EP1123731B1 - Mixing apparatus - Google Patents

Abstract

An agitator assembly, in particular for mixing, granulating and drying solid matter, includes a vessel; and an agitator received in the vessel and having at least one sweep blade, with the sweep blade ascending from an inner zone of the vessel to an outer zone thereof at an angle of inclination ranging from about 15° to 60° with respect to the horizontal.

Description

The invention relates to a stirring device, in particular for mixing, Granulating and drying of solids, with at least one stirring element with stirring blades, which has, for example, two stirring blades, which are driven by a motor Wave are connected.

The stirring device can also be used to heat and cool solids used, but also to carry out chemical reactions, for evaporation of solvents, or for evaporation or Cooling crystallization.

US 4,941,750 discloses a stirrer having three on a driven shaft attached stirring blades at an angle in a range of 30 ° to 70 ° are inclined upwards from the inside to the outside with respect to the horizontal. The Stirring leaves have the shape of half-crescent-shaped, in a Direction of rotation of the stirrer with respect to the radial direction backwards are curved. The width of the stirring blades decreases from the inside to the outside.

US 4,392,361 discloses an apparatus for preparing fiscreme, comprising a base part with a substantially cylindrical mixing chamber, a projecting from below into the mixing chamber driven shaft and two different agitator blades attached to the shaft. The one Ruhrblatt is a substantially planar multifunctional mixing and stirring blade, in one embodiment, both with respect to a rotational axis of the shaft of bottom inclined upwards at an angle as well as in relation to a tangential direction in the direction of rotation forward at an angle is arranged inclined outside, and in another embodiment itself tangential with respect to the substantially constant width shaft extends outwards and in the direction of rotation forward similar to an airfoil is inclined downwards, with its lower edge just above the Bottom of the mixing chamber. The other stirring blade is a Sctra leaf with the Task, mix from the outer wall of the mixing chamber away inwards too transport. The scraper blade has an inner area that extends in the substantially radially outwardly with a substantially constant width extends, and an outer cockroach area, in the one Embodiment with respect to the inner area from the inside to the outside curved upward and twisted in the direction of rotation towards the front and the in the other embodiment in the direction of rotation angled forward and is inclined.

US 4,722,608 discloses an agitator having three on a driven one Shaft in the direction of rotation equidistantly attached agitator blades. The stirring blades extend substantially in a horizontal plane radially from the inside to the outside, with the width over a substantial part to the outside decreases. The stirring blades are inclined downwards in the direction of rotation and in twisted, the torsion angle decreases from the inside to the outside at their outer ends, the stirring blades are vertical (parallel to the shaft) extending side leaves, which are either relatively thin in the radial direction and circular arc-shaped or at a clearance angle to the in essential cylindrical wall of the stirred tank, in the direction of rotation backwards tilted inward from the wall, are arranged

DE 675 302 discloses a stirring device with a closed one axialsymmetnschen stirred tank, in the axially from above a driven Wave immerses, which has at its lower end beating arms, extending from inside down radially outwards above essentially flat and with a constant Width extend. Furthermore, dive into the stirred tank from above eccentric arranged, height-adjustable and rotating driven rods. At every Rod are attached to essentially flat, elongated baffles, with the on the one pole attached Strombrecher another Inclination angles with respect to the horizontal than those at the other Rod attached stream breaker.

US 5,090,815 discloses a device for mixing flowable material with a height adjustable by means of hydraulically driven motors Rührgefaß with a cup-shaped convex bottom portion and a substantially cylindrical upper area, one from above axially in the Ruhrgefaß submerged shaft, at the lower end of three in the circumferential direction Equidistantly mounted stirring arms protrude outward. Every Ruhr arm consists of a short inner area that extends essentially radially extends outside, and one the essential part of the Ruhr arm constituting tangentially shaft - aligned region which is in the Comparison to the inner region in the direction of rotation with respect to the radial direction bent backwards. The shape of the lower edge of the stirring arms is attached to the Shape of the inner surface of the bottom portion of the mixing vessel adapted At their outer ends, the stirring arms point vertically upwards (parallel to the Wave) kinked areas. In the upper part of the mixing vessel can an additional stirring device with a mounted above the mixing vessel, driven shaft with mixing or stirring blades at its lower end

