FR2746326A1 - ANNULAR TRAY MIXER - Google Patents

Abstract

An annular tank mixer comprises a plurality of mixing tools which are joined in respective pairs: an inner mixing tool (8b) is associated, at a given angular distance, with an outer mixing tool (8a). At least one of the mixing tools of each pair has, in its projection in the radial direction, an extent which is equal to at least 40% of the width of the mixing chamber (1). In addition, the mixing tools are preferably inclined relative to the vertical at an angle of between 20 and 45 deg. Overall, the mixing tools of each pair thus assist in their mixing action, which provides shorter mixing times with satisfactory intimate mixing, exhibiting a smaller coefficient of variation.

Description

D E S C R I P T I O N

  The present invention relates to an annular tank mixer, with a) a housing, in which is configured an annular mixing chamber delimited by an external tank wall, an internal tank wall and a bottom, b) a rotor rotary to which is fixed, by means of a plurality of mixing arms extending in the mixing chamber, a plurality of mixing tools arranged at different radial distances from the center of rotation, the external mixing tools being angularly inclined, by with respect to the radial direction, so that they give the mixed product a component of movement radially inward, and the interior mixing tools being angularly inclined, with respect to the radial direction, so that they give the mixed product

  radially outward movement component.

  Mixers are known in different construction modes for producing hydraulically linked products, for example concrete, mortar, etc. We differentiate in particular the types of construction working with a horizontal shaft from those in which the mixing tools rotate around a vertical axis. The first method of construction is certainly distinguished by an excellent mixing result, but it comes with costs

  relatively high and requires a great height of construction.

  Annular tank mixers of the type mentioned in the introduction, which are of the second construction method, have a lower yield than mixers with a horizontal shaft and therefore require longer mixing times. Their mixing arms are generally distributed at constant angular intervals over the annular mixing chamber, with alternating external and internal mixing tools. The mixing tools each have a relatively short range in projection in the radial direction, and they work on narrow paths. The result is that the successive mixing tools in the direction of movement are "uncoupled" in their action insofar as each of these tools no longer perceives the action of the previous mixing tool, since the movement of the product mixed which had been produced by this tool is already largely dissipated. In addition, the mixing tools, placed vertically or at a small angle of inclination relative to the bottom of the mixing chamber, mainly produce a movement of the mixed product only in the radial direction; product movement in

  vertical direction is largely left to chance.

  The object of the present invention is to configure an annular tank mixer of the type mentioned in the introduction so that its mixing action is as good or even better than that of a horizontal shaft mixer, while retaining the cost advantages and the low height

  of construction which are known for annular tank mixers.

  According to the invention, this object is achieved by the fact that: c) the mixing tools are respectively provided in pairs, each comprising an external mixing tool close to the external wall of the tank and an internal mixing tool close to the internal wall of the tank , d) at least one of the mixing tools of each pair has, in its projection on the radial direction, an extent at least equal to 40% of the width of the mixing chamber, e) the angular distance between the mixing tools of each successive pairs in the direction of movement is chosen so that the front mixing tool in the direction of movement directs the flow of mixed product on the rear mixing tool in the direction of movement. With the present invention, we are trying for the first time to obtain, by a directed association of two successive mixing tools, one of which is an exterior mixing tool and the other of which is an interior mixing tool, defined forced models of product movement. mixed, at least the two mixing tools of the pair assisting each other. This is notably obtained by giving at least one mixing tool of the pair, in projection on the radial direction, a much greater extent than was the case in the prior art. If this extent is at least equal to 40% of the width of the mixing chamber, flows of mixed product are obtained which can be directed from the front mixing tool in the direction of movement on the rear mixing tool in the direction displacement, and whose configuration can therefore be controlled. Care must be taken here to respect a corresponding angular distance between the two mixing tools of the pair. On the whole, flows of mixed product are obtained in this way which provide, in a much shorter mixing time, much more homogeneous mixtures with coefficients of variation lower than what could be obtained with known mixers.

annular tank.

  Preferably, it is the external mixer tool which, in its projection on the radial direction, has a greater extent than the internal mixer tool. The external mixing tool is thus provided with a more powerful circulation action, which is provided because this action must

oppose centrifugal force.

  According to a particularly advantageous embodiment of the invention, the sum of the expanses, projected on the radial direction, of the two mixing tools of each pair is approximately equal to the width of the mixing chamber. This guarantees that each pair of mixing tools covers the entire width of the mixing chamber, without the possibility

  avoidance for the mixed product.

