WO1991006498A1 - Discharge apparatus for a silo - Google Patents

Discharge apparatus for a silo Download PDF

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Publication number
WO1991006498A1
WO1991006498A1 PCT/FI1990/000262 FI9000262W WO9106498A1 WO 1991006498 A1 WO1991006498 A1 WO 1991006498A1 FI 9000262 W FI9000262 W FI 9000262W WO 9106498 A1 WO9106498 A1 WO 9106498A1
Authority
WO
WIPO (PCT)
Prior art keywords
silo
bottom wall
discharge
discharge means
arm
Prior art date
Application number
PCT/FI1990/000262
Other languages
French (fr)
Inventor
Ossi Kilpeläinen
Original Assignee
A. Ahlstrom Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by A. Ahlstrom Corporation filed Critical A. Ahlstrom Corporation
Publication of WO1991006498A1 publication Critical patent/WO1991006498A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
    • B65G65/00—Loading or unloading
    • B65G65/30—Methods or devices for filling or emptying bunkers, hoppers, tanks, or like containers, of interest apart from their use in particular chemical or physical processes or their application in particular machines, e.g. not covered by a single other subclass
    • B65G65/34—Emptying devices
    • B65G65/40—Devices for emptying otherwise than from the top
    • B65G65/48—Devices for emptying otherwise than from the top using other rotating means, e.g. rotating pressure sluices in pneumatic systems
    • B65G65/4809—Devices for emptying otherwise than from the top using other rotating means, e.g. rotating pressure sluices in pneumatic systems rotating about a substantially vertical axis
    • B65G65/4836—Devices for emptying otherwise than from the top using other rotating means, e.g. rotating pressure sluices in pneumatic systems rotating about a substantially vertical axis and moving material over a stationary surface, e.g. sweep arms or wheels

Definitions

  • the present invention relates to an apparatus for discharging fine material such as, for example, fiber pulp, chips or sawdust, from a silo via an opening or openings in the bottom of the silo.
  • Some prior art devices for discharging material from the bottom of a silo employ a screw conveyor rotating about the center axis of the silo and extending radially from the wall of the silo to a discharge opening in the center of the bottom.
  • the screw while rotating, feeds the material to be discharged towards said opening via which the material drops down onto a conveyor disposed under the silo.
  • the rotating movement of the screw can be effected for example, as disclosed in U.S. patent specification no. 3896943, by a hydraulic device provided at the outside end of the screw and connected to a toothed gear outside the silo.
  • a drawback of such of discharge devices is their complicated structure. Further, their energy consumption is high because a tightly-packed layer builds up in front of the screw which prevents the screw from rotating.
  • a screw discharger is not suitable in silos through which the material must flow evenly and fairly fast, for example in process silos.
  • discharge arms have been secured to a drive shaft provided centrally in the silo and the arms move the material to the discharge opening or openings of the silo while the arms rotate.
  • the discharge arms are rotated continuosly in one direction or to and fro by a motor or a hydraulic device.
  • An example of this kind of a device is disclosed in Finnish patent specification no. 47328. If an even and fairly fast flow through the silo is desired the bottom of the silo must have several discharge openings whereby also several screw conveyors with drive means are required for discharging the material falling through the bottom. This involves additional costs.
  • an apparatus for discharging fine material from a silo comprising a first discharge means for displacing the fine material along the first bottom wall of the silo to discharge openings in said bottom wall.
  • the apparatus is characterized in that a second bottom wall and a second discharge means are provided under said first bottom wall of the silo with said second discharge means being disposed to displace the fine material dropping down through the openings of the upper, first bottom wall along the lower bottom wall to an opening therein and being rotatable at a higher speed than the upper discharge means.
