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● ● ● Particularities : a combined heat and power heating system using a buffer tank.
The wood energy Trail
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The Bière barracks : the strategic use of wood energy
Bière
A public decision
Switzerland Vaud region
The Federal Bureau of Armaments and Construction (OFMAC), which replaced the Federal Bureau of Construction (OCF), designed and built this installation with two principles in mind : promotion of a high degree of architectural and technical quality, and consiThe boiler plant
shredded wood is stored in a hangar measuring 4,000 m3. Once transferred to the boiler plant, it is kept in a silo of 800 m3 suspended above the ground and equipped with a travelling crane with a grab arm. The entire system, from the filling of the silo to the transfer of the fuel to an intermediary silo (120 m3, one day's fuel), is automated. The annual consumption of the boilers is estimated at 13,500 m3 of woodchips.
The two wood-fired boilers
derations of the environmental protection and possibilities of energy-saving offered by a global, ecological way of thinking. The boiler plant at Bière kills two birds with one stone : it uses wood not only for heating purposes, but also as a building material.
Photo Bertin 1603 Grandvaux
Information on the site
In the foreground, the heating network expansion system. In the background the turbogenerator.
• Activity : military and fitness training, repair workshop • Altitude : 680 m, • Number of buildings : 37 large buildings (91,100 m2), • Length of network : 3,000 metres.
Fuel supply The fuel used is woodchips, produced and delivered by the community of Bière. The
The boiler plant is connected to a heat and power unit with two Schmid wood-fired boilers, one a hot oil system with an output of 1,800 kW, and the other a hot water system with a capacity of 1,400 kW. The combustion chamber with moveable grates takes fuel with a moisture content of up to 50% of the gross weight. If the need arises also the summer there are two oil-fired boilers of 1,400 kW and 1,000 kW. The turbogenerator, linked to the hot oil boiler, has a minimum output of 300 kW of electricity and 1,440 kW of heat. The installation also has two heat accumulators, each with a capacity of 4 m3, which allow the wood-fired boilers to function at their optimum level. An installation on this scale heats the equivalent of 1,200 four-room flats and provides electricity for the equivalent of 200 four-room flats.
Combining heat and power. The combined heat and power unit consists of a turbine powered by an organic fluid with a high molecular mass. The primary circuit is hot oil which reaches 300°C max. This means it is not necessary to install a high-pressure steam network or a costly water treatment system. The oil exchanges heat with the organic fluid in an evaporator (heat exchanger). This combination of heat and power production is productive every day during the period when heating is required. The annual electricity production is 1,120 MWh on average.
© ITEBE- july 1999
Photo Berrin 1603 Grandvaux
Photo Bertin 1603 Grandvaux
Optimum efficiency for the boiler plant