Effect of coal quality on the optimum fuel concentration in high-concentration pulverized coal flame

High-concentration pulverized coal flame plays an important role of ignition for coal combustion system with rich-lean burners. In the presented works, a series of tests have been performed in a 1 MW tangentially pulverized coal-fired furnace with rich-lean burners and in a simplified down-fired furnace to investigate the relation between the coal quality and the optimum fuel concentration (kg/kg), which is corresponding to the highest flame temperature and the lowest content of unburned carbon. The results show that there is always an optimum fuel concentration corresponding to the highest furnace temperature and the shortest ignition length for each group of tests on the high-concentration pulverized coal flame, and the optimum fuel concentration generally decreases with the product of volatile content and heating value linearly as the empirical formula C_opt = 1.069-0.051·10^-5·V·Q.