EP1992894B1 - Device for removing water from bulk or flowable feed material through its compaction - Google Patents

Description

The invention relates to a device for dewatering pourable or flowable feed material by its compression according to the preamble of patent claim 1.

In plant and process engineering, a starting material is usually processed in the course of its successive processing to the desired end product. This is usually done gradually during its passage through various processing stations.

An example of such a type of processing is the processing of lignocellulosic material, such as wood, annual plants, straw, bagasse and the like. Here, one after another, the processing stations undergo pre-shredding, washing, dewatering, pre-steaming, dewatering, cooking, defibering, drying and separating. The fibers thus obtained can then be used for pulp production in papermaking or as wood fibers in the production of wood fiber products, such as MDF products.

The invention relates to a device with which the feed material is drained by its compression. In the process described above, such a device may be arranged, for example, as a stuffing screw in front of a digester, with the function to allow the entry of the free-flowing feed into a subsequent pressurized system while dewatering the feed.

The basic structure of such a device provides a housing with a jacket tube, in which rotates a occupied with a rotating coil worm shaft, which transports the still loose feed material in cooperation with axially aligned conveyor strips to the opposite end of the jacket tube. As a result of the conical tube tapering towards this end or the decreasing pitch of the helical screw, the feed material is strongly compressed and the residual water present in the feed material is squeezed out. The discharge of the squeeze occurs through openings in the jacket tube, which are adapted in their shape and size of the nature of the feed.

In addition to squeezing out the residual water, the compaction of the feed also serves to create a high density plug of material which seals the inlet opening from the pressurized system of the digester.

A disadvantage of such devices results from the high compression of the feed material with the result of high contact forces on the inside of the screw shell. These cause high wear both on the screw flight and on the jacket tube, so that known devices are renewed or aufzupanzern at regular time intervals. The associated downtime and work diminish the economic operation of such devices.

Another disadvantage arises from the fixed geometry of the elements involved in the drainage, which makes it impossible to adapt known devices to the feed material which varies in each case.

Furthermore, from the US 3,065,689 a press screw for dehydration of feed material known, with a rotating within a cylindrical housing about the longitudinal axis of the worm shaft, which is provided over its circumference with helices. In the longitudinal section associated with the helixes, the housing is formed with two shells with an outer sheath with larger drainage openings and an inner sheath with smaller drainage openings through which the free water can escape from the feed material. At its end, the worm shaft merges into a helical axial pin, which is surrounded at light radial distance by an elastic ring tube, which in turn is supported on the outside of the rigid housing. By more or less strong filling of the annular tube, there is a targeted radially inwardly directed expansion of the annular tube, which determines the size of the annular passage gap in the region of the axial pin and thus the flow resistance of the feed material in this area. An increase of the flow resistance causes in the upstream region of a greater compression and therefore more intensive drainage, however, a reduction of the flow resistance causes the opposite.

The GB 904,328 discloses a screw press with two axially parallel, laterally spaced worm shafts whose ends are each in shaft bearings are held. The worm shafts, which are equipped with spirals, rotate in opposite directions, whereby the spirals intermesh. The worm shafts are surrounded by a sieve basket-like housing in the area of the helices. By increasing the diameter of the worm shaft in the conveying direction with constant housing cross-section, a compaction of the feed material and thus a drainage is achieved. The water is discharged radially through the screen basket, while the discharge of the dewatered feed material takes place at the end of the housing.

In the US 3,230,865 a worm filter press is described, whose inside a housing rotating screw shaft is hollow and formed with radial openings in the shaft jacket. The compressed against a conical closure member feedstock is acted upon at the same time with a gas emerging from the openings in the worm shaft in order to reduce the moisture content of the feedstock even during the drainage in addition.

Finally, the shows EP 0 367 037 a press screw separator whose worm shaft, which is also occupied by helices, rotates within a cylindrical housing. The housing is subdivided in the conveying direction into a feed area, a drainage area and a discharge area. The drainage area forms a screen basket whose radial passages allow the outlet of the water from the housing. The solid plug formed during this process takes over the centering and storage of the worm shaft in the area free of filaments. The discharge of the Feststoffpfropfens from the press screw separator via a subsequent to the drainage area tubular mouthpiece.

