GB2266587A - Dust containment device - Google Patents

Abstract

A dust containment device is for a passage to a container or hopper for particulate material, and includes at least one restrictor along the passage. The or each restrictor comprises a support frame 8 and a baffle including a pair of baffle plates 10, each pivotally mounted along one edge to the support frame. The baffle plates are linked to a common counterbalance 16 such that in a closed state, the baffle has an inverted V-shaped cross-section and substantially prevents egress of material from the container via the openings. Loading of the baffle with particulate material in excess of a predetermined amount causes it to move to an open state in which the baffle plates pivot together whereby the baffle permits ingress of material to the container via the opening. The weights 22 on the counterbalance can be changed to modify the load at which the plates open. The edges of adjacent plates may not quite meet when closed to allow fine coatings or individual particles to trickle through. A passage may have a series of baffles some of which may be locked closed or open as required. There may also be steps to control the degree of closing of the baffles. <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 tracksinks, dumpsinks, 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, larger volumes of dust-laden air needs to be controlled and attempts to do so by dust extraction would be extremely, if not prohibitively, expensive.

Dust preventing 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 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 restrictor thereof. Firstly, for a restrictor to m6ve: 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. Secondly, the whole restrictor is swung clockwise or anticlockwise to move it from the closed to 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 restrictor could be such as to create turbulence in the hopper, thereby causing the dust problem to be worsened rather than improved.

Both of the above arrangements in addition suffer from the disadvantage that they cannot be readily adjusted to open at different loads so they will not readily accommodate different particulate materials or processes in which varying amounts of particulate materials are conveyed.

A dust containment device for passage to a container for particulate material in accordance with the invention comprises at least one opening and restrictor for the opening comprising a support frame and a baffle including a pair of baffle plates, each pivotally mounted along one edge to the support frame and linked to a common counterbalance such that in a closed state, the baffle has an inverted V-shaped cross-section and substantially prevents egress of material from the container via the opening, loading of the baffle with particulate material in excess of a predetermined amount causing it to move to an open state in which the baffle plates pivot together whereby the baffle permits egress of material to the container via the opening.

The advantage of this is that when the or each baffle moves from the closed state to the open state, the baffle plates rotate in opposite directions towards each other rather than both in the same direction in a controlled fashion, due to their linkage to the common counterbalance.

Furthermore, the common counterbalance will ensure that they rotate apart when the downward component of the weight of particulate material on the baffle plates falls below the gravitational force on the counterbalance. The baffle will operate in a controlled fashion and no means for ensuring uneven loading of the plates thereof is required.

There are many possible forms for the counterbalance.

However, whatever form it takes, it is much more likely to operate reliably than, for example, a pair of springs, as employed in the shutter restrictor described above.

Furthermore, it can readily be designed so that the weight thereof can be rapidly and easily varied so that the predetermined load amount can be varied This will render the containment device very flexible in use. A particularly suitable form for the counterbalance is a beam connected at each end thereof to the baffle plates by link arms pivoted to both the beam and one of the baffle plates.

Means may be provided for locking the baffle(s) in the open and/or closed state thereof. The locking means may comprise a stop member, suitably provided on the support frame, for preventing downwards and/or upwards movement of the counterbalance. The baffle or baffles can, therefore, be locked in their closed position to prevent ingress or egress of material from the passage with which the dust containment device is used. Alternatively, they can be locked in their open position if no dust containment or any partial dust containment is required in which position, due to their form, they only minimally reduce the area of the passage so that maximum material can be passed therethrough.

A restraint device may be provided which limits the downwards movement of the counterbalance and thereby sets the angle at which the baffle plates lie in the closed baffle state. This further increases the ability of the device to accommodate different types of material and/or different loadings.

The device can be used with a single restrictor, the opening then being the complete cross-section of the passage. However the modular form thereof means that a multi-restrictor device can readily be formed. The multiple restrictors are suitably arranged in a number of rows, part of the restraint frame of each restrictor being common with that of the restrictor or restrictors adjacent thereto. With a multi-restrictor device where only some of the baffles are in the open state, due to material being fed to only one region of the passage, or to the other restrictors being locked in the closed state, the closed baffles will prevent the egress of dust from the remainder of the passage area.

In a multi-restrictor device,; the baffles are preferably arranged so that, in their closed position, gaps exist therebetween. This can be achieved by suitable setting of the baffle plate length and/or by suitable setting of the restraint devices described above. The provision of gaps allows any fine coatings or individual particles to trickle between the baffles. Furthermore, if the container is provided with a dust extraction system, exhaust air can ingress into the container through the gap.

