Influence law of power plant flue gas injection pressure on desorption efficiency of adsorbed state gas in coal beds

doi:10.16265/j.cnki.issn1003-3033.2025.05.1581

Abstract

Abstract:

In order to explore the effect of gas injection pressure of power plant on the adsorption gas desorption efficiency of coal seam, NMR technology was used to quantitatively study the dynamic change process of CH₄ competitive adsorption under different gas injection pressure of power plant. The influence law of gas injection pressure on methane desorption, desorption efficiency and unit time recovery efficiency was obtained. The experimental results show that when anthracite coal adsorbs CH₄, the T₂ spectrum shows a bimodal characteristic. As time increases, the peak of T₂ spectrum of adsorbed CH₄ increases, while the peak of T₂ spectrum of free CH₄ decreases. With the increase of time, the adsorption rate of CH₄ by coal slows down. During the competitive adsorption process of power plant flue gas and CH₄ from coal, the T₂ spectrum exhibits three-peaks characteristics. As time progresses, the T₂ spectrum peaks of adsorbed CH₄ decreases, while the T₂ spectrum peaks of free CH₄ increases. The integrals of adsorbed and free T₂ spectra show an exponential function with the adsorption time, and a linear function with the pressure of flue gas injection in the power plant. The power plant flue gas injection pressure shows a linear increase with CH₄ desorption efficiency. The injection of 3.5 MPa power plant flue gas increases the total desorption of adsorbed CH₄ from coal samples in the sample tank by 0.016 mol, enhances the recovery efficiency per unit time by 3.440%, and increases the total desorption efficiency by 20.631%, compared to 1.5 MPa.

Key words: power plant flue gas, injection pressure, adsorbed gas, desorption efficiency, nuclear magnetic resonance(NMR), competitive adsorption

CLC Number:

X936

BAI Gang, ZHANG Haijing, SU Jun, LIANG Han, ZHANG Xiaowen, LIU Zhengdong. Influence law of power plant flue gas injection pressure on desorption efficiency of adsorbed state gas in coal beds[J]. China Safety Science Journal, 2025, 35(5): 91-98.

