EP0234768A2 - Agitator - Google Patents

Agitator Download PDF

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Publication number
EP0234768A2
EP0234768A2 EP87300911A EP87300911A EP0234768A2 EP 0234768 A2 EP0234768 A2 EP 0234768A2 EP 87300911 A EP87300911 A EP 87300911A EP 87300911 A EP87300911 A EP 87300911A EP 0234768 A2 EP0234768 A2 EP 0234768A2
Authority
EP
European Patent Office
Prior art keywords
blades
rotor
assembly according
sparging
fluid
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
EP87300911A
Other languages
German (de)
French (fr)
Other versions
EP0234768B1 (en
EP0234768A3 (en
Inventor
John Colin Middleton
Colin Ramshaw
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.)
Imperial Chemical Industries Ltd
Original Assignee
Imperial Chemical Industries Ltd
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Filing date
Publication date
Application filed by Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
Priority to AT87300911T priority Critical patent/ATE83169T1/en
Publication of EP0234768A2 publication Critical patent/EP0234768A2/en
Publication of EP0234768A3 publication Critical patent/EP0234768A3/en
Application granted granted Critical
Publication of EP0234768B1 publication Critical patent/EP0234768B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • B01F23/233—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements
    • B01F23/2331—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements
    • 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
    • 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
    • B01F23/2331—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements
    • B01F23/23311—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements through a hollow stirrer axis
    • 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
    • B01F23/2331—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements
    • B01F23/23314—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements through a hollow stirrer element
    • 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
    • B01F23/2336—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the location of the place of introduction of the gas relative to the stirrer
    • B01F23/23362—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the location of the place of introduction of the gas relative to the stirrer the gas being introduced under the stirrer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/05—Stirrers
    • B01F27/11—Stirrers characterised by the configuration of the stirrers
    • B01F27/112—Stirrers characterised by the configuration of the stirrers with arms, paddles, vanes or blades
    • B01F27/1123—Stirrers characterised by the configuration of the stirrers with arms, paddles, vanes or blades sickle-shaped, i.e. curved in at least one direction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/05—Stirrers
    • B01F27/11—Stirrers characterised by the configuration of the stirrers
    • B01F27/112—Stirrers characterised by the configuration of the stirrers with arms, paddles, vanes or blades
    • B01F27/1125—Stirrers characterised by the configuration of the stirrers with arms, paddles, vanes or blades with vanes or blades extending parallel or oblique to the stirrer axis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/05—Stirrers
    • B01F27/11—Stirrers characterised by the configuration of the stirrers
    • B01F27/115—Stirrers characterised by the configuration of the stirrers comprising discs or disc-like elements essentially perpendicular to the stirrer shaft axis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/05—Stirrers
    • B01F27/11—Stirrers characterised by the configuration of the stirrers
    • B01F27/19—Stirrers with two or more mixing elements mounted in sequence on the same axis
    • B01F27/192—Stirrers with two or more mixing elements mounted in sequence on the same axis with dissimilar elements

