EP0577456B1 - Rotatable propeller stirrer - Google Patents

Rotatable propeller stirrer Download PDF

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Publication number
EP0577456B1
EP0577456B1 EP93401535A EP93401535A EP0577456B1 EP 0577456 B1 EP0577456 B1 EP 0577456B1 EP 93401535 A EP93401535 A EP 93401535A EP 93401535 A EP93401535 A EP 93401535A EP 0577456 B1 EP0577456 B1 EP 0577456B1
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EP
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Prior art keywords
blades
axis
planes
principal part
portions
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German (de)
French (fr)
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EP0577456A1 (en
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Joel Bertrand
Martine Poux
Catherine Suereb
Frank Quereux
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Pierre Guerin SA
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Pierre Guerin SA
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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
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/05—Stirrers
    • B01F27/11—Stirrers characterised by the configuration of the stirrers
    • B01F27/113—Propeller-shaped stirrers for producing an axial flow, e.g. shaped like a ship or aircraft propeller

Definitions

  • the present invention relates to propeller agitators consisting of several blades integral with a tree generally disposed vertically in the axis of a container for cause a circulation of the liquid contained in the latter in an axial direction, usually descending in the central zone of the container and ascending in the zone between the latter and the container wall.
  • the blades can be fixed directly on the shaft or be integral with a hub fixed on the shaft.
  • the tree the agitator can be tilted relative to the axis of the container; it can, for example, be arranged horizontally or at an angle in a container with a vertical axis.
  • agitators are used to mix liquids with low viscosity and / or to improve exchanges with the container wall heated or cooled, for example by circulation of a fluid in a double envelope or a coil fixed externally on the wall.
  • parasitic currents in particular radial currents, superimpose on the general axial circulation; these currents are harmful because they decrease the efficiency of the agitator.
  • Document FR-A-1 600 744 refers to a rotary agitator having blades which form a succession of flat elements situated in planes which intersect along straight lines substantially perpendicular to the axis of rotation, forming therebetween angles such as the skew increase from the leading edge to the trailing edge.
  • Document WO-A-91/11620 describes an agitator having blades each having a fold line substantially parallel to the trailing edge, on either side of which extend a flat front part and a flat rear part but angularly deported.
  • the front part is divided by a straight fold line extending from the point of intersection between the blade tip and the first fold line towards the leading edge to define a third flat part which forms an angle d 'inclination in addition to that existing between the first two parts.
  • the aim of the present invention is to propose a new blade profile reducing the importance of the radial currents generated by the rotation of the agitator and, therefore, increase its efficiency.
  • the propeller agitator object of the present invention is defined in claim 1, with any preferred characteristic as defined in the dependent claims. It is formed of blades arranged approximately perpendicular to the axis of the agitator, and which have with respect to a plane perpendicular to the axis of the agitator, a inclination which increases progressively or in stages from the leading edge to the trailing edge, and in that the tip of the blades is bent downstream considering the direction of flow of the liquid displaced by the blades, i.e. down in the most general case where the agitator creates a downward movement of the liquid.
  • the main part of the blades and their end part can be formed each of two portions of planes forming a dihedral whose edge is approximately perpendicular to the axis of the agitator for the main part and is inclined on the horizontal for the terminal part, the two dihedrons connecting to each other in the folding plane.
  • the main part of the blades may also be formed by two portions of planes connected together by a portion of cylinder whose axis is approximately perpendicular to the axis of the agitator, the planes connecting to the cylinder along two generators of the cylinder, and the terminal part may be formed of two portions of planes connecting to the end of the portions of planes of the main part and connected between them by a portion of truncated cone whose generatrices are inclined downstream relative to the generators of the cylinder portion.
