Experimental investigations of the conversion of fuel-N, volatile-N and char-N to NOx and N2O during single coal particle fluidized bed combustion

Abstract: In this work, the attention is focused on the conversion of fuel-N, volatile-N and char-N to NOx and N 2 O of two types of coal (anthracite with low volatile content and bituminous with relatively high volatile content) in fluidized bed combustion. The experiments are carried out in a single particle combustion test rig, the mass reduction of burning coal particle, NOx and N 2 O formation in the flue gas are measured. The influence of temperature (1043, 1103, 1163 K) on the conversion of fuel-N, volatile-N and char-N to NOx and N 2 O is also investigated. The experimental results show that about 70% – 80% of all the NOx produced is formed from char-N for both two types of coal, while 20% – 30% of all the NOx produced is formed from volatile-N. About 45% of all the N 2 O produced is formed from volatile-N for anthracite, and for bituminous more than 70% of all the N 2 O produced is formed from volatile-N. With the combustion temperature of 1043 K, the conversion of char-N to NOx is more than 80% for anthracite, while the conversion of volatile-N to NOx is only 36% for anthracite. For bituminous, the conversion of char-N and volatile-N to NOx is both about 45%. About 5% of the volatile-N yields N 2 O, and 4% of char-N yields N 2 O for anthracite, while more than 12% of the volatile-N yields N 2 O and only 2% of char-N yields N 2 O for bituminous. The temperature produces little influence on the conversion of fuel-N, volatile-N and char-N to NOx for anthracite. For bituminous, the conversion of fuel-N, volatile-N and char-N to NOx increases with the increased temperature. However, the conversion of fuel-N, volatile-N and char-N to N 2 O decreases when the combustion temperature increases for both two types of coal. These results are favorable for industrial control and the understanding of the formation mechanism of NOx and N 2 O.