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Two concepts for a combined combustion of biomass with hard coal

Conference ·
OSTI ID:458548
; ; ; ;  [1]
  1. Univ. of Stuttgart (Germany). Inst. fuer Verfahrenstechnik und Dampfkesselwesen
A blending of pulverized biomass with coal showed a high burnout up to 20% thermal input of biomass for all particle sizes of the biofuels tested. CO-emissions were generally lower than 150 mg/m{sup 3} and remain below 100 mg/m{sup 3} in most cases. Reburn investigations with three pulverized biomasses resulted in NOx-emissions of about 300 mg/m{sup 3} at 6% O{sub 2} (approx. 150 ppm). Beside co-combustion of coal/biomass mixture, it also seems attractive to run a combined fired boiler (coal and biomass) using biomass in a pre-gasification of pre-pyrolysis to produce a gas that can be applied as an additional fuel in a secondary firing zone of the combustion unit. This technology promises advantages in NOx-emission control. Detailed studies have been carried out to lower NOx-emissions in coal fired boilers using pyrolysis gas as reburn fuel. A research project has been initiated together with an industrial partner. The results point out that the high German emission standards of 200 mg/m{sup 3} at 6% O{sub 2} (approx. 100 ppm/m{sup 3}) can be achieved at the test facility without SCR using pyrolysis gas from coal and biomass as reductive. Because of using a gaseous reburn fuel, there are no problems with burnout or CO-emissions. Beside high reburn efficiency, a pre-pyrolysis of biomass in a divided process of co-combustion results in separated ashes of both fuels (biomass and coal), which may have a positive influence on slagging and boiler corrosion and the further application of the ashes.
Sponsoring Organization:
Commission of the European Communities, Brussels (Belgium)
OSTI ID:
458548
Report Number(s):
CONF-960322--; ISBN 0-932066-21-6
Country of Publication:
United States
Language:
English