GB2270683A

GB2270683A - Hopper dust containment filler.

Info

Publication number: GB2270683A
Application number: GB9319318A
Authority: GB
Inventors: Andrew Lettice
Original assignee: AAF Ltd
Current assignee: AAF Ltd
Priority date: 1992-09-17
Filing date: 1993-09-17
Publication date: 1994-03-23
Also published as: GB9219692D0; GB9319318D0

Abstract

A dust containment device for controlling emission from a container for particulate material is described. The device comprises at least one opening and a restrictor for the opening. The restrictor is formed from a baffle including a pair of baffle plates 8, 10, a first of which 8 is fixed in position and a second of which 10 is moveable relative the first between a first position in which the two plates cooperate to prevent egress of material from the container via the opening and a second position in which material can pass to the container via the opening. The second plate second plate is moved from the first to the second position as a result of loading thereof with particulate material. The moveable plate is suitably arranged to return to the first, closed, position under the influence of gravity alone after the passage of particulate material through the opening has ceased. The moveable baffle can be an elastic plate or a rigid hinged plate. <IMAGE>

Description

IMPROVEMENTS IN AND RELATING TO DUST CONTAINMENT SYSTEMS This invention relates to a dust containment device for use in connection with a process or plant in which particulate material is conveyed and/or received and/or stored. It has particular application to processes in which particulate materials are off-loaded into hoppers, whether alone or associated with track sinks, dump sinks, shoots or conveyors.

Off-loading of particulate materials often creates dust which must be restricted, retained and collected.

Dust creation is particularly bad when particulate material is discharged into a large open face area hopper due to the resultant turbulence within the hopper. In such a case, large volumes of dust-laden air needs to be controlled and attempts to do so by dust extraction alone would be extremely, if not prohibitively, expensive.

Dust restrictors are known which are in the form of shutters arranged in pairs. Each shutter is pivotally mounted at one edge thereof such that, when loaded by a particulate material, it can rotate against the bias of a spring from a closed position to an open position. A disadvantage of this arrangement is said to be that the shutters may be unreliable in operation because they rely entirely on the springs to close them.

A dust retention device has been suggested which is intended to overcome this problem. This comprises a plurality of restrictors, each of which consists of two plates fixed at an angle to each other such that the restrictor has an inverted V-shaped cross-section. Each restrictor is pivotal as a whole when the plates thereof are unevenly loaded from a closed position to an open position.

The suggested device also suffers from disadvantages due, at least in part, to the form of the restrictors thereof. Firstly, for a restrictor to move from the closed to open position, the plates thereof must be unevenly loaded and to ensure that this occurs, baffles have to be provided to direct falling particulate material to unequally load the plates of the restrictor. Secondly, the whole restrictor is swung clockwise or anticlockwise to move it from the closed to the open position. Depending on the weight of the restrictor, a significant amount of particulate material may need to fall thereon before it will move to the open position, which could create dust problems above the restrictors.Heavy bearings will be required and the outward or return swing of the restrictors could be such as to create turbulence in the hopper, thereby causing the dust problem to be worsened rather than improved.

In accordance with the invention, a dust containment device for a container for particulate material comprises at least one opening and a restrictor for the opening comprising a baffle including a pair of baffle plates, a first of which is fixed in position and a second of which is moveable relative the first between a first position in which the baffle prevents egress of material from the container via the opening and a second position in which material can pass to the container via the opening, loading of the second plate with particulate material causing movement thereof from the first to the second position.

Only one part of each baffle is moveable, the other part being fixed in position. The problems with the suggested arrangement described above where the whole restrictor has to move are, therefore, reduced and indeed may be completely obviated. Moreover, it is possible to arrange the plates so that the second moveable plate is returned to the closed position via the action of gravity alone, thus avoiding the problem found with the known arrangement described above.

In a particularly preferred embodiment, the first, fixed, plate of the baffle(s) is held at an angle to the axis of the opening such that it extends across part of the opening. The second, moveable, plate is moveable between the first position in which it lies generally parallel to the axis of the opening and the second position in which it is generally parallel to the first, fixed, plate. The two plates are mounted relative each other so that, with the second, moveable, plate in the first position thereof, they together define a sawtooth shape.

The first plate provides a permanent cover for the opening which will help prevent egress of dust therefrom, even when the second plate is moving between its two positions. The relative orientation of the two plates makes it possible for the second plate to be returned from the second position to the first position thereof by the action of gravity alone.

The second plate may, therefore, simply be pivotally mounted at one edge thereof such that the plate may pivot between the first and second positions.

