Experimental study of overpressure evolution laws and flame propagation characteristics after methane explosion in transversal pipe networks

Niu, Yihui; Shi, Biming; Jiang, Bingyou

doi:10.1016/j.applthermaleng.2019.03.059

“…Such effect grew more significant as the branch length increased. A horizontal pipe network‐based gas explosion experiment system was developed by Niu et al 5 to investigate the explosion overpressure propagation of CH 4 at different concentrations, the result of which showed that an overpressure rising area developed at the horizontal pipe due to pressure wave superposition while the maximum explosion overpressure declined in the parallel branch after CH 4 explosion. In another experiment on mine gas explosion propagation performed in the bent pipeline by Zhai et al 6 , the pressure wave and flame interacted with each other at the bend, resulting in sharp rises in both explosion overpressure and flame propagation velocity.…”

Section: Introductionmentioning

confidence: 99%

Influence of branch pipes on the deflagration characteristics of methane in confined space

Lv

¹

,

Zhang

²

,

Ju

³

et al. 2020

Process Safety Progress

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To investigate the deflagration characteristics of CH4‐air mixture in confined space, fluid dynamic software Fluidyn was used to build numerical models that each consisted of a horizontal pipe and vertical branches to study the influence of different numbers of branch pipes on the deflagration propagation characteristics of CH4. Research findings suggested that the oscillation trend of the time history curve of pressure at the test point weakened and the peak initial deflagration pressure attenuated in an approximately linear manner with the increase of the propagation distance in the horizontal pipe. With the increase of the number of branches, the peak initial deflagration pressure at the same test point declined with an increasing amplitude. The vertical branch was found to have both “boosting” and “inhibiting” effects on flame propagation. And the inhibiting effect dominated as the number of vertical branches increased, which caused the flame propagation velocity within the horizontal pipe to significantly attenuate. In addition, the functions of the peak initial deflagration pressure varying with the number of branches and propagation distance in the horizontal pipe were obtained by fitting. According to the functions, the vertical branch had marked pressure venting effect on deflagration pressure in the horizontal pipe; the more the branch pipes were, the more significant the pressure venting effect was.

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“…e explosion suppression effect is related to the break-up time of the diaphragm and the position of the explosion flame front. Niu et al [26] established a complex transversal pipe network to study the overpressure evolution laws and flame propagation characteristics after methane explosion; these researchers found that a high-pressure area exists in the middle of the transversal branch, and the flame sustaining time and surface damage are minimal at the transversal branch. Sun et al [27] used numerical methods to investigate the explosion-proof distance and the propagation characteristics of gas explosions with four types of pipe crosssectional areas.…”

Section: Introductionmentioning

confidence: 99%

Influence of Cavity Width on Attenuation Characteristic of Gas Explosion Wave

Xu

¹

,

Mu

²

,

Li

³

et al. 2021

Shock and Vibration

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This study aimed to investigate the influence of cavity width on the attenuation characteristic of gas explosion wave. Attenuation mechanism of gas explosion wave through cavity was obtained by numerical simulation. The gas explosion shock wave energy can be greatly attenuated through the cavity structure in five stages, namely, plane wave, expansion, oblique reflection, Mach reflection, and reflection stack, to ensure that it is eliminated. Cavities with various width sizes, namely, 500 ∗ 300 ∗ 200, 500 ∗ 500 ∗ 200, and 500 ∗ 800 ∗ 200 (length ∗ width ∗ height, unit: mm), were experimented to further investigate the attenuation characteristics through a self-established large-size pipe gas explosion experimental system with 200 mm diameter and 36 m length. Results showed an evident attenuation effect on flame duration light intensity (FDLI) and peak overpressure with increasing cavity width. Compared with 300 mm, the overall FDLI decreased by 83.0%, and the peak overpressure decreased by 71.2% when the cavity width was 800 mm. The fitting curves of the FDLI and peak overpressure attenuation factors to width-diameter demonstrated that the critical width-diameter was 2.19 when the FDLI attenuation factor was 1. The FDLI attenuation factor sharply decreased at the width-diameter ratio range from 1.5 to 2.5 and basically remained steady at 0.17 at the width-diameter ratio range from 2.7 to 4.0. The peak overpressure attenuation factor gradually decreased with the increase of width-diameter ratio and changed from 0.93 to 0.28 with width-diameter ratio from 1.5 to 4.0. The research results can serve as a good reference for the design of gas explosion wave-absorbing structures.

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“…However, when the gas concentration was above 3 MPa, the upper limit of flammability was significantly increased. In the meantime, the theoretical limit of the oxygen concentration required for the explosion was gradually reduced, which increased the explosion hazard [17]. Researchers have conducted a lot of research on the reaction in the reactor, but they have not directly used the low-concentration gas effectively in the actual situation of a coal mine.…”

Section: Introductionmentioning

confidence: 99%

Oxidation and Characterization of Low-Concentration Gas in a High-Temperature Reactor

Chen

¹

,

Wen

²

,

Yan

³

et al. 2020

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To achieve the efficient utilization of low-concentration mine gas, reduce resource waste and alleviate environmental pollution, the high-temperature oxidation of low-concentration gas at a concentration range of 1.00% to 1.50%, which is directly discharged into the atmosphere during coal mine production, was carried out to recover heat for reuse. The gas oxidation equipment was improved for the heating process and the safety of low-concentration gas oxidation under a high-temperature environment was evaluated. The experimental results showed that the reactor could provide a 1000 °C high-temperature oxidation environment for gas oxidation after installing high-temperature resistant ceramics. The pressure variation curves of the reactor with air and different concentrations of gas were similar. Due to the thermal expansion, the air pressure slightly increased and then returned to normal pressure. In contrast, the low-concentration gas exhibited a stable pressure response in the high-temperature environment of 1000 °C. The outlet pressure was significantly greater than the inlet pressure, and the pressure difference between the inlet and outlet exhibited a trend to increase with the gas concentration. The minimum pressure difference was 4 kPa (air) and the maximum was 11 kPa (1.50% gas). The explosion limit varied with the temperature and the blend of oxidation products. The ratio of measured gas pressure to air pressure after oxidation was below the explosion criterion, indicating that the measured concentration of gas is still safe after the shift of the explosion limit, which provides a safe concentration range for the efficient use of low-concentration gas in the future.

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Experimental study of overpressure evolution laws and flame propagation characteristics after methane explosion in transversal pipe networks

Cited by 47 publications

References 17 publications

Influence of branch pipes on the deflagration characteristics of methane in confined space

Influence of branch pipes on the deflagration characteristics of methane in confined space

Influence of Cavity Width on Attenuation Characteristic of Gas Explosion Wave

Oxidation and Characterization of Low-Concentration Gas in a High-Temperature Reactor

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