  In order to also be able to better act on the vertical movement of the mixed product, it is recommended, according to an additional configuration of the invention, that each mixing tool be inclined relative to the vertical by an angle between 20 and 45, so as to to facilitate its overflow by the mixed product. On each mixing tool, the mixed product therefore receives a movement component not only in the radial direction, but also, in addition, in the vertical direction. This creates intersecting motion patterns that accelerate even more

  homogenization of the mixed product.

  Preferably, the angle in question is between 30 and 35.

  In many cases, it can be recommended that each external mixing tool has, in the region close to the external wall of the tank, a greater height than in the region located radially more inside. Indeed, we do not want the mixer tool to overflow directly onto the external wall of the tank: here, it is mainly important to evacuate the mixed product from the external wall of the tank radially towards

  the interior as quickly and efficiently as possible.

  For the same reason, it is recommended that each external mixing tool extends vertically on its edge close to the external wall of the tank, while it is inclined at a certain angle relative to the vertical in a region located radially more inside. The "overflow" of the external mixer tool therefore only begins at one

  certain radial distance from the outer wall of the tank.

  Depending on the consistency of the mixed product, it may be particularly advantageous to provide a configuration according to which the height of the external mixing tools has, at a given distance from the external wall of the tank, a minimum from which it increases in both directions. The increase in height radially inward from the minimum has the consequence that the overflow is more difficult in the regions of the mixing tool located radially more inside, than in the vicinity of the minimum height. The partial flow of mixed product which overflows from the mixing tool in the region of the minimum height thus sinks "under cover" of the higher region, located more inside, of the mixing tool, which can generate a spiral guidance of the movement of this partial flow. This also contributes, by activating the shearing forces, to a stronger mixing of the product in a shorter time. Given that the mixing arms must necessarily sink at least partially into the mixed product, it is recommended to provide a configuration of the invention according to which at least one protection against wear is formed on the mixing tools, protection which surrounds the region of the mixing arm which extends into the mixed product, at least on the side where the mixed product flows. The mixing arms thus reach durations

longer operating times.

  At least part of the mixing tools can be composed of segments. This facilitates the manufacture, assembly, maintenance and

  replacement of mixing tools.

  If the segments are at least partially independent parts, they can perform corresponding independent avoidance movements. These avoidance movements are necessary to avoid blockages when the mixing tools come up against obstacles on the bottom of the mixing chamber, for example on components more

of the mixed product.

  The segments can be, in their normal working position, contiguous by lateral edges. As long as the segments are not separated from each other for a particular reason, mixing tools thus configured do not differ, in their mixing function

  proper, one-piece mixing tools.

  However, in many cases it is particularly advantageous for the mixing action that slots remain between the lateral edges of the segments, slots through which partial flows of mixed product can pass, but which are sufficiently narrow for the The entire mixing tool retains its overall unitary function. These slots provide additional possibilities as to how the mixed product can partially flow through the mixing tool, without having to overflow it, which also contributes to the diversity of movement of the

mixed product.

  The three-dimensional nature of the movement of the mixed product can be even more favored by an exemplary embodiment of the invention according to which at least one auxiliary blade is mounted vertically, at a distance above the mixing tool, on the region of at least minus one mixing arm which sinks into the mixed product, a blade which is inclined relative to the vertical so that it pushes the mixed product down. The actual mixing tool and the auxiliary blade arranged above therefore have "antagonistic" actions, insofar as these actions tend to displace the

  product mixed vertically in opposite directions.

  It may be advantageous for at least one mixing tool to be provided, at an apex, with a stirrup piece made of a material with high wear resistance, which evacuates the edge between the bottom and the wall of the neighboring tank. Indeed, this top is exposed to a particularly strong wear, which is received by the stirrup piece (which can be replaceable). The longevity of the whole tool

mixer is thus increased.

  It is particularly appropriate to provide a configuration of the invention according to which each mixing arm comprises: a) at least one carrying shaft rotatably mounted on the rotor, b) at least one connecting arm fixed on the carrying shaft, arm which extends into the

  mixing chamber and at the end of which is fixed a mixing tool.

  The avoidance movement that the mixing tool accomplishes when encountering an obstacle on the bottom of the mixing chamber is therefore effected by the fact that the carrier shaft rotates around its axis. The link arm is then pivoted so that the mixing tool moves on an arc of

  circle between its position close to the bottom and a slightly higher position.