Definitions

  • This invention relates to agitators for the dispersion of a fluid in a liquid.
  • Disc turbine agitators with a plurality of axially aligned plane paddle blades are known for the dispersion of sparged gases as small bubbles in liquids in tanks and the concomitant mixing of the tank contents.
  • a vortex low pressure zone forms behind each rotating blade of the turbine, and with the gas flow rates frequently encountered in industry, the gas tends to collect and be held as a cavity in this zone; this disadvantageously reduces dispersion and mixing efficiency and can cause turbine blade erosion.
  • the same problem would be found with a sparged liquid less dense than the tank liquid.
  • the present invention provides a turbine agitator assembly comprising a reservoir for liquid, a rotor mounted in the reservoir and with a plurality of radially extending blades, and means for sparging a fluid into liquid in the reservoir, the fluid sparging means and the rotor being so constructed and arranged that, in use, the rotor blades (submerged in the liquid) and/or the liquid flow they generate disperse the sparged fluid, characterised in that each of the blades is hollow and has a discontinuous leading edge, only a single trailing edge along an acute angle, no external concave surface and an open radially outer end.
  • the blade may have a symmetrical cross-section, having a circular, parabolic or elliptical section leading face merging smoothly into a sphenoidal (i.e. wedge shaped) or sharply elongate parabolic or elliptical section trailing part.
  • a sphenoidal i.e. wedge shaped
  • sharply elongate parabolic or elliptical section trailing part i.e. wedge shaped
  • the term 'trailing edge along an acute angle' thus includes both angular and sharply radiused edges.
  • Parabolic or elliptical section leading faces are favoured as improving the streamline around the blade, although the leading part may also be sphenoidal.
  • a preferred blade shape is a symmetrical aerofoil-like cross-section.
  • the blade is hollow and the leading edge is discontinuous, for example in the form of holes, or in the preferred form of a slot symmetrically disposed in the leading face of a symmetrical cross-section blade.
  • the radially outer end of the blade is at least partially open, so that such a blade provides a scooping action which disperses and mixes by pumping the scooped liquid radially outwards.
  • the blade will be made of conventional metals or plastics used for turbine agitator paddles.
  • the blade In its general form the blade has two elongate axes, one radial and one transverse, defining a 'blade plane'.
  • This blade plane will generally coincide with or lie parallel to any plane of rotation described by the blade in use, that is the blade is usually not set at an 'attack angle' on or with respect to the rotor shaft.
  • this latter possibility is not excluded, but the skilled man will readily appreciate that the angle should not be so great that the trailing (or any leading) edge behaves effectively as an axially projecting edge, and/or any trailing part of the blade surface behaves effectively as a concave surface, in tending to produce substantial vortices.
  • the blades of the turbine rotor may be arranged in the same rotational plane or in any number of parallel rotational planes. It is preferred that the blades are arranged regularly within any one plane so that rotational balance is maximised. Preferably they are also (as apt) so arranged along the shaft and with respect to each blade in any other plane in accordance with routine engineering practice that torsional balance is maximised, for example, they are arranged with equal numbers of blades in each plane, and with corresponding blades in different planes axially in register or with all the planes regularly rotationally skewed with respect to one another.
  • the blades may also be set at any angle to the rotor shaft in an axial direction, other than a right angle in order to provide an axial component of the discharge flow.
  • the rotor may have 2 or more blades.
  • the mixing efficiency of the turbine will generally increase with the number of blades in any one plane until such point that the blades are so close with respect to their transverse dimension that in use the action of any one blade interferes with the action of the following blade.
  • the useful number of planes of blades is limited by any mutual interference between the planes due to proximity.
  • the addition of further planes of blades increasingly remote from a single axial sparging source may also not increase the fluide dispersing efficiency of the turbine, but may still assist mixing of the liquid and/or liquid-fluid dispersion in the reservoir.
  • suitable blade numbers include 2 to 24 coplanar blades, typically 4 to l2, and up to 5 planes of blades, typically l.
  • dimensions of the rotor are determined by the size of the reservoir, and usually the diameter will be one third to a half the corresponding reservoir transverse dimension.
