煤燃烧过程中氟析出特性与生成机理

通过建立的固定床管式炉煤燃烧氟析出试验装置，研究了煤燃烧过程中气态氟的排放特性，并根据燃煤氟析出等温动力学实验建立了气态氟生成动力学模型。结果表明：氟析出率随燃烧温度的升高而逐渐增加，煤中氟在300 ℃～400 ℃开始析出，500 ℃～1 100 ℃为主要析出温度范围；氟析出率随煤在炉内停留时间的增加而增加，但前5 min为主要析出阶段；炉内还原性气氛对氟析出有一定的影响；氟析出率与煤中氟赋存形态和含氟量有关。燃煤过程中氟析出过程可用一级反应动力学描述，反应活化能E和频率因子A依赖于煤中氟的赋存形态和氟化物的热稳定性。不同煤种E为28.0 kJ·mol－1～65.1 kJ·mol－1，A为12.5 min－1～46.0 min－1。

FLUORINE EMISSION CHARACTERISTICS AND KINETIC MECHANISM DURING COAL COMBUSTION

Vapor-phase fluorine emission characteristics during coal combustion have been studied by means of fixed bed tube furnaces. And the kinetics model of vapor-phase fluorine emission during coal combustion have been established successfully through the experimental data for constant temperature kinetics. The results indicated that fluorine emission tends to increase with increasing combustion temperature, fluorine emission starts at 300 ℃～400 ℃, 500 ℃～1 100 ℃ is the main fluorine emission temperature range. Fluorine emission increases with increasing retention period, the initial 5 min is the main fluorine emission period. Fluorine emission can be affected by reductive combustion atmosphere to some extent, and has relationship with mode of occurrence and content of fluorine in coal. Kinetics calculation has shown that fluorine emission during coal combustion can be described by first order reaction kinetics model, and activation energy and frequency factor depend on the mode of occurrence of fluorine and the thermal stability of fluorine-bearing minerals in coal. The activation energy is between 28.0kJ·mol－1 and 65.1 kJ·mol－1 and the frequency factor is between 12.5 min－1 and 46.0min－1 for experimental coals.