Using high-voltage electrical pulses to crush coal in an air environment: An experimental study

An experimental system was developed to study the feasibility of crushing coal using high-voltage electrical pulses in an air environment to increase the permeability of coalbed methane (CBM) reservoir. Anthracite coal samples from Linhua and Guhanshan coal mine were chosen and analyzed in this study. It is indicated that the breakdown field strength of air is 18-183 kV/cm, whereas these of the Linhua and Guhanshan coal samples are 1.6-1.7 kV/cm and 1.2-1.4 kV/cm, respectively. The breakdown field strength of the coal sample was far less than that of air. The response of the coal sample to electrical breakage was random and varied from one coal sample to another, and coal sample mainly presented three types of damage. It was also found that the number of coal pieces formed during crushing by high-voltage electrical pulses will increase with increases in breakdown voltage. Results of microscopic analysis indicated that the number of pores and fractures formed on coal was increased by high-voltage electrical pulses, which subsequently increased the permeability of CBM reservoirs. Our experimental results suggest that applying high-voltage electrical pulses is a promising technology to increase the CBM output. (C) 2016 Elsevier B.V. All rights reserved.