US 3366282 A
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Description (OCR text may contain errors)
Jan. 30, 1968 2 Sheets-Sheet 1 Filed April 25, 1966 INVENTOR Doueus H. Lucas ATTORNEYS D. H. LUCAS GRANULAR FLOW STIMULATING DEVICES Jan. 30, 1968 Filed April 25, 1966 2 Sheets-Sheet um! I mu INvEN-rQR DoueLAs H. Lucas United States Patent Ofifice 3,366,282 GRANULAR FLOW STIMULATING DEVICES Douglas Harold Lucas, Beneath the Bough, 38 Lodge Close, Stoke dAbernon, Cobham, England Filed Apr. 25, 1966, Ser. No. 544,968 Claims. (Cl. 222-195) ABSTRACT OF THE DISCLOSURE In a container for granular material such as coal a flow stimulating device is provided. This device comprises an elongated tube mounted for movement adjacent to and parallel with at least a part of the interior wall surface of the container. The tube has a plurality of apertures through which compressed air is blown. Means is provided for maintaining the apertures in a direction such that the compressed air is blown in directions substantially parallel with the interior surface of the container to stimulate flow adjacent the surface.
This invention relates to the stimulation of the flow of granular material, for example flow under the influence of gravity, in a container for the granular material and is particularly, though not exclusively, applicable to stimulating the gravity flow of coal from a container such as a bunker or hopper.
It has already been proposed to inject compressed air into a container for granular material through nozzles projecting through the container walls into the interior of the container. However, these nozzles are stationary and the eifect of the compressed air is restricted to the vicinity of the outlets. If flow of the granular material is to be maintained throughout the bunker a very large number of nozzles will be necessary and large volumes of compressed air will be required. Thus the prior system is inefficient and expensive.
According to the present invention a container for granular material is in combination with a flow stimulating device comprising an elongated member, admission means for admitting pressurized gas to the interior of the elongated member, the elongated member having a number of longitudinally spaced laterally directed apertures for the emission of compressed gas into granular material in the container, the elongated member being mounted on the container by mounting means permitting movement of the elongated member about the interior of the container.
In most embodiments there will be a number of longitudinally spaced apertures in the elongated member.
The flow stimulating device may include means for delivering blasts of compressed gas through the apertures in sequence. Thus there may he means for opening and closing the apertures in sequence. The device may be connected to a supply of compressed air at substantially constant pressure and the means for opening and closing the apertures may be used as the sole means for controlling the emission of gas. In an alternative arrangement the escape of compressed air may be controlled additionally or solely by valve means adapted to permit compressed gas to flow through it in short blasts. The means for opening and closing the apertures in sequence will then act chiefly or solely to determine which of the apertures is to be used for the escape of gas when the valve means releases a blast of compressed gas.
The device may be controlled by a timing mechanism which causes the device to operate for a short period of time at fairly long intervals of time and there may also be provided an emergency device which causes the device to operate at any other time if the flow of material from the container fails or falls below a certain figure.
Patented Jan. 30, 1968 In one form, the mounting means permits the elongated member to traverse around the interior surface of the container parallel to and close to this surface, but the mounting means may permit movement of the elongated member over substantially the whole of the interior of the container. One suitable arrangement permitting such movement is constituted by a travelling gantry arrangement to which the upper end of the elongated member is attached. Alternatively, the mounting means may limit movement of the elongated member to traversing around or across the interior surfiace of the container. A possible form of such mounting means comprises a rail which extends around the container and on which the elongated member is carried.
The invention may be performed in various ways and a number of embodiments will now be described by way of example with reference to the accompanying drawings in which:
FIGURE 1 is a diagrammatic cross-section through a rectangular bunker in which is mounted a flow stimulating device;
FIGURE 2 is a fragmentary front view to a larger scale of the tubes of the flow stimulating device shown in FIGURE 1;
FIGURE 3 is a fragmentary side view of the tubes shown in FIGURE 2;
FIGURE 4 is a fragmentary sectional view to a further enlarged scale of the lower part of the tubes shown in FIGURES 2 and 3;
FIGURE 5 is a diagrammatic cross-section through another rectangular bunker;
FIGURE 6 is a fragmentary section to a larger scale on the line A-A in FIGURE 5;
FIGURE 7 is a fragmentary section to a further enlarged scale on the line BB in FIGURE 6; and
FIGURE 8 is a diagrammatic cross-section through a circular bunker.
Referring now to FIGURES 1 to 4 of the drawings, there is shown a rectangular bunker 1 containing granular coal 2 which flows under gravity through an opening 3 at the bottom of the bunker. Each end of the bunker is provided with a rail 4 on which is mounted a gantry 5 which extends the length of the bunker and can be moved from side to side of the bunker on wheels 6 which run on the rails 4.
