The Minimum Ignition Energy of Coal Dust in an Oxygen Enriched Atmosphere

In oxy/fuel combustion of coal, the pulverised coal is burned with oxygen at concentrations greater than the currently allowed value of 21 %. This may well provide advantages in carbon sequestration against other technologies such as pre-and post-combustion capture. However the risk of dust explosions increases significantly with increasing oxygen concentration and temperature. In this study the influence of enriched oxygen concentrations is researched on the dust explosion characteristics of Indonesian (Sebuku) coal dust and of Pittsburgh coal n degrees 8. First the ignition sensitivity characteristics (minimum ignition energy and minimum ignition temperatures) and explosion severity characteristics (maximum explosion pressure, Pmax, and maximum rate of pressure rise, Kst) are determined in air. Thereafter the minimum ignition energy is determined of both coals in an oxygen enriched CO2 atmosphere. The minimum ignition energy in air of the Sebuku coal was equal to 55 mJ, while the minimum ignition energy of the Pittsburgh coal was higher than 1000 mJ. The ignition sensitivity in a 30 vol% O-2 in CO2 mixture was in good agreement to the ignition sensitivity in air. In a 50 vol% O-2 in CO2 mixture the ignition energy decreased significantly to a value of 1.4 mJ for the Sebuku coal and 4.7 mJ for the Pittsburgh coal n degrees 8.