Against this background, the invention has for its object to further develop generic devices in terms of their cost-effectiveness.

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

Advantageous embodiments will be apparent from the dependent claims.

The basic idea of the invention is to make the inner lateral surface of the device simple and quickly replaceable, at least in the heavily stressed areas. This is achieved by separating the functional components into those having statically supporting function and those with drainage function. The supporting function takes over the massive housing or casing tube of the device, which is provided with respect to the nature of the feed material with relatively large passages. The dewatering function, that is the separation of the feed from the crushed water, comes to the relatively slender inner tube, which at the Supported inside circumference of the casing tube and has in the region of the passages adapted to the nature of the feed passages for the crushed water. This division of the functions allows a targeted adaptation of a device according to the invention both to static and procedural requirements with the aim of achieving an optimization of both the structural design and the quality of the processing.

Due to the very slender design of the parts ensuring the dewatering function, in contrast to the prior art, where the passage openings have a three-dimensional character due to the thickness of the jacket tube and smallest particles in the feed material entail the risk of clogging of the openings, a substantially two-dimensional drainage area is created in which blockages of the openings are not to be feared. Due to the formation of the passage openings as a stepped bore, this effect is further increased. As a result, it is possible to select the cross-section of the passage openings as a whole smaller and thus proportionately to reduce the passage of solid particles through the passage openings.

Since the inner shell surface forming parts are very slim, they can be made without high increase in the cost of high-strength material and therefore counteract too rapid wear. As a result of longer machine service life and maintenance intervals, this results in an additional economic advantage for the operators of devices according to the invention.

In the interaction of the above-mentioned functional components has been found to be advantageous if the surface of the openings in the inner tube is about 20% to 40%, preferably 25% to 30% of the cross-sectional area of the passages in the jacket tube and plug tube. Here is a balance between sufficient strength at a large dewatering performance.

In practice, passage openings with a diameter of 2 mm to 10 mm, preferably from 4 mm to 8 mm, have proven to be suitable. However, other diameter ranges are also within the scope of the invention.

It proves to be advantageous, the passage openings in such a way that they expand in the direction of passage, which can be done both conically and in stages. In this way, the flow resistance decreases radially outwardly, which is conducive to the discharge of the squeeze and prevents blockages of the passages.

In order to minimize wear, it is sufficient for the device to be designed according to the invention only in the end region of the jacket tube or in the area of the plug tube, since there are the regions of greatest compression and thus of the greatest wear.

In embodiments of the invention with a bearing journal at the end of the drive shaft, the compression in the region of the plug tube can be influenced in a targeted manner by a corresponding pin shape. For example, the compression is increased by a conically widening in the conveying direction bearing pin in Pfropfenrohr. By decreasing towards the end diameter of the journal, a gradual relaxation of the feed material can be achieved while a cylindrical bearing journal behaves neutral.

Furthermore, it is advantageous to form the end of the jacket tube as an independent component in the form of a plug tube, which facilitates maintenance and repair work.

In a simple embodiment of the invention, the inner tube is screwed to the jacket tube or plug tube to prevent relative movements of the two parts to each other. An alternative which is advantageous with regard to rapid installation or replacement of the inner tube provides positive-locking means which, while permitting axial insertion of the inner tube, block twisting relative to the outer tube. In the axial direction, movement of the inner tube relative to the jacket tube is prevented by stops.

• Fig. 1 einen vertikalen Längsschnitt durch eine erfindungsgemäße Vorrichtung,
• Fig. 2 einen vertikalen Querschnitt durch die in Fig. 1 dargestellte Vorrichtung entlang der dortigen Linie II-II,
• Fig. 3 einen horizontalen Längsschnitt durch den in Fig. 2 dargestellten Bereich entlang der dortigen Linie III-III,
• Fig. 4 einen vertikalen Teilquerschnitt durch eine andere Ausführungsform der Erfindung und
• Fig. 5 einen vertikalen Längsschnitt durch eine weitere Ausführungsform einer erfindungsgemäßen Vorrichtung.

