Screw filter press

Abstract

A screw filter press comprising a screw shaft, having at least one coil turn and two screw shaft ends. The shaft axis is parallel to the gravity vector and is supported by screw shaft upper end connected to a rotary drive. The screw shaft is enclosed a filter area by a cylindrical filter tube, with openings and which is adjacent radially to a filtrate space, to which underpressure is applied. The sliding tube radially surrounding the screw shaft is the same inner diameter as the filter tube. Radial play occurs between at last one coil turn adjoining the filter tube proximate to the filter tube inner wall.

Claims

1. A screw filter press comprising: a screw shaft including at least one coil turn and two screw shaft ends for driving a filtrate containing a suspension of solids upward upon rotation, a shaft axis of the screw shaft oriented parallel to a gravity vector and which is supported on one side via an upper screw shaft end which is connected to a rotary drive and which is enclosed coaxially, at least in a lower partial filter area, by a cylindrical filter tube, with openings and at which a filtrate space radially adjoins, to which underpressure is applied by an external source of underpressure below atmospheric pressure; and a sliding tube, radially surrounding the screw shaft in a fluid-tight manner coaxial to the filter tube with an inner diameter equal to an inner diameter of the filter tube; and wherein the sliding tube includes a discharge opening for solid filtrate at the upper screw shaft end, the equal inner diameter of the sliding tube and the filter tube causing the filtrate to flow during operation of the press, discharge of the solid filtrate with a controllable consistency, and the at least one coil turn of the screw shaft ending radially relative to the screw shaft in a flange which revolves helically around the screw shaft and which adjoins the filter tube at an inner wall thereof; the underpressure below atmospheric pressure from the external source is applied to liquid filtrate in the filtrate space for drawing liquid from the liquid filtrate in the filtrate space in a start-up phase and after the start-up phase drawing liquid from the filtrate in a sliding area of the sliding tube.

2. The screw filter press comprising: A screw shaft including at least one coil turn and two screw shaft ends for driving a filtrate containing a suspension of solids upward upon rotation, a shaft axis of the screw shaft oriented parallel to a gravity vector and which is supported on one side via an upper screw shaft end which is connected to a rotary drive and which is enclosed coaxially, at least in a lower partial filter area, by a cylindrical filter tube, with openings and at which a filtrate space radially adjoins, to which underpressure is applied by an external source of underpressure below atmospheric pressure; and a sliding tube, radially surrounding the screw shaft in a fluid-tight manner coaxial to the filter tube with an inner diameter equal to an inner diameter of the filter tube; and wherein the sliding tube includes a discharge opening for solid filtrate at the upper screw shaft end, the equal inner diameter of the sliding tube and the filter tube causing the filtrate to flow during operation of the press, discharge of the solid filtrate with a controllable consistency, and the at least one coil turn of the screw shaft ending radially relative to the screw shaft in a flange which revolves helically around the screw shaft and which adjoins the filter tube at an inner wall thereof; the underpressure below atmospheric pressure from the external source is applied to liquid filtrate in the filtrate space for drawing liquid from the liquid filtrate in the filtrate space in a start-up phase and after the start-up phase drawing liquid from the filtrate in a sliding area of the sliding tube; and the sliding tub has a length which in the start-up phase causes the liquid in the liquid filtrate to be drawn from the filtrate space to form the solid filtrate in the sliding area which blocks the flow of air to the discharge opening.

3. The screw filter press according to claim 2, comprising: an elastic wiping lip along the flange of the at least one coil turn in the filter area which adjoins the filter tube with a prestress at an inner wall.

4. The screw filter press according to claim 3, wherein: the elastic wiping lip is an elastic abrasion-resistant material; and the elastic wiping lip has a width of from 1-3 mm. and a height from 2-5 mm. which is elevated relative to the flange.

5. The screw filter press according to claim 3, wherein: the elastic wiping lip is polyurethane.

6. The screw filter press according to claim 3, wherein: the elastic wiping lip is prefabricated and glued into a groove extending along the flange.

7. The screw filter press according to claim 2, comprising: radial play between the at least one coil turn of the screw shaft and the sliding tube.

8. The screw filter press according to claim 7, wherein: the radial play between the at least one coil turn of the screw shaft and the sliding tube is between 0.1 and 0.3 mm.

9. The screw filter press according to claim 3, wherein: speed of rotation of the rotary drive and underpressure in the filtrate space are regulated.

