel thereby passing a portion of said mist-laden gas having said solid particulate therein through said baffles, capturing the mist in drop form on the fibers of said baffles, causing certain of said captured drops to grow in size by capture-coalescence with other drops, rapidly draining off down the fiber of said baffles certain of the drops that have grown in size by
Claim 15 continued,...
coalescence and thereby producing on said fibers a dynamic drop population in which the smaller drop sizes predominate, capturing particulate in said smaller drops and coalescing said smaller drops with the particulate with other drops into coalesced larger drops and draining the said larger drops.
coalescence and thereby producing on said fibers a dynamic drop population in which the smaller drop sizes predominate, capturing particulate in said smaller drops and coalescing said smaller drops with the particulate with other drops into coalesced larger drops and draining the said larger drops.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US79619877A | 1977-05-12 | 1977-05-12 | |
| US796,198 | 1977-05-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1106777A true CA1106777A (en) | 1981-08-11 |
Family
ID=25167587
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA301,418A Expired CA1106777A (en) | 1977-05-12 | 1978-04-18 | Removal of undesired components from gases |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS53139278A (en) |
| CA (1) | CA1106777A (en) |
| DE (1) | DE2820850A1 (en) |
| FR (1) | FR2390193A1 (en) |
| GB (1) | GB1594524A (en) |
| IT (1) | IT1095265B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6478859B1 (en) | 2000-11-03 | 2002-11-12 | Keith A. Ferlin | Airborne particulate removal apparatus |
| US10239016B2 (en) | 2016-12-07 | 2019-03-26 | Nuorganics LLC | Systems and methods for nitrogen recovery from a gas stream |
| US10513466B2 (en) | 2017-01-16 | 2019-12-24 | Nuorganics LLC | System and method for recovering nitrogenous compounds from a gas stream |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2122105A (en) * | 1982-06-16 | 1984-01-11 | Coopers Filters Ltd | Water-gas separator |
| USRE33444E (en) * | 1984-01-09 | 1990-11-20 | Fluid treating for removal of components or for transfer of heat, momentum-apparatus and method | |
| US4732585A (en) * | 1984-01-09 | 1988-03-22 | Lerner Bernard J | Fluid treating for removal of components or for transfer of heat, momentum-apparatus and method |
| FR2769517B1 (en) * | 1997-10-13 | 1999-11-12 | Francis Al Dullien | CROSSLINKED FOAM SPONGIOUS TYPE SEPARATOR |
| FR2777801B1 (en) * | 1998-04-28 | 2000-06-02 | Francis Al Dullien | MECHANICAL SEPARATOR FOR GASEOUS EFFLUENTS AND MANUFACTURING METHOD THEREOF |
| DE102004022312B4 (en) * | 2004-05-04 | 2009-04-16 | Daimler Ag | Moisture exchange module with a bundle of moisture permeable hollow fiber membranes |
| FR2901151B1 (en) * | 2006-05-19 | 2010-03-12 | Inst Francais Du Petrole | PARTICULATE SEPARATOR CONTAINED IN A GASEOUS CURRENT, IN PARTICULAR SOLID AND / OR LIQUID AND / OR PASSIZED PARTICLES. |
| CN101816888A (en) * | 2010-05-14 | 2010-09-01 | 孙厚杰 | Wet flue gas desulfurization absorption tower for power plant |
| CN116392898B (en) * | 2023-03-30 | 2023-10-13 | 深圳市汰洋环保科技有限公司 | Physical interception exhaust gas treatment device and control method |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1088318A (en) * | 1911-03-25 | 1914-02-24 | Charles H Bicalky | Air purifying and cooling apparatus. |
| US3616623A (en) * | 1970-01-19 | 1971-11-02 | Laurance S Reid | Mist eliminator |
| US3964886A (en) * | 1974-10-29 | 1976-06-22 | Baltimore Aircoil Company, Inc. | Gas scrubbing apparatus |
-
1978
- 1978-04-18 CA CA301,418A patent/CA1106777A/en not_active Expired
- 1978-04-27 GB GB16793/78A patent/GB1594524A/en not_active Expired
- 1978-05-12 JP JP5571778A patent/JPS53139278A/en active Pending
- 1978-05-12 DE DE19782820850 patent/DE2820850A1/en active Granted
- 1978-05-12 IT IT23337/78A patent/IT1095265B/en active
- 1978-05-12 FR FR7814316A patent/FR2390193A1/en active Granted
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6478859B1 (en) | 2000-11-03 | 2002-11-12 | Keith A. Ferlin | Airborne particulate removal apparatus |
| US10239016B2 (en) | 2016-12-07 | 2019-03-26 | Nuorganics LLC | Systems and methods for nitrogen recovery from a gas stream |
| US10513466B2 (en) | 2017-01-16 | 2019-12-24 | Nuorganics LLC | System and method for recovering nitrogenous compounds from a gas stream |
| US10934223B2 (en) | 2017-01-16 | 2021-03-02 | Nuorganics LLC | System and method for recovering nitrogenous compounds from a gas stream |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2390193A1 (en) | 1978-12-08 |
| DE2820850A1 (en) | 1978-11-23 |
| IT1095265B (en) | 1985-08-10 |
| DE2820850C2 (en) | 1988-11-24 |
| GB1594524A (en) | 1981-07-30 |
| JPS53139278A (en) | 1978-12-05 |
| FR2390193B1 (en) | 1985-05-10 |
| IT7823337A0 (en) | 1978-05-12 |
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