Research On Dihydric Phosphate Salt Suppressant’s Preparation And Effects On Explosion

Based on the explosion suppression mechanism and the selecting principle of powder, this article selected dihydrogen phosphate salt as explosion suppressant. Methods that used ultrafined and dry surface modified to manage the powder suppressant, taking explosion characteristic parameters like the maximum explosion pressure and the maximum explosion pressure rise rate as the index, using silica powder as a reference, the effect of dihydrogen phosphate salt powder on coal explosion and coal-gas mixture explosion was studied, the effect of ignition energy, powder particle size and concentration on explosion suppression was also considered.The best modification conditions were obtained by the orthogonal test design and balance integrated analytic method, the combination were as follows:the amount of methyl hydrogen silicone oil was3%of the quality of dihydrogen phosphate salts, the amount of ethanol solvent was3times as much as the quality of silicone oil, film temperature was75℃, film forming time was40minutes. The amount of water added and silicone oil mass ratio was1in modification process.A series of explosion suppression experimental data showed that the power of dihydrogen phosphate salt has a certain effect on explosion inerting and initial suppression, and (NH4)H2PO4was better than KH2PO4and Ca(H2PO4)2in inerting of braize and mash gas explosion and initial suppression. Different kinds of powder suppressant has different effects by powder of concentration, in addition, the same kinds of powder had different inhibition degree on the pulverized coal explosion maximum pressure and the maximum explosion pressure rising rate. Under the same condition, the powder material has inhibitory effect on explosion maximum pressure in order of (NH4)H2PO4, SiO2, Ca(H2PO4)2, KH2PO4, while explosion maximum pressure rising rate in order of (NH4)H2PO4, KH2PO4, Ca(H2PO4)2, SiO2. Moreover, the results showed that, the powder concentration has great influence on the suppressant’s inhibitory effect when the explosion was lower strength or in initial stage of smaller explosive power, and there was a best explosion suppression concentration, which making (NH4)H2PO4dry powder best inhibitory effect for pulverized coal explosion. For the explosive mixture which containing concentration of750g/m3pulverized coal and concentration of7%gas, the (NH4)H2PO4powder can not be ignited by2kJ ignition energy, which had the same concentration and different partical size, in other words, the action of powder on inerting of coal dust explosion has nothing to do with particle size. The increasing of ignition energy will make suppression ability of powder suppressant to pulverized coal explosion a significant drop. Along with the ignition energy increased, the pulverized coal explosion Pmax and (dP/dt)max decreased from53%,86%to12%,29%respectively when the pulverized coal concentration was750g/m3.