Analysis on oxidation process of sulfurized rust in oil tank

The paper focuses on the oxidation process of sulfurized rust in crude oil tank. Firstly, one sort of rust was put into the sulfurization and oxidation experimental apparatus. The chemical compositions and phase of sulfurized rust were analyzed by energy-dispersive X-ray spectrometer–scanning electron microscope technique. The result shows that the main contents are S, Fe and O and give a short length of side and diamond appearance, and a large pore size in structure. The oxidation of sulfurized rust at ambient temperature was investigated, which transferred from electrochemical reactions to chemical reactions. The result of thermal decomposition experiment indicates that the product of electrochemical reactions is ferrous sulfate. Hereafter, the thermo-gravimetric/differential scanning calorimetric (TG/DSC) technique was used to evaluate the self-heating hazards of pre-oxygenized sulfurized rust. The given TG/DSC curves at different heating rates are similar. Every curve consisted of three weightlessness stages and two weight gain stages. The corresponding apparent activation energy values, most probable kinetic model functions and pre-exponential factor values were calculated by the Flynn–Wall–Ozawa method, the Achar–Brindley–Sharp–Wendworth method and the Kissinger method. The final results described the complexity of oxidation process of pre-oxygenized sulfurized rust.