METHOD AND APPARATUS FOR CONVEYING PARTICULATE MATERIAL

Abstract: Apparatus for conveying particulate material, for inst­ ance, dust or coal in lump form, includes a plurality of inlet chambers (4) to a common conveying conduit (7), means (1, 2) for feeding particulate material to the inlet chambers, each inlet having associated therewith a valve (5) to allow or shut off flow of material to the inlet. Means (21,11,6) are provided for feeding pressurised gas to the apparatus to propel the particulate material through the conduit. Operating means are provided for simultaneously or sequentially opening the valves to allow the inlets to be filled simultaneously or sequentially with particulate material and for subsequently closing the valves, and for causing pressurised gas to be applied to the apparatus to propel material through the conduit.

Description: DONVEYING SYSTEMS This invention relates to conveying systems and in particular to systems for conveying particulate material along a pipe. According to the present invention apparatus for conveying particulate material comprises a plurality of inlets to a common conveying conduit, means for feeding particulate material to said inlets, each inlet having associated therewith a valve to allow or shut off flow of material to said inlet and means for feeding pressurised gas to the apparatus to propel particulate material through said conduit, and operating means for simultaneously opening the valves to allow the inlets to be filled simultaneously with particulate material, subsequently closing the valves and for causing pressurised gas to be applied to the apparatus to propel material through the conduit. The present invention makes use of a dense or medium phase pneumatic conveying technique and may be applied, for example, to the conveying of dust collected in large electrostatic or bag type air filters such as those used in power stationsandprocess plants. Because of the large physical size of these filter units the dust is collected in a large number, for example, forty, dust collecting hoppers fitted beneath the filter system. Known methods.of collecting this dust at one central point for disposal processing include: a) Hydraulic sluicing systems where high pressure water is sluiced through open channels, the dust being fed from the collection points through rotary discharge valves into the water stream, the water being discharged into settling ponds; b) Drag link or enmasse conveyors collecting from a line of discharge points into other conveyors or into pneumatic transport systems; c) Vacuum collection from each discharge point involving high velocity lean phase conveying which causes conveying pipe andbendcorrosion; d) A separate pneumatic conveying vessel connected to each discharge point and being connected to a common conveying pipe, each vessel working at a different time, pipeline valves being fitted in the conveying pipe to prevent material flow into those vessels not operating through the common conveying pipe. Another applicaton of the present invention is for conveying lump coal of the type used in industrial boilers. The coal may contain a high moisture content making the coal cohesive. Known methods of moving coal from a plurality of points on one large storage bunker include mechanical devices such as belt conveyors, en-masse- conveyors and screw conveyors. A particular application may be the conveying of coal on coal fired ships and an advantage of the present invention is that the system can easily be made totally sealed, water and dust tight and fully automatic. Furthermore, apparatus in accordance with the present invention is also relatively small and can withstand water flooding of the bunkers should a fire occur. In apparatus aaccording to the present invention pressurised gas may be fed to the inlets and it may be fed to the first of the inlets or to more than one of said inlets. The inlets may be in the form of chambers each communicating with the conduit. In an alternative embodiment in accordance with the present invention the valves are open sequentially to fill the inlets. The pressurised gas may be supplied sequentially to the chambers moving material from a first chamber before applying gas to the next successive chamber. The present invention also provides a method for conveying particulate material along a conduit, said method. including feeding material into a plurality of conduit inlets via valves, said valves being opened simultaneously or sequentially, closing said valves and applying pressurised gas to the conveying system in order to move particulate material along the conduit. An embodiment of the present invention will now be described, by way of example only, and with reference to the accompanying drawing, which illustrates apparatus in accordance with the present invention. Referring to the drawing, apparatus in accordance with the present invention includes a storage hopper 1 having four outlets 2. Particulate material located in storage hopper 1 collects or is stored in all of the conical shaped hoppers above the conveying chambers 4. Each conveying chamber is surmounted by a closure member 5, for example, a closure member having a part-spherical or dome-shaped valve member similar to that described in U.K. Patent Specification No. 1,539,079, which valve member is capable of cutting through a static column of particulate material and forming an air-tight seal. Pressurised air is supplied from source 21. It can be supplied directly to conveying pipe 7 through valve 6. It can also be supplied to each of the conveying chambers by valves 7. Each conveying chamber 4 leads into conveying pipe 7. The vessels are so constructed as to allow the passage of particulate material from one vessel through another vessel without obstruction. Conveying pipe 7 leads into conveying pipe 8 which in turn leads to material receiving hopper 9. Hopper 9 is fitted with a filter unit 10 to allow the conveying air to escape without carrying dust with it. The start of the conveying sequence can be initiated either by material level controls in the hoppers or by time sequence.Atthe start of the sequence of operations the conveying chambers 4 and pipework 7 and 8 are empty, air valve 6 is closed and valves 5 are closed. Operating means (not shown) open valves 5 simultaneously for a pre-determined time period allowing all the chambers 4 to fill with particulate material. Valves 5 are closed and sealed and air valve 6 opens pressurising the vessel 4 nearest to valve 6. The air in conveying pipe 7 is compressed by the movement of material/air in the fist chamber and this causes the material in the second chamber to move and so on until the complete material mass in the vessels is transferred throuah - - / ¯¯thevconveying pipe 8 to hopper 9. When all the material has reached hopper 9, valye 6 closes and the system is now ready to begin another conveying cycle. Where the materials being conveyed are cohesive, it may be necessary to apply air into all of the conveying chambers and through valves 11 simultaneously with the operation of valve 6 in order to encourage material movement into the conveying pipe. Alternatively, valves 11 may be operated sequentially starting with the first chamber (that closest to valve 6). When the material in the first chamber is moved into the conveying pipe, air is applied to the next successive chamber and so on until all the material is being conveyed. With some particulate materials, it would be necessary to allow the chambers to fill with material sequentially starting with the one nearest to valve 6 so that the displaced air can escape down conveying conduit 8 before the next chamber is filled and so on until all the chambers are full. An advantage of the present invention is that it allows conveying chambers of small height to be used to transfer high tonnage rates from multiple discharging points into a common conveying pipe.

Claims: CLAIMS: 1. Apparatus for conveying particulate material characterised in that the apparatus comprises a plurality of inlets to a common conveying conduit, means for feeding particulate material to said inlets, each inlet having associated therewith a valve to allow or shut off flow of material to said inlet and means for feeding pressurised gas to the apparatus to propel particulate material through said conduit, and operating means for simultaneously or sequentially opening the valves to allow the inlets to be filled simultaneously or sequentially with particulate material and subsequently closing the valves, and for causing pressurised gas to be applied to the apparatus to propel material through the conduit. 2. Apparatus according to claim 1 characterised in that the operating means are such as to supply pressurised gas sequentially to the inlets whereby material is moved from one inlet before gas is applied to the next successive inlet. 3. A method for conveying particulate material along a conduit characterised in that the method includes feeding material into a plurality of conduit inlets via valves, said valves being opened simultaneously or sequentially, closing said valves and applying pressurised gas to the conveying system in order to move particulate material along the conduit.

Inventors: SNOWDON, BRIAN
Applicants: MACAWBER ENGINEERING LIMITED
Application year: 1982
Main classification: B65G53
IPC codes: F23K3, B65G53, F23J3