The pivot mount of the second, moveable, plate may comprise any suitable hinge mechanism. For example a flexible strip formed of leather, plastic, or other appropriate material may be connected between the first, fixed, plate and the second, moveable, plate of each restrictor.

The second moveable plate may be rigid or flexible.

In the former case, suitable materials for the second plate, and in either case the first plate, include ferrous or non-ferrous metals or alloys, wood, marine ply, plastic or rubber or combinations thereof to provide the required rigidity, weight, abrasion and chemical resistance appropriate for the particulate material being handled. In the latter case, a continuous flexible member can form both the second plate and the pivot mount. The member may be constituted from rubber, plastic, fibres, textiles and metals or combinations thereof to provide the flexibility, weight, abrasion and chemical resistance appropriate for the particulate materials being handled. Depending on the material chosen, a further advantage of employing a flexible second member is that its elasticity will cause, or at least assist in, its movement to the closed position.

The pivot mounting may comprise a pivot pin secured to the frame and a sleeve surrounding the pin, which sleeve is attached to or integral with the second, moveable, plate. The advantage of the provision of a separate sleeve is that the plate can then be formed from any material, including those which are not suitable for forming part of a hinge mechanism.

The first, fixed, plate of the baffle(s) suitably has a flange along one edge thereof such that the plate is of inverted V-shaped cross-section with one arm of the Vshape comprising the plate itself and the other arm, which is relatively much shorter, comprising the flange. The pivot mounting of the second, moveable, plate is preferably positioned between the first, fixed, plate and the flange thereof. The mounting is thereby protected. The second moveable plate, in the first position thereof, can extend below the free edge of the flange with the result that the flange will help direct particulate material thereonto.

A plurality of restrictors may be provided arranged in at least one row of side-by-side baffles, each of which is suitably carried by a support frame. Part of the support frame of each restrictor may be common with that of the restrictor or restrictors adjacent thereto, so making for a simple and economical arrangement.

In the multiple-restrictor embodiment, the second, moveable, plate of each baffle in the or each row suitably extends between one edge of the first, fixed, plate of the baffle and an opposite edge of the first, fixed, plate of an adjacent baffle. With the first plates at an angle to, and the second plates aligned with, the axes of the openings, as in the preferred embodiment, the multiple baffles of the or each row will therefore generally define a sawtooth edge, broken by the flanges of the first fixed plates, if these are included. The first, fixed, plate of each baffle will direct particulate material onto the second, moveable, plate of an adjacent baffle. The flanges, if provided, will direct particulate material onto the first, fixed, plate of an adjacent baffle.

Thus, particulate material fed onto a multiplerestrictor device will be directed by the baffles themselves onto the moveable plates thereof which will, therefore, be caused to move to the open position so allowing ingress of the particulate material to the container via the opening. The fixed plates will substantially contain any dust which rises from the container during the feeding. Cessation of the feed of particulate material will result in the moveable plates returning to the first position thereof under the action of gravity, thus closing the openings.

The dust containment device may advantageously be employed to control dust flow through an access opening of a hopper or the like for containing particulate material, in particular, it may be positioned in a passage leading to the access opening. A dust extraction system may additionally be employed on a suitably located in-passage between the container and the device.

The invention will now be further described by way of example with reference to the accompanying drawings in which:- Figure 1 is a plan view of a dust containment device in accordance with the invention; Figure 2 is an enlarged sectional view taken along the line A-A of Figure 1; Figure 3 is an enlarged sectional view taken along the line B-B of Figure 1; Figure 4 is an enlarged view of the portion in Circle C of Figure 2; and Figure 5 is a similar view to Figure 4 but showing an alternative embodiment.

Figure 1 shows a dust containment device 2 comprising a single row of side-by-side restrictors 4 mounted in a passage 6 leading to a hopper, not shown.

Each restrictor 4 comprises a first, fixed, plate 8 and a second, moveable, plate 10. The first plate 8 is fixed at the end thereof to the longitudinal arms 12 of a frame which in turn is carried by the walls 13 of the passage 6. The frame additionally includes lateral crossmembers 14 extending between the longitudinal members 12 thereof.

The plate 8 of each restrictor is mounted to the longitudinal frame members 12 at an angle to the axis of the passage 6. This angle 15 may be, for example, 60".

The fixed plates 8 of the multiple-restrictors 4 in the device 2, therefore, together define a semi-continuous permanent cover across the passage 6.

