EP1704930A2

EP1704930A2 - Grid arrangement

Info

Publication number: EP1704930A2
Application number: EP06251498A
Authority: EP
Inventors: Robin Clive Travis
Original assignee: Renby Ltd
Current assignee: Renby Ltd
Priority date: 2005-03-24
Filing date: 2006-03-21
Publication date: 2006-09-27
Also published as: GB0506068D0; EP1704930A3

Abstract

A self-cleaning grid arrangement (11, 19) is provided for use in bulk materials handling, e.g. quarry, chemical, waste or recycling industries during the conveyance of particulate material to prevent the passage of oversize particles or foreign objects to the destination of the particulate material. The grid arrangement (11) is formed of a first set bars (12) disposed substantially parallel with each other, the bars (12) extending between and being supported in holes (14, 21) in the sides (13, 22) of a chute (10) in which the bars (12) are free to rotate and/or reciprocate lengthways. At least some of the bars (12) have disturber plates (31) extending upwardly therefrom spaced along their length. As a result of such rotation and/or reciprocation, if particulate material does stick to or coagulate above a bar (12), there will be a lesser tendency for any material to bridge to an adjacent bar (12) and an increased tendency for the particulate material to fall between the bars (12). The bars (12) are curved along their length and have a radius of curvature greater than the length of the bars (12) between the sides (13). Each bar (12) has one end (16) depending from the remainder of the bar (12) in the direction away from the centre of curvature of the bar (12). A second set (19) of bars (20) that are substantially parallel with each other, is disposed substantially at right angles to the first set of bars (12). The bars (12, 20) may be inclined, and bars (26) may be tapered towards their lower ends. The support structure for the bars (12, 20) has inner (13) and outer (32) side plates so that particulate material passing through the holes (14) in the inner side plates (13) pass through a passageway (33) between the side plates (13) and outer side plates (32) and are returned to the lower part 28 of the chute (10).

Description

This invention relates to a grid arrangement, and in particular to a grid arrangement for use in the path of conveyance of particulate material. One particular application is in the filling of bags with particulate material using a chute from a hopper containing the material.
Grid arrangements are used in the quarry, chemical, food, waste and recycling industries during the conveyance of particulate material for preventing the passage of oversize particles or foreign objects to the destination of the particulate material. Typical materials for which such grid arrangements are used are fluorspar, sand, rubber crumb and the like. Such grid arrangements usually comprise a parallel arrangement of bars disposed across a chute or other form of passageway down or through which the particulate material is passed. A second parallel arrangement of bars disposed at right angles to the first arrangement may be provided such that the two arrangements form a lattice. Alternatively a wire mesh arrangement may be used. The spacing of the bars or mesh size dictates the size of the particles or objects retained by the grid arrangement. The bars or mesh may be welded or the bars screwed into side plates to form an integral structure that may be removed from the chute or passageway for cleaning purposes. However, many of the materials for which such grid arrangements are used tend to stick to the bars or mesh, particularly when the materials are damp. This often results in bridging of the bars or mesh by the particulate material, thereby preventing further passage of the material through the bars or mesh. In consequence, frequent cleaning may be required if the passage of the particulate material is to proceed satisfactorily. This is an undesirable task, and can result in considerable downtime of the process equipment. In order to overcome the problems outlined above, it has been disclosed in GB 2379433 to provide a grid arrangement in which spaced parallel bars are each rotatable in the supporting side plate structure in which they are mounted. This rotation disturbs the particulate material and reduces the tendency for the material to adhere to the bars. The bars are curved along their length. Despite such an arrangement being an improvement on previously known arrangements, some particulate materials still have a tendency to coagulate above the bars thereby preventing the material from passing between the bars despite their disturbing motion.
It is an object of the present invention to provide a grid arrangement that minimises the above problems of coagulation thereby maintaining the requirement for frequent maintenance and cleaning.
The invention provides a grid arrangement disposed in a passageway for the conveyance of particulate material, comprising a plurality of bars disposed substantially parallel with each other, the bars being mounted in a support structure and extending across the passageway, the bars being free to move relative to the support structure, characterised in that at least some of the bars have disturber members extending upwardly therefrom spaced along their length.
The disturber members also extend downwardly from the bars. Each of the bars may have upwardly extending disturber members spaced along its length. The disturber members may be fixedly mounted on the bars, or may be free to rotate on the bars. The disturber members may comprise plates. Each bar may be rotatably mounted in the support structure. The bars may be curved along their length, having a radius of curvature greater than the length of the bars between the support structure. The radius of curvature may be at least six times the length of the bars between the support structure. Each bar may have a bend in the region of one end thereof to form an end region that in use depends from the remainder of the bar. The end region may depend in the direction away from the centre of curvature of the bar. An actuator may be coupled to at least some of the bars to rotate them, preferably to at least alternate bars.
Each bar may be reciprocable lengthways of itself in the support structure, and the grid arrangement may comprise actuating means operable to move the bars in a rotary or lengthways reciprocating motion. The actuating means may comprise a pneumatic actuator. The support structure may comprise opposed side plates. The bars may pass through holes in the support structure that are oversize relative to the cross-sectional dimensions of the bars. The support structure may comprise opposed outer side plates through which the bars also pass. The passageway between the side plates and the outer side plates may communicate beneath the bars with the passageway between the side plates.
The grid arrangement may comprise a second plurality of bars disposed substantially parallel with each other and beneath and substantially at right angles to the first plurality of bars. The second plurality of bars may be free to move relative to the support structure. At least some of the second plurality of bars may have disturber members extending upwardly therefrom spaced along their length. Each of the second plurality of bars may have upwardly extending disturber members spaced along its length. The disturber members may comprise plates. Each bar of the second plurality of bars may be rotatably mounted in the support structure. Each bar of the second plurality of bars may be reciprocable lengthways of itself in the support structure, and the grid arrangement may comprise second reciprocating means operable to move the bars of the second plurality of bars in a reciprocating motion. The second reciprocating means may comprise a second pneumatic actuator.
Each plurality of bars may be supported in respective holes disposed along a line that is substantially parallel with the bars of the other plurality of bars. If the bars are curved, each plurality of bars may be supported in respective holes disposed along a curved line that is substantially parallel with the curved bars of the other plurality of bars.
The bars may be disposed to extend horizontally between the support structure. Alternatively, the bars may be inclined. An access opening to the lower end of the bars may be provided in the support structure. Alternatively, the bars may be tapered towards their lower ends. The grid arrangement may comprise separate receptacles for particles passing between the bars at the upper and lower ends thereof. Each bar may have a circular cross-section, or at least between the side plates may have a wedge section. The bars may be of stainless steel.
The invention will now be described with reference to the accompanying drawings in which:

