WO2002034654A2

WO2002034654A2 - Material discharge apparatus

Info

Publication number: WO2002034654A2
Application number: PCT/IB2001/002006
Authority: WO
Inventors: Graeme John Taylor
Original assignee: Albertson, Derek, William
Priority date: 2000-10-25
Filing date: 2001-10-25
Publication date: 2002-05-02
Also published as: AU2002210821A1; WO2002034654A3

Abstract

Material discharge apparatus is provided having a substantially upright chute which is extendable in its length and through which material operatively flows under gravity from an inlet to a discharge end. Control means are provided to control the discharge of the material from the chute, by controlling the length of the chute and the height of the discharge end relative to the surface onto which the material is discharged, to maintain the level of material in the chute within a predetermined range.

Description

MATERIAL DISCHARGE APPARATUS

FIELD OF THE INVENTION

This invention relates to apparatus for discharging material, particularly flowable particulate material.

BACKGROUND TO THE INVENTION

Loading of ships, other vehicles and stockpiles with particulate material generally requires apparatus which continually discharges the material. One such apparatus allows the material to fall directly onto the vehicle while others make use of an upright chute which is fed with material from its upper end and discharges the material at its lower end. While these devices are fairly effective they do suffer a number of disadvantages, one of the most important of which is that they tend to promote the production of dust. This creates an environmental hazard especially as dust is known to be explosive under certain conditions. Also, as the material normally falls some distance it is often subject to degradation thereby creating an excess of fine material. Such degraded material is often less valuable and may cause processing problems when used. The chutes themselves also experience relatively high wear due to the abrasive effect and impact loading of the material falling therethrough.

OBJECT OF THE INVENTION

It is an object of this invention to provide material discharge apparatus which will at least partially alleviate some of the abovementioned problems. SUMMARY OF THE INVENTION

In accordance with this invention there is provided material discharge apparatus comprising a substantially upright chute through which material operatively flows under gravity from an inlet to a discharge end and control means to operatively control the discharge of material from the chute to maintain the level of material in the chute within a predetermined range.

Further features of the invention provide for there to be level measurement means to measure the level of material within the chute; for the chute to be extendable in its length; for the control means to operatively control the length of the chute; for the control means to include at least one winch operated cable secured to or adjacent the discharge end of the chute; for the control means to further include a height sensor to measure the height of the discharge end relative to the surface onto which material is discharged; and for the surface to include the surface of material discharged from the chute.

Still further features of the invention provide for level measurement means and height measurement means to operate using ultrasonics, tilt switches, radar or laser; for the control means to include a processor to control operation of the winch based on the measured level of material within the chute and the height of the discharge end above a surface; for the discharge end to be crenellated; and for the discharge end to discharge material in a direction substantially parallel to the axis of the chute, alternatively in a direction transverse to the axis of the chute.

Still further features of the invention provide for a spreader to extend from the discharge end of the chute to operatively direct material in a direction transverse to the axis of the chute; and for the spreader to include a tube with a screw conveyor extending along the length thereof or a belt conveyor.

The invention also provides a method of discharging material from an upright chute which includes filling the chute with material to a predetermined level and controlling the rate of discharge of material from a discharge end of the chute to maintain the level of material in the chute within a predetermined range.

Further features of the invention provide for the material to substantially fill the chute; for the rate of discharge to be controlled by maintaining the discharge end of the chute in proximity to a surface therebelow; for the discharge end to be maintained in proximity to the surface by adjusting the length of the chute; and for the discharge end to be placed in proximity to the surface prior to filling the chute with material, alternately for the rate of discharge to be controlled by a gate at or near the discharge end of the chute ; for the discharge end to be closed prior to filling the chute with material; and for the chute to be filled with material to a predetermined level with the chute in a contracted condition, for the chute to be extended to position the discharge end in proximity with the loading surface, and for the lowermost end to then be opened to allow material to flow therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described, by way of example only, with reference to the drawings in which: Figure 1 is a part sectional side elevation of a material discharge apparatus; Figure 2 is a side elevation of part of the discharge end of the apparatus in Figure 1 ; Figure 3 is a side elevation of part of the discharge end of a second embodiment of material discharge apparatus;

Figure 4 is a side elevation of part of the discharge end of a third embodiment of material discharge apparatus; Figure 5 is a part sectional side elevation of part of the discharge end of a fourth embodiment of material discharge apparatus; and Figure 6 is a part sectional side elevation of part of the discharge end of a fifth embodiment of material discharge apparatus. DETAILED DESCRIPTION OF THE DRAWINGS

Material discharge apparatus (1) is shown in Figure 1 and includes an upright chute (2) which depends from its uppermost end (3) from a boom assembly (4). A conveyor belt (5) supported on the boom assembly (4) discharges over the uppermost end (3) of the chute (2) into a shrouded inlet (7).