10. The screw filter press according to claim 2, comprising: axial or spiral conveying grooves are disposed in an inner wall of the sliding tube.

11. The screw filter press according to claim 6, comprising: axial or spiral conveying grooves are disposed in an inner wall of the sliding tube.

12. The screw filter press according to claim 2, wherein: the screw shaft encompasses an odd number of coil turns.

13. The screw filter press according to claim 6, wherein: the at least one coil turn encompasses a pitch angle ranging between 30-50, wherein the pitch angle is enclosed by a shaft axis and a coil turn.

14. The screw filter press according to claim 6, wherein: the sliding tube has a tube length half of a length of the filter tube.

15. The screw filter press according to claim 9, wherein: the sliding tube has a tube length half of a length of the filter tube.

16. The screw filter press according to claim 2, comprising: a lower screw shaft end ending at a supply line; and the filter tube is attached in a fluid tight manner to the supply line.

17. The screw filter press according to claim 2, wherein: the at least one coil turn of the screw shaft with a filter and the sliding tube encloses a conveying space helically surrounding the screw shaft; and the conveying space is larger in cross sectional area at the filter tube than at the sliding area.

18. The screw filter press according to claim 6, wherein: the at least one coil turn of the screw shaft with a filter and the sliding tube encloses a conveying space helically surrounding the screw shaft; and the conveying space is larger in cross sectional area at the filter tube than at the sliding area.

19. The screw filter press according to claim 9, wherein: the at least one coil turn of the screw shaft with a filter and the sliding tube encloses a conveying space helically surrounding the screw shaft; and the conveying space is larger in cross sectional area at the filter tube than at the sliding area.

20. The screw filter press according to claim 13, wherein: the at least one coil turn of the screw shaft with a filter and the sliding tube encloses a conveying space helically surrounding the screw shaft; and the conveying space is larger in cross sectional area at the filter tube than at the sliding area.

21. The screw filter press according to claim 16, wherein: the at least one coil turn of the screw shaft with a filter and the sliding tube encloses a conveying space helically surrounding the screw shaft; and the conveying space is larger in cross sectional area at the filter tube than at the sliding area.

22. The screw filter press according to claim 16, wherein: a cross section of a conveyor space tapers continuously with increasing distance from the lower screw shaft end.

23. The screw filter press of claim 2 comprising: a housing comprising a lower part and an upper part wherein in the lower part of the housing the filter tube is disposed coaxially to the screw shaft and the filtrate space is located between the filter tube and an inner wall of the housing; and a pipe coupled to the lower part of the housing for connection to the external source of the underpressure below atmospheric pressure for drawing liquid from the filtrate space and from a solid cake.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be described in an exemplary manner below by means of exemplary embodiments with reference to the drawings without limiting the general idea of the invention.

(2) FIG. 1 shows a longitudinal section through a screw filter press according to the invention, which stands upright;

(3) FIG. 2a shows a flange embodiment of the coils in the filter area in cross section along section A-A in FIG. 1;

(4) FIG. 2b shows an alternative flange embodiment of the coils in the filter area along section A-A in FIG. 1;

(5) FIG. 2c shows a further alternative flange embodiment of the coils in the filter area provided with the screw shaft being polyurethane, called cell vulcollan, along section A-A in FIG. 1;

(6) FIG. 2d shows the flange embodiment of the coils and of the conveying grooves in the sliding area along section B-B in FIG. 1;

(7) FIG. 3 shows an attachment comprising four screw filter presses, which are connected in series and connected to a tube bank; and

(8) FIGS. 4a-c show sectional views through the screw coils in different axial layers along the screw coil.

DETAILED DESCRIPTION OF THE INVENTION

(9) A drivable screw shaft 10 standing upright, that is, parallel to the acting gravity, is coaxially arranged in an upright housing 1 comprising a center axis 2.

(10) The housing, which is arranged to be upright, has a plurality of parts, wherein the individual parts are connected to one another via flanges. The lower part 24 of the housing encompasses a larger outer diameter than the upper part 28 of the housing, which is flange-mounted thereon. In the lower housing part 24, the filter tube 3 is arranged coaxially to the screw shaft 10. The filtrate space 5 is located between filter tube 3 and housing inner wall 6.

