Classifications

• • 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
  • B01F23/231—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids by bubbling
  • B01F23/23105—Arrangement or manipulation of the gas bubbling devices
  • B01F23/2312—Diffusers
  • B01F23/23124—Diffusers consisting of flexible porous or perforated material, e.g. fabric
  • B01F23/231245—Fabric in the form of woven, knitted, braided, non-woven or flocculated fibers or filaments
• • 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
  • C02F3/20—Activated sludge processes using diffusers
  • C02F3/208—Membrane aeration
• • 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
  • B01F23/231—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids by bubbling
  • B01F23/23105—Arrangement or manipulation of the gas bubbling devices
  • B01F23/2312—Diffusers
  • B01F23/23123—Diffusers consisting of rigid porous or perforated material
• • 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
  • B01F23/231—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids by bubbling
  • B01F23/23105—Arrangement or manipulation of the gas bubbling devices
  • B01F23/2312—Diffusers
  • B01F23/23124—Diffusers consisting of flexible porous or perforated material, e.g. fabric
• • 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
  • B01F23/231—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids by bubbling
  • B01F23/23105—Arrangement or manipulation of the gas bubbling devices
  • B01F23/2312—Diffusers
  • B01F23/23124—Diffusers consisting of flexible porous or perforated material, e.g. fabric
  • B01F23/231244—Dissolving, hollow fiber membranes
• • 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
  • B01F23/237—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids characterised by the physical or chemical properties of gases or vapours introduced in the liquid media
  • B01F23/2373—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids characterised by the physical or chemical properties of gases or vapours introduced in the liquid media for obtaining fine bubbles, i.e. bubbles with a size below 100 µm
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F2215/00—Auxiliary or complementary information in relation with mixing
  • B01F2215/04—Technical information in relation with mixing
  • B01F2215/0413—Numerical information
  • B01F2215/0418—Geometrical information
  • B01F2215/0431—Numerical size values, e.g. diameter of a hole or conduit, area, volume, length, width, or ratios thereof
• • 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

Definitions

• Semmens (column 5, lines 27 to 48) teaches the use of a thin, smooth, chemically resistant, non-porous, gas permeable polymer coating on the exterior surface of a major portion of each fiber to inhibit the accumulation of debris and microorganism which tend to clog the surface through which the gas diffuses under high pressures of 20 to 60 psi on the interior of the fibers, while achieving higher gas transfer rats and preventing the loss of gas m bubbles. Semmens further states that if the fibers are uncoated, the pressure differential, that is, the pressure of the gas in excess of that of the liquid, has to be below 2 psi. To avoid bubbles.
• Semmens (column 4, lines 39 to 42) states that generally speaking a gas pressure of at least 45 psi above the water will be used Clearly , a: low gas pressures where no bubbles were formed, the transfer was not considered adequate, and sufficient gas pressure was thought necessary to transfer trapped liquid out of the file membrane (see column 4, lines 34 to 36) . While the device of Semmens is useful, the gas permeable polymer coating necessitates the use of elevated gas pressures, while the relatively low liquid pressures will ultimately limit the achievable dissolved gas concentration. It has also been proposed m United States Patent No. 4,950,431, dated August 21, 1990, A.J.
• Rudick et al to provide an apparatus, for making and dispensing carbonated water, m which C0 2 , pressurized to 31 psi, from hollow semi -permeable membrane fibers is mixed with chilled municipal water m a carbonator housing.
• the CO is provided by an input line having a spring biased spool valve which mamtams the interior of the carbonator housing pressurized to the level of the CO, i.e., 31 psi, and provides the driving force for dispensing the carbonated water (column 4, lines 2 to 8) . Further, when the incoming water pressure is greater than 31 psi to the carPonator housing, tne caroonator functions as a simple m-line continuous carbonator during a dispenser operation.
• Rudick et al is concerned with producing and dispensing carbonated water which will effervesce at atmospheric pressure.
• CO may be aborbed directly into the water without formation of bubbles, it is necessary for the absorbed portions of CO, to be of sufficient size to readily coalesce and effervesce, m the manner of a carbonated beverage, when vented to atmospheric pressure by being dispensed by the Rudick et al apparatus. For this to occur, the carbonated water has to be delivered to the drinking cup m a turbulent state.