  • the leading edge of the main part blades is perpendicular to the axis of the agitator, and the trailing edge of the blades is in a plane perpendicular to the axis of the agitator.
  • the angle formed between the main and terminal parts blades in the bisector plane of the dihedral formed by the plane portions of the part main is between 145 ° and 155 ° and preferably equal to 150 °.
  • the main part of the blades could be tilted slightly downstream, i.e. downwards in case the flow created by the agitator is descending.
  • the agitator shown in Figures 1 to 3 is formed by three identical blades 12 integral with a hub 14 intended to be fixed on a vertical shaft and, angularly spaced from each other by 120 °.
  • the blades could be attached directly to the shaft.
  • the axis 15 of the agitator and, consequently, of the hub 14 is vertical; rotated in the direction indicated by the arrow on the Figure 1, the agitator then creates a downward flow.
  • These blades have a small and substantially constant thickness over their entire surface. They can be formed by cutting, folding and assembling or by stamping sheets or by molding of metals or plastics.
  • Each blade is formed by a main part 16, which is horizontal and attached to the hub 14, and an end portion 18 folded down.
  • Part 16 of the blades has the shape of a dihedral whose edge 23 is perpendicular to the axis of the hub and whose half-planes 20 and 22 are inclined relative to a plane perpendicular to this axis, so that the leading edge 24 of the blade is at a level higher than the trailing edge 26, the inclination of the rear half-plane being greater than that of the half-plane before.
  • the angles of inclination a and b of the half-planes 20 and 22 are approximately 20 ° and 45 ° respectively. These angles can vary from 15 ° to 25 ° and 40 ° at 50 °, respectively.
  • the terminal part of the blade also forms a dihedral whose edge 27 is inclined downwards with respect to the horizontal edge 23 of the main part, the half-planes 28 and 30 of this dihedron being attached to and at an angle with the half-planes 20 and 22.
  • each part of the blades can be formed by cutting and bending a sheet, the two parts being assembled by welding along the line segments 32 and 34 that we can consider it as the folding line of the blade.
  • each blade can be formed from a single sheet suitably cut so that it is possible to fold it along edge 23 and line segments 32 and 34 and to assemble by welding the half-planes 28 and 30 along the edge 27.
  • the main part 16 'of the blades is formed by two portions of planes 20', 22 'connected by a portion cylinder 38 whose axis is perpendicular to the axis 39 of the agitator, the connection taking place along two generatrices of the cylinder.
  • the plane portions 20 ′ and 22 ′ are inclined relative to a plane perpendicular to the hub axis, the angle of inclination of this part of the blades increasing from the leading edge to the trailing edge. (see figure 6).
  • the end portion 18 'of the blades is formed by two portions of planes 28' and 30 ' connected by a portion of truncated cone 40 whose generatrices are inclined by relative to the generators of the cylinder portion 38, so that the tip of the blade either tilted down.
  • Each part of the blades can be formed by cutting and then bending of a sheet, the two parts being assembled by welding along the line 32 ′, 33, 34 'which can be considered as the folding line of the blade since it located at the junction of the horizontal part of the blade and its folded end towards the low.
  • the two portions of planes 28 'and 30' are connected to the portion of truncated cone 40 following two generators.
  • the leading edge 24 'of the main part of the blades and the trailing edge 26 ′ of the blade lie in planes perpendicular to the axis of the hub, except in the area of the blade immediately adjacent to the shaft.
  • the angle formed by the terminal part of the blades with the horizontal part, in the bisector plane of the dihedral formed by the two plane portions 20 ′ and 22 ′, is approximately 150 °, that is to say that, in this plane, the terminal part of the blade makes an angle of about 30 ° with the horizontal; this angle can vary between 145 ° and 155 °.
  • the agitator of the invention makes it possible to reduce notably (from 20 to 35%) the mixing time by absorbing a power of the same order of magnitude than that absorbed by a conventional agitator or significantly lower, depending on the position of the agitator in the container. In some configurations the reduction in mixing time can reach 60%.
  • the blades, or more precisely their main part, attached to the hub could be tilted slightly downward (angle c in Figure 2 slightly higher than 90 °).
  • the invention is not limited to three-blade agitators and also applies to two-blade or more than three-blade agitators.

