CA1116509A - Venturi scrubber - Google Patents
Venturi scrubberInfo
- Publication number
- CA1116509A CA1116509A CA000307444A CA307444A CA1116509A CA 1116509 A CA1116509 A CA 1116509A CA 000307444 A CA000307444 A CA 000307444A CA 307444 A CA307444 A CA 307444A CA 1116509 A CA1116509 A CA 1116509A
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- Canada
- Prior art keywords
- venturi
- orifices
- throat
- jets
- section
- Prior art date
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D47/00—Separating dispersed particles from gases, air or vapours by liquid as separating agent
- B01D47/10—Venturi scrubbers
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Separation Of Particles Using Liquids (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A venturi scrubber for removing fine particulate matter from a gas flowing through a conduit, comprising a venturi section inserted into the conduit, and having a plenum surrounding the throat portion of the venturi.
Means are provided for introducing water flow at high pressure into the plenum, and through a plurality of spaced orifices around the venturi at the throat.
hollow structural means is positioned inside the venturi, longitudinally spaced opposite the plenum, and connected to the plenum. The hollow structure divides the cross-sectional area of the throat into at least one double-walled space, through which the gas flows. A plurality of spaced second orifices are in the hollow structure, so that the pressurized water will flow outwardly from these orifices and through the wall of gas flowing through the double-walled space. The internal structure can be a circular pipe inside of a circular venturi with circumferentially-spaced orifices. It can also be a rectangular venturi with a narrow rectangular conduit connected between and through opposite walls of the throat portion of the venturi. There are second orifices on the two walls of the dividing conduit opposite first orifices on the two faces of the throat portion of the venturi.
A venturi scrubber for removing fine particulate matter from a gas flowing through a conduit, comprising a venturi section inserted into the conduit, and having a plenum surrounding the throat portion of the venturi.
Means are provided for introducing water flow at high pressure into the plenum, and through a plurality of spaced orifices around the venturi at the throat.
hollow structural means is positioned inside the venturi, longitudinally spaced opposite the plenum, and connected to the plenum. The hollow structure divides the cross-sectional area of the throat into at least one double-walled space, through which the gas flows. A plurality of spaced second orifices are in the hollow structure, so that the pressurized water will flow outwardly from these orifices and through the wall of gas flowing through the double-walled space. The internal structure can be a circular pipe inside of a circular venturi with circumferentially-spaced orifices. It can also be a rectangular venturi with a narrow rectangular conduit connected between and through opposite walls of the throat portion of the venturi. There are second orifices on the two walls of the dividing conduit opposite first orifices on the two faces of the throat portion of the venturi.
Description
This invention lies in the field of scrubbers for removing fine particula-te matter from gas flowing in a conduit. More particularly, this invention concerns a venturi-type scrubber which is inserted in-to the condui-t through which the gas flows.
Still more particularly, the design involves inserting in the interior of the throat portion of the venturi a hollow structure, or structural means, so that high velocity jets of water can be injected into and across the gas flow in the throat portion of the venturi, inwardly from the outer wall of the venturi throat, and outwardly from the wall of the hollow structure inside of the throat.
An undesirable charac-teristic of industrially produced gases which are enroute to ultimate venting to atmosphere is that, at times, they are laden with particulate matter and cannot be discharged to the atmosphere because of environmental rulings. At times the particulate size is great enough to permit reliable removal by conventional means which are available to the industry.
It is also necessary to remove particulate matter in the sub-micron and micron size range, which, because of their tiny dimensions (one micron equals 0.0000~ inch) begin to assume atomic/molecular characteristics, and are extremely difficult to remove, to a satisfactory degree from gas by filtration.
In such cases there has been resort to the venturi scrubbers for more complete particulate matter removal from the gases. As the name suggests, the venturi scrubber i9 fundamen-tally based on flow line restriction through area reduction, to a throat section, which is immediately followed by gentle area increase, in an expanding conical section following the throat, to the original line size.
Venturi flow state is used for metering of fluids, because of the flow acceleration in the reduced area throat, versus flow in the line prior to the area reduction.
However, an advantage of the venturi is that the velocity pressure of the flow at the throat is virtually completely converted back to static pressure in the gently expanding section after the throat. In the prior art, the converging section of the venturi has an angle of convergence ge.nerally of the order of 25, and in the expansion section after the throat, the included angle is generally of the order of 7.
Since the gas, and particulate matter carried by it, carry neyative charges, and the liquid injected at the venturi throat is also negatively charged, and since like charges repel, there must be means to overcome the repulsive forces between the particulate matter and the water, to permit wetting of the particulate matter, and the absorption and entrainment of the particulate matter by the liquid, for removal from the gas stream.
If the gas stream and its particulates are moving at great enough velocity at the instance of impact against water, the momentum of the solid particulates is great enough to cause them to be driven into the liquid, and, despite the repulsive effect of like charges, cause wetting absorption of the particulate matter, and removal from the gas stream.
Since it is not desirable to maintain line flow velocity great enough to permit particulate entrapment by liquids, a venturi tube is generally inserted into the gas flow line to achieve great enough gas flow velocity at the restriction throat of the venturi.
However, this higher velocity head must be converted to static pressure head, and this is accomplished by the expanding section of the venturi.
