ZHANG Yi;ZHANG Jiahang;ZHU Jianguo;LIU Jingzhang;

• 1:Institute of Engineering Thermophysics
• 2:Chinese Academy of Sciences
• 3:University of Chinese Academy of Sciences

Abstract：

Preheating combustion is a new technology of high temperature preheating modification of pulverized coal and re-combustion of preheated fuel. Based on the 30 kW pulverized coal preheating combustion test apparatus, the influence of the change of the equivalence ratio in the reduction zone on the preheating combustion characteristics of the pulverized coal was researched by basically keeping the operating parameters of the circulating fluidized bed equivalence ratio, preheating temperature, and excess air coefficient unchanged. The results show that the main combustion zone of the downward combustion chamber moves toward the top nozzle, the temperature near the nozzle increases, and the temperature along the downward combustion chamber decreases with the increase of the distance from the nozzle when the equivalence ratio of the reduction zone increases. From the nozzle of the downward combustion chamber to the reducing zone where the tertiary air is fed, it is found that the nitrogen-containing gas mainly exists in the form of NO_2. In the oxidizing zone of the downward combustion chamber after the tertiary air being fed, the nitrogen-containing gas mainly exists in the form of NO. The increase of the equivalence ratio of the reduction zone reduces the CO concentration in the reduction zone of the downward combustion chamber, that is, the reducing atmosphere is weakened. The inhibition effect of low concentration of CO content on NO_2 reduction is weakened, resulting in proportion increase of NO_2 reduced to N_2. The NO_2 concentration in the reduction zone is reduced. The ratio of NO_2 being reduced to N_2 increases. The NO concentration in the oxidizing atmosphere also decreases with the increase of the air equivalence ratio in the reduction zone. It indicates that the form of nitrogen-containing gas in the preheated fuel combustion is closely related to the combustion chamber atmosphere. The generated NO and CO concentrations are both low when the reduction zone equivalence ratio is 0.96.

Key Words： preheating combustion;pulverized coal;equivalence ratio of reduction zone;NO_x

Abstract:

Keywords:

Foundation: 国家重点研发计划资助项目(2018YFB0604201)

Authors: ZHANG Yi;ZHANG Jiahang;ZHU Jianguo;LIU Jingzhang;

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