APPARATUS FOR FEEDING POWDERY MATERIAL

Abstract: The invention relates to an apparatus for feeding powdery material from a heap of material into a conveyor, comprising a pressure feeder (1) connected to a source of pressure and provided with an inlet (5) for the powdery material and an outlet leading into the conveyor (4); and means (2) for transferring the powdery material from below the apparatus into the inlet (5). To make the operation of the apparatus more efficient, said means (2) comprise a sequence of scoops arranged to move endlessly around the apparatus, and a protective casing (10) positioned on one side of the apparatus for receiving the scoops (9) when they move away from the inlet (5), so that the apparatus is able to dig itself evenly into the heap of material while the scoops (9) transfer material into the inlet (5).

Description: Apparatus for feeding powdery material This invention relates to an apparatus for feeding powdery material from a heap of material into a conveyor, comprising a pressure feeding means connected to a source of pressure and provided with an inlet for the powdery material and an outlet leading to the conveyor; and means for transferring the powdery material from below the apparatus into the inlet of the pressure feeding means so that the apparatus is able to dig itself into the heap of material. EP Patent Application 0 142 031 discloses an apparatus for feeding powdery material. The tubular body of the apparatus is connected at its lower end to a pneumatic conveyor and at its upper end to transverse stubs to which powdery material is fed by screw conveyors extending up to the lower end of the body. The screw conveyors transport material from below the body to its upper end, from where the material passes to the lower end of the body and further into the conveyor. This known apparatus has a relatively low capacity and its operation requires continuous feeding of material by the screw conveyors from below the body into its interior, end so the power demand of the apparatus is relatively lic . Fo- the same reason, the apparatus may dig itself to deep into the heap. DE Offenlegungsschrift 2 051 539 another apparatus for feeding powdery material into a conveyor. The apparatus comprises two endless sequences of scoops arranged symmetrically beside a suction pipe and moving around rolls. The purpose of the lines of scoops is to gather material at the nozzle opening of the suction pipe and to break up lumps of material so that the powdery material can be sucked into the suction pipe without the nozzle open¬ ing being clogged. The drawbacks of this apparatus include a relatively low capacity, a great power demand caused by the suction operation and the un¬ reliability of the proper operation of the sequence of scoops. Also, a feeding apparatus for powdery material is previously known in which there is provided a pressure feeder comprising two cup-like portions hinged together. When open, the pressure feeder scoops material out of the surface of the heap, whereafter it is closed and compressed air is introduced into it so as to feed the material into a conveying tube. A problem with this apparatus is the difficulty in sealing the feeder when it is closed, in addition to which the feeding operation of the apparatus is slow. The object of the present invention is to provide an apparatus for feeding powdery material with a considerably lower power demand and a higher capacity than the above-mentioned apparatuses known from the prior art. This is achieved by means of an apparatus according to the invention, which is characterized in that the means for transferring the powdery material from below the apparatus into the inlet of the pressure feeding means comprise a sequence of scoops arranged to move endlessly around the apparatus, and a protective casing positioned on one side of the apparatus for receiving the scoops when they move away from said inlet. The basic idea of the invention is that after the apparatus has been placed on a heap formed by a powdery material, it is able to dig itself into the heap by the action of the sequence of scoops moving around the apparatus while the scoops transfer material into the inlet of the pressure feeding means, from where the material is further fed into the conveyor. To ensure that the apparatus sinks evenly and substantially vertically into the heap of material, the material is dug and lifted by means of scoops rising from one side of the apparatus. After the scoops have delivered the material into the inlet, and move away from it, they enter the protective casing, within which they are able to move downwards without making contact with the powdery material. In this way, the scoops do not push the material deeper into the heap when moving downwards, which would cause extra strains and an increase in the power consumption and tend to brake and incline the apparatus. When the apparatus is positioned within the heap, the digging, however, can be interrupted as the construction of the apparatus enables it to receive powdery material flowing into the pressure feeder from above the apparatus under the influence of