DEVICE FOR TREATING MATERIAL WITH A CONTAINER

Description

[0001] The invention relates to a device for treating material, comprising a container in which a stirrer rotatable about a central axis is arranged, and comprising a first deflection device arranged in the container above the stirrer in order to divert a material flow conveyed by the stirrer to the center of the container, wherein the stirrer has a coaxial axial body, the diameter of which in the region of the stirrer is at least a quarter of the diameter of the stirrer.

[0002] There are various types of stirrers, which are usually open at the top. The material flow is thus stirred in the stirrer vessel, and the material that is stirred upwards moves upwards until it is forced back down again by gravity.

[0003] Publications WO 2011 / 144196, WO 2012 / 041269, and WO 2013 / 135224 show material treatment devices with containers shaped so that the material flow conveyed by the agitator is diverted through an inner container wall above the agitator toward the center of the container. A central screw conveys the material from an upper region of the container to the agitator, from where the material flow travels radially outward, upward, and guided by the deflection device toward the center of the container.

[0004] It has been found that, particularly when treating coarse materials, lumps are formed which no longer dissolve or dissolve only poorly in the stirrer.

[0005] US Pat. No. 4,938,423 A shows a vessel with deflection devices arranged at the vessel's rim. This creates several smaller vortices within the vessel. However, this leads to increased energy input and dead zones between the vortices.

[0006] The invention is therefore based on the object of developing such devices in such a way that the formation of lumps is avoided.

[0007] This object is achieved by a device having the features of claim 1.

[0008] To utilize the stirrer in both its radially outer and inner regions, it has previously been proposed to arrange the stirrer's functional areas along a small-diameter axis. This allows the material to flow into the center of the stirrer and then from the radially inner regions to the radially outer regions of the stirrer.

[0009] In the radially inner areas of the agitator, the peripheral speed is relatively low, making it most likely that unwanted clumping will form. Even with feed spirals and a special design of the agitator arms, clumping is difficult to prevent.

[0010] It has been determined that a conveyor above the agitator to transport material to the agitator is unnecessary and can even be detrimental. Therefore, the container on the central axis does not have a conveyor to transport material to the agitator.

[0011] The invention is therefore based on the realization that the central region of the stirrer, in which the axis is located, is of secondary importance for the stirrer function due to the low acceleration present there and should therefore be designed as a coaxial axis body with an enlarged diameter. The coaxial axis body refers to a body formed by the axis itself, a cylinder arranged around the central axis, or another body designed to keep this central region free of material. This means that the material is only treated by the stirrer in an area spaced apart from the center of the stirrer, and the central area is inaccessible to the material, meaning that no clumping can occur there. In the radially outer region, however, the peripheral speed is so high that good circulation is achieved and there is therefore no risk of clumping.

[0012] In order to achieve particularly good circulation with low energy consumption, it is proposed that the container has a bottom below the stirrer and that a distance between the bottom and the deflection device is a maximum of half the maximum diameter of the container between the bottom and the deflection device.

[0013] It is advantageous if the distance between the central axis and the radially outer inner wall of the vessel in the area of ​​the agitator approximately corresponds to the distance between the bottom and the deflection device. "Approximately" here means a deviation of a maximum of 30% and preferably a maximum of 20% of the larger distance.

[0014] The floor can be designed as a continuous floor surface, as in a kneader, or as a perforated sheet, as in a processor.

[0015] The stirrer or stirrer arms should extend as far as possible into the radially outer regions of the vessel to avoid dead zones. Therefore, it is recommended that the stirrer diameter be at least 70%, preferably at least 80%, of the maximum diameter of the vessel in the stirrer area.

[0016] An advantageous embodiment provides that the stirrer has one or more arms that extend radially outward from the central axle body.

[0017] A particularly simple embodiment provides for the first deflection device to comprise a circular plate arranged in the container with a central, free passage. In a simple embodiment, this is a horizontal sheet with a central, free passage that allows the container to be fed with material.

[0018] The container can also be shaped so that the first deflection device is formed by a constriction on the container. The container thus has a smaller diameter in the area of ​​the deflection device than below the constriction, and preferably also a smaller diameter than above the constriction. This allows the area above the constriction to be used as a feed and buffer area, while the reaction area with the stirrer is located below the constriction.

