WO2001005691A1

WO2001005691A1 - Material device for supplying material in the form of fine particles or in powder form

Info

Publication number: WO2001005691A1
Application number: PCT/EP2000/006755
Authority: WO
Inventors: Ralf Zawal; Volkmar Irmscher
Original assignee: Möller-Fuller Bulk Handling Gmbh
Priority date: 1999-07-19
Filing date: 2000-07-14
Publication date: 2001-01-25
Also published as: DE19933707A1; AU6273900A

Abstract

The invention concerns a device for supplying material in the form of fine particles or in the form of powder, from a zone at ambient pressure to a zone of higher pressure, preferably connected to a pneumatic conveyor pipe. Said feeding device comprises a housing (10) wherein is placed an endless screw (32) preferably driven by an electric driving member (22), and designed to transport the material from a material intake (38), through an endless tubing (36), up to a material outlet (40) located at one end of the endless tubing (36). The material outlet (40) can be closed preferably by a closure member (42) and emerges into a dispensing chamber (14). The end of the endless screw shaft (32) is located at some distance from the material outlet (40). A fixed cylindrical core (48) extends from the latter (40) towards the endless screw shaft and coaxially thereto. The turns (34) of the endless screw enclose the core, beyond the shaft end.

Description

Feeder for finely divided or powdery material

The invention relates to a loading device for supplying finely divided or powdery material from a room with ambient pressure into a room with increased pressure according to the preamble of patent claim 1.

Free-flowing goods such as coal dust. Cement, etc. are often conveyed pneumatically. There is naturally a pressure in the delivery line that is higher than the ambient pressure. It is therefore necessary to enter the material in the delivery line against the increased pressure. The funding used for this in general and for a long time is a screw conveyor or screw pump. At one end, it picks up the material that is fed in under ambient pressure and conveys it in the direction of a delivery chamber, which is connected, for example, to a pneumatic conveying line. During transport, the goods are partially compressed, which creates a seal between the inlet and outlet of the conveyor line. If a seal were not present, there would be a risk that conveying air would escape through the material inlet and the conveyor operation would collapse. In addition, there is a risk that filled material is whirled out through the outlet. Both phenomena are extremely undesirable.

From DE 22 49 453 it is known to convey given free-flowing material into an expansion chamber with the aid of a first screw conveyor, whereby At the outlet of the screw tube of the first screw conveyor, a plunger head is arranged, which can be set in rotation and can be moved back and forth. It is equipped with cutting elements. The lower outlet of the expansion chamber is connected to the inlet of a further screw conveyor, which then feeds the material into a reactor or the like. The arrangement described creates an effective decoupling between the pressure conditions at the input and output location. However, the known conveyor is relatively complex and requires a lot of space.

It is also known to arrange a valve at the outlet of the screw conveyor which acts as a check valve and is intended to prevent air from flowing from the higher pressure area to the lower pressure area. From DE 25 07 768 it is known to use a flap for this purpose which is pivotally mounted on a pivot lever. For example, the flap can be biased into the closed position by gravity. In this context, it is also known to design the flap in a ring-like manner; it surrounds the worm shaft, which is supported at both ends and extends through the dispensing chamber. In this context, it is also known to arrange a further screw spiral in the conveying direction in front of the bearing, the direction of rotation of which is opposite to the direction of rotation of the screw conveyor. to prevent material from entering the storage chamber from the dispensing chamber.

From EP 0 055 831 it is known to arrange a conically widening chamber between a cantilevered screw and the material outlet. This not only creates a sufficient space for the sealing material to prevent air recoil, but also because of its expansion in the conveying direction - j - ensure that a wedge effect supports the seal opposite to the direction of conveyance.

From DE 24 1 1 393 a screw conveyor has become known in which the screw spiral has a reduced pitch near the material outlet. In this way, compression of the material near the outlet is to be achieved.

From DE 34 44 816 it has become known to provide two outlets at the end of the screw tube, each of which is provided with a flap valve. In this way, larger amounts of material can be enforced. The special arrangement of the material outlets also ensures simple and uncomplicated conveying of the material with the help of gas.

From DE 35 45 339 a screw conveyor has become known, in which the screw tube is lined with a flexible, abrasion-resistant material in the form of an exchangeable sleeve against which the screw thread rests. A narrowing of the conveyor cross section is provided in the area of the discharge end of the screw conveyor. Furthermore, the worm tube and / or worm shaft with the worm thread are arranged axially displaceably.

In most screw conveyors of the type described, gas sealing through the material near the outlet is sought. If this result is achieved in the form of a gas-impermeable plug, there is a risk that the frictional forces that occur will be high and that the energy consumption for the worm drive will assume considerable values. The throughput is naturally lower with compression. The compression also depends on the pitch of the screw spiral. ever the greater the pitch at the same speed, the greater the material throughput. A small pitch, on the other hand, requires more effective compression with reduced material throughput.

