Experimental studies on the effect of the pulverized coal concentration on lean-coal combustion in a lateral-ignition tiny-oil burner

Because of the low volatile content and high ignition temperature of lean coal, it is difficult to employ tiny-oil ignition technology in the firing up and partial-load operation of a pulverized-coal-fired boiler. To investigate the influence of the coal concentration on lean-coal combustion in a lateral-ignition tiny-oil burner, full-scale reacting-flow experiments were performed using an experimental setup. As the coal concentration increased from 0.27 to 0.80 kg (corresponding to a coal feed rate increasing from 1.5 to 4.5 tons/h), the gas temperatures at the burner center line and 116.5 mm from the burner center line (10 mm from the burner wall) decreased gradually at equivalent measuring points. The gas temperatures on the side with oil guns were higher than those on the opposite side for the same distances from the burner exit. O₂ concentrations at the exit of the burner were 0.41-3.64%. The burner resistance resulting from the flow and combustion of pulverized coal was 1400-2200 Pa. Increasing the coal concentration decreased coal burnout and the release rates of C and H at equivalent points at the burner exit.