Study on the law of coal resistivity variation in the process of gas adsorption/desorption

Abstract In order to detect coal and gas outburst disasters by means of electric exploration technology, the characteristics of gas adsorption/desorption electrical response were studied. The law of resistivity variation of different coal samples was investigated under different gas pressures with the aid of a self-built real-time test system of coal resistivity during gas adsorption/desorption. In addition, the mechanism of coal resistivity variation was studied. The research results indicate that coal resistivity decreases during gas adsorption and increases during gas desorption, but generally it cannot return to the initial value. Gas influences coal resistivity through a variety of mechanisms. In the gas adsorption process, coal resistivity decreases under the combined effect of surface energy decline, skeleton expansion, free gas pressure and adsorption swelling stress. In addition, as the gas pressure rises, the resistivity varies in a wider range. The coal resistivity shares the relation of y = a + b ln(x + c) with gas pressure and the relation of y = ax + b with the content of adsorbed gas. This study lays a foundation for the application of electrical prospecting technology to gas hazard prediction and provides technical support for safe production in coal mines.

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Experimental research on desorption characteristics of gas-bearing coal subjected to mechanical vibration

Energy Exploration & Exploitation ◽

10.1177/0144598720956286 ◽

2020 ◽

Vol 38 (5) ◽

pp. 1454-1466

Author(s):

Xuexi Chen ◽

Liang Zhang ◽

Maoliang Shen

Keyword(s):

Coalbed Methane ◽

Gas Adsorption ◽

Mechanical Vibration ◽

Particle Diameter ◽

Reference Value ◽

Desorption Rate ◽

Gas Desorption ◽

Adsorbed Gas ◽

Vibration Parameters ◽

Adsorption Desorption

Mechanical vibration can induce coal and gas outburst accidents, and can also promote the exploitation of coalbed methane. In this paper, a vibration-adsorption-desorption experiment system was established, the effects of coal sample particle diameter, gas pressure, and vibration frequency on gas desorption were studied. Mechanical vibration can generate a shear force in the adsorbed gas and promote gas desorption, but there are appropriate vibration parameters. Within the range of experimental parameters, the larger the amplitude, the more favorable for gas desorption. The change rules of gas desorption rate and desorption quantity under different conditions are basically the same, showing a power function shape with time increase, and most of the desorption quantity was completed within the first 5 minutes. The gas desorption rate and desorption quantity were positively related to the gas adsorption pressure. The results have great reference value for preventing gas outbursts and promoting gas exploitation.

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Experimental Study on Gas Pressure Effects on Gas Desorption Characteristic of Coal Seam

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.318.367 ◽

2013 ◽

Vol 318 ◽

pp. 367-370 ◽

Cited By ~ 2

Author(s):

Lin Chao Dai ◽

Da Yong Lu ◽

Zhen Liu

Keyword(s):

Coal Seam ◽

Gas Adsorption ◽

Experimental System ◽

Gas Pressure ◽

Pressure Effects ◽

Gas Content ◽

Equilibrium Pressure ◽

Gas Desorption ◽

Exploitation And Utilization ◽

The Impact

To further explore the impact of gas pressure on gas desorption and flowing law, the gas desorption experimental system designed autonomously is used to carry out studies on gas desorption experiment under different gas pressures. By data fitting, the relationship between gas desorption quantity and time is obtained and also established the model for gas desorption. The results show that: the gas desorption quantity curves is "The first half rises sharply, the latter half segment is gently rising and eventually becomes stabilized", and when the gas adsorption equilibrium pressure is the greater, the gas desorption amount is greater. And the formula can describe the gas desorption law well, the correlation coefficient R2 is above 0.97. The study provides an important theory reference to coal and gas outburst prediction, coal seam gas content prediction and its exploitation and utilization.

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Analysis of Antireflection and Outburst Prevention Mechanism on Hydrofracture Technology in Soft Coal Seam

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.556-562.597 ◽

2014 ◽

Vol 556-562 ◽

pp. 597-602

Author(s):

Yi Lei ◽

Wen Bin Wu

Keyword(s):

Mechanical Properties ◽

Coal Seam ◽

Gas Adsorption ◽

Coal Extraction ◽

Phase Flow ◽

Two Phase ◽

Soft Coal ◽

Gas Desorption ◽

Soft Coal Seam ◽

Adsorption Desorption

Base on the hydraulic fracturing field test in soft coal seam, the rule which the cutting quantity is added and the drilling gas desorption index K1 is decreased, is analyzed from the perspective of physical-mechanical properties and adsorption-desorption law is changed, etc. And gas adsorption and desorption law was analyzed using the theory of two-phase flow, to determine the effect after fracturing coal extraction is improved and the main reason for reducing the outburst.

