mml
● ● ● Particularities: a small boiler using new technology to burn shredded wood in a learning environment.
The wood energy Trail
● ● ●
Chéseaux-Noréaz : wood-fired heating to protect the environment
Chéseaux Noréaz
Vaud region
Photo AJENA
The Pro Natura centre in Champ-Pittet decided in 1996 to change its heating system. The decision was prompted by the expansion of
The château and the feeder silo
Photo AJENA
the site and the desire to change to a more environmentally friendly system. The centre has many varied activities, such as photographic exhibitions, audio-visual displays, guided visits of the site and the surrounding area, learning activities and teaching of traditional skills. The heating system provides warmth via the existing network for the château, including the restaurant and the large display halls, as well as for the buildings around the château and the extension with its large rooms.
The boiler
Information on the community • Altitude : 430 m, • Population : 500 inhabitants, • Forest : c. 150 hectares.
Fuel supply To guarantee the delivery of high-quality fuel, a contract has been drawn up between the fuel supplier and the director of the centre, in which the shredded wood is paid in accordance to the amount of energy it producesthe amount of kWh coming out of the boiler. The amount of energy produced by the boiler is the result of the combustion of 160 m3 of woodchips, which consist of a mixture of 50 % broadleaf and 50 % resinous wood with a moisture content of 30 % of the gross weight. The shredded wood is delivered by a forester based in the region of Fribourg. The silo cover can support the weight of a vehicle, and it opens automatically thanks to a hydraulic jack. The feeder silo has a capacity of 90 m3, and is refilled two or three times a year. At the bottom of the silo are hydraulic scrapers mounted on hydraulic jacks on the silo floor which transfer the shredded wood via two successive worm screws to the boiler.
A new type of boiler The KÖB boiler has an output of 150 kW. It has a combustion chamber with underfeeder screw, and a cylindrical post-combustion chamber for an optimal combustion of the smoke produced. The maximum moisture content permissible is 40 % of the gross weight. Dust particles are extracted by a cyclone before the gases leave via the chimney. This dust is retained in a special container. The ashes produced must still be removed by hand : they are stored in a receptacle which is emptied twice a week. The horizontal smoke flues of the heat exchanger are cleaned once a fortnight. The boiler, placed in an outbuilding near the château, produces at its maximum output for the equivalent of 1,680 hours per year. The energy produced by the wood burned represents the equivalent of 27,000 litres of fuel oil or 28,560 m3 of natural gas.
© ITEBE- july 1999
An appropriate form of heating for an environmental centre
Switzerland