Influence of Two-Stage Air Injection Conditions on NO_x and Unburned Carbon of Sub-Bituminous Coal Combustion(<Special Issue>International Conferences on Power and Energy System)

Because of large recoverable reserves, sub-bituminous coal is an important energy resources. The disadvantage of sub-bituminous coal is that it contains more than 20% moisture. This makes ignition less efficient. And combustion flame became diffused. Both emissions of NO_x and unburned carbon in fly ash become high. We have already shown that these emissions can be reduced by adjusting the air injection conditions from the burner to better suit sub-bituminous coal combustion. However, the reduction is insufficient compared with bituminous coal combustion. In this investigation, influence of two-stage air injection conditions on NO_x and unburned carbon concentration in fly ash was studied and the optimum air injection conditions necessary in order to reduce those emissions were clarified.