Thermal hazard and safety relief of benzaldehyde oxime

Benzaldehyde oxime is an important pharmaceutical and agrochemical intermediate, which releases a huge amount of heat under runaway condition. It has a low initial decomposition temperature, and may cause accidents without proper temperature control during production and storage. Thermal hazards of benzaldehyde oxime were investigated by using a high-performance adiabatic calorimeter (PHI-TECII) in order to understand its thermophysical properties. The results showed that benzaldehyde oxime would suffer from thermal decomposition until 381.86 K, the adiabatic temperature rise (ΔTad) and specific heat release (q') were 279.65 K and 548.1 J g−1, respectively. Furthermore, non-linear fitting was performed on data obtained from the PHI-TECII tests, the activation energy (E) and reaction order (n) of this decomposition was obtained as 176.24 kJ mol−1 and 2.2. The self-accelerating decomposition temperature (SADT) of the standard packages of 25 kg was calculated to be 323.07 K, indicating that the probability of combustion and explosion caused by runaway during the thermal decomposition is high. Benzaldehyde oxime could thus be classified as an autoreactive substance. The pressure-controlled and temperature-controlled bottom relief areas calculated by the Boyle' s Law and the Tangren' s Law were 4.51 × 10−4 m2 and 0.43 × 10−4 m2, respectively. For untempered hybrid system, the employment of temperature-controlled bottom relief is more effective.