Weima Shreds Costs in Hammonds’ Waste-to-Energy System
Hammonds Furniture called in Weima to shred its wood-based waste as part of a £500,000 investment in a sophisticated waste-to-energy system. It estimates it will save £81,000 a year in landfill costs by using the shredded material to fuel a wood fired boiler to produce factory space heating.
It used to dispose of wood waste into open skips which were sent to landfill, but this was becoming increasingly expensive, particularly with the arrival of the landfill tax.
To overcome the problem and cut down on energy costs, it recently installed a state of the art waste-to-energy system, supplied by Modern Energy Systems. It is based on a two stage combustion system close coupled to a Danish Danstoker boiler with a 1,500 kw output. It is capable of burning up to 50 tons per week of wood waste to produce hot water for the heating system that serves the company’s 100,000 sq ft main factory, with capacity for expansion.
After initial discussions with three shredder companies Hammond selected a WLK 15/55 model from leading German manufacturer Weima, purpose-designed for the woodworking industry. It was supplied and commissioned by the company’s UK sales and service operation, Weima UK Ltd, of Corby.
“There were several reasons for picking Weima,” says Hammonds’ Production Engineering Manager, Keith Aubrey. “We needed a shredder that would guarantee a minimum throughput of 30 tons a week in order to keep the boiler going and I particularly liked its advanced rotor system, which makes the best use of the knives, and the efficient way that it chips.”
Hammonds used to fill up to six 35cubic yard capacity skips with wood waste each week, which is why it expects to achieve savings of over £80,000 annually in skip disposal costs, together with a substantial reduction in fuel charges.
Chipboard and MDF off cuts produced by all the CNC panel saws and routers in the factory are collected in automatic tipping skips. When full they are emptied by fork lift into the shredder’s 2.5 x 2.5m flared hopper opening, specially built to Hammonds’ requirements. Larger reject panels and damaged pallets are also fed in, with the machine reducing everything down to a 15mm chip size, ideal for use as boiler fuel.
The chips are automatically transferred via ducting to a 60 tons capacity silo and then to the boiler. Saw dust extracted from the production machines, which also used to go to landfill, is transported direct to the boiler.
Hammonds placed the shredder outdoors at a central point beside the factory to give easy access from all production areas. Wood waste from a second factory is brought to the shredder in tipping skips on inter-factory vehicles.
Weima supplied a sliding lid to be put over the hopper’s opening when shredding. This has kept the already low noise and dust levels down to a minimum – the shredder works by cutting up waste rather than pulverising it – and has removed the possibility of dust escaping into the air.
Single-shaft Weima WLK automatic shredders have a high torque, low rpm motor, ensuring efficient operation and a long working life. They are available as standard with hopper openings from 1200 m x 1200 mm x 1500mm in size for ease of loading and to suit every size of wood waste recycling operation. They feature Weima’s patented V-rotor system with hardened steel knives and concave ground corners, four times reversible for extra high output.
“Weima suggested we install a machine that had enough spare capacity to cope with additional quantities of waste should we expand the manufacturing facilities in the future, so the shredder can easily handle another 20 tons a week,” says Mr Aubrey. “It’s so well built it should last us for years.”
The waste-to-energy system is a further example of Hammonds’ commitment to the environment and means that over 80% of the waste material it produces is now being recycled. Cardboard and polythene packaging used in customer deliveries are returned to the factory and sent for recycling, as is all PVC material.
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