The invention has for its object to provide a loading device of the type mentioned, which has a relatively low energy consumption with a large throughput per unit time and achieves an effective seal even with a high pressure difference.

This object is achieved by the features of patent claim 1.

In the feed device according to the invention, the screw conveyor is also overhung. Your wave ends at a distance from the outlet. In principle, this is known. In the invention, however, the screw spiral extends beyond the end of the shaft and surrounds a stationary core, which extends from the outlet in the direction of the screw shaft. The core can be brought directly to the blunt end of the worm shaft with a minimal gap without any noticeable inhibiting forces being generated due to material penetrating into the gap. The core preferably extends into an area in which no appreciable pressure build-up takes place yet. The diameter of the core near the shaft end corresponds to the diameter of the shaft end, as does its outer contour, which is circular in cross section. According to one embodiment of the invention, the core can taper in the direction of the outlet, so that a conical annular chamber is formed between the worm tube and the worm shaft that widens toward the outlet and has the known advantages already described above. Due to the friction between the screw helix and the material being conveyed, the plug that is being formed is rotated with the screw. In the device according to the invention, a fixed core is provided in the area of the plug formation, which opposes a frictional resistance to the plug which tends to rotate. Another frictional resistance is generated by the stationary screw tube. The design of the screw conveyor according to the invention therefore leads to a significantly reduced rotation of the stopper formed or even to a standstill in the direction of rotation, so that it behaves like an only axially movable, non-rotatable spindle nut. In this way, a relatively highly compressed, homogeneous stopper is obtained which forms an effective seal against air passage and which nevertheless offers far less resistance to the conveying of the material than known screw conveyors. Therefore, the energy consumption in the loading device according to the invention is relatively low.

In the device according to the invention, the screw spiral can be brought close to the inside of the core without coming into contact with it. It is understood that the screw spiral is sufficiently stable. to effectively counteract yielding deformations due to occurring forces.

According to another embodiment of the invention, a multi-start screw helix is provided, which has two or more gears, for example. This can significantly reduce the length of the screw. For example, according to an embodiment of the invention, it only needs to be a length of 0.7 to 1.5 turns. It has already been mentioned that the fixed core, which can be connected to the housing via radial webs, can be tapered towards the outlet. Accordingly, the screw tube can be conical near the outlet and expand towards the outlet to form the conical annular chamber already mentioned.

In another embodiment of the invention it is provided that the screw conveyor is arranged vertically. This has two advantages. One is that the material flow through the loading device is improved by gravity. In addition, the vertical arrangement enables a compact design, in particular when the drive motor can be arranged next to the worm housing. The material is fed laterally, e.g. B. by means of a pneumatic conveyor trough.

With the vertical arrangement of the screw, it is also advantageous if the screw spiral begins at a distance below the lateral material inlet. The lower screw has the advantage that material cannot be thrown out of the housing so easily. In addition, there is a better degree of filling.

According to another embodiment of the invention, the screw is coated with a high-strength, low-friction material. Such a material is preferably a diamond-like carbon. Such a coating process (DLC process - diamond-like carbon) works with a high-frequency glow discharge and leads to coatings with a very low coefficient of friction. This further reduces the tendency of the plug formed near the outlet to rotate with the screw. Due to the vertical arrangement of the worm shaft, a compressed air mechanical seal above the material inlet can advantageously be used to seal the drive shaft, thereby preventing fine dust-like material from penetrating into the bearing.

The invention is explained in more detail below with reference to an embodiment shown in the drawings.

Fig. 1 shows partially in section a loading device according to the invention.

FIG. 2 shows an enlarged view of the slide bearing of the device according to FIG. 1.

FIG. 3 shows the bottom view under the ring piston of the slide bearing according to FIG. 2.

FIG. 4 shows another embodiment of a dispensing chamber for a device according to FIG. 1.

Fig. 5 shows a further embodiment of a loading device according to the invention.

A snail housing 10 is supported in a vertical arrangement on a base 12, in which a delivery chamber 14 is formed. which is triangular in cross section and is connected to a pneumatic delivery pipe. The dispensing chamber can also be cylindrical. In Fig. 1, the outlet 16 of the delivery chamber 14 is shown. A bearing housing 18 is flange-mounted on the worm housing 10, on which in turn a gear housing 20 is flange-mounted, which extends laterally beyond the housing 10, 18 and holds a drive motor 22 on its underside. The drive motor is coupled via a belt drive 24 shown in dashed lines to a gearwheel 26 which is seated on the end of a drive shaft 30. The drive shaft 30 is rotatably connected to a worm shaft 32 at the lower end. The connection is not discussed in detail here. The worm shaft 32 carries a two-start worm helix 34 of a worm 35. The two gears simply extend around the axis of the worm shaft 22. The worm 35 is located within an annular cylinder 36 (worm tube), which is fixedly arranged in the housing 10. The housing has a side material inlet 38. It can be seen that the screw 35 is lower than the inlet 38.

