EP0137955A2 - Verfahren und Vorrichtung zum Mischen von Fluiden - Google Patents

Verfahren und Vorrichtung zum Mischen von Fluiden Download PDF

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Publication number
EP0137955A2
EP0137955A2 EP84109688A EP84109688A EP0137955A2 EP 0137955 A2 EP0137955 A2 EP 0137955A2 EP 84109688 A EP84109688 A EP 84109688A EP 84109688 A EP84109688 A EP 84109688A EP 0137955 A2 EP0137955 A2 EP 0137955A2
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EP
European Patent Office
Prior art keywords
fluid
channel
elongate elements
flow
spikes
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.)
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Application number
EP84109688A
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English (en)
French (fr)
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EP0137955A3 (de
Inventor
John R. Weske
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Individual
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Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0137955A2 publication Critical patent/EP0137955A2/de
Publication of EP0137955A3 publication Critical patent/EP0137955A3/de
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/20—Mixing gases with liquids
    • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
    • B01F23/233—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements
    • B01F23/2334—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements provided with stationary guiding means surrounding at least partially the stirrer
    • B01F23/23341—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements provided with stationary guiding means surrounding at least partially the stirrer with tubes surrounding the stirrer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/30—Injector mixers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F33/00—Other mixers; Mixing plants; Combinations of mixers
    • B01F33/50—Movable or transportable mixing devices or plants
    • B01F33/503—Floating mixing devices