[0019] In order to ensure sufficient inward deflection of the material by means of the first deflection device, on the one hand, and to be able to easily feed additional material centrally, on the other hand, it is proposed that the first deflection device have a central free passage with a diameter of at least 0.8 m. For example, the free passage can have a diameter of less than 80% or even less than 60% of the maximum container diameter.

[0020] When using the kneader, the water level should be at or above the diameter constriction. For example, if the diameter constriction is formed by a plate, the water surface should be at the same level as the plate or slightly above it. This calms the water surface and reduces energy loss through rippling.

[0021] The free diameter should allow solids to be fed into the lower section. This solids should fall into the lower section on its own, making a feed screw unnecessary.

[0022] In a device with two agitators arranged one above the other, the deflection device does not need to be made of a solid material, since one material stream can serve as a deflection device for the other. Therefore, it is proposed that the first deflection device be formed by a material stream conveyed downwards toward the center of the container by a further agitator arranged above the first agitator.

[0023] A feed chamber formed as part of the vessel above the deflection device is suitable as a buffer and to increase the pressure in the agitator area. This feed chamber can also be another vessel section, a collar, or a cylindrical vessel section.

[0024] Especially when the device is used as a kneader, it is advantageous if it has a tangential feed line to the container. The material being fed in usually already has a velocity component due to the feed, which can be used to relieve the stirrer during tangential feeding in the container.

[0025] Advantageous embodiments provide that a second concentric deflection device is arranged above the stirrer.

[0026] This second deflection device may comprise a cone arranged concentrically above the stirrer. This cone is shaped like a cone or a truncated cone and facilitates the directing of the material within the device.

[0027] Particularly for use as a kneader with tangential inlet, it is proposed that the second deflection device comprise a truncated cone tapering toward the agitator to redirect the material flow, which is deflected radially inward toward the central axis, toward the agitator. For two agitators arranged one above the other, two truncated cones are used in a corresponding design, with their radially larger circular surfaces adjacent to each other.

[0028] If, however, a central inlet to the device is provided, it is advantageous if the second deflection device has a truncated cone widening towards the stirrer in order to divert the material flow outwards.

[0029] Particularly good mixing results are achieved with devices that have baffles on the radially outer inner wall of the container. This is achieved, for example, with a container that has a peripheral wall that, in the radially outermost region, has at least one circumferential bend with an obtuse angle opening toward the container interior. Preferably, two bends are provided, which also allow for a region of a vertical container wall to be provided between these bends.

[0030] In one method for operating this device, a fill level in the container is preferably set above the first deflection device. This creates a material buffer, and the material itself acts as a pressure on the area where the stirrer is located. For example, when inserting a plate, it should be at the liquid level or only slightly below it. From a technological perspective, the liquid above the liquid level only results in increased water pressure. The area above the constriction should therefore not be flooded at all or only slightly.

[0031] An advantageous process control results if the speed of the stirrer is reduced during filling as the load increases.

[0032] An average speed should be between 3 and 10 m / s at the radially outermost end of the stirrer and in practice about 5 m / s is a good value to combine good mixing with economical energy input.

[0033] The speed of the stirrer can also be adjusted so that the material is forced into the radially outer regions of the container in such a way that in the center of the container, preferably in the area of ​​at least 50% of the axis, all material is driven outwards by centrifugal force.

[0034] Advantageous embodiments of devices according to the invention are shown in the drawing and are explained in more detail below.

[0035] It shows Figure 1 shows a simple embodiment of a device not according to the invention with a round blank, Figure 2 shows an embodiment of the device according to the invention with a truncated cone widening towards the stirrer, Figure 3 shows a device not according to the invention with a feed chamber, Figure 4 shows a device with a tangential inlet and a truncated cone tapering towards the stirrer and Figure 5 shows a device not according to the invention with two stirrers arranged one above the other.

[0036] The Figure 1 The device 1 shown has a container 2 in which a sieve plate 4 is arranged as the base 3. Concentric with the cylindrical container 2, a stirrer 6 is provided on a central axis 5 directly above the base 3. Above the stirrer 6, a horizontally arranged disc 8 with a circular central free passage 9 is provided as the first deflection device 7.

[0037] The stirrer 6 has a coaxial axle body 10 from which six curved arms 11 extend radially.

[0038] The axle body 10 has a diameter 12 in the area of ​​the stirrer 6, the length of which is at least a quarter of the diameter 13 of the stirrer 6.