the force of gravity. This is possible as the inlet opens into the surroundings substantially upwards. It is clear that an apparatus in which active transfer of material into the pressure feeder is required only intermittently has a lower power demand than apparatuses where the transfer means operate continuously. Dust formation is also avoided. In the following, an exemplifying embodiment of the apparatus according to the invention will be described in greater detail with reference to the attached drawings, in which Figure 1 shows an apparatus according to the invention in a vertical section along the line I...I of Figure 2; Figure 2 is a side view of the apparatus; and Figure 3 is a top view of the apparatus. The apparatus shown in the drawings mainly comprises a pressure feeder 1 and means 2 for transferring powdery material from below the apparatus into the pressure feeder 1. The pressure feeder is connected to a source of pressure not shown by means of a tube 3 and to a conveying tube 4 which transfers the powdery material into a storeroom or the like. The apparatus according to the invention is positioned in a heap of powdery material, e.g. in the hold of a vessel. The pressure feeder 1 also com¬ prises an inlet 5 for the powdery material. The pressure feeder is surrounded by a metal housing 6, on the outside of which, preferably at its top and bottom corners, there are provided three pairs of pulleys 7, through which two parallel chains 8 pass. Successive scoops 9 preferably formed by elongated, substantially trough-like plates are attached to the chains so as to form a sequence of scoops, which moves within a protective casing 10 on one side of the metal housing. The protective casing is attached to the metal housing 6 surrounding the apparatus and it is arranged to extend substantially from the central line of the inlet 5 of the pressure feeder 1 close to. the lower end of the apparatus. The protective casing thus prevents the scoops 9 from sticking in the powdery material when they move down¬ wards with respect to the operating position of the apparatus. The length of the scoops 9 is substantial¬ ly equal to the width of a filling hopper 11 provided at the inlet 5. No protective casing is provided at the lower end of the apparatus and on the opposite side of the housing. The movement of the scoops attached to the chains around the apparatus is effected by means of two synchronized drive motors 17. The tightness of the chains 8 can preferably be adjusted by making one pair of pulleys 7, e.g. the pair at the bottom of the apparatus, displaceable. It is thereby possible to provide a guide plate 19 dis¬ placeable along the lower wall of the metal housing 6 in connection with said displaceable pair of pulleys 7 on the opposite side of the apparatus with respect to the protective casing 10. The guide plate can be displaced in accordance with the position of the dis¬ placeable pair of pulleys in such a way that the scoops are continuously supported on the side of the apparatus when they move upwards. As a consequence, after the scoops 9 emerge from the protective casing 10 and turn at said pair of pulleys 7, they come into contact -with the powdery material and transfer it into the inlet 5 of the pressure feeder. After having delivered the powdery material, the scoops 9, which are now substantially empty, enter the protective casing 10 to start another round. The apparatus sinks evenly into the heap of material while the powdery material is transferred into the inlet of the pressure feeder. The movement of the scoops can be interrupted for reasons to be discussed below. The pressure feeder is a substantially cylindrical container. The tube 3 for compressed air is connected to the side of the container, the conveying tube 4 is connected to one end of the container, and the inlet 5 for powdery material is positioned at the opposite end of the container, which in the normal operating position of the apparatus is the upper end of the pressure feeder. The inlet 5 thus opens upwards and it comprises a filling hopper 11 similarly opening upwards, above which the scoops 9 move in the horizontal direction. The inlet 5 comprises a valve 12 which is a disc valve in the embodiment shown. In the embodiment shown in the drawings, the pressure feeder 1 comprises two chambers 13 and 14 positioned on top of each other and communicating with each other through an opening 15 in which a valve 16, such as a disc valve, is provided. The pressure tube 3 is connected to the upper portion of the chamber 13, and the conveying tube 4 is connected to its lower end. The inlet 5 for powdery material and the filling hopper 11 are positioned at the free end of the chamber 14, that is, at its pper end, and so the powdery material can freely enter the filling hopper. The openings 5 and 15 have a common central line which is substantially vertical in the operating position of the apparatus when the inlet 5 is posi¬ tioned above the opening 15 between the chambers 13 and 14. A lifting lug at the upper end of the apparatus is indicated with the reference numeral 18. The feeding apparatus according to the invention