The venturi scrubber is a commonly used apparatus for the removal of particulate matter. However, as it is used in industry, and where the throat restriction becomes rectangular, after the round duct, for maximal gas-liquid contact at the throat restriction, efficiency of particulate removal is typically of the order of 95%. In some cases the 95% efficîency is not acceptable.
The improved venturi scrubber of this invention increases the efficiency of particulate removal from a gas stream to a significantly higher percentage than 95%, by providing two stages and staggered liquid injection means, for significant increase in gas-against-liquid strike, to avoid, as far as possible, the 5% particulate escape from liquid entrapment 2Q or collision, which is the best that the prior art can do.
The invention is an improved venturi scrubber for removing fine particulate matter from a flow of gas in a conduit, comprising:
(a) a venturi inserted into said conduit, comprising a converging section of selected converging angle, a throat, of selected diameter, and a diverging section of selected diverging angle;
~b) a plenum surrounding said venturi in the region upstream and down-stream of said throat, and means to conduct water flow under pressure to said plenum;
(c) a plurality of spaced first orifices, connecting from said plenum, through the wall of said venturi at said throat, whereby high velocity first jets of water will flow inwardly through said orifices into the flowing _ ~ _ 6~
gas in said venturi;
(d) internal hollow s-tructural means inside said venturi, longitudinally-spaced approximately opposite said plenum, said hollow structural means connected to said plenum; said hollow structural means dividing the area of said throat into at least one double-walled space for said gas flow;
(e) a plurality of spaced second orifices in the wall of said hollow structural means, whereby a plurality of high velocity second jets of water will flow from said second orifices outwardly into said at least one double-walled space, for said gas flow;
whereby said first and second orifices will provide, respectively, first and second high velocity jets of water into said at least one double-wailed space, to contact at high velocity said gas in said space, and to remove said particulate matter.
Also new and novel in the art of venturi scrubbing is the combination of injection directions, of the liquid jets, from both the peripheral wall inwardly of the throat, and from the internal portion of the throat outwardly toward the walls of the throat section of the venturi. This is provided for in this invention by both a round or rectangular throat restriction.
It is a primary object of this invention to provide a venturi-type scrubber, which may be either circular or rectangular in cross-section. In one respect it is similar to the prior art scrubbers in that it provides a plenum surrounding the throat portion of the venturi, into which high-pressure water is provided, and from the plenum a plurality of orifices leads through the wall of the throat of the venturi into the interior portion of the throat, providing a first series of high velocity jets of water injected radially inwardly and across into the flowing stream of gas.
In one embodiment of this invention a cylindrical pipe is placed along the axis of the venturi, over a selected region upstream and downstream from the throat. This pipe is connected to the plenum by a radial pipe connection. A plurality of orifices is circumferentially provided in the wall of this axial pipe, in a transverse plane, so that a plurality of high-pressure jets of water flow outwardly radially into the gas stream, which flows through the annular wall of gas, between the central pipe and the internal wall of the venturi. These high velocity jets cause impact mixing between the gas flow and the water so that all of the particulate matter in the high ~elocity - 5a -5~
gas stream is contacted at high velocity by the water stream, and so are wetted and collected by the water and withdrawn from the gas stream. The first jets flowing inwardly from the wall of the venturi are circumferentially spaced by a selected angle A. The second jets flowing outwardly from the central pipe, are circumferentially spaced by -the same angle A, but they are staggered by one half of that angle so that together they cover more completely the full cross-section of the gas flow. Furthermore~ the plane in which the second jets are provided is downstream a selected dimension D from the plane of the first jets, which passes through the throat of the venturi.
A second embodiment involves a square cross-section venturi, and a corresponding plenum, with the first jets at the throat in two opposite walls of the throat. The internal hollow structural means comprises a rectangular cross-section conduit. The wide faces of the conduit are between, and parallel to the two walls of the venturi that contain the first orifices. There are second orifices in the walls of the wide faces. This internal structure is connected to the plenum.
Here again, the flow of gas in the venturi is divided by the internal hollow structural means in one case into a double-walled flow of gas which is an annular wall of gas, and in the rectangular case, is formed into two flows of gas, which are rectangular in cross-section, with water injection on two opposite walls of the gas flow.
Because of the limited flow invasion into a thick ~ . .
stream of yas of a jet of water, -this direct flow, and reverse flow of jets impinging upon opposite faces of the single, or double, flows of gas unimpeded flow of each water jet due to jet plane displacement provides an opportunity for the jets of water to pass completely throuyh the wall of gas, and to impinge onto the opposite walls of the internal structure and the venturi, to splash, and provide further contact between droplets of water and the gas flow. In the case of -the rectangular venturi the plane of the second jets is spaced downstream of the plane of the first jets, by a selected distance D, and are further equally spaced from each other by the same spacing F of the first jets, but the two sets of jets are staggered by a distance F/2 so as to better contact the full cross-section of the gas flow.
A further improvement involves the use of a short cylindrical section at the throat of the venturi, of the same diameter as the throat, in case of the circular venturi, or of the same rectangular dimensions of the throat, of the rectangular cross-section venturi. The dimension of ~he constant cross-section portion, or section, of the venturi is dimensionally greater than D the spacing between the two transverse planes of the first and second jets.
