The Investigation of NOx Formation and Reduction during O2/CO2 Combustion of Raw Coal and Coal Char

Abstract

Abstract This study investigated the behavior of NO x emissions during combustion of pulverized coal char and pulverized raw coal in O 2 /CO 2 environments under nearly isothermal condition in a drop tube furnace. A representative Chinese coal Ling Nancang (LNC) and LNC CO 2 -char (made in CO 2 condition) were studied with four different excess oxygen ratios (α=0.6, 0.8, 1.2, and 1.4). Combustion experiments were performed with an elevated concentration (850 ppm) of NO. When α increased from 0.6 to 1.4, the total amount of NOx reduction was increased in both pulverized coal and char combustion. To investigate the effects of coal and char on NO x reburn reactions, LNC coal char and the raw coal combustion experiments were also performed under three high background NO concentrations (400, 850, and 1200 ppm) in O 2 /CO 2 atmosphere. During experiments with elevated NO concentrations, there was an increase in net NO reduction; however, there was also a decrease in the calculated NO reduction ratio.