operates in the following way. When empty¬ ing the hold of a ship, the apparatus, suspended from the lifting lug 18, is lowered down into the hold on the powdery material. When the transfer means 2 for the powdery material, that is, the sequence of scoops, are started, the apparatus begins to dig it¬ self into the heap of powdery material while the scoops 9 transport material from below the apparatus to its upper end, from where the material flows into the filling hopper 11 as a result of the position of the scoops. When the valve 12 of the inlet 5 is open, the material flows further into the chamber 14. When the valve 12 is closed, the valve 16 opens, so that the material flows further into the chamber 13. When the valve 16 is closed, the material contained in the chamber 13 is transferred under the influence of compressed air applied from the tube 3 into the conveying tube 4, during which time the chamber 14 is refilled. When the valve 12 is closed, the material gathers in the filling hopper 11. As the transfer means 2 operate, the apparatus sinks deeper and deeper in the heap of material. After the apparatus has fully sunk in the powdery material, the transfer means are stopped, so that material flows under the influence of the force of gravity from between the scoops 9 into the filling hopper 11 and further into the pressure feeder 1 as described above. Accordingly, only the source of pressure and the valves of the pressure feeder are in operation at this stage. After the surface of the heap of material has sunk in level with the filling hopper, no material flows into the hopper under the influence of the force of gravity, and the apparatus is displaced downwardly or sidewardly to another position. The bottom layer of the material has to be fed into the pressure feeder by means of the scoops. As distinct from the above-described embodi¬ ment, the pressure feeder 1 may comprise a sir-gle chamber, and so the valve 16 can be omitted. Tht pressure feeder may also be of different shape th.- that described above, e.g. cubic. Essential is t? the inlet of the pressure feeder is such that it able to receive powdery material both from -i.-^. transfer means 2 and as a result of the free flow of material. Therefore it is required from the inlet that it communicates directly with both the transfer means and the surroundings. On the basis of the above, it is obvious that the plane of the inlet need not be accurately horizontal in the operating position of the apparatus, but it may be inclined. It is also to be noted that the valve 12 may be posi¬ tioned even in the vertical plane, if the filling hopper leading into it opens upwards, that is, the plane defined by the edge of the hopper is substantially horizontal. The chambers 13, 14 of the pressure feeder 1 need not be positioned on top of each other as shown in the drawings, but they may as well be positioned side by side, for instance. Furthermore, the structural details of the scoop displacing mechanism may be modified within the scope of the attached claims.

Claims: Claims : 1. Apparatus for feeding powdery material from a heap of material into a conveyor, comprising a pressure feeding means (1) connected to a source of pressure and provided with an inlet (5) for the powdery material and an outlet leading to the conveyor (4); and means (2) for transferring the powdery material from below the apparatus into the inlet (5) of the pressure feeding means (1) so that the apparatus is able to dig itself into the heap of material, c h a r a c t e r i z e d in that the means (2) for transferring the powdery material from below the apparatus into the inlet (5) of the pressure feeding means (1) comprise a sequence of scoops arranged to move endlessly around the apparatus, and a protective casing (10) positioned on one side of the apparatus for receiving the scoops (9) when they move away from said inlet (5). 2. Apparatus according to claim 1, c h a r a c¬ t e r i z e d in that the sequence of scoops is formed by successive elongated, substantially trough¬ like* plates (9) interconnected at respective ends by means of two chains (8), the chains with the scoops attached to them being arranged to move around via pairs of pulleys (7) provided in connection with the end corners of the apparatus. 3. Apparatus according to claim 1 or 2, c h a r a c t e r i z e d in that the length of the scoops (9) formed by substantially trough-like plates is equal to the width of a filling hopper provided at the inlet (5) of the pressure feeding means (1). 4. Apparatus according to claim 1, c h a r a c¬ t e r i z e d in that the protective casing (10) is attached to a housing (6) surrounding the apparatus and arranged to extend substantially from the central line of the inlet (5) of the pressure feeding means (1) close to the lower end of the apparatus, the protective casing preventing the scoops (9) from sticking to the powdery material when they move downwards with respect to the operating position of the apparatus.

Inventors: YLAEMAEKI JOUKO, YLAEMAEKI, JOUKO
Applicants: KOTERA ENGINEERING OY
Application year: 1991
Main classification: B65G53
IPC codes: B65G53