A COMPOSTING VESSEL

The present invention relates to a composting vessel, a composting vessel roof and a method of accessing a composting vessel.

BACKGROUND OF THE INVENTION

There is increasing demand for large scale composting facilities to compost household and other material at centralised facilities, which receive material by the lorry load from, for example, council kerb side collections.

These facilities usually comprise a plurality of composting vessels, which can be entered by large vehicles placing and moving the material such as lorries and front-end loaders (large tractor-type vehicles with a bucket at the front).

The vessels should be low, typically under 4m, in order to conform to planning regulations and to be less intrusive on the environment. They should also be easily accessible to the large vehicles moving the compostable material around, which are typically over 4m high. Such facilities must comply with the Animal By- Products Regulations 2003 (ABPR), to facilitate pathogen kill and to prevent access to birds and rodents. The vessels should be resistant to corrosion in the very hostile environment created by the composting material.

Various arrangements of vessel have been proposed. Known in-vessel composting roof systems comprise a variety of technologies.

One such vessel 1 , supplied by Agrivert Ltd of Chipping Norton, Oxfordshire, UK ₁ is illustrated in Figure 1. The vessel 1 comprises opposing side walls 2 and a roof 3 mounted to the side walls 2. The roof 3 is formed in two halves 4, one mounted by a hinge to each side wall 2. In the closed position (not shown), the two halves 4 of the roof 3 meet in the middle of the vessel 1. In this way, compostable material in the vessel 1 is covered. In the open position (illustrated in Figure 1), the two halves 4 of the roof are raised to project upwardly from the vessel 1 , from their respective hinges, uncovering the compostable material in the vessel 1. A frame 5 projects upwardly from each side wall 2 and supports a rope and pulley arrangement 6 for raising and lowering each half 4 of the roof 3.

A door 7 is connected by a hinge to each side wall 2. With the roof 3 in the open position, the doors 7 are opened (as shown in Figure 1) and large vehicles 8, taller than the vessel 1 in the closed position, can enter the vessel 1 to add compostable material to or remove it from the vessel 1.

The vessel 1 is made from aluminium, concrete and Goretex (registered trade mark).

This arrangement presents a number of problems. The composting area is exposed to the surrounding environment when the roof is open. This means that, for example, rain and snow can fall on the compost when the roof is open adversely affecting the composting process within the vessel. Furthermore, people and vehicles working inside the open vessel are exposed to the rain and snow. Also, when the roof is in the open position, there is nothing to prevent odour rising and leaving the vessel and birds can easy access the inside of the vessel. Furthermore, the Goretex (RTM) material used in the vessel allows odours to escape from the vessel even when the vessel is in the closed position.

Wasteology Systems Limited of Suffolk, UK produce vessels 10 of the type illustrated in Figure 2, which have a retractable roof 12. The vessels 10 have side walls 14 made of concrete and a roof 12 of a tent-like construction. The tent- like roof 12 is made by Copperfield Engineering of Kenton, Stowmarket, Suffolk. The roof 12 has rigid cross members 16 extending between the side walls 14, which are covered in flexible sheeting 18. The flexible sheeting 18 is a PVC (polyvinylchloride) coated material. Wheels (not shown) are located at the base of the roof, which are located on rails (not shown) at the top of the side walls 14. In the closed position, shown in the right hand vessel 10 of Figure 2, the rigid cross members 16 of the roof are spaced apart from one another along the length of the vessel so that the flexible sheeting covers the vessel. In the open position, shown in the left hand vessel 10 of Figure 2, the rigid cross members 16 are moved together at one end of the vessel by pulling on ropes at the end of the vessel. This causes the wheels at the base of the roof to roll along the rails, so that the flexible sheeting is folded to the end of the vessel by concertina-type folding.

In the open position, large vehicles taller than the vessel 10 in the closed position are able to enter the vessel.

