EXPERIMENT-CALCULATED ESTIMATING OF THE MAXIMUM PARTICLE SIZE OF EXPLOSIVE MONODISPERSE DUST-AIR MIXTURE

It was considered the problem of primary (not requiring execution of firing tests) assess the degree of grinding of solid combustible material, from which dispersed material is explosive in a state of dustair mixture. Due to the complexity and non-obviousness of the existence of the general solution of this problem we studied a special case of dust-air mixture consisting of particles which form can be approximated by the ball. The concept of maximum particle size dcr conducive to the explosibility of polydispersed dust-air mixture is entered. As the first practical step in solving the main problem the mathematical model for estimation of the maximum size dcr * particle of explosive monodisperse dust-air mixture is developed. The initial data for this model are the experimental values of the lower concentration limit of flame propagation (LEL) through dust-air mixture for several polydisperse samples of combustible material of known distribution of particles. The main assumption of this model was the legitimacy of the application of Le Chatelier law for calculation of LEL of polydisperse material considered as a mixture of monodisperse factions. Defined dcr * for coke of lignite, PVC, aluminium and polyethylene, which were respectively 30, 38, 46 and 118 microns. They discussed the relationship between dcr and dcr * . There is the example of practical use of results of work in the field of explosion hazard of dust-raising industrial room.