[0039] The agitator 6 is driven by a gear 14 and a motor 15. This causes the arms 11 to rotate around the central axis 5 to circulate material (not shown) between the disc 8 and the base 3.

[0040] In order for the material to strike the underside of the round blank 8 and be redirected there, the distance 16 between the base 3 and the deflection device 7 is a maximum of half the diameter 17. The diameter 17 is the maximum diameter of the container 2 between the base 3 and the deflection device 7.

[0041] When using the device, material with water is added above the disc 8 into the container 2. The material falls through the free passage 9 into the area below the disc 8 onto the stirrer 6. This stirrer 6 rotates the material in the container 2 between the base 3 and the deflection device 7, whereby the material is driven upwards in the radially outer area by the shape of the container 2 and stirrer 6 and flows upwards until it strikes the underside of the disc 8 and reaches the center 18 of the container. There, the material falls down to the stirrer 6 and is conveyed radially outwards again by the stirrer 6.

[0042] This creates high shear forces between the material particles and good mixing of the material, particularly with coarse or pasty material.

[0043] The material has the lowest peripheral speed in the center of the stirrer 6, which is where clumping is most likely to occur. Therefore, the stirrer features a coaxial shaft body 10, which prevents material accumulation here and redirects the material radially outward toward the stirrer arms 11.

[0044] The Figure 1 shows a particularly small stirrer. A stirrer such as the one shown in device 20 is advantageous. Here, the stirrer 21 has a diameter 22 that is almost as large as the maximum diameter 23 of the container 24 between the deflection device 25 and the bottom 26 of the container 24.

[0045] In this embodiment, the deflection device 25 is a container wall pointing radially inward from the maximum container diameter 21, by means of which a constriction 27 is formed on the container.

[0046] This container has a cone 30 above the coaxial axle body 28 as a second deflection device 29, which is arranged concentrically above the stirrer 21. This cone 30 has the shape of a cone or a truncated cone, the outer surface of which widens towards the stirrer.

[0047] Below the stirrer 21 is a sieve plate 31 and below that is the motor 32 which drives the stirrer 21.

[0048] Material that enters the container 24 tangentially (not shown) or from above is thus deflected radially outwards to the stirrer 21 by the conical surface of the cone 30 and migrates upwards along the inner wall of the container 24 in the radially outer region in order to be deflected radially inwards again by the deflection device 25.

[0049] The Figure 3The device 40 shown has a funnel 41, which merges into a cylindrical collar region 42 and then into a feed chamber 44 delimited at the bottom by a round plate 43. Below the round plate 43, the container 45 widens. There, the peripheral wall in the radially outermost region of the container 45 has a first circumferential bend 46, which merges into a short cylindrical jacket region 47 and forms an obtuse angle 48 open to the inside of the container. Adjoining this at the bottom is a further bend 49, which in turn has an obtuse angle 50 open to the inside of the container 51.

[0050] The material thus reaches the feed chamber 44 either via the funnel 41 or via a tangential feed line 52 and from there through the free passage 53 to the cone 54. In the exemplary embodiment, the free passage has a diameter 55 of approximately one meter.

[0051] The container 45 has no conveyor on the central axis 56 either above the deflection device 43 or below it, which conveys to the agitator 57.

[0052] Also the Figure 4 shows a device 60 with a second concentric deflection device 61 above the stirrer 62. This second deflection device 61, however, has a truncated cone 63 tapering towards the stirrer 62. This truncated cone 63 guides material conveyed into the container 65 through the tangential inlet 64, which is stirred by the stirrer 62 and flows upward in radially outer regions of the container 65, back down to the stirrer 62. A conical peripheral surface 67 concentric with the central axis of the container 65 serves this purpose.

[0053] The motor 68 drives the stirrer 62 via the gear 69, which stirs the material in the container 65. The material initially flows upwards due to the shape of the stirrer, the centrifugal forces, and the shape of the inner wall 70 of the container 65. The material then reaches an inner container wall 71 above the stirrer 62, which acts as the first deflection device and deflects the material toward the central axis 66. The material is then deflected downwards again toward the stirrer 62 via the conical surface 67 of the truncated cone 63. The material thus orbits a central ring axis of a torus, and the stirrer and container shape and the deflection devices are designed to minimize the formation of particularly low-speed zones. This leads to intensive mixing and prevents the formation of lumps.