This type of retractable roof has a number of problems. It is not sealed, so that odour and bio-aerosols can escape. Furthermore, the composting area is exposed to the surrounding environment when access is provided for vehicles. As with the Agrivert system described above, this means that rain can fall on the compost when the roof is open adversely affecting the composting process within the vessel and more odour can leave the vessel when it is open. The rain can also fall on the people working inside the vessel. In addition, the sheeting tears, the wheels rust and jam, and the ropes break. For these reasons, the system frequently requires repair and maintenance and is susceptible to the possibility of contravention of the ABPR if the roof jams open or tears allowing bird or rodent access. Also, this type of roof does not enable vehicles to drive through the vessel.

Cambridge Recycling Services Ltd of Wilburton, Cambridgeshire, UK produces composting vessels 20 with retractable roofs 22 as illustrated in Figure 3. Each vessel 20 comprises two opposing side walls 24 and a roof 22. The roof comprises flexible polyester sheeting 26 between the side walls supported by rigid cross braces 28, which extend between the side walls and engage with guides at the tops of the side walls. One end 30 of the roof is attached to a rotatable drum at the rear of the vessel. There is an entrance for a vehicle at the front of the vessel. In the closed position, shown in the vessel 20 in the left hand side of Figure 3, the sheeting 26 covers the compostible material inside the vessel. In the open position, shown in the vessel 20 in the right hand side of Figure 3, the sheeting 26 has been rotated around the drum so that the roof is moved back and the compostible material in the vessel is uncovered. In this way, a vehicle higher than the vessel with the roof closed can enter the vessel to place or remove compostible material from the vessel.

This retractable roof system suffers from similar problems to the Wasteology Systems Limited retractable roof system described above, as the retraction system has a tendency to jam, the sheeting can tear and the vessel does not allow vehicles to drive through it.

Covered Systems Ltd of Ipswich, Suffolk, UK produce a composting vessel of concrete 32, illustrated in Figure 4, comprising fixed side walls 34 and a fixed roof 36 extending between the side walls 34. The vessel 32 is sufficiently high so that high lorries and front end loaders can enter and leave the vessel 32 with the roof fixed in place. For protection and insulation, each vessel is insulated inside using foam, which is then painted. This design causes a number of problems. First, as the fixed roof 36 has to be high enough (typically 8m high) to allow for the loading and unloading of vehicles in the vessel, it can fall foul of planning regulations. Furthermore, the resulting void space between the top of the compost and the roof inhibits the composting process.

Cambridge Recycling Services Ltd also produce a vessel of concrete (not illustrated) which comprises fixed side walls and a fixed flat roof extending between the side walls. This design causes a number of problems. Firstly, the roof is fixed at the height of the walls, typically 5m high. This makes access for vehicles extremely difficult. Furthermore, it is a harsh, dark, poorly ventilated, and inhospitable environment in which to work.

Compost Systems Trade GmBH of Dittersdorf, Germany also produce a fixed- roof vessel similar to that of Cambridge Recycling Services Ltd. This vessel suffers from the same working environment disadvantages as the Cambridge Recycling Services Ltd fixed-roof system described above.

These prior art systems thus all entail problems that adversely effect the operation of composting vessels and/or their composting performance and/or their environmental impact. The invention aims to provide a solution to these problems.

SUMMARY OF THE INVENTION

The invention is defined in the appended independent claims to which reference should now be made. Advantageous features are set forth in the dependent claims.

A preferred example of the invention is described in more detail below and takes the form of a composting vessel comprising side walls; an entrance for a vehicle;

a roof; and a drive mechanism. The drive mechanism moves the roof along a vertical axis between a closed position in which the roof contacts the side walls and closes the vessel, and a raised position in which the roof is spaced vertically from the side walls.

A composting vessel embodying the present invention may provide some or all of the following advantages.

With the roof raised, it allows easy access for loading and unloading of the composting vessel, by large vehicles such as lorries and front-end loaders and it improves working conditions, as work will be under cover when access is provided for vehicles into the vessel. In addition, compost is not exposed to rain or snow while loading or unloading the vessel.

There are no hanging sheets for the loading vehicles to tear, no ropes to break and no wheels to jam.

The roof lifting mechanism is geared to ensure even lifting of the roof to avoid jamming. If the roof should jam, a simple sheeting drape would ensure continued compliance with the ABPR.

