Mechanism of AE Generation in Underground Coal Gasification for Utilization of Low-Grade Coal

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14575
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 31020:Earth resource engineering, Energy sciences-related
• Research Institution: Kyushu University
• Principal Investigator: Hamanaka Akihiro 九州大学, 工学研究院, 助教 (20758601)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 石炭地下ガス化 / UCG / AE計測 / 低品位炭 / 水素

Outline of Final Research Achievements

The results of a study on AE generation during the gasification reaction of low-grade coals in underground coal gasification revealed that a large amount of AE is generated in non-caking low-grade coals. It was also found that AE was generated more frequently during gas generation including water vapor. Small-scale UCG model experiments also confirmed the formation of a high-temperature region in low-grade coals, which promotes gasification reactions similar to those in high-grade coals. In addition, the reaction zone was expanded in the low-grade coals with numerous AE events and crack generation. Therefore, it is clear that the high-temperature area necessary for gasification can be formed in low-grade coals as well as high-grade coals. Besides, the reaction zone tends to expand more easily in low-grade coals than in high-grade coals due to their non-coking feature.

Free Research Field

岩盤工学、地圏開発システム工学

Academic Significance and Societal Importance of the Research Achievements

石炭を加熱した場合に発生するAEに関しては学術的文献が限られているが、本研究により石炭の温度変化に伴うAE発生には粘結性の有無やガスの発生が関係していることが明らかとなり、高温環境下での破壊メカニズムに関して新たな知見を得ることができた。また、石炭の埋蔵量の多くは褐炭や亜瀝青炭などの低品位炭に分類されるが、それらの低品位炭はUCGにおいて反応領域が広範囲に拡大するため、エネルギー回収という観点から有利に働くことが明らかとなり、未利用資源の有効活用に関する可能性を示すことができた。