The invention will be explained in more detail with reference to an embodiment shown in the drawings. It shows

• Fig. 1 a vertical longitudinal section through a device according to the invention,
• Fig. 2 a vertical cross section through the in Fig. 1 shown device along the local line II-II,
• Fig. 3 a horizontal longitudinal section through the in Fig. 2 shown area along the local line III-III,
• Fig. 4 a vertical partial cross section through another embodiment of the invention and
• Fig. 5 a vertical longitudinal section through a further embodiment of a device according to the invention.

In Fig. 1 One sees a device according to the invention in the form of a plug screw 1 with a housing 3 arranged around a horizontal axis of rotation 2. The housing 3 comprises a cylindrical feeding area 4 into which a feed hopper 5 opens from above. The front-side housing closure 6 of the housing 3 is equipped as a shaft bushing 7 with bearings for a drive shaft 8 running along the axis of rotation 2. The drive shaft 8 leads with its lying outside of the housing 3 end to a rotary drive, not shown.

On the side opposite the housing closure 6 side of the cylindrical application area 4 includes a conically tapered jacket tube 9, which is secured via annular flanges coaxially on the cylindrical task area 4. In this way, results in the axial direction along the axis of rotation 2, a continuous conveying and compression chamber 10. At the conveying and compression chamber 10 defining inner surfaces can be seen approximately axially aligned feed grooves 11, which are distributed uniformly over the inner circumference. In the jacket tube 9 radial dewatering openings 12 are additionally introduced, via which the pinch water emerging in the course of compression is derived from the feed material.

The drainage pipe 9 is peripherally surrounded by a cylindrical plate 13, which forms in this way a sump for the 38 designated squirting water. At the bottom you can see an outlet 14 for the squirting water and at the apex of an outlet 15 for escaping air and escaping steam.

In the conveying and compression chamber 10 extends along the axis of rotation 2, the drive shaft 8, along the circumference of a helix 16 rotates helically. According to the course of the jacket tube 9 in the conveying and compression chamber 10, the outer diameter of the helix 16 decreases and acts to ensure the axial transport of the feed with the conveyor belts 11 on the inner circumference of the conveying and compression chamber 10 together.

The end of the drive shaft 8 forms a bearing pin 17 which is surrounded by a so-called plug tube 18. The plug tube 18 represents the axial extension of the jacket tube 9 and has to accomplish the task of a tight and pressure-resistant connection to the downstream areas of the process technology, for example, operated with an overpressure digester. The connection is formed by high-density, a graft-forming feed material, which also represents the radial bearing for the bearing pin 17.

The closer construction of the plug tube 18 results additionally from the Fig. 2 and 3 , From which it is apparent that the plug pipe 18 has a coaxial to the rotation axis 2, formed from two half-shells cylindrical pipe section 19, at both ends of which an annular flange 20 and 21 is integrally formed. The annular flanges 20 and 21 serve on the one hand for connection of the plug tube 17 to an attached at the end of the jacket tube 9 annular flange and on the other hand to provide a mounting option for a connecting line 22 for forwarding the compacted feedstock to subsequent processing stations.

The annular flanges 20 and 21 are peripherally surrounded by two half-shell-shaped troughs 23 and 24, which are assembled into a cylindrical structure. Each of the trays 23 and 24 comprises two semicircular support profiles 25, on the outer circumference of a circular plate 26 is attached. About opposing longitudinal flanges 27, the trays 23 and 24 are assembled to form a hollow cylinder which completely surrounds the plug tube 18 in the finished state and is absorbed in the squish 38 from the feed material. In the bottom region of the lower tub 24, one sees an outlet 28 for discharging the collected squeeze water 38.

In the axial overlap region with the bearing pin 17, the pipe section 19 of the plug pipe 18 has radial passages 29 of rectangular shape, which are arranged distributed in two axially staggered radial planes over the circumference, so that in this area results in a loch-like structure in a small space. The passages 29 associated with the end of the jacket tube 9 can also narrow outwards over the wall thickness of the tube section 19.