These and other objects and advantages of this invention and a better understanding of the principles and details of the invention will be evident from the following description taken in conjunction with the appended drawings, in which:
Figure 1 illus-trates in vertical cross-section the circular-type venturi construction of this invention.
Figures 2 and 3 show cross-sectional views of Figure 1, respectively, taken at the planes 2-2 and 3-3 of Figure 1.
Figure 4 illustrates a variation of Figure 1, including a short section of constant diameter o~ the throat.
Figures 5 and 6 show in cross-section, in vertical and transverse cross-section, another embodiment of the invention, comprising a venturi of rectangular cross-section.
Referring now to the drawings and, in particular, to Eigure 1, there is shown one embodiment of the invention which involves a venturi of circular cross-section 10, which is inserted into a circular conduit 12 carrying gas flowing in accordance with arrows 44. Joined to the conduit 12 at the transverse plane 13 is the converging section 16 of the venturi, which reduces the cross-section for flow of gas, from that of the conduit 12, to that of the throat of the venturi at the transverse plane 28, where the converging section 16 is joined to the diverging section 18. The diverging section expands the cross-section of the throat -through a gently expanding cone of angle 65, to the original diameter of and is joined to the conduit 12 (not shown) as is well known in the art. I'he angle of convergence of the converging section is ~$~
of -the order of 25, and the angle of divergence of the diverging section is of the order of 7.
Surrounding -the throat portion from a point upstream of, to a point downstream of, the throat 28 is a plenum 20 surrounding the outer conieal surfaces 16 and 18 of the venturi. A pipe 30 serves to provide water at high pressure flowing in accordance with arrow 49 into the plenum space 26.
There is a plurality N of circumferentially~spaced first orifices 38 in the plane of the throat 28 through which water can flow in accordance with arrows 52, to provide first jets of water 48 flowing radially inwardly, as shown in FIGURE 2.
So far the description of the venturi corresponds to that which is known in the prior art.
In this invention, in addition to the inwardly flowing jets of water 48 at the throat of the venturi, there is inserted into the throat cross-section, a hollow structural means 34 which, in FIGURE 1, is shown as an ~0 axial pipe 34 closed at the upstream end 36, and connected by a radial portic>n 32 to the plenum space 26. Thus, the high pressure water flows by arrows 50 into the pipe 32 and to the axial pipe 34. There is an equal plurality N of circumferentially-spaced second orifices 42 in the pipe 34.
These are in a plane which is spaced a selected distance D, 40 downstream of the plane of the ori.fices 38. As shown in FIGURE 3, these second jets that flow through the orifices 42, flow outwardly, indicated by the numeral 56. These are called second jets as opposed to the first jets flowing through the orifices 38 inwardly from the plenum space 26.
The pressure of the water and corresponding velocity of the jets, is such that the high velocity jets will pass through the annular space for gas flow, between the internal structure 34 and the throat wall of the venturi. The velocity is sufficient to carry the jets through the gas and impinge on the opposite wall, causing a splatter, and formation of droplets which further flow turbulently into the gas flow to better contact the particulate matter.
The use of an internal structural means, such as pipe 34 and the conduit 68 of FIGUR~S 5 and 6, serves to break up the full cross-section of the throat for a flow of gas into a shape of cross-section for flow, which comprises an annular wall of gas having an outer and inner surface, which is of smaller transverse dimension than the diameter of the total cross-section of the throat. Similarly, it may be in the form of two rectangular spac-es of gas flow, eaeh of the spaees having walls which are closer spaced to the throat wall than the diameter of maximum spacing of the throat. Thus, the high velocity jets have a better chance to penetrate through the section of ~as flow, at high velocity and, thus, to impinge at high velocity on the particulate matter, sweeping it out of the gas flow. The impingement of -the jets on the opposite metal walls serves further to provide high velocity flow of droplets, to provide a turbulent mixing of high velocity water, of large surface area, and high veloci-ty, with the gas, and, thus, to provide better scrubbing of -the fine particula-te matter from the gas flow.
As shown in Figures 2 and 3, the circumferential spacing or angle A between the first orifices of Figure 2 in the wall of the venturi and the second orifices in the central pipe is preferably the same angle A, and the azimuthal position of the orifices is staggered so that the first jets and second jets will be angularly spaced by an angle A/2, between the adjacent jets. Also, the two-stage injection, where the second jets are injected at a distance D, downstream of the plane of the first jets; and staggered radial positions, makes for a greater opportunity for the water to contact all of the gas flow.
Referring now to Figure 4, there is shown a variation in a portion of the structure of the throat of the ven-turi, in which the throat includes a cylindrical element 60, of selected length 62, the diameter being equal to the throat portion of the venturi of Figure 1. This cylindrical portion 60 joins the converging portion 16 at the plane 28 and is joined to the expanding section 18 at a downstream plane 64. The spacing between the two planes 28 and 64 being a selected dimension 62.
The displacement D between the planes of the first jets 48 and second jets 56 is less than the dimension 62 of the constant diameter portion.
Whlle the con.stant diameter portion, or constant cross-sectional area portion, of the throat shown in Fiyure 4 is illustra~ed as a variation of Figure 1, which is designed for the circular cross-sec-tional venturi, it can be applied equally well -to the rectangular cross-section venturi shown in Figures 5 and 6.
