GB2199569A

GB2199569A - Preventing dust release when loading hoppers

Info

Publication number: GB2199569A
Application number: GB08700236A
Authority: GB
Inventors: Peter D Merrion
Original assignee: E & F Services Ltd
Current assignee: E & F Services Ltd
Priority date: 1987-01-07
Filing date: 1987-01-07
Publication date: 1988-07-13
Anticipated expiration: 2007-01-07
Also published as: GB8907536D0; GB2199569B; GB8700236D0; GB2214906A; GB2214906B

Abstract

A hopper 2 having an inlet spout 4, for receiving a materials delivery device, which extends into a storage chamber 3 of the hopper 2, has a plurality of ports 25 communicating with the chamber 3 and through them air can be extracted, by fans 22 through filter units 23, from a region of the chamber 3 around the lower end of the inlet spout 4. Dust collected by the filter units 23 is gravity fed through ducts 27 back into the chamber 3. A canopy 6 is provided under which a truck can be disposed, with a discharge mechanism 5 operative to discharge material from the chamber 3 into the truck. Dust-laden air can be extracted from within the canopy 6 through extraction ports 28 in the roof of the canopy 6. <IMAGE>

Description

Title:Materials Handling Device The invention relates to materials handling devices generally and is particularly, but not exclusively, concerned with a mobile dockside materials handling device.

Particulate material cargoes, for example cereals such as rice or wheat, are often unloaded from the holds of ships using a mechanical bucket-grab of a crane. A load material picked up by the grab is subsequently deposited into an intermediate store or silo from which trucks or wagons can be filled.

A proportion of any load will consist of very fine particles or dust which can become airborne when released by the grab or discharged from the intermediate store. Such airborne dust, which may amount to 10% of the total load, is often seen to be an environmental pollutant and it may present a serious explosives hazard when in an enclosed space such as an entrance region of the store.

Various designs of intermediate store are available which use dust extraction systems. These designs are far from ideal and frequently incorporate unwieldy structures and inefficient extraction systems which fail to capture a material proportion of the dust created.

It is an object of the invention to obviate or mitigate various disadvantages of the available designs and in particular to provide an intermediate store with an efficient dust extraction system.

According to a first aspect of the invention a materials handling device comprises a hopper having an inlet spout for receiving a materials delivery device and which extends into a storage chamber of the hopper, and a port which communicates with the storage chamber and through which air can be extracted from a region of the storage chamber around at least a part of an external periphery of the inlet spout.

According to a second aspect of the invention a materials handling device comprises a hopper having a storage chamber, and a filter unit through which air can be extracted from the storage chamber and from which any dust collected is gravity fed back into the storage chamber, at a location removed from the filter unit for free discharge into a truck.

According to a third aspect of the invention a materials handling device comprises a canopy under which a truck can be disposed, having a first port through which material can be discharged and a second port through which air can be extracted.

Preferably the canopy is in the form of a hood consisting of a roof portion with ends and side curtains.

A series of ducts may be provided around the four top sides of the canopy but within the end and side curtains which can direct, singularly or collectively, fan exhaust air downwards to form a complete or partial clear air curtain around the truck making an effective seal for excessively dusty cargoes so helping with extraction by other parts.

The invention will now be further described by way of example with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side view of a materials handling device in accordance with a preferred embodiment of the invention; Figure 2 is a diagrammatic end view of the preferred embodiment; Figure 3 is a diagrammatic plan view of the preferred embodiment; and Figure 4 is a diagram of an exhaust duct of the preferred embodiment.

A mobile dockside materials handling device, illustrated in Figures 1 to 3, consists of a steel framed rolling chassis 1 supporting a materials hopper 2. The hopper 2 has a storage chamber 3, loadable at its upper end through an inlet spout 4 and unloadable at its lower end through a discharge mechanism 5. The chassis 1 can accommodate an open topped truck (not shown) under a hood 6 into which two discharge spouts 7 of the mechanism 5 open.

The chamber 3 of the hopper 2 is formed from a lower end portion 8 of an open-ended box member 9 and a downwardly tapering flat-sided body section 10. An upper end of the body section 10 is connected to the periphery of a lower end of the member 9 by a closure plate 11 with a through opening which continues the internal cross-section of the box member 9. A lower end of the body section 10 terminates at the periphery 13 of the discharge mechanism 5.