In the region of the passages 29, the pipe section 19 is turned out on its inner circumference, so that a stepped inner diameter enlargement results. This serves as a receptacle for an inner tube 30 which is axially inserted into the plug tube 18 in this way until it finds a stop with its end face on the annular shoulder 31 formed by the step. In this case, the inner tube 30 terminates flush with the end face of the plug tube 18 at the other end.

The inner tube 30 can be assembled with advantages for a quick assembly and disassembly both one-piece and two half-shells and consists of a wear-resistant material. The attachment and securing position of the inner tube 30 in the stopper tube 18 via screws 33 which extend radially through the cylindrical tube portion 19 of the stopper tube 18 and with its thread into it until in the Cross-sectional area of the conveyor ribs 32 engage extending threaded holes in the inner tube 30. In this way, the clamping force from the screws 33 is distributed over the conveyor ribs 32 over a large area on the inner tube 30.

The inner tube 30 has a plurality of drainage regions 34 which are distributed over the circumference congruent to the passages 29. Each drainage region 34 has a multiplicity of sieve openings 35 lined up in a sieve-like manner, through which the pinch water 38 passes out of the stopper tube 18. The passages 29 and the passage openings 35 thus cooperate in the discharge of the squeeze 38.

During operation of a device according to the invention, the feed material, as indicated by the arrow 36, is poured loose into the feed hopper 5, in which it slips down due to gravity and into the catchment area of the stuffing screw 1 arrives. There it is detected by the helices 16 and transported in the direction of the arrow 37. As a result of the delivery and compression space 10 continuously decreasing in the conveying direction 37, the feed material is continuously compressed until it has its greatest packing density at the end of the jacket tube 9. The first squeezed due to the increasing compression water 38 passes through the drainage holes 12 in the formed of the cylindrical plate 13 drip tray and is disposed of via the outlet 14.

In order to additionally be able to extract water from the compressed feedstock, it is also possible for free water in the region of the inner tube 30 and thus in the region with the greatest pressure to escape from the device through the through-openings 35 and radial passages 29 in the trough 24 to be collected and discharged via the outlet 28.

In Fig. 4 an embodiment of the invention with alternative design of the inner tube 30 'is shown. Fig. 4 otherwise corresponds to the in Fig. 2 shown partial cross section, so that the same reference numerals are used for identical parts.

This in Fig. 4 shown inner tube 30 'is composed essentially of strip-shaped arc segments 40 which are inserted axially into the plug tube 18 until the drainage regions 34' are aligned radially with the passages 29 in the plug tube 18. The inwardly directed longitudinal edges 41 of the strip-shaped arc segments 40 are chamfered.

The attachment of the arcuate segments 40 by means also bow segments performing conveyor belts 32 ', which are clamped by screws 33 radially outward against the inner surface of the pipe section 19. The foot region of the conveyor strips 32 'tapers in the direction of its contact surface on the inner circumference of the plug tube 18, so that the sides of the conveyor strips 32 form wedge surfaces which cooperate with the chamfered longitudinal edges 41 of the arc segments 40. When tightening the screws 33 thereby creates a clamping action of the arc segments 40, which ensures a secure fit within the same within the plug tube 18. This type of attachment has the advantage that even individual arc segments 40 can be replaced.

FIG. 5 relates to a device for the above-described stuffing screw 1 largely identical, so again apply the same reference numerals for the same parts. Differences exist only in the end region of the jacket tube 9 ', which in the conveying direction 38 in about the last third of a Pfropfenrohr 18 comparable pipe section 41 with passages 29' is formed. Within the tube section 41, one can see an inner tube 30 "which is comparable in design and purpose to the inner tube 30. The inner tube 30" has a multiplicity of drainage regions with passage openings 35 'which are aligned in the radial direction with passages 29' in the jacket tube 9 '. To constructive details that already applies under the FIGS. 1 to 4 said. This embodiment of the invention has the advantage that in addition to an effective drainage a simple and quick change of directly affected by wear the inner periphery of the device forming parts not only in the area of the journal 17, but also in the last section of the jacket tube 9 ', in which the Drive shaft 8 is still occupied by helices 16, is possible.