As can also be seen in FIG. 1, the end of the cylinder 36 is designed as an outlet 40 for material to be conveyed. The outlet is closed in Fig. 1 by an annular flap 42 as a valve member which is gimbal-mounted on a lever 44. A spring, not shown, biases the flap 42 towards the outlet 40.

The worm shaft 32 ends bluntly at 46 at a great distance from the outlet 40. The contour of the worm shaft 32 continues downward in the form of a fixed core 48 which is fastened to the cylinder 36 via three radial webs 50 which are spaced apart at the same distance. As can be seen, the worm coils 34 extend downward over the end 46 of the worm shaft 32 and wind around the core 48 at a close distance. The core 48 is conical and tapers in the direction of the outlet 40. The inner diameter of the cylinder 36 increases below the end 46 of the worm shaft 32 in the direction of the outlet, as a result of which Core 48 and cylinder 36 an expanding conical annulus is formed.

The small-sized, free-flowing material fed laterally via the inlet 38 first falls into a shaft before it is gripped and moved forward by the screw spirals 34. In addition to the transport, the material is compressed, as a result of which a stopper is formed, which seals against the increased pressure in the delivery space 14. The material of the screw coils 34 is preferably provided with a highly resistant coating with a low coefficient of friction, for example with diamond-like carbon. As a result, the frictional resistance of the screw spiral during transport of the material is relatively low. On the other hand, the cylinder wall and the outer surface of the core 48 have a higher coefficient of friction. This counteracts the tendency of the plug to rotate with the screw and the plug acts as a non-rotatable nut which moves axially in the direction of the outlet 40. In this way, a homogeneous, relatively well sealing plug is achieved. This type of compression can be accomplished with relatively little energy.

The drive shaft 30 is supported at 52, 54 by roller bearings in the bearing housing 18. Below the roller bearing 54 is a compressed air mechanical seal 56. This is to be explained in more detail with reference to FIGS. 2 and 3.

A ring 58 is arranged between the screw conveyor housing 10 and the bearing housing 18 and has a downward-facing axial collar 60 with a groove for receiving an O-ring 62. A further ring 64 surrounds the collar 60 at a radial distance the ring 58 connected. A groove in the ring 64 receives an O-ring 66. An annular piston 68 is arranged in a floating manner between the collar 60 and the ring 66. It is guided laterally through the O-rings 62, 66 in a sealing manner. A disk 70 is fixedly connected to the drive shaft 30. It has a conical surface on the circumference. which corresponds to the conical surface of the ring 64, so that a conical gap 72 of relatively small width is formed. There are several channels 74 in the ring, which are connected to a circumferential annular space 75 via a transverse bore. The annular piston 68 has a plurality of axially parallel bores 76 arranged uniformly in the circumferential distance. which each open into a chamber section 78. The channels 74 are connected to a compressed air source (not shown), so that a pressure cushion is built up in the annular space 75 and in the individual chamber sections 78. In this way, an air cushion is generated in the chamber sections 78 and the annular piston 68 is at a small, albeit very small, distance from the assigned surface of the disk 70. There is therefore an almost frictionless storage, which at the same time ensures that no contaminants penetrate into the bearing housing 18 from the inside of the screw housing 10. Excess compressed air escapes through the gap 72 and prevents the ingress of contaminants.

4 shows a dispensing chamber 14a which is formed by a cylindrical housing 12a. An annular valve member 42a can be seen. which is similar to the annular flap 42 according to FIG. 1. In FIG. 4, however, the valve member 42a is suspended by three springs 80 arranged uniformly in the circumferential distance, specifically via L-shaped arms 82 which are attached to the underside of the valve member 42a are and extend radially outward. The springs 80 are attached at the other end to the housing of the device, not shown. Thereby the valve member 42a is biased towards the sealing seat. As soon as a delivery pressure occurs, the valve member 42a is moved downward to release a gap or the inner passage. The valve member 42a can optimally adapt to the pressure conditions due to its suspension. In addition, the springs 80 enable a smaller housing 12a for the chamber 14a in relation to the housing 12 of the dispensing chamber 14.

The remaining details shown in FIG. 4 can already be found in FIG. 1 and will not be explained here again.