Finally, DE 2 012 788 discloses a stirrer for melting in the Form of blocks delivered products, such as bituminous or similar substances. The agitator includes a container with an in essential cylindrical, merging into a conical bottom Heating mantle, a lid with a filler neck for the blocks and a Drive and a storage for a projecting down into the container Agitator shaft. In a lower portion of the stirring shaft stirring arms are normal Type, in particular from the bottom inside upwards outward in a radial Level protruding paddles, and in the upper part of a plate-like stirring provided with ribs provided thereon. The delivered blocks will be placed on the plate-like stirring, the ribs to the side Limiting and taking the blocks serve. If the plate-like Ruhr part in Rotation is offset, the blocks slip on it by the centrifugal force radially to the outside and against the heating jacket, leaving them in a thin Melted interface on its outside

Object of the present invention is, in addition to achieving a Mischgüte and a high internal heat transfer, a dead space Mixing also in a lower area of a stirred tank to allow.

The object is achieved by a stirring device, in particular for Mixing, granulating and drying of solids in a stirred tank, with at least one stirrer with stirring blades, which has, for example, two stirring blades, which with a motor drivable shaft are connected and the particular planar trained stirring blades at an angle α, in one area From about 15 ° to about 60 °, from the inside outwards inclined to the Horizontal are arranged at least one of the stirring blades at its inner end equipped with a Bodenräumer forming bottom sheet.

The stirring element preferably has two stirring blades.

Preferably, the stirring blades are flat.

Preferably, the bottom sheet has the largest and at its upper end its lower end the smallest width.

Advantageously, the bottom blade is helically twisted and in an angle δ to the horizontal employed, the angle of attack δ of increases from top to bottom and is in the range of 5 ° to about 55 °.

Conveniently, the inner and outer peripheral edges of each stirring blade have an elliptical shape.

Advantageously, each agitating blade has the smallest width at its inner end and the largest width at its outer end.

Preferably, each stirring blade is at its upper, outer end with a in particular flat side sheet equipped with the side sheets under an inclination angle γ of about 1 ° to about 30 ° to the vertical employed are. Furthermore, the side panels have expediently a clearance angle β from about 1 ° to about 30 ° to the inner wall of the Rührbehalters.

Preferably, the leading edge or the leading edge has each Seitenblattes a substantially constant distance from the cylindrical Inner wall of the stirred tank, wherein the distance expediently about 5 to 10 mm.

At least this leading edge of each page sheet is more advantageous wise an elliptical shape.

In a further embodiment of the invention can above the Rührblatter a preferably flat baffles be incorporated, the lower edge in an angle ∈ to the horizontal, which ranges from about 15 ° to 60 °.

Conveniently, the baffle is at an angle ψ , which is in a range of about 0 ° to about 75 °, employed to a radial, which passes through the center axis of the agitator shaft and through the center axis of the baffle.

According to a further embodiment of the invention, above the Stirring blades at least one motor driven chopper be installed who carries at the end of a plurality of knives. The peripheral speed the chopper is expediently more than 15 m / sec.

Preferably, the stirring container consists of an upper cylindrical part and an adjoining lower conical bottom part, wherein its cone angle is in the range of about 60 ° to about 120 °, and in particular substantially 90 °.

Advantageously, the stirring arms are substantially in the conical part of the Stirred container arranged.

The ratio of the heights of the tapered part to the cylindrical part of the Stirred vessel is advantageously in the range of about 1: 1 to about 2: 1.

