GB1580653A

GB1580653A - Transportation of fibrous material through a conduit

Info

Publication number: GB1580653A
Application number: GB28561/77A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-07-07
Filing date: 1977-07-07
Publication date: 1980-12-03
Also published as: SE7607754L; SE423376B; FR2357451A1; DE2730765A1; FI772121A; FR2357451B1

Description

(54) TRANSPORTATION OF FIBROUS MATERIAL THROUGH A CONDUIT (71) We, STANLEY OLSSON, of Swedish nationality, of Kampastigen 4, S- 352 52 Växjö, Sweden, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to the transportation of fibrous material. More particularly the invention relates to the transportation of fibrous material through a conduit, the fibrous material being carried through the conduit by a flow of air. The fibres may for example be fibres of pulp and may be supplied to the conduit from a fibreproducing machine or a fibre-processing machine.

For transporting fibres of pulp or cellulose fibres it is known to use belt conveyors, the belts of which are provided with buckets, fingers or driving means of different kinds. It is also known to use worm conveyors for this purpose. Finally, by means of a blower, fibres could be blown in a conduit from one processing machine to another.

Such methods have led to difficulties of different kinds especially when controllable conditions are desired.

When using belt conveyors or worm conveyors great difficulties have arisen because of the fact that the fibres conveyed have a tendency to adhere to each other and form lumps as soon as the concentration of fibres is high. Furthermore, the fibres have a troublesome tendency to adhere to the driving means, buckets or feed screws so that cleaning is required after a certain period of operation in order to reestablish the intended function.

When blowing the fibres in a conduit by means of a blower the problems mentioned above are not present if the blower is of a self-cleaning type and if the conduit system is correctly designed. However, this method of conveying has heretofore suffered from considerable drawbacks due to the fact that the mixture of fibres and air discharged from the conduit and fed to a processing machine has a quite uncontrollable content of fibres and that the discharge must be carried out at a superatmospheric pressure when a cyclone is used. Consequently the rate of discharge is very difficult to control.

An object of the present invention is to provide a method of transporting fibrous material through a conduit by means of a flow of air and separating the fibrous material from the flow of air in a separator, the pressure in the separator being substantially equal to that exterior to the separator, the concentration of the fibrous material in the flow of air being controllable and the rate of discharge of the fibrous material from the separator being controllable. A further object of the invention is to provide apparatus for carrying out the method.

In accordance with the present invention there is provided a method of transporting fibrous material, comprising: providing a flow of air passing along a conduit and introducing the fibrous material into the conduit so that it is carried along the conduit by the flow of air, the flow of air passing from the conduit into a separator; maintaining the air pressure in the separator substantially equal to the air pressure exterior to the separator and controlling the air flow conditions in the separator to establish within the separator a first or separating zone through which at least part of the flow of air passes and a second or discharge zone in which the air is substantially static, at least part of the fibrous material separating from the flow of air in the separating zone and falling into the discharge zone without experiencing agglomeration; when the discharge zone is open to the exterior of the separator, the fibrous material being discharged from the separator without experiencing agglomera tion by being allowed to fall from the discharge zone to the exterior of the separator; and maintaining the concentration of fibrous material in the flow of air at a predetermined point substantially constant.

Preferably air is allowed to escape from the conduit at a point upstream of the separator.

In accordance with the present invention, there is further provided apparatus for carrying out the method of the invention, the apparatus comprising: a conduit; a fan or blower arranged for providing a flow of air along the conduit; means for introducing fibrous material into the conduit in order for the fibrous material to be carried along the conduit by the flow of air; a separator to which the conduit leads; means for maintaining the air pressure in the separator substantially equal to the pressure exterior to the separator and means for controlling air flow conditions in the separator to establish within the separator a first or separating zone through which at least part of the flow of air passes and a second or discharge zone in which the air is substantially static, the fibrous material being able to fall from the separating zone into the discharge zone; means for allowing separated fibrous material to fall from the discharge zone to the exterior of the separator; and means for measuring the concentration of fibrous material in the flow of air at a predetermined point and controlling the rate of introduction of fibrous material into the flow of air to maintain the concentration of fibrous material in the flow of air at the predetermined point substantially constant.

Preferably the separator is a cyclone separator and the means for controlling air flow conditions in the separator comprise means for controlling the relative proportions of the air flow passing through the separating zone and bypassing the separating zone.

