GB2059790A - Apparatus for combining a liquid and a gas - Google Patents

Apparatus for combining a liquid and a gas Download PDF

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Publication number
GB2059790A
GB2059790A GB8030484A GB8030484A GB2059790A GB 2059790 A GB2059790 A GB 2059790A GB 8030484 A GB8030484 A GB 8030484A GB 8030484 A GB8030484 A GB 8030484A GB 2059790 A GB2059790 A GB 2059790A
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GB
United Kingdom
Prior art keywords
liquid
metres
depth
tank
nozzle
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.)
Granted
Application number
GB8030484A
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GB2059790B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Serck Industries Ltd
Original Assignee
Serck Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Serck Industries Ltd filed Critical Serck Industries Ltd
Priority to GB8030484A priority Critical patent/GB2059790B/en
Publication of GB2059790A publication Critical patent/GB2059790A/en
Application granted granted Critical
Publication of GB2059790B publication Critical patent/GB2059790B/en
Expired legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/02—Aerobic processes
    • C02F3/12—Activated sludge processes
    • C02F3/1278—Provisions for mixing or aeration of the mixed liquor
    • C02F3/1294—"Venturi" aeration means
    • 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
    • B01F23/232—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using flow-mixing means for introducing the gases, e.g. baffles
    • B01F23/2323—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using flow-mixing means for introducing the gases, e.g. baffles by circulating the flow in guiding constructions or conduits
    • B01F23/23231—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using flow-mixing means for introducing the gases, e.g. baffles by circulating the flow in guiding constructions or conduits being at least partially immersed in the liquid, e.g. in a closed circuit
    • 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
    • B01F23/40—Mixing liquids with liquids; Emulsifying
    • B01F23/45—Mixing liquids with liquids; Emulsifying using flow mixing
    • B01F23/454—Mixing liquids with liquids; Emulsifying using flow mixing by injecting a mixture of liquid and gas
    • 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
    • B01F25/20—Jet mixers, i.e. mixers using high-speed fluid streams
    • B01F25/21—Jet mixers, i.e. mixers using high-speed fluid streams with submerged injectors, e.g. nozzles, for injecting high-pressure jets into a large volume or into mixing chambers
    • 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
    • B01F25/31—Injector mixers in conduits or tubes through which the main component flows
    • B01F25/314—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced at the circumference of the conduit
    • B01F25/3141—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced at the circumference of the conduit with additional mixing means other than injector mixers
    • 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
    • B01F25/31—Injector mixers in conduits or tubes through which the main component flows
    • B01F25/314—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced at the circumference of the conduit
    • B01F25/3143—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced at the circumference of the conduit characterised by the specific design of the injector
    • B01F25/31432—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced at the circumference of the conduit characterised by the specific design of the injector being a slit extending in the circumferential direction only
    • 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
    • B01F25/50—Circulation mixers, e.g. wherein at least part of the mixture is discharged from and reintroduced into a receptacle
    • B01F25/53—Circulation mixers, e.g. wherein at least part of the mixture is discharged from and reintroduced into a receptacle in which the mixture is discharged from and reintroduced into a receptacle through a recirculation tube, into which an additional component is introduced
    • 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
    • B01F25/50—Circulation mixers, e.g. wherein at least part of the mixture is discharged from and reintroduced into a receptacle
    • B01F25/54—Circulation mixers, e.g. wherein at least part of the mixture is discharged from and reintroduced into a receptacle provided with a pump inside the receptacle to recirculate the material within the receptacle
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/02—Aerobic processes
    • C02F3/12—Activated sludge processes
    • C02F3/22—Activated sludge processes using circulation pipes
    • C02F3/226—"Deep shaft" processes
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

Abstract

An apparatus for combining a liquid and a gas includes a pump 12 for circulating the liquid in tank 10 which includes means 11 for maintaining a constant liquid depth d, liquid from the pump 12 being delivered to the nozzle 1 of an injector pump 17 having a gas inlet 23, the gas liquid mixture being returned to the tank 10 by a mixing pipe 20. The cross-sectional area Am of the mixing pipe 20 and the cross-sectional area An of the nozzle 1 6 are selected so that the ratio Am/An lies between 1.5 and 12, the upper limit of this ratio decreasing with an increase in the liquid depth d from 2 to 8 metres. <IMAGE>

