瘦煤热破裂规律显微CT试验

Micro-CT experimental research of lean coal thermal cracking laws

由太原理工大学和中国工程物理研究院应用电子学研究所共同研制的μCT225kvFCB型高精度(μm级)CT试验分析系统,对7mm瘦煤从18℃到600℃高温下的热破裂过程进行了显微观测和分析,发现瘦煤在100℃时有微裂隙出现;200℃时煤样中裂隙长度增加了30%左右;当温度达到300℃时煤样中有大量裂隙和孔隙产生并贯通,热破裂阈值在300℃附近;400℃到500℃时裂隙进一步扩展连通产生裂隙带;600℃时煤样中裂隙长度减小,同时产生了很多新的裂隙和孔隙;随温度的升高,7mm瘦煤的裂隙发展规律为:微裂纹的出现、发展、贯通,最后裂纹继续发展;煤样的最大裂隙长度具有随着温度的升高先减小后增加最后减小的规律;煤样的孔裂隙率从常温到500℃具有先降低后增加再降低到600℃达到最大的特点。

Utilizing the μCT225kVFCB micro-CT experimental system（μm grade）,which was newly co-designed by Taiyuan University of Technology and Applied Electronics Institute,Academy of Engineering Physics of China,a series of triaxial microscopic observation and analysis of lean coal thermal cracking under temperatures from 18℃ to 600℃ were carried out.At 100℃,it is observed that a small quantity of micro-fissures.At 200℃,the length of fractures in coal increases by 30%.When the temperature reaches 300℃,there are a lot of coal produced and through cracks.It is demonstrated that the thermal cracking temperature threshold is 300℃ for the lean coal.The maximum length of coal fracture first decreases and then increases the final reduces with increasing temperature.From 18℃ to 500℃ the porosity first decreases and then increases.The porosity is maximum at 600℃.