Preferably the means for controlling the relative proportions of the air flow comprise a cylindrical housing accomodated in the separator and coaxial therewith, the housing being connected to an outlet of the separator for the flow of air, the housing being provided with at least one opening of adjustable size in its side wall, a tube extending downwardly from the housing for providing communication between the interior of the housing and the discharge zone, the lower end of the tube being vertically adjustable in position. Preferably the cyclone separator is provided with a discharge pipe for outlet of the separated fibrous material from the discharge zone, the discharge pipe being provided with valve means for controlling outlet of the fibrous material through the pipe.

The invention is further described below by way of example with reference to the accompanying drawing which diagrammatically illustrates an apparatus embodying the invention.

Referring to the drawing, air is propelled through a conduit system 3, 4 by means of a blower 2. At the exhaust side of the blower there is superatmospheric pressure in the portion 3 of the conduit system, and at the inlet side of the blower there is a subatmospheric pressure. At the exhaust side of the blower there is provided supply means 1 for supplying fibres to the conduit system. The supply means may be a refining machine and/or a disintegrating machine connected to the conduit system. The supply means feeds the conduit system with fibres and is driven by an electric motor, not shown. A tank S is connected to the conduit system by means of a tube 6. In the tube 6 there is provided a damper 7 for controlling the flow of air through the tube 6. The tank is provided with an exhaust pipe 9, the free end of which carries a bag filter 10.The contents of the tank, i.e. fibres collected therein can be discharged by opening a shutter 11 at the bottom of the tank.

In the conduit system between the tank S and a cyclone separator 12 there is provided a damper 20 for choking air flow through the conduit system so that an atmospheric or subatmospheric pressure results in the portion 4 of the conduit and in the separator 12.

The portion 4 of the conduit system leading from the damper 20 is connected to the cyclone separator 12. In the upper, central part of the cyclone separator 12 there is provided a cyclinder 13. This has, at an upper portion thereof, one or more openings 15, which can be closed partly or even completely by means of shutters. The upper end of the cylinder 13 is connected to the portion 4 of the conduit system leading to the blower 2. The bottom of the cylinder has an opening in which a tube 14 is provided displaceable upwards and downwards. At the lowest portion of the cyclone separator there is provided a tube 16 displaceable upwards and downwards, the purpose of the tube 16 being discharge of fibres from the conduit system 3, 4. The tube 16 has a somewhat smaller diameter at its upper end than at its lower end in order to prevent the fibres from adhering to each other or to the tube so that the tube is obstructed or plugged. In the side surface of the cyclone there is provided a window 17 covered by a transparent plastic material.

At this window there is provided a photocell device 18 connected to a relay for regulating the power supply to the (not shown) electric motor driving the supply means 1. In the portion 4 of the conduit system there is provided a damper 8 for choking the conduit so that the flow rate of air through the conduit system 3, 4 is regulated. It is also possible to obtain this regulating effect by controlling the speed of the motor driving the blower 2.

In the tube 16 there is provided a shutter 19, which can be opened or closed according to signals from the machine receiving the fibres.

The blower 2 propels a flow of air through the conduit system 3, 4. The supply means 1 produces fibrous material which is fed to the conduit system. At the exhaust side of the blower there is a superatmospheric pressure in the conduit. The superatmospheric pressure is eliminated mainly by letting air flow through the pipe 6 into the tank 5. Accompanying the air into the tank is a certain percentage of fibres of short length and low density. The main part of the fibrous material is, however, carried by the air flowing to the portion 4 of the conduit system and to the cyclone 12. The air and certain of those fibres flowing into the tank 5 are permitted to flow through the pipe 9 into the bag filter 10, from where the air escapes whilst the fibres are collected therein.However, most of the fibrous material carried by the air into the tank 5 through the pipe 6 falls down at the bottom of the tank 5 from where it can be discharged when desired by opening the shutter 11. If the damper 7 in the pipe 6 is completely open and the damper 20 partially closed the portion 4 of the conduit is relieved of pressure so that even a subatmospheric pressure can be obtained therein.

When air and fibres are flowing into the cyclone separator they are separated in two steps. The first step comprises letting some of the air and a minor percentage of the fibres flow into the.cylinder 13 through the openings 15. The remaining air and the main part of the fibres are rotating in the cyclone in a descending whirl-like motion.

The second step of separation comprises letting this air and a certain percentage of the fibres present in the lower portion of the separator flow into the tube 14 whilst the main part of the fibrous material falls down into the tube 16. In the separator there is an atmospheric or somewhat lower pressure.

These pressure conditions result in the fibres falling very gently and slowly into the tube 16 without being becoming packed, which is a prerequisite of good discharge conditions. The tube 16 flares downwardly in order to enhance the discharge and to avoid builing up of plugs of fibrous material when the shutter 19 is closed. Fibres are discharged from the conduit system via the tube 16 and are fed to the fibre-consuming machine in which the fibres are further processed. When this machine is operating the shutter 19 is open and when this machine is shut down the shutter is closed under influence of impulses from the machine.