Inlet spout 4 is formed by an upper end portion 14 of the box member 9, an outwardly tapering mouth section 15 attached to an upper end of the member 9, and a downwardly tapering funnel section 16 fixed to the internal wall 12 of the member 9 and extending into the storage chamber 3. A mesh grid 17 is disposed across a lower opening of the funnel 16 to prevent the passage of large foreign objects, for example sacks, into the chamber 3.

The discharge mechanism 5 is typically a rotary or a vibratory discharge mechanism having two large bore discharge spouts 7 through which foreign bodies, such as small metal objects, can pass through without hindrance or causing damage. Each of the spouts 7 extends through a rectangular roof plate 18 of the hood 6, and is thus able to discharge materials into a truck positioned below the roof plate 18.

A side curtain 19 surrounds the periphery of the roof plate 18 to complete the hood 6 but is sealed at each side of the cab so that the drivers vision is not obsured by curtains.

This curtain 19 may be provided by a series of movable rigid or flexible members. Conveniently the curtain 19 is flexible and transparent and consists of a multiplicity of elongate plastics strips (not shown) pivotally hung from the periphery of the roof 18. Thus, a truck can be driven past the curtain 19 causing the plastics strips to swing out of its way and to subsequently return to a rest position once the truck has passed.

To provide the handling device with the mobility required for dockside operation, the chassis 1 is mounted on four wheels 20, two of which are steerable and motor driven.

Suitably, each of the steerable wheels is driven by a corresponding hydraulic motor (not shown) controlled by an operator positioned in a cab 21 of the mobile handling device.

A dust extraction unit of the handling device consists of four extraction fans 22, the suspensions of which are mounted on the roof plate 18. Three of the fans 22 each, via ducting not shown, extract air from a clean side of a pair of filter units 23. Whilst the fourth fan 22 similarly extracts air from a filter unit 24.

The filter units 23 are each mounted in pairs on the closure plate 11 adjacent a corresponding one of three sides of the box member 9. An associated first inlet duct 25 extends between each filter unit 23 and a region 26 of the chamber 3 surrounding an external periphery of the funnel 16. A respective discharge outlet for filter cake 27 of each unit 23 extends through the base of the unit and the closure plate 11 and is thus open to the chamber 3.

An inlet duct (not shown) of the filter unit 24 is connected to a plurality of extraction ports 28 which extend through the roof plate 18 of the hood 6. A screw convenyor 29 is provided between the discharge outlet for filter cake unit 24 and a discharge spout 30 exending through the plate 18.

Each fan 22 is mounted on the plate 18 adjacent one of the sides of the hood 6. An associated exhaust duct 31 of each fan 22 contains a flap valve 32, see Figure 4. The valve 32 can be operated to enable exhaust directly to atmosphere from the duct 31 or to direct the exhaust through a corresponding exhaust duct 33. Each duct 33 extends along a substantial length of the upper periphery of the associated side of the hood 6, and has an elongate lower slot 34 through which air can be exhausted to form a downdraught air curtain internally of the hood 6, and curtains 19.

The mobility of the handling device enables it to be positioned alongside a ship when it has'docked along a quayside. In operation a mechanical bucket-grab of a crane, or other suitable materials handling device, delivers a load of material, for example of rice or wheat, into the mouth 15 of the inlet spout 4.

The mechanical grab can be lowered into the spout 4 until it is enclosed or until its movement is prevented by the grid 17. With the fans 22 associated with the filter units 23 running, the grab releases its load which falls toward the chamber 3 and results in a substantial volume of airborne dust.

Air sucked into the filter units 23 through the inlet ducts 25 and 26 is drawn through the inlet spout 4 and is funnelled by the lower section 16. Hence, a downdraught is created around the enclosed grab in which the airborne dust is entrained. Thus, the dust created by the release of material into the hopper 2 is extracted from the chamber 3 and collects in the filter units 23. The dust cake collected on the filter units 23 is able to fall under gravity through the outlet 27 into the chamber 3 using conventional reverse-flow jet cleaning techniques.

To discharge material from the hopper 2 a truck or wagon is positioned under the hood 6 and a loading operation is observed and controlled by the operator seated in the cab 21. With the fan 22 extracting air from the filter unit 24 an updraft is created between the sides of the truck and the adjacent curtain 19 of the hood 6. Material is discharged into the truck through the spouts 7 by the operation of the discharge mechanism 5, this creates a considerable amount of airborne dust. This dust will in the main by entrained by the updraught and carried through the extraction ports 28 and subsequently collected in the filter unit 24. Dust collected in the filter unit 24 can fall into the input end of the screw-convenyor 29 which discharges the dust through the spout 30 into the truck.