  • the fluid sparging means may have a single aperture, or multiple apertures such as a row, grid, rose or ring. Although the sparging of liquids, in particular those less dense than the reservoir liquids, is not excluded, the sparged fluid will often be a gas.
  • the rotor and fluid sparging means may be placed in any orientation and mutual position which ensures that the fluid is delivered either to the volume swept by the rotor blades or to any directly adjacent zone on which any liquid flow generated by the rotor blades impinges (in both cases 'the dispersion zone').
  • the rotor may be mounted in any orientation, although it will often be convenient to mount it upright with the sparging means mounted on the reservoir above or below it, e.g. spaced axially from it, so that the fluid may be delivered to the dispersion zone through the liquid essentially under gravity, either from below for a gas or liquid less dense than the reservoir liquid or from above for a denser liquid.
  • the sparging means may then suitably be a hole, rose or ring coaxial with the rotor.
  • the blades will not generally extend from the rotor shaft itself but will each be mounted on an arm or an equivalent structure on the shaft. It will be apparent that an axial hole, rose or ring sparging means small diameter than the overall rotor diameter which does not overlap the blades will not deliver fluid to the dispersion zone without a deflector. In such a case the blades may conveniently be mounted extending from the periphery of a rotor disc, the disc acting as a deflector. With the typical blade dimentions given hereinbefore, the disc will typically be 3D/4 in diameter, where D is the overall rotor diameter.
  • the fluid may of course be delivered to a zone radially outside the volume swept by the blades, since the liquid pumped into this zone by the blades makes it a dispersion zone; a sparging ring may be used.
  • the rotor may be mounted cross­wise with the sparging means mounted on the reservoir and spaced radially from it above or below, again conveniently to allow delivery essentially under gravity.
  • the sparging means may then suitably be an axially aligned row, a transverse straight or arcuate row or a planar or curved grid depending on the rotor structure.
  • the sparging means may be mounted on the rotor, for example as an aperture or apertures in front of each blade or spaced axially from the or a blade plane.
  • the present assembly is particularly useful for gas-liquid mass transfer processes, and for low-shear thorough mixing, e.g. of sensitive substrates such as living cell fermentation suspensions or polymer latices or dispersions subject to ready degradation or coagulation.
  • a rotor 4 is rotatably mounted vertically within a reservoir 2 (not shown) capable of holding a liquid 3 (also not shown) to submerge the rotor 4.
  • the rotor 4 consists of a shaft 5 (driven by an electric motor 6 - not shown) on which a plurality (four or six) radially extending blades 7 are mounted regularly about the shaft 5 in a single plane by means of a disc or arms 8.
  • Each blade 7 is of symmetrical uniform aerofoil cross-section with a single sphenoidal acute-angle trailing edge 9 extending the length of the blade 7.
  • Each blade 7 is hollow and its leading face l0 has a symmetically disposed slot ll extending the length of the blade 7.
  • the ends l2 of the blade 7 are open.
  • the blades 7 are mounted such that their central planes of symmetry are coplanar.
  • a means for sparging gas l4 is, in Figures l to 3, mounted on the reservoir below the level of and coaxial with the rotor.
  • it is a single aperture or a sparging ring of apertures which do not overlap the blades 7.
  • it is a sparging ring lying below a zone l9 radially outside the volume l8 swept by the blades in use.
  • the sparging means l4 consists of four apertured tubes mounted on, projecting from, and communicating with the hollow interior of the shaft 5, and regularly spread between and coplanar with the blades 6. Their apertures l5 are in the trailing face l6 of each tube l4.
  • the reservoir 2 is filled with liquid 3 to submerge the blades 7 of the rotor 4, which is then rotated in the direction of arrow A.
  • Gas l7 is then supplied via sparging apertures l5 (in Figure 4 through the hollow interior of the rotor shaft 5 and rods l3) to the volume l8 swept by the blades (in Figure l by deflection by the disc 8) or the zone l9.
  • liquid 3 is scooped in by the blades 7 through the slot ll and discharged through the open blade end l2 into the dispersion zone l9.
  • the gas l7 flows over the outer surface of the blades 7, and in all cases the gas is dispersed in the zone l9.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Accessories For Mixers (AREA)
  • Liquid Crystal Substances (AREA)
  • Mixers With Rotating Receptacles And Mixers With Vibration Mechanisms (AREA)