If facilities for discharging fibres from the cyclone separators under far more accurate and controllable conditions are desired the shutter 19 is dispensed with and the telescopic tube 16 is connected to a dispensing apparatus, for example according to the British Patent application 6287/77 (Serial No. 1549563).

What is happening in the lower part of the cyclone separator between the lower end of the tube 14 and the upper end of the tube 16 is of great importance for a good function of the apparatus. It is essential that the air in this area has a proper flow rate. This is achieved by means of the openings 15, which are provided with shutters for adjusting the effective cross sectional area of the openings. If the flow rate is too high too much fibrous material is carried out through the telescope tube 14. If the flow rate is too low piling up of fibres can occur in this lower part of the cyclone which results in too much fibrous material being collected at the upper end of the tube 16 particularly when the shutter 19 has been closed for a while.

Furthermore, it is important that the distance between the upper end of the tube 16 and the lower end of the tube 14 has the correct value. This distance is selected in such a way that with the shutter 19 closed the tube 16 is filled with fibres to a level a few centimetres below the upper end thereof. Further fibres are carried away by the flow of air up through the tube 14.

Thus within the separator 12 there are established a separating zone around and under the lower end of the tube 14 and a discharge zone adjacent and within the upper end of the tube 16. Part of the flow of air passes through the separating zone at a low speed and at least part of the fibrous material separates from the flow of air in the separating zone and falls into the discharge zone without experiencing agglomeration.

In the discharge zone, the air is static and the separated fibrous material thus does not experience agglomeration.

In the lower part of the cyclone separator there is provided the window 17. Close to the window 17 the photocell device 18 is provided. The photocell device can be a transmitter of light and a receiver as well and can have adjustable sensitivity. The light emitted from the photocell device is directed through the transparent plastics window. The photocell device is connected to a relay, which regulates the power supply to the motor driving the supply means 1.

When the shutter 19 is closed no discharge of fibres from the system occurs. The concentration of fibres in the fibre-air mixture whirling at the window 17 starts to increase and so does the amount of reflected light therefrom, the electric motor driving the supply means 1 accordingly being shut down by the photocell device. The fibrous material present in the apparatus at this moment is then recirculated through the conduit system. When the shutter 19 is then opened fibres are discharged from the system through the tube 16 causing the percentage of fibres in the air at the window 17 to start the decrease. This causes the electric motor to be again started by the photocell device 18 and, whilst the shutter 19 remains open, the photocell device controls the speed of the electric motor to maintain the concentration of fibres in the air at the window 17 substantially constant.

The supply means 1 feeds the conduit system not only with fibres but also with air.

Furthermore, the conduit system is supplied with some air at the portion 4 thereof on the inlet side of the blower where a subatmospheric pressure is present because of the fact that air is drawn through slits and such joints as are impossible to completely seal in practice. The air admitted into the conduit system in these ways is exhausted therefrom through the filter 10.

More than one cyclone separator can be connected to the conduit system either in series or in parallel.

WHAT WE CLAIM IS: 1. A method of transporting fibrous material, comprising: providing a flow of air passing along a conduit and introducing the fibrous material into the conduit so that it is carried along the conduit by the flow of air, the flow of air passing from the conduit into a separator; maintaining the air pressure in the separator substantially equal to the air pressure exterior to the separator and controlling the air flow. conditions in the separator to establish within the separator a first or separating zone through which at least part of the flow of air passes and a second or discharge zone in which the air is substantially static, at least part of the fibrous material separating from the flow of air in the separating zone and falling into the discharge zone without experiencing agglomeration; when the discharge zone is open to the exterior of the separator, the fibrous material being discharged from the separator without experiencing agglomeration, by being allowed to fall from the discharge zone to the exterior of the separator; and maintaining the concentration of fibrous material in the flow of air at a predetermined point substantially constant.

2. A method according to claim 1, wherein the concentration of the fibrous material in the flow of air in the first or separating zone of the separator is measured and the rate of introduction of the fibrous material into the conduit is controlled in dependence on the measured concentration so as to maintain the concentration of fibrous material ir; the flow of air substantially constant.

3. A method according to claim 1 or 2, wherein air is allowed to escape from the conduit at a point upstream of the separator.

4. A method according to any preceding claim, wherein the flow of air from the separator and containing any unseparated fibrous material is recycled back to the conduit.

5. A method according to any preceding claim, substantially as described herein with reference to the accompanying drawing.