(11) The lower housing part 24, in which the filter tube 3 is held between the upper and lower housing flanges 8, 9, where the filtrate drains through the filter tube, will also be referred hereinbelow as filter area F. The upper flange 8 is embodied as fixed bearing for holding the filter tube, while the housing flange 9 only prevents a radial displacement of the filter tube 3.

(12) If necessary, the filter tube 3 has openings ranging from 0.05 to 1 mm, so that the liquid of the suspension can drain through the openings of the filter tube 3 into the filtrate space 5 between housing inner wall 6 and filter tube outer wall 7.

(13) The filter tube 3 can be a perforated plate, wherein the through holes are open towards the housing inner wall 6. The filter tube 3, however, can also be a cylindrical disk filter with openings which also open towards the housing inner wall 6, thus opening conically or in a funnel toward the housing inner wall. This embodiment of the hole has the advantage that the holes themselves virtually do not clog.

(14) The filtrate space 5, which is formed between housing inner wall 6 and filter tube outer wall 7 is defined upwards by the flange 8, which is connected to the housing 1 and which is embodied as described.

(15) The filtrate space 5 is defined downwardly by the housing flange 9, in which the filter tube 3 is supported such that it cannot displace radially. Above the housing flange 9, a filtrate drain nozzle 11, through which the liquid of the suspension drains from the filtrate space 5 or is pumped off, is attached laterally.

(16) In terms of this description, a suspension is understood to be a suspension of finely distributed solid matter in a liquid, such as it is present in so-called slurry or so-called manure, e.g.

(17) The filtrate drain valve 11 can be closed by a valve 12, such as a ball valve.

(18) A sliding tube 4 is attached with its lower tube flange 13 onto the flange 8, which defines the filtrate space 5 upwardly towards the drive motor/rotary drive 15 located on the top, and is connected to the flange 8, by screws.

(19) The longitudinal axis of the attached sliding tube 4 and the longitudinal axis of the screw shaft 10 are congruent with the center axis 2. The inner diameter of the filter tube 3 and the inner diameter of the sliding tube 4 are also equal so that the filter area F and the sliding area G have the same inner diameter.

(20) The upper part of the housing 28 is defined upwardly by means of a plate 18. The discharge opening 20 for the solid matter of the suspension is located below the plate 18. The coils 14 of the screw shaft 10 end at a distance to the plate 18. The screw shaft 10 itself, which encompasses a collar 30 at the end, is guided up to the drive shaft of the drive motor 15, by an electric motor, and is connected thereto in a rotary manner, by a hub 19, which supports the coupling 17 at the lower end.

(21) The screw shaft 10 preferably encompasses two or more coils 14. An odd number of coils is particularly advantageous. A number of five has proven to be particularly advantageous in tests. It goes without saying that the number of coils depends on the diameter of the screw shaft. The diameter was 75 mm in tests.

(22) In the exemplary embodiment, the screw shaft 10 thus has five coils 14 with a diameter of 75 mm comprising a coil pitch of preferably 45. The coil pitch should preferably be in a range of from 30 to 50.

(23) The screw shaft 10 is driven via a drive motor 15. The drive motor 15 is connected to the screw shaft in peripheral direction via a coupling 17, such as a claw coupling (not illustrated in detail).

(24) The attachment of the drive motor 15 takes place on the support plate 16, which is also located on top by screw bolts. The support plate is attached to the housing 1, which stands upright, above the support of the screw shaft.

(25) The support of the screw shaft, which accommodates axial as well as radial forces, is integrated into the plate 18 of the upper housing part.

(26) The support plate 16, to the upper side of which the motor 15 is attached, encompasses a distance to the plate 18, which is used to connect or couple the screw shaft to the motor.

(27) A discharge opening 20 is arranged at the upper end of the upper housing part. A chute 21, on which the solid matter is conveyed to the discharge openings, glides into a catch basin (not illustrated), and is connected to the discharge opening.

(28) The supply of the suspension takes place via a housing nozzle 22, which is flange-mounted to the housing flange 9 of the lower housing.

(29) The housing nozzle is molded such that the screw shaft 10 reaches approximately into the center of the tube-shaped supply line 23 or tube bank 40, through the part, which is directly connected to the lower housing as shown in FIG. 3. In the area of the supply, the supply line 23 together with the housing nozzle is a one-piece part, to which the supply line parts are welded or flange-mounted (not illustrated).