Fig. 1 is a cross-section of a chute with a first embodiment of grid arrangement,
Fig. 2 is an underplan of the embodiment of Fig. 1,
Fig. 3 is a cross-section of a chute with a second embodiment of grid arrangement,
Fig. 4 is an underplan of the embodiment of Fig. 3,
Fig. 5 is a cross-section through an alternative bar
Fig. 6 is a cross-section of a chute with a third embodiment of grid arrangement, and
Fig. 7 is a plan view of a fourth embodiment.

Referring now to Figs. 1 and 2, there is shown a passageway in the form of a chute 10 down which particulate material is passed from a hopper (not shown) to a destination (not shown). The means to supply the particulate material and/or the destination may be, for example, a bag filled or to be filled with the particulate material or a vehicle for transporting the material from or to another location. Such a vehicle may be a moving floor lorry, trailer or container, e.g. a Walking Floor (Trade Mark) vehicle. To prevent the passage of oversize particles or foreign bodies, a grid arrangement 11 is installed in the chute 10, which forms a support structure for the grid arrangement 11. The grid arrangement consists of an array of bars 12a, 12b in parallel disposition extending across the chute 10. The bars 12a, 12b extend between side plates 13, which in the embodiment shown are part of the chute 10. However, the plates 13 may be a separate support structure attached to the walls of the chute 10 if preferred. The bars 12a, 12b are of stainless steel to inhibit rusting and to minimise the tendency of the particulate material to stick to the bars 12a, 12b. However, the bars 12a, 12b may be of other suitable wear resistant materials, for example corrosion protected mild steel, dependent on the particulate material involved, if preferred. The bars 12a, 12b are of circular cross-section and pass through holes 14 that are oversize relative to the diameter of the bars 12a, 12b so that the bars 12a, 12b are free to move in the plates 13. However, such oversize is less than the spacing of the bars 12a, 12b so that oversize material does not escape through the holes 14. Such movement may be rotation and/or reciprocation lengthways of the bars 12a, 12b. In consequence, if particulate material does stick to a bar 12a, 12b, there will be a tendency for that bar to rotate or it may be reciprocated or both, thereby breaking any tendency for the material to bridge to an adjacent bar 12a, 12b and increasing the tendency for the particulate material to fall from the bars 12a, 12b. The tendency for the bars 12a, 12b to rotate is enhanced by two factors. Firstly, each bar 12a, 12b is curved along its length, at least along that length extending across the chute 10 between the side plates 13. The radius of curvature is greater than the length of the bars 12a, 12b between the side plates 13, and preferably is about six times that length. Thus, if a bar 12a, 12b is displaced from the undisturbed disposition shown in Fig. 1, it will tend to rotate back to that disposition due to the offset weight of the centre portion of the bar 12a, 12b. Secondly, each bar 12a has a bend 15 in the region of one end to form an end region 16 that will tend to hang vertically downwards due to its weight. The end region 16 extends in the direction away from the centre of curvature of the bar 12a so that the curvature of the bar 12a and the depending end region 16 create the same disposition restoring effect to the bar 12a. As an alternative, or in addition, the bars 12a may be readily agitated by hand using the free end region as a "handle". Reciprocation of the bars 12b to dislodge particularly sticky material is effected by an actuator 30, preferably a pneumatic actuator, acting on an actuating rod 18 coupled to the ends of bars 12b. The actuator 30 may be a motor or an electrical, pneumatic or hydraulic actuator. At least some of the bars 12, in this case alternate bars 12b, have upwardly extending disturber members 31 spaced along their length. If preferred, each bar 12a, 12b may have the disturber members 31 spaced along its length. Each disturber member 31 comprises a plate secured, for example by welding, to the bar 12b, and serves to disturb, due to the movement of the bars 12b, any sticky particulate material that has coagulated above the bars 12a, 12b. Alternatively, the disturber members 31 may be free to rotate on the bars 12. The reciprocating movement of the bars 12b and the disturber plates 31 increase the tendency for fine particulate material to penetrate the holes 14 to the outside of the support plates 13. To overcome this problem, the support structure is provided with outer side plates 32 through which the bars 12 also pass. The passageway 33 formed between the side plates 13 and the outer side plates 32 communicates beneath the bars 12 with the passageway 34 between the side plates 13 to form a single passageway 28 in the lower part of the chute 10. This ensures that any particulate material that passes through the holes 14 passes to the correct destination down the chute 10. The end regions 16 of bars 12a depend in this region 33 so that any particulate material passing through the holes 14 onto the end regions 16 cannot pass through the outer side plates 32.