Abstract

A turbine agitator assembly comprising a reservoir for liquid, a rotor mounted in the reservoir and with a plurality of radially extending blades (7), and means (14) for sparging a fluid into liquid in the reservoir, the fluid sparging means and the rotor being so constructed and arranged that, in use, the rotor blades (submerged in the liquid) and/or the liquid flow they generate disperse the sparged fluid, characterised in that each of the blades is hollow and has a discontinuous leading edge (10), only a single trailing edge (9) along an acute angle, no external conclave surface and an open radially outer end.

Description

  • This invention relates to agitators for the dispersion of a fluid in a liquid.
  • Disc turbine agitators with a plurality of axially aligned plane paddle blades are known for the dispersion of sparged gases as small bubbles in liquids in tanks and the concomitant mixing of the tank contents. In use, a vortex low pressure zone forms behind each rotating blade of the turbine, and with the gas flow rates frequently encountered in industry, the gas tends to collect and be held as a cavity in this zone; this disadvantageously reduces dispersion and mixing efficiency and can cause turbine blade erosion. The same problem would be found with a sparged liquid less dense than the tank liquid. We have now designed a turbine agitator in which vortex formation and its deleterious consequences are minimised, and which provides efficient dispersion and mixing.
  • Accordingly, the present invention provides a turbine agitator assembly comprising
    a reservoir for liquid,
    a rotor mounted in the reservoir and with a plurality of radially extending blades, and
    means for sparging a fluid into liquid in the reservoir,
    the fluid sparging means and the rotor being so constructed and arranged that, in use, the rotor blades (submerged in the liquid) and/or the liquid flow they generate disperse the sparged fluid,
    characterised in that each of the blades is hollow and has a discontinuous leading edge, only a single trailing edge along an acute angle, no external concave surface and an open radially outer end.
  • In conventional disc turbine agitators, we have found that vortices are generated where fluid flow is not streamline along the blade surface, but becomes 'separated', for example at projecting edges (e.g. the axial edges of conventional axially-aligned paddle blades), where a trailing external surface is concave, or where there is no acute trailing edge, e.g. with circular, elliptical, square or oblong cross-section blades.
  • We believe that any blade fulfilling the foregoing criteria for a blade of this invention will be suitable. Within this, the blade may have a symmetrical cross-section, having a circular, parabolic or elliptical section leading face merging smoothly into a sphenoidal (i.e. wedge shaped) or sharply elongate parabolic or elliptical section trailing part. It will be seen that the term 'trailing edge along an acute angle' thus includes both angular and sharply radiused edges. Parabolic or elliptical section leading faces are favoured as improving the streamline around the blade, although the leading part may also be sphenoidal. A preferred blade shape is a symmetrical aerofoil-like cross-section.
  • The blade is hollow and the leading edge is discontinuous, for example in the form of holes, or in the preferred form of a slot symmetrically disposed in the leading face of a symmetrical cross-section blade. The radially outer end of the blade is at least partially open, so that such a blade provides a scooping action which disperses and mixes by pumping the scooped liquid radially outwards.
  • Typical dimensions of a blade in the present assembly are:
    blade length = D/4, projected height = D/5, where D is the overall rotor diameter.
  • Typically the blade will be made of conventional metals or plastics used for turbine agitator paddles.
  • In its general form the blade has two elongate axes, one radial and one transverse, defining a 'blade plane'. This blade plane will generally coincide with or lie parallel to any plane of rotation described by the blade in use, that is the blade is usually not set at an 'attack angle' on or with respect to the rotor shaft. However, this latter possibility is not excluded, but the skilled man will readily appreciate that the angle should not be so great that the trailing (or any leading) edge behaves effectively as an axially projecting edge, and/or any trailing part of the blade surface behaves effectively as a concave surface, in tending to produce substantial vortices.
  • The blades of the turbine rotor may be arranged in the same rotational plane or in any number of parallel rotational planes. It is preferred that the blades are arranged regularly within any one plane so that rotational balance is maximised. Preferably they are also (as apt) so arranged along the shaft and with respect to each blade in any other plane in accordance with routine engineering practice that torsional balance is maximised, for example, they are arranged with equal numbers of blades in each plane, and with corresponding blades in different planes axially in register or with all the planes regularly rotationally skewed with respect to one another.
  • The blades may also be set at any angle to the rotor shaft in an axial direction, other than a right angle in order to provide an axial component of the discharge flow.
  • The rotor may have 2 or more blades. The mixing efficiency of the turbine will generally increase with the number of blades in any one plane until such point that the blades are so close with respect to their transverse dimension that in use the action of any one blade interferes with the action of the following blade. Similarly the useful number of planes of blades is limited by any mutual interference between the planes due to proximity. The addition of further planes of blades increasingly remote from a single axial sparging source may also not increase the fluide dispersing efficiency of the turbine, but may still assist mixing of the liquid and/or liquid-fluid dispersion in the reservoir.
