褐煤热破裂的显微CT实验

采用μCT225kVFCB型高精度显微CT试验系统并配以微型气氛炉，研究了内蒙古平庄褐煤热破裂随温度的变化关系。研究结果表明，褐煤在100 ℃左右时，大裂隙(>800 μm)占主导地位；200 ℃左右时，中等裂隙（100~400 μm）占主导地位；300 ℃之后微裂隙（<100 μm）占主导地位；热破裂的阈值为300 ℃左右；在300 ℃之前孔隙裂隙的产生发展主要是因为热破裂，300 ℃之后，微裂隙和孔隙的产生主要是因为煤体发生热解化学反应，油气逸出，固体骨架逐渐转变为半焦体。

Micro-CT experimental of the thermal cracking of brown coal

Using μCT225kVFCB high precision micro CT system and a small moveable argon furnace,thermal cracking of brown coal from Pingzhuang mining in Inner Mongolia municipality was studied under different temperature.The results show that for brown coal,the big cracks(>800 μm) occupy leading position at about 100 ℃,the medium cracks(100~400 μm) are more important than others at about 200 ℃,the micro cracks（<100 μm）become dominant above 300 ℃;threshold temperature of thermal cracking is 300 ℃,more or less;when temperature is lower than 300 ℃,the formation and evolution of crack and pore result mostly from thermal cracking,above 300 ℃,micro cracks and pores produce mainly because coal pyrolysis produce and release oil gas,and turn coal skeleton into char gradually with temperature.