Combustion property improvement of poorly combustible coal by co-firing of agglomerates consisting of biomass-calcium carbonate and coals (I): Co-firing characteristics in circulating fluidized bed combustion of poorly combustible coals

Binder less briquette of Coal Combustion Improver (CCI), which consists of pulverized coal and the same quantity of lime cake or paper sludge on dry basis, has been developed to improve combustibility of bituminous coal. Co-firing characteristics of the CCI was studied by bench-scale circulating fluidized bed combustion furnace at 850 °C under the blending ratio of 90% of bituminous coal with 10% of crushed CCI. The results showed that the CCI improved the combustibility of the coal and fly ash properties, and decreased emission of air pollutants. It was explained on the mechanism that fast pyrolysis of the CCI leads to decompose the CCI into the various size of particles, which is the compounds of coal and lime cake or paper sludge, and then the particles easily burn and interact each other in very short time in the combustion zone.