Abstract
High Temperature Air Combustion Technology (HiCOT) is a promising technology for the reduction of pollutant gas and improvement of combustion efficiency. This technology has been developed for industrial furnaces using gaseous fuel, and plenty of industrial furnaces in Japan have employed HiCOT in order to save fuel consumption and to reduce NOx emission. In this paper, HiCOT has been adopted to pulverized coal combustion which has been widely used in coal fired boilers. The effect of air temperature on ignition and NOx formation behavior is investigated using 30kg/h pulverized coal furnace. From the experiment, it is revealed that ignition delay is decreased by high temperature air and a stable flame can be formed even for high fuel ratio coal. This is due to the enhancement of volatile release from the coal. Also, fuel-NOx is reduced by increasing the air temperature. From the measurement of volatile and nitrogen release along the furnace, it is revealed that fuel-N is released in a strong reduction zone near the burner, and the rate of NOx formation reaction is decreased. Low-NOx behavior is also confirmed using 150kg/h pulverized coal furnace.