Figures/Tables 8

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References 24

[1]	刘峻麟. 低渗煤层CO₂-ECBM过程气体吸附解吸-扩散-渗流特征及煤岩物性响应机理[D]. 淮南: 安徽理工大学, 2023.
	LIU Junlin. Characteristics of gas adsorption-desorption-diffusion-seepage and response mechanism of petrophysical properties in low permeability coal during CO₂-ECBM process[D]. Huainan: Anhui University of Science and Technology, 2023.
[2]	LIU He, LI Zhenbao, WANG Hu, et al. Numerical simulation investigation of N₂ injection for enhanced coalbed methane recovery[J]. Arabian Journal for Science and Engineering, 2024: DOI: 10.1007/s13369-024-09123-1.
[3]	ZHANG Hongyang, DIAO Rui, MOSTOFI M, et al. Molecular simulation of enhanced CH₄ recovery and CO₂ storage by CO₂-N₂ mixture injection in deformable organic micropores[J]. Journal of Natural Gas Science and Engineering, 2020, 84: DOI: 10.1016/j.jngse.2020.103658.
[4]	金智新, 武司苑, 邓存宝, 等. 不同浓度烟气在煤中的竞争吸附行为及机理[J]. 煤炭学报, 2017, 42(5): 1201-1206.
	JIN Zhixin, WU Siyuan, DENG Cunbao, et al. Competitive adsorption behavior and mechanism of different flue gas proportions in coal[J]. Journal of China Coal Society, 2017, 42(5): 1201-1206.
[5]	MAZUMDER S, VAN HEMERT P, BUSCH A, et al. Flue gas and pure CO₂ sorption properties of coal: a comparative study[J]. International Journal of Coal Geology, 2006, 67(4): 267-279.
[6]	赵宇新. 离柳矿区煤对电厂烟气吸附特性试验研究[J]. 同煤科技, 2022(3): 29-33,36.
[7]	高飞, 邓存宝, 王雪峰, 等. 电厂烟气注入采空区封存的可行性[J]. 环境科学研究, 2016, 29(7): 1096-1100.
	GAO Fei, DENG Cunbao, WANG Xuefeng, et al. Feasibility analysis on seal of power plant smoke injected in to the goaf[J]. Research of Environmental Sciences, 2016, 29(7): 1096-1100.
[8]	WU Siyuan, JIN Zhixin, DENG Cunbao. Molecular simulation of coal-fired plant flue gas competitive adsorption and diffusion on coal[J]. Fuel, 2019, 239: 87-96. doi: 10.1016/j.fuel.2018.11.011
[9]	WU Siyuan, DENG Cunbao, WANG Xuefeng. Molecular simulation of flue gas and CH₄ competitive adsorption in dry and wet coal[J]. Journal of Natural Gas Science and Engineering, 2019, 71:DOI: 10.1016/j.jngse.2019.102980.
[10]	李成兵. N₂/CO₂/H₂O抑制甲烷爆炸化学动力学机理分析[J]. 中国安全科学学报, 2010, 20(8): 88-92.
	LI Chengbing. Chemical kinetic mechanism analysis of N₂/CO₂/H₂O suppressing methane explosion[J]. China Safety Science Journal, 2010, 20(8): 88-92.
[11]	HASSANPOURYOUZBAND A, YANG Jinhai, OKWANANKE A, et al. An experimental investigation on the kinetics of integrated methane recovery and CO₂ sequestration by injection of flue gas into permafrost methane hydrate reservoirs[J]. Scie.pngic Reports, 2019, 9(1): DOI: 10.1038/s41598-019-52745-x.
[12]	MU Yongliang, FAN Yongpeng, WANG Jiren, et al. Numerical study on injection of flue gas as a heat carrier into coal reservoir to enhance CBM recovery[J]. Journal of Natural Gas Science and Engineering, 2019, 72: DOI: 10.1016/j.jngse.2019.103017.
[13]	杨宏民, 梁龙辉, 冯朝阳, 等. 注气压力对不同注源气体置驱效应的影响[J]. 中国安全科学学报, 2017, 27(9): 122-128. doi: 10.16265/j.cnki.issn1003-3033.2017.09.021
	YANG Hongmin, LIANG Longhui, FENG Zhaoyang, et al. Study on influence of injection pressure on replacement effect for different injection gases[J]. China Safety Science Journal, 2017, 27(9): 122-128. doi: 10.16265/j.cnki.issn1003-3033.2017.09.021
[14]	ZHAO Guang, WANG Chen. Influence of CO₂ on the adsorption of CH₄ on shale using low-field nuclear magnetic resonance technique[J]. Fuel, 2019, 238: 51-58. doi: 10.1016/j.fuel.2018.10.092
[15]	翟成, 孙勇, 范宜仁, 等. 低场核磁共振技术在煤孔隙结构精准表征中的应用与展望[J]. 煤炭学报, 2022, 47(2): 828-848.
	ZHAI Cheng, SUN Yong, FAN Yiren, et al. Application and prospect of low-field nuclear magnetic resonance technology in accurate characterization of coal pore structure[J]. Journal of China Coal Society, 2022, 47(2): 828-848.
[16]	韩光, 李东芳, 常利强, 等. 基于核磁共振技术不同煤样吸附CH₄实验研究[J]. 中国安全生产科学技术, 2021, 17(1): 143-148.
	HAN Guang, LI Dongfang, CHANG Liqiang, et al. Experimental research on CH₄ adsorption of different coal samples based on NMR technology[J]. Journal of Safety Science and Technology, 2021, 17(1): 143-148.
[17]	罗明坤, 李胜, 荣海, 等. CH₄与N₂, CO₂间竞争吸附关系的核磁共振实验研究[J]. 煤炭学报, 2018, 43(2): 490-497.
	LUO Mingkun, LI Sheng, RONG Hai, et al. Experimental study on competitive adsorption relationship between CH₄ and N₂, CO₂ by NMR[J]. Journal of China Coal Society, 2018, 43(2): 490-497.
[18]	YAO Yanbin, LIU Dameng, XIE Songbin. Quantitative characterization of methane adsorption on coal using a low-field NMR relaxation method[J]. International Journal of Coal Geology, 2014, 131: 32-40.
[19]	ZHOU Guangzhao, DUAN Xianggang, ZHANG Jin, et al. Investigation of CH₄/CO₂ competitive adsorption-desorption mechanisms for enhanced shale gas production and carbon sequestration using nuclear magnetic resonance[J]. Energy, 2023, 278: DOI: 10.1016/j.energy.2023.127964.
[20]	ZHAO Yu, WANG Chaolin, LIN Ning, et al. Pore and fracture development in coal under stress conditions based on nuclear magnetic resonance and fractal theory[J]. Fuel, 2022, 309: DOI: 10.1016/j.fuel.2021.122112.
[21]	SUN Xiaoxiao, YAO Yanbin, LIU Dameng, et al. Interactions and exchange of CO₂ and H₂O in coals: an investigation by low-field NMR relaxation[J]. Scie.pngic Reports, 2016, 6(1):DOI: 10.1038/srep19919.
[22]	LI Xiangchen, KANG Yili, HAGHIGHI M. Investigation of pore size distributions of coals with different structures by nuclear magnetic resonance (NMR) and mercury intrusion porosimetry (MIP)[J]. Measurement, 2018, 116: 122-128.
[23]	杨明, 柳磊, 张学博, 等. 不同阶煤孔隙结构与流体特性的核磁共振试验研究[J]. 中国安全科学学报, 2021, 31(1): 81-88. doi: 10.16265/j.cnki.issn 1003-3033.2020.01.012
	YANG Ming, LIU Lei, ZHANG Xuebo, et al. Nuclear magnetic resonance experimental study on pore structureand fluid characteristics of coal at different ranks[J]. China Safety Science Journal, 2021, 31(1): 81-88. doi: 10.16265/j.cnki.issn 1003-3033.2020.01.012
[24]	BAI Gang, ZHOU Zhongjie, LI Xueming, et al. Quantitative analysis of carbon dioxide replacement of adsorbed methane in different coal ranks using low-field NMR technique[J]. Fuel, 2022, 326: DOI: 10.1016/j. fuel. 2022.124980.