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  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)
  • Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
  • Apparatus Associated With Microorganisms And Enzymes (AREA)
  • Hydraulic Turbines (AREA)
  • Accessories For Mixers (AREA)

Abstract

Rotary propeller stirrers comprising a number of blades arranged approximately perpendicularly to the stirrer shaft. To reduce the magnitude of the radial currents generated by the rotation of the stirrer and to increase its efficiency, each blade has, in relation to a plane perpendicular to the stirrer axis (15), an inclination (a, b) which increases progressively or in stages from the leading edge (24) to the trailing edge (26) and the end of the blades (28, 30) is folded in the downstream direction, taking into account the direction of flow of the liquid moved by the blades. <IMAGE>

Description

La présente invention a trait aux agitateurs à hélice constitués par plusieurs pales solidaires d'un arbre généralement disposé verticalement dans l'axe d'un récipient pour provoquer une circulation du liquide contenu dans ce dernier suivant une direction axiale, habituellement descendante dans la zone centrale du récipient et ascendante dans la zone comprise entre cette dernière et la paroi du récipient. Les pales peuvent être fixées directement sur l'arbre ou être solidaires d'un moyeu fixé sur l'arbre. Par ailleurs, l'arbre de l'agitateur peut être incliné par rapport à l'axe du récipient; il peut, par exemple, être disposé horizontalement ou en biais dans un récipient à axe vertical. Ces agitateurs sont utilisés pour mélanger des liquides à faible viscosité et/ou pour améliorer les échanges thermiques avec la paroi du récipient chauffée ou refroidie, par exemple par circulation d'un fluide dans une double enveloppe ou un serpentin fixé extérieurement sur la paroi. Avec ce type d'agitateur, des courants parasites, notamment des courants radiaux, se superposent à la circulation générale axiale; ces courants sont nuisibles parce qu'ils diminuent l'efficacité de l'agitateur. The present invention relates to propeller agitators consisting of several blades integral with a tree generally disposed vertically in the axis of a container for cause a circulation of the liquid contained in the latter in an axial direction, usually descending in the central zone of the container and ascending in the zone between the latter and the container wall. The blades can be fixed directly on the shaft or be integral with a hub fixed on the shaft. By the way, the tree the agitator can be tilted relative to the axis of the container; it can, for example, be arranged horizontally or at an angle in a container with a vertical axis. These agitators are used to mix liquids with low viscosity and / or to improve exchanges with the container wall heated or cooled, for example by circulation of a fluid in a double envelope or a coil fixed externally on the wall. With this type of agitator, parasitic currents, in particular radial currents, superimpose on the general axial circulation; these currents are harmful because they decrease the efficiency of the agitator.

"L'art antérieur, à cet égard, peut être illustré, notamment par les enseignements des documents FR-A-1 600 744 et WO-A-91 11 620."The prior art, in this regard, can be illustrated, in particular by the teachings of documents FR-A-1 600 744 and WO-A-91 11 620 .

Le document FR-A-1 600 744 se référe à un agitateur rotatif possédant des pales qui forment une succession d'éléments plats situés dans des plans qui s'intersectent suivant des droites substantiellement perpendiculaires à l'axe de rotation en formant entre-eux des angles tels que l'obliquité augmente depuis le bord d'attaque jusqu'au bord de fuite.Document FR-A-1 600 744 refers to a rotary agitator having blades which form a succession of flat elements situated in planes which intersect along straight lines substantially perpendicular to the axis of rotation, forming therebetween angles such as the skew increase from the leading edge to the trailing edge.

Le document WO-A-91/11620 décrit un agitateur possédant des pales ayant chacune une ligne de pliage sensiblement parallèle au bord de fuite, de part et d'autre de laquelle s'étendent une partie frontale plate et une partie arrière plate mais angulairement déportée. La partie frontale est divisée par une ligne de pliage rectiligne s'étendant à partir du point d'intersection entre l'extrémité de pale et la première ligne de pliage vers le bord d'attaque pour définir une troisième partie plate qui forme un angle d'inclinaison venant s'ajouter à celui existant entre les deux premières parties.Document WO-A-91/11620 describes an agitator having blades each having a fold line substantially parallel to the trailing edge, on either side of which extend a flat front part and a flat rear part but angularly deported. The front part is divided by a straight fold line extending from the point of intersection between the blade tip and the first fold line towards the leading edge to define a third flat part which forms an angle d 'inclination in addition to that existing between the first two parts.

