(91b) Flame Stability with Oxy-Coal Combustion

Coal combustion is responsible for roughly one-third of the CO2 emissions in the United States. Reducing CO2 from conventional coal-fired power plants via carbon capture and sequestration could be very costly due to the low concentration of CO2 in the flue gas. One approach to increase the relative CO2 concentration in the exhaust is to remove the nitrogen from the oxidizer and introduce CO2 rich exhaust gases to control temperature. This strategy has been termed exhaust gas recirculation or oxy-combustion. In this study the effects of oxy-combustion on flame stability is investigated utilizing a Type I pulverized coal flame in a down-fired 0.5 to 35 kW thermal laboratory scale coal combustor.

Experimentally, flame stability was characterized by the primary oxidizer Reynolds number at flame blow-off. Several flames were investigated at various molar oxygen, nitrogen, and carbon dioxide concentrations in the non-swirl Primary Oxidizer (PO) and tangentially induced swirl Secondary Oxidizer (SO). Experimental results showed increased stability with increased equivalence ratio and increased oxygen concentrations in the PO and SO.