Effect of microwave irradiation on petrophysical characterization of coals

• Published in: Applied thermal engineering 2016-06, Vol.102, p.1109-1125
• Main Authors: Hong, Yi-du, Lin, Bai-quan, Zhu, Chuan-jie, Li, He
• Format: Article
• Language: English
• Subjects: CBM; Coal; Microwave heating; NMR; Porosity; Temperature
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2016.04.019

•Microwave energy increase porosity, pore size and numbers of coals.•Growth rates of porosity decreased at first then increased with microwave energy.•NMR can be reliable to measure coal samples.•Microwave energy may have the potential for degassing of coal seams. The experimental work described in this paper aims to study the effect of microwave irradiation on petrophysical characterization of coals. Twenty coal samples were irradiated at 2.45GHz with variable power (2, 4, 6kW). The temperature, mass and specific heat capacity of coal samples were measured and calculated. The effect of microwave irradiation on the porosity of coal samples was evaluated by the gravimetric method and nuclear magnetic resonance (NMR) measurements. The porosity obviously increases after microwave heating. Interestingly, growth rate of the porosity decreases at first then increases with microwave energy. The turning point is approximately 100kJ. The influence of microwave irradiation on pore size, throat size and pore numbers of coal samples were also evaluated by NMR measurements. It suggest that the pore size, throat size and pore numbers are obviously increase with microwave energy. In a word, it appears likely that microwave energy may have the potential for the degassing coal seams.