Study On Explosion Suppression Test Of Inert Powder On Sucrose Dust

In order to prevent sucrose dust explosion and reduce its perniciousness,the suppression effect of Al（OH）₃and NH₄H₂PO₄powders on the ignition sensitivity parameters and flame propagation of sucrose dust cloud are tested by1.2 L Hartmann tube and Godbert-Greenwald furnace.The suppression effect of NH₄H₂PO₄on explosion severity parameters of sucrose dust cloud is tested by 20 L spherical explosive test device.Finally the suppression mechanisms of Al（OH）₃and NH₄H₂PO₄are summarized,and their suppression effect on sucrose dust explosion will be compared.Researches show that:（1）In 1.2 L Hartmann tube,the minimum ignition energy（MIE）of sucrose dust clouds（250,333.3,416.7,500 g/m3）is 192.7,546.5,93.3,278.5m J respectively when the mass fraction of NH₄H₂PO₄reaches about 15%,30%,35%and 25%.The sucrose dust cloud is completely inert with the mass fraction of NH₄H₂PO₄further increasing.The mass fractions of NH₄H₂PO₄（48-74,38-47,25-37μm）that make 417.6 g/m3sucrose dust cloud completely inert is about 40%,35%,30%.The mass fraction of Al（OH）₃（48-74,38-47,25-37μm）that make 417.6 g/m3sucrose dust cloud completely inert is all 60%.（2）In Godbert-Greenwald furnace,the minimum ignition temperature（MIT）of sucrose dust clouds（666.7,888.9,1111.1,1333.3 g/m3）is 787,805,880 and 745℃respectively when the mass fraction of NH₄H₂PO₄reaches about 50%,55%,60%and 40%.The sucrose dust cloud is completely inert with the mass fraction of NH₄H₂PO₄further increasing.The mass fractions of NH₄H₂PO₄（48-74,38-47,25-37μm）that make 1111.1 g/m3sucrose dust cloud completely inert is about 65%,55%and 45%respectively,the mass fractions of Al（OH）₃（48-74,38-47,25-37μm）that make 1111.1 g/m3sucrose dust cloud completely inert is about 80%,80%and 70%respectively.（3）In 20 L spherical explosive test device,The parameter value of sucrose dust explosion sensitivity will be significantly reduced with mass fraction of NH₄H₂PO₄increasing.The maximum explosion pressure(P_max)and maximum rate of pressure rise(（dp/dt）_max)of sucrose dust will be greatly reduced with NH₄H₂PO₄increasing.The Kstmax of sucrose dust that adding NH₄H₂PO₄（48-74μm）is 14.794 MPa·m/s,the explosive hazard is classified to S_t1grade,and K_stmaxwill be decreased with particle size of NH₄H₂PO₄decreasing.The mass fraction of NH₄H₂PO₄that make sucrose dust（200-1000 g/m3）completely inert is 8-14%,the mass fraction of NH₄H₂PO₄（48-74,38-47,25-37μm）that make sucrose dust（150-500 g/m3）completely inert is 7-14%.（4）The suppression effect of NH₄H₂PO₄on the flame propagation of sucrose dust cloud is much better than Al（OH）₃,within a certain range of particle size,the smaller the particle size of inert powders are,the better the suppression effect will be.Al（OH）₃mainly relies on its physical inhibitions,such as diluting,hindering heat conduction and thermal radiation,to reduce the ignition sensitivity of sucrose dust cloud.The decomposition products of NH₄H₂PO₄with synergistic effect of physical suppression and chemical inhibition can react with free radicals（OH·and H·）that generated by sucrose dust combustion,and terminates the chain reaction of sucrose dust combustion.So the sequence of suppression effect on combustion and explosion of sucrose dust is NH₄H₂PO₄>Al（OH）₃.