The chute (2) is formed from a plurality of telescoping tubes (8), the lowermost (8a) of which has the largest diameter and provides the discharge end (9) of the chute (2). Three cables (10) (two shown) are each secured at one end to the lowermost tube (8a) equally spaced about its circumference, and to a winch (11 ) at the opposite end.

A radar operated level sensor (12) is secured within the chute (2) above the inlet (7) and a radar operated height sensor (14) is secured to the outer surface of the chute (2) adjacent the discharge end (9).

In use, the chute (2) is moved into position in a contracted condition using the boom (4). In this condition, the tubes (8) are fully telescoped into each other by operating the winch (11) to withdraw the cables (10). Once in position the chute (2) is extended by operating the winch (11) to release the cables (10) until the discharge end (9) is in close proximity to the surface (20) onto which material is to be discharged. This is conveniently achieved using the height sensor (14) which continuously monitors the height of the discharge end (9) above the surface (20) and stops operation of the winch (11 ) when the height is less than about 0.1 m.

Once the chute (2) is extended to the correct height above the surface (20) the conveyor (5) is operated to discharge material (25) into the inlet (7) of the chute (2). As the discharge end (9) of the chute (2) is in close proximity to the surface (20) the material (25) becomes trapped within the chute (2) and fills the chute (2). The level sensor (12) monitors the height of the material (25) within the chute (2). When the level reaches a predetermined minimum near the inlet (7) the sensor (12) causes the winch (11) to operate and withdraw the cables (10). This causes the discharge end (9) to lift above the surface (20) which results in material (25) discharging therefrom.

By controlling the height of the discharge end (9) above the surface (20) the rate of discharge of material (25) therefrom can be controlled. Once a pile (26) of material has been formed, the rate of discharge will naturally be controlled by controlling the height of the discharge end (9) above the surface of the pile (26). If a higher rate of discharge is required the discharge end (9) will be lifted faster and if a lower rate of discharge is required the discharge end (9) will be lifted more slowly.

The rate of discharge of material (25) is controlled to approximate the rate of feed into the inlet (7) to thus maintain the level of material (25) in the chute (2) within a predetermined range close to the inlet (7). A processor (not shown) connected to the level sensor (12) is programmed to control the winch (11 ) and hence the rate of discharge based on measurements from the level sensor (12).

As shown in Figure 2, the discharge end (9) of the chute (8) is crenellated to form a series of radiused teeth (30). It has been found that this configuration greatly assists in controlling the rate of discharge of material (25) form the chute (8) as there tends to be a more regular flow of material and less slumping of the pile (26) when the discharge end (9) is moved upwardly than with an end without crenellations. Depending on the material being discharged, however, the crenellations may take other forms. As shown in Figure 3, the crenellations could be formed by a series of spaced notches (35) in the discharge end (9) or even by apertures (37) in the chute adjacent the discharge end (9) as shown in Figure 4.

By maintaining the level of material in the chute a gentle and controlled mass flow is achieved. This minimises dust generation and material degradation and also reduces impact loading and abrasion between the material and the components of the chute, and hence wear, on the chute. This also allows the chute to be operated efficiently at any throughput capacity ranging from 0 to 100 percent whereas other degradation and dust reduction chutes can be inefficient at capacities below 100 percent.

It will be appreciated, however, that many other embodiments of material discharge apparatus exist which fall within the scope of the invention especially as regards the configuration and control thereof. As shown in Figure 5, the discharge end (9) of the chute (8) could have a pair of gates (40) operated by hydraulic rams (41 ) secured thereto to control the flow of material through the chute (8). Thus, instead of controlling the flow of material by adjusting the height of the discharge end (9) above the surface of the pile (26), the gates (40) can be opened or closed to adjust flow rate. A further advantage of the gates (40) is that the chute can be filled with material with the gates (40) closed and preferably with the chute (8) in a contracted condition. As the chute (8) fills with material it can be extended until adjacent to the loading surface (20) and the gates (40) then opened to allow the material to discharge. This method of filling the chute (8) ensures that the material experiences a minimal drop, as opposed to when the chute is first lowered and then filled, and hence there is a further reduction in material degradation and dust formation. Clearly any suitable gate can be used to control flow of material through the discharge end of the chute.