Referring now to Figures 5 and 6, there is shown the throat portion of a venturi scrubber having a conversion section 72 with converging gas flow 70, to the plane of the throa~ 90, where the converging section 72 joins the diverging or expan-ding section 74. As indicated in Figure 4, the throat section could include a short section of constant cross-section, corre-sponding to that of the plane of the throat 90. A plenum 76 is provided as before, whlch is also rectangular in cross-section corresponding to that of the throat 90.
Figure 6 is a view of the throat section taken across the plane 6-6 of Figure 5. Figure 5 is a cross-sectional taken across the plane 5-5 of Figure 6. A high pressure flow of water 80 enters through an inlet pipe 78 into the space 94 of a plenum 76. This flow divides into two parts, one part 86 directed for flow through orifices 98 and providlng jets 88, flowing inwardly. Another part, illustrated by arrows 82, flows into the central hollow space 95 of structure 68 and out through orifices 84, providing jets 85 which flow outwardly into the gas spaces between the inner wall of the venturi and the outer wall of the central hollow structure 68.
As illustrated in Figure 6 the cross-section of the venturi at the throa-t is now divided by the central structure 68 into two rectangular areas 73 and 75 between opposite walls of the venturi throat 90. I'he dimension across these flows through which the jets are directed is less than one half of th~ total dimension of the throat and, therefore, these high velocity jets have a better chance of completely pene-trating the gas wall, from one surface to another, and even to impact on the opposite wall, to splatter and form high velocity droplets. These droplets rebound into the gas flow, and fur-ther tend to wash from the gas the particulate matter. As shown in Figure 6 the second jets 85 are spaced apart a dis-tance F, and are directed in opposition to the first jets 88 which are spaced apart by distance F, and are staggered by the dimension D, which is one half of the spacing F, between jets in each set~ Furthermore, as previously stated, the planes of the second jets 85 are spaced downstream by a selected distance D, from the plane of the first jets, which isin the plane 90 of the throat. Consequently, the staggering of the jets to better cover the full cross-section of the gas flow, and the two-stage injectionr and the narrowing of the dimension of the gas flow through which the water jets must pass, by use of an internal structure, provide a much-improved opportunity for high velo-city mixing of the water jets transversely, into the gas flow, and to better contact the particulate matter, and to cause it to be wetted by the wa-ter, and -to flow ou-t of the gas stream with the water, and be removed therefrom.
While the invention has been described with a certain degree of particularity, i-t is manifest that many changes may be made in the details of construction ahd the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for the purposes of exempli:Eicati.on, but is to be limited only by the scope of the attached clai~s, including the full range of equivalency to which each element thereof is entitled.
Still more particularly, the design involves inserting in the interior of the throat portion of the venturi a hollow structure, or structural means, so that high velocity jets of water can be injected into and across the gas flow in the throat portion of the venturi, inwardly from the outer wall of the venturi throat, and outwardly from the wall of the hollow structure inside of the throat.
An undesirable charac-teristic of industrially produced gases which are enroute to ultimate venting to atmosphere is that, at times, they are laden with particulate matter and cannot be discharged to the atmosphere because of environmental rulings. At times the particulate size is great enough to permit reliable removal by conventional means which are available to the industry.
It is also necessary to remove particulate matter in the sub-micron and micron size range, which, because of their tiny dimensions (one micron equals 0.0000~ inch) begin to assume atomic/molecular characteristics, and are extremely difficult to remove, to a satisfactory degree from gas by filtration.
In such cases there has been resort to the venturi scrubbers for more complete particulate matter removal from the gases. As the name suggests, the venturi scrubber i9 fundamen-tally based on flow line restriction through area reduction, to a throat section, which is immediately followed by gentle area increase, in an expanding conical section following the throat, to the original line size.
Venturi flow state is used for metering of fluids, because of the flow acceleration in the reduced area throat, versus flow in the line prior to the area reduction.
However, an advantage of the venturi is that the velocity pressure of the flow at the throat is virtually completely converted back to static pressure in the gently expanding section after the throat. In the prior art, the converging section of the venturi has an angle of convergence ge.nerally of the order of 25, and in the expansion section after the throat, the included angle is generally of the order of 7.
Since the gas, and particulate matter carried by it, carry neyative charges, and the liquid injected at the venturi throat is also negatively charged, and since like charges repel, there must be means to overcome the repulsive forces between the particulate matter and the water, to permit wetting of the particulate matter, and the absorption and entrainment of the particulate matter by the liquid, for removal from the gas stream.
If the gas stream and its particulates are moving at great enough velocity at the instance of impact against water, the momentum of the solid particulates is great enough to cause them to be driven into the liquid, and, despite the repulsive effect of like charges, cause wetting absorption of the particulate matter, and removal from the gas stream.
Since it is not desirable to maintain line flow velocity great enough to permit particulate entrapment by liquids, a venturi tube is generally inserted into the gas flow line to achieve great enough gas flow velocity at the restriction throat of the venturi.
However, this higher velocity head must be converted to static pressure head, and this is accomplished by the expanding section of the venturi.
The venturi scrubber is a commonly used apparatus for the removal of particulate matter. However, as it is used in industry, and where the throat restriction becomes rectangular, after the round duct, for maximal gas-liquid contact at the throat restriction, efficiency of particulate removal is typically of the order of 95%. In some cases the 95% efficîency is not acceptable.