  • Subject to the foregoing suitable blade numbers include 2 to 24 coplanar blades, typically 4 to l2, and up to 5 planes of blades, typically l.
  • Typically, dimensions of the rotor are determined by the size of the reservoir, and usually the diameter will be one third to a half the corresponding reservoir transverse dimension.
  • The fluid sparging means may have a single aperture, or multiple apertures such as a row, grid, rose or ring. Although the sparging of liquids, in particular those less dense than the reservoir liquids, is not excluded, the sparged fluid will often be a gas.
  • The rotor and fluid sparging means may be placed in any orientation and mutual position which ensures that the fluid is delivered either to the volume swept by the rotor blades or to any directly adjacent zone on which any liquid flow generated by the rotor blades impinges (in both cases 'the dispersion zone').
  • The rotor may be mounted in any orientation, although it will often be convenient to mount it upright with the sparging means mounted on the reservoir above or below it, e.g. spaced axially from it, so that the fluid may be delivered to the dispersion zone through the liquid essentially under gravity, either from below for a gas or liquid less dense than the reservoir liquid or from above for a denser liquid. The sparging means may then suitably be a hole, rose or ring coaxial with the rotor.
  • As is common with turbine agitators the blades will not generally extend from the rotor shaft itself but will each be mounted on an arm or an equivalent structure on the shaft. It will be apparent that an axial hole, rose or ring sparging means small diameter than the overall rotor diameter which does not overlap the blades will not deliver fluid to the dispersion zone without a deflector. In such a case the blades may conveniently be mounted extending from the periphery of a rotor disc, the disc acting as a deflector. With the typical blade dimentions given hereinbefore, the disc will typically be 3D/4 in diameter, where D is the overall rotor diameter.
  • The fluid may of course be delivered to a zone radially outside the volume swept by the blades, since the liquid pumped into this zone by the blades makes it a dispersion zone; a sparging ring may be used.
  • Alternatively, the rotor may be mounted cross­wise with the sparging means mounted on the reservoir and spaced radially from it above or below, again conveniently to allow delivery essentially under gravity. The sparging means may then suitably be an axially aligned row, a transverse straight or arcuate row or a planar or curved grid depending on the rotor structure.
  • In another aspect the sparging means may be mounted on the rotor, for example as an aperture or apertures in front of each blade or spaced axially from the or a blade plane.
  • Orientations of the rotor appropriate to or compatible with the disposition of the sparging means and blades will be self-evident to the skilled man.
  • Although useful in all applications where dispersion of two fluid phases is required, the present assembly is particularly useful for gas-liquid mass transfer processes, and for low-shear thorough mixing, e.g. of sensitive substrates such as living cell fermentation suspensions or polymer latices or dispersions subject to ready degradation or coagulation.
  • The present invention will now be described with reference to three specific embodiments of the rotor and sparging means, depicted in Figures l, 2, 3 and 4.
  • In the Figures, a rotor 4 is rotatably mounted vertically within a reservoir 2 (not shown) capable of holding a liquid 3 (also not shown) to submerge the rotor 4. The rotor 4 consists of a shaft 5 (driven by an electric motor 6 - not shown) on which a plurality (four or six) radially extending blades 7 are mounted regularly about the shaft 5 in a single plane by means of a disc or arms 8.
  • Each blade 7 is of symmetrical uniform aerofoil cross-section with a single sphenoidal acute-angle trailing edge 9 extending the length of the blade 7. Each blade 7 is hollow and its leading face l0 has a symmetically disposed slot ll extending the length of the blade 7. The ends l2 of the blade 7 are open. The blades 7 are mounted such that their central planes of symmetry are coplanar.
  • A means for sparging gas l4 is, in Figures l to 3, mounted on the reservoir below the level of and coaxial with the rotor. In Figures l and 2 it is a single aperture or a sparging ring of apertures which do not overlap the blades 7. In Figure 3 it is a sparging ring lying below a zone l9 radially outside the volume l8 swept by the blades in use. In Figure 4 the sparging means l4 consists of four apertured tubes mounted on, projecting from, and communicating with the hollow interior of the shaft 5, and regularly spread between and coplanar with the blades 6. Their apertures l5 are in the trailing face l6 of each tube l4.
  • In use, the reservoir 2 is filled with liquid 3 to submerge the blades 7 of the rotor 4, which is then rotated in the direction of arrow A. Gas l7 is then supplied via sparging apertures l5 (in Figure 4 through the hollow interior of the rotor shaft 5 and rods l3) to the volume l8 swept by the blades (in Figure l by deflection by the disc 8) or the zone l9. In all cases liquid 3 is scooped in by the blades 7 through the slot ll and discharged through the open blade end l2 into the dispersion zone l9. In Figures l, 2 and 4 the gas l7 flows over the outer surface of the blades 7, and in all cases the gas is dispersed in the zone l9.

