Experimental investigation on the inhibition of coal dust explosion by the composite inhibitor of carbamide and zeolite

Coal dust explosion occurs violently at the atmosphere of coal gasification due to the combustible gas addition. To reduce the risk of dust explosion, a composite inhibitor with the combination of zeolite and carbamide was prepared and characterized. And the inhibition effects of the composite inhibitor with different mass fractions on the explosion pressure and flame propagation velocity were studied in a 20 L explosion spherical vessel, which were compared with that of carbamide and zeolite. The results indicate that the composite inhibitor showed an irregular morphology with the carbamide particles covered on the porous zeolite carrier by the bonding of agar. The best inhibition effect was reached for the composite inhibitor of carbamide and zeolite with the ratio of 1:1. And when the 50 wt% optimum composite inhibitor was added in the coal dust, the maximum explosion pressure and maximum rate of explosion pressure rise were reduced by 0.42 MPa and 23.871 MPa/s with the flame propagation velocity decreasing of 0.690 m/s. Furthermore, the inhibition mechanism of the composite inhibitor was presented by analyzing the samples and explosion residues.