褐煤热破裂的显微CT实验

Micro-CT experimental of the thermal cracking of brown coal

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（〉800μm）占主导地位;200℃左右时,中等裂隙（100~400μm）占主导地位;300℃之后微裂隙（〈100μm）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。

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.