Stimulation effect of pulsed ultrasonic excitation on coal pores with full-scale pore sizes

Authors

LIN Haifei, College of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China; Key Laboratory of Western Mine Exploitation and Hazard Prevention, Ministry of Education, Xi’an 710054, ChinaFollow
QIU Yue, College of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
HAN Shuangze, College of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
GAO Haidong, Shaanxi Huangling No.2 Coal Mine Co., Ltd., Huangling 727307, China
YANG Erhao, College of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
WANG Ruizhe, College of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
YAN Min, College of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China; Key Laboratory of Western Mine Exploitation and Hazard Prevention, Ministry of Education, Xi’an 710054, China

Abstract

This study aims to further investigate the stimulation effect of pulsed ultrasonic excitation on coal pore structures. Using an ultrasonic excitation test system for gas-containing coals, this study conducted ultrasonic excitation tests on coals under continuous and interactive pulses with ultrasonic power of 800 W and 1000 W. Through low-pressure CO₂ adsorption tests, low-temperature nitrogen adsorption tests, and the mercury injection capillary pressure (MICP) tests, this study explored the evolutionary patterns of parameters of various coal pores with full-scale pore sizes, including macropores (> 50 nm), mesopores (2‒50 nm), and micropores (< 2 nm). The test results are as follows: (1) Pulsed ultrasonic waves can expand coal pores. The pore volume of coals was primarily provided by micropores and macropores, with mesopores representing a small proportion. The specific surface area of various coal pores was in the order of micropores > mesopores > macropores. (2) Compared with those having undergone continuous or no ultrasonic excitation, coal samples that experienced pulsed ultrasonic excitation exhibited increased pore volumes and specific surface areas of various core pores. (3) With an increase in the number of pulsed ultrasonic excitation, the increased amplitude of the pore volume and specific surface area of coal pores increased linearly. Most especially, macropores presented significantly high increased amplitude. Pulsed ultrasonic excitation caused the continuous transformation between the water hammer pressure stage and the stagnation pressure stage, which increased the level of damage to coal pore structures. Developing pulsed ultrasonic emitters, combined with hydraulic technology, can improve the developmental degree of coal pores, coal permeability, and gas drainage efficiency.

Keywords

pulsed ultrasonic wave, coal pore structure, stimulation effect, combination of pores with full-scale pore sizes

DOI

10.12363/issn.1001-1986.23.01.0033

Recommended Citation

LIN Haifei, QIU Yue, HAN Shuangze, et al. (2023) "Stimulation effect of pulsed ultrasonic excitation on coal pores with full-scale pore sizes," Coal Geology & Exploration: Vol. 51: Iss. 8, Article 16.
DOI: 10.12363/issn.1001-1986.23.01.0033
Available at: https://cge.researchcommons.org/journal/vol51/iss8/16

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