In a multi-restrictor device, some of the restrictors, particularly those at the sides, may include only a single baffle plate which carries a counterbalance thereon in a position such that the baffle plate normally lies at an angle to the vertical. A dust containment device could be formed solely from such restrictors, with the plates of all the restrictors lying at the same angle or with the plates on one half of the device lying at an opposite angle to those on the other half.

The invention will now be further described by way of example with reference to the accompanying drawings in which:- Figure 1 is a perspective view of a dust containment device in accordance with the invention having two restrictors; Figure 2 is a side view, partially cut away, of a restrictor of the device of Figure 1 with the baffle thereof in the closed position; Figure 3 is a section taken along line A-A of Figure 2; Figure 4 is a perspective view, partially in outline, of the restrictor of Figures 2 and 3 with the baffle in the fully open position; Figure 5 is a cross-section through a hopper containing a dust containment device in accordance with the invention, having multiple restrictors; and Figure 6 is a top plan view of the dust containment device of Figure 5.

Figure 1 shows a dust containment device 2 comprising two restrictors 4 positioned in an opening 6. Each restrictor 4 has a frame, comprising a hollow section 8, and a pair of baffle plates 10. Each baffle plate 10 is connected to the hollow section 8 by a pair of pivot mountings 12. Two link arms 14 are pivoted to each baffle plate 10, at 15a, and to a counterbalance 16, at 15b. The counterbalance 16 comprises an elongate beam with an aperture 18 at either end thereof. The beam 16 may have studs 20 extending from the base face thereof whereby one or more weights 22 can be bolted, see 24, thereto.

The restrictors 4 have end plates 26, each of which carries a pair of spaced guide plates 28. A restrictor plate 30 is removably attached across the lower ends of each pair of guide plates 28.

The restrictors 4 are mounted in the opening 6 by attachment of the end plates 26 to support bars, as will be described in greater detail later. The end plates 26 include cutouts 32 for receiving a lower support bar.

When in position in the opening 6, the counterbalance beam 16 of each restrictor 4 would move downwards under the action of gravity until the linkage constituted by the link arms 14 and baffle plates 10 was fully extended. The restrictor plates 30 limit this movement and halt the counterbalance beam 16 in the position shown in Figure 3 in which the baffle plates 10 lie at an angle to the vertical to give the baffle formed thereby an inverted V-shaped cross-section. The angle of the V-shaped cross-section will depend on the position of the restrictor plates which can be varied if a number of attachment points therefor are provided on the guide plate 28. Those guide plates 28 restrain the counterbalance beam 16 from sideways movement towards the baffle plates 10.

When the baffles formed by the baffle plates 10 have an inverted V-shaped cross-section, as shown in Figure 3, they are in a closed state and the resictors 4, of which they form a part, substantially prevent the passage of material through the opening 6. Thus, if the opening 6 were a passage leading to the hopper for particulate material, dust would be prevented from leaving the hopper and particulate material would be prevented from entering it. Discharge of particulate material from above the restrictors 4 will load the top surface of the baffle plate 10. When the downwards component of this loading exceeds the gravitational force on the counterbalance beam 16, that beam will rise and the baffle plates 10 will rotate towards each other due to the link arms 14 which will then adopt the position shown in Figure 4.The baffles will then be in an open state and the particulate material fed thereonto can pass through the opening 6. The baffles will close again when the feed of material ceases.

A locking plate 32 is provided for locking the baffles formed by the baffle plates 10 in their closed and their opened state. The locking plate 32 is attached to a locking bar 33 secured to one end pair of guide plates 28 by a mount 34 in which it is rotatable. The locking bar 33 includes an integral tongue 35. The locking plate 32 is shown in Figure 2 in the unlocked position thereof in which lies one side of the counterbalance beam 16 so that that beam 16 can move freely up and down. Rotation of the locking bar 33 through 900 brings the locking plate 32 into a position transverse to the counterbalance beam 16. If that beam 16 was initially in the lower position thereof, the locking plate 32 will extend across part of its top face and prevent it from moving upwards.If the counterbalance 16 is initially in its upper position, the locking plate 32 will pass through the hole 18 thereof and prevent it from downwards movement. Thus the locking plate 32 can lock the restrictor 4 with which it is provided with the baffle thereof in the open state and with the baffle thereof in the closed state. Means may be provided for preventing movement of the locking plate 32.

When in the locking and released positions thereof, this could be, as shown, a pin 36 which locates in holes 37a and 37b in the hollow frame beam 8 and tongue 35 of locking bar 33. The righthand pair of holes 37a holds the locking plate 32 in the released position whilst the lefthand pair of holes 37b holds the locking plate 32 in the locking position.

