Abstract: In order to apply semi-coke to large-proportion co-combustion in pulverized coal boilers and reduce NOx
emission，the study on devolatilization and nitrogen conversion characteristics of bituminous coal and semi-coke blends
under different mixing proportions are made on a dropping tube furnace. The results show that under certain temperature，
the release rate of volatile matters is related to the mixing proportion and the residence time in the furnace. The release rate
of volatile matters decreases as the mixing proportion of semi-coke increases，and accumulates with the increase of the
residence time. The maximum release rate of volatile matters is greater than that in proximate analysis. And with the
increase of the blending proportion of semi-coke，the char nitrogen from the blend shows an upward trend，and the volatile
nitrogen shows a downward trend. When the proportion of semi-coke exceeds 50% of the blend，the char nitrogen of the
blend increases by 6.08% compared with that of the raw coal，thus the difficulty of NOx emission control increases.

Key words: semi-coke, bituminous coke, blending, devolatilization, volatile nitrogen, char nitrogen, NOx emission