Study On The Thermal Hazard Od H Vesicant

H vesicant is an important chemical raw materials,widely used in plastics and rubber products.Its production process belongs to the nitrosation process,which is a dangerous chemical process supervised by government.It is necessary to analyze the thermal hazards of the production process of H vesicant.In order to reduce the risk of process technology of H vesicant and realize the safe production of the enterprise,this paper carried out the thermal safety properties analysis of related substances and process for production of H vesicant by using instruments such as ARC,DSC,C80 microcalorimeter,RC1 e reaction calorimeter,HPLC and so on.The important conclusions are as follows:1.The thermal hazard analysis of the substances in the production of H vesicant show that sodium nitrite and urotropine are relatively stable,but H vesicant can decompose at about 200 ?.According to the determined thermal stability parameters,risk assessment is carried out from unilateral factors,and the dangerous level of H vesicant is assessed to be three,with a high explosion hazard.However,it is assessed to be two grade level of dangerous by using risk matrix method,is more dangerous eligible to accept.The starting decomposition temperature and self-accelerating decomposition temperature continue to decline with the increase in water content.When the water content is 6%,the exothermic reaction temperature decreases to 84.3 ?,and the self-accelerating decomposition temperature is only about 43 ?,and the thermal risk increases gradually.2.Reaction process risk analysis results for synthesis of H vesicant show that the thermal hazard of initial mother liquor is relatively small,there will be no decomposition.In the synthesis reaction process,the reaction temperature exhibit great impact on the thermal hazard of process and yield of product.As the reaction temperature increases in the range of 0~20 ?,the reaction rate is accelerated,the heat of reaction and thermal risk increase gradually.In addition,when the temperature exceeds 15 ?,a significant decline in yield occurs due to product decomposition.In the end of reaction,the decomposition temperature of the mixed solution containing water significantly reduce to between 60~80 ?,and the risk is relatively high.The effect of the feed rate on the risk of the process is mainly reflected in the heat accumulation,which can reduce the heat accumulation by extending the feeding time.When the reaction temperature is higher than 10 ?,the feed rate is less than 10 min,the process hazard level is five,and then the process need to re-design;when the temperature is below 5 ? and the feed rate is higher than 15 min,the process hazard level is two,which is a low-level risk.3.The thermodynamics studies on the decomposition of H vesicant reveal that the activation energy varies with the conversion rate(?).The activation energy required for the decomposition reaction increases rapidly as the reaction progresses when the conversion rate(?)is below 0.15,but rapidly reduced as the reaction progresses when the conversion rate(?)is in the range of 0.15<?<1.In the event of decomposition reaction,it is difficult to be terminated,so the decomposition of H vesicant is a high risk of reaction.Its adiabatic temperature in complete adiabatic state(phi=1)rise up to 900.5 ?,but can be reduced to 87.3 ? in good heat dissipation environment(phi=10).Packaging will affect the heat dissipation,and the accelerated decomposition temperature(SADT)of H vesicant packaging products is 128 ?.The decomposition will quickly break down when the temperature exceeds 128 ?,and very difficult to be controlled.4.Considering the effects of synthetic conditions on the thermal stability of the mixed materials,the heat hazard and yield in the reaction process,the safety conditions for synthesis of H vesicant are recommended as follows: the temperature of the reactor is between-5 ? and 5 ?,or even lower,and at the same time,the appropriate extension of the feeding time to 15 min or more to reduce the heat accumulation.Moisture should be avoided for H vesicant in the packaging,storage,transportation process,and stacking should ensure good ventilation and heat dissipation.The above research results have important theoretical significance for the improvement of H vesicant synthesis process and safety production.