GB2320004A - Air conveyor - Google Patents

Abstract

An air conveyor comprises a generally flat deck divided into a plurality of zones (5A-5D). The deck in each zone is provided with parallel rows of slots for the passage of air from below. The slots are arranged to generate a generally linear air flow across each zone of the deck. The space beneath the deck is divided into a plurality of separate plenum chambers and air is controlledly supplied to each of the plenum chambers.

Description

AIR CONVEYOR In many industrial and other environments there is a need to collect and convey away particulate or other waste material being generated in an industrial process.

The conveyors may be mechanical, such as moving belts, or, particularly where the available height is limited, air conveyors may be used. An air conveyor may consist of a slotted deck with a supply of pressurised air being introduced below the deck to create an air current passing upwardly through and along the deck. The air current picks up the material and carries it along to an outlet for further treatment.

A problem with such systems arises when control of the direction, speed and height of the material being moved is required. A number of methods have been proposed in which material is moved in one or more directions with guides or and other mechanisms used to direct the material. Such systems have never been fully satisfactory since they cannot cperate under optimum conditions due to reduced control here larger areas are to be covered by the device, or where space limitations reduce the practicality or etfectiveness of guides or other methods.

It is an object of the invention to provide an improved air convey system which can receive a wide variety of material over a small or large area to move or transport the material to another location or to gather from the area to a single point for easier handling or further processing.

The air conveyor of the present invention has no moving parts and does not therefore suffer from the problems associated with belt and other conveyors which have a tendency to jam and block because of material entering the operating system or building up in an undesirable way. This invention is also inherently safe, allowing personnel to walk on, or make contact with the deck while the conveyor is in operation.

In air conveyors of this kind it is important to generate a carefully controlled layer of air across the surface of the deck to convey the material in the most efficient way. This control is essential to avoid material becoming fully airborne and escaping the confines of the conveyor. Similarly, if the material contains dust, it is important the overall air flow is laminar with a low height above the deck to avoid unacceptable dust release from the conveyor. When particles or other solids material falls onto or makes contact with the deck it is elevated on the largely laminar flow of fluid and is moved in a desired direction.

According a the present invention there is provided an air conveyor comprising: a generally flat or contoured deck providing a surface over which material is to be conveyed; outlets formed in the deck for the through passage of air from beneath the deck to generate a flow of air across the deck; means for controlledly supplying air to the space beneath the deck such that flow through the outlets in at least two different control areas of the deck can be independently controlled.

An embodiment of the present invention is described below, with reference to the accompanying drawings, in which: Figure 1 is a highly diagrammatic vertical section through a portion of an air conveyor; Figure 2 is a diagrammatic plan view of an air conveyor on a smaller scale; and Figure 3 is a view, similar to that of Figure 1, of an alternative embodiment.

As can be seen from Figures 1 and 2, the conveyor comprises a generally flat and horizontal deck.

The deck can be mounted above the floor or ground level 2 or set within the floor such that the deck surface can be level with or below the surrounding surface or floor area.

Floor 2 may be formed as part of the machine or by the existence of a surface external to the machine. The deck is provided with perforations or outlets in the form of elongated slots or other profiled discharge vents 4 depressed within or raised above the surface of the deck 1 and arranged in parallel rows. As seen in Figure 2, the deck can be divided into a plurality of zones 5A-5F; the rows of slots in each zone of the deck being parallel to one another so as to generate a generally linear air flow across each zone in a direction perpendicular to the slots.

The deck is also divided into separate control areas A, B, C which may correspond wholly or in part with the zones of the deck or may be quite distinct from the zones of the deck, as shown. The space beneath the deck is divided into separate plenum chambers 7, 8, 9 which correspond to the control areas of the deck. The chambers 7, 8, 9 are formed at the bottom by a horizontal wall or floor 2, at the sides by vertical walls 13 extending downwardly from the deck and at the top by the deck. Air is independently and controlledly supplied to each of the chambers through inlets shown diagrammatically at 10, 11 and 12 and controlled by valves 14. One or more blowers, fans or other means (not shown) provide pressurised air into the chambers 7, 8, 9. Thus the air supply to each of the chambers 7, 8, 9 and the flow through the slots 4 in each of the control areas A, B and C are independently controlled.

As can be seen from Figure 2, the slots 4 in the deck 1 are oriented to direct the air into the desired direction. Air emerging through the slots within each zone of the deck creates a generally laminar flow of air across that zone of the deck indicated by the arrows in Figure 2.

The volume and velocity of air flowing out of the each chamber 7, 8, 9 may be further controlled by varying the number, size and configuration of the slots 4.

In a modified embodiment, shown in Figure 3, a horizontal wall 15 is formed between the deck 3 and the floor 2 such that one or more second plenum chambers 16 are formed beneath the first plenum chambers 7, 8, 9. Air is supplied to the second plenum chambers and then is fed to the first plenum chambers through control valves 17.

In a further embodiment (not shown) a plenum chamber is located beneath each zone of the deck for supplying air to that zone of the deck.

The air flow and pressure must be higher in areas where particles are making initial contact with the deck as this must be sufficient to elevate the particles and solids above the surface and to accelerate them to the desired speed. In areas where the particles and solids have already achieved the desired velocity, lower pressure and volume flow is required to maintain this state as any further input of energy may cause a loss of control of the particles possibly resulting in particles being released from the confines of the machine.

Because of the very low friction associated with this form of material transfer, changes of direction may require the material to be decelerated prior to the change of direction and then re-accelerated in the new directions; for example when particles are moved from control area B to control area C.

The deck is preferably made of thin gauge steel of sufficient strength to be used as a floor by operators.

The slots are precision punched into the deck and are about 0.5-1.0 mm in height and about 40-50 mm long.

It will be appreciated that other compressible fluids, such as for example Nitrogen, may be used instead of air where appropriate. All references herein to "air" should be interpreted in this light.

Claims (7)

1. An air conveyor comprising: a generally flat or contoured deck providing a surface over which material is to be conveyed; outlets formed in the deck for the through passage of air from beneath the deck to generate a flow of air across the deck; means for controlledly supplying air to the space beneath the deck such that flow through the outlets in at least two different control areas of the deck can be independently controlled.

2. An air conveyor as claimed in Claim 1, wherein the openings in the deck comprise rows of elongate slots and the deck is divided into a plurality of separate zones; the rows of slots in each zone of the deck being parallel to one another so as to generate a generally linear air flow across each zone of the deck in a direction perpendicular to the slots.

3. An air conveyor as claimed in Claim 2, wherein the slots produce an air flow in at least one zone which is inclined to the air flow in at least one other zone.

t. An air conveyor as claimed in any preceding claim, wherein the space beneath the deck is divided into a plurality of separate plenum chambers which correspond to the control areas or the deck and wherein the means for controlledly supplying air comprises means for controlledly supplying air independently to each of the separate plenum chambers.

5. An air conveyor as claimed in Claim 4, wherein the plenum chambers are defined at the bottom by a horizontal wall or floor spaced below the deck, at the sides by vertical walls extending downwardly from the deck to the horizontal wall or floor, and at the top by the deck.

6. An air conveyor as claimed in Claim 1, wherein the space beneath the deck is divided into a plurality of separate first plenum chambers which correspond to the control areas of the deck and wherein one or more second plenum chambers are provided, each supplying air to one or more of the first plenum chambers through one or more control valves.

7. An air conveyor substantially as described herein with reference to the accompanying drawings.