Effect of initial temperature and H2 addition on explosion characteristics of H2-poor/CH4/air mixtures

Li, Ruikang; Luo, Zhenmin; Wang, Tao; Cheng, Fangming; Lin, Haifei; Zhu, Xiaochun

doi:10.1016/j.energy.2020.118979

Cited by 50 publications

(13 citation statements)

References 67 publications

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“…This part of the heat that is consumed due to external reasons such as the heat exchange on the wall of the container is also called the heat loss during the explosion process . Quantitative research and analysis can deepen the understanding of the explosion process and can provide a theoretical basis for the development of appropriate protective measures. − Since the explosion reaction is an extremely fast process, we only consider the surface heat loss in the process of calculating the explosion heat loss, while ignoring the volumetric radiative heat loss, which is also ignored in most previous studies. , Then, the heat loss per unit area in the closed container (referred to as the explosion heat loss) during the explosion process is where Q rel is the total energy released by the explosion of the mixed gas, J; Q acc is the energy acting on the explosion overpressure and explosion temperature, J; Q tra is the energy loss caused by the heat exchange between the mixed system and the container, J; m is the amount of mixed gas; C e,v is the average heat capacity of the burned gas; T max,ad is the theoretical adiabatic combustion temperature, K; T max,real is the actual peak combustion temperature, K; P max,ad is the theoretical adiabatic combustion overpressure peak, kPa; P max,real is the actual explosion overpressure peak value, kPa; γ e is the adiabatic index of the burned gas ( C P / C V ); V is the volume of the airtight container, m 3 ; S is the inner surface area of the airtight container, m 2 ; and q tra is the internal heat loss per unit area of the airtight container during the explosion process, J/m 2 .…”

Section: Resultsmentioning

confidence: 99%

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Experimental Study of the Influence of H₂/CO on the CH₄ Explosion Pressure and Thermal Behaviors

Zhang¹,

Zhou²,

Yang³

et al. 2022

ACS Omega

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In a spontaneous coal combustion environment and in the coal chemical process, multiple gases, such as CH 4 , H 2 , and CO, coexist, and explosion accidents are prone to occur. The causes of these disasters and the explosion characteristics are key to formulating preventive measures. To explore the effect of H 2 /CO on the explosion pressure and thermal behavior of methane–air, CH 4 with initial volume fractions of 7, 9.5, and 12%, which correspond to three states of oxygen enrichment, equivalence ratio, and oxygen depletion, was selected. Moreover, a mixed fuel system is composed of H 2 /CO with different volume ratios. A 20 L spherical gas explosion experimental system was used to test the peak explosion overpressure P max , the maximum explosion overpressure rise rate (d P /d t )max, and the corresponding time parameters of the H 2 /CO–CH 4 mixed system. Combined with the thermodynamic calculation model, laminar burning velocity S L , explosion heat loss q tra , and other parameters were obtained. The results show that due to the existence of the damping effect, CO has the dual characteristic of promoting or weakening methane explosions. Compared with CO, the effect of H 2 on the methane explosion is more significant, and the improvement or weakening of the laminar combustion rate of the reaction system by CO “lags” behind that of H 2 . The heat loss in the process of a gas explosion is affected by factors such as the heat release rate, the propagation speed of the combustion wave, and the heat dissipation effect of the container wall. When H 2 /CO increases the laminar burning velocity of the mixed system, the heat loss decreases accordingly. This study also found that the laminar burning velocity model of the mixed gas based on the ideal spherical flame propagation theory is not fully applicable to the H 2 /CO/CH 4 mixed system in a spherical closed space, and the calculation results have large errors when the mixed system is close to the upper limit of the explosion.

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Section: Resultsmentioning

confidence: 99%

“…The results show that the increased initial pressure or turbulence level greatly enhances the flame propagation instability for oxygen-lean CH 4 –H 2 mixtures. 28 …”

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Influence of H₂/CO on the CH₄ Explosion Pressure and Thermal Behaviors

Zhang¹,

Zhou²,

Yang³

et al. 2022

ACS Omega

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“…Studies on the spontaneous combustion of coal have shown that the action of functional groups of varying nature present in the molecular structure of coal is a fundamental factor in the oxidative warming and hence spontaneous combustion of coal [39]. In this experiment, the changes in the functional groups of the selected test coal samples at different temperatures were investigated and analysed.…”

Section: Effect Of Highly Efficient Water Retaining Colloidal Materials On Functional Groups In Coalmentioning

confidence: 99%

Research on the Damping Performance of Mining Highly Efficient Water-Retaining Colloidal Material Against the Spontaneous Combustion of Coal

Jin¹,

Li²,

Liu³

et al. 2021

ACSM

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In order to solve the shortcomings of the traditional mining anti-extinguishing gel material such as low strength and poor water retention, a high hydrocolloid anti-extinguishing material was developed with sodium alginate and light calcium carbonate as the base material and gluconolactone as the retarder, which was mixed and reacted. The base material ratio of highly efficient water-retaining colloidal material for coal void filling was determined as 2% SA + 0.5% PCC + 1% GDL with a moulding time of 4.5 min, while the base material ratio of highly efficient water-retaining colloidal material for extinguishing high temperature fires was 2.5% SA + 1% PCC + 1% GDL with a moulding time of 2.5 min. The highly efficient water-retaining colloidal material was found to reduce the concentration of signature gas and delay the characteristic temperature point and increase the activation energy of coal oxidation, which indicates that the highly efficient water-retaining colloidal material can effectively inhibit the spontaneous combustion process of coal at low temperature stage. Infrared spectroscopy experiments were conducted to investigate the microscopic resistance mechanism of the highly efficient water-retaining colloidal material, and the results showed that the highly efficient water-retaining colloidal material mainly reduce the activity of Ar-C-O-, -COO-, -CH3, -CH2 and -OH in coal to inhibit the spontaneous combustion of coal.