The improved venturi scrubber of this invention increases the efficiency of particulate removal from a gas stream to a significantly higher percentage than 95%, by providing two stages and staggered liquid injection means, for significant increase in gas-against-liquid strike, to avoid, as far as possible, the 5% particulate escape from liquid entrapment 2Q or collision, which is the best that the prior art can do.
The invention is an improved venturi scrubber for removing fine particulate matter from a flow of gas in a conduit, comprising:
(a) a venturi inserted into said conduit, comprising a converging section of selected converging angle, a throat, of selected diameter, and a diverging section of selected diverging angle;
~b) a plenum surrounding said venturi in the region upstream and down-stream of said throat, and means to conduct water flow under pressure to said plenum;
(c) a plurality of spaced first orifices, connecting from said plenum, through the wall of said venturi at said throat, whereby high velocity first jets of water will flow inwardly through said orifices into the flowing _ ~ _ 6~
gas in said venturi;
(d) internal hollow s-tructural means inside said venturi, longitudinally-spaced approximately opposite said plenum, said hollow structural means connected to said plenum; said hollow structural means dividing the area of said throat into at least one double-walled space for said gas flow;
(e) a plurality of spaced second orifices in the wall of said hollow structural means, whereby a plurality of high velocity second jets of water will flow from said second orifices outwardly into said at least one double-walled space, for said gas flow;
whereby said first and second orifices will provide, respectively, first and second high velocity jets of water into said at least one double-wailed space, to contact at high velocity said gas in said space, and to remove said particulate matter.
Also new and novel in the art of venturi scrubbing is the combination of injection directions, of the liquid jets, from both the peripheral wall inwardly of the throat, and from the internal portion of the throat outwardly toward the walls of the throat section of the venturi. This is provided for in this invention by both a round or rectangular throat restriction.
It is a primary object of this invention to provide a venturi-type scrubber, which may be either circular or rectangular in cross-section. In one respect it is similar to the prior art scrubbers in that it provides a plenum surrounding the throat portion of the venturi, into which high-pressure water is provided, and from the plenum a plurality of orifices leads through the wall of the throat of the venturi into the interior portion of the throat, providing a first series of high velocity jets of water injected radially inwardly and across into the flowing stream of gas.
In one embodiment of this invention a cylindrical pipe is placed along the axis of the venturi, over a selected region upstream and downstream from the throat. This pipe is connected to the plenum by a radial pipe connection. A plurality of orifices is circumferentially provided in the wall of this axial pipe, in a transverse plane, so that a plurality of high-pressure jets of water flow outwardly radially into the gas stream, which flows through the annular wall of gas, between the central pipe and the internal wall of the venturi. These high velocity jets cause impact mixing between the gas flow and the water so that all of the particulate matter in the high ~elocity - 5a -5~
gas stream is contacted at high velocity by the water stream, and so are wetted and collected by the water and withdrawn from the gas stream. The first jets flowing inwardly from the wall of the venturi are circumferentially spaced by a selected angle A. The second jets flowing outwardly from the central pipe, are circumferentially spaced by -the same angle A, but they are staggered by one half of that angle so that together they cover more completely the full cross-section of the gas flow. Furthermore~ the plane in which the second jets are provided is downstream a selected dimension D from the plane of the first jets, which passes through the throat of the venturi.
A second embodiment involves a square cross-section venturi, and a corresponding plenum, with the first jets at the throat in two opposite walls of the throat. The internal hollow structural means comprises a rectangular cross-section conduit. The wide faces of the conduit are between, and parallel to the two walls of the venturi that contain the first orifices. There are second orifices in the walls of the wide faces. This internal structure is connected to the plenum.
Here again, the flow of gas in the venturi is divided by the internal hollow structural means in one case into a double-walled flow of gas which is an annular wall of gas, and in the rectangular case, is formed into two flows of gas, which are rectangular in cross-section, with water injection on two opposite walls of the gas flow.
Because of the limited flow invasion into a thick ~ . .
stream of yas of a jet of water, -this direct flow, and reverse flow of jets impinging upon opposite faces of the single, or double, flows of gas unimpeded flow of each water jet due to jet plane displacement provides an opportunity for the jets of water to pass completely throuyh the wall of gas, and to impinge onto the opposite walls of the internal structure and the venturi, to splash, and provide further contact between droplets of water and the gas flow. In the case of -the rectangular venturi the plane of the second jets is spaced downstream of the plane of the first jets, by a selected distance D, and are further equally spaced from each other by the same spacing F of the first jets, but the two sets of jets are staggered by a distance F/2 so as to better contact the full cross-section of the gas flow.
A further improvement involves the use of a short cylindrical section at the throat of the venturi, of the same diameter as the throat, in case of the circular venturi, or of the same rectangular dimensions of the throat, of the rectangular cross-section venturi. The dimension of ~he constant cross-section portion, or section, of the venturi is dimensionally greater than D the spacing between the two transverse planes of the first and second jets.
These and other objects and advantages of this invention and a better understanding of the principles and details of the invention will be evident from the following description taken in conjunction with the appended drawings, in which:
Figure 1 illus-trates in vertical cross-section the circular-type venturi construction of this invention.