As far as the same parts are used in the embodiment according to FIG. 5 as in those according to FIGS. 1 to 4, the same reference numerals are also used. The special feature of the embodiment according to FIG. 5 is that a further screw spiral section 90 is arranged on the screw shaft 32a above the first screw spiral section 34, the pitch of which is greater than that of the first screw spiral section 34. The second screw spiral section 90 extends beyond the inlet 38 above, it has the task of pre-compressing the supplied material so that trapped air, which necessarily escapes during compression, can be removed. In the embodiment according to FIG. 5, this is done approximately in that the inlet area for the inlet 38a is divided by a sheet metal, so that a passage into and out of the cylinder 10a, which run approximately parallel in the vicinity of the cylinder 10a, are created. The air, which is displaced by the screw spiral sections when composing the material, can escape via the second pass.

In an alternative embodiment, not shown in the drawing, the second screw spiral section 90 can be at the top at the level of the lower edge of the Inlets 38a end, and the worm shaft 32a is surrounded by a sleeve-shaped section with a radial spacing. The supplied material that is anyway thrown radially outwards by the centrifugal force against the inner wall of the cylinder 1 Oa. gets into the outer area of the conveyor section, while the displaced air collects radially further inwards and flows upwards. It flows upwards in the area of the inlet through the annular gap between the worm shaft and the sleeve-shaped section and can be released there in a suitable manner. The sleeve-shaped section prevents the supplied material from interfering with this flow.

SPARE BLADE (RULE 26)

Claims

- 1 y - Claims:

1. Feeding device for supplying finely divided or powdery material from a room with ambient pressure into a room with increased pressure, which is preferably connected to a pneumatic conveying line, with a housing in which a screw conveyor, preferably driven by an electric drive, is arranged for transporting the material from a material inlet through a screw tube to a material outlet arranged at the end of the screw tube, which can preferably be closed by a valve member and opens into a discharge chamber, characterized in that the screw shaft (32) ends at a distance from the outlet (40) and from the outlet towards the screw shaft and coaxially to this extends a fixed cylindrical core (48) around which the screw helix (34) winds beyond the shaft end (46).

2. Device according to claim 1, characterized in that the screw helix (34) is brought close to the inside of the core (48).

3. Apparatus according to claim 1 or 2, characterized in that a multi-start screw conveyor (34) is provided.

4. Device according to one of claims 1 to 3, characterized in that the length of the screw helix or an inner screw helix section is 0.7 to 1.5 turns.

5. Device according to one of claims 1 to 4, characterized in that the outer diameter of the screw conveyor is constant.

6. Device according to one of claims 1 to 5, characterized in that the inner diameter of the screw tube (36) on the shaft end (46) is constant and the screw tube (36) widens conically from there towards the outlet (40).

7. Device according to one of claims 1 to 6, characterized in that the core (48) is conical and at the shaft end (46) has the same diameter as the worm shaft (32) and tapers towards the outlet (40).

8. Device according to one of claims 1 to 7, characterized in that the core (48) by means of radial webs (50) is connected to the housing (10).

9. Device according to one of claims 1 to 8, characterized in that the screw conveyor is arranged vertically.

10. The device according to claim 9, characterized in that the drive motor (22) is arranged near the worm housing (10) and is coupled via a chain or belt drive (24) to the drive shaft (30) of the screw conveyor.

1 1. Device according to claim 9 or 10, characterized in that the screw spiral (34) begins at a distance below the lateral material inlet (38).

12. The device according to one of claims 1 to 1 1, characterized in that the screw spiral (34) is coated with a high-resistance coating with a low coefficient of friction.

13. The apparatus according to claim 12, characterized in that a coating of diamond-like carbon is provided.

14. Device according to one of claims 1 to 13, characterized in that the valve member is a flap (42) which is gimbal-mounted on a pivot lever (44).

15. The device according to one of claims 1 to 13, characterized in that the valve member is suspended and biased by at least three springs.

16. The apparatus according to claim 14 or 15, characterized in that the valve member is annular.

17. Device according to one of claims 9 to 16. characterized in that the drive shaft (30) has a compressed air mechanical seal above the material inlet (38).

18. Device according to one of claims 1 to 17, characterized in that with the worm shaft (32a) above the first helical section (34), a second helical section (90) is connected.

19. The apparatus according to claim 18, characterized in that the second helical section (90) has a greater slope than the first.

20. The apparatus according to claim 18 or 19, characterized in that the lateral material inlet (38 a) is arranged above or at the upper end of the second screw section (90).

21. The apparatus according to claim 20, characterized in that the lateral material inlet (38a) is divided into two passages, preferably by a sheet, one of which serves for the entry of the material and the other for the exit of air.

22. The apparatus according to claim 20, characterized in that the worm shaft above the second helical portion at the level of the lateral material inlet is surrounded by a sleeve-shaped section at a lateral distance and that an outlet for air is provided above the sleeve-shaped section.