  The simplest is that the carrier shaft extends substantially horizontally. However, during its avoidance movement, the mixing tool will less easily collide with the neighboring tank wall if the associated carrier shaft does not extend exactly horizontally. The carrier shaft of each longer mixing arm should be inclined relative to the horizontal, so that it is higher at its radially outer end than at its radially inner end. On the other hand, the carrier shaft of each shorter mixing arm should be inclined, with respect to the horizontal, so that it is higher at its radially inner end than at its radially outer end. During an avoidance movement, the mixing tools thus move away from the neighboring tank wall. In the normal working position, the slot between the wall

  and the mixing tool can be kept particularly small.

  The bearing for the carrier shaft should have a rotation stop, ensuring that a minimum distance remains between the mixing tool and the bottom of the mixing chamber. The underside of the mixing tool should therefore not normally be applied directly against the

bottom of the mixing chamber.

  In favorable cases, the reaction force, which comes from the interaction between the mixing tool inclined with respect to the vertical and the mixed product, is sufficient to hold the carrier shaft against its rotation stop, and therefore the tool mixer in its position close to the bottom. It is only exceptionally that it may be necessary to provide a device for

  spring, which presses the carrier shaft in the direction of the rotation stop.

  Each carrier shaft should form an angle other than 90 with the tangential plane passing through its point of attachment to the rotor. If this geometrical condition is not respected, it can happen that the mixing tool

  locks against the tank wall during its avoidance movement.

  Since a mixing tool is made up of independent segments, as explained above, it is recommended that a separate mixing arm be associated with each of these independent segments. This can be done by the fact that a separate bearing shaft, mounted for rotation on the rotor, is associated with each independent segment of a mixing tool, all the bearing shafts of the segments forming part of a mixing tool being arranged coaxially. and at least the outer bearing shaft (s) being made hollow. The different segments of the mixing tool are therefore "suspended" from load-bearing telescopic shafts, one on the other.

  others, which is particularly space-saving and easy to maintain.

  If necessary, a separate spring device can be associated with each of the coaxial bearing shafts, device which presses the shaft

  carrier against its own rotation stop.

  Preferably, each link arm is a plate-shaped element, on the narrow side from which the mixed product can flow. The link arm thus receives, on the one hand, maximum stability; on the other hand, this minimizes wear on the link arm as well as resistance to displacement

  produced by the link arm when the rotor rotates.

  The already remarkable mixing action which can be obtained in the manner described above can be further improved by the fact that at least one cyclone is fixed on the rotor between two neighboring pairs of mixing arms. The position of this cyclone is chosen so that it is located in the region of incoming flow of the anterior mixing tool in the direction of

displacement.

  Basically, the cyclone can have its own drive (electric, hydraulic or other). However, it is particularly advantageous for the cyclone drive to comprise: a) a toothed wheel coaxial with the axis of rotation of the rotor, but stationary, b) a toothed wheel mounted on the rotor, meshing with the stationary toothed wheel and assembled in rotation solidarity with a first coaxial belt pulley, c) a second belt pulley, rotatable in conjunction with the tools of the cyclone, d) an endless drive element, for example an endless belt,

  connecting the two pulleys together.

  In this configuration of the invention, the rotation of the tools of the cyclone is taken from the rotation of the rotor around the stationary central gear. The tools of the cyclone are rotated here against the flow of the material. The speed of rotation of the cyclone can be easily modified and adapted to the respective particularities, by correspondingly modifying the sizes of the pulleys over which the endless drive element passes. This can be achieved in a few manipulations. The following description describes in more detail embodiments of the invention using the accompanying drawings, in which: FIG. 1 is a top view of an annular tank mixer with the covering cap and the rotor cover removed, Figure 2 is a vertical sectional view through the annular tray mixer of Figure 1, Figure 3 schematically shows the angular position of a mixing tool of the annular tray mixer of Figure 1 relative to at the bottom of the mixing chamber, FIGS. 4 to 8 represent different embodiments of mixing tools which can be used for the annular tank mixer of FIG. 1, FIGS. 9 and 10 are views in vertical section, similar in Figure 2, through a second embodiment of an annular tank mixer. The annular tank mixer shown in FIGS. 1 and 2 has an annular mixing chamber 1, which is delimited by an external wall of tank 2, an internal wall of tank 3 and a bottom 4. The walls of tank 2 and 3 thus that the bottom 4 are provided with a wear-resistant covering, which

  is not expressly shown in the figures.

