Kinetics mechanism of spontaneous combustion of oil tank containing sulfur caused by Fe(OH) ₃

The main cause of the spontaneous combustion of oil storage tank containing sulfur is that the corrupt products of tank has some oxidation tendency, and they can induce the oil spontaneous combustion when they are self-igniting. The one of corrupt products of tank, the sulfurized product of Fe(OH) ₃, was simulated by the sulfuration equipment. Then the thermal analysis experiment was done. And the kinetic mechanisms of the corrupt products of Fe(OH) ₃ were studied by using the model-free method and master plots. The results show that the thermalgravimetric (TG) plot of the sulfurized product of Fe(OH) ₃ includes two stages of mass loss. The first oxidative reaction is up to the nucleation and nucleus growth mechanism and the kinetic model function is g(a)=[-ln(1-a)] ^0.6731, the activated energy is 124.25 kJ/mol and the pre-exponential factor is equal to 4.45×10 ¹³ s ^-1. The second oxidative reaction accords with the phase boundary reaction mechanism and the kinetic model function is g(a)=1-(1-a) ^0.45, the activated energy is 218.42 kJ/mol and the pre-exponential factor is equal to 1.07×10 ⁸ s ^-1.