AU1987199A - A dosing device and a method for dosed feeding of grained, pelletized or granulated mass material out from a container - Google Patents

Description

WO99/29166 1 PCT/NO98/00371 A dosing device and a method for dosed feeding of grained, pelletized or granulated mass material out trom a counL±aiier. The invention relates to a dosing device for feeding out doses of grained, pelletized or granulated material from a container, particularly for feeding out pelletized fish fod 5 der from a silo. Grained, pelletized or granulated material, in the following called pellets, is often stored in a silo, from where feed out occurs close to the bottom, while filing of new material is effected from the top of the silo. An advantage with this 10 is that the oldest material substantially is located lower most in the silo and becomes fed out first. The arrangement also makes it possible to utilize the gravity in an advanta geous way in order to achieve controlled feed out of pellets by means of a dosing device. 15 A simple known dosing device comprises a flap or a hatch capable of opening and closing an outlet aperture lowermost in the silo. When the hatch is opened, pellets flow out from the silo, down into a vessel or down onto a conveyer belt be low the silo. When the desired amount of pellets has been 20 drawn off, the hatch closes the outlet aperture. The amount can often be determined with sufficient accuracy by control ling the opening time of the hatch by means of a timing de- WO99/29166 2 PCTIN0O98/00371 vice. Better accuracy can be achieved by means of a control ler receiving signals from a weight or volumetric measuring accessory, the signal value being compared to a predetermined value. 5 In some cases, a silo may be placed straight above the place where the dosed material is used. Examples of this technique are silos associated with simple mixing plants and silo shaped automatic fodder containers somewhat spaced above the water surface in fish vessels or fish "merds". 10 Very often, the dosed material is to be used at a place spaced from the silo, and the dosing device is then combined with a conveyor, e.g. a conveying belt such as previously mentioned. A much used dosing device comprises a conveying screw within 15 a channel, where the outlet aperture of the silo opens straight into the channel, without any intermediate flap or hatch. When the conveying screw is not rotating, it effi ciently prevent material from flowing out from the silo. A rotary sluice is another dosing device very much used, 20 comprising a shovel bringing pellets from the outlet aperture of the silo to a pipe where flowing air or liquid conveys dosed material further on. Conveyor screws and rotary sluices are simple and robust. Additionally, they can easily be adapted to give volumetric 25 measure of dosed amount by counting revolutions. Moreover, the rotational speed of the conveyor screw and of the shovel may easily be changed in order to achieve desired volume rate.

WO99/29166 3 PCT/NO98/00371 In order to enable to empty a pellet silo completely, it is usual that the lowermost portion of the silo is shaped as a funnel. Anyone versed in the art is aware of that pellet bridges may 5 form if the funnel angle is too large. A pellet bridge re sults in that only pellets beneath the bridge reach the out let aperture of the silo. A small funnel angle results in that the funnel becomes relatively high and in that the fun nel volume is small. 10 Also, it is known to be advantageous to couple the outlet ap erture of the silo to an expansion chamber having a larger lateral measure than the outlet aperture of the silo, so that the pellet mass is allowed to expand after having passed through the outlet aperture. Thus, a much used silo type 15 opens out within a ball-shaped chamber having a substantially larger diameter than the outlet aperture of the silo. The diameter of the expansion chamber is also significantly larger than the diameter of a conveyor screw extending through the expansion chamber. By using a rotary sluice, the 20 pellet material is allowed to expand in the shovel. Pellet bridges occur even with a small funnel angle and ex pansion chamber. It is, thus, usual to provide the expansion chamber, the sluice housing or the silo wall with an inspec tion hatch where it is possible to reach a pellet bridge with 25 a tool to loosen up the bridge. A silo for pellets becomes relatively tall. First, as men tioned, it is necessary with a tall funnel and, secondly, it is an advantage to have an expansion chamber in connection with a dosing device below the outlet aperture, and these 30 measures contribute to increase the silo height. Tall silos are, generally, a disadvantage, and a resultant point of gravity at a high level is particularly a disadvantage on board floating installations.

WO 99/29166 4 PCT/N098/00371 Silos are often placed such that it is difficult to reach the area below the silo in order to maintain the dosing device or to loosen up a pellet bridge through an inspection hatch. Technical installations beneath or immediately adjacent a 5 silo also makes it difficult to pass a conveyor screw or con veying belt for pellets out from the silo. Another case is that there might be a need for a plurality of outlets from one silo. It is known to have several hatches or flaps side by side and, correspondingly, several conveyor 10 belts in order to convey pellets to a plurality of places of use. Also, solutions comprising two silos having a common ex pansion chamber are known. Several outlets become often both space-demanding and impractical. The object of the invention is to provide a method in dosing 15 and a dosing device where said disadvantages have been avoided. The object is achieved through features as defined in the following specification and claims. According to the invention, pellets are sucked out from the 20 silo by means of a flow of air within a pipe connected to the suction side of one or another low-pressure source, and where the free end of the pipe is passed into the silo and into the pellet mass. The pipe may be assigned a sluice device, a cy clone or another apparatus adapted to receive pellets accom 25 panying the air flow. Negative pressure within the pipe draw air from the area above the pellet mass, through the pellet mass and into the pipe at the open, lower end thereof. Pel lets close to the end of the pipe, are entrained into the pipe and further upwardly within the pipe by means of the 30 flow of air.