  The space surrounded by the inner wall of tank 3 is reserved for the drive elements of a rotor 5, which covers this space upwards. The rotor 5 is a part open upwards, in the form of a bucket in rough approximation, which comprises a bottom 5a and a cylindrical wall 5b. Space

  inside the rotor 5 is closed upwards by a removable cover 6.

  A plurality of mixing arms 7 projecting radially outward is fixed in the cylindrical wall 5b of the rotor 5. As shown in particular in FIG. 1, these mixing arms 7 do not extend radially towards the center of the rotor 5, but they form a respectively acute or obtuse angle with the tangential plane passing through the point of attachment of the respective mixing arm 7 on the inner wall of tank 3. We will come back to the

significance of this measure.

  The mixing arms 7 are provided in respective pairs 7a, 7b.

  In the embodiment of an annular tank mixer which is shown in the drawing, two pairs 7a, 7b are provided which are arranged in point symmetry with respect to the center of the mixer. The respectively longer mixing arm 7a is used to hold and guide an external mixing tool 8a, while the respectively shorter mixing arm 7b of the

  pair is used to hold and guide an interior mixing tool 8b.

  The mixing arms 7 each comprise a horizontal support shaft 9 which is hollow for reasons of no interest here, the support shafts 9 being kept in rotation in bearings 10 on the cylindrical wall 5b. At least one connecting arm 11 in the form of a plate, extending downwards in the mixing chamber 1, is fixed to each carrying shaft 9, arm on which the mixing tool 8 respectively associated is itself mounted so removable. In the embodiment shown, the longer mixing arms 7a each comprise two connecting arms 11a, 11a ', while only one

  link arm 1b is provided for each shorter mixing arm 7b.

  A drive motor 12 is installed below the bottom 4 of the annular tank mixer, a motor which rotates a hollow drive shaft 14 via a transmission 13 (see FIG. 2). The upper end of the drive shaft 14 is rigidly assembled to a horizontal carrier plate 15 on which is fixed, for example bolted, the bottom 5a of the rotor 5. When the drive motor 12 rotates, the rotor 5 sets in rotation, with the mixing arms 7 fixed on it as well as with the tools

  mixers 8, in the direction indicated by the arrow 16 in FIG. 1.

  The hollow drive shaft 14 is traversed coaxially by a stationary shaft 17, therefore non-rotary, at the upper end of which is

  rigidly mounted a toothed wheel 18.

  The cylindrical wall 5b of the rotor 5 carries (see FIG. 1) a console 19 on which a cyclone 20 with replaceable tools is mounted for rotation. Cyclone 20 is driven by means of an endless belt 21, which passes over a first belt pulley 22, coaxial with the tools of cyclone 20, and over a second belt pulley 23, mounted on the casing in the vicinity of the wheel toothed 18. The belt pulley 23 is itself rigidly assembled with a coaxial toothed wheel 24, which meshes with the stationary toothed wheel 18. The arrangement is therefore such that, during a rotation of the rotor 5, the toothed wheel 24 of the cyclone drive rolls on the central stationary toothed wheel 18 and then rotates the second belt pulley 23. This rotation is transmitted via the belt 21 on the first belt pulley 22, and therefore on the tools of cyclone 20. By the appropriate choice of sizes of the two belt pulleys 22 and 23, it is possible to fix in a simple manner the speed of rotation of cyclone 20. There is therefore no need for a

  separate drive for cyclone 20.

  The following explanations are now concerned with the configuration of the mixing tools 8, which provides a mixing action.

particularly satisfactory.

  As shown in FIG. 1, the external mixing tools 8a on the longer mixing arms 7a are inclined, with respect to the radial direction, so that they push the mixed product radially inwards. In addition, as shown schematically in Figure 3, the mixing tools 8a have an angle a relative to the vertical. This angle is between 20 and 45 and is adapted to the dimensioning of the mixing tool 8a as well as to the angular inclination of this tool relative to the

  radial direction, in a manner which will be detailed later.

  As shown in particular in FIG. 1, the exterior mixer tools 8a have larger dimensions than the interior mixer tools 8b in their projection on the radial direction. The projection of the external mixing tools 8a on the radial direction covers, in the example shown, more than half the width of the mixing chamber 1. The projection on the radial direction of the mixing tools 8b located radially to the interior is slightly larger than the radial slot than

  leaves the external mixing blade 8a free towards the internal wall of tank 3.

  This gives a slight overlap of the radial projections of the tools

  exterior and interior mixers 8a, 8b.