(30) In the event that a screw filter press is used, the one side of the housing nozzle serves as connection to the supply line and the side located opposite thereto serves to couple the tube into a level-maintaining catch basin 25, which ensures the adherence to the maximum and minimum level in the housing of the screw filter press by means of level regulators. The inflow line to the catch basin is connected to the housing nozzle coaxially in the horizontal direction and encompasses a shut-off valve 29 or a drain opening for the supply line. Located opposite thereto, is the inlet of a flushing tube 31 as shown in FIG. 3.

(31) In the event that a plurality of screw filter presses are arranged in series, the horizontal sides of the housing nozzles are connected to in a tube bank 40 by welding and the screw filter presses are flange-mounted to the vertical connections (see, in particular FIG. 3). A level regulation is arranged herein as in the case of an individual screw filter press, which must be dimensioned accordingly. Provision is also made for a flushing tube 31 and a shut-off valve 29. The supply of the suspension takes place via the nozzle 35.

(32) Due to the level regulation, a flow is created in the supply line or in the tube bank which ensures that the suspension is always mixed evenly. However, larger foreign particles, which are significantly heavier, remain in the lower part of the supply line or in the tube bank.

(33) Due to the fact that the screw shaft only reaches approximately into the center of the supply line or the tube bank, coarse solid matter can deposit at the bottom of the supply line and does not reach into the area of the screw shaft. The deposits can be removed from time to time by means of the flushing tube 31 via the shut-off valve 29.

(34) If necessary, the screw shaft 10 is driven by an electric, pneumatic or hydraulic speed-controlled motor. The speed lies in the operating range from 30 to 100 rpm.

(35) On the drive side, a secondary transmission or a stepped transmission can be provided for reaching the speed. A gear motor can also be used. A claw coupling is used as coupling or if necessary, an adjustable overload coupling.

(36) The filter tube 3 is made of metal and the holes are carved by laser methods, for example, in the desired shape, generally with a larger hole cross section towards the housing inner side 6.

(37) A cylindrical disk filter can also be used instead of a filter tube. The screw shaft is only supported on one side on the top in the support plate and does not get damaged in response to making contact with the filter tube. The screw shaft or the coils thereof are made of plastic.

(38) In the vertical direction, the screw filter press, which stands upright, can roughly be divided into two areas, which must substantially fulfill two different objects.

(39) The lower housing comprising the cylindrical filter tube can be identified as filter area and the upper housing area up into the level of the discharge opening can be identified as sliding area G. The filter area F is approximately twice as high as the sliding area G.

(40) The rotating screw shaft 10 conveys the suspension out of the supply line 23 or the tube bank 40 and the suspension moves upwards along the coils. The liquid is hereby separated from the solid matter. That is, the liquid drains into the filtrate space through the openings of the filter tube 3. The rotation of the screw shaft thus also causes solid matter to be hurled against the inner wall of the filter tube.

(41) The flanges of the coils must in this area keep the inner wall of the filter tube free. This takes place by the flanges scraping the solid matter, so that the solid matter is further conveyed to the discharge opening, and the solid matter forms a solid cake by removing liquid.

(42) With an increase in dehumidification, the solid cake tends to settle on the coil. In the sliding area, in which a solid cake has already formed, the slidability of the solid cake is most important and a further high dehumidification can even cause the solid cake to clump.

(43) The screw shaft in the sliding area thus has the sole object of conveying and it fulfills this task, provision is made for a play 5 between 0.1 and 0.3 mm the inner wall of the sliding tube and the outer flange of the coils, so that the coils of the screw shaft do not abut on the inner space of the sliding tube in the sliding area as shown in FIG. 2d.

(44) In the filter area, however, the coil flanges remove the solids from the inner side of the filter tube 3, so that the drainage of the liquid is not impeded.

(45) FIGS. 2a-c show three different possibilities for embodying the elastic elements 38 at the coil flanges. FIG. 2a shows the insertion of a strip 32 into a groove 33. The strip is an abrasion-resistant and elastic material, such as polyurethane.

(46) Another possibility for embodying the flanges is shown in FIG. 2b. The flanges of the coils are turned here as well and a profile is attached to the flange surface, either into a groove, or is adhered to the planar surface. The profile of the flange pointing towards the filter tube, for example, encompasses an attachment 34, which is approximately 2 mm wide and 3 mm high. The profile, like the strip, is the elastic, abrasion-resistant polyurethane.