Cette disposition est présentée comme favorable pour améliorer la circulation axiale du liquide lors de la rotation de l'agitateur". This provision is presented as favorable for improving the axial circulation of the liquid when rotating the agitator ".

Le but de la présente invention est de proposer un nouveau profil de pale permettant de réduire l'importance des courants radiaux engendrés par la rotation de l'agitateur et, par conséquent, d'augmenter son efficacité.The aim of the present invention is to propose a new blade profile reducing the importance of the radial currents generated by the rotation of the agitator and, therefore, increase its efficiency.

L'agitateur à hélice objet de la présente invention est défini dans la revendication 1, avec toute caractéristique préférée telle que définie dans les revendications dépendentes. Il est formé de pales disposées approximativement perpendiculairement à l'axe de l'agitateur, et qui présentent par rapport à un plan perpendiculaire à l'axe de l'agitateur, une inclinaison qui croít progressivement ou par paliers du bord d'attaque au bord de fuite, et en ce que le bout des pales est plié vers l'aval en considérant le sens d'écoulement du liquide déplacé par les pales, c'est-à-dire vers le bas dans le cas le plus général où l'agitateur crée un mouvement descendant du liquide.The propeller agitator object of the present invention is defined in claim 1, with any preferred characteristic as defined in the dependent claims. It is formed of blades arranged approximately perpendicular to the axis of the agitator, and which have with respect to a plane perpendicular to the axis of the agitator, a inclination which increases progressively or in stages from the leading edge to the trailing edge, and in that the tip of the blades is bent downstream considering the direction of flow of the liquid displaced by the blades, i.e. down in the most general case where the agitator creates a downward movement of the liquid.

La partie principale des pales et leur partie terminale pourront être formées chacune de deux portions de plans formant un dièdre dont l'arête est approximativement perpendiculaire à l'axe de l'agitateur pour la partie principale et est inclinée sur l'horizontale pour la partie terminale, les deux dièdres se raccordant l'un à l'autre dans le plan de pliage.The main part of the blades and their end part can be formed each of two portions of planes forming a dihedral whose edge is approximately perpendicular to the axis of the agitator for the main part and is inclined on the horizontal for the terminal part, the two dihedrons connecting to each other in the folding plane.

La partie principale des pales pourra aussi être formée de deux portions de plans raccordés entre eux par une portion de cylindre dont l'axe est approximativement perpendiculaire à l'axe de l'agitateur, les plans se raccordant au cylindre le long de deux génératrices du cylindre, et la partie terminale pourra être formée de deux portions de plans se raccordant à l'extrémité des portions de plans de la partie principale et raccordés entre eux par une portion de tronc de cône dont les génératrices sont inclinées vers l'aval par rapport aux génératrices de la portion de cylindre.The main part of the blades may also be formed by two portions of planes connected together by a portion of cylinder whose axis is approximately perpendicular to the axis of the agitator, the planes connecting to the cylinder along two generators of the cylinder, and the terminal part may be formed of two portions of planes connecting to the end of the portions of planes of the main part and connected between them by a portion of truncated cone whose generatrices are inclined downstream relative to the generators of the cylinder portion.

Suivant une forme de réalisation préférée, le bord d'attaque de la partie principale des pales est perpendiculaire à l'axe de l'agitateur, et le bord de fuite des pales se trouve dans un plan perpendiculaire à l'axe de l'agitateur.According to a preferred embodiment, the leading edge of the main part blades is perpendicular to the axis of the agitator, and the trailing edge of the blades is in a plane perpendicular to the axis of the agitator.

De préférence, l'angle que forment entre elles les parties principale et terminale des pales dans le plan bissecteur du dièdre formé par les portions de plans de la partie principale est compris entre 145° et 155° et de préférence égal à 150°.Preferably, the angle formed between the main and terminal parts blades in the bisector plane of the dihedral formed by the plane portions of the part main is between 145 ° and 155 ° and preferably equal to 150 °.