Mounted on the gantry 5 by wheels 7 is a carriage 8 which can be moved from end to end of the gantry. Thus the carriage 8 can be positioned above any part of the bunker. Carried on gimbal mountings on the carriage 8 is a granular flow stimulating device 9 which includes an outer tube 10 and an inner tube 11 which is mounted for reciprocation within the outer tube. The outer tube is provided with a number of downwardly inclined short pipes 12 arranged in oppositely disposed pairs, the pipes being formed as nozzles as can be seen from FIGURE 4. The pipes are in communication with the interior of the outer tube 10 through holes 13.
The inner tube 11 has a number of pairs of openings 14 corresponding to the holes 13 in the outer tube although, as will be seen from FIGURES 2 and 3, their spacing is slightly different.
The carriage 8 supports a geared electric motor 20 which drives a screw 21 which passes through an internally threaded cap 22 at the upper end of the inner tube 11. When the motor 20 is rotated in one direction the inner tube 22 will be raised relative to the outer tube and when the motor is rotated in the opposite direction the inner tube will be lowered relative to the outer tube. Limit switches, which are not shown, are provided for reversing the motor at the end of travel of the inner tube so that the inner tube is reciprocated within the outer tube.
The inner tube is in communication through a flexible 3 tube 25 with a compressed air main 26 the outlet from which contains a solenoid-operated valve 27.
When stimulation of the flow of the coal in the bunker is required, the solenoid-operated valve 27 is opened to admit compressed air to the interior of the inner tube 11 and the motor is switched on to reciprocate the inner tube. In the relative positions of the two tubes shown in FIGURES 2, 3 and 4, jets of air will be emitted through the lowermost pair of pipes 12. As the inner tube moves upwardly the supply of air to the lowermost pair of pipes 12 will be cut off and compressed air will then be emitted from the pair of pipes immediately above the lowermost pair. During the upward travel of the inner tube gas will be emitted in succession from the pairs of pipes 12 and the reverse will occur as the inner tube moves downwardly. In order to stimulate the flow of coal throughout the bunker, the stimulator is preferably moved along parallel to and close to the sides of the bunker and the lower end of the stimulating device is kept out of contact with the internal surface of the bunker by projections 28 on the lower end of the outer tube 10. Automatic means may be provided for traversing the stimulating device over the surface of the bunker and for rotating the inner and outer tubes through 90 at each corner of the bunker so that the blasts of air emitted through the pipes 12 will be parallel to the adjacent surface of the bunker. There may also be occasions, for example when compacted coal has formed a thick layer on the walls of the bunker, when the stimulator is best operated close to the centre of the bunker in the position shown in FIGURE 1.
In an alternative mode of operation the valve 27 is synchronized with the movement of the inner tube 11 so as to be opened only when a pair of apertures 13 and 14 are fully open. Thus the inner tube acts chiefly to select the apertures in the outer tube through which blasts of compressed air controlled by the valve 27 are emitted.
As shown in FIGURE 4, flanges 3t and 31 extend around the circumference of the inner tube immediately above and immediately below each pair of apertures 14 in order to restrict the loss of gas between the inner and outer pipes.
Various modifications to the construction described may be made, and a number of these will now be briefly described. Instead of the traversing arrangement comprising rails at each end and a gantry carrying a carriage, the stimulating device may be carried on a single rail which extends all round the bunker. This construction is particularly suitable for bunkers of circular section. The flow stimulating device may be constructed so that it may be moved from bunker to bunker as required. It is not necessary for the inner tubes to be continuous and a possible construction is for the inner tube to be made up of a number of hort sections, each section being in the vicinity of a hole or holes in the outer tube, and connecting pieces extending between adjacent sections. In place of the electrical reciprocating means described, hydraulic means comprising a double-acting piston could be adopted. A compressed air reservoir may be provided adjacent the stimulating device to provide a store of compressed air to maintain the energy of the blasts of gas emitted through the holes, if a flexible pipe of relatively small bore is used to supply compressed gas.
The bunker shown in FIGURE 5 is of rectangular crosssection and is built from steel plate. The bunker contains granular coal 42 which falls under gravity through an opening 43 at the bottom of the bunker. One end wall of the bunker, which is viewed in elevation in FIGURE 5, has a flow stimulating device 44 which comprises a tube 45 which is closed at one end 46 and has a right-angled bend 47 at the other end leading to a short straight section 48 which projects through an aperture 49 in the end wall of the bunker. The aperture 49 is closed by a mounting plate 51 secured to the bunker wall by screws 52. The plate 51 carries a bearing 53 in which the tube section 48 can rotate about an axis 54 which is perpendicular to the end wall of the bunker. Fixed to the pipe section 48 is a Worm wheel 55 meshing with a worm 56 driven through a reduction gear box by an electric motor 57 mounted on the end wall of the bunker. At the outer end of the pipe section 48 is a stufling gland 58 which connects the rotatable pipe section 48 with the end of a stationary pipe 59 through which compressed air may be supplied to the rotatable pipe.
