Effect of the Primary Air Velocity on Ignition Characteristics of Bias Pulverized Coal Jets

Experiments were conducted under a hot condition of bituminous coal ignition in a 250 kW pilot-scale bias combustion simulator. The effects of the primary air velocity (PAV) on the ignition characteristics of bias pulverized coal jets in a reducing atmosphere were investigated to develop a better new burner for experimental bituminous coal. Multiple means of measurement and sampling were used for the axial and radial temperatures, flame spectrum, flue gas components, and residual solid inside the furnace. The standoff distance changed nonmonotonically between axial distances of 90 and 330 mm with increasing PAV and was shortest for a PAV of 16 m/s. The radiation heat transfer from the hot environment had more effect on the ignition than the convection heat transfer from high-temperature flue gas in the initial stage, while the convection heat transfer from the high-temperature flue gas played a greater role in the subsequent combustion of the char. At PAVs of 13 and 16 m/s, there was volatile and char hom...