Au lieu d'être perpendiculaire à l'axe de l'agitateur , la partie principale des pales pourrait être légèrement inclinée vers l'aval, c'est-à-dire vers le bas dans le cas où l'écoulement créé par l'agitateur est descendant.Instead of being perpendicular to the axis of the agitator, the main part of the blades could be tilted slightly downstream, i.e. downwards in case the flow created by the agitator is descending.

La description qui suit se réfère aux dessins l'accompagnant qui montrent, à titre d'exemple non-limitatif, deux formes de réalisation de l'invention et sur lesquels :

  • La figure 1 est une vue en plan d'une hélice tripale conforme à l'invention;
  • La figure 2 est une vue de face de l'une des pales;
  • La figure 3 est une vue en bout de l'une des pales;
  • La figure 4 est une vue en plan d'une pale d'un autre agitateur conforme à l'invention;
  • La figure 5 est une vue de face de la pale de la figure 4; et
  • La figure 6 est une vue en bout de la pale de la figure 4.
    • The following description refers to the accompanying drawings which show, by way of non-limiting example, two embodiments of the invention and in which:
  • Figure 1 is a plan view of a three-bladed propeller according to the invention;
  • Figure 2 is a front view of one of the blades;
  • Figure 3 is an end view of one of the blades;
  • Figure 4 is a plan view of a blade of another agitator according to the invention;
  • Figure 5 is a front view of the blade of Figure 4; and
  • FIG. 6 is an end view of the blade of FIG. 4.

    • L'agitateur représenté sur les figures 1 à 3 est formé de trois pales identiques 12 solidaires d'un moyeu 14 destiné à être fixé sur un arbre vertical et, angulairement espacées l'une de l'autre de 120°. Les pales pourraient être fixées directement sur l'arbre. Dans la description qui suit, on suppose que l'axe 15 de l'agitateur et, par conséquent, du moyeu 14 est vertical; entraíné en rotation dans le sens indiqué par la flèche sur la figure 1, l'agitateur crée alors un écoulement descendant.The agitator shown in Figures 1 to 3 is formed by three identical blades 12 integral with a hub 14 intended to be fixed on a vertical shaft and, angularly spaced from each other by 120 °. The blades could be attached directly to the shaft. In the description which follows, it is assumed that the axis 15 of the agitator and, consequently, of the hub 14 is vertical; rotated in the direction indicated by the arrow on the Figure 1, the agitator then creates a downward flow.

    Ces pales ont une épaisseur faible et sensiblement constante sur toute leur surface. Elles peuvent être formées par découpage, pliage et assemblage ou par emboutissage de tôles ou par moulage de métaux ou matières plastiques.These blades have a small and substantially constant thickness over their entire surface. They can be formed by cutting, folding and assembling or by stamping sheets or by molding of metals or plastics.

    Chaque pale est formée d'une partie principale 16, qui est horizontale et attachée au moyeu 14, et d'une partie terminale 18 pliée vers le bas. La partie 16 des pales a la forme d'un dièdre dont l'arête 23 est perpendiculaire à l'axe du moyeu et dont les demi-plans 20 et 22 sont inclinés par rapport à un plan perpendiculaire à cet axe, de telle sorte que le bord d'attaque 24 de la pale se trouve à un niveau supérieur au bord de fuite 26, l'inclinaison du demi-plan arrière étant supérieure à celle du demi-plan avant. Dans la forme de réalisation décrite, les angles d'inclinaison a et b des demi-plans 20 et 22 sont respectivement d'environ 20° et 45°. Ces angles peuvent varier de 15° à 25° et de 40° à 50°, respectivement.Each blade is formed by a main part 16, which is horizontal and attached to the hub 14, and an end portion 18 folded down. Part 16 of the blades has the shape of a dihedral whose edge 23 is perpendicular to the axis of the hub and whose half-planes 20 and 22 are inclined relative to a plane perpendicular to this axis, so that the leading edge 24 of the blade is at a level higher than the trailing edge 26, the inclination of the rear half-plane being greater than that of the half-plane before. In the described embodiment, the angles of inclination a and b of the half-planes 20 and 22 are approximately 20 ° and 45 ° respectively. These angles can vary from 15 ° to 25 ° and 40 ° at 50 °, respectively.

