Coal dust explosions in a spherical bomb

TLDR: In this article, the results of coal dust explosion experiments obtained by means of the Barknecht-Siwek 20 litre sphere are presented and discussed, which lead to an extension of the hazard limits for coal dusts with respect to data in the current literature.

Abstract: Results of coal dust explosion experiments obtained by means of the Barknecht-Siwek 20 litre sphere are presented and discussed. Several coal dusts have been tested at ambient conditions. The oxygen mass fraction and the initial pressure have been varied to test their influence. The data collected lead to an extension of the hazard limits for coal dusts with respect to data in the current literature. The maximum explosion overpressure depends linearly on the partial pressure of atmospheric oxygen. The ‘optimum’ dust concentration depends linearly on the oxygen concentration in the suspending atmosphere. This has led to a useful non-dimensional representation of the results: in the new variables, maximum explosion overpressure data for a coal dust at various values of the initial oxygen partial pressure are correlated by a single curve for all tests in which most of the oxygen is consumed. Differences in the maximum explosion overpressure exhibited by different coals could not be related to chemical parameters due to the prevailing effect of non-adiabatic explosions in this apparatus at such low rates of pressure rise. The maximum rate of pressure rise has been found generally to increase with the standard volatile matter content and with the hydrogen content in the coal.