@article{oai:muroran-it.repo.nii.ac.jp:00009241,
 author = {SU, Faqiang and 蘇, 発強 and 板倉,  賢一 and ITAKURA, Ken-ichi and DEGUCHI, Gota and 出口, 剛太 and OHGA, Kotaro and 大賀, 光太郎},
 journal = {Applied Energy},
 month = {Mar},
 note = {application/pdf, During the underground coal gasification (UCG) process, fracturing and cracks occur
 inside the gasification zone and surrounding rocks as the underground coal cavity evolves.
Although fracturing activity and crack extension directly affect gasification efficiency and
 have environmental impacts, little research to date has focused on their effects. This study
 discusses the application of acoustic emission (AE) analysis for the evaluation of distinctly
 designed UCG models and operational parameters and describes the gasification process
 based on its results. We studied the cavity growth, fracturing mechanism, and the effects of
 various design and operational variables, such as linking-hole type, gas feed rate, and
 gasification agent. We found that the AE activity was closely related to the temperature
 change occurring inside the coal, with AE generation apparently resulting from crack
 initiation and extension around the coal gasification area, which occurs as a result of
 thermal stress. UCG modeling showed that the location of AE sources reflects the size of
 the gasification area and the cavity growth. In addition, the quantitative information on the
 located AE sources can be obtained. The introduction of a process control system into
 UCG modeling along with AE monitoring allowed for the real-time monitoring of the
 fracturing and cavity evolution inside a combustion reactor. Together, these processes have
 the potential to significantly reduce field risk in UCG by enabling the timely adjustment of
 operational parameters. Thus, AE monitoring is useful for maintaining a safe and efficient
 UCG process.},
 pages = {142--156},
 title = {Monitoring of coal fracturing in underground coal gasification by acoustic emission techniques},
 volume = {189},
 year = {2017},
 yomi = {イタクラ, ケンイチ and デグチ, ゴウタ and オオガ, コウタロウ}
}