Definitions

  • This invention relates to the art of mixing fluids; particularly, the art of mixing a gas with a liquid.
  • the invention relates to the art of aeration of a liquid.
  • U.S. Patent 3,853,271 (Freshour et al).
  • This system includes a plurality of cup-shaped members. A fluid flows through the central portions of the members, and a low pressure area is developed in the fast-flowing fluid so that air is pulled in from the exterior of the cups to mix with the flowing fluid.
  • U.S. Patent 4,017,565 (Muller).
  • This patent shows a system for mixing a gas with a liquid wherein a pump circulates a liquid in a container. The liquid is pumped through a cylindrically symmetric baffle which provides an annular constriction for increasing the velocity of the circulating liquid. This increased velocity creates the venturi effect whereby air from a tube aligned with the axis of the baffle is admitted to the flowing liquid.
  • U.S. Patent 4,259,267 shows an apparatus wherein a single propeller is located in a fluid beneath a plurality of vertical, cylindrical tubes. As the propeller pulls the fluid through the tubes, a vortex develops in each tube thus entraining gas into the center of each vortex.
  • U.S. Patent 3,643,403 shows an apparatus wherein air is pumped to a disperser located in the body of the fluid. An impeller is located above the disperser and circulates fluid so that bubbles which are emitted from the disperser flow downwardly with the fluid flow to thereby increase the time of contact of the bubbles with the fluid.
  • U.S. Patent 2,479,403 shows a system wherein aeration of sewage is effected by the action of a submerged water-jet injector.
  • British Patent 1,484,657 shows a system wherein air is injected under pressure into a downwardly flowing stream so that the contact time of air bubbles with the fluid is increased.
  • the common faucet aerator is also known wherein flowing water is caused to be turbulent so that air is drawn in by a process similar to the venturi effect.
  • U.S. Patent 4,214,702 shows such a faucet aerator.
  • Another aerator shown in U.S. Patent 2,295,391 (Derden, Jr.) uses a pump to circulate fluid between a container and a chamber containing a gas. The fluid flows through a series of openings into the chamber resulting in a turbulent mixing of the fluid with the gas.
  • Apparatus known in the prior art suffer from several disadvantages.
  • They have a low efficiency. That is, a large power input is required to cause a mixing of the air. Efficiency is typically measured in units of kilograms of oxygen transferred per kilowatt hour of input energy.
  • the prior art apparatus are complex and require structures which are expensive to produce and to maintain.
  • the invention is a method and apparatus wherein a plurality of spike-like elements are used to mix two fluid substances, preferably a gas with a flowing liquid, in a highly simple and efficient manner.
  • the spikes are caused to have motion relative to a fluid, and the spike extends at an angle which is transverse to the direction of flow of the fluid. This produces a low-pressure area on the lee, or downstream, side of the spike, and a gas is admitted to this low pressure area.
  • the low pressure area is created since the flow past an immersed blunt body separates from the body and a region of low-speed flow forms immediately downstream of the body. This low-speed region is bounded on both sides by high speed flow.
  • the bubble will be carried with the flow of the fluid and will dissolve into the liquid.
  • the process is continuous so that a series of bubbles is continuously formed and entrained in the flowing fluid.
  • the admitted gas is air
  • about five percent of the oxygen contained in the air is transferred to liquid water. Transfer of oxygen across the air-water interface continues as long as the bubbles are in contact with the fluid and the rate depends upon the relative concentrations. Of course, other constituents of the air bubble also pass across the air-water interface.
  • the above-described process is very simple and requires very few moving parts.
  • the spike may be placed in a naturally flowing stream, such as in a river or in the outflow of a dam.
  • a pump may be used to circulate the fluid from a stationary pond over the spike to produce aeration.
  • the air introduced by a single spike may be relatively small and, in the preferred embodiment, structures which employ a plurality of spikes are preferred. These structures are easy to produce, are relatively inexpensive and are quite efficient.
  • the spikes are provided in parallel rows, and fluid is passed over the spikes.
  • the spikes extend outwardly from a central body which is rotated in a stationary fluid.
  • a spike 2 is located in a stream of flowing liquid 4.
  • a low pressure develops in the downstream, or lee, portion 6 of the spike 4.
  • a gas (such as air) is drawn into the fluid at the low pressure area 6 since the hydrostatic pressure in the area 6 is less than the pressure of the gaseous region 8 adjacent the flowing liquid 4.
  • the direction of flow of fluid 4 is indicated by arrow 10 and it will be appreciated that since the spike 2 is transverse to the direction of flow, there will be a component of the flow velocity normal to the spike and a component along the spike.
  • the component of flow normal to the spike causes the development of the low pressure area 6, and the component of the flow along the spike causes the air which has been drawn into the low pressure area to move along the spike.
  • the air moves along the spike, it forms bubbles 12, and these bubbles are swept off the end of the spike and into the flowing liquid 4. While the bubbles are carried along by the liquid, transfer of the gas which forms the bubble takes place across the gas-liquid interface as dictated by the concentration gradient.
  • Figure lb shows a cross section of the spike 2 taken along the line lb-lb of figure la. This illustrates how the liquid 4 flows around the spike and creates a low pressure area 6.
  • a preferred form of the spike is shown in plan view in figure lc.
  • the spike shown there is longer than it is wide, the preferred ratio being about 5:1, and it narrows to a point 14.
  • This preferred shape of the spike 2 allows the bubbles to be easily discharged from the end of the spike.
  • the spike is preferably about one inch in length or longer.
  • Figure 2a shows an embodiment wherein fluid 4 flows downwardly through a channel 16.
  • the channel may be a variety of shapes, but preferably has at least two side walls which are parallel.
  • a first array 18 of spikes is placed on one side of the channel, and a second array 20 is placed on an opposed side of the channel.
  • the spikes extend in a plurality of parallel directions.