Fig. 1

schematisch eine Ansicht der erfindungsgemäßen Rührvorrichtung zeigt,

Fig. 2

eine Draufsicht auf die Rührvorrichtung nach Figur 1 zeigt,

Fig. 3 und 4

zeigen entsprechend eine Ansicht und eine Draufsicht auf eine weitere Ausführungsform der erfindungsgemäßen Rührvorrichtung,

Fig. 5

zeigt schematisch noch eine Ausführungsform der erfindungsgemäßen Rührvorrichtung, und

Fig. 6

zeigt eine Einzelheit der Anordnung eines Rührblattes mit dem zugehörigen Seitenblatt.

For example, embodiments of the invention will be explained below with reference to the drawings, in which

Fig. 1

schematically shows a view of the stirring device according to the invention,

Fig. 2

a top view of the stirring device of Figure 1 shows

3 and 4

show correspondingly a view and a top view of a further embodiment of the stirring device according to the invention,

Fig. 5

schematically shows an embodiment of the stirring device according to the invention, and

Fig. 6

shows a detail of the arrangement of a stirring blade with the associated side sheet.

Figure 1 shows schematically a stirring device 10 with a dash-dotted line indicated stirred tank 12, which consists of an upper cylindrical part 14 and adjoining this lower conical bottom Part 16 is formed.

The cylindrical part 14 is closed at the top by a curved lid 18, while at the lower end of the conical bottom part 16, an outlet 20th is trained.

A drive shaft 22 extends from above through the lid 18th down into the stirred tank 12 and on the shaft 22 are by means of a respective spar 24 two stirring blades 26 attached, which substantially accommodated in the conical bottom part 16 of the stirred tank 12 are and from the bottom down to the outside at an angle α to the horizontal extending in the range of about 15 ° to about 60 °.

The cone angle of the bottom part 16 of the stirred tank 12 is located in one Range of about 60 ° to about 120 ° and it is preferably substantially 90 °.

The term "vertical" used in the specification refers to the Direction of the central axis of the shaft 22 and the term "horizontal" refers in all directions which are perpendicular to the central axis of the shaft 22.

At least one of the stirring blades 26 closes at its lower end a Bodenräumer forming bottom sheet 28, the upper end of the 48th fixed to the inner, lower end 44 of the respective stirring blade 26th connected is. (Figure 3)

The bottom sheet 28, the lower end 50 into the outlet 20 into it extends, is helically wound and at an angle δ to Turned level down or turned to horizontal. At least in the vicinity of the other end 50, the angle 5 decreases from above down to and within the range of about 5 ° to about 55 °.

The geometry of the stirring blades 26 is performed by an oblique cut produces a cone so that the inner peripheral edge 40 and the outer Peripheral edge 42 of each stirring blade 26 have an elliptical shape and the Blades 26 remain even.

The width of the stirring blades 26 increases from the inside to the outside and each Stirring blade 26 has at its inner end 44, the smallest width and at its outer end 46, the largest width.

The width of the bottom sheet 28, however, decreases from top to bottom and it therefore has its greatest width at its upper end 48 and its smallest width at its lower end 50.

With each stirring blade 26 is at its upper, outer end 46, a side sheet 30 firmly connected. The page leaves are flat and their geometry becomes produced by an oblique section through a cylinder, wherein at least the leading edge or leading edge 52 of the side panels 30 has an elliptical shape.

The formed opposite the stirring blades 26 bent upwards Side leaves 30 are at an inclination angle γ to the vertical outward adjusted in the range of about 1 ° to about 30 °.

With respect to the inner wall of the stirred tank 12, the side sheets 30 a clearance angle β of about 1 ° to about 30 °, as Figure 4 shows.

This angle β is determined as follows.

Between the midpoint M of the shaft 22 and the intersection P of Side sheet 30 with the stirring blade 26 is pulled a line 64. The vertical 66 on this line 64 at the point P is the reference line for the angle β, extending between this perpendicular 66 and the intersection 68 between the stirring blade 26 and the side panel 30 extends.

(The intersection P denotes that in the direction of rotation D of the stirring device front end of section line 68.)