Each fixed plate 8 includes an integral flange portion 16 at the upper edge thereof. The angle between the main body of the fixed plate 8 and the flange 16 may be, for example, 75".

A pivot pin 18 extends between the longitudinal members 12 of the frame below the flange 16 of each restrictor 4. Alternatively, two stub pins may be used, each attached to one of the longitudinal members 12. A collar 20 surrounds the pin and is attached to the moveable plate 10 of the restrictor 4. The hinge constituted by the pivot pin 18 and collar 20 allows the moveable plate 10 to pivot between two positions, a first position in which it hangs parallel to the axis of the passage 6 and a second position at an angle thereto in which it is generally parallel to the fixed plate 8. These positions are shown respectively in full outline and in dotted outline in Figure 4.

Figure 2 illustrates the operation of the dust containment device 2. Particulate material fed from above the device, see Arrow 22, falls onto the restrictors 4 and is directed by the angled plates 8 of each restrictor 4 onto the moveable plate 10 of the adjacent restrictor 4.

The flange 16 of each restrictor 4 directs particulate material onto the fixed plate 8 of the adjacent restrictor which in turn will direct it onto the moveable plate 10 of the restrictor 4. Rotation of the moveable plates 10 around the pivot pins 18 will open the restrictors 4 and the particulate material fed thereonto can pass into passage 6 and thence to the hopper.

When the feed of particulate material ceases, the moveable plates 10 of the restrictors 4 will rotate under the action of gravity back to the position thereof in which they are aligned with the axis of the passage 6 and extend between the free edge of the flange 16 of the associated fixed plate 8 and the lower edge of the fixed plate 8 of the adjacent baffle. The passage 6 will thereby be closed so that dust cannot escape therefrom. Dust will also not escape even when particulate material is fed only to a section of the device 2 since, as is illustrated in Figure 2, the independent action of each of restrictors 4 of the device means that only those restrictors 4 to which particulate material is fed will open. Furthermore, during rotation of the moveable plates 10, the fixed plates 8 and their flanges 16 will help to prevent any egress of dust from the passage 6.

The restrictors 4 may be arranged so that a very small gap exists between the lower edge of the moveable plates 10 of each restrictor 4 and the lower edge of the fixed plates 8 of the adjacent restrictors. Any fine coatings or individual particles can trickle through the gap between the restrictors. Therefore, all material fed onto the restrictors 4 should pass through into the passage 6.

Although shown in the Figures as comprising one row of restrictors 4, the dust containment device 2 could consist solely of one restrictor 4. Alternatively, it could consist of multiple parallel rows of restrictors 4, the longitudinal members 12 of the frame between each pair of rows acting to support the restrictors 4 in the pair of rows. The frame may additionally support a grill 24.

A dust extraction system 26 may be included, particularly if small gaps are provided between the restrictors. The gaps between the restrictors 4 will allow air to ingress into the hopper which will carry dust therewith. The dust extraction system 26 can be used to remove this dust. The volume of dust-laden gas which will have to be processed by the dust extraction system 26 will, however, be significantly reduced over that which would have to treated if the dust containment device 2 was not provided.

The restrictors 4 may be manufactured from any suitable material, examples of which are neoprene, marineply or steel. Rather than providing a separate sleeve 18, the moveable plate 10 could be rolled over at its upper end around the pivot pin 16 to form the necessary hinge.

However, by use of a separate sleeve 18, the moveable member 10 can be made of any material and is not restricted to a material suitable for a hinge device.

In the alternative embodiment illustrated in Figure 5, in which like parts are identified by like reference numerals, the moveable plate 10 is formed from a material suitable for forming part of a hinge, the material being flexible. The moveable plate 10 includes an integral extension 28 which is clamped, see 30, to thereby form the hinge between the extension 28 and the main body of the moveable member 10. The clamp 30 comprises a bolt 32 secured by a nut 34 through the integral extension 28 and a U-shaped channel 36. A washer 38 is positioned between the head of the bolt 32 and the integral extension 28 of the moveable member 10. The U-shaped channel 36 is, in turn, supported by an angled member 40 welded, see 42, to the associated fixed plate 8. The connection between the U-shaped channel 36 and the angled member 40 may be formed by welding or by bolting the two together. The extension 28 could be directly attached to the angled support member 40 but the illustrated arrangement is preferred as it allows the moveable plate 10 and channel 36 to be removed as a unit for repair or replacement. As many more bolts are required to fix the moveable plate 10 to a support than to fix channel 36 to angled member 40, the unit construction facilitates repair/replacement.

