I-001-FI-020-EN
mml
● ● ● Particularity : valorisation of wood shavings and sawdust to heat a dozen studios
The wood energy Trail
Aigle : a small-scale community heating system using waste wood from carpentry Fuel supply
Photo AJENA
The Decosterd carpentry and timber construction company has three employees.
The Decosterd company premises
Photo AJENA
In 1997, the firm decided to install an automatic wood-fired boiler. The aim was to valorise the waste produced during the manufacture of doors, window frames, staircases, and housing frameworks (bits of wood, shavings, dry sawdust). The small-scale installation chosen provides warmth and hot water all year round for two buildings, which are divided into a dozen small flats belonging to the company’s owner. The boiler, situated underneath the workshop, maintains the temperature at an average of 15 °C.
Programme of the Jura Department
Information on the community • Altitude : 450 m, • Population : 7,000 inhabitants.
The fuel used is recuperated from byproducts from the carpentry workshop. Most of the wood is pine. The entire annual production of wood waste (bits of wood and shavings), around 180 m3, is used. For the time being, this amount is not sufficient, and the boiler is topped up with normal firewood. This is ground to obtain the ideal granulometry for optimum combustion. The chips are stored in a silo with a capacity of 50 m3. An extractor fan with sleeve filters takes the wood shavings and sawdust directly into the silo. To transfer the fuel from the silo, two hydraulic extractors bring the fuel into contact with an Archimedes screw which leads to the boiler. The boiler is situated three metres below the silo, which allows the shredded wood to fall into a small hopper before being transferred via another Archimedes screw to the combustion chamber.
A self-operating boiler room The ZIMA boiler, with an output of 60 kW, has an underfeeder screw which takes wood with a gross moisture content of 25 %. The boiler is not equipped with a regulator to ensure that combustion is permanent, but there are always embers which allow combustion to take place easily. The boiler is lit automatically by an electrical resistance system. The combustion chamber is made of refractory ceramic, making it extremely resistant. A cyclone removes the dust from the smoke before it is extracted via the chimney. The ash is cleared manually, but only requires a very short visit every 14 days. The horizontal smoke flues of the heat exchanger only need cleaning every two months. There is also a connection to an oil burner if the need arises. The boiler also provides hot water all the year round (with a water heater of 800 litres).
© ITEBE- july 1999
A small boiler burning shredded wood
The boiler
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