As particularly shown in Figure 6, the leading edge 52 has each side sheet 30 a substantially constant distance 58 of about 5mm to 10mm to the cylindrical inner wall 56 of the stirred tank 12th

Figures 3 and 4 show embodiments in which auxiliary devices in Shape of a baffle 32 and / or a chopper 34 from above in the stirring container 12 are installed.

It may, as I said, a baffle 32 or a chopper 34 or it If necessary, both devices can also be used.

The baffle 32, preferably in the form of a flat plate is vertically installed from above into the stirred tank 12 and has, as illustrated, approximately V-shaped configuration, wherein its lower edge 60 a Angle ∈ forms to the horizontal, which ranges from about 15 ° to about 60 ° lies.

The edge 60 extends from the bottom inside outwards.

As FIG. 4 shows, the baffle 32 is at an angle in the direction of rotation D. ψ to a radial 62, which ranges from about 0 ° to about 75 ° is located.

The radial 62 extends through the central axis of the shaft 22 and through the Central axis of the baffle 32. (Figure 4)

The chopper 34 is also from above through the lid 18 in the Rührbehälter 12 introduced and dives like the baffles 32 in the mix a, as Figure 3 shows.

The chopper 34 consists of a motor-driven shaft 36, the its lower end a plurality of knives 38 or other suitable Carries tools through which any clumps in the stirred material or can be resolved.

The drive (not shown) for the chopper 34 is mounted on the lid 18 and the shaft 36 extends eccentrically between the shaft 22 and the Stirring blades 26.

The peripheral speed of the chopper 34 is preferably above 15 m / sec, whereby locally very high shear forces introduced into the product can be. As a result, especially heavy lumps and Parts of tubers in the product. Instead of the knives 38, as above Also, other tools may be used depending on the Product properties to produce more or less shear in the product.

The baffle 32 reduces the rotational movement in the stirring, also It carries larger lumps, possibly during drying The agitators are where they are parted.

As the figures 1 and 3 show, the spars 24 at the lower end of Shaft 22 and in the lower half of the conical bottom part 16, as much free space for installations as the baffle 32nd or the chopper 34.

As Figure 5 shows, but in addition to the pair of bars 24 and above the latter another pair of bars 54 for holding the stirring blades 26 at the drive shaft 22 may be provided in case of need.

The stirring device according to the invention operates as follows:

Upon rotation of the stirring blades 26 in the direction of rotation D, the product is along the Wall of the stirred tank obliquely and then conveyed axially upwards and then in the area of the product surface through the side panels 30 to the center transported. In the middle range, the product then becomes mass flow pulled down, creating a large-scale, essentially dead space-free Mixing movement occurs, the short mixing times and high heat transfer guaranteed. The peripheral speed is so high that easily disintegrating lumps and tubers by the shear stresses, which are generated by the stirring blades 26, are digested. Moderate decaying lumps can be formed by incorporating one or more Baffles 32 are decomposed while heavy decaying lumps through the eccentric built-in chopper 34 are destroyed.

The Bodenräumer forming bottom sheet 28 allows a dead space Mixing in the lower part of the conical bottom part 16 above the not shown exhaust valves. The above-described descending Angle of attack δ of the bottom blade 28 serves a good mixing effect to maintain, as these at the same setting angle would decrease because the peripheral speed on the bottom blade 28 for Outlet valve is getting smaller and smaller. The increasing angle of attack δ compensates for this effect and ensures a dead space free mixing of the entire container.

The above-mentioned close wall distance of the side leaves 30 to the inner wall the stirring container 12 prevents at least substantially wall coverings and crusting, thus ensuring good heat transfer coefficients.

The stirring device according to the invention is therefore not only suitable for pourable products, but also for doughy and when drying tubers forming products, such as those in the pharmaceutical Industry occur.

The stirring device according to the invention enables a high mixing quality through complete product revolution. It allows a high internal heat transfer and a uniform temperature profile and thus a great surface renewal and a good removal without recondensation in the cooler product. The high heat transfer surface leads to shorter drying times and cooling times. Enable the stirring blades especially in connection with baffles and choppers a good Crushing and a quick and easy disintegration of lumps and tubers.

