34. Experimental Study of NO_x Emission and Char Characteristics

The NOx emission and char characteristics during coal combustion process in a one-dimension furnace for different air ratios were studied combined with BET, SEM and FTIR analysis. Nitrogen-containing organic compounds in the rapid pyrolysis products of char were determined by pyrolysis chromatography/mass spectrometry (Py-GC/MS). The results obtained shown that when air ratios in the main combustion zone decreased from 0.85 to 0.65, the exit NOx concentration decreased from 315 to 125 ppm. The variation trends of the oxygenic functional group content were contrary to the NOx. The Py-GC/MS experimental results showed that the benzonitrile (BN) released in large amounts from char taken in the primary 400 mm distance. The char specific surface areas (SSA) changed with the coal volatile matters releasing and char burning process along the furnace. With the progress of coal combustion, the numbers of surface micropore first increased and then decreased, following that the macropores appeared, and finally most pores collapsed and chars broke into small particles.