The advantage of this embodiment is that no separate pivot connection need be provided between the fixed plate 8 and the moveable plate 10. Suitable materials for the moveable plate 10 include rubber, plastic, fibres, textiles and metals or combinations thereof. Depending on the material, this embodiment may have the further advantage that the elasticity of the moveable member will cause it to return to the closed position or at least assist in doing so.

As is illustrated in Figure 5, the angle between the fixed plate 8 and flange 16 may alternatively be 90 or, in fact, even greater. Essentially, the angle needs to be such that the hinge below is sufficiently protected and material is guided onto the fixed plate of the adjacent baffle. Further, Figure 5 shows that the moveable plate 10 does not need to hang vertically in the closed position but may instead be at an angle to the vertical. Depending on the material of the moveable plate 10, it may in the latter case take up a bowed orientation and, if it has sufficient resilience, will act as a spring closure. The closed position of the moveable plates 10 will depend, amongst other things, on the spacing and angling of the fixed plates 8 and the location of the hinges.

The dust containment device 2 is simple in form and, therefore, relatively cheap to produce. Rotation of the moveable plates from the closed position to the open position is produced by the weight of particulate material thereon. The return swing is carried out under the action of gravity alone and/or the inherent elasticity of the moveable plate in the embodiment of Figure 5. Therefore, the device 2 requires no springs or other return mechanisms and will operate reliably. Reliable operation is further ensured by the fact that the hinges constituted by the pivot pins 16 and sleeves 18 are protected from particulate material by the flanges 16. Only one section of each restrictor 4 is moveable so that possible dust creation on opening and closing is reduced and only a relatively lightweight hinge mechanism is required.

Claims

1. A dust containment device for a container for particulate material comprising at least one opening and a restrictor for the opening comprising a baffle including a pair of baffle plates, a first of which is fixed in position and a second of which is moveable relative the first between a first position in which the baffle prevents egress of material from the container via the opening and a second position in which material can pass to the container, loading of the second plate with particulate material causing movement thereof from the first to the second position.

2. A dust containment device as claimed in Claim 1, wherein the first, fixed, plate of the baffle(s) is held at an angle to the axis of the opening such that it extends across at least part of the opening.

3. A dust containment device as claimed in either Claim 1 or Claim 2, wherein the second, moveable, plate of the baffle(s) is moveable between the first position, in which it lies generally parallel to the axis of the opening, and the second position in which it is generally parallel to the first, fixed, plate.

4. A dust containment device as claimed in any preceding Claim, wherein the second, moveable, plate of the baffle(s) is pivotally mounted at one edge thereof such that the plate may pivot between the first and second positions.

5. A dust containment device as claimed in any preceding Claim, wherein the second, moveable, plate of the baffle(s) is formed from a rigid material.

6. A dust containment device as claimed in any one of Claims 1 to 4, wherein the second, moveable, plate of the baffle(s) is formed from a flexible material.

7. dust containment device as claimed in either Claim 5 or Claim 6 as dependent on Claim 4, wherein the second, moveable, plate of the baffle(s) forms part of the pivot mount thereof.

8. A dust containment device as claimed in any preceding Claim, wherein the first, fixed, plate of the -baffle(s) includes a flange along one edge thereof such that the plate and flange together define a member of inverted V-shaped cross-section with one arm of the Vshaped member comprising the plate and the other arm, which is relatively much shorter, comprising the flange.

9. A dust containment device as claimed in Claim 8 when dependent on either Claim 4 or Claim 7, wherein the pivot mount of the second, moveable, plate is positioned between the associated first, fixed, plate and the flange thereof.

10. A dust containment device as claimed in any preceding Claim, including a plurality of restrictors arranged in at least one row of side-by-side baffles.

11. A dust containment device as claimed in Claim 10, wherein each restrictor includes a support frame for mounting the baffle thereof and wherein part of the support frame of the each restrictor is common with that of the restrictor or restrictors adjacent thereto.

12. A dust containment device as claimed in either Claim 10 or Claim 11, wherein the second, moveable, plate of each baffle in the or each row extends between one edge of the first, fixed, plate of the baffle and an opposite edge of the first, fixed, plate of an adjacent baffle.

13. A dust containment device as claimed in any preceding Claim, wherein the device is positioned in a passage leading to the access opening of the container for particulate material.

14. A dust containment system comprising a dust containment device as claimed in any preceding Claim, and a dust extraction system located between the container and the device.

15. A dust containment device substantially as hereinbefore described and illustrated in the accompanying drawings.