With the roof closed, it seals to prevent the escape of odour. It also provides a very small void space above the compost, which enhances the composting process and aids temperature control.

In addition, the vessel is fully enclosed in compliance with ABPR. It may be robust and resistant to corrosion.

It is also easy to operate and can be operated at the touch of a button.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 (prior art) is a front view of a known composting vessel described above;

Figure 2 (prior art) is a perspective view of two composting vessels of another known type described above;

Figure 3 (prior art) is a perspective view of two composting vessels of a further known type described above;

Figure 4 (prior art) is a perspective view of four composting vessels of a yet further known type described above;

Figure 5 is a perspective view of a composting vessel embodying the present invention in a closed position;

Figure 6 is a perspective view of the composting vessel of Figure 5 with the roof in a raised position;

Figure 7 is a cross sectional view of a part of an aeration system of the composting vessel of Figures 5 and 6;

Figure 8 is a perspective view of a concrete block used for the side walls of a further embodiment of a composting vessel embodying the present invention;

Figure 9 is a perspective view of a mould for making the concrete block of Figure 8;

Figure 10 is a perspective view of two side walls of a composting vessel embodying the present invention using concrete blocks of Figure 8; and

Figure 11 is a perspective view of a roof drive mechanism for use by a composting vessel embodying the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A composting vessel 40 embodying the invention will now be described with reference to Figures 5 and 6.

The composting vessel 40 is adapted to contain compostable material and to allow tall vehicles to enter the vessel to place and remove the compostable material.

The vessel 40 is rectangular in plan view. It comprises side walls 42, 44 along two opposing sides, an entrance 46 for a vehicle (not shown) at one end, and an exit 48 (shown in Figure 6) for a vehicle opposite the entrance 46. The entrance 46 and exit 48 are closable by doors. The vessel has a rigid roof 50. The vessel has a drive mechanism for moving the roof 50, as a single integral unit, along a vertical axis 52 between a closed position in which the roof contacts the side walls 42, 44 and closes the vessel (shown in Figure 5), and a raised position in which the roof 50 is spaced vertically from the side walls 42, 44 (shown in Figure 6).

Typical dimensions of the vessel 40 are as follows. As shown in Figure 5, the length A of the vessel is between 10m and 20m, and preferably 14m. The width B of the vessel is between 5m and 15m, and preferably 8m. The height C of the side walls of the vessel is between 2m and 5m, and preferably 3.2m. The side walls have a thickness E of between 100mm and 1m, and preferably 500mm. As shown in the example of Figure 6, the roof 50 is raisable by a distance F of 2m (distance F could be between 1 and 3m), from side walls that are 3.2m high, which means that the total height G of the vessel is 5.2m when the roof is in the raised position.

The roof 50 slopes downwardly from its centre, apex or ridge 54 towards each side wall 42, 44. Gutters are located at the tops of the side walls. The gutters slope downwardly, along their respective side wall. Rainwater falling on the roof 50 flows down the roof into the gutters and down the gutters towards the exit or entrance side of the vessel (depending on the direction of the slope of the gutters) for disposal or use.

The vessel 40 has a base of concrete, to which the side walls 42, 44 are fixed as follows.

The side walls 42, 44 are of a concrete block construction, in the form of concrete blocks or cast concrete blocks (which may or may not be coloured). Each of the blocks has spaced apart holes, typically two holes spaced apart by 500mm (the holes could be between 100mm and 1m apart). Bars or rods of steel are located in a concrete pad forming the base of the vessel 40 and the bars pass through the holes in the blocks forming the side walls 42, 44. The bars project upwardly

from the base, through the whole height of the side walls. The free ends of the bars are threaded. The threaded free ends of the bars are located through rigid metal channels 56 which extend along the upper edges of the side walls. Nuts on the free ends of the bars secure the channels and blocks in place. The gutters are located on the channels.

The roof 50 is made from a frame covered in sheeting 58 of twin walled construction.

The frame of the roof 50 is made from stainless steel fabricated parts (steel or coated steel could be used) attached together by bolts and, in particular, stainless steel bolts. The sheeting 58 is a plastics material, such as polycarbonate.