Figures 2 and 3 show cross-sectional views of Figure 1, respectively, taken at the planes 2-2 and 3-3 of Figure 1.
Figure 4 illustrates a variation of Figure 1, including a short section of constant diameter o~ the throat.
Figures 5 and 6 show in cross-section, in vertical and transverse cross-section, another embodiment of the invention, comprising a venturi of rectangular cross-section.
Referring now to the drawings and, in particular, to Eigure 1, there is shown one embodiment of the invention which involves a venturi of circular cross-section 10, which is inserted into a circular conduit 12 carrying gas flowing in accordance with arrows 44. Joined to the conduit 12 at the transverse plane 13 is the converging section 16 of the venturi, which reduces the cross-section for flow of gas, from that of the conduit 12, to that of the throat of the venturi at the transverse plane 28, where the converging section 16 is joined to the diverging section 18. The diverging section expands the cross-section of the throat -through a gently expanding cone of angle 65, to the original diameter of and is joined to the conduit 12 (not shown) as is well known in the art. I'he angle of convergence of the converging section is ~$~
of -the order of 25, and the angle of divergence of the diverging section is of the order of 7.
Surrounding -the throat portion from a point upstream of, to a point downstream of, the throat 28 is a plenum 20 surrounding the outer conieal surfaces 16 and 18 of the venturi. A pipe 30 serves to provide water at high pressure flowing in accordance with arrow 49 into the plenum space 26.
There is a plurality N of circumferentially~spaced first orifices 38 in the plane of the throat 28 through which water can flow in accordance with arrows 52, to provide first jets of water 48 flowing radially inwardly, as shown in FIGURE 2.
So far the description of the venturi corresponds to that which is known in the prior art.
In this invention, in addition to the inwardly flowing jets of water 48 at the throat of the venturi, there is inserted into the throat cross-section, a hollow structural means 34 which, in FIGURE 1, is shown as an ~0 axial pipe 34 closed at the upstream end 36, and connected by a radial portic>n 32 to the plenum space 26. Thus, the high pressure water flows by arrows 50 into the pipe 32 and to the axial pipe 34. There is an equal plurality N of circumferentially-spaced second orifices 42 in the pipe 34.
These are in a plane which is spaced a selected distance D, 40 downstream of the plane of the ori.fices 38. As shown in FIGURE 3, these second jets that flow through the orifices 42, flow outwardly, indicated by the numeral 56. These are called second jets as opposed to the first jets flowing through the orifices 38 inwardly from the plenum space 26.
The pressure of the water and corresponding velocity of the jets, is such that the high velocity jets will pass through the annular space for gas flow, between the internal structure 34 and the throat wall of the venturi. The velocity is sufficient to carry the jets through the gas and impinge on the opposite wall, causing a splatter, and formation of droplets which further flow turbulently into the gas flow to better contact the particulate matter.
The use of an internal structural means, such as pipe 34 and the conduit 68 of FIGUR~S 5 and 6, serves to break up the full cross-section of the throat for a flow of gas into a shape of cross-section for flow, which comprises an annular wall of gas having an outer and inner surface, which is of smaller transverse dimension than the diameter of the total cross-section of the throat. Similarly, it may be in the form of two rectangular spac-es of gas flow, eaeh of the spaees having walls which are closer spaced to the throat wall than the diameter of maximum spacing of the throat. Thus, the high velocity jets have a better chance to penetrate through the section of ~as flow, at high velocity and, thus, to impinge at high velocity on the particulate matter, sweeping it out of the gas flow. The impingement of -the jets on the opposite metal walls serves further to provide high velocity flow of droplets, to provide a turbulent mixing of high velocity water, of large surface area, and high veloci-ty, with the gas, and, thus, to provide better scrubbing of -the fine particula-te matter from the gas flow.
As shown in Figures 2 and 3, the circumferential spacing or angle A between the first orifices of Figure 2 in the wall of the venturi and the second orifices in the central pipe is preferably the same angle A, and the azimuthal position of the orifices is staggered so that the first jets and second jets will be angularly spaced by an angle A/2, between the adjacent jets. Also, the two-stage injection, where the second jets are injected at a distance D, downstream of the plane of the first jets; and staggered radial positions, makes for a greater opportunity for the water to contact all of the gas flow.
Referring now to Figure 4, there is shown a variation in a portion of the structure of the throat of the ven-turi, in which the throat includes a cylindrical element 60, of selected length 62, the diameter being equal to the throat portion of the venturi of Figure 1. This cylindrical portion 60 joins the converging portion 16 at the plane 28 and is joined to the expanding section 18 at a downstream plane 64. The spacing between the two planes 28 and 64 being a selected dimension 62.
The displacement D between the planes of the first jets 48 and second jets 56 is less than the dimension 62 of the constant diameter portion.
Whlle the con.stant diameter portion, or constant cross-sectional area portion, of the throat shown in Fiyure 4 is illustra~ed as a variation of Figure 1, which is designed for the circular cross-sec-tional venturi, it can be applied equally well -to the rectangular cross-section venturi shown in Figures 5 and 6.
