Risk And Safety Control Measures For Typical