Investigations on the flame propagation characteristics in methane and coal dust hybrid explosions

ZHOU Yonghao; GAN Bo; JIANG Haipeng; HUANG Lei; GAO Wei

doi:10.11883/bzycj-2021-0064

Volume 42 Issue 1

Jan. 2022

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ZHOU Yonghao, GAN Bo, JIANG Haipeng, HUANG Lei, GAO Wei. Investigations on the flame propagation characteristics in methane and coal dust hybrid explosions[J]. Explosion And Shock Waves, 2022, 42(1): 015402. doi: 10.11883/bzycj-2021-0064

Citation:

ZHOU Yonghao, GAN Bo, JIANG Haipeng, HUANG Lei, GAO Wei. Investigations on the flame propagation characteristics in methane and coal dust hybrid explosions[J]. Explosion And Shock Waves, 2022, 42(1): 015402. doi: 10.11883/bzycj-2021-0064

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Investigations on the flame propagation characteristics in methane and coal dust hybrid explosions

doi: 10.11883/bzycj-2021-0064

State Key Laboratory of Fine Chemicals, Department of Chemical Machinery and Safety Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China

Received Date: 2021-02-10
Accepted Date: 2021-11-22
Rev Recd Date: 2021-05-13

Available Online: 2021-12-01

Publish Date: 2022-01-20

Abstract

Abstract

To reveal the flame propagation mechanisms in the methane/coal dust hybrid explosions, the effects of coal type and methane concentration on the propagation characteristics of methane/coal dust hybrid explosion flame were experimentally investigated. Experiments were performed in a gas-solid hybrid explosion apparatus with methane concentrations below the lower explosive limit. The flame propagation images were captured by a high-speed camera and the flame temperature was recorded by a high-accuracy thermocouple. The results show that the volatile component is the dominant parameter in measuring the combustion characteristics of a certain coal type. With the increase of the volatile component, the combustion of the methane/coal dust flame gets enhanced. As a result, the flame propagation velocity increases and the flame temperature goes up. When the difference of the volatile component is small, due to the heat loss of the water evaporation, the combustion reaction of coal dust with lower water component is severer, the flame propagates more quickly. With the increase of the methane concentration, the combustion of the coal dust particle gradually transforms from the diffusion combustion of the released volatile components to the premixed combustion. The heat radiation and convection promotes the pyrolysis of the coal particle and the combustible substances are released, which maintains the continuous propagation of the hybrid flame. With the increase of the methane concentration, the hybrid explosion mechanism is transformed from the dust-driven type to the gas-driven type, and the combustion reaction gets enhanced. The methane/coal dust hybrid flame could be composed by five zones: unburned zone, preheated zone, gas combustion zone, multi-phase combustion zone and char combustion zone. Behind the flame front, large or the agglomerated particles could continue the combustion reaction, which is the multi-phase combustion zone. In addition, the combustion of the char develops the char combustion zone. The turbulent disturbance results in the distribution difference of the combustion materials, which leads to the interlacement of the different combustion zones.
- methane/coal dust hybrid explosion,
- flame propagation velocity,
- flame temperature,
- flame propagation mechanisms

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References(20)

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