THE BOREALIS PROCESS
The Borealis wood-power plant operates on the principle of wood gasification with the input of dry wood chips and the output of wood gas. The wood gas feeds the CHP unit (Combined Heat and Power) producing electric and thermal power.
The reactor is at the heart of the system, changing the wood chip fuel into wood gas. At the pyrolysis zone, the wood decomposes and begins reducing from its visible wood state. The fuel is then converted to a coal-like hydrocarbon and transported to the oxidation zone where part of the carbon is burned with injected air at approximately 800°C. As the gases move over the hot ember bed (oxidation zone) the tar and hydrocarbons are separated from the gas, resulting in a gas with very low tar.
Borealis Wood-Power Plant Overview
The plant consists of a gasification unit that processes wood chips to produce a wood gas and a CHP unit that generates electric and thermal power. Wood chip storage and handling facilities are required. The emissions are coal powder and exhaust gas that measure within acceptable emissions range of European laws. The plant operates on a carbon neutral basis. The residual ash is carbon and nitrogen that is used as fertilizer in Germany.
The generator is powered by a 5.7 l GM engine that produces 45 kW of electric power and 100 kW of thermal power for user consumption. The generator output is: 45 kW; 460 V; 60 Hz.
The current generator model requires hook up to the grid as external power is required for initial start-up. The 45 kW of power must either be fully utilized on-site or off-loaded onto the power grid. In many jurisdictions there are preferential rates for alternative biogas energy sold to the grid. It is often more advantageous to sell all the electrical output to the grid.
The wood chips should meet the following criteria to serve as optimum fuel for the generation of heat and electricity in a wood cogeneration plant:
- Wood chip size: 30mm – 40mm.
- Moisture content: max. 15 percent (water contents: approx. 13 percent).
- Fines: max. 30 percent (grain smaller than 3 - 4 mm).
- Easy flow material, i.e., with only a small percentage of longs.
20 unit installation
The system has proven it performs. With over 200 systems in field operation since 2009 with over one million hours of in service power production, shows how robust and reliable the technology is.
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