The tube 45 carries a number of nozzles 61 which can be seen in more detail in FIGURE 7. Each nozzle 61 projects through the wall of the tube 45 from a solenoid operated valve 62 having a control solenoid 63 and an inlet 64 which is open to the interior of the pipe 45. As the solenoid operated valve is a common article of commerce it will not be described in detail. The solenoid can be actuated through leads 65 which extend along the length of the tube 45 and pass out of the stationary pipe 59 through a seal 66 to a switch control system not shown.
The operation of the apparatus shown in FIGURES 5 to 7 is as follows. Compressed air is supplied through the stationary pipe 59 to the pipe 45, which, in normal opera tion of the bunker, is stationary with all the solenoid operated valves 62 closed. At predetermined intervals of time, or when a blockage is suspected, the electric motor 57 is energised and the tube 45 is caused to oscillate through a sector indicated by the chain-dotted line 67 in FIGURE 5. The solenoid operated valves 62 are opened in a sequence controlled by the switching system, each valve being opened for short periods of time during which strong bursts of air are blown into the bunker. It will be seen from FIGURE 5 that substantially the whole of the end face of the bunker will be subjected to transverse bursts of air as the pipe 45 traverses the face. A similar granular flow stimulating device will be provided on the bunker face opposite to that visible in elevation in FIGURE 5 and similar devices may also be provided on the other two faces if required.
The axis of rotation 54 may alternatively be located at various other points on the end face of the bunker. For example, the axis may pass approximately through the centre of the face and in this case the tube 45, which will be shorter than that shown in FIGURE 5, may rotate through 360 about the axis instead of oscillating through a short are. In another possible arrangement the axis 54 is adjacent the mouth of the opening 43 and the tube 45 extends upwardly and oscillates between end positions in which it lies parallel with the two side Walls of the bunker.
The bunker shown in FIGURE 8 is generally conical, the inner surface of the bunker being generated by a straight line about an axis 72. The bunker 71 has an outlet 73 which is slightly eccentric to the axis 72. A granular flow stimulating device 74 comprises a tube 75 having a bend 76 and a short straight section 77 co-axial with the axis 72 of the bunker. The section 77 extends into a housing 78 which contains mounting means, driving means and connecting means similar to those shown in FIGURE 6. The upper end of the tube 75 carries a roller 79 engaged with the inner face of the bunker. In operation the granular flow stimulating device 74 rotates about the axis 72 and thus traverses the inner surface of the bunker wall. During this time bursts of air are admitted to the bunker through nozzles 81 along the length of the tube 75.
What I claim as my invention and desire to secure by Letters Patent is:
1. In a container for granular material having a flow stimulating device comprising an elongated member and admission means for admitting compressed gas to the interior of the elongated member, the elongated member having a number of longitudinally spaced apertures for the emission of compressed gas into granular material in the container, the improvement comprising mounting means by which the elongated member is mounted on the container, said mounting means comprising means permitting movement of the elongated member along a path adjacent to and parallel with at least a part of the interior wall surface of the container, and means for maintaining said apertures oriented to direct said compressed gas in directions substantially parallel with said surface.
2. A container as claimed in claim 1 in which the flow stimulating device includes means for controlling the delivery of compressed gas through the apertures whereby compressed gas is delivered through the apertures in sequence.
3. A container as claimed in claim 1 including valve means in the compressed gas admission means adapted to permit compressed gas to flow through it in short blasts.
4. A container as claimed in claim 1 in which each aperture has a solenoid-operated valve housed within the elongated member.
5. A container as claimed in claim 1 in which the means permitting movement of the elongated member permits movement about substantially the entire interior Wall surface of the container.
6. A container as claimed in claim 5 in which the mounting means is constituted by a travelling gantry arrangement to which the upper end of the elongated member is attached.
7. A container as claimed in claim 1 in which the elongated member has a pipe section at one end which is at an angle "to the longitudinal axis of the elongated member and is rotatably mounted in a fixed support on the container.
8. A container as claimed in claim 7 in which the pipe section is normal to the longitudinal axis of the elongated member and to the part of the interior wall surface of the container in the vicinity of the fixed support.
9. A container as claimed in claim 7 in which the interior wall surface of the container is a surface of revolution, the pipe section being coaxial with the axis of generation of the surface and the elongated member being parallel with a generatrix of the surface.
10. A container for granular material and a flow stimulating device as claimed in claim 7 in which each aperture has a solenoid-operated valve housed Within the elongated member.
References Cited UNITED STATES PATENTS 3,166,222 1/1965 Schrader 222- FOREIGN PATENTS 468,567 7/ 1937 Great Britain.
ROBERT B. REEVES, Primary Examiner.
F. R. HANDREN, Assistant Examiner.