  The interior mixing tools 8b on the shorter mixing arms 7b are angularly inclined, with respect to the radial direction, so that they direct the mixed product from the inside to the outside. But they too are tilted at a given angle to the vertical, like the

shows figure 3.

  The angular distance between the external mixing tool 8a and the internal mixing tool 8b of the respective pair is chosen such that the flow of mixed product, which is directed radially inwards by the external external mixing tool 8a in the direction of movement, arrives on the interior mixing tool 8b, then is again directed outward by the latter. Unlike known mixers with an annular tank, it therefore takes place in a pair, between the external mixing tools 8a and the internal mixing tools 8b, a correlated movement of the mixed product which

  improves the mixing efficiency.

  The inclined position of the mixing tools 8a and 8b relative to the vertical (already claimed above with reference to FIG. 3) superimposes a vertical movement on the radial movement of the mixed product. In particular, the external mixing blades 8a are, due to this inclined position, overflowed by the mixed product which moves upwards on the front front face of the mixing tool 8a. The fact that the lateral outflow of the mixed product from the mixing tools 8a, 8b is accompanied by a certain resistance because of the relatively large dimensions of these tools, allows this overflow of the mixing tools 8a, 8b in a vertical direction at

  against the action of gravity.

  With the arrangement and configuration shown of the mixing tools 8a, 8b, a flow facies of the mixed product is thus obtained which has interlocking components both in the radial direction and in the vertical direction. This three-dimensional interlocking guidance of the movement of the mixed product is reproduced for each pair of mixing tools 8a, 8b during a complete revolution of the rotor 5. The homogenization of the mixed product which is thus obtained is further reinforced by cyclone 20, which develops its action in the space between opposite pairs of tools

mixers 8a, 8b.

  The mixing arms 7a, 7b are provided with a rotation stop not expressly shown in the drawing, which ensures that the lower edge of the mixing tools 8 is not less than a determined minimum distance a from the bottom 4 of the chamber mixing (see Figure 3), this distance can be for example equal to 3 mm. If a mixing tool 8 encounters an obstacle during its movement, for example larger components of the mixed product, it can avoid this obstacle from above by the fact that the bearing shafts 9 of the corresponding mixing arm 7 rotate around their longitudinal axis in the associated bearings 10. This can be done against the action of a spring; in many cases, however, due to the inclination of the mixing tools 8 of the angle a (FIG. 3) relative to the vertical, it is possible to dispense with a particular elastic return device, since this inclined position produced on the mixing tool 8, in cooperation with the mixed product moving upwards, a reaction force directed downwards. The mixing tools 8 can be configured in many ways within the framework of the basic principles defined above. Some exemplary embodiments are shown in FIGS. 4 to 8 for the external mixer tools 8a. However, insofar as nothing else follows from their particular function, the construction principles represented here and described below can also be used, by analogy, for tools

interior mixers 8b.

  In FIG. 4, the same numerical references have been used for the elements which are already represented in FIGS. 1 and 2, increased by 100. The corresponding elements in FIGS. 5 to 8 have numerical references which are differentiated each time from 100

  of the reference of the figure of number immediately lower.

  FIG. 4 represents a first embodiment of an external mixer tool 108a. The outer wall of the tank 102 and the bottom 104 of the mixing chamber are partially shown, as are the link arms 111 a which lead to the bearing shafts, which are no longer shown, of the

associated mixing arm.

  The mixing tool 108a is distinguished first by the fact that it is composed of several individual segments (three in the case shown) 108al, 108all and 108a111. The segment 108al, located radially inward, is connected to the link arm 111 a 'and can perform an upward movement independently of the segments 108all and 108a111, located further out. From the construction point of view, this can be made possible by the fact that, for example, the internal connecting arm 11a 'is connected to a hollow support shaft which coaxially surrounds a second, internal support shaft connected to the support arm external link 111a. The two bearing shafts can thus be pivoted about their longitudinal axis independently, one

the other.

  The two segments 108all and 108a111i, located radially further out, are mutually connected and guided jointly by the outer link arm 111a, so that they can perform, optionally also

  together, an upward directed avoidance movement.

  A second characteristic of the mixing tool 108a of FIG. 4 consists in that it has a greater height in the radially outer region, which is close to the outer wall of the tank 102, than in the radially inner region. In this outer region, in fact, the vertical overflow of the mixing tool 108a is neither necessary nor desired; the mixed product must on the contrary, in this region of the mixing tool 108a, be directed exclusively radially from the outside to the inside. This is why the radially outermost segment 108a111i of the mixing tool 108a can also renounce, in the vicinity of the outer wall of tank 102, the angle of inclination a relative to the vertical (see

figure 3).