The upper edge 62 of the side walls 42, 44 comprises a sealing surface 64 (shown best in Figure 6), such as a rubber seal or heavy-duty rubber seal or similarly tactile material, which the roof 50 contacts in order to seal the vessel 40. Alternatively or additionally, a sealing surface may be provided on the edges of the roof.

The edges of the polycarbonate sheets at the apex 54 of the roof 50 are sealed together by a seal of rubber or heavy duty rubber.

A pair of doors is located at each of the entrance 46 and exit 48 of the vessel 40. At the entrance 46, one door 66 of a pair is mounted by a hinge to the entrance end of one side wall 42 and the other door 68 of the pair is mounted by a hinge to the entrance end of the other side wall 44. At the exit 48, one door 70 of a pair is mounted by a hinge to the exit end of a side wall 42 (see Figure 6) and the other door of the pair (not shown) is mounted by a hinge to the exit end of the other side wall 44. The doors 66, 68, 70 are shown closed in Figures 5 and 6. The doors 66, 68, 70 can be opened outwardly, by rotation of the hinges. The construction of the doors is double skinned, insulated steel.

The upper or top edge of the doors and/or the roof edge have a sealing surface or rubber seal for sealing the edge of the roof 50 and the edge of the doors together.

The drive mechanism for raising and lowering the roof 50 is in the form of screw jacks 72. The screw jacks 72 are located within the side walls 42, 44, close to the ends of the side walls. The example of Figures 5 and 6 comprises two screw jacks 72 located within each side wall. For support, the screw jacks 72 are connected to the channels 62, which extend along the tops of the side walls, and to the side walls 42, 44 by the steel bars. Each screw jack 72 comprises a threaded shaft, which projects upwardly from the top of each side wall. The threaded shafts extend by a distance D of between 1m and 4m, and preferably 2m, from the tops of the side walls.

Guides or stabilisers, which prevent the roof 50 from moving out of line during raising or lowering also project upwardly from the side walls 42, 44. The guides are in the form of rods 74, which are supported by and project upwardly from the channels 62 at the top of the side walls. The guides are attached to the channels of the side walls or the walls by bolts. The guides are located at the corners of the vessel 40, outwardly of the screw jacks 72.

The roof 50 is located by the screw jacks 72 and the guides. The roof 50 has through holes 76 at each corner through which the guides project. A through hole 78 for the threaded shaft of each screw jack 72 is also located at the edge of the roof 50, spaced from each corner of the roof.

A drive system (not shown) for each screw jack 72 is located in an underground service tunnel or on or above the ground. Typically, the drive system comprises an electric motor. The electric motor drives a gearbox, which rotates the threaded shaft of each screw jack. Buttons (not shown) are electrically connected to the electric motor. Pushing the buttons causes the electric motors to rotate the screw jacks in one or the other direction.

The vessel 40 has an aeration system 80, which is shown in Figure 7. The aeration system 80 comprises a steel or plastics channel 82, which is sunk into the concrete pad or base of the vessel 40. The channel 82 has a planar base 84 with sides 86 extending perpendicularly from it. A channel insert 88 of plastics material is located in and extends along the channel 82. The channel insert 88 has a wall with a roughly inverted "U" shape cross section. The free ends 90 of the wall of the insert 88 rest at the join of the base and sides of the channel. The

channel insert is of such a shape such that it is properly seated within the channel. The channel insert has through holes or slits through the wall through which air is emitted. The through holes are spaced apart by between 250mm and 1 m and preferably 500mm along the length of the insert. The width of the channel H is between 100mm and 200mm and preferably 150mm. The height of the channel I is between 50mm and 100mm and preferably 75mm. Fans (not shown) inject and exhaust air through the channel 82. The aeration system 80 may be controlled automatically or manually.