As shown in Figure 1, when the baffles of the restrictors 4 are in the closed state, a gap exists between the edges of the baffle plates 10 thereof. This can be achieved by making the baffle plates 10 of suitable length and/or by appropriately positioning the restrictor plates 30. Any fine coatings or individual particles can trickle through the gaps between the baffles. Therefore, all material fed on the restrictors all should pass through the passage 6.

Although shown in Figure 1 as comprising two restrictors 4, the dust containment device 2 could consist solely of one restrictor 4. The modular form of the restrictors 4, however, makes them particularly suitable for an arrangement in which the dust containment device 2 comprises a plurality of side-by-side rows of restrictors 4 mounted over a hopper 38 which comprises sides 40 and a bottom 42 which may discharge to a conveyor shoot or silo.

The hopper 38 includes supports 44 for a removable grill floor 46 and for a track.

In use, a vehicle is run over the track and is tipped or opened to let particulate material carried therein pass onto the grill floor 46 and into the dust containment device 2. It will be appreciated that unless material is fed over the whole top surface of the dust containment device 2, only the baffles of some of the restrictors 4 will move to the open state. The restrictors 4 with closed baffles will thus suppress the egress of dust from the hopper 38 during passage of particulate material thereinto.

If the restrictors 4 are provided with locking plates 32, then these can be used to ensure that some of the restrictors 4 will stay closed, no matter what the loading is, by locking the counterbalance beam 16 thereof in the downward position.

The provision of locking plates 32 for the restrictors 4 also means that the dust containment device 2 can be in effect de-activated when no dust containment is required. The locking plates 32 can be positioned to hold the counterbalance beams 16 of the restrictors 4 in their upper position so that all the baffles are in the open state. The form of the restrictors 4 when the baffles thereof are in the open state, i.e., the near parallel alignment of the baffles plates 10 thereof in this state means that there will be minimum reduction in the area of the upper open face of the hopper 38 so that maximum material can be fed thereto.

The dust containment device 2 comprises multiple transverse and longitudinal support bars 48, 50, see Figure 6. The restrictors 4 are attached to the support bars 48, 50 by their end plates 26. Thus each support bar 48 or 50 serves to mount at least two restrictors 4.

At the sides, the support plates 28 of the restrictors 4 are connected directly to the walls of the mouth of the hopper 38.

The hopper 38 preferably includes a dust extraction system 52. The gaps between the restrictors 4 allow exhaust air to ingress into the hopper 38 which takes dust therein into the extraction system 52. The volume of dust laden gas which will have to be processed by the dust extraction system 52 will be significantly reduced over that which it would be if the dust containment device 2 was not provided.

It will be appreciated that other arrangements of the restrictors in a multi-restrictor device 2 is possible. In particular, the device 2 could include a single row of endto-end restrictors and would be particularly suitable for use over a railway track.

Claims (10)

1. A dust containment device for a passage to a container for particulate material comprising at least one opening and a restrictor for the opening comprising a support frame and a baffle including a pair of baffle plates, each pivotally mounted along one edge to the support frame and linked to a common counterbalance such that in a closed state, the baffle has an inverted V-shaped cross-section and substantially prevents egress of material from the container via the opening, loading of the baffle with particulate material in excess of a predetermined amount causing it to move to an open state in which the baffle plates pivot together whereby the baffle permits ingress of material to the container via the opening.

2. A dust containment device as claimed in Claim 1, wherein means is provided for locking the baffle(s) in the open and/or the closed state thereof.

3. A dust containment device as claimed in Claim 2, wherein the locking means comprises a stop member for preventing downwards and/or upwards movement of the counterbalance.

4. A dust containment device as claimed in any preceding Claim, wherein a restraint device is provided which limits downwards movement of the counterbalance of the or each baffle and thereby sets the angle at which the baffle plates thereof lie in the closed baffle state.

5. A dust containment device as claimed in any preceding Claim, wherein the counterbalance of the or each baffle comprises a beam linked at each end thereof to the baffle plates of the baffle.

6. A dust containment device as claimed in any preceding Claim, wherein the counterbalance(s) has a variable weight whereby the predetermined load amount can be varied.

7. A dust containment device as claimed in any preceding Claim, wherein a plurality of restrictors is provided arranged side by side in at least one row, part of the restraint frame of each restrictor being common with that of the restrictor or restrictors to the side thereof and/or in adjacent rows thereto.

8. A dust containment device as claimed in any preceding Claim, wherein a plurality of restrictors is provided arranged side by side in at least one row, and wherein the baffles are arranged so that, in the closed position thereof, a gap exists between the lower edges of the baffle plates of adjacent restrictors.

9. A hopper or the like for containing particulate material having a passage leading thereto and a dust containment device for the passage as claimed in any preceding Claim, wherein the passage and/or hopper is provided with a dust extraction system.

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