Description

SPECIFICATION Apparatus for combining liquids and gases This invention relates to apparatus for combining liquids and gases.
It is known from U.S. Patent 1808956 and British Patent 1484657 to provide an appa ratus for combining a liquid and a gase, the apparatus including a circulating pump for withdrawing the liquid from a tank, and an injector pump having a nozzle through which the liquid is directed by the circulating pump, together with an inlet for gas which is entrained by the liquid as it leaves the injector pump nozzle. The injector pump outlet communicates with a mixer pipe for re-introducing the liquid into the tank adjacent the bottom thereof, so that gase bubbles entrained in the liquid may float upwardly within the tank.
It is advantageous, particularly in the use of such an apparatus for the aerobic treatment of sewage, that the rate of oxygen absorption by the liquid shall be a maximum for any given value of the energy input to the apparatus, whether this energy input is provided by a circulating pump, as shown in the above references, by means of the flow of liquid under the influence of an independently-provided elevation head, or by other suitable means. The rate of oxygen absorption is commonly expressed as oxygenation efficiency, in kilograms of oxygen per kilowatt hour of energy input. It has been found that this efficiency is dependent, inter alia, on the ratio of the cross sectional area of the mixer pipe to that of the injector pump nozzle having regard to the depth of the liquid in the tank, the values of said ratio generally decreasing as liquid depth increases.
It is an object of the present invention to provide an apparatus for combining gases and liquids, the apparatus having a high oxygenation efficiency.
According to the invention an apparatus for combining a liquid and a gas comprises a tank for containing the liquid, means for maintaining a substantially constant predetermined depth of liquid in said tank, an injector pump having a nozzle for discharging liquid, an inlet through which gas can be drawn as a result of passage of liquid through said nozzle, and an outlet, means for supplying a liquid under pressure to said injector pump nozzle, a mixing pipe communicating with said injector pump outlet and extending therefrom to a position adjacent the bottom of said tank, and a deflector for urging a gas-liquid stream leaving said mixing pipe in a direction transverse to the axis thereof, the cross sectional area (Am) of said mixing pipe and the cross sectional area (An) of said nozzle being selected so that the ration Am/An is between 1.5 and 12, the upper limit of this ratio decreasing with increase in said predetermined depth between 2 and 8 metres.
An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawing in which: Figure 1 shows, diagrammatically, an apparatus for the aeration of sewage, and Figure 2 is a graph of a plurality of values of the ratio Am/An, plotted against a plurality of predetermined liquid depths.
As shown in the drawing a tank 10 has an open top and is provided with a weir 11 so that a liquid within the tank 10 may be maintained at a constant level. Within the tank 10 is a low-head centrifugal circulating pump 12 driven by an electric motor 13 and supported on an intake pipe 14. A delivery pipe 15 of the pump 12 allows the liquid to be delivered to a manifold in the form of an open trough 16, the liquid in the trough 16 passing to a plurality of liquid injector pumps 17, only one of which is shown.
Each injector pump 17 is, as shown, adjacent the liquid surface and has a circular nozzle 18 communicating with the manifold 16 and an outlet 19 which is axially aligned with, and spaced from, the nozzle 18. The outlet 19 communicates with a vertical mixing pipe 20 by way of frusto-conical diffuser portion 21. The mixing pipe 20 extends to a position adjacent the bottom of the tank 10 and is provided with a deflector 21 which urges a gas liquid flow within the pipe 20 to leave the latter in directions generally radially horizontally along the bottom of the tank 10.
The injector pump 17 includes an air inlet 23 which communicates with the gap between the nozzle 18 and the outlet 1 9, so that passage of liquid through the nozzle 18 causes air to be drawn, in a known manner, through the inlet 23 and entrained in the liquid passing to the outlet 19.
