Influence of equivalence ratio of reduction zone on preheating combustion characteristics of pulverized coal [还原区当量比对煤粉预热燃烧特性的影响]

作者：Zhang Y.; Zhang J.; Zhu J.; Liu J.

来源：洁净煤技术, 2021, 27(6): 141-146.

DOI：10.13226/j.issn.1006-6772.20102102

• Equivalence ratio of reduction zone
• NOx
• Preheating combustion
• Pulverized coal

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 lest 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 oper?ating 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 in?creases, 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 ter-tian' air is fed,it is found that the nitrogen-containing gas mainly exists in the form of NO,. In the oxidizing zone of the downward combus?tion 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 (he 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 NO2 reduction is weakened, resulting in proportion in?crease of NO, rcduced to N,. The NO, concentration in the reduction zone is reduced. The ratio of NO2 being reduced to N2 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.

• 单位
  中国科学院大学