Experimental Study on the Influence of Initial Pressure of Explosion of Methane-Coal Dust Mixtures - Summary

Experimental Study on the Influence of Initial Pressure of Explosion of Methane-Coal Dust Mixtures – Summary

1-Sentence-Summary: Hybrid explosion experiments are performed in a small scale rectangular chamber with varying initial pressures.

Authors: Y. Li, H. Xu, and X. Wang

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Experimental Study on the Influence of Initial Pressure of Explosion of Methane-Coal Dust Mixtures - Summary

The current authors present experimental results for hybrid explosion in a small-scale rectangular chamber. The chamber dimensions are 60cm long and 10 cm by 10 cm wide. The vessel contains glass side-walls so images of the flame propagation can be recorded. The mixture is ignited with a high-voltage spark discharge.

The methane gas concentration is held constant at 7% for all experiments. Coal dust concentrations are tested at 200 and 300 g/m3, and the mean particle diameter is 38.5 µm. Maximum pressure, maximum rate of pressure rise, and images of the flame structure are presented at initial pressures of 0.20, 0.25, 0.30, and 0.35 MPa.

Three of the main findings from this paper are:

  1. Maximum explosion overpressure increases with initial pressure in the chamber.
  2. Maximum rate of pressure rise increases more for high dust concentrations above 0.25 MPa initial pressure than lower dust concentrations.
  3. Flame wrinkling and folding occur as the initial pressure is increased, causing enhancement in reaction rate.

The following sections outline the main findings in more detail. The interested reader is encouraged to view the complete article at the link provided below.

Finding #1: Increasing initial pressure increases explosion maximum overpressure

The experimental results demonstrate that maximum overpressure of the hybrid mixture increases with initial pressure. For both 200 and 300 g/m3, the maximum overpressure increases by 10 to 15 kPa as initial pressure is increased from 190 to 350 kPa.

Finding #2: Increasing initial pressure increases explosion maximum rate of pressure rise

The experimental results also demonstrate that maximum rate of pressure rise increases with initial pressure. However, the impact on the two coal dust concentrations are markedly different. Both increase from 150 kPa/s to 325 kPa/s moving from 190 to 250 kPa initial pressure. Increasing the initial pressure to 350 kPa causes a further increase in maximum rate of pressure rise of 300 g/m3 to 950 kPa/s, but only increases the 200 g/m3 to 850 kPa/s.

Finding #3: Increasing initial pressure causes flame wrinkling and folding

High speed photographs of the flame show enhanced flame wrinkling and folding as the initial pressure is increase. Furthermore, the flame visually reaches the end of the chamber sooner under these conditions. Compared with the maximum pressure and maximum rate of pressure rise results, these findings illustrate more sever hybrid explosions at increased operational pressure.

My Personal Take-Aways From
“Experimental Study on the Influence of Initial Pressure of Explosion of Methane-Coal Dust Mixtures”

This paper is interesting for anyone studying hybrid flame propagation. It is also useful for any industries processing combustible dust or hybrid mixtures under increases operational pressures. The current paper demonstrates that enhanced explosion severity may occur under these conditions. This should be kept in mind when performing risk analysis and designing explosion protection strategies.

Full Citation:

  • Y. Li, H. Xu, and X. Wang, “Experimental study on the influence of initial pressure of explosion of methane-coal dust mixtures,” Procedia engineering, vol. 62, pp. 980-984, 2013.
    [Bibtex]
    @ARTICLE{Li2013,
    title={Experimental Study on the Influence of Initial Pressure of Explosion of Methane-Coal Dust Mixtures},
    author={Li, Y. and Xu, H. and Wang, X.},
    journal={Procedia Engineering},
    volume={62},
    pages={980--984},
    year={2013},
    link={http://www.sciencedirect.com/science/article/pii/S1877705813013337},
    summary={http://www.mydustexplosionresearch.com/experimental-study-influence-initial-pressure-of-explosion-methane-coal-dust-mixtures},
    }

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