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“…According to coal mine safety regulations, a coal seam requires pre‐draining to lower the gas pressure and gas content to safe values of 0.74 MPa and 8 m 3 /t, respectively, before mining 4 . Otherwise, a gas outburst or even a gas explosion can occur due to the presence of excessive gas in the coal working face 5,6 . Mine gas primarily contains methane (CH 4 ), which poses a hazard to the atmosphere; given that it has an ozone depletion potential and a greenhouse effect that are 7‐ and 25‐fold higher than that of carbon dioxide (CO 2 ), respectively, 7,8 even though it is a clean and efficient energy source.…”

Section: Introductionmentioning

confidence: 99%

“…4 Otherwise, a gas outburst or even a gas explosion can occur due to the presence of excessive gas in the coal working face. 5,6 Mine gas primarily contains methane (CH 4 ), which poses a hazard to the atmosphere; given that it has an ozone depletion potential and a greenhouse effect that are 7-and 25-fold higher than that of carbon dioxide (CO 2 ), respectively, 7,8 even though it is a clean and efficient energy source. According to the 13th five-year plan for the Development and Utilization of Coalbed Methane, CBM extraction was expected to reach 24 × 10 9 m 3 by 2020.…”

Section: Introductionmentioning

confidence: 99%

Liquid CO ₂ high‐pressure fracturing of coal seams and gas extraction engineering tests using crossing holes: A case study of Panji Coal Mine No. 3, Huainan, China

et al. 2020

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Summary Owing to the low coal permeability coefficients and poor gas extraction efficiencies associated with the extraction of coal in the Huainan coal mining area, the aim of this study was to design, for the first time, a high‐pressure low‐temperature liquid CO2 (LCO2) pump for engineering tests with respect to the fracturing of coal seams and the improvement of CH4 recovery in China. To reasonably calculate the initiation pressure for the coal seam fracturing as well as the gas flow parameters, theoretical analysis with field testing were integrated in the design. In addition, considering the interim gas extraction standard, the gas extraction equivalent radius based on this standard was calculated. The test results revealed a maximum LCO2 pressure of 20.6 MPa, which surpasses the theoretical maximum pressure (19.5 MPa) required for the fracturing of coal seams. During the entire gas extraction process, the CO2 concentrations in boreholes K1 and K3 decrease exponentially with time, showing attenuation coefficients of 0.0205 and 0.0231, respectively. The attenuation coefficients of the three attenuation stages of the original coal seam gas flow rate were 0.0314, 0.2142, and 0.1198, which were higher than those corresponding to the test area. The CH4 concentration in boreholes K1 and K3 in the test area were both higher than that in the original coal seam, and the maximum CH4 flow rates in these boreholes were 1.31‐ and 1.72‐fold higher than that in the original coal seam, respectively. The comparative analysis of CH4 concentrations and flow rates indirectly showed an improvement in the permeability of the coal seam. Further, a quantitative equivalent gas extraction evaluation method based on LCO2 fracturing of coal seam and gas displacement was proposed. Furthermore, based on a comprehensive evaluation, the effective displacement radius caused by the LCO2 fracturing test was 9 m, with a displacement efficiency of 23.95%, and a displacement volume ratio of 0.21. This method offered the possibility of realizing the quantitative evaluation of the LCO2 injection amount and the gas extraction effect, and provides a basis for optimizing the LCO2 fracturing of coal seams as well as the gas extraction process.

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Effect of initial temperature and H2 addition on explosion characteristics of H2-poor/CH4/air mixtures

Cited by 50 publications

References 67 publications

Experimental Study of the Influence of H₂/CO on the CH₄ Explosion Pressure and Thermal Behaviors

Experimental Study of the Influence of H₂/CO on the CH₄ Explosion Pressure and Thermal Behaviors

Research on the Damping Performance of Mining Highly Efficient Water-Retaining Colloidal Material Against the Spontaneous Combustion of Coal

Liquid CO ₂ high‐pressure fracturing of coal seams and gas extraction engineering tests using crossing holes: A case study of Panji Coal Mine No. 3, Huainan, China

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Effect of initial temperature and H2 addition on explosion characteristics of H2-poor/CH4/air mixtures

Cited by 50 publications

References 67 publications

Experimental Study of the Influence of H2/CO on the CH4 Explosion Pressure and Thermal Behaviors

Experimental Study of the Influence of H2/CO on the CH4 Explosion Pressure and Thermal Behaviors

Research on the Damping Performance of Mining Highly Efficient Water-Retaining Colloidal Material Against the Spontaneous Combustion of Coal

Liquid CO 2 high‐pressure fracturing of coal seams and gas extraction engineering tests using crossing holes: A case study of Panji Coal Mine No. 3, Huainan, China

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Product

Resources

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Experimental Study of the Influence of H₂/CO on the CH₄ Explosion Pressure and Thermal Behaviors

Experimental Study of the Influence of H₂/CO on the CH₄ Explosion Pressure and Thermal Behaviors

Liquid CO ₂ high‐pressure fracturing of coal seams and gas extraction engineering tests using crossing holes: A case study of Panji Coal Mine No. 3, Huainan, China