(388e) Experimental Investigation On the Influence of the Moisture Content On Coal Dust Explosion

The sensitivity of dust explosion is decided by the moisture content in particle to some extent. To investigate the effect mechanism of moisture on dust explosion is therefore of practical needs for the prevention and mitigation of dust explosion. In this work, systematical experiments were performed on pre-humidification coal dust explosions by using the Siwek 20 L vessel. The influences of moisture content on the ignition and explosion processes of coal dust had been studied by testing the lower heat value, explosion severity and explosive limit. Inhibition phenomena of moisture have been confirmed for various dust concentrations and particle size distribution. With the increase of moisture content, the ignition sensitivity of coal dust weakens significantly, and the lower heat value of coal dust reduces linearly. There exists a critical moisture content to fully suppress the explosion for the coal dust with a given size distribution. The suppressing effectiveness of moisture increases with the reduction of lower heat value of the coal dust, but weakens with the decrease of particle size. For the explosions of large size coal dust, the moisture mainly acts as the thermal sick due to its high heat capacity and heat of vapourisation. Consequently, the maximum explosion pressure and rate of pressure rise have a decrease in linear with the rise of moisture content. Moreover, the minimum explosive concentration increases linearly until the coal dust can not be ignited. For the explosions of small size coal dust, the variation of explosion severity and explosive limit is in accordance with that of the larger size dust under lower moisture content. While, when the moisture content is high enough, a suddenly enhanced inhibition on explosion severity and explosive limit can be observed for the explosions of small size coal dust. It has been verified that this enhanced inhibition is caused by the notable dust agglomeration emerged in the small size coal dust with high moisture content. In conclusion, to prevent coal dust explosion and, responsibly, determine the explosion parameters, the influence of moisture content should be taken into account.