EFFECT OF IRON AND CALCIUM COMPOUNDS ON NO EMISSION DURING COAL COMBUSTION Results and Discussion

Emission profiles of NO and CO. During coal combustion, carbon was firstly oxidized to form CO which was further oxidized to CO2. The total concentration of CO and CO2 represented the rate of coal oxidation. We did not measure the CO2 for the limitation of the Gas Analyzer, hence the exact rate of coal combustion could not be known, but we could gain a general idea by analyzing the concentration of O2 and CO. Figure 1 shows the emission profiles of NO, CO and O2. It was clearly seen that there were a major peak of O2 reduction at nearly 6000C and a shoulder peak at about 4500C. The shoulder peak resulted from the combustion of volatile, and the main peak was due to the combustion of char. The peak temperature for CO formation is at around 5000C, which is mainly due to the oxidation of volatile matters. After that, with rising the temperature the oxidation of CO accelerated, at the same time the oxidation of char to form CO became difficult because of the bad reactivity of char compare to that of volatile matters, the CO concentration was decreased and formed a shoulder peak at about 5500C