(47) FIG. 2c shows an attachment 34 to the coils as in FIG. 2b. In the case of the screw shaft illustrated in FIG. 2c, the entire screw coil is made of polyurethane (called vulcollan) or at least the part of the screw coil in the filter area is made of polyurethane. In the sliding area a play of from 0.1-0.3 mm exists between coil flange and inner surface of the sliding tube in the event that the entire screw shaft is made of polyurethane.

(48) The embodiment of the flange coils in the filter area in the case of the described alternatives is always the same in dimension. For instance, the width of the flanges lies between 1-3 mm; the height lies between 2-5 mm.

(49) The mentioned material is vulcollan, which is a polyurethane, which is foamed with water, which has highly-dynamic characteristics. Cellular vulcollan allows for approx. 80% compression in response to small cross expansion and a minimal remaining deformation. See form list edition 1992 of Paul Pleiger, Maschinenfabrik GmbH+Co.KG, Im Hammertal 51, 58456 Witten 3.

(50) Due to these physical characteristics, the screw shaft 10 is inserted into the filter tube 3 in the filter area under slight prestress. It has thus proven to be particularly advantageous for the installation to use an odd number of coils, e.g. 3, 5, 7.

(51) As was already described, the solid matter is conveyed upwards to the discharge opening 20 by the coils 14. A solid cake forms thereby, which becomes increasingly solid with increasing travel upwards.

(52) To accelerate the formation of the solid matter cake, the underpressure, which is created by draining the filtrate, is regulated via the connection 26 via a valve 36. In response to a constant underpressure of approx. 0.5 bar, which is set at the valve 36 from an external source of underpressure below atmospheric pressure 42 and which acts on the suspension, liquid is not only removed from the suspension to a higher extent, but liquid is also removed from the solid cake in the sliding area.

(53) A constant underpressure below atmospheric pressure (e.g. 0.5 bar) has only been reached after the start-up phase when a solid cake has formed in the sliding tube 4, so that the air inflow from the area of the discharge opening 20 is reduced, even almost eliminated.

(54) Due to the removal of liquid, the solid cake often tends to form clumps. This can lead to the clogging of the individual coils.

(55) The sliding tube for conveying grooves 27 prevents the formation of clumps and provides a firm link of the solid cake to the coils, in particular the coil base. See FIG. 2d.

(56) In the exemplary embodiment, eight conveying grooves 27 are in longitudinal direction. These conveying grooves counteract the clogging of the coils and increase the solid matter discharge. They can also be embodied in a spiral-shaped or helical manner instead of as upright conveying grooves.

(57) FIG. 3 shows a filter arrangement comprising four screw filter presses, which are connected in series.

(58) The suspension is supplied to the four screw filter presses via a supply line 23 in a tube bank 40. In the event that the four screw filter presses cannot drain the quantity, which is supplied by a pump, the excess is pumped into the catch basin 25. This catch basin is equipped with a level regulation, so that a maximum level and a minimum level are defined.

(59) The suspension is always in motion in the tube bank by this level regulation. On the one hand, it flows towards the catch basin, on the other hand, it flows from the catch basin back to the supply line so that the suspension is thus always mixed.

(60) The maximum level reaches approximately into the lower half of the sliding tube 4. The minimum level lies in the lower area of the filter tube. Due to the fact that the screw shaft 10 accommodates suspensions only from the upper half of the supply line 23, it is ensured that larger solid matter, which can lead to damages, cannot reach the coils.

(61) In the event that solid matter should accumulate in the supply line or the tube bank over time, they can be removed via the shut-off valve 29, which is connected to the inlet.

(62) The suspension is guided upwards along the coils, wherein the speed of the screw shaft is increased or reduced, depending on the solid matter content, and/or the underpressure is increased. The speed and the underpressure are always changed such that the desired consistency is reached in the solid cake.

(63) On its way upwards, the separation of solid matter and liquid is carried out to the provided extent. When the solid matter has reached the discharge opening 20, it is discharged and the liquid is pumped off via the filtrate drain nozzle 11.

(64) The coils of the screw shaft 10 preferably encompass a pitch of between 30 and 50. A pitch of 45 has proven to be particularly advantageous.

(65) In the event that a suspension comprising approx. 3% of solid matter content is supplied via the housing nozzle 22 in the case of a screw filter press as illustrated in FIG. 1, the suspension is guided upwards along the coil turns. The liquid of the suspension is filtered through the filter tube 3 and reaches into the filtrate space 5. The filtrate drains from there or it is pumped off.