    La partie terminale de la pale forme aussi un dièdre dont l'arête 27 est inclinée vers le bas par rapport à l'arête horizontale 23 de la partie principale, les demi-plans 28 et 30 de ce dièdre étant rattachés aux demi-plans 20 et 22 et faisant un angle avec ceux-ci.The terminal part of the blade also forms a dihedral whose edge 27 is inclined downwards with respect to the horizontal edge 23 of the main part, the half-planes 28 and 30 of this dihedron being attached to and at an angle with the half-planes 20 and 22.

    Chaque partie des pales peut être formée par découpage et pliage d'une tôle, les deux parties étant assemblées par soudage le long des segments de droite 32 et 34 que l'on peut considérer comme la ligne de pliage de la pale. En variante, chaque pale peut être formée à partir d'une tôle unique convenablement découpée, de telle sorte qu'il soit possible de la plier le long de l'arête 23 et des segments de droite 32 et 34 et d'assembler par soudage les demi-plans 28 et 30 le long de l'arête 27.Each part of the blades can be formed by cutting and bending a sheet, the two parts being assembled by welding along the line segments 32 and 34 that we can consider it as the folding line of the blade. Alternatively, each blade can be formed from a single sheet suitably cut so that it is possible to fold it along edge 23 and line segments 32 and 34 and to assemble by welding the half-planes 28 and 30 along the edge 27.

    Dans la forme de réalisation représentée sur les figures 4 à 6, la partie principale 16' des pales est formée de deux portions de plans 20', 22' raccordées par une portion de cylindre 38 dont l'axe est perpendiculaire à l'axe 39 de l'agitateur, le raccordement s'effectuant le long de deux génératrices du cylindre. Comme dans la première forme de réalisation, les portions de plans 20' et 22' sont inclinées par rapport à un plan perpendiculaire à l'axe du moyeu, l'angle d'inclinaison de cette partie des pales augmentant du bord d'attaque au bord de fuite. (voir figure 6).In the embodiment shown in Figures 4 to 6, the main part 16 'of the blades is formed by two portions of planes 20', 22 'connected by a portion cylinder 38 whose axis is perpendicular to the axis 39 of the agitator, the connection taking place along two generatrices of the cylinder. As in the first form of embodiment, the plane portions 20 ′ and 22 ′ are inclined relative to a plane perpendicular to the hub axis, the angle of inclination of this part of the blades increasing from the leading edge to the trailing edge. (see figure 6).

    La partie terminale 18' des pales est formée de deux portions de plans 28' et 30' raccordées par une portion de tronc de cône 40 dont les génératrices sont inclinées par rapport aux génératrices de la portion de cylindre 38, de telle sorte que le bout de la pale soit incliné vers le bas. Chaque partie des pales peut être formée par découpage puis cintrage d'une tôle, les deux parties étant assemblées par soudage le long de la ligne 32', 33, 34' que l'on peut considérer comme la ligne de pliage de la pale puisqu'elle se trouve à la jonction de la partie horizontale de la pale et de son extrémité pliée vers le bas. Les deux portions de plans 28' et 30' se raccordent à la portion de tronc de cône 40 suivant deux génératrices.The end portion 18 'of the blades is formed by two portions of planes 28' and 30 ' connected by a portion of truncated cone 40 whose generatrices are inclined by relative to the generators of the cylinder portion 38, so that the tip of the blade either tilted down. Each part of the blades can be formed by cutting and then bending of a sheet, the two parts being assembled by welding along the line 32 ′, 33, 34 'which can be considered as the folding line of the blade since it located at the junction of the horizontal part of the blade and its folded end towards the low. The two portions of planes 28 'and 30' are connected to the portion of truncated cone 40 following two generators.