  • the spikes extend outwardly from the channel so that they form an angle of 30 to 45 degrees with the direction 10 of the flow of the liquid. This angle is preferably 35 to 36 degrees.
  • a first manifold 22 allows the passage of gas therethrough, and a passage 24 in the channel 16 allows the manifold 22 to communicate with the lee side of each of the spikes in array 18.
  • a similar manifold 26 is located on the opposed side of the channel 16 and communicates with the lee side of the spikes in the array 20 by way of passage 28.
  • the manifolds 22 and 26 may be connected to a common source of gas.
  • the downward velocity of flow of the fluid is preferably greater than the upward velocity of the bubbles whereby the bubbles are carried into the liquid 4. This provides contact between the air in the bubbles and the fluid for a substantial period of time and thus allows the gas to pass through the air-liquid interface and into the fluid 4.
  • Figure 2b shows a cross section taken along line 2b-2b of figure 2a.
  • the plurality of spikes 2 in each array can be seen from this figure. It is also seen how a plurality of passages 24 and 28 provide communication with each of the spikes so that air is drawn into the lee side of each spike and each spike forms bubbles as described with respect to figure la.
  • the spikes are preferably slightly curved in the cross-section transverse to their length to present a convex face to the upstream side of the flowing liquid, and a concave face to the downstream side. They are preferably flat at their tips.
  • FIG 3a shows a modification of the apparatus described in figure 2a.
  • the spike arrays used in figure 3a provide a plurality of spikes at different angles to increase the rate of bubble formation.
  • a first array 30 is placed on one side of the channel 16 and a second array 32 is placed on an opposite side. Some of the spikes are located at a first angle with respect to the direction of flow 10 of the liquid and other spikes are located at a different angle.
  • This arrangement provides twice as many spikes as in the embodiment shown in figures 2a and 2b, and the angles at which the spikes extend into the flow are such that efficient operation of the apparatus for each spike array is maintained. That is, the arrays form an angle with the direction of flow of between 30 and 45 degrees.
  • Figure 3b shows how the spikes 2 are interleaved to provide an increased number of spikes, thus providing increased efficiency.
  • the flow of fluid 4 may be provided by any known means.
  • a pump may raise a fluid from a tank and direct it through the channel 16.
  • the channel 16 may be placed in a naturally flowing stream, such as an outlet from a dam so that water will fall by the force of gravity through the channel 16 and become aerated.
  • FIGS. 4a, 4b, 5a, 5b, and 6 show a rotational embodiment of the invention which employs the principles described above.
  • An axially symmetric body 34 is mounted to a shaft 36 for rotation.
  • the shaft 36 is rotated, for example, by a motor 38.
  • a plurality of spikes 2 is attached to the perimeter of body 34 at equal spacings and extend outwardly therefrom.
  • the spikes also slant downwardly at an angle of about 45 degrees with respect to the axis of rotation.
  • the spikes are curved backwardly with respect to the direction of rotation of the body 34 so that a tangent of the curved spike at any point forms an angle of 30 - 45 degrees with the tangent of a circle through that point and concentric with body 34.
  • a collar 40 is mounted for rotation with the body 34 and provides an open channel for gas to be admitted to the lee side of each of the spikes 2.
  • the rotational embodiments provide spikes in series, whereas the other embodiments provide spikes in parallel.
  • liquid is displaced toward the tips of the spikes by centrifugal force.
  • gas flows into the lee side of each spike.
  • Liquid is also.pulled into the spaces between the spikes from above and below the spikes. This creates two toroidal systems of circulation as indicated by arrows C in figure 4a.
  • Bubbles are formed and are swept into the stream of circulating water until they rise to the surface of the liquid.
  • the gaseous constituents of the bubbles pass through the gas-liquid interface as a function of contact time and relative concentrations.
  • the rotational embodiment is capable of producing a reduction in pressure, measured in inches of water, which is approximately equal to the velocity head of the tips of the spikes. For example, in one test a tip velocity of about 4 feet per second produced a pressure reduction of about 3 inches of water.
  • the rotor may be immersed in a tank. This would be useful if it were desired to aerate a deep tank by placing the rotor near the bottom of the tank and connecting the collar to a high-pressure hose.
  • Figure 4b shows a view taken along line 4b-4b of figure 4a. This figure shows how the spikes 2 are curved to provide the angular relationship with respect to the fluid 4 which was described above with respect to figure la: that is, the fluid preferably meets the spike at 30 - 45 degrees. As the body 34 rotates, there will be relative motion between the spikes 2 and the fluid 4, and the low pressure area 6 will develop. Gas will then be drawn in through the collar 40 and into the fluid.
  • Figure 5a shows a spike rotor wherein two rows of spikes 2 extend from the rotating body 34 at different angles. This doubles the number of spikes mounted to the body 34 and thus increases the efficiency of aeration since the number of sources is doubled without a correspondingly large increase in the required input power.
  • Figure 5b shows a plan view of the embodiment shown in figure 5a and shows the interleaving of the spikes 2.
  • FIG 6 shows an embodiment similar to that shown in figure 4a, but wherein an impeller is combined with body 34.
  • the spikes 2 serve to entrain air bubbles into a downwardly flowing stream, and the impeller conveys this stream to a greater depth by adding a downward velocity. This increased downward velocity prolongs the time of contact of the bubbles 12 with the fluid 4 to increase the amount of gas which is dissolved into the fluid 4.
  • An impeller 42 is connected to the shaft 36 below the rotating body 34 so that impeller 42 rotates with body 34.
  • the impeller includes a plurality of impeller blades 44 which receive fluid flow from the spikes 2, and rotating impeller blades 44 causes the fluid 4 and the entrained bubbles 12 to continue their flow downwardly and outwardly after leaving spikes 2.
  • the impeller is advantageous because it is more efficient at only pumping fluid than are the spikes.
  • FIG. 7a shows another practical embodiment of the invention. This embodiment is useful for aeration of a pond, and it employs a floating structure 46.
