煤在气化通道中气化反应效率是影响煤炭地下气化气体组分与热值的关键问题。为揭示反应温度和压力对三塘湖盆地褐煤在水蒸气中气化行为和产物分布特征影响,基于固定床热解炉对三塘湖盆地西山窑组褐煤进行不同反应温度和压力热解试验。结果表明:随反应温度升高(300~900℃),气体质量分数由3.84%增至24.29%,水和焦油质量分数先增后减;高温下反应温度升高,加剧二次反应,H2和CH4体积显著增加,900℃体积最大分别为100.89、106.09mL/g,污染物总质量减少,900℃质量分数相对小,17.72mg/g。增加反应压力(1.5~3.0MPa),利于提高半焦转化率和增加气体质量分数。高温下反应压力增加,加剧二次反应,利于反应加氢气化和甲烷化发生,导致CH4体积显著增加,700℃CH4体积最多增加26.89mL/g,但在700℃会促进自由基加氢饱和反应,污染物总质量增加。建议在实际生产中,通过控制注汽移动速度适当增加反应温度并提高反应压力,且控制气化反应区的温度远离700℃,利于H2和CH4生成,以提高煤炭地下气化工艺高效清洁开发。研究成果可为三塘湖盆地西山窑组褐煤煤炭地下气化工艺提供指导。

The gasification reaction efficiency of coal in the gasification channel is a key issue affecting the gas composition and calorificvalue of underground coal gasification. To reveal the effects of reaction temperature and pressure on the gasification behavior and productdistribution characteristics of lignite in water vapor using the coal deposited in the Santanghu Basin, pyrolysis experiments were carried outusing lignite collected from the Xishanyao Formation of the Santanghu Basin based on a fixed-bed pyrolysis furnace under different reactiontemperatures and pressures. With the increase of reaction temperature (300-900 ℃ ), the gas mass fraction increased from 3.84% to24.29%, and the mass fractions of water and tar increased first and then decreased. The volume of H2 and CH4 increased significantly withthe increase of reaction temperature, with the maximum volume of 100.89 and 106.09 mL/ g at 900 ℃ , respectively. The total mass of pollutants decreases, and the mass is relatively small at 900 ℃ , 17.72 mg/ g. Increasing the reaction pressure (1.5-3.0 MPa) is beneficialto improve the conversion of semi-coke and increase the gas mass fraction. The increase of reaction pressure aggravates the secondary reaction, which is conducive to the occurrence of hydrogasification reaction and methanation reaction, resulting in a significant increase in thevolume of CH4. At 700 ℃ , the volume of CH4 increases by up to 26.89 mL/ g. However at 700 ℃ , the free radical hydrogenation saturation reaction is promoted, resulting in an increase in the total mass of pollutants. It is suggested that in the actual production, the reactiontemperature and pressure should be increased by controlling the moving speed of steam injection, and the temperature of gasification reaction zone should be controlled away from 700 ℃ ,which is beneficial to the formation of H2 and CH4, so as to improve the efficiencyand clean development of underground coal gasification process. The research results can provide guidance for the underground coal gasification process of lignite in Xishanyao Formation of the Santanghu Basin.

0 引言

1 地质背景

2 试验

   2.1 试验样品

   2.2 试验流程

   2.3 气体组成分析及其热值计算方法

   2.4 焦油组成分析

3 反应温度对褐煤水蒸气氛围下热解影响

   3.1 热解产物产率

   3.2 气体产物组成

   3.3 气体热值组成特征

   3.4 焦油产物组成

   3.5 工艺建议

4 反应压力对褐煤水蒸气氛围下热解影响

   4.1 热解产物产率

   4.2 气体产物组成

   4.3 气体热值组成特征

   4.4 焦油产物组成

   4.5 工艺建议

5 水蒸气氛围对褐煤热解影响机理

   5.1 反应温度影响机理

   5.2 反应压力影响机理

6 结论