摘要
To investigate the micro-pores development of coal under high temperature, experimental studies were performed with fine specimen of lean coal as small as 1 mm in diameter through a micro-CT system μCT225kVFCB. Through statistic analysis,some fundamental characteristics of pores development are discovered with temperature rising from 18 ℃ to 600 ℃. It was demonstrated that the thermal cracking temperature threshold is 300 ℃ for lean coal. From room temperature to 300 ℃ the porosity of coal increased by 0.5 times. Fractal analysis demonstrates that,most of the original regular small pores become connected and gradually grow to irregular and larger pores as the effect of thermal expansion and cracking with temperature rising. Above 400 ℃, the size of the pores becomes smaller again while the pore number increases with the complicated effect of pyrolysis of the coal.