It is thus also possible to disperse agglomerates or to produce granules also doughy or waxy masses can be circulated. Due to the higher blade pitch becomes a good quantitative emptying reaches and it can deposits and crusting largely be avoided. The conical bottom part allows a good drainage of the dry product.

Since the drive shaft 22 is installed flying from above, are no bearings or seals in the product area required.

Claims (21)

1. Mixing device (10), in particular for mixing, granulating and drying solid materials in a mixing tank (12), having at least one mixing element with blades, having for example two blades (26) which are connected to a motor-drivable shaft (22) and the blades of substantially flat construction are arranged slanting upwards from inside outwards at an angle α which lies in the range from about 15° to about 60° to the horizontal, characterised in that at least one of the blades (26) has at its inner end (44) a bottom blade (28) which forms a bottom scraper.
2. Mixing device according to Claim 1, characterised in that the bottom scraper (28) is widest at its upper end (48) and least wide at its lower end (50).
3. Mixing device according to Claim 1 or 2, characterised in that the bottom scraper (28) has a helical twist.
4. Mixing device according to one of Claims 1 to 3, characterised in that the bottom scraper (28) is set inclined downward at an angle δ to the horizontal and that the angle of incidence δ lies in the range from about 5° to about 55°.
5. Mixing device according to one of the foregoing Claims, characterised in that the inner (40) and outer edges (42) of each blade (26) are elliptical in shape.
6. Mixing device according to one of the foregoing Claims, characterised in that each blade (26) is least wide at its inner end (44) and widest at its outer end (46).
7. Mixing device according to one of the foregoing Claims, characterised in that the mixing element has two blade¹ (26).
8. Mixing device according to one of the foregoing Claims, characterised in that the blades (26) are of flat construction.
9. Mixing device according to one of the foregoing Claims, characterised in that each blade (26) is furnished at its upper outer end (46) with a side blade (30), in particular a flat one, and the side blades are set at an outward inclination angle γ of about 1° to about 30° to the vertical.
10. Mixing device according to Claim 9, characterised in that the side blades (30) are set at a clearance angle β of about 1° to about 30° to the wall of the mixing tank (12).
11. Mixing device according to Claim 9 or 10, characterised in that the leading edge (52) of each side blade (30) has a substantially constant separation distance (58) from the cylindrical wall of the mixing tank (12).
12. Mixing device according to Claim 11, characterised in that the separation distance (58) is about 5 mm to 10 mm.
13. Mixing device according to Claim 11, characterised in that at least the leading edge (52) of each side blade (30) is elliptical in shape.
14. Mixing device according to one of the foregoing Claims, characterised in that above the blades (26) at least one baffle (32), in particular a flat one, is fitted whose lower edge (60) runs at an angle ε to the horizontal, this angle being in the range from about 15° to about 60°.
15. Mixing device according to Claim 14, characterised in that in the direction of rotation D the baffle (32) is set at an angle Ψ which lies in the range from about 0° to about 75° to a radial (62) passing through the centre axis of the shaft (22) and the centre axis of the baffle (32).
16. Mixing device according to one of the foregoing Claims, characterised in that above the blades (26) at least one motor-operable chopper (34) is incorporated which has at its end a plurality of cutting blades (38).
17. Mixing device according to Claim 16, characterised in that the circumferential speed of the chopper (34) When in operation is over 15 m/sec.
18. Mixing device according to one of the foregoing Claims, characterised in that the mixing tank (12) consists of an upper cylindrical section (14) and a lower tapering base section (16).
19. Mixing device according to Claim 18, characterised in that the angle of taper of the tapering base section (16) lies in the range from about 60° to 120°.
20. Mixing device according to Claim 18 or 19, characterised in that the ratio of the height of the tapering base section (16) to that of the cylindrical section (14) lies in the range from about 1:1 to about 2:1.
21. Mixing device according to one of Claims 18 to 20, characterised in that the blades (26) are fitted mainly in the tapering base section (16) of the mixing tank (12).

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