Claims (10)

1. A turbine agitator assembly comprising a reservoir for liquid,
a rotor mounted in the reservoir and with a plurality of radially extending blades, and
means for sparging a fluid into liquid in the reservoir,
the fluid sparging means and the rotor being so constructed and arranged that, in use, the rotor blades (submerged in the liquid) and/or the liquid flow they generate disperse the sparged fluid,
characterised in that each of the blades is hollow and has a discontinuous edge, only a single trailing edge along an acute angle, no external concave surface and an open radially outer end.
2. An assembly according to claim l, wherein each blade has a symmetrical aerofoil-like cross-section with a parabolic or elliptical section leading face merging smoothly into a sphenoidal trailing part.
3. An assembly according to claim 2 having a slot symmetrically disposed in the leading face.
4. An assembly according to claim 2 wherein the blade plane coincides with or lies parallel to the plane of rotation of the blade in use.
5. An assembly according to claim l wherein the blades are arranged regularly in the same rotational plane or in each of a number of parallel rotational planes.
6. An assembly according to claim 5 the blades are arranged in a number of parallel rotational planes having the same number of blades in each plane and corresponding blades in different planes axially in register or with all the planes regularly rotationally skewed with respect to one another.
7. An assembly according to claim 5 having 4 to l2 blades in a single rotational plane.
8. An assembly according to claim l wherein the blades are mounted on a horizontal rotor disc and the assembly is so arranged that in use the disc serves to deflect the sparging fluid to the volume swept by the blades.
9. An assembly according to claim l wherein the sparging means is so arranged in use it delivers the sparging fluid to a zone radially outside the volume swept by the blades.
l0. An assembly according to claim l wherein the sparging means is mounted on the rotor.
EP87300911A 1986-02-17 1987-02-02 Agitator Expired - Lifetime EP0234768B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT87300911T ATE83169T1 (en) 1986-02-17 1987-02-02 STIRRER.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB868603904A GB8603904D0 (en) 1986-02-17 1986-02-17 Agitators
GB8603904 1986-02-17

Publications (3)

Publication Number Publication Date
EP0234768A2 true EP0234768A2 (en) 1987-09-02
EP0234768A3 EP0234768A3 (en) 1989-04-26
EP0234768B1 EP0234768B1 (en) 1992-12-09

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Family Applications (1)

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EP87300911A Expired - Lifetime EP0234768B1 (en) 1986-02-17 1987-02-02 Agitator

Country Status (12)

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EP (1) EP0234768B1 (en)
JP (1) JPS62193635A (en)
AT (1) ATE83169T1 (en)
AU (1) AU580702B2 (en)
CA (1) CA1257196A (en)
DE (1) DE3782951T2 (en)
ES (1) ES2037078T3 (en)
GB (1) GB8603904D0 (en)
HK (1) HK1001041A1 (en)
IE (1) IE60597B1 (en)
NZ (1) NZ219280A (en)
ZA (1) ZA87882B (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0441505A1 (en) * 1990-02-05 1991-08-14 Imperial Chemical Industries Plc Agitators
GB2268420A (en) * 1992-07-04 1994-01-12 Flow Research Evaluation Diagn Liquid treatment apparatus
EP0880993A1 (en) * 1997-04-30 1998-12-02 Chemineer, Inc. Impeller assembly with asymmetric concave blades
WO2005012169A1 (en) * 2003-08-01 2005-02-10 Domo Caproleuna Gmbh Method for producing hydroxylammonium salts
WO2008083673A2 (en) * 2007-01-11 2008-07-17 EKATO Rühr- und Mischtechnik GmbH Stirring assembly comprising a stirring element and a gassing device
GB2446924A (en) * 2007-02-16 2008-08-27 Spx Corp Parabolic Radial Flow Impeller
CN102974504A (en) * 2012-12-06 2013-03-20 济南圣泉集团股份有限公司 Anti-sedimentation coating machine
NL2009286C2 (en) * 2012-08-06 2014-02-10 Stichting Energie Swallow tail airfoil.
WO2014121932A1 (en) * 2013-02-07 2014-08-14 Wilfried Rummel Device for producing colloidal fluids, comprising a colloidation container, and method
US11136958B2 (en) 2012-08-06 2021-10-05 Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno Swallow tail airfoil

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003010664A (en) * 2001-07-03 2003-01-14 Kawata Mfg Co Ltd Mixing device for powdery/granular material
CN103958041B (en) * 2011-11-24 2016-10-19 王利 There is the agitator arm of blade paddle shape
JP2014136203A (en) * 2013-01-18 2014-07-28 Chugoku Electric Power Co Inc:The Agitator
JP5898297B2 (en) * 2014-11-20 2016-04-06 グローバルアドバンストメタルジャパン株式会社 Method for producing nitrogen-containing metal powder

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DE2207144A1 (en) * 1972-02-16 1973-08-30 Schoeller Bleckmann Stahlwerke Liquid aerating appts - using vanes with determined gas exit width to vane width ratio
US4305673A (en) * 1980-03-25 1981-12-15 General Signal Corporation High efficiency mixing impeller
EP0224459A2 (en) * 1985-11-21 1987-06-03 Sven Hjort Impeller apparatus

