| With the rapid development of chemical and petroleum chemical industry, the chemicals which were flammable, explosive, toxic, harmful and corrosive, were used widely and increased sharply, but they also frequently caused various accidents. There were many dangerous substances involved in nitration of benzene progress, such as nitrobenzene, multi-nitrobenzene and nitrophenol salt, which could result to explosion by decomposition. Because of the smaller size of nitrobenzene facilities than oil refining device, researchers both domestic and foreign put tiny focus on security of nitrobenzene progress. With the expanding size of nitrobenzene device, the risk of accidents also increased, in addition to the lack of awareness of risk factors in process, accidents in nitrobenzene device were occur frequently, which even endangered people's lives. In order to reduce or avoid the occurrence of explosion, it was necessary to analysis the main risk factors comprehensively in nitrification of benzene process.According to the domestic and foreign research on explosion of nitrobenzene device, we investigated and identified the risk factors used fault tree analysis. We found that many factors could result in explosion of nitrobenzene plant, included long device operation cycle, not enough cooling in parking process, long stay of reaction materials, by-products increased, emulsification, leakage of air and the impact of materials. Dangerous levels of nitrobenzene were analyzed by Mond evaluation and fire, explosion, toxicity index of distillation unit were also calculated.Major dangerous substances in nitrification of benzene were selected and analyzed. Main risk medium in process of nitrobenzene were ensured, included benzene, nitric acid, sulfuric acid, sodium hydroxide, nitrobenzene and multi-nitrobenzene. In this paper, though thermal hazards of dangerous chemicals we determined the nitrobenzene, multi-nitrobenzene and nitrophenols salt as the main object to experiment and study.C80 simultaneous thermal analyzer were used to study the thermal stability of nitrobenzene, m-nitrobenzene and nitrophenol sodium salt. Exothermic reaction starting temperature, heat rate and reaction kinetic parameters were tested by the same time. Results of differential scanning calorimetry analysis showed that nitrophenol sodium salt had a significant exothermic peak in 310℃and TG analysis showed that 30% mass loss of the sample; As the temperature increased furthermore, in air atmosphere, the sample would react with oxygen and loss another more 20% mass. Nitrobenzene and m-nitrobenzene in the test range (from room temperature to 300℃) had no exothermic peak, but dinitrophenol sodium would react when heated to 235℃.To solve the volatilization of some liquid sample in the opening test in volatile, RSD rapid screening instrument which had a sealed pool was used for thermal analysis. Curves of temperature-programmed and pressure were used to study the effect of temperature on thermal decomposition of the dangerous medium. Thermal stability of nitrobenzene, dinitrophenol sodium salt and mixture of them were researched. In the test range (from room temperature to 400℃), dinitrophenol sodium salt had obviously effect on thermal stability of nitrobenzene when added a few. Thermal decomposition of the solution would decrease and the risk of nitrobenzene solution increased.Based on the major risk data acquired by synchronous thermal analysis and C80 calorimetry, and though the reaction activation energy, reaction order, self-accelerating decomposition temperature and time to reach the maximum reaction rate to analyze the thermal safety of the process and simulated possible occurs of runaway reactions. The actual safety operating parameters and technical support were offered for industrial production.Through the risk analysis and research of thermal damage of risk components, in combination with the actual conditions of industrial production, we proposed reliable accident prevention measures and contingency plans.
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