In use, in order to place compostable material into the vessel 40, first the roof 50 is raised by pushing the relevant button. This causes the electric motors of the drive system to rotate and thus the threaded shafts of the screw jacks 72 are rotated. The rotating threaded shafts each engage with the corresponding through hole 78 in the roof, such that the roof is raised. The entrance doors 66, 68 are then opened. A vehicle or vehicles carrying the compostable material can then drive into the vessel 40 to fill it with the compostable material up to a height level with or below the tops of the side walls 42, 44. It should be noted that the vehicle and the compostable material are under cover when the vehicle is in the vessel 40 even though the roof 50 is raised. The vehicle then leaves the vessel 40 by the entrance doors 66, 68. The entrance doors are closed. A button is then pressed. This causes the electric motors to rotate the threaded shafts of the screw jacks 72 in the opposite direction to when the roof was opened and thus the roof is closed. The compostable material is then allowed to compost. It should be noted that the vessel is sealed and there may advantageously be little or no air between the compost and the roof during composting.

Once the material has composted, the exit doors 70 at the other end of the vessel 40 are opened. The roof 50 is raised as described above. A vehicle enters the vessel 40 to remove the compost.

When constructing the vessel 40, the structure of the doors 66, 68, 70 and roof 50 is constructed off-site. The polycarbonate sheet is fixed to the frame of the roofs, once the frames have been assembled. This allows for efficient transportation of the components making up the vessel 40 to its site.

In alternative embodiments, the vertically-movable roof 50 may be driven in any convenient manner. For example, it could be raised and lowered using one or more hydraulic motors. A rope and pulley system could be used. A worm drive could be used as part of the mechanism to operate the roof.

More than one, for example two, underground service tunnels may be provided. The or each service tunnel may also contain a ventilation system for the vessel 40.

The example vessel described herein comprises a separate entrance and exit for vehicles. Such a "drive through" vessel allows for material to be unloaded from vehicles entering the vessel through the doors at one end and loaded onto vehicles entering the vessel through doors at the other. Alternatively, the vessel could comprise only one entrance. In this case, compostable material would enter and leave the vessel through the same door. With this arrangement there would be a fixed wall (of the same construction as the side walls 42, 44) opposite the entrance 46. The drive system for the roof could be located at or above ground level behind this fixed wall or on the rear fixed wall, external to the vessel.

Another composting vessel embodying the invention will now be described with reference to Figures 8 to 11. It is similar to the embodiment of Figures 5, 6 and 7, and like features have been given like reference numerals.

In this embodiment, the sidewalls 42,44 are made from concrete blocks 100. Each block has integral sidewalls 102,104,106,108 forming a one-piece cuboid shape with a cuboid through hole 110 through it. That is, a short tube or thin wall, straight sided enclosure around a central void or through hole. In this example, the wall thickness is 150mm, but the wall thickness could be between 100mm and 200mm. Each block weighs around 0.2 tons in this hollow form.

At least some of the blocks have through holes 112 located in one of the longitudinal side walls of the block 100 to house pipes for an aeration system (not shown) for the composting vessel. In this example, two through holes are shown, but between one and four through holes could be provided. This block construction, with relatively thin side walls, is easy to cut through to make through holes in the side walls.

The blocks are manufactured on the site where the composting vessel is to be built. This is to save on transportation costs as the blocks are heavy and this approach also has less environmental impact.

Each block is made in a mould 150 as illustrated in Figure 9. The mould 150 has two sets of side walls 152, 154 of sheet steel located one within the other forming a cavity 156 between them. Each of the sets of side walls 152, 154 forms a cuboid with a through hole through it. Each forms a short tube or thin wall, straight sided enclosure around a central void. The mould has a sheet steel base (not shown), which prevents concrete from falling out of the bottom of the mould. The mould has reinforcing bars or struts 158,160,162 between both the inner and outer side walls 152,154 to prevent the side walls from deforming under the weight of the concrete. In this example, there is one reinforcing rod 160 extending transversely across the side walls of the inner portion 154. Two reinforcing rods 158,162, on either side of the inner portion reinforcing rod, extend transversely between the side walls of the outer portion 152. These reinforcing rods locate in notches in the upper edges of the outer portion 152. One of the outer portion reinforcing rods 162 has an angled or L shape cross section. The other reinforcing bars 158,160 have square cross sections with a downwardly projecting lug 162 at each end.