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AU502018B2 (en) * 1976-05-04 1979-07-12 United States Filter Corporation Mixing apparatus
US4159181A (en) * 1976-12-23 1979-06-26 American Pelletizing Corporation Mixing and pelletizing machine
AU509477B2 (en) * 1977-09-05 1980-05-15 Gousti International Ltd. Mixing apparatus
JPS5724624A (en) * 1980-07-18 1982-02-09 Shozo Urashi Vapor-liquid contact apparatus
JPS5759625A (en) * 1980-09-29 1982-04-10 Yoichi Nagase Stirring blade

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
DE2207144A1 (en) * 1972-02-16 1973-08-30 Schoeller Bleckmann Stahlwerke Liquid aerating appts - using vanes with determined gas exit width to vane width ratio
US4305673A (en) * 1980-03-25 1981-12-15 General Signal Corporation High efficiency mixing impeller
EP0224459A2 (en) * 1985-11-21 1987-06-03 Sven Hjort Impeller apparatus

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0441505A1 (en) * 1990-02-05 1991-08-14 Imperial Chemical Industries Plc Agitators
AU639745B2 (en) * 1990-02-05 1993-08-05 Imperial Chemical Industries Plc Agitators
US5246289A (en) * 1990-02-05 1993-09-21 Imperial Chemical Industries Plc Agitator having streamlined blades for reduced cavitation
GB2268420A (en) * 1992-07-04 1994-01-12 Flow Research Evaluation Diagn Liquid treatment apparatus
GB2268420B (en) * 1992-07-04 1995-11-29 Flow Research Evaluation Diagn Improvements relating to liquid treatment apparatus
EP0880993A1 (en) * 1997-04-30 1998-12-02 Chemineer, Inc. Impeller assembly with asymmetric concave blades
KR100826061B1 (en) * 2003-08-01 2008-04-29 도모 카프로로이나 게엠베하 Method for producing hydroxylammonium slats
EA008181B1 (en) * 2003-08-01 2007-04-27 Домо Капролойна Гмбх Method for producing hydroxylammonium salts
WO2005012169A1 (en) * 2003-08-01 2005-02-10 Domo Caproleuna Gmbh Method for producing hydroxylammonium salts
US7608236B2 (en) 2003-08-01 2009-10-27 Domo Caproleuna Gmbh Method for producing hydroxylammonium salts
WO2008083673A2 (en) * 2007-01-11 2008-07-17 EKATO Rühr- und Mischtechnik GmbH Stirring assembly comprising a stirring element and a gassing device
WO2008083673A3 (en) * 2007-01-11 2008-09-18 Ekato Ruehr Mischtechnik Stirring assembly comprising a stirring element and a gassing device
GB2446924A (en) * 2007-02-16 2008-08-27 Spx Corp Parabolic Radial Flow Impeller
NL2009286C2 (en) * 2012-08-06 2014-02-10 Stichting Energie Swallow tail airfoil.
WO2014025252A1 (en) * 2012-08-06 2014-02-13 Stichting Energieonderzoek Centrum Nederland Swallow tail airfoil
US9897067B2 (en) 2012-08-06 2018-02-20 Stichting Energieonderzoek Centrum Nederland Swallow tail airfoil
US11136958B2 (en) 2012-08-06 2021-10-05 Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno Swallow tail airfoil
CN102974504A (en) * 2012-12-06 2013-03-20 济南圣泉集团股份有限公司 Anti-sedimentation coating machine
WO2014121932A1 (en) * 2013-02-07 2014-08-14 Wilfried Rummel Device for producing colloidal fluids, comprising a colloidation container, and method

Also Published As

Publication number Publication date
DE3782951T2 (en) 1993-07-08
ATE83169T1 (en) 1992-12-15
AU6876487A (en) 1987-08-20
HK1001041A1 (en) 1998-05-22
GB8603904D0 (en) 1986-03-26
IE60597B1 (en) 1994-07-27
EP0234768B1 (en) 1992-12-09
EP0234768A3 (en) 1989-04-26
NZ219280A (en) 1988-10-28
JPS62193635A (en) 1987-08-25
IE870279L (en) 1987-08-17
ZA87882B (en) 1987-10-28
ES2037078T3 (en) 1993-06-16
CA1257196A (en) 1989-07-11
DE3782951D1 (en) 1993-01-21
AU580702B2 (en) 1989-01-27

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