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Experimental Study of the Characteristic Changes of Coal Resistivity during the Gas Adsorption/Desorption Process

Advances in Materials Science and Engineering ◽

10.1155/2018/1450187 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7 ◽

Cited By ~ 2

Author(s):

Zengchao Feng ◽

Chen Wang ◽

Dong Dong ◽

Dong Zhao ◽

Dong Zhou

Keyword(s):

Gas Adsorption ◽

Gas Content ◽

Resistivity Change ◽

Adsorption Experiment ◽

Desorption Process ◽

Continuous Adsorption ◽

Gas Desorption ◽

Original Figure ◽

Adsorption Desorption ◽

The Relationship

To study the influence of gas adsorption-desorption on the resistivity of coal, the resistivity changes in conditions of continuous adsorption/desorption and isovolumetric adsorption/desorption were tested by high-precision resistance measurement, and the relationship between coal resistivity and gas content was investigated. The results show that gas adsorption/desorption has obvious effects on the resistivity of coal. Similar behavior was observed both in continuous adsorption/desorption and in isovolumetric adsorption/desorption experiments. The coal resistivity decreased gradually at the very beginning and then tended to stabilize as the gas adsorption capacity increased; in the process of gas desorption, the resistivity demonstrated a linear relationship with gas content. When comparing resistivities for the different adsorption modes, it was found that, for the same gas content in each mode, the resistivity change in the isovolumetric adsorption experiment was more obvious than in the continuous adsorption experiment. Also, the coal resistivity in the isovolumetric experiment differed further from the original figure when the desorption ended. The results are significant for predicting gas content in the coal mining process.

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Laser THz Emission Spectroscopy of Gas Adsorption-Desorption Dynamics in Tungsten Disulfide Nanosheets

e-Journal of Surface Science and Nanotechnology ◽

10.1380/ejssnt.2016.78 ◽

2016 ◽

Vol 14 (0) ◽

pp. 78-82 ◽

Cited By ~ 1

Author(s):

Filchito Renee Bagsican ◽

Iwao Kawayama ◽

Hironaru Murakami ◽

Masayoshi Tonouchi ◽

Andrew Winchester ◽

...

Keyword(s):

Emission Spectroscopy ◽

Gas Adsorption ◽

Tungsten Disulfide ◽

Adsorption Desorption

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HCl gas adsorption/desorption properties of poly(N-isopropylacrylamide) brushes grafted onto quartz resonator for gas-sensing applications

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2014.10.137 ◽

2015 ◽

Vol 208 ◽

pp. 106-111 ◽

Cited By ~ 14

Author(s):

Masanobu Matsuguchi ◽

Kenta Takaoka ◽

Haruka Kai

Keyword(s):

Gas Adsorption ◽

Gas Sensing ◽

Quartz Resonator ◽

Sensing Applications ◽

Hcl Gas ◽

Adsorption Desorption

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A Reduced Fuel Cell Stack Model for Control and Fault Diagnosis

Journal of Fuel Cell Science and Technology ◽

10.1115/1.2349517 ◽

2006 ◽

Vol 3 (4) ◽

pp. 384-388 ◽

Cited By ~ 7

Author(s):

Damiano Di Penta ◽

Karim Bencherif ◽

Michel Sorine ◽

Qinghua Zhang

Keyword(s):

Fuel Cell ◽

Fault Diagnosis ◽

Gas Adsorption ◽

Carbon Monoxide Poisoning ◽

Important Indicator ◽

Fuel Cell Stack ◽

Electrode Potentials ◽

The Difference ◽

Adsorption Desorption ◽

Stack Model

This paper proposes a reduced fuel cell stack model for control and fault diagnosis which was validated with experimental data. Firstly, the electro-chemical phenomena are modeled based on a mechanism of gas adsorption/desorption on catalysts at the anode and at the cathode of the stack, including activation, diffusion, and carbon monoxide poisoning. The electrical voltage of a stack cell is then modeled by the difference between the two electrode potentials. A simplified thermal model of the fuel cell stack is also developed in order to take into account heat generation from reactions, heat transfers, and evaporation/condensation of water. Finally, the efficiency ratio is computed as a model output. It is used to evaluate the efficiency changes of the entire system, providing an important indicator for fault detection.

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