Estimation of gasification area of underground coal gasification by using acoustic emission monitoring

Akihiro Hamanaka, Ken ichi Itakura, Fa qiang Su, Gota Deguchi, Jun ichi Kodama

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Underground coal gasification (UCG) is a process of producing combustible gases by the in-situ conversion of coal into gaseous products. Coal resources abandoned under the ground for either technical or economic reasons can be recovered with economically and less environmental impacts by UCG; therefore, this technology is regarded as a clean coal technology. UCG has several advantages of low investments, high efficiency, and high benefits compared to conventional coal gasification. However, some environmental risks such as gas leakage, surface subsidence, and underground water pollution are difficult to control because the process is invisible. The reactor in UCG is unstable and expands continuously due to fracturing activity caused by coal combustion. It is, therefore, considered that acoustic emission (AE) is an effective tool to monitor the fracturing activities and visualize the inner part of coal. For this study, UCG model experiments were conducted using coal blocks of 0.55 × 0.60 × 2.74 m to discuss the applicability of AE monitoring for the estimation of the crack generations during UCG process and the extent of the gasification area. Temperatures were also monitored because the crack generations were strongly related to thermal stress occurred by coal combustion and heat transfer. The monitoring results of AE agreed with the measured data of temperatures and the gasification area; the source location of AE was detected around the region temperature increased and the gasification area. Additionally, the gasified coal amount can be predicted by using the data of product gas. Therefore, AE monitoring combined with the prediction of reacted coal amount are expected to be a useful tool as monitoring system of the gasifier in the underground.

Original languageEnglish
Title of host publicationISRM International Symposium - 10th Asian Rock Mechanics Symposium, ARMS 2018
PublisherInternational Society for Rock Mechanics
ISBN (Electronic)9789811190032
Publication statusPublished - Jan 1 2018
Event10th Asian Rock Mechanics Symposium, ARMS 2018 - Singapore, Singapore
Duration: Oct 29 2018Nov 3 2018

Publication series

NameISRM International Symposium - 10th Asian Rock Mechanics Symposium, ARMS 2018

Conference

Conference10th Asian Rock Mechanics Symposium, ARMS 2018
CountrySingapore
CitySingapore
Period10/29/1811/3/18

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All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics

Cite this

Hamanaka, A., Itakura, K. I., Su, F. Q., Deguchi, G., & Kodama, J. I. (2018). Estimation of gasification area of underground coal gasification by using acoustic emission monitoring. In ISRM International Symposium - 10th Asian Rock Mechanics Symposium, ARMS 2018 (ISRM International Symposium - 10th Asian Rock Mechanics Symposium, ARMS 2018). International Society for Rock Mechanics.