  The example of embodiment of the external mixer tool 208a which is represented in FIG. 5 corresponds, unless otherwise indicated below, to the example of embodiment of FIG. 4. It differs from this latter essentially by the fact that the height of the radially inner segments 208al and 208all increases with the decrease in the radial distance from the center of the annular tray mixer. This means that the vertical overflow of the mixing tool 208a decreases while the distance from the center of the annular tray mixer is reduced. The radially innermost segment 208al has from the front, therefore seen in the direction of the incoming flow, a convex curvature which is followed by a concave curvature in the region near the bottom. The described configuration of the mixing tool 208a produces an overflow facies according to which the partial flow, which projects vertically from the mixing tool 208a in its lowest regions, is directed "under the

  covered "of segment 208a11, located radially inward.

  The embodiment of the mixing tool 308a which is shown in FIG. 6 shows the main construction characteristics of the mixing tool 208a of FIG. 5, with certain variants: thus, for the mixing tool 308a also, the outermost segment 308a111 is oriented practically vertically on its outer edge, which is close to the external wall of tank 302, and is highest in the vicinity of the external wall of tank 302. Unlike the embodiments of the Figures 4 and 5, this outermost segment 308a1li1 is provided with a wear protection 330 integrally formed, which is forged backwards around the lateral face of the link arm 31a and thus protects this arm from 'wear. Similarly, the inner link arm 311a 'is surrounded by a wear protection 331 which is formed on the segment 308al, located

  radially innermost, of the mixing tool 308a.

  In the example of embodiment of a mixing tool 408a which is represented in FIG. 7, respective additional auxiliary blades 432, 433 are attached to the link arms 41a 'and 411 in a plane situated above the main segments 408al, 408all and 408a111i, which are essentially configured in accordance with Figure 4. These auxiliary blades 432, 433 are inclined relative to the vertical so that they direct the mixed product down, while their orientation angular with respect to the radial direction is such that, like the lower segments 408al, 408a11, 408a111, they direct the mixed product radially from the outside to the inside. Finally, in the exemplary embodiment of the mixing tool 508a which is represented in FIG. 8, the individual segments 508al, 508all and 508a111i are no longer arranged while being directly contiguous, but on the contrary have a slight mutual distance. However, the remaining slit present between the individual segments 508al, 508all and 508a111 is so small that a certain flow of material can certainly take place through these slits, respectively "under cover" of the neighboring segment radially inside, but that the overall unitary function of this external mixing tool 508a is not modified, a function which consists in directing the mixed product, over a relatively large radial distance, in a controlled manner inwards so that a coordinated interaction can take place, in the way

  described above, with the associated mixing tool located radially inside.

  As regards the vertical overflow, the segments 508al, 508all and 508a111 of the external mixer tool 508 shown in FIG. 8 are not different from the segments 108al, 108all and 108a111 of the example of

realization of figure 4.

  The individual segments 508al, 508all and 508a111, physically separated from each other, of the mixing tool 508a of FIG. 8 must of course be each carried by their own link arm 51 la, 51 la 'and 51 la ", these arms being connected, in a manner analogous to what has been described above for the embodiment of FIG. 4, to load-bearing shafts which rotate about their longitudinal axis independently of one another and guided coaxially one inside the other. The individual segments 508al, 508all and 508a111 can

  thus accomplish an independent avoidance movement.

  The radially outermost segment 508a111i of the mixing tool 508a of FIG. 8 carries, at its lower front vertex in the direction of movement, a part in a replaceable stirrup 534 made of a material particularly resistant to wear, which evacuates by scraping the edge between the bottom

  504 and the outside wall of tank 502 of the annular tank mixer.

  In all the exemplary embodiments which are represented in FIGS. 4 to 8, the link arms 111 to 511 have the form of plates on the narrow side from which the mixed product flows. The wear of the link arms 111 to 511 is thus reduced, and the resistance to displacement produced by the link arms.

link 111 to 511 minimized.

  In the annular tank mixer shown in FIG. 2 and described above, the support shafts 9 of the mixer arms 7 extend horizontally. It is the simplest construction to carry out. If particularly small slots are required between the tank wall and the neighboring mixing tool, it is possible to use a configuration of the annular tank mixer as shown in FIGS. 9 and 10. These figures correspond, unless otherwise indicated below. after, in Figure 2 of the first embodiment. The section planes of Figures 9 to 10 are angularly rotated relative to each other so that we can see in Figure 9 the longer mixing arm 607a, and in Figure 10 the shorter mixing arm 607b, with a pair of arms

mixers 607.