  • An embodiment of the apparatus according to the present invention comprises a vertical drive shaft disposed centrally in the silo; and a discharge arm having two ends the center of which arm is journalled eccentrically on the drive shaft and the movement of which arm is guided by means provided at the ends of the arms and by counter surfaces provided in the silo in such a way that the ends of the discharge arm move rotatably and reciprocatingly in the direction of the periphery.
  • a second discharge means is secured to the drive shaft of the first discharge means.
  • a desired number of openings can be made in the bottom wall of a silo and still only one screw is needed for discharging the material dropping down through the bottom wall. Since material is discharged all the time through one opening the speed of the discharger can be substantially lower and its drive motor smaller. Energy is saved and wearing of the bottom of the silo and the discharger is reduced.
  • Fig. 1 is a schematic plan top view a top view of an apparatus according to the invention
  • Fig. 2 is a section along line A - A of Fig. 1.
  • reference numeral 2 indicates a lower portion of a process silo with a cylindrical side wall 4 and a plane-like bottom wall 6 with a plurality of openings 8.
  • a second bottom wall 10 is provided under the bottom wall 6.
  • a vertical drive shaft 12 which is provided centrally in the silo, rotated by a drive means 11 and rotatably journalled and sealed by a method known per se, passes through the bottom walls 6 and 10.
  • An eccentric disc 14 is fixed at the end of the drive shaft and a discharge arm 16 having two ends is mounted in bearings to the disc in the immediate vicinity of the bottom wall 6.
  • a second discharge arm 18 with two ends or a doctor is located in the immediate vicinity of the lower bottom wall 10 and is secured to the drive shaft 12.
  • rollers 20 journalled on the arm and in the bottom portion of the silo by the side wall 4, pins 22 are provided in a circle at even spacing the dimension of the spaces corresponding to the diameter of the rollers.
  • the center 23 of the discharge arm 16 which is eccentrically journalled, moves along a circular path around the center axis of the silo and the rollers at the ends of the discharge arm move alternatingly outwards from between the pins, outside the pins towards the next space between the pins and inwards to the space between the spins substantially along an path resembling an epicycloid, thus forcing the discharge arm 16 to a slow revolving movement along the bottom.
  • the second discharge arm 18 secured to the shaft rotates at a higher velocity than the first discharge arm, i.e. at the rotating speed of the drive shaft.
  • the discharge openings 8 in the bottom wall of the silo are dimensioned and located so as to discharge the material supplied to the silo at an as even rate as possible over the whole cross sectional surface of the silo which ensures a homogenous product, for example, when the silo is used as a bleaching silo.
  • the space between the openings is chosen to leave the distance for which the discharge arm 16 moves the material along the bottom of the silo short, typically only about 1 meter.
  • the lower discharge means 18 while it rotates, transfers the material which has dropped down via discharge openings 8 along the lower bottom wall 10 to an elongate opening 24 in the lower bottom under which a duct or a chute 26 is disposed, and in the chute a screw conveyor 28 for tranporting out the discharged material.
  • There is a level detector 32 in the outer wall 30 of the chute which detector detects the level of the material in the chute and controls the operation of the discharger by stopping the drive means 11 when the upper limit level has been reached and actuates it again when the lower limit level has been reached. Since the upper discharge means must transfer the pressurized material along the bottom for a short distance, only, the torque required is small. The dropping down of the material through the openings loosens the material. The amount of material to be discharged per revolution by the lower discharge means is small, thus the discharge means is lightly loaded.
  • the amount of material to be discharged by half a turn of the eccentric disc is approx. 50 1/approx. 4 seconds.
  • the load of the lower discharger is thus very light.
  • the lower discharge means can be provided with elastic or resilient discharge arms.