  • a first cylindrical duct 48 is supported by flotation elements 50 which causes the entire structure 46 to float.
  • a motor 52 is secured to a mount 54 which is in turn secured to the duct 48 and flotation elements 50 so that it rigidly supports motor 52.
  • a shaft 56 extends downwardly from the motor 52 and is connected to a pump impeller 58.
  • a second duct 60 is attached to the floatation structure and extends downwardly from the pump impeller to direct fluid 4 from the lake or pond to the impeller 58.
  • the cylindrical duct 48 is surrounded by a third duct 62, and the upper edge of duct 48 is below an upper edge of the duct 62.
  • the pump impeller 58 draws water in through the duct 60 and creates a body of water 64 which has an upper surface 66 which is above the upper surface 68 of the pond 4.
  • a channel 70 through which fluid falls due to the fact that upper surface 66 is above upper surface 68.
  • a plurality of spike arrays 72 are located in the channel 70 to cause aeration in accordance with the principles described above in connection with figure la.
  • Tubes 74 provide an air channel to supply the spike arrays 72 with air.
  • Figure 7b shows a view taken along line 7b-7b of figure 7a and the spike arrays 72 are more clearly visible in this figure. Also, a manifold 76 connected to tubes 72 is more clearly shown. This manifold 76 may be formed as a part of duct 62 or may be a separate element.
  • FIG. 7c is a cross section taken along line 7c-7c of figure 7a and shows how the spike arrays 72 are arranged.
  • Each of the spike arrays 72 comprises a plurality of spikes 2 which are similar to those described above with respect to the other embodiments.
  • the spikes are attached to peaked manifolds 78 which communicate with manifold 76.
  • Each manifold 78 is mounted to a channel-defining plate 79 which extends between ducts 48 and 62.
  • Passages 80 permit the interiors of the manifolds 78 to communicate with the low pressure areas on the lee side of the spikes 2 whereby air will be drawn in through the tubes 74, the manifold 76, the manifold 78, and into the flowing fluid 4. Bubbles 12 are formed and are dispersed into the fluid 4 for gasification or aeration of the fluid.
  • the embodiment shown in figures 7a through 7c may float in a pond and may be anchored to the floor of the pond or to the shore.
  • Figure 8 shows an embodiment which is adapted to be mounted in a body of liquid 4.
  • This embodiment employs a motor 80 to drive a shaft 82 which, in turn, rotates a pump impeller 84.
  • An inner cylindrical body 86 has a shaft 82 passing therethrough.
  • An outer cylindrical body 88 surrounds the body 86 and is rotationally fixed thereto to form an annular channel 90 between the inner and outer bodies.
  • a first conical array 92 of spikes is connected to an inner surface outer body 88 and a second conical array 94 of spikes is connected to an outer surface of the inner body 86.
  • the arrays preferably extend completely along the annular channel 90.
  • Tubes 98 are attached to outer body 88 and communicate with a manifold 100 which is shown integral with the outer body. The manifold may be separate from the body. Manifold 100 is located in the upper edge of the outer body 88 and a plurality of passages 102 communicate with the lee side of each of the spikes in the array 92 so that as fluid flows through the channel 90, air is drawn in through the tubes 98 and is mixed with the fluid 4.
  • Tubes 104 communicate with the interior of inner cylindrical body 86 and a plurality of passages 106 allow air which is drawn in through the tubes 104 to communicate with the lee side of each of the spikes in array 94.
  • Figure 9 shows an embodiment which is useful for a flowing stream.
  • a box 106 is open at a first, upstream end (not shown), and closed at a second, downstream end 108; the direction of flow is shown by the arrow.
  • a channel 110 is formed between an upstanding edge 112 and the downstream end 108 of the box.
  • An outlet channel is formed by portions 109 and 113.
  • the box 106 may rest on the bottom 114 of a stream or may alternatively be secured in some other manner, such as by anchoring the box to the shore of the stream.
  • the upstanding edge 112 and the downstream end 108 each have a manifold 116 therein which communicates with a tube 118.
  • a first spike array 120 extends outwardly from the upstanding edge 112, and a second spike array 122 extends outwardly from the downstream end 108.
  • the box 106 is placed in a stream so that it fills with fluid 4 such that the upper surface 124 of the fluid in the box is above the upper surface 126 of the fluid 4 in the river.
  • the hydrostatic head created by this difference in height between surface 124 and surface 126 causes fluid to flow through the channel 110 thus creating low pressure areas on the lee side of the spikes in the arrays 120, 122 and thus drawing air through the tubes 118 and manifolds 116 as described above with respect to the other embodiments. Bubbles 12 are drawn off the spikes 2 in the arrays 120, 122, thus aerating the flowing stream.
  • Figure 10 shows an embodiment whereby a cascade arrangement permits an efficient use of a natural drop in a stream or the full head created by a pump.
  • a first dam 128 is placed in a flowing stream 4 and a first array of spikes 130 extends outwardly from the dam 128.
  • a manifold is formed along an upstream face of the dam 128 by plate 132 and adjacent portions of dam 128.
  • the spike array 130 communicates with the manifold, and a tube 134 communicates with the manifold to supply fresh air thereto.
  • each dam 128, 128' and 128" is arranged so that a hydrostatic head 135 is developed between the surface level of the fluid behind each of the dams and the level downstream of the dam.
  • a hydrostatic head 135 is developed between the surface level of the fluid behind each of the dams and the level downstream of the dam.
  • the arrangement shown in figure 10 also illustrates a U-shaped channel formed between the streambed 136 and the lower portion of the dam 128.
  • This arrangement provides increased contact time of the bubbles 12 with the fluid 4 as the fluid flows under the bottom portion 138 of the dam 128.
  • This arrangement is quite efficient since it employs a syphon-like process to draw the fluid along the extended channel between the stream bed and the dam 128.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Aeration Devices For Treatment Of Activated Polluted Sludge (AREA)
EP84109688A 1983-08-16 1984-08-14 Verfahren und Vorrichtung zum Mischen von Fluiden Withdrawn EP0137955A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US52379683A 1983-08-16 1983-08-16
US523796 1983-08-16