The cross-sectional area Am of the bore of the mixing pipe 20 is between 1.5 and 12 times the cross-sectional area An of the nozzle 18, the value Am/An being selected in accordance with the depth d of liquid in the tank 10, maximum values of the ratio Am/An decreasing with increased depths of liquid.
For example, with a liquid depth d of 2 metres, values Am/An of 8 and 4 both give oxygenation efficiencies of between 3.5 and 4 kilograms of oxygen per kilowatt hour. Increasing the liquid depth d to 4 metres has been found to result in a drop in oxygenation efficiency when Am/An = 8, but an increase in oxygenation efficiency when Am/An = 4.
Experimental results indicate that for liquid depths of 8 metres values of Am/An between 5.5 and 1.5 will provide oxygenation efficiency of at least 3.5. Experimental results also show that at liquid depths of 1.5 metres the value Am/An is less critical, and that values between 1.5 and 12 are satisfactory, but that the higher values of Am/An are likely to prove the more effective.
Fig. 2 shows the relationship between liquid depth d and preferred ranges of the ratio Am/An. It will be seen that an upper limit 30 of the ratio Am /An decreases from 12 to 5.5 as the predetermined depth d set by the weir 11 increases from 2 to 8 metres, while a lower limit 31 of 1.5 for the ratio Am/An is constant over the whole range of predetermined depths from 2 to 8 metres. The upper limit 30 does not exceed a value of 7.5 metres at a depth of 4 metres.
In a particular embodiment an upper limit 32 of the ratio Am/An falls from a value of 9.5 at 2 metres depth to a value of 4.5 at 8 metres depth, the limit 32 not exceeding 5.5 at a depth of 4 metres. In a further embodiment a lower limit 33 of the ratio Am/An falls from a value of 3.5 at a depth of 2 metres to a value of 2.5 at a depth of 8 metres, the lower limit 32 being not less than 3 at a depth of 4 metres.
In yet another embodiment an upper limit 34 of the ratio Am/An falls from a value of 7.5 at a depth of 2 metres to 4 at a depth of 8 metres, the limit 34 not exceeding a value of 5 at a depth of 4 metres.
In a still further embodiment a lower limit 35 of the ratio Am/An falls from a value of 5 at a depth of 2 metres to a value of 3 at 8 metres, the limit 35 being not less than 3.8 at a depth of 4 metres.
While the ranges of values of the depth d and the ratio Am/An between the upper and lower limits 30, 31 in Fig. 2 have been found to give oxygenation efficiencies of between 3.5 and 4 kilograms of oxygen per kilowatt hour, the values between the limits 32, 33 provide a more restricted range which will cater for tolerances in the structure and Dperation of the apparatus. The values between the limits 34, 35 provide a still more restricted, and preferred, range of operating conditions.
In general the more restricted ranges of operating conditions have been found to provide higher oxygenation efficiencies than the wider ranges. The efficiencies obtainable between the wider limits 30, 31 are nevertheless higher than those previously thought to be obtainable over the range of liquid depths disclosed herein.
The injector pump 17 is located at or adjacent the surface of the liquid in the tank, and the manifold 16 is also located as close as reasonably possible to the liquid surface, to reduce the work required of the pump 13.
Subject to the foregoing relationships between Am, An and d, it has been found that satisfactory oxygenation efficiencies are obtainable when the delivery head of the pump 12, relative to the liquid surface, is maintained at between 10% and 100% of the depth of the bottom of the mixing pipe 20 below the surface of the liquid in the tank. Additionally, oxygenation efficiency is improved if the cross-sectional area Ao of the injector pump outlet is between 1.05 and 2.5 times the area An.
In an alternative embodiment the circulating pump 12 may be dipensed with and the liquid be supplied to the nozzle 18 under pressure derived from some other source, as for example the elevation head of a separate reservoir. In this latter case the head of the liquid supplied to the nozzle 18 is also maintained at between 10% and 100% of the depth of the bottom of the pipe 20 below the surface of the liquid in the tank.
In other embodiments the nozzle 18, pipe 20 and diffuser 21 are not of circular section, and in particular may have elongate cross section.