In an alternative arrangement to that shown in Figs. 1 and 2, all of the bars 12 may have the form of bars 12b described above, with disturber plates 31 attached thereto so that a substantially complete lattice formation is formed when looked in plan view (see Fig. 7). With this arrangement, all of the bars 12 are reciprocated by the actuator 30.
Referring now to Figs. 3 and 4, there is shown an alternative grid arrangement 19. Many of the parts shown in Figs. 3 and 4 are identical with the corresponding parts of the grid arrangement 11 and are identified by the same reference numerals. In this second embodiment, there is provided a second array of bars 20 that extend parallel with each other across the chute 10 at right angles to the bars 12. This provides a mesh type of arrangement of the bars 12, 20 when viewed in under plan as in Fig. 4. To maintain a substantially constant spacing between the bars 20 and the bars 12, the centres of the holes 21 in side plates 22 in which the bars 20 are supported lie on a line that is curved to the same curvature as that of the bars 12. Similarly, the centres of the holes through which bars 12 pass lie on a line that is curved to the same curvature as that of the bars 20. In this case, both the upper bars 12 and the lower bars 20 have the upwardly extending disturber plates 31 spaced therealong. However, only the upper bars 12 may have the disturber plates 31 if desired. Outer side plates 35 through which the bars 20 also pass are provided, particularly if, as shown, lower bars 20 have disturber plates 31 thereon.
As an alternative to the bars 12 being disposed in a horizontal plane across the chute 10, they may lie in an inclined plane as shown in Fig 6. In this case, the bars 12 are shown fitted with an alternative form of disturber plate 31, which also extends downwardly from the bars 12 thereby providing a weighted lower part to increase the tendency for the bars 12 to return to the undisturbed position after any disturbance therefrom. With such an arrangement, oversize particles may roll or slide to the lower bars 12. These oversize particles may then be removed through an access opening 25 to one side of the chute 10. Particle size or product separation may also be achieved by an arrangement as shown in Fig. 7. In this case, the bars 26 are tapered towards their lower ends so that the gap between them increases towards their lower ends. By this means, larger particles may pass between the bars 26 only at their lower ends down an auxiliary chute 27 separate from the main part 34 and the lower part 28 of the chute 10. The bars 12, 20, 26 may be of non-circular cross-section, at least in the part extending across the chute 10, such as the wedge shape of the bar 23 shown in Fig. 5. Such a section will have an enhanced effect of breaking coagulated or oversize particles and any particles adhering to the sides 24 of the bar 23 will cause rotation to the bar 23 to inhibit bridging of the material to an adjacent bar 23. Other sections of bar 12, 20, 23, 26 such as elliptical or polygonal may be used if preferred. Also, the shape of the disturber plate 31 may be rectangular, elliptical or any other suitable shape, as desired.
Individual bars 12, 20, 23, 26 may be readily removed from the chute 10 if necessary for cleaning or replacement when worn, thereby avoiding the need to open the chute 10 or remove and possibly replace the entire grid arrangement 11, 19. Thus cleaning, which is required less frequently with the grid arrangement 11 or 19, due to its self-cleaning effect, than was the case with prior known grid arrangements, is less onerous and involves less downtime than was previously the case. Also replacement of a single bar 12, 20, 23, 26 if worn or damaged is less costly than replacement of an entire grid arrangement of previously known type. In the figures, the grid arrangements 11, 19 are shown at a location below the top of the chute 10. However, in appropriate circumstances, the grid arrangement may be disposed at either the top or the bottom of the chute or on top of a receiving hopper or the like.