Referring now to Figures 5 and 6, there is shown the throat portion of a venturi scrubber having a conversion section 72 with converging gas flow 70, to the plane of the throa~ 90, where the converging section 72 joins the diverging or expan-ding section 74. As indicated in Figure 4, the throat section could include a short section of constant cross-section, corre-sponding to that of the plane of the throat 90. A plenum 76 is provided as before, whlch is also rectangular in cross-section corresponding to that of the throat 90.
Figure 6 is a view of the throat section taken across the plane 6-6 of Figure 5. Figure 5 is a cross-sectional taken across the plane 5-5 of Figure 6. A high pressure flow of water 80 enters through an inlet pipe 78 into the space 94 of a plenum 76. This flow divides into two parts, one part 86 directed for flow through orifices 98 and providlng jets 88, flowing inwardly. Another part, illustrated by arrows 82, flows into the central hollow space 95 of structure 68 and out through orifices 84, providing jets 85 which flow outwardly into the gas spaces between the inner wall of the venturi and the outer wall of the central hollow structure 68.
As illustrated in Figure 6 the cross-section of the venturi at the throa-t is now divided by the central structure 68 into two rectangular areas 73 and 75 between opposite walls of the venturi throat 90. I'he dimension across these flows through which the jets are directed is less than one half of th~ total dimension of the throat and, therefore, these high velocity jets have a better chance of completely pene-trating the gas wall, from one surface to another, and even to impact on the opposite wall, to splatter and form high velocity droplets. These droplets rebound into the gas flow, and fur-ther tend to wash from the gas the particulate matter. As shown in Figure 6 the second jets 85 are spaced apart a dis-tance F, and are directed in opposition to the first jets 88 which are spaced apart by distance F, and are staggered by the dimension D, which is one half of the spacing F, between jets in each set~ Furthermore, as previously stated, the planes of the second jets 85 are spaced downstream by a selected distance D, from the plane of the first jets, which isin the plane 90 of the throat. Consequently, the staggering of the jets to better cover the full cross-section of the gas flow, and the two-stage injectionr and the narrowing of the dimension of the gas flow through which the water jets must pass, by use of an internal structure, provide a much-improved opportunity for high velo-city mixing of the water jets transversely, into the gas flow, and to better contact the particulate matter, and to cause it to be wetted by the wa-ter, and -to flow ou-t of the gas stream with the water, and be removed therefrom.
While the invention has been described with a certain degree of particularity, i-t is manifest that many changes may be made in the details of construction ahd the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for the purposes of exempli:Eicati.on, but is to be limited only by the scope of the attached clai~s, including the full range of equivalency to which each element thereof is entitled.
Claims (16)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An improved venturi scrubber for removing fine parti-culate matter from a flow of gas in a conduit, comprising:
(a) a venturi inserted into said conduit, comprising a converging section of selected converging angle, a throat, of selected diameter, and a diverging section of selected diverging angle;
(b) a plenum surrounding said venturi in the region upstream and downstream of said throat, and means to conduct water flow under pressure to said plenum;
(c) a plurality of first orifices, connecting from said plenum, through the wall of said venturi at said throat, whereby high velocity first jets of water will flow inwardly through said orifices into the flowing gas in said venturi;
(d) internal hollow structural means inside said ven-turi, longitudinally-spaced approximately opposite said plenum, said hollow structural means connected to said plenum; said hollow structural means dividing the area of said throat into at least one double-walled space for said gas flow;
(e) a plurality of second orifices in the wall of said hollow structural means, whereby a plurality of high velocity second jets of water will flow from said second orifices outwardly into said at least one double-walled space, for said gas flow;
whereby said first and second orifices will provide, respectively, first and second high velocity jets of water into said at least one double-walled space, to contact at high velocity said gas in said space, and to remove said particulate matter.
(a) a venturi inserted into said conduit, comprising a converging section of selected converging angle, a throat, of selected diameter, and a diverging section of selected diverging angle;
(b) a plenum surrounding said venturi in the region upstream and downstream of said throat, and means to conduct water flow under pressure to said plenum;
(c) a plurality of first orifices, connecting from said plenum, through the wall of said venturi at said throat, whereby high velocity first jets of water will flow inwardly through said orifices into the flowing gas in said venturi;
(d) internal hollow structural means inside said ven-turi, longitudinally-spaced approximately opposite said plenum, said hollow structural means connected to said plenum; said hollow structural means dividing the area of said throat into at least one double-walled space for said gas flow;
(e) a plurality of second orifices in the wall of said hollow structural means, whereby a plurality of high velocity second jets of water will flow from said second orifices outwardly into said at least one double-walled space, for said gas flow;
whereby said first and second orifices will provide, respectively, first and second high velocity jets of water into said at least one double-walled space, to contact at high velocity said gas in said space, and to remove said particulate matter.
2. The venturi scrubber as in claim 1 in which said venturi is circular in cross-section.
3. The venturi scrubber as in claim 1 in which said venturi is rectangular in cross-section.
4. The venturi scrubber as in claim 2 in which said internal hollow structural means comrpises axial pipe means, said at least one double-walled space comprises the annular space between said axial pipe and said throat, said first and second jets being injected into said annular space through opposite walls of said double-walled gas flow.
5. The venturi scrubber as in claim 4 in which the numbers of first orifices and second orifices are equal, and equiangularly spaced.
6. The venturi scrubber as in claim 5, in which the angular orientation of said first and second jets are spaced by an angle equal to one half of the angle between said first jets.