[0054] The Figure 5shows with the device 80 that the first deflection device does not necessarily have to be a container wall or a container installation, but can also be provided by a second material flow. This device 80 has a container 81 in which a first agitator 84 in the container 81 is driven by a first motor 82 and a first gear 83. Above this is the second motor 85, which drives a stirrer 87 in the container 81 via a second gear 86. The stirrer 87 thus causes a downward material flow, while the stirrer 84 causes an upward material flow. At the point where these material flows meet, the lower material flow forms a deflection device for the upper material flow and the upper material flow forms a deflection device for the lower material flow.The material flow 88 caused by the second stirrer 87 thus forms the first deflection device for the material flow 89 formed by the stirrer 84 towards the container center 90.

[0055] In the center of the container, a double cone 91 is arranged as a coaxial axle body, which has a lower conical shell surface 92 tapering towards the agitator 84 in order to redirect the material flow 89 towards the agitator 84.

[0056] The double cone 91 has on its upper side a conical surface 93 which tapers towards the stirrer 87 and deflects the material flow 88 towards the stirrer 87.

[0057] At the in the Figure 3It is easy to see from the device shown that it is advantageous if the fill level (not shown) is adjusted in the container 45 above the first deflection device 43. This allows the feed space 44 and also the space above it up to the hopper 41 to be used as storage space for material, and with liquid material or a filling with liquid or water, a hydrostatic pressure is created which acts on the material in the area of ​​the stirrer 57.

[0058] To achieve the desired material flow in container 45, it is proposed that the speed of the agitator be reduced as the material load increases during the filling of container 45. This allows for particularly intensive circulation of the material with low power consumption.

Claims

1. A device for treatment of material with a container (2), in which a stirrer (6) rotatable about a central axis (5) is disposed, and with a first deflecting arrangement (7), which is disposed in the container (2) above the stirrer (6), in order to divert a flow of material conveyed by the stirrer (6) towards the center of the container, wherein the stirrer (6) has a coaxial axle body (10), the diameter (12) of which in the area of the stirrer (6) is at least a quarter of the diameter (13) of the stirrer (6), wherein the container (45) has no conveyor on the central axis (5) conveying towards the stirrer (57), wherein the diameter (22) of the stirrer (21) is at least 80% of the maximum diameter (23) of the container (24) between the bottom (26) and the deflecting arrangement (25) and the first deflecting arrangement (25) is formed by a constriction (27) on the container (24).

2. The device according to claim 1, wherein the container (2) has a bottom (3) below the stirrer (6) and a distance (16) between the bottom (3) and the deflecting arrangement (7) is at most half the maximum diameter (17) of the container (2) between the bottom (3) and the deflecting arrangement (7).

3. The device according to one of the preceding claims, wherein the stirrer (6) has one or several arms (11), which extend radially outward from the coaxial axle body (10).

4. The device according to one of the preceding claims, wherein the first deflecting device (7) has a disc (8) with a central free aperture (9) disposed in the container (2).

5. The device according to one of the preceding claims, wherein the first deflecting device (7, 43) has a central free aperture (9, 53) with a diameter (55) of at least 0.8 m.

6. The device according to one of the preceding claims, wherein the container (45) has a feed chamber (44) above the deflecting device (43).

7. The device according to one of the preceding claims, wherein it has a tangential supply line (52) to the container (45).

8. The device according to one of the preceding claims, wherein it has a second concentric deflecting arrangement (29, 61) above the stirrer (21, 62).

9. The device according to claim 8, wherein the second deflecting device (29) has a cone (30) which is concentrically disposed above the stirrer (21).

10. The device according to one of the claims 8 or 9, wherein the second deflecting arrangement (61) has a truncated cone (63) tapering towards the stirrer (62) in order to divert the material flow, which is deflected radially inwards towards the central axis (66), towards the stirrer (62).

11. The device according to claim 8 or 10, wherein the second deflecting arrangement (29) has a cone (30) or truncated cone that widens towards the stirrer (21) in order to divert the material flow radially outwards.

12. The device according to one of the preceding claims, wherein the container (45) has a circumferential wall (46) which, in the radially outermost area, has at least one circumferential bend (46, 49) with an obtuse angle (48, 50) open towards the inner side of the container.

13. A method for operating a device according to one of the preceding claims, wherein in the container (45), a filling level is set above the first deflecting arrangement (43).

14. The method according to claim 14, wherein during the filling process, the rotational speed of the stirrer (57) is reduced as the load increases.