6. Apparatus for carrying out a method according to claim 1, comprising: a conduit; a fan or blower arranged for providing a flow of air along the conduit; means for introducing fibrous material into the conduit in order for the fibrous material to be carried along the conduit by the flow of air; a separator to which the conduit leads; means for maintaining the air pressure in the separator substantially equal to the pressure exterior to the separator and means for controlling air flow conditions in the separator to establish within the separator a first of separating zone through which at least part of the flow of air passes and a second or discharge zone in which the air is substantially static the fibrous material being able to fall from the separating zone into the discharge zone; means for allowing separated fibrous material to fall from the discharge zone to the exterior of the separator; and means for measuring the concentration of fibrous material in the flow of air of a predetermined point and controlling the rate of introduction of fibrous material into the flow of air to maintain the concentration of fibrous material in the flow of air at the predetermined point substantially constant.

7. Apparatus according to claim 6, wherein the separator is a cyclone separator and the means for controlling air flow conditions in the separator comprise means for controlling the relative proportions of the air flow passing through the separating zone and bypassing the separating zone.

8. Apparatus according to claim 7, wherein the means for controlling the relative proportions of the air flow comprise a cylindrical housing accommodated in the separator and coaxial therewith, the housing being connected to an outlet of the separator for the flow of air, the housing being provided with at least one opening of adjustable size in its side wall, a tube extending downwardly from the housing and providing communication between the interior of the housing and the discharge zone, the lower end of the tube being vertically adjustable in position.

9. Apparatus according to claim 8,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. light therefrom, the electric motor driving the supply means 1 accordingly being shut down by the photocell device. The fibrous material present in the apparatus at this moment is then recirculated through the conduit system. When the shutter 19 is then opened fibres are discharged from the system through the tube 16 causing the percentage of fibres in the air at the window 17 to start the decrease. This causes the electric motor to be again started by the photocell device 18 and, whilst the shutter 19 remains open, the photocell device controls the speed of the electric motor to maintain the concentration of fibres in the air at the window 17 substantially constant. The supply means 1 feeds the conduit system not only with fibres but also with air. Furthermore, the conduit system is supplied with some air at the portion 4 thereof on the inlet side of the blower where a subatmospheric pressure is present because of the fact that air is drawn through slits and such joints as are impossible to completely seal in practice. The air admitted into the conduit system in these ways is exhausted therefrom through the filter 10. More than one cyclone separator can be connected to the conduit system either in series or in parallel. WHAT WE CLAIM IS:

1. A method of transporting fibrous material, comprising: providing a flow of air passing along a conduit and introducing the fibrous material into the conduit so that it is carried along the conduit by the flow of air, the flow of air passing from the conduit into a separator; maintaining the air pressure in the separator substantially equal to the air pressure exterior to the separator and controlling the air flow. conditions in the separator to establish within the separator a first or separating zone through which at least part of the flow of air passes and a second or discharge zone in which the air is substantially static, at least part of the fibrous material separating from the flow of air in the separating zone and falling into the discharge zone without experiencing agglomeration; when the discharge zone is open to the exterior of the separator, the fibrous material being discharged from the separator without experiencing agglomeration, by being allowed to fall from the discharge zone to the exterior of the separator; and maintaining the concentration of fibrous material in the flow of air at a predetermined point substantially constant.

9. Apparatus according to claim 8,

wherein the cyclone separator is provided with a discharge pipe for outlet of the separated fibrous material from the discharge zone, the discharge pipe being provided with valve means for controlling outlet of the fibrous material through the pipe.

10. Apparatus according to claim 9, wherein the upper end of the discharge tube is vertically adjustable in position.

11. Apparatus according to any of claims 8 to 10, wherein the means for measuring the concentration of fibrous material in the flow of air comprises a photocell provided at a window in a wall of the separator and adjacent the lower end of the discharge tube.

12. Apparatus according to any of claims 6 to 8, wherein the means for maintaining the air pressure in the separator substantially equal to the pressure exterior to the separator comprises a first valve in the conduit (hereinafter referred to as the "first-mentioned conduit") upstream of the separator and downstream of the fan and a second valve in a branch conduit leading from the first conduit.

13. Apparatus according to claim 12, wherein the second valve communicates with the atmosphere through a filter for filtering fibrous material from air which has passed from the first-mentioned conduit through the second valve.

14. Apparatus according to claim 13, wherein a container is connected to the second valve for holding fibrous material carried in air which has passed from the first-mentioned conduit through the second valve.

15. Apparatus according to claim 6, substantially as described herein with reference to and as illustrated in the accompanying drawing.