7. The venturi scrubber as in claim 4 in which said second orifices lie in a transverse plane, spaced downstream of said gas flow, from the transverse plane of said first orifices, by a selected dimension D.
8. The venturi scrubber as in claim 3, in which said internal hollow structure means comprises a conduit of rect-angular cross-section extending between and through opposite walls of said venturi, the transverse width of said rectangular conduit being a selected dimension, said rectangular conduit positioned approximately in the center of said throat, and forming two substantially similar rectangular double-walled spaces for gas flow, a plurality of spaced second orifices in the two side walls of said rectangular conduit, facing two walls of said venturi containing said first orifices, whereby first and second high velocity jets of water will flow in opposite directions into each wall of said double-walled rectangular spaces.
9. The venturi scrubber as in claim 8 in which said second orifices are in a transverse plane spaced downstream of the plane of said first orifices by a selected dimension D.
10. The venturi scrubber as in claim 9 in which the spacing between said first orifices is the same as between said second orifices, and equal to a dimension F.
11. The venturi scrubber as in claim 10 in which the positions of said first orifices are staggered with respect to the position of said second orifices by a dimension F/2 whereby said first and second jets are spaced laterally, and downstream, from each other.
12. The venturi scrubber as in claim 1, in which said throat is the plane of intersection of said converging and diverging portions.
13. The venturi scrubber as in claim 1, in which said throat includes a short cylindrical section, joined at its upstream end to said converging section, and at its downstream end to said diverging section.
14. The venturi scrubber as in claim 13 in which the length of said cylindrical section is greater than its diameter.
15. The venturi scrubber as in claim 1 in which the angle of convergence of said converging section is of the order of 25?.
16. The venturi scrubber as in claim 1, in which the angle of divergence of said diverging section is of the order of 7°.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US81935877A | 1977-07-27 | 1977-07-27 | |
| US819,358 | 1992-01-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1116509A true CA1116509A (en) | 1982-01-19 |
Family
ID=25227930
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000307444A Expired CA1116509A (en) | 1977-07-27 | 1978-07-14 | Venturi scrubber |
Country Status (7)
| Country | Link |
|---|---|
| JP (2) | JPS5426066A (en) |
| CA (1) | CA1116509A (en) |
| DE (1) | DE2832837A1 (en) |
| FR (1) | FR2398534B1 (en) |
| GB (1) | GB2001549B (en) |
| IT (1) | IT1105928B (en) |
| NL (1) | NL7807370A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE202009019074U1 (en) * | 2009-11-24 | 2016-05-23 | J. Schmalz Gmbh | Compressed air operated vacuum generator |
| CN109499231B (en) * | 2019-01-14 | 2023-12-01 | 询莱流体设备(太仓)有限公司 | Venturi scrubber with changeable structure |
| CN109529755B (en) * | 2019-02-01 | 2024-07-02 | 大连海事大学 | Multi-suction reinforced mixing Venturi reactor |
| WO2022094048A2 (en) * | 2020-10-30 | 2022-05-05 | Norton Engineering Consultants, Inc. | Compact venturi scrubber and method to treat gas streams utilizing the compact venturi scrubber |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE498107A (en) * | 1946-11-08 | |||
| DE1277816B (en) * | 1956-08-27 | 1968-09-19 | Babcock & Wilcox Company Und C | Venturi tube for washing gases with a viscous liquid |
| US2913232A (en) * | 1956-08-29 | 1959-11-17 | Cottrell Res Inc | Gas treating device |
| US3085793A (en) * | 1960-10-26 | 1963-04-16 | Chemical Construction Corp | Apparatus for scrubbing solids from gas streams |
| US3582050A (en) * | 1968-09-27 | 1971-06-01 | Nat Steel Corp | Fluid-handling,gas-scrubbing,and blast furnace top pressure control |
| US3898308A (en) * | 1972-08-29 | 1975-08-05 | Baum Verfahrenstechnik | Venturi scrubber |
-
1978
- 1978-06-28 GB GB787828199A patent/GB2001549B/en not_active Expired
- 1978-07-07 NL NL7807370A patent/NL7807370A/en not_active Application Discontinuation
- 1978-07-14 CA CA000307444A patent/CA1116509A/en not_active Expired
- 1978-07-25 IT IT50453/78A patent/IT1105928B/en active
- 1978-07-26 JP JP9139578A patent/JPS5426066A/en active Pending
- 1978-07-26 FR FR7822141A patent/FR2398534B1/en not_active Expired
- 1978-07-26 DE DE19782832837 patent/DE2832837A1/en not_active Withdrawn
-
1982
- 1982-04-12 JP JP1982052981U patent/JPS5912991Y2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2001549B (en) | 1982-01-20 |
| IT7850453A0 (en) | 1978-07-25 |
| DE2832837A1 (en) | 1979-02-15 |
| IT1105928B (en) | 1985-11-11 |
| JPS5912991Y2 (en) | 1984-04-18 |
| JPS5426066A (en) | 1979-02-27 |
| NL7807370A (en) | 1979-01-30 |
| FR2398534B1 (en) | 1985-10-18 |
| FR2398534A1 (en) | 1979-02-23 |
| JPS58156520U (en) | 1983-10-19 |
| GB2001549A (en) | 1979-02-07 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |