A numerical model of coal blending for boilers burning lean coal is established. Different coal blending schemes for a 330 MW unit boiler are calculated to analyze the key parameters influencing the char burnout ratio in low NOx combustion mode. The simulation results show that

the feeding height of lean coal has a significant impact on the burnout ratio. When two layers of meagre coal are burned with the other four layers of bituminous coal

the burnout ratio at the furnace outlet reduces from 98.9% to 98.2% as the height of lean coal layer increases.The burnout ratio decreases from 99.1% to 97.2% as the number of lean coal layer increases from 1 to 5

the burnout ratio decreases as the number of blended layer increases. When the number of blended layers of small-particle lean coal increases from 0 to 5

the char burnout ratio increases from 97.6% to 99.2%. However

the char burnout ratio can reach 98.9% when only the upper two layers of primary air nozzle are fed with small particle size lean coal. The coal blending numerical model can be used to simulate the in-furnace coal blending process. The quantitative data of furnace temperature distribution and fly ash carbon content can be obtained to provide guidance for determining the optimum coal blending strategy.