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EP0137955A2 true EP0137955A2 (de) 1985-04-24
EP0137955A3 EP0137955A3 (de) 1987-06-16

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2255513A (en) * 1987-11-04 1992-11-11 Barrett Haentjens & Co Gas absorption in a liquid

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2295391A (en) * 1939-12-28 1942-09-08 Jr Augustus C Durdin Sewage treatment apparatus
US4271099A (en) * 1979-10-01 1981-06-02 Kukla Thomas S Apparatus for thorough mixture of a liquid with a gas
EP0031166A1 (de) * 1979-12-21 1981-07-01 Grünzweig + Hartmann und Glasfaser AG Verfahren zur Herstellung von Wärmeisolierkörpern sowie Vorrichtung zur Durchführung des Verfahrens
AT371373B (de) * 1981-06-09 1983-06-27 Huetter Karl Vorrichtung zum belueften von stroemenden medien

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2295391A (en) * 1939-12-28 1942-09-08 Jr Augustus C Durdin Sewage treatment apparatus
US4271099A (en) * 1979-10-01 1981-06-02 Kukla Thomas S Apparatus for thorough mixture of a liquid with a gas
EP0031166A1 (de) * 1979-12-21 1981-07-01 Grünzweig + Hartmann und Glasfaser AG Verfahren zur Herstellung von Wärmeisolierkörpern sowie Vorrichtung zur Durchführung des Verfahrens
AT371373B (de) * 1981-06-09 1983-06-27 Huetter Karl Vorrichtung zum belueften von stroemenden medien

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2255513A (en) * 1987-11-04 1992-11-11 Barrett Haentjens & Co Gas absorption in a liquid
GB2255513B (en) * 1987-11-04 1995-05-31 Barrett Haentjens & Co Method for effecting absorption of a fluid in another fluid and apparatus for effecting gas absorption in a liquid

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