Study on gas desorption characteristic of coal core during the frozen coring

Shujun  Ma; Zhaofeng  Wang; Liguo  Wang; Haidong  Chen; Qiao  Wang; Xin  Guo

doi:10.6180/jase.202509_28(9).0015

Study on gas desorption characteristic of coal core during the frozen coring

Environmental Engineering Water Resources Engineering

Shujun Ma¹This email address is being protected from spambots. You need JavaScript enabled to view it., Zhaofeng Wang¹, Liguo Wang¹, Haidong Chen², Qiao Wang², and Xin Guo²

¹School of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, China

²School of Resource & Environment and Safety Engineering, Hunan University of Science and Technology, Xiangtan 411201, China

Received: September 11, 2024
Accepted: November 18, 2024
Publication Date: December 28, 2024

Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.6180/jase.202509_28(9).0015

Coal seam gas content is the basic parameter of coal gas disaster control, the main cause of gas content measured distortion is due to gas fast desorption and large gas loss. Based on the cognition of gas desorption rate decreasing with temperature lowering, the frozen coring for restraining gas desorption was put forward, which is created to realize the accurate prediction of gas content. Frozen coring was different from conventional coring, due to the refrigeration effect of cryogen, coal was maintained in the low-temperature environment in coring process, which can inhibit the gas desorption. To reveal the gas desorption characteristic of coal during the frozen coring, the frozen coring simulation test device was used to conduct frozen coring gas desorption simulation experiments at different gas pressures. The results showed that the gas desorption during the frozen coring showed the segmented characteristic of rapid desorption in the initial stage, stop desorption in the middle stage, and slow desorption in the late stage. The higher the gas pressure, the greater the initial desorption amount and rate, and the longer the duration. The initial desorption rate and duration at 2.0 MPa pressure was almost twice as long as at 0.5 MPa pressure. In the middle stage of freezing, the higher gas pressure, the shorter duration, and the earlier it entered next desorption stage. The mid-term duration was 78.2% longer at 0.5 MPa than at 2.0 MPa , and the time to the next stage was 41.4% earlier at 2.0 MPa than at 0.5 MPa. The variation curve of gas desorption in the late stage of freezing can be described by the modified Langmuir equation. The desorption rate first increased and then decreased, and the higher gas pressure, the greater increased range. Within the experimental pressure range, the gas diffusion coefficient increased with the increased of gas pressure, and the gas diffusion coefficient at 2.0 MPa was 1.64 times that of 0.5 MPa . The research results provide theoretical basis for predicting gas loss in frozen coring process under different coal seam gas pressures.

Keywords: Frozen coring; Low temperature; Gas content; Simulation test; Gas desorption

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