    Dans cette forme de réalisation, le bord d'attaque 24' de la partie principale des pales et le bord de fuite 26'de la pale se trouvent dans des plans perpendiculaires à l'axe du moyeu, sauf dans la zone de la pale immédiatement adjacente à l'arbre. L'angle formé par la partie terminale des pales avec la partie horizontale, dans le plan bissecteur du dièdre formé par les deux portions de plan 20' et 22', est d'environ 150°, c'est-à-dire que, dans ce plan, la partie terminale de la pale fait un angle d'environ 30° avec l'horizontale; cet angle peut varier entre 145° et 155°.In this embodiment, the leading edge 24 'of the main part of the blades and the trailing edge 26 ′ of the blade lie in planes perpendicular to the axis of the hub, except in the area of the blade immediately adjacent to the shaft. The angle formed by the terminal part of the blades with the horizontal part, in the bisector plane of the dihedral formed by the two plane portions 20 ′ and 22 ′, is approximately 150 °, that is to say that, in this plane, the terminal part of the blade makes an angle of about 30 ° with the horizontal; this angle can vary between 145 ° and 155 °.

    Le tableau suivant met en évidence les performances supérieures de l'agitateur des figures 4 à 6 par rapport à celles d'un agitateur classique à pales droites dans des conditions d'essai comparables.

    Figure 00060001
    The following table highlights the superior performance of the agitator of FIGS. 4 to 6 compared to that of a conventional agitator with straight blades under comparable test conditions.
    Figure 00060001

    Dans ce tableau :

    h / H
    définit la position en hauteur relative de l'agitateur dans le récipient d'essai,
    Np
    est un facteur sans dimension qui est une image de la puissance absorbée.
    Np
    = P/ .N3.D5
    P
    = puissance absorbée par l'agitateur
    = masse volumique du liquide
    N
    = vitesse de rotation de l'agitateur
    D
    = diamètre de l'agitateur
    et N.tm est un facteur sans dimension qui est une image du temps de mélange.In this table :
    h / h
    defines the relative height position of the agitator in the test container,
    Np
    is a dimensionless factor which is an image of the power absorbed.
    Np
    = P / .N 3 .D 5
    P
    = power absorbed by the agitator
    = density of the liquid
    NOT
    = speed of rotation of the agitator
    D
    = agitator diameter
    and N.tm is a dimensionless factor which is an image of the mixing time.

    On voit sur ce tableau que l'agitateur de l'invention permet de réduire notablement (de 20 à 35 %) le temps de mélange en absorbant une puissance du même ordre de grandeur que celle absorbée par un agitateur classique ou nettement inférieure, suivant la position de l'agitateur dans le récipient. Dans certaines configurations particulières, la réduction du temps de mélange peut atteindre 60 %.We see on this table that the agitator of the invention makes it possible to reduce notably (from 20 to 35%) the mixing time by absorbing a power of the same order of magnitude than that absorbed by a conventional agitator or significantly lower, depending on the position of the agitator in the container. In some configurations the reduction in mixing time can reach 60%.

    Au lieu d'être horizontales, les pales, ou plus précisément leur partie principale, rattachée au moyeu, pourrait être légèrement inclinée vers le bas (angle c de la figure 2 légèrement supérieur à 90°).Instead of being horizontal, the blades, or more precisely their main part, attached to the hub, could be tilted slightly downward (angle c in Figure 2 slightly higher than 90 °).

    L'invention n'est pas limitée aux agitateurs à trois pales et s'applique aussi aux agitateurs à deux pales ou à plus de trois pales.The invention is not limited to three-blade agitators and also applies to two-blade or more than three-blade agitators.

    Claims (7)

