10. Combustion and Reacting Flows

Ammonium nitrate is widely used as a fertilizer. It is highly soluble in water and acts as an oxidizing agent, producing oxygen when heated above a decomposition temperature of approximately 210°C. Ammonium nitrate is generally stable but can cause explosions under certain conditions. Serious accidents involving ammonium nitrate include explosions at Oppau in 1921, Toulouse in 2001, and Lebanon in 2020. In this study, we investigated the thermal pyrolysis characteristics of wood treated with oxidant. Wood forms a porous structure made up of fiber structures of several tens of micrometers. Therefore, the liquid penetrates into the wood. The specimen used was cedar wood that interior had been impregnated with ammonium nitrate solution using a vacuum impregnation method. The wood of impregnation treatment was thoroughly dried. The heat and mass transfer of the gas phase and solid-gas interface during radiation heating was visualized using a Schlieren systems with large parabolic mirrors of 300 mm diameter. As a result, pyrolysis gases were emitted from the heated surface of the untreated wood at the start of heating. Thereafter, pyrolysis of the wood progressed slowly. On the other hand, wood containing ammonium nitrate showed different pyrolysis behaviors, such as the wood with impregnation treatment of the ejecting gas velocity was larger than that of normal raw wood.