Abstract

The invention relates to an apparatus for discharging fine material from a silo (2). The apparatus comprises a first discharge means (16) for displacing the fine material along the first bottom wall (6) of the silo to discharge openings (8) in said bottom wall. A second bottom wall (10) and a second discharge means (18) are provided under said first bottom wall (6) of the silo with said second discharge means being disposed to displace the fine material dropping down through the openings (8) of the upper, first bottom wall (6) along the lower bottom wall (10) to an opening (24) therein and being rotatable at a higher speed than the upper discharge means (16).

Description

DISCHARGE APPARATUS FOR A SILO
Field of invention
The present invention relates to an apparatus for discharging fine material such as, for example, fiber pulp, chips or sawdust, from a silo via an opening or openings in the bottom of the silo.
Prior art
Some prior art devices for discharging material from the bottom of a silo employ a screw conveyor rotating about the center axis of the silo and extending radially from the wall of the silo to a discharge opening in the center of the bottom. The screw, while rotating, feeds the material to be discharged towards said opening via which the material drops down onto a conveyor disposed under the silo. The rotating movement of the screw can be effected for example, as disclosed in U.S. patent specification no. 3896943, by a hydraulic device provided at the outside end of the screw and connected to a toothed gear outside the silo. A drawback of such of discharge devices is their complicated structure. Further, their energy consumption is high because a tightly-packed layer builds up in front of the screw which prevents the screw from rotating. A screw discharger is not suitable in silos through which the material must flow evenly and fairly fast, for example in process silos.
In other known solutions for discharging material from the bottom of a silo, discharge arms have been secured to a drive shaft provided centrally in the silo and the arms move the material to the discharge opening or openings of the silo while the arms rotate. The discharge arms are rotated continuosly in one direction or to and fro by a motor or a hydraulic device. An example of this kind of a device is disclosed in Finnish patent specification no. 47328. If an even and fairly fast flow through the silo is desired the bottom of the silo must have several discharge openings whereby also several screw conveyors with drive means are required for discharging the material falling through the bottom. This involves additional costs.
Disclosure of invention The object of the invention is to avoid or minimize the drawbacks mentioned above.
According to the present invention there is provided an apparatus for discharging fine material from a silo, comprising a first discharge means for displacing the fine material along the first bottom wall of the silo to discharge openings in said bottom wall. The apparatus is characterized in that a second bottom wall and a second discharge means are provided under said first bottom wall of the silo with said second discharge means being disposed to displace the fine material dropping down through the openings of the upper, first bottom wall along the lower bottom wall to an opening therein and being rotatable at a higher speed than the upper discharge means.
An embodiment of the apparatus according to the present invention comprises a vertical drive shaft disposed centrally in the silo; and a discharge arm having two ends the center of which arm is journalled eccentrically on the drive shaft and the movement of which arm is guided by means provided at the ends of the arms and by counter surfaces provided in the silo in such a way that the ends of the discharge arm move rotatably and reciprocatingly in the direction of the periphery. In the embodiment of the present invention applying the above discharging arrangement, a second discharge means is secured to the drive shaft of the first discharge means. In the solution according to the present invention, a desired number of openings can be made in the bottom wall of a silo and still only one screw is needed for discharging the material dropping down through the bottom wall. Since material is discharged all the time through one opening the speed of the discharger can be substantially lower and its drive motor smaller. Energy is saved and wearing of the bottom of the silo and the discharger is reduced.
Brief description of drawing
The invention is described in detail below, by way of example, with reference to the accompanying drawings in which:
Fig. 1 is a schematic plan top view a top view of an apparatus according to the invention; and Fig. 2 is a section along line A - A of Fig. 1.
In the figures, which illustrate a preferred embodiment of the apparatus according to the invention, reference numeral 2 indicates a lower portion of a process silo with a cylindrical side wall 4 and a plane-like bottom wall 6 with a plurality of openings 8. A second bottom wall 10 is provided under the bottom wall 6.
A vertical drive shaft 12 which is provided centrally in the silo, rotated by a drive means 11 and rotatably journalled and sealed by a method known per se, passes through the bottom walls 6 and 10. An eccentric disc 14 is fixed at the end of the drive shaft and a discharge arm 16 having two ends is mounted in bearings to the disc in the immediate vicinity of the bottom wall 6. A second discharge arm 18 with two ends or a doctor is located in the immediate vicinity of the lower bottom wall 10 and is secured to the drive shaft 12.
At both ends of the discharge arm 16, there are rollers 20 journalled on the arm and in the bottom portion of the silo by the side wall 4, pins 22 are provided in a circle at even spacing the dimension of the spaces corresponding to the diameter of the rollers. While the drive shaft 12 rotates, the center 23 of the discharge arm 16 which is eccentrically journalled, moves along a circular path around the center axis of the silo and the rollers at the ends of the discharge arm move alternatingly outwards from between the pins, outside the pins towards the next space between the pins and inwards to the space between the spins substantially along an path resembling an epicycloid, thus forcing the discharge arm 16 to a slow revolving movement along the bottom. While the drive shaft rotates, the second discharge arm 18 secured to the shaft rotates at a higher velocity than the first discharge arm, i.e. at the rotating speed of the drive shaft.
The discharge openings 8 in the bottom wall of the silo are dimensioned and located so as to discharge the material supplied to the silo at an as even rate as possible over the whole cross sectional surface of the silo which ensures a homogenous product, for example, when the silo is used as a bleaching silo. The space between the openings is chosen to leave the distance for which the discharge arm 16 moves the material along the bottom of the silo short, typically only about 1 meter.
The lower discharge means 18, while it rotates, transfers the material which has dropped down via discharge openings 8 along the lower bottom wall 10 to an elongate opening 24 in the lower bottom under which a duct or a chute 26 is disposed, and in the chute a screw conveyor 28 for tranporting out the discharged material. There is a level detector 32 in the outer wall 30 of the chute which detector detects the level of the material in the chute and controls the operation of the discharger by stopping the drive means 11 when the upper limit level has been reached and actuates it again when the lower limit level has been reached. Since the upper discharge means must transfer the pressurized material along the bottom for a short distance, only, the torque required is small. The dropping down of the material through the openings loosens the material. The amount of material to be discharged per revolution by the lower discharge means is small, thus the discharge means is lightly loaded.
Example
Number of revolutions of the upper discharge means 0,1 r/min
Number of revolutions of the lower discharge means 7 r/min Capacity 40 m3/h
The amount of material to be discharged by half a turn of the eccentric disc is approx. 50 1/approx. 4 seconds. The load of the lower discharger is thus very light.
The invention is of course not limited to the embodiment presented above but it can be modified within the scope of protection defined by the patent claims. Thus for example the lower discharge means can be provided with elastic or resilient discharge arms.

