GB2467526A

GB2467526A - Flexible rotary mesh filter

Info

Publication number: GB2467526A
Application number: GB0901613A
Authority: GB
Inventors: Andrew Baughan
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-02-02
Filing date: 2009-02-02
Publication date: 2010-08-04
Also published as: GB0901613D0; WO2010086670A1

Abstract

Disclosed is an elastic or flexible rotary mesh filter 3. A number of such filters 3 may be attached to a rotatable frame 2. Upon rotation of the frame 2, a semi rigid member or flapper 7 may press against the filters 3 causing them to flex. This may cause apertures in the filters 3 to enlarge, urging debris stuck in the filters 3 to fall back into the centre of the rotatable frame 3. The flexibility of the filter panels 3 may thus permit self cleaning function in a rotary separator. The weight of material being processed may cause enough flexing in the filters to provide the self cleaning function, without the need to use a flapper 7. The arrangement may be of particular use in cleaning a rotary filter processing mixed wet and dry materials.

Description

Filtration Device

Field of the Invention

This invention relates to a device for filtering objects by size, and in particular is concerned with rotary mesh filters.

Background to the Invention

Many industrial and agricultural processes require waste or other products to be sorted by size. It is often useful to sort stone or ceramic rubble by size, so that it can be used as in building, for example as ballast or hardcore. Waste that has been consigned to skips can also usefully be sorted to reduce the amount that must be confined to a landfill, with a size based filter helping to separate biodegradable elements. Sorting by size can also be used to process sand or gravel, as well as lumber mill by-products, seeds and other organic products such as compost.

Various systems exist to sort inanimate objects by size, and they may depend upon some form of sieve, essentially pouring objects onto a network of holes and seeing which ones are small enough to fit through. For example, ore extracted by mining is often cleaned in a rotating barrel sieve, or trommel, with excess earth and other deposits being washed away through the holes of the trommel. This sort of system is dependable when the objects to be sorted are reliably discrete. However, when sorting objects that are capable of adhering to each other or the sieve, a system such as this will frequently become clogged. If the rubble to be sorted is wet, the smaller pieces of rubble and earth may form a mud which will block the sieve and make it impossible to continue until the machine has been cleaned at great expense of time and effort.

Therefore a system capable of sorting objects by size, but which was also capable of self cleaning and hence avoiding blockages, would be very desirable.

Summary of the Invention

Accordingly, this invention provides a rotary mesh filter, part at least of whose mesh is inherently elastic.

This invention further provides a device for filtering objects by size. The device comprises: (i) a supporting structure; (ii) a frame enclosing a space and attached to the supporting structure; and (iii) at least one elastic member provided with at least one hole, the elastic member being attached to the frame. The frame is arranged so as to rotate with respect to the supporting structure, in use.

In this way the invention provides a simple device for filtering objects placed within the frame. Sufficiently small objects will drop through the holes in the elastic member as the frame is rotated. Because the elastic member is elastic, it will deform under its own weight as the frame is rotated, allowing any objects caught within the elastic member to fall back into the frame. Therefore the system is self cleaning, avoiding the need for extensive and frequent maintenance when processing difficult objects such as wet organic materials.

The device can be adapted to process objects of any size and shape, simply by varying the size of the objects and the size of the holes in the elastic members. Applications for the invention include the processing of sawdust, rubble, earth, domestic waste, compost, and any other objects that need to be sorted by size. The supporting structure and the frame are typically formed primarily with steel, but any other suitably strong and stiff material can be used.

It may be that the device further comprises: (iv) a deformation member attached to the supporting structure, wherein the deformation member is arranged so as, in use, to deform the elastic member at a point which is substantially fixed with respect to the supporting structure. Therefore, as the frame is rotated, the elastic member is deformed by the deformation member. It may be that the deformation member is capable of bending so as to allow the frame to rotate.

In a presently preferred embodiment, the deformation member is formed from rubber, as this material can be both stiff enough to deform the elastic members and flexible enough to allow the smooth rotation of the frame. Furthermore, a deformation member formed from rubber does not have any sharp edges which may damage the elastic member.

However, in alternative embodiments the deformation member may comprise metal, wood, or any other suitable material or combination of materials such as rubber adhered to a metal frame.

Typically, the deformation member is fixed rigidly with respect to the support structure, and arranged so as to apply pressure to that part of the elastic member on the outside of the frame. This pressure causes the elastic member to temporarily deform, enlarging the size of the holes and allowing any objects trapped in the elastic member to fall out. It is advantageous to locate the deformation member near the top of the support structure, so that the objects falling from the deformed elastic member will fall back into the frame.

Alternatively, it may be that the deformation member is hingedly joined to the supporting structure. Where this is the case, typically part of the deformation member will rest upon that part of an elastic member to be deformed, in use. Therefore it is the weight of the deformation member that causes the elastic member to deform.

