Lei Ni

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.

The organic peroxides instability rating research based on adiabatic calorimetric approaches and fuzzy analytic hierarchy process for inherent safety evaluation

This article proposes a new method of instability classification of organic peroxides (ICOP) for assessing the risk of decomposition reaction of organic peroxides, based on the adiabatic calorimetric approaches and fuzzy analytic hierarchy process (FAHP). Tonset is set as instability possibility index. Maximal power density, adiabatic temperature rise, maximum pressure rate, and maximum pressure are set as instability severity index (ISI) with proper weightings by FAHP. Instability possibility index and ISI are converted into ICOP based on risk matrix. The organic peroxides instability can, therefore, be quantified and divided into four levels, acceptable, moderate risk, highly dangerous, and seriously dangerous. Thermal decomposition of di‐tert‐butyl peroxide 25 mass % and tert‐butyl hydroperoxide 68.4 mass % are tested with Vent Sizing Package 2 and Phi‐Tech 1 which has the function of Accelerating Rate Calorimeter, respectively. Thermal decompositions of other organic peroxides are presented from citation. The instability rating results of these organic peroxides are presented to illustrate the validity of the method.

Research on thermal runaway process of styrene bulk polymerization

In a strongly exothermic reaction process, any cooling system failure can lead to a serious accident. The present paper investigates the developments in a polymerization reaction system when thermal runaway occurs. Temperature of polymerization is the key parameter of interest. In this work, a kinetic model of styrene polymerization was used to predict reactor temperature using Aspen Plus software. An adiabatic process of styrene polymerization was simulated, and the results indicate that the reactor temperature is able to reach 260°C. When thermal runaway occurs, the degree of styrene polymerization is lower. Different conditions were employed to explore the influence of operating parameters. The results demonstrate that the higher the initial reaction temperature, the faster thermal runaway occurs, and that the greater the proportion of diluent is, the later the reactor reaches its TMAX.

Preparation and thermal hazard evaluation of 1,3,3,5-tetra(1H-tetrazol-5-yl)-pentane

A novel multicyclo-tetrazoles energetic material, 1,3,3,5-tetra(1H-tetrazol-5-yl)-pentane (TTZP), was prepared by 1,3,3,5-tetra(cyano)-pentane and sodium azide. The crystal structure is characterized by X-ray diffraction. The thermal stabilities and the kinetic parameters of TTZP were studied by differential scanning calorimetry (DSC) and adiabatic calorimetry (Phi-TEC). Starink method was employed to calculate the activation energy based on the DSC data. Due to the complex reaction mechanism, the traditional method for the adiabatic data which using an nth-order reaction was modified based on the Kinetics Committee recommendations of the International Confederation for Thermal Analysis and Calorimetry. Avrami–Erofeev equation which was selected for the adiabatic simulation has good performance on the calculation of activation energy and pre-exponential factor. Finally, the important safety parameters (self-accelerating decomposition temperature) was calculated and discussed.