WO99/29166 5 PCT/NO98/00371 A controlled valve can open and close at least one gate in the pipe wall. When the gate is closed, air flows into the pipe at the free end thereof, such as mentioned. When the valve is open, air flows into the pipe through the gate. Pel 5 lets within the pipe, downstream of the gate, is conveyed further by means of air entering into the pipe through the gate. Supply of new pellets at the open end of the pipe stops, be cause the air speed there is too small to entrain pellets 10 when the gate is open. Thus, pellets may be dosed into the pipe through changing the valve between closed and open posi tion. The invention can be embodied in several ways. It should be made provisions preventing pellets from accompanying air 15 flowing through the valve, so that pellets do not enter the pipe or clogs the valve. This may be achieved in a simple manner by shielding the valve, e.g. with a net having so small meshes that pellets can not pass. Further, it may be advantageous to dispose a movable arm ad 20 jacent the open end of the pipe. The movements of the arm loosens up a possible local pellet bridge preventing flow of pellets therethrough. In the following, an exemplary embodiment of the invention is discloses; reference is made to the attached drawings, 25 wherein: Figure 1 shows diagrammatically in side elevational view a silo having a dosing device; Figure 2 shows the dosing device, on a larger scale, in sec tion in side view, the dosing device occupying an operative 30 condition; WO99/29166 6 PCT/NO98/00371 Figure 3 shows the dosing device, on a larger scale, in sec tion in side view, the dosing device occupying an inoperative condition. In figure 1, reference numeral 1 defines a dosing device 5 placed within a silo 2 containing pellets 3. By means of a conveying hose 4, the dosing device 1 is cou pled to the suction side of a fan 5, possibly a compressor, an ejector or another apparatus suitable to create a negative pressure within the conveying hose 4. 10 Further, the dosing device 1 is connected to a pressure air source 6 by means of a pressure air pipeline 7 through a con trolled valve 8. A controller 9 is connected to the con trolled valve 8 and adapted to give it signals to open or to close. 15 The dosing device 1 which in figure 2 is shown in operative, vertical position of use, comprises a central pipe 10 coupled to the conveying hose 4 and constitutes an extension thereof. In the wall of the pipe 10 is formed some holes 11, admitting flows of air into the pipe 10. An axially displaceable sleeve 20 12 surrounding the pipe 10, is provided with holes 13 posi tioned in a similar pattern as the holes 11 in the pipe 10, so that the holes 13 in the sleeve 12 can be brought to over lap the holes 11 in the pipe 10 by displacing the sleeve 12 along the pipe 10. 25 When the sleeve 12 occupies a first operative end position, such as shown in figure 2, the holes 13 do not overlap the holes 11. Then, negative pressure within the hose 4 and pipe 10, results in that air and pellets flow into the pipe 10 at the open end thereof.

WO99/29166 7 PCT/NO98/00371 When the sleeve 12 occupies another, inoperative end posi tion, such as shown in figure 3, the holes 13 overlap the holes 11. Then, negative pressure within the hose 4 and pipe 10 results in that air flowing into the pipe through the 5 holes 13,11. Air flowing into the pipe 10 at the open end thereof, attains then a too small speed in order to draw pel lets 3 into the pipe 10. A perforated screen 14 surrounds a substantial portion of the pipe 10 and prevents that surrounding pellets 3 come into 10 contact with the sleeve 12, the screen 14 extending between a first flange 15 and a second flange 16 attached to the pipe 10. The distance between the flanges 15, 16 is such that the flanges 15, 16 may serve as end stops for the sleeve 12. The screen 14 is made of net or perforated material having so 15 small openings that pellets 3 cannot pass therethrough. At its outer periphery, an annular diaphragm 17 is pressure sealingly attached to the first flange 15, at that side fac ing the second flange 16, by means of a ring 18 and screws, not shown. Further, the diaphragm 17 is pressure-sealingly 20 attached to the sleeve 12 between a first disc 19 and a sec ond disc 20 by means of screws, not shown, the second disc 20 being pressure-sealingly attached to the sleeve 12. By means of a nipple 21, the pressurized air pipeline 7 is connected to a gate 22 in first flange 15, so that pressur 25 ized air can be supplied between first flange 15 and the dia phragm 17. A pretensioned spring 23 acting between second flange 16 and second disc 20, keeps the sleeve 12 in first end position, see figure 2. The sleeve 12 can be displaced against the 30 force from the spring 23 to second end position, figure 3, through the supply of pressurized air between first flange 15 and the diaphragm 17.