Projecting ribs or flanges 164 extend longitudinally along the outer side walls of the mould for further reinforcement.

The outer side walls 152 of the mould have tags 166 extending from their ends at the same angle from each side wall. Through holes 168 extend through the tags. Fasteners (not shown) in the form of screw threaded bolts extend through the through holes and nuts tightened to the bolts hold the outer side walls together.

To make a block such as that illustrated in Figure 8, a layer of oil is applied to the inner steel surfaces of the cavity 156 to prevent concrete sticking to the mould. Liquid concrete is poured into the mould 150 into the cavity 156 formed between the sets of side walls 152,154. A steel hook or hooks are pushed into the upper exposed surface of the concrete. The concrete is allowed to set. The concrete block is removed from the mould by removing the reinforcing rods 158,162 which

extend between the outer side walls of the mould and then lifting out the finished concrete using the hook or hooks extending from the surface of the block.

Holes are cut through one of the longitudinal side walls of some of the blocks as required.

The moulded blocks 100 are assembled to form the side walls 42,44 of the composting vessel as shown in Figure 10. The blocks 100 are arranged in rows 200 one above the other to form the sidewalls 42,44 of the composting vessel. Neighbouring blocks are held together by mortar. The bottom rows 202, in this example the two bottom rows, form foundations for the side walls. The mortar joins 204 between the blocks of the rows forming the foundations are collinear. The joins 206 between the blocks of neighbouring rows of the upper rows are spaced apart or offset by half a block-length. In this way, the cavities of the vertically spaced apart blocks 100 interconnect to form a large cavity through the whole height of each side wall 42,44.

The blocks with holes in their longitudinal side walls have the holes facing inwardly. In this example, blocks with through holes are located only in some of the rows of blocks, in this example, every fourth row. The blocks with through holes are also only in some of the blocks of each row, in this example, every fourth block in a row.

Pipes are located in the through holes and through the blocks to form part of the aeration system for the composting vessel.

Liquid concrete is poured into the sidewalls to fill the cavities of the blocks. The cavities are filled will liquid concrete after some rows have been completed, typically, every third row of blocks. A concrete filled block has a mass of about 0.5 tons.

The aeration system operates as follows. Air is pushed through the composting material from a service tunnel (not shown) underneath the composting vessel. This air percolates through the composting material and then through the through holes and pipes in the sidewalls and back into the service tunnel in a cycle. When the oxygen level in the service tunnel reaches a predetermined level, as

sensed by an oxygen sensor, fresh air is introduced into the system, which is vented out through a bio-filter.

An alternative drive mechanism for raising and lowering the roof of the composting vessel is illustrated in Figure 11 It is similar to that of Figures 5, 6 and 7, and like features have been given like reference numerals. Like the embodiment of Figures 5 and 6, the drive mechanism comprises screw jacks 72. In contrast to the embodiment of Figures 5 and 6, the screw jacks are fixed to the roof 50. Each screw jack 72 comprises a threaded shaft 302, which projects downwardly into a side wall 42,44 , where it locates within a tube 306 in the side wall. In the example of Figure 11, two screw jacks are provided spaced apart along each side of the roof. Other numbers of screw jacks could be used, for example three screw jacks spaced apart along each side of the roof. The latter arrangement has the advantage of reducing bowing of the roof when it is in the raised position which can result as the roof is so long (typically around 14m long). The screw jacks are driven by electric motors (not shown) located at one end of the side walls. In this example, one electric motor is used to drive the screw jacks on each side of the roof and a control system is provided to synchronise the motors so that both sides of the roof are raised simultaneously.

To raise the roof 50, the electric motors are switched on so that their axles rotate in one direction and the threaded shafts rotate so that they project further outwardly from the roof. Similarly, to lower the roof, the electric motors are switched on so that their shafts rotate in the other direction and the threaded shafts project less from the roof.

Embodiments of the present invention have been described with particular reference to the examples illustrated. However, it will be appreciated that variations and modifications may be made to the examples described within the scope of the present invention.