Claims

A grid arrangement disposed in a passageway for the conveyance of particulate material, comprising a plurality of bars disposed substantially parallel with each other, the bars being mounted in a support structure and extending across the passageway, the bars being free to move relative to the support structure, characterised in that at least some of the bars have disturber members extending upwardly therefrom spaced along their length.
A grid arrangement as claimed in claim 1, characterised in that the disturber members also extend downwardly from the bars.
A grid arrangement as claimed in claim 1 or claim 2, characterised in that the disturber members are fixedly mounted on the bars.
A grid arrangement as claimed in claim 1 or claim 2, characterised in that the disturber members are free to rotate on the bars.
A grid arrangement as claimed in any one of claims 1 to 4, characterised in that each bar is rotatably mounted in the support structure.
A grid arrangement as claimed in claim 5, characterised in that the bars are curved along their length.
A grid arrangement as claimed in claim 5 or claim 6, characterised in that at least some of the bars have a bend in the region of one end thereof to form an end region that in use depends from the remainder of the bar.
A grid arrangement as claimed in any one of claims 1 to 7, characterised in that at least some of the bars are reciprocable lengthways of themselves in the support structure.
A grid arrangement as claimed in claim 5 or claim 8, characterised by actuating means operable to move the bars in a rotary or lengthways reciprocating motion.
A grid arrangement as claimed in claim 7 or claim 8, characterised in that the support structure comprises opposed side plates through which the bars pass and the support structure also comprises opposed outer side plates.
A grid arrangement as claimed in claim 10, characterised in that a passageway between the side plates and the outer side plates communicates beneath the bars with the passageway between the side plates.
A grid arrangement as claimed in any one of claims 1 to 11, characterised by a second plurality of bars disposed substantially parallel with each other and beneath and substantially at right angles to the first plurality of bars.
A grid arrangement as claimed in claim 12, characterised in that the second plurality of bars is free to move relative to the support structure.
A grid arrangement as claimed in claim 13, characterised in that at least some of the second plurality of bars have disturber members extending upwardly therefrom spaced along their length.
A grid arrangement as claimed in any one of claims 12 to 14, characterised in that each plurality of bars is supported in respective holes in the support structure disposed along a line that is substantially parallel with the bars of the other plurality of bars.
A grid arrangement as claimed in any one of claims 1 to 15, characterised in that the bars are inclined.
A grid arrangement as claimed in claim 16, characterised in that an access opening to the lower end of the bars is provided in the support structure.
A grid arrangement as claimed in claim 16, characterised in that the bars are tapered towards their lower ends.
A grid arrangement as claimed in claim 17 or claim 18, characterised by separate receptacles for particles passing between the bars at the upper and lower ends thereof.
A grid arrangement substantially as hereinbefore described with reference to and as illustrated in Figs 1 and 2, or Figs 3 and 4, or Fig. 6 or Fig. 7 of the accompanying drawings.