    1. Rotating propeller mixer defining an axis of rotation and comprising a plurality of identical blades each comprising, on the one hand, a principal part approximately perpendicular to said axis of rotation, directly or indirectly connected to this axis and presenting, with respect to a plane perpendicular to the axis of rotation, an inclination to provoke a circulation in an axial direction and, on the other hand, a terminal part located opposite said axis of rotation, characterized in that this terminal part, over the whole of its width, is bent towards downstream, considering the direction of axial circulation of the liquid produced by the rotation of the mixer, in order to reduce the magnitude of the radial currents generated by this rotation.
    2. Propeller mixer according to Claim 1, characterized in that the principal part (16) of the blades is formed by two portions of planes (20, 22) forming a dihedron of which the edge (23) is approximately perpendicular to the axis of the mixer, and the terminal part (18) of the blades is likewise formed by two portions of planes (28, 30) joined to the end of the principal part and forming a dihedron of which the edge (27) is inclined towards downstream with respect to the edge of the principal part.
    3. Propeller mixer according to Claim 1, characterized in that the principal part (16') of the blades is formed by two portions of planes (20', 22') which are joined together by a portion of cylinder (38) of which the axis is approximately perpendicular to the axis of the mixer, the planes joining the cylinder along two generatrices of the cylinder, and in that the terminal part of the blades is formed by two portions of planes (28', 30') connected to the end of the portions of planes of the principal part and connected together by a portion of frustum of cone (40) of which the generatrices are inclined towards downstream with respect to the generatrices of the portion of cylinder.
    4. Propeller mixer according to Claim 1, 2 or 3, characterized in that the angle formed by the principal and terminal parts of the blades in the bisecting plane of the dihedron formed by the two portions of plane of the principal part is included between 145° and 155° and, preferably, equal to 150°.
    5. Propeller mixer according to any one of the preceding Claims, characterized in that the leading edge of the principal part of the blades is perpendicular to the axis of the mixer.
    6. Propeller mixer according to any one of the preceding Claims, characterized in that the trailing edge of the blades lies in a plane perpendicular to the axis of the mixer.
    7. Propeller mixer according to any one of the preceding Claims, characterized in that the principal part of the blades is slightly inclined towards downstream.
    EP93401535A 1992-06-30 1993-06-16 Rotatable propeller stirrer Expired - Lifetime EP0577456B1 (en)

    Applications Claiming Priority (2)

    Application Number Priority Date Filing Date Title
    FR9208010A FR2692809B1 (en) 1992-06-30 1992-06-30 Rotary propeller agitator.
    FR9208010 1992-06-30

    Publications (2)

    Publication Number Publication Date
    EP0577456A1 EP0577456A1 (en) 1994-01-05
    EP0577456B1 true EP0577456B1 (en) 1999-01-13

    Family

    ID=9431334

    Family Applications (1)

    Application Number Title Priority Date Filing Date
    EP93401535A Expired - Lifetime EP0577456B1 (en) 1992-06-30 1993-06-16 Rotatable propeller stirrer

    Country Status (6)

    Country Link
    EP (1) EP0577456B1 (en)
    AT (1) ATE175588T1 (en)
    DE (1) DE69323004T2 (en)
    DK (1) DK0577456T3 (en)
    ES (1) ES2128399T3 (en)
    FR (1) FR2692809B1 (en)

    Families Citing this family (6)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    DE4401596A1 (en) * 1994-01-20 1995-07-27 Ekato Ruehr Mischtechnik Stirrer
    US6054563A (en) * 1997-03-05 2000-04-25 Rhodia Chimie Preparation of solid, powdery rare earth carboxylates by evaporation method
    DE19709818B4 (en) * 1997-03-10 2007-09-27 Wilo Ag submersible agitator
    US6090926A (en) * 1998-06-05 2000-07-18 Rhodia Rare Earths Inc. Powdery, solid rare earth carboxylates with improved solubility in aliphatic solvents which are highly active catalysts in Ziegler-Natta systems
    FI123826B (en) * 2012-02-20 2013-11-15 Outotec Oyj Blades for an axial impeller and axial impeller
    ES2860465T3 (en) * 2014-04-04 2021-10-05 Milton Roy Europe Shaking mobile

    Family Cites Families (3)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    FR1600744A (en) * 1968-12-11 1970-07-27
    FR2313114A1 (en) * 1975-06-04 1976-12-31 Procedes Sem NEW IMPROVEMENTS TO PROPELLERS FOR MIXERS
    US5052892A (en) * 1990-01-29 1991-10-01 Chemineer, Inc. High efficiency mixer impeller

    Also Published As

    Publication number Publication date
    ES2128399T3 (en) 1999-05-16
    EP0577456A1 (en) 1994-01-05
    DE69323004D1 (en) 1999-02-25
    FR2692809A1 (en) 1993-12-31
    DE69323004T2 (en) 1999-06-24
    FR2692809B1 (en) 1994-11-25
    ATE175588T1 (en) 1999-01-15
    DK0577456T3 (en) 1999-09-06

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