Full-scale co-firing of straw and coal

Co-firing of biofuels and coal in power plants is considered by the Danish utilities as a potential tool in reducing CO2 emissions. To test this, full-scale measurements were carried out for 1 week on a 250 MW(e) pulverized coal fired unit using 10-20% straw (thermal basis). With an increased ii action of straw in the fuel, a net decrease in NOx and SO2 emissions was measured. The SO2 emission decreased partly due to the lower sulfur content of the fuel per MJ, but also due to higher sulfur retention in the ash. The NO emission decreased solely due to lower conversion of fuel-N. An increased fraction of straw in the fuel blend resulted in a higher potassium content, but no significant increase in slagging or fouling was observed. Only small amounts of deposit at the lower part of the radiant superheater and little slagging at the furnace walls were observed as a result of co-firing straw and coal. No significant effects on the performance of the desulfurization plant were detected, which may be due to the short test period, probably not allowing the desulfurization process to reach steady-stale operation. Copyright (C) 1996 Elsevier Science Ltd.