Claims (11)

1. An apparatus for combining a liquid and a gas, comprising a tank for containing the liquid, means for maintaining a substantially constant predetermined depth of liquid in said tank, an injector pump having a nozzle for discharging liquid, an inlet through which gas can be drawn as a result of passage of liquid through said nozzle, and an outlet, means for supplying a liquid under pressure to said injector pump nozzle, a mixing pipe communicating with said injector pump outlet and extending therefrom to a position adjacent the bottom of said tank, and a deflector for urging a gas-liquid stream leaving said mixing pipe in a direction transverse to the axis thereof, the cross-sectional area (Am) of said mixing pipe and the cross-sectional area (An) of said nozzle 1.5 and 12, the upper limit of this ratio decreasing with increase in said predetermined depth between 2 and 8 metres.
2. An apparatus as claimed in claim 1 in which the values of said upper limit do not exceed 7.5 for a depth of 4 metres and do not exceed 5.5 for a depth of 8 metres.
3. An apparatus as claimed in claim 1 or claim 2 in which said ratio is not less than 1.5 over a range of depths between 2 and 8 metres.
4. An apparatus as claimed in claim 3 in which the values of said upper limit do not exceed 9.5, 5.5 and 4.5 for respective predetermined depths of 2, 4 and 8 metres.
5. An apparatus as claimed in claim 4 in which the values of said upper limit do not exceed 7.5, 5 and 4 for respective predetermined depths of 2, 4 and 8 metres.
6. An apparatus as claimed in any of claims 3 to 5 in which the values of said ratio are not less than 3.5, 3 and 2.5 for respective predetermined depths of 2, 4 and 8 metres.
7. An apparatus as claimed in claim 6 in which the values of said ratio are not less than 5, 3.8 and 3 for respective predetermined depths of 2, 4 and 8 metres.
8. An apparatus as claimed in any preced ing claim in which the cross-sectional area of said injector pump outlet is between 1.05 and 2.5 times the cross-sectional area of said injector pump nozzle.
9. An apparatus as claimed in any preceding claim in which said supply means comprises a pump for drawing said liquid from said tank.
10. A method of operating an apparatus as claimed in claim 9, said method including maintaining the delivery head of said pump, relative to a liquid surface in said tank, at between 10% and 100% of the depth of the bottom of said mixing pipe below said liquid surface.
11. An apparatus for combining a liquid and a gas substantially as hereinbefore described with reference to the accompanying drawings.
GB8030484A 1979-10-03 1980-09-22 Apparatus for combining a liquid and a gas Expired GB2059790B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8030484A GB2059790B (en) 1979-10-03 1980-09-22 Apparatus for combining a liquid and a gas

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB7934243 1979-10-03
GB8030484A GB2059790B (en) 1979-10-03 1980-09-22 Apparatus for combining a liquid and a gas

Publications (2)

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GB2059790A true GB2059790A (en) 1981-04-29
GB2059790B GB2059790B (en) 1983-03-02

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2118449A (en) * 1981-11-06 1983-11-02 Boc Group Plc Dissolving gas in a liquid
US4624626A (en) * 1985-03-08 1986-11-25 Sherfinski & Raasch Water Systems, Inc. Venturi odor dissipator
US5350543A (en) * 1992-05-14 1994-09-27 Spradley William E Method and apparatus for aerating an aqueous solution
EP1369386A3 (en) * 2002-05-31 2005-01-26 RHEBAU Rheinische Beton- und Bauindustrie GmbH & Co. Device for aeration of waste water and for cleaning a membrane assembly and small-scale waste water treatment plant containing this device
WO2010092569A1 (en) 2009-02-10 2010-08-19 Diffusair Ltd. Device and method for dissolving gas into a liquid
EP2225013A1 (en) * 2007-12-07 2010-09-08 Blue Planet Environmental Inc. Device to infuse gas into liquid
CN103316603A (en) * 2013-07-05 2013-09-25 江洪 Gas-liquid mixer
FR3106072A1 (en) * 2020-01-13 2021-07-16 Olivier Yves Christian Demay Mechanical oxygenation system by supersaturation for lakes, lagoons and rivers

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2118449A (en) * 1981-11-06 1983-11-02 Boc Group Plc Dissolving gas in a liquid
US4624626A (en) * 1985-03-08 1986-11-25 Sherfinski & Raasch Water Systems, Inc. Venturi odor dissipator
US5350543A (en) * 1992-05-14 1994-09-27 Spradley William E Method and apparatus for aerating an aqueous solution
EP1369386A3 (en) * 2002-05-31 2005-01-26 RHEBAU Rheinische Beton- und Bauindustrie GmbH & Co. Device for aeration of waste water and for cleaning a membrane assembly and small-scale waste water treatment plant containing this device
EP2225013A1 (en) * 2007-12-07 2010-09-08 Blue Planet Environmental Inc. Device to infuse gas into liquid
EP2225013A4 (en) * 2007-12-07 2014-09-03 Blue Planet Environmental Inc Device to infuse gas into liquid
WO2010092569A1 (en) 2009-02-10 2010-08-19 Diffusair Ltd. Device and method for dissolving gas into a liquid
CN103316603A (en) * 2013-07-05 2013-09-25 江洪 Gas-liquid mixer
FR3106072A1 (en) * 2020-01-13 2021-07-16 Olivier Yves Christian Demay Mechanical oxygenation system by supersaturation for lakes, lagoons and rivers

Also Published As

Publication number Publication date
GB2059790B (en) 1983-03-02

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PCNP Patent ceased through non-payment of renewal fee