• a gas/liquid mixing apparatus comprising: a) a casing having a gas inlet, a liquid inlet, and a gas/liquid mixture outlet, b) a microporous membrane m the casing, the membrane having, i) effective, gas/liquid contacting, pore pathway diameters generally m the
• a gas outlet is provided from the casing
• the microporous membrane is one of a plurality of similar, microporous, hollow fibers bundled together m the casing
• a first block of epoxy resin is at one end of the bundle, and seals that end of the bundle, with open ends of the fibers at that end of the bundle communicating with the gas inlet
• a second blocK of epoxy resin is at the other end of the bundle, and seals that end of the bundle with open ends of the fibers at that end of the bundle communicating with the gas outlet
• the gas inlet and gas/liquid mixture outlet are on opposite sides of the casing for liquid to flow across substantially the whole outer surface of tne fibers.
• the bundle of fibers may comprise the warp of a woven, open mesh structure, and solid, water repellent fibers are provided forming the weft, and the open mesh structure is coiled to form the bundle.
• the apparatus may further comprise a tank, and a pump connected to deliver liquid to the liquid inlet, and the low liquid turbulence incurring, gas/liquid mixture conveying and delivering device, is connected to the tank to gently deliver gas/liquid mixture thereto.
• the membrane has a porosity of at least
• a method of mixing gas with a liquid comprising: a) bringing a liquid into contact m a casing with a mixing liquid repellent side of a microporous membrane naving effective, gas/liquid contacting pore patnway diameters generally in the range
• the microporous membrane may be one of a plurality of similar microporous, hollow fibers, and the gas is passed down the hollow fibers, while the liquid is passed over the liquid repellant outer side of the hollow fibers.
• Gas/liquid mixture m the receiving vessel may be frozen to increase the retention time of the discrete, microscopic portions of the gas m the liquid.
• gas pressure is at least 0.07 k/o cm less than that of the liquid.
• the present invention provides a novel gas/liquid mixture which, when compared to known gas/liquid mixtures, has a) a surprisingly greater mass of gas m a given volume of liquid, to the point of supersaturation, and b) exhibits a vastly increased period during which gas remains dispersed in the liquid in discrete portions .
• This long dwell time of supersaturated gas m the liquid, m discrete portions is particularly useful m processes which use oxygen consuming microorganisms m water, or chemical reactions accelerated by oxygen, because the excess oxygen provided by supersaturation tends to replace the consumed oxygen before being lost to atmosphere .
• the present invention is described m the following embodiment with the gas and liquid slightly above atmospheric pressure.
• the gas and liquid it is within the scope of the present invention for the gas and liquid to be at atmospheric pressure, or even under a vacuum, provided the relationship between the gas and liquid pressures is adhered to, and the gas/liquid mixture is handled gently, that is, not subjected to a turbulence producing pressure changes.
• low-liquid turbulence- incurring, gas/liquid mixture conveying and delivering means that the gas/liquid mixture is handled gently so that at least a ma or portion of the discrete, microscopic portions of gas remain discrete, for example, the gas/liquid mixture, I) is transported fairly smoothly,
• Figure 1 is a flow diagram of an apparatus used to verify the present invention
• FIG 2 is a diagrammatic, sectional side view of the gas/liquid contacting device used m the apparatus shown m Figure 1,
• Figure 3 is an end view of the portion of a bundle of hollow, microporous fibers shown m Figure 2, before being coiled into the bundle,
• Figure 4 shows graphs depicting the oxygen transfer data obtained by tests using the apparatus shown m Figures 1 to 3,
• Figure 5 shows graphs depicting the oxygen content m water plotted against time
• Figures 6 and 7 show graphs depicting tne extraction of copper from a slurry of mined copper using water saturated m oxygen from the tests whose results are depicted m graphs of Figure 4.
