School of Energy Science and Engineering, Henan Polytechnic University
Key Laboratory of Green Building in Western China, Xi’an University of Science and Technology
State Key Laboratory for GeoMechannics and Deep Underground Engineering

在煤炭地下气化过程中，高温产生的热应力会导致煤体不断破裂，可能会导致气体泄漏，因此煤体破裂的实时监测与规律研究对煤炭地下气化系统长期稳定运行具有重要意义。为此，采用声发射(AE)监测手段对不同气化通道类型的模型实验(带底部交叉孔的垂直同轴气化通道、垂直同轴气化通道、V形连接孔气化通道)中的煤体破裂活动进行了监测，并基于监测结果研究了不同操作参数(气化剂组分和流量)以及气化通道类型对煤体破坏活动及气化区扩展的影响，然后采用矩张量分析构建的裂纹分布模型定量分析了气化过程中声发射源处的裂纹类型以及裂纹方向，从而研究煤在气化过程中的损伤和破坏规律。研究结果表明：气化炉整体温度变化与声发射事件有非常强的相关性，在0～750 ℃内增加会导致声发射事件增多；实验中定位的声发射源可以较为准确的表示煤体破裂位置，通过对声发射源整体分布的监测可以预测气化区的扩展范围，垂直同轴孔模型气化区主要向两侧扩展，而V形连接孔模型的气化区则主要沿气流流动方向扩展；较高的氧体积分数以及气体流量在温度小于氧化区临界温度(900 ℃)时能显著地促进气化区的扩展；基于矩张量分析构建的裂纹分布模型能有效帮助研究煤炭地下气化过程中煤体的破裂规律，裂纹分布模型结果显示，拉伸破坏主导气化过程中煤体的破坏，裂纹总体的聚集方向接近煤层的分层方向，此外裂纹位置分布结果表明在还原区范围内裂纹的萌生与扩展活动较为活跃。

During the underground coal gasification process, the thermal stress produced at high temperatures will lead to coal cracking, which may cause gas leakage. Therefore, a real-time monitoring and regularity research of coal cracking is of significance for the long-term and stable operation of underground coal gasification systems. Acoustic emission (AE) technology is used to monitor coal fracturing activity in experimental models of different gasification channel types (coaxial gasification channel, coaxial gasification channel with bottom cross-hole, and V-type connection hole gasification channel). Based on the monitoring results, the influences of different operating parameters (gasification agent components and flow rates) and gasification channel types on coal fracturing activity and gasification area expansion are studied. Then, the crack distribution model constructed by moment tensor analysis is used to quantitatively analyze the crack position, type, and direction at the source of the AE during gasification, so as to study and predict the damage and destruction of coal during gasification. The study results show that: there is a strong correlation between the actual temperature change in the gasifier and the AE events, and an increase in temperature in the range of 0−750 ℃ will lead to an increase in the AE events. The located AE sources in the experiment can accurately represent the position of coal fractures, and the expansion range of the gasification area can be predicted by monitoring the overall distribution of the AE sources. The gasification area of the coaxial hole model mainly expands to both sides, while the gasification area of the V-shaped connecting hole model mainly expands along the direction of airflow. Higher oxygen concentration and gas flow at temperatures below the critical oxidation zone temperature (900 ℃) significantly promote the expansion of the gasification zone. The crack distribution model based on the moment tensor analysis can effectively help to study the fracture law of coal during underground coal gasification. The results of crack distribution model show that the tensile failure dominates the destruction of the coal mass during gasification. The overall direction of crack aggregation is close to the stratification direction of the coal seam. In addition, the results of crack location distribution show that the crack initiation and propagation activities are active in the reduction zone.

中国矿业大学深部岩土力学与地下工程国家重点实验室开放基金资助项目(SKLGDUEK2004)；河南省重点研发与推广专项(科技攻关)资助项目(222102320139)；河南省高等学校重点科研计划资助项目(22B440003)

苏发强，邓启超，武俊博，等. 基于不同气化通道类型的地下气化煤体破裂监测及扩展规律[J]. 煤炭学报，2023，48(10)：3845−3858.

SU Faqiang，DENG Qichao，WU Junbo，et al. Study on fracturing monitoring and expansion law of underground gasification coal based on different gasification channel types[J]. Journal of China Coal Society，2023，48(10)：3845−3858.