LEI D J, ZHENG Y Y, MA T,et al.Adsorption model and mechanism of coal under high-strength electrical excitation[J].Journal of Henan Polytechnic University(Natural Science) ,2023,42(1):35-45.

doi:10.16186/j.cnki.1673-9787.2021070089

Received:2021/07/23

Revised:2021/10/08

Published:2023/01/25

Adsorption model and mechanism of coal under high-strength electrical excitation

LEI Dongji1,2, ZHENG Yuanyuan1, MA Tao1,3, WANG Yajuan1

1.State Key Laboratory Cultivation Base for Gas Geology and Gas Control，Henan Polytechnic University，Jiaozuo  454000，Henan，China；2.Coal Seam （Shale） Gas Collaborative Innovation Center of Henan Province，Jiaozuo  454000，Henan，China；3.Shenhua Shendong Coal Group Co.，Ltd.，Shenmu  719300，Shaanxi，China

Abstract:Based on the electric effect，thermal effect and induced polarization effect of coal response under electric field strengthening，a coal adsorption test system under high strength electric field was designed and constructed.The adsorption characteristics of coal to different adsorbates under real-time electric field loading were studied experimentally，and the coal adsorption model suitable for electric field was constructed based on the classical Langmuir and D-R adsorption models.The results showed that，under real-time loading of high-strength electric field，with the increase of electric field intensity，the adsorption capacity of coal decreases linearly，and the change rate of carbon dioxide adsorption capacity affected by electric field was larger.When the electric field intensity was 30，60 and 90 kV/m，the adsorption capacity of coal to methane decreased by 10.9%，15.7% and 18.9%，while the adsorption capacity of carbon dioxide decreased by 8.5%，12.1% and 22.9%.Based on the Langmuir adsorption model and D-R adsorption equation and the experimental data of coal adsorption，a modified coefficient (1-C·E) with electric field intensity was introduced into the coal adsorption model，the coal adsorption model with electrical parameters was constructed.The experimental fitting degree of the new model was above 0.99，which could predict and characterize the adsorption characteristics of coal under electric field.The mechanism of coal modification by high strength electric strengthening was mainly summarized as follows：The pore structure of coal was changed.After electric field strengthening，the micropores of coal samples transited to small pores and medium and large pores，which increased the diffusion performance of coal.It affected the surface free energy of coal adsorbing gas，and Gibbs free energy decreased with the increase of electric field strength，which revealed that the electric field inhibitted the adsorption of coal to gas molecules.Excited polarization occurred in coal，and the electric field could change the physical properties such as dielectric constant and resistivity of coal electrical parameters，and then act on the adsorption and diffusion ability of gas.

Key words:high strength electric field;adsorption model;power up in real-time;mechanism analysis

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