(66) At the onset of the supply of the suspension, the screw shaft 10 is made to rotate at approx. 50 to 60 rpm by means of the drive motor 15 so that the coil turn and the direction of rotation of the motor are oriented in the same direction, provided that a reverse gear is not connected in-between.

(67) The grooves between the coils are such that the coils of the screw shaft initially press the solid matter against the filter tube over and over and subsequently against the tube inner wall of the tube 4, and attempt to convey the solid matter towards the discharge. It is thus important that the embodiment of the groove spaces between the coils accumulates solid matter and the dwell time of the solid matter in the coils of the screw shaft can be adapted to the requirements, which is why a speed was chosen in a low range of approx. 50 rpm or why the underpressure is intensified. The type of suspension must be considered in response to the selection of the screw shaft as well.

(68) In a test facility, the screw shaft had five coils in response to a total diameter of the screw shaft of 75 mm. The filter tube had a hole size of 0.1 mm. The height of the filter area F, from housing flange 9 to flange 8 was 200 mm. The height of the sliding area G was approx. 100 mm. The screw shaft was rotated at approx. 50 rpm. The ejected solid matter pellets had a moisture content of approx. 75%. The underpressure in the filtrate space was approx. 0.4 bar.

(69) The diameter of the coaxially arranged cylindrical sliding tube 4 and of the filter tube 3 was 75 mm. The conveyor groove depth was approx. 1 mm, a width of 3 mm and 8 conveyor grooves 8 were arranged at the periphery.

(70) Such screw filter presses are used for separating solid matter and liquid in suspensions. Such suspensions, which are often called solid matter suspensions, can be found in response to the fermenter slurry processing from biogas plants, for example, in slurry processing, in sewage sludge disposal, in vegetable oil pressing systems, in fruit juice production, in the recovery of recyclable material for process liquids, and in waste water cleaning and others.

(71) To optimize the dehumidification, it may be necessary for the degree of dehumidification of the solid material pellets to be measured continuously or at certain intervals and for the speed of the screw shaft, for example, in the underpressure in the filtrate space to be regulated. The underpressure can be changed via a speed change of the exhaust pump or via an air inlet valve. This can be carried out manually or also via automatic regulations.

(72) A further measure for improving the degree of dehumidification can be obtained from an exemplary embodiment as is illustrated in FIGS. 4a, b and c. FIGS. 4a to c in each case show radial sectional views through the screw shaft 10, in different axial positions relative to the screw shaft 10. FIG. 4a shows a section through the screw shaft 10 in the sliding area, in which the screw shaft 10 is surrounded by the sliding tube 4. The sliding tube 4 with the screw shaft 10 encloses a conveying space 41 along the coil turns, which helically surround the screw shaft 10. The filter tube 3 with the screw shaft 10 in each case encloses a conveying space 41 in the filter area as shown in FIGS. 4b and 4c. It is noted at this point that the radial section shown in FIG. 4b is located in the upper area along the filter area. FIG. 4c shows the screw shaft end which is surrounded by the filter tube 3 in axial viewing direction. It is important that the cross section of the conveying space 41 decreases from the lower screw shaft end in the direction of the upper screw shaft end. The condensing effect for the goods, which are to be conveyed upwards by the screw shaft, increases towards the top. A screw shaft designed in this manner is mainly suitable for drying or draining of suspensions, which contain easily compressible solid matter contents.

LIST OF REFERENCE NUMERALS

(73) 1 housing 2 center axis 3 filter tube 4 sliding tube 5 filtrate space 6 housing inner wall 7 filter tube outer wall 8 flange 9 housing flange 10 screw shaft 11 filtrate drain nozzle 12 valve 13 tube flange 14 coil/coil turn 15 drive motor/rotary drive 16 support plate 17 coupling 18 plate 19 hub 20 discharge opening 21 chute 22 housing nozzle 23 supply line 24 lower part of the housing 25 catch basin 26 connection 27 conveying grooves 28 upper part of the housing 29 shut-off valve 30 collar 31 flushing tube 32 strip 33 groove 34 attachment 35 nozzle 36 valve 38 elastic element 40 tube bank 42 source of below atmospheric pressure 41 conveying space F filter area G sliding area S play pitch angle