BlackCarbon unit (BC300)
The BlackCarbon unit at Barritskov in Denmark is a CHP unit that converts biomass into biochar through pyrolysis, releasing bioenergy in the process.
The BlackCarbon unit is a pyrolysis-based CHP unit with a Stirling engine. It converts fuel equivalent to 250 kW; of this, 35kW is electricity, 110 kW district heated water and 110 kW biochar. The wood chips are fed into the unit and heated by pyrolysis. The gases produced from the pyrolysis process are combusted separately to create heat and electricity. The carbon-rich biochar residue is then extracted from the unit.
Pyrolysis is the controlled heating for decomposition of organic substances with little or no oxygen, which allows for the capture of syn-gases for electricity and heat and the creation of biochar as a byproduct.
The heat exchanger preheats air for the combustion of syn-gas in the CHP burner and converts excess heat into hot water, taking the exhaust gases from 500 degrees C to 150 degrees C.
CHP stands for combined heat and power and is also known as cogeneration. It is a term used to describe the simultaneous production of heat and electricity by one source.
A Stirling engine is a closed cycle external combustion engine that needs little maintenance, is noted for its high efficiency and quiet operation and the ease with which it can utilize almost any heat source. The fluctuating temperature causes the pistons to move up as the hot helium gas expands, then the pistons move back down again as the cooled down gas contracts, allowing the pistons to run an external electric generator, which produces electricity.
ENERGY AND MASS BALANCE