Claims (16)

1. A device for dewatering bulk or free-flowing input material by compacting it in a housing (3) arranged along an axis of rotation (2), the housing having an input area (4) and a feed and compaction area (10) following axially within a jacket pipe (9, 9') and a drive shaft (8) having circumferentially extending coils (16) configured to rotate coaxially in the housing (3) and ending in conveying direction (37) in a coil (16) free bearing pin (17) for compacting the input material during transport from the input area (4) through the feed and compaction area (10), wherein residual water (38) in the input material is discharged from the device through the radial passages in the jacket pipe (9, 9'), and with a plug pipe (18) connected axially to the jacket pipe (9,9') in conveying direction, characterized in that the plug pipe (18) extends over the longitudinal section of the bearing pin (17) and that, where it overlaps the bearing pin (17),it has radial passages (29) allowing a radial dewatering of the input material also in the area of the plug pipe (18), wherein the plug pipe (18) is provided with an inner pipe (30) that extends over the longitudinal section of the bearing pin (17) and lies at least partially with its external circumference against the inner circumference of the plug pipe (18) and has, at least in the area of the passages (29), passage openings (35) that are much smaller than the passages (29) in the plug pipe (18).
2. The device in accordance with claim 1, wherein the cross sectional surface of the passage openings (35, 35') in the plug pipe (18) is 20% to 40% of a cross sectional surface of the passages (29, 29'), preferably 25% to 30%.
3. The device in accordance with one of the claims 1 or 2, wherein the passage openings (35, 35') in the inner pipe (30, 30', 30") have a diameter of 2 mm to 10 mm, preferably 4 mm to 8 mm.
4. The device in accordance with one of the claims 1 to 3, wherein the passage openings (35, 35') are formed from stepped holes having a larger diameter towards the radially outward area.
5. The device in accordance with one of the claims 1 to 4, wherein the passage openings (29, 29') are distributed in several radial planes over the circumference of the plug pipe (18).
6. The device in accordance with one of the claims 1 to 5, wherein the inner pipe (30") extends over approximately the last one-third in the feed direction (37) of the longitudinal section of the drive shaft (8) equipped with a coil (16).
7. The device in accordance with one of the claims 1 to 5, wherein feed strips (32, 32') are arranged on the inner circumference of the inner pipe (30, 30', 30")
8. The device in accordance with claim 7, wherein the bearing pin (17) is cylindrical or conical with respect to the axis of rotation (2).
9. The device in accordance with one of the claims 1 to 8, wherein the inner pipe (30, 30', 30") is made in one piece or is composed of half-shells.
10. The device in accordance with one of the claims 1 to 9, wherein the inner pipe (30, 30', 30") is fastened with radial screws (33) to the plug pipe (18), an end of which that is opposite the screw head extends into axially extending feed strips (32, 32') on the inside of the inner pipe (30, 30', 30").
11. The device in accordance with one of the claims 1 to 9, wherein positive fitting means are formed in the contact surface between the inner pipe (30, 30', 30") and the plug pipe (18) for creating an axial guidance, the means being preferably a groove and spring.
12. The device in accordance with one of the claims 1 to 8, wherein the inner pipe (30'), based on the cross section, is divided into annular segments (40, 41), every other annular segment (41) of which has undercut longitudinal sides for clamped fastening of adjacent segments (40) and the annular segments (41) with undercut longitudinal sides can be fastened with radial screws (33) on the inner circumference of the jacket pipe (18).
13. The device in accordance with claim 12, wherein the annular segments (41) with undercut longitudinal sides have feed strips (32') on their surface forming the inner circumference of the inner pipe (30').
14. The device in accordance with claim 12 or 13, wherein the passage openings (35) are arranged in the clamped annular segments (40).
15. The device in accordance with one of the claims 1 to 14, wherein the inner pipe (30, 30', 30") is secured against longitudinal movement by an axial stop.
16. The device in accordance with claim 15, wherein the stop is formed by an annular shoulder (31) on the inside of the jacket pipe (9) or plug pipe (18).

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