• FIG. 1 there is shown a gas/liquid mixing apparatus, comprising: a) a casing 2 having a gas inlet 4, a liquid inlet 6 and a gas/liquid mixture outlet 8, b) a microporous membrane 10 m the casing 2, the membrane having, l) effective, gas/liquid contacting, pore pathway diameters generally, m the range
• a side 12 that is repellent to the liquid to be mixed the membrane 10 dividing the casing interior 14 into a liquid path, on the water repellent side 12, between the liquid inlet 6 and thegas/liquid mixture outlet 8, and a gas chamber from the gas inlet 4,
• fluid pressure regulating means connected to the casing 2, comprising a liquid back pressure regulator and gauge 18, and a gas pressure regulator and gauge 20, for regulating the gas/liquid pressure relationship m the casing 2 so that, i) the gas pressure does not exceed the liquid pressure
• pressurized liquid does not pass through the membrane micropores, and d) a low-liquid-turbulence incurring gas/liquid mixture conveying and delivery device, m the form of a pipe 29, having a rounded corner and connected to the gas/liquid mixture outlet 8 and terminating below a liquid level 23 of a tank 24 to gently deliver gas/liquid mixture thereto.
• the apparatus may also include gas outlets 5 for removing any liquid that may collect in the gas chamber 2.
• the gas outlet 5 is also useful for connecting two or more casings 2 m series flow.
• the apparatus shown m Figure 1 was used m tests to verify the present invention and included a gas valve 21, a high pressure oxygen cylinder 22, the open-topped, gas/liquid mixture tank 24, forming a receiving vessel for gas/liquid mixture, a variable speed liquid pump 26, a liquid pressure regulator and gauge 28, and a dissolved oxygen analyzer 30.
• the pipe 29 was transparent to enable observation of the condition of the gas/liquid mixture therein.
• Gas flow meters 52 and 54 were provided together with a gas valve 56.
• the liquid feed was supplied from tank 58 and accurately controlled by return line 60 and valve 62.
• similar parts to those shown m Figure 1 are designated by the same reference numerals and the previous description is relied upon to desc ⁇ oe them.
• tne microporous membrane 10 comprises one of a bundle of hollow, microporous fibers 27, each with a liquid repellent outer side 12 and sealed m epoxy resin discs 31 and 32, which, m turn, are sealed m the casing 2 by ⁇ O'- rings 34 and 36 respectively.
• the assembly comprising the bundle of microporous fibers 27 and discs 31 and 32, are supported by a central support tune 38 which is sealed m the casing and spaces tne discs 31 and 32 to provide plenum chambers 40 and 41.
• Plenum chamber 40 receives gas from inlet 4, while plenum chamber 41 passes gas to outlet 5 to the flow meter 54 ( Figure 1) .
• the upper ends of the microporous fibers have exposed, open ends above the disc 31, to the plenum chamber 40.
• the lower ends of the microporous fibers have exposed, open ends below the disc 32 to the plenum chamber 41.
• the central support tube 38 provides the liquid inlet 6 and has liquid outlet ports 42 to the portion of the interior of the casing 2 between the discs 31 and 32.
• the gas/liquid mixture outlet 8 is one of two, similar outlets, the other one being designated by reference numeral 9. Both of the outlets 8 and 9 are connected to the pipe 29 ( Figure 1) . In other embodiments, either outlet 8 or 9 is used to recirculate gas/liquid mixture for further gas enrichment.
• Figure 3 shows a portion 44 of the hollow, microporous fibers 27 (Figure 21) before they are coiled into the bundle.
• the microporous fibers 27 from the warp of a woven, open mesh structure, with solid fibers 46, of a similar liquid repellent substance to the microporous fibers, forming the weft.
• the hollow, microporous fibers 27 ( Figures 2 and 3) each had an outside diameter of about that of a fishing line and were made from polyethylene or polypropylene, both of which are water repellent .
• the size range of the micropores was controlled m the microporous fiber manufacturing process to produce predetermined, effective pathway diameters, through the walls of the nollow, microporous fibers
• the gas into liquid breakthrough pressure of tne microporous membranes was of the order of 40 p.s.i. (2.8 K per cm 2 ) .
• the specific surface area of the bundle of hollow, microporous fibers was about 3,000 square meters per cubic metre of volume. More specifically, tne following
• Table I gives details of two different, polyethylene fibers used m the tests .
• ⁇ p is the average pore size m microns
• Do is the outside diameter of the fibers m microns
• Di is the inside diameter of the fibers m microns.
