NOx and H2S formation in the reductive zone of air-staged combustion of pulverized blended coals

• 作 者: Jinzhi CAI Dan LI Denggao CHEN Zhenshan LI
• 机 构: Key Laboratory for Thermal Sciece and Power Engineering of the Ministry of Education,Department of E
• 出 处: 能源前沿
• 发表日期: 2021年1期
• 关键词: blended coal combustion NOx formation H2S formation air staged combustion

Low NOx combustion of blended coals is widely used in coal-fired boilers in China to control NOx emission;thus,it is necessary to understand the formation mechanism of NOx and H2S during the combustion of blended coals.This paper focused on the investigation of reductive gases in the formation of NOx and H2S in the reductive zone of blended coals during combustion.Experiments with Zhundong(ZD)and Commercial(GE)coal and their blends with different mixing ratios were conducted in a drop tube furnace at 1200℃-1400℃with an excessive air ratio of 0.6-1.2.The coal conversion and formation characteristics of CO,H2S,and NOx in the fuel-rich zone were carefully studied under different experi-mental conditions for different blend ratios.Blending ZD into GE was found to increase not only the coal conversion but also the concentrations of CO and H2S as NO reduction accelerated.Both the CO and H2S concentrations inblended coal combustion increase with an increase in the combustion temperature and a decrease in the excessive air ratio.Based on accumulated experimental data,one interesting finding was that NO and H2S from blended coal combustion were almost directly dependent on the CO concentration,and the CO concentration of the blended coal combustion depended on the single char gasification conversion.Thus,CO,NOx,and H2S forma-tion characteristics from blended coal combustion can be well predicted by single char gasification kinetics.