1 January 1999

Woodchip waste provides plenty of heat and power

By Andy Collings

AN electricity generating plant which uses woodchips as an energy source is now up and running in Northern Ireland.

Different from other units now operating in the UK, it employs an automatic feed system which means the plant can be operated continuously.

Based at the Blackwater Valley Museum at Benburb, output from the B9 Energy Biomass wood fuelled combined heat and electricity generating plant is rated at 200kW – sufficient power for about 400 homes – with waste heat used by the museum.

B9 Energy Biomass, set up in 1995 to develop and operate plants using sustainable local wood fuel, formed a joint venture with Swedish companies SMP and Exergetics to design the unit.

Woodchips are delivered to the plant by lorry twice a week, from local sawmills, and tipped into an enclosed storage area. From there, they are fed automatically into two units where waste heat from the engine cooling system dries the chips. On arrival at the gasifier, the chips are heated in a restricted flow of air which converts them into a combustible gas. This gas contains hydrogen, carbon monoxide and methane – the combustible elements – and CO2 and nitrogen.

The gas is then cleaned, cooled and mixed with air before being fed into the engine, a 13.8-litre, 6-cylinder compression ignition unit. Gas entering the engine is first mixed with a small amount of diesel fuel (about 10%) to ensure ignition and, once fired up, the engine then powers the generator.

During operation, the engines exhaust creates a significant amount of heat which is recovered by diverting the gasses through heat exchangers, with the resulting hot water pumped through the museums radiators.

Computer controlled, the plant has been designed to operate with little supervision for six days at a time, after which charcoal deposits need to be removed from the gasifier.

While wood chips are the current source of fuel, B9 Energy believes Northern Irelands potential to produce willow coppice could eventually be exploited. The spin-off, it says, could be a useful and profitable diversification for local farmers – bearing in mind that the vast majority of willow harvesting takes place during the winter months. &#42

Better control for spreading at boundaries

LATEST development from the Amazone fertiliser spreader stable, based at Pillaton, Saltash, Cornwall, is the twin disc ZA-M Hydrotron, which features electronic spread rate control for boundary spreading.

Control is through the companys AMASET system, which allows the driver to pre-select spreading to the left or right hand sides for normal or boundary spreading. It is the first time, says Amazone, that this facility has been available on a fertiliser spreader.

In the field, on the first bout the operator presses a button on the control unit to close the feed shutter to the relevant disc; pressing another button on the return run reverts the machine to normal spreading.

Where the spreading width is reduced, the application rate is automatically adjusted to maintain the preset spreading rate.

To assist the driver, operational status of the spreader – whether set for boundary spreading, normal field application or short work – is displayed on the in-cab monitor. &#42

Gas dryers may be safer option

A NEW range of gas-fired crop dryers has been launched by Colchester-based Master Driers.

Key feature of the new models, which have capacities of 6t, 8t, 10t and 12t, is use of a new triple jet burner system that is claimed to offer increased safety and temperature flexibility.

Basically three independently controlled flames, the first takes 30% of the total, the second can be shut down by a switch on the control panel, and the third flame is controlled automatically.

It is an arrangement, say Master Driers, which allows precise thermostatic control of the drying process using gas levels from 30% through to 100%.

In addition, burner performance has been enhanced by mounting the vapouriser some 25cm (10in) away from the burner head. Operated in conjunction with an adjustable deflector, the vapouriser performs more efficiently by maintaining correct operating temperatures. Gas which is not vapourised correctly burns less efficiently and results in increased fuel consumption. Each drier is available in one of three builds – mobile with retractable screen and fold-down auger, static in-barn with fixed screen, and as the Mastermatic version, which offers fully automatic operation.

Master Driers, recognising that working batch driers are not the most dust free machines, has also introduced a dust extraction system designed to remove up to 80% of dust from around the drier.

An electric or belt driven fan fitted to the front of the drier sucks dust away from the top of the central recirculating auger – the source of most dust creation – and blows it to a container. A cyclone can be specified to help with dust/air separation at the delivery point.

Prices start at about £14,600. &#42

Looking perhaps more like an industrial dump truck than a farm trailer, there is no denying the robust build of the latest trailer to be produced by TBF Thompson of Coleraine, Co. Londonderry. Load capacity is 14t and the hydraulically operated tailgate is designed to ensure speedy tipping cycles. Available as a low speed (20mph) build with hydraulic brakes, or as a high speed version complete with ABS and hydraulic or air brakes, prices start at £10,500.