Claims

We claim:
1. An apparatus for discharging fine material from a silo (2), comprising a first discharge means (16) for displacing the fine material along the first bottom wall (6) of the silo to discharge openings (8) in said bottom wall, characterized in that a second bottom wall (10) and a second discharge means (18) are provided under said first bottom wall (6) of the silo with said second discharge means being disposed to displace the fine material dropping down through the openings (8) of the upper, first bottom wall along the lower bottom wall to an opening (24) therein and being rotatable at a higher speed than the upper discharge means (16).
2. An apparatus according to claim 1 for discharging material from a silo, the apparatus comprising a vertical drive shaft (12) disposed centrally in the silo; and a discharge arm (16) with two ends and with the center (23) of which arm is eccentrically journalled on the drive shaft and the movement of which is guided by means (20) at the ends of the arm and by counter surfaces (22) provided in the silo in such a way that the ends of the discharge arm move alternatingly or rotate with axial reciprocation in the direction of the periphery, characterized in that the second discharge means (18) disposed under the first bottom wall (6) of the silo is secured to the drive shaft (12) of the first discharger (16).
3. An apparatus according to claim 2, characterized in that the lower discharge means (18) is provided with flexible discharge arms.
4. An apparatus according to claim 3, characterized in that the discharge arms of the lower discharge means (18) are resiliently or elastically joined to the hub of the discharge means.
5. An apparatus according to any of claims 1 - 4, characterized in that there is a duct or chute (26) under the opening (24) in the lower, second bottom wall (10), and a screw conveyor (28) disposed in said duct or chute.
6. An apparatus according to claim 5, characterized in that a detector (32) for detecting or sensing the level of the fine material is disposed in the duct or chute (26).
PCT/FI1990/000262 1989-11-01 1990-11-01 Discharge apparatus for a silo WO1991006498A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI895174A FI895174A0 (en) 1989-11-01 1989-11-01 UTMATNINGSANORDNING FOER SILO.
FI895174 1989-11-01

Publications (1)

Publication Number Publication Date
WO1991006498A1 true WO1991006498A1 (en) 1991-05-16

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1990/000262 WO1991006498A1 (en) 1989-11-01 1990-11-01 Discharge apparatus for a silo

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WO (1) WO1991006498A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0697357A1 (en) * 1994-08-15 1996-02-21 Bühler Ag Micro-metering device
CN113941218A (en) * 2020-07-15 2022-01-18 中冶长天国际工程有限责任公司 Adsorption tower flue gas leakage-prevention control system, method and device

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1104434B (en) * 1958-03-25 1961-04-06 Fellner & Ziegler G M B H Bunker discharge device
GB974446A (en) * 1962-10-16 1964-11-04 Novadel Ltd Improvements in apparatus for feeding powdered material
DE2461696A1 (en) * 1974-12-27 1976-07-08 Polysius Ag Vertical regulator for powder flow - has direct vertical feed with few working and wearing parts
EP0247682A1 (en) * 1986-05-23 1987-12-02 A. Wijnveen B.V. Outlet device for a container for bulk material
DE3727233A1 (en) * 1987-08-14 1989-02-23 Siemens Ag Bulk-material feed and gas removal device, in particular for counterflow moving-bed filters
WO1989010320A1 (en) * 1988-04-25 1989-11-02 A. Ahlstrom Corporation Discharge apparatus for a silo

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1104434B (en) * 1958-03-25 1961-04-06 Fellner & Ziegler G M B H Bunker discharge device
GB974446A (en) * 1962-10-16 1964-11-04 Novadel Ltd Improvements in apparatus for feeding powdered material
DE2461696A1 (en) * 1974-12-27 1976-07-08 Polysius Ag Vertical regulator for powder flow - has direct vertical feed with few working and wearing parts
EP0247682A1 (en) * 1986-05-23 1987-12-02 A. Wijnveen B.V. Outlet device for a container for bulk material
DE3727233A1 (en) * 1987-08-14 1989-02-23 Siemens Ag Bulk-material feed and gas removal device, in particular for counterflow moving-bed filters
WO1989010320A1 (en) * 1988-04-25 1989-11-02 A. Ahlstrom Corporation Discharge apparatus for a silo

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, Vol. 10, No. 216, M502; & JP,A,61 055 025, 19-03-1986, (YOSHIO YAMAMOTO). *
PATENT ABSTRACTS OF JAPAN, Vol. 7, No. 137, M222; & JP,A,58 052 122, 28-03-1983, (SHOWA DENKO K.K.). *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0697357A1 (en) * 1994-08-15 1996-02-21 Bühler Ag Micro-metering device
CN113941218A (en) * 2020-07-15 2022-01-18 中冶长天国际工程有限责任公司 Adsorption tower flue gas leakage-prevention control system, method and device
CN113941218B (en) * 2020-07-15 2023-09-29 中冶长天国际工程有限责任公司 Adsorption tower flue gas leakage prevention control system, method and device

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Publication number Publication date
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