  In this embodiment, as clearly shown in FIG. 9, the bearing 610a of the carrier shaft 609a forming part of the longer mixing arm 607a is inclined relative to the horizontal so that the carrier shaft 609a is more higher at its radially outer end than at its radially inner end. A precise analysis of the geometric relationships reveals that with this angular orientation of the carrier shaft 609a, the mixer tool 608a fixed on it can achieve a greater avoidance movement, without collision with the outer wall of tank 602, even if , in the shown working position, the slot between the external mixing tool 608a

  and the outer wall of tank 602 is very small.

  For the same reasons, in the shorter mixing arm 607b shown in FIG. 10, the carrier shaft 609b is inclined relative to the horizontal, in its bearing 610b, so that its end radially

  inner is higher than its radially outer end.

Claims (28)

  1.- Annular tank mixer, with a) a casing, in which is configured an annular mixing chamber delimited by an external tank wall, an internal tank wall and a bottom, b) a rotary rotor on which is fixed, by means of a plurality of mixing arms extending in the mixing chamber, a plurality of mixing tools arranged at different radial distances from the center of rotation, the external mixing tools being angularly inclined, with respect to the radial direction, so that they give the mixed product a movement component radially inwards, and the interior mixing tools being angularly inclined, with respect to the radial direction, so that they give the mixed product a movement component radially outwards, characterized in that c) the mixing tools (8; 108; 208; 308; 408; 508; 608) are respectively provided in pairs, each comprising an external mixing tool (8a; 108a; 208a; 308a; 408a; 508a; 608a) next to the external wall of the tank (2; 102; 202; 302; 402; 502; 602) and an internal mixing tool (8b; 608b) close to the internal wall of the tank (3; 603), d) at the at least one of the mixing tools (8; 108; 208; 308; 408; 508; 608) of each pair has, in its projection on the radial direction, an extent at least equal to 40% of the width of the mixing chamber ( 1; 601), e) the angular distance between the mixing tools (8; 108; 208; 308; 408; 508; 608) of each successive pair in the direction of movement is chosen so that the mixing tool (8a; 108a; 208a; 308a; 408a; 508a; 608a) anterior in the direction of movement directs the flow of mixed product on the mixing tool (8b; 608b) posterior in the direction of travel.   2.-annular tank mixer according to claim 1, characterized in that the external mixer tool (8a; 108a; 208a; 308a; 408a; 508a; 608a) has, in its projection on the radial direction, a   greater extent than the internal mixer tool (8b; 608b).   3.- Annular tank mixer according to claim 1 or 2, characterized in that the sum of the expanses, projected on the radial direction, of the two mixing tools (8; 108; 208; 308; 408; 508; 608) of each pair is approximately equal to the width of the chamber mixture (1; 601).   4.-Annular tank mixer according to any one of   previous claims, characterized in that each mixing tool (8;   108; 208; 308; 408; 508) is inclined relative to the vertical by an angle between 20 and 45, so as to facilitate its overflow by the mixed product. 5.- annular tank mixer according to claim 4,   characterized in that the angle is between 30 and 35.   6.- Annular tank mixer according to any one of   previous claims, characterized in that each mixing tool   outside (8a; 108a; 208a; 308a; 408a; 508a) has, in the region adjacent to the outer wall of the tank (102; 202; 302; 402; 502), a more   greater height than in regions located radially further inland.   7.- Annular tank mixer according to any one of   previous claims, characterized in that each mixing tool   outside (108a; 208a; 308a; 408a; 508a) extends vertically on its edge adjacent to the outer wall of the tank (102; 202; 302; 402; 502), while it is inclined at a certain angle by vertical to a region radially more inside.   8.- Annular tank mixer according to any one of   previous claims, characterized in that the height of the tools   external mixers (208a; 308a) present, at a given distance from the external wall of the tank (202, 302), a minimum from which it increases in both directions.   9.- Annular tank mixer according to any one of   previous claims, characterized in that at least one protection   against wear (330, 331) is formed on the mixing tools (308), protection which surrounds the region (311 la) of the mixing arm which extends into the product   mixed, at least on the side where the mixed product flows.   10.- Annular tank mixer according to any one of   previous claims, characterized in that at least some of the   mixing tools (108; 208; 308; 408; 508) is composed of segments   (1081, Il, 111; 2081, II, 1Il; 3081, II, 111; 4081, II, 111; 5081, II, 11).   