• L is the length of the fibers m cms
• No is the number of fibers m
• Dc is the inside diameter of the bundle
• Ds is the outside diameter of the pundle.
• the pump 26 was supplied with city water via the tank 58 which was a 45 gallon holding tank. Pressurized water was fed from the pump 26 to the inlet 6. Simultaneously, pressurized oxygen was supplied to the inlet 4 with care taken to assure that the oxygen pressure m the casing 2 never exceeded the water pressure.
• the interfacial area created by the micropores allowed a controlled transfer of oxygen to the water, the driving force for this transfer being the difference in equilibrium oxygen saturation levels between water at atmospheric pressure versus water at elevated pressures. (For example: approximately each atmosphere of oxygen partial pressure that water is exposed to raises its equilibrium oxygen saturation level by 40 ppm. )
• the final module manufacturing step was the 'opening of the fibres' . This was accomplished, normally, by a high speed, carbide tipped, rotary saw blade. An 'open fibre' test was then performed on each module to determine the 'goodness' of the cut. This was done by measuring the pressure drop of water flowing down the fibre bores . The term 'open fibre' is actually a misnomer m that the actual pressure drop was compared to the theoretical pressure drop. For example, modules Type 1 & 3 used previously, routinely gave an open fibre result of >95% (when the blade was sharp) .
• the thick, horizontal line represents saturation level of oxygen m the water.
• supersaturated liquid produced according to the present invention has unique properties that can be used where for example, oxygenation of a liquid is required without the use of pressurized cylinders and powered oxygenation equipment, for example, m the transportation of live fish or seafood.
• ⁇ shows the results of the known acid leaching process where oxidation enhancing ferric sulphate is added to the slurry while air is bubbled through it, and ⁇ shows the results of circulating the supersaturated
• test results gave some indication of the significant advantages of the present invention over known oxygen/water mixing processes .
• a large part of the operating cost of any oxygenation process is the power consumption required to transfer the oxygen to the water, and this is also an excellent performance indicator.
• Power consumption is normally expressed m terms of standard aeration efficiency (SAE) , and the units it is expressed m are pounds of oxygen used per hour per applied horsepower, and this is used in the following comparison using a Type III module with liquid flows of 5 to 6 litres per minute and pressure less than 20 p.s.i.
• SAE standard aeration efficiency
• the hollow, microporous fibers comprise the weft of an open mesh structure .
• the liquid inlet 6 ( Figure 2) has a rounded corner 48 leading to the interior of the casing 2
• the gas/liquid mixture outlet 8 has a rounded corner 50 leading from the interior of the casing 2.
• gases which may be used m the present invention are, for example S0 2 , 0,, N : , CHvisor , C0 2 , C 2 H 6 , C 2 H, , C 3 H 8 , F 2 and CI.
• liquids which may be used m the present invention are, for example, any acids, bases or hydrocarbons to which the membrane material is repellent.
• Compatibility includes a degree of solubility of the gas m the liquid, and the liquid is repellant to the membrane material .

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Textile Engineering (AREA)
• Nanotechnology (AREA)
• Biodiversity & Conservation Biology (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Organic Chemistry (AREA)
• Hydrology & Water Resources (AREA)
• Microbiology (AREA)
• Separation Using Semi-Permeable Membranes (AREA)

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• 1999
  • 1999-05-05 CA CA002271170A patent/CA2271170C/en not_active Expired - Fee Related
• 2000
  • 2000-05-03 DE DE2000621549 patent/DE60021549T2/de not_active Expired - Lifetime
  • 2000-05-03 ES ES00925006T patent/ES2246848T3/es not_active Expired - Lifetime
  • 2000-05-03 AU AU43887/00A patent/AU778289B2/en not_active Ceased
  • 2000-05-03 AT AT00925006T patent/ATE300351T1/de not_active IP Right Cessation
  • 2000-05-03 EP EP00925006A patent/EP1173271B1/en not_active Expired - Lifetime
  • 2000-05-03 WO PCT/CA2000/000514 patent/WO2000067886A1/en not_active Ceased
  • 2000-05-03 JP JP2000616905A patent/JP2002543960A/ja active Pending

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