It may be that the frame is substantially prismatic; a polyhedron with two congruent polygonal faces and with all remaining faces parallelograms. Typcially, the device is a trommel, a revolving cylindrical sieve.

It may be that at least one elastic member is substantially planar when not under tension.

In the presently preferred embodiment, a prismatic frame is provided with a plurality of elastic members, each of which comprises a plurality of identically sized holes, and each of which can be replaced separately to aid in maintenance.

Typically an elastic member comprises neoprene rubber. This material is used because neoprene is hard wearing, elastic and available cheaply. However, any sufficiently hard wearing and elastically deformable material can be used, including other forms of rubber.

Brief Description of the Drawings

An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is a diagram showing one embodiment of the invention in profile; and Figure 2 is a diagram showing the same embodiment of the invention from a different angle.

Detailed Description of Exemplary Embodiments

Figure 1 and Figure 2 show a trommel 1 according to a first embodiment of the invention.

The trommel 1 is suitable for filtering compost. The trommel 1 comprises a cylindrical frame 2 which is provided with ten neoprene screens 3. The neoprene screens 3 comprise a mesh, a network of holes through which the smaller fragments of compost can pass.

The cylindrical frame 2 rests on two freely rotating wheels 4 and two drive wheels 5. The drive wheels 5 are connected to a motor. When the motor is running, the drive wheels 5 rotate, which in turn causes the cylindrical frame to rotate. In use, compost is loaded into the cylindrical frame 2 of the trommel 1, and the cylindrical frame 2 is rotated. This motion keeps the compost turning over inside the trommel 1, so that different fragments of compost are brought into contact with the neoprene screens 3. The smaller fragments can the fall through the mesh in the neoprene screens 3 into the container 6 placed below the trommel 1.

The trommel also comprises "flapper" 7, a stiff rubber member. As the cylindrical frame 2 is rotated, the neoprene screens 3 are brought into contact with the flapper 7, causing them to deform as shown in figure 1. As the neoprene screens 3 are stretched by the flapper 7, the holes in the mesh are enlarged, allowing compost that has become lodged in the mesh to fall out. Since the flapper 7 scrapes the outside of the neoprene screens 3 it also serves to directly push any fragments of compost that extend beyond the surface of the neoprene screen back through to the inside of the cylindrical frame 2.

The cylindrical frame 2 comprises ten beams 8 joining two circular end pieces 9. The flapper 7 is flexible, so that as the cylindrical frame 2 rotates, the flapper 7 will bend out of the way to allow the beams 8 to pass.

In use, the trommel 1 can be fitter with two plugs, fitted to the circular end pieces 9, which prevent the compost from falling out the ends of the trommel.

In use, the trommel 1 stands on four legs 10, so that it can be elevated over the container 6. These legs 10 can be adjusted to raise and lower the trommel 1, and removed completely when the trommel 1 is being transported.

In a second embodiment of the invention, a trommel comprises a cylindrical frame and neoprene screens, but no flapper is provided. Instead, the neoprene screens deform under their own weight as the drum is rotated, causing the holes in the mesh of the neoprene screens to change shape, allowing objects caught in the mesh to escape.

In a third embodiment of the invention, a trommel comprises a cylindrical frame and neoprene screens, and a weighted member is hingedly joined to the trommel at the same location as the flapper 7 in the first embodiment shown in figures 1 and 2. In use, the weighted member rests upon the neoprene screens as they rotate, and the weight of the weighted member causes the neoprene screens to deform.

Claims

Claims 1. A rotary mesh filter, part at least of whose mesh is inherently elastic.
2. A device according to claim 1, suitable for filtering objects by size, the device comprising: (i) a supporting structure; (ii) a frame enclosing a space and attached to the supporting structure; and (iii) at least one elastic member provided with at least one hole, the elastic member being attached to the frame, wherein the frame is arranged so as to rotate with respect to the supporting structure, in use.
3. A device as claimed in claim 2, wherein the device further comprises: (iv) a deformation member attached to the supporting structure, wherein the deformation member is arranged so as, in use, to deform the elastic member at a point which is substantially fixed with respect to the supporting structure.
4. A device as claimed in claim 3, wherein the deformation member is flexible and, in use, the deformation member bends as the frame rotates.
5. A device as claimed in claim 3 or claim 4, wherein the deformation member is hingedly joined to the supporting structure.
6. A device as claimed in claim 5, wherein part of the deformation member rests upon that part of an elastic member to be deformed, in use.
7. A device as claimed any preceding claim, wherein the frame is substantially prismatic.
8. A device as claimed in any preceding claim, wherein the device is a trommel.
9. A device as claimed in any preceding claim, wherein at least one elastic member is substantially planar when not under tension.
10. A device as claimed in any preceding claim, wherein the elastic member comprises a plurality of identically sized holes.
11. A device as claimed in any preceding claim, wherein the frame is driven, and the frame rests on the driving means.
12. A device substantially as hereinbefore described with reference to the Figures.