Monitoring the gasification area and its behavior in underground coal gasification by acoustic emission technique instead of temperature measurement

Abstract

Underground Coal Gasification (UCG) requires monitoring of the gasification area because the gasification process is invisible and the reaction temperature exceeds 1000 °C. Many fracturing events that occurred due to coal heating can be captured with Acoustic Emission (AE) monitoring technique during UCG. However, the temperature conditions to generate fracturing events during UCG have not yet been clarified. Therefore, the coal heating experiment and small-scale UCG experiment are conducted by measuring the temperature and AE activities in this research to examine the applicability of the AE technique instead of temperature measurement as a monitoring method during UCG. As a result, many fracturing events are generated when the temperature of coal is changed drastically, especially during coal gasification. Besides, AE events increase in the sensor near the heat source and AE sources are expanded widely with the expansion of the high-temperature region. AE monitoring is an effective technique for the estimation of the gasification area during UCG instead of temperature monitoring.

Increasing the underground coal gasification efficiency using preliminary electromagnetic coal mass heating

“…One of the promising technologies for the coal industry development is underground coal gasification technology, which can be an important step in preserving and optimizing the coal industry, providing a more sustainable and environmentally friendly way of using this important energy resource. Underground coal gasification (UCG) is a method of extracting coal energy from underground by in-situ gasification [30], [31]. Gasification is a chemical process for converting a solid or liquid fuel into a combustible gas.…”

Simulation of Underground Coal-Gasification Process Using Aspen Plus

“…According to the BP World Energy Statistical Yearbook released on 26 June 2023 [2], in 2022, China's primary energy consumption amounted to 159.39 × 10 18 J, with coal representing 55.5% of the consumption, followed by oil at 17.7%, nuclear power, hydropower, and renewable energy at 18.4%, and natural gas only accounting for 8.5%, with over 40% of natural gas still relying on imports. While underground coal gasification has been experimented with and studied for nearly a century, only Australia's Linc Energy has successfully established a commercial underground coal-gasification plant in Uzbekistan, with a daily production capacity of 1 × 10 6 m 3 /d [3,4]. China currently has more than ten experimental projects, though they still have a long way to go before industrialization can be achieved.…”