CO-COMBUSTION OF KOREAN ANTHRACITE WITH VARIOUS FUELS IN A COMMERCIAL CIRCULATING FLUIDIZED BED BOILER

The effect of co-combustion of various fuels such as bituminous coal, imported anthracite, RDF and wood pellet with Korean anthracite on the combustion and environmental performance was observed in the commercial CFB boiler. The temperatures in the furnace and cyclones exits decreased with increasing the cocombustion ratio of the bituminous coal, which could achieve more stable operation of the CFB boiler. During Co-combustion of the RDF and wood pellets, the temperature of the furnace exit increased slightly with due to volatiles re-combustion which could restrict to increase the co-combustion ratio of the RDF and wood pellets in the CFB boiler. It was limited for the electrostatic precipitator (EP) to maintain the stable operation above 5% of the RDF co-combustion ratio according to decrease of the output voltages of the EP collecting plate. High content of CaO in the RDF and the wood pellet made the required limestone flow rates decrease. The emissions NOx, HCl and dioxin during co-combustion of the RDF and wood pellets did not change appreciably when compared with firing only Korean anthracite, which were also low enough to meet Korean regulation limits. On the other hand, chlorine content in the ashes emitted from the boiler increased gradually with increasing the RDF co-combustion ratio because of absorption by limestone. The co-combustion of various fuels with Korean anthracite in the commercial CFB boiler was found to be of great use up to a certain co-combustion ratio of each fuel without the technical and environmental problems