11.-annular tank mixer according to claim 10, characterized in that the segments (1081, II, III; 2081, 11, 111; 3081, 11, III1; 4081,   He, 111; 5081, II, III) are at least partially independent parts.   12.- annular tank mixer according to claim 11, characterized in that the segments (1081, II, 111; 2081, II, III; 3081, II, III1; 4081, II, III) are, in their normal position work, contiguous by lateral edges. 13. An annular tank mixer according to claim 11, characterized in that slots remain present between the lateral edges of the segments (508 1, II, III), slots through which partial flows of mixed product can pass, but which are narrow enough that   the entire mixing tool retains its overall unitary function.   14.- Annular tank mixer according to any one of   previous claims, characterized in that at least one auxiliary blade   (432, 433) is mounted vertically at a distance above the mixing tool (408) on the region (41 la), sinking into the mixed product, of at least one mixing arm, blade which is inclined by relation to the vertical so   that it pushes the mixed product down.   15.- Annular tank mixer according to any one of   previous claims, characterized in that at least one mixing tool   (508) is provided, at an apex, with a stirrup piece (534) of material with high wear resistance, which evacuates the edge between the bottom (504) and the wall of neighboring tank (502).   16.- Annular tank mixer according to any one of   previous claims, characterized in that each mixing arm (7;   607) comprises: a) at least one carrier shaft (9; 609) rotatably mounted on the rotor (5; 605), b) at least one connecting arm (11; 611) fixed on the carrier shaft (9; 609), arm which extends into the mixing chamber (1; 601) and at the end of which is attached a mixing tool (8; 608).   17.- Annular tank mixer according to claim 16,   characterized in that the carrier shaft (9) extends substantially horizontally.   18.- Annular tank mixer according to claim 16, characterized in that the carrier shaft (609a) of each longer mixing arm (607a) is inclined, relative to the horizontal, so that it is more higher at its radially outer end than at its radially inner end. 19.- Annular tank mixer according to claim 17 or 18, characterized in that the carrier shaft (609b) of each shorter mixing arm (607b) is inclined, relative to the horizontal, so that it is higher at its radially inner end than at its radially outer end. 20.- Ring tank mixer according to any one of   Claims 16 to 19, characterized in that the bearing (10) for the carrier shaft   (9) has a rotation stop which guarantees that a minimum distance (a) remains between the mixing tool (8) and the bottom (4) of the mixture (1).   21.- Annular tank mixer according to any one of   Claims 16 to 20, characterized in that a spring device is provided   which presses the carrier shaft (9) in the direction of the rotation stop.   22.- Annular tank mixer according to any one of   Claims 16 to 21, characterized in that each carrier shaft (9)   has an angle other than 90 with the tangential plane which passes through its attachment point on the rotor (5).   23.- Annular tank mixer according to any one of   Claims 11 to 13, characterized in that a separate mixing arm (7) is   associated with each independent segment (1081, II, III; 2081, II, III; 3081, II, III;   4081, II, III; 5081, II, III) of a mixing tool (108; 208; 308; 408; 508).   24.- Annular tank mixer according to claim 23, characterized in that a separate carrier shaft, mounted for rotation on the rotor, is associated with each independent segment of a mixing tool, all the carrier shafts being arranged coaxially and at minus the bearing tree (s)   exteriors being made hollow.   25.- annular tank mixer according to claim 24, characterized in that a separate spring device is associated with each of the coaxial bearing shafts, device which presses the bearing shaft against a clean rotation stop.   26.- Ring tank mixer according to any one of   Claims 16 to 25, characterized in that each link arm (11;   111; 211; 311; 411; 511) is a plate-shaped element, on the side   narrow from which the mixed product can flow.   27.- Mixer with annular tank according to any one of   previous claims, characterized in that at least one cyclone (20) is   fixed on the rotor (5) between two neighboring pairs of mixing arms (7a, 7b). 28.-Annular tank mixer according to claim 27, characterized in that the drive for the cyclone (20) comprises: a) a toothed wheel (18) coaxial with the axis of rotation of the rotor (5), but stationary , b) a toothed wheel (24) mounted on the rotor (5), meshing with the stationary toothed wheel (18) and assembled in rotation solidarity to a first coaxial belt pulley (23), c) a second belt pulley (22), rotatable together with the tools of the cyclone, d) an endless drive element (21) connecting the two pulleys belt (22, 23).