WO99/29166 8 PCT/NO98/00371 Upon periodically supply of pressurized air, the sleeve 12 can be brought to alternate between first and second end po sition. A strut 24 extending parallell to the pipe 10 is, at one end 5 thereof, attached to second disc 20 and penetrates second flange 16. Thus, the strut 24 follows the movements of the sleeve 12. Onto the free end of the strut 24 is fastened an arm 25 sub stantially extending laterally of the pipe 10 at a distance 10 from the free end of the pipe 10. The movements of the arm 25 loosen up a possible pellet bridge which may prevent supply of pellets at the free end of the pipe 10. Also, the sleeve 12 could of course have been adapted such that it turns between two end positions, the sleeve 12 in one 15 end position closing the holes 11 in the pipe 10 and opening the holes 11 in the pipe 10 in the other end position. Upon a need for several outlets from a silo 2, a plurality of dosing devices 1 are installed within the silo 2.

Claims (7)

1. A method for dosed feeding of grained, pelletized or granulated mass material (3) out from a container (2), particularly for dosing pelletized fish fodder from a 5 silo, wherein the feed out operation is based on suction effect and the use of a conveying pipeline/hose (4) hav ing a preferably tubular suction mouthpiece (10) exhibit ing at least one suction opening for mass material and a number of air suction openings (11), 10 c h a r a c t e r i z ed in that the perforated area of the suction mouthpiece (10) is surrounded by a radi ally outermost, correspondingly perforated sleeve (12) which is transferred between two end positions, wherein the holes (11, 13) in the suction mouthpiece (10) and in 15 the sleeve (12) are brought to substantially overlap each other paired in a first end position and brought to sub stantially not overlap each other in a second end posi tion, and that, in the first end position, such a consid erable air flow is established in through the air suction 20 openings (11,13) that the air flow through the pellet suction opening is reduced and weakened in respect of flow speed to such an extent that pellets can not be drawn into the suction mouthpiece (10) and up through the conveying pipeline/hose (4), while, in the second po 25 sition of the perforated sleeve (12) upon the blockage of the air suction openings (11,13), a sufficient admission velocity is established at said pellet suction opening to cause efficient feed out of pellets from the silo (2), the perforated sleeve (12) being rapidly transferred be 30 tween the two end positions thereof, such as pellet feed out being started and stopped immediately.

2. A dosing device (1) for dosed feeding of a grained, pel letized or granulated mass material (3) out from a con tainer (2), especially for dosing pelletized fish fodder 35 from a silo, and based on suction effect through a con- WO99/29166 10 PCT/N0O98/00371 veying pipeline/hose (4) having a preferably tubular suc tion mouthpiece (10) at the free end thereof, said suc tion mouthpiece (10) having at least one, relatively large suction opening for the passage of pellets, grains 5 or granules into the conveying pipeline (4) and a number of laterally directed air suction holes (11), c h a r a c t e r i z e d i n that an outermost, transferable sleeve (12) surrounds the suction mouthpiece (10) and is correspondingly perforated, the holes (13) of 10 the sleeve (12) upon the transfer thereof between two end positions, in one end position being brought to overlap the suction mouthpiece's (10) corresponding holes (11) to a sufficient degree to weaken the suction capacity of the suction mouthpiece (10) at the suction opening(s) for 15 mass material to such an extent that the air flow there acquires a too small speed to draw with it pellets, etc., the holes (13) of the sleeve (12) in the other end posi tion not at all or to a neglectable degree overlap the holes (11) of the suction mouthpiece (10) so that the 20 latter is completely or substantially tight, except from the pellet suction opening(s).

3. A dosing device as set forth in claim 2, c h a r a c t e r i z ed in that the perforated, transferable sleeve (12) is displaceable in the axial di 25 rection of the suction mouthpiece (10).

4. A dosing device as set forth in claim 2, c h a r a c t e r i z e d i n that the sleeve (12) is assigned an actuator.

5. A dosing device as set forth in claim 3 and 4, 30 c h a r a c t e r i z e d i n that the sleeve (12) is surrounded by a screen (14) of net, netting or other per forated plate material and which lowermost is terminated at a distance from the suction mouthpiece's (10) lower, free, open end which constitutes the suction opening for WO99/29166 11 PCT/NO98/00371 mass material, and wherein the net's openings are smaller than the particle size of grain, granules, pellets, etc. constituting the mass material.

6. A dosing device as set forth in claims 3-5, 5c h a r a c t e r i z e d i n that a strut (24) ex tending substantially axially parallel to the tubular suction mouthpiece (10), at the free end being the lower most in the position of use, carries a lateral arm (25) spaced below the lower, free end of the suction mouth 10 piece (10).

7. A dosing device as set forth in the preceding claims, c h a r a c t e r i z e d i n that the perforated sleeve (12), at the upper end thereof, is suspended from an an nular, deformable diaphragm (17) which, at least at its 15 outer circumferential portion, is attached indisplaceably to the tubular suction mouthpiece (10) and, at its inner circumferential portion is attached, in a similar way to the perforated sleeve (12), said diaphragm (17) being ex pandable/collapsible to such an extent in the longitudi 20 nal axial direction of the tubular suction mouthpiece (10) that corresponds to the necessary displacement dis tance of the sleeve (12) between its two end positions.