It will further be appreciated that the discharge end of the chute may be configured to allow discharge in a substantially radial direction. For example, as shown in Figure 6, a transversely extending spreader (60) could be attached to the end of the chute. In this embodiment the spreader (60) includes a radially extending tube (61 ) with a screw conveyor (62) secured therein. The screw conveyor (62) will not only feed material through the tube (61) but can be used to control the rate of discharge from the chute (8). By rotating either the spreader (61 ) or the chute (8) material can be distributed more widely to make more effective use of the volume available. The spreader need not, however, make use of a screw conveyor and could include a belt conveyor or other suitable feed means. The spreader may even be formed by inclining the discharge end of the chute to the axis of the chute. Any convenient means can be used to measure the level of the material within the chute including ultrasonics, laser and tilt switches and the means used will be selected to suit the particular application. For example, where dust is produced ultrasonics will preferably be avoided. Also, any means can be used to control the extension of the chute. However, the chute need not be extendable and could be positioned between two fixed points, such as a pair of vertically spaced conveyors.

Still further, the chute need not be positioned below a belt conveyor and any suitable feed means could be used. For example, the chute could be positioned below a silo or bunker.

Claims

1. Material discharge apparatus comprising a substantially upright chute through which material operatively flows under gravity from an inlet to a discharge end and control means to operatively control the discharge of material from the chute to maintain the level of material in the chute within a predetermined range.

2. Material discharge apparatus as claimed in claim 1 which includes level measurement means to measure the level of material within the chute.

3. Material discharge apparatus as claimed in claim 2 in which the level measurement means operates using any one of ultrasonics, radar, laser and a tilt switch.

4. Material discharge apparatus as claimed in any one of the preceding claims in which the chute is extendable in its length.

5. Material discharge apparatus as claimed in claim 4 in which the control means operatively controls the length of the chute.

6. Material discharge apparatus as claimed in claim 5 in which the control means includes at least one winch operated cable secured to or adjacent the discharge end of the chute.

7. Material discharge apparatus as claimed in any one of claims 4 to 6 in which the control means further includes a height sensor to measure the height of the discharge end relative to a surface onto which material is discharged.

8. Material discharge apparatus as claimed in claim 7 in which the surface includes the surface of material discharged from the chute.

9. Material discharge apparatus as claimed in claim 7 or claim 8 in which the height sensor operates using any one of ultrasonics, radar, laser and a tilt switch.

10. Material discharge apparatus as claimed in any one of claims 4 to 9 in which the control means includes a processor to control operation of the winch based on the measured level of material within the chute and the height of the discharge end above a surface onto which material is discharged.

11. Material discharge apparatus as claimed in any one of the preceding claims in which the discharge end of the chute discharges material in a direction substantially parallel to the axis of the chute.

12. Material discharge apparatus as claimed in any one of the preceding claims in which the discharge end of the chute is crenellated.

13. Material discharge apparatus as claimed in any one of claims 1 to 10 in which the chute discharges material in a direction transverse to the axis of the chute.

14. Material discharge apparatus as claimed in claim 13 in which a spreader extends from the discharge end of the chute to operatively direct material in a direction transverse to the axis of the chute.

15. Material discharge apparatus as claimed in claim 14 in which the spreader includes a tube with a screw conveyor extending along the length thereof.

16. Material discharge apparatus as claimed in claim 14 in which the spreader includes a belt conveyor.

17. A method of discharging material from an upright chute which includes filling the chute with material to a predetermined level and controlling the rate of discharge of material from a discharge end of the chute to maintain the level of material in the chute within a predetermined range.

18. A method of discharging material as claimed in claim 17 in which the material substantially fills the chute.

19. A method of discharging material as claimed in claim 17 or claim 18 in which the rate of discharge is controlled by maintaining the discharge end of the chute in proximity to a surface therebelow.

20. A method of discharging material as claimed in claim 19 in which the discharge end is maintained in proximity to the surface by adjusting the length of the chute.

21.A method of discharging material as claimed in claim 19 or claim 20 in which the discharge end is placed in proximity to the surface prior to filling the chute with material.

22. A method of discharging material as claimed in claim 17 or claim 18 in

25. Material discharge apparatus substantially as herein described and as illustrated with reference to Figures 1 and 2 or any one of Figure 3 to Figure 6.

26. A method of discharging material substantially as herein described and as illustrated with reference to Figures 1 and 2 or any one of Figure 3 to Figure 6.