It will be appreciated therefore, that the dust extraction system of the illustrated device not only collects but also recycles the dust. However, it is recognised that a small amount of dust may escape from beneath the hood 6 and cause a build up of particulate material on the outside of the curtain 19. Alternatively, a cloud of dust is more likely to form which will obscure the view of the operator in cab 21 To prevent the formation of a dust cloud around the outside periphery of the hood 6, the flap valves 32 are operated to direct the exhaust from the fans 22 through the elongate slots 34. Thus, a curtain of air is formed which forms a seal as directed by the operator around the truck and under the hood.

The independent operation of the flap valves 32 enables the air curtain around each of the four sides of the hood 6 to be controlled individually. Thus, when a loaded truck or wagon is driven from under the hood 6, the appropriate valve or valves 32 can be operated to direct the exhaust air away from the corresponding ducts 33 and so away from the truck or wagon.

Claims

CLAIMS:

1. A materials handling device comprising a hopper having an inlet spout for receiving a materials delivery device and which extends into a storage chamber of the hopper, and a port which communicates with the storage chamber and through which air can be extracted from a region of the storage chamber around at least a part of an external periphery of the inlet spout.

2. A materials handling device according to claim 1, wherein said port is one of a plurality of ports disposed at a side wall of the chamber and distributed around a lower end of the inlet spout within the chamber.

3. A materials handling device according to claim 2, wherein a plurality of external filter units are mounted alongside the chamber with inlet ducts which respectively communicate with said ports, further inlet ducts of the filter units extending from the storage chamber at a lower level whereby dust collected in the filter units falls under gravity back into the chamber through said further inlet ducts.

4. A materials handling device according to claim 3, wherein the inlet spout and the storage chamber are of rectangular form in plan view, and said filter units are mounted in three pairs thereof respectively disposed at three sides of the storage chamber.

5. A materials handling device according to claim 3 or claim 4, wherein a separate extractor fan has an inlet connected to the clean air side of each filter unit.

6. A materials handling device according to claim 4 and claim 5, wherein said extractor fan is one of three such fans the inlets of which are respectively connected to said three pairs of filter units.

7. A materials handling device according to claim 5 or claim 6, wherein the or each extractor fan has an exhaust duct with a valve such that the fan can exhaust directly to atmosphere or alongside a hood of the device under which a truck can be disposed to receive material discharged from the storage chamber, whereby to provide a downdraft air curtain eternally of the hood.

8. A materials handling device comprising a hopper having a storage chamber, and a filter unit through which air can be extracted from the storage chamber and from WhiCil any dust coilected by the filter unit from the extracted air is gravity fed back into the storage chamber at a location removed from the filter unit for free discharge into a brick.

9. A materials handling device comprising a canopy under which a truck can be disposed, the device having a first port through which material can be discharged into a truck disposed beneath the canopy and a second port through which dust-laden air can be extracted from within the canopy.

10. A materials handling device according to claim 9, wherein the canopy is disposed below a storage chamber for the material and from which the material can be discharged through said first port.

11. A materials handling device according to claim 9 or claim 10, wherein the canopy is in the form of a hood consisting of a roof portion and a side curtain, and the device comprises a duct from which air can be blown past at least a part of an external surface of the hood to provide a downdraft air curtain.

12. A materials handling device according to any one of claims 9 to 11, wherein the canopy is in the form of a hood consisting of a roof portion and a side curtain, and said second port is disposed in said roof portion.

13. A materials handling device according to claim 12, wherein said second port is one of a plurality of such ports in the roof portion.

14. A materials handling device according to claim 12 or claim 13, wherein the device comprises an extractor fan with an inlet connected to the clean air side of a related filter unit connected to said second port or ports, means being provided to deliver dust collected by said related filter unit into the truck receiving the material being discharged.

15. A materials handling device according to claim 4 and claim 14, wherein said related filter unit is mounted at the fourth side of said storage chamber.

16. A materials handling device according to claim 14 or claim 15, wherein said means to deliver collected dust comprises a screw conveyor with a delivery spout extending through said roof portion of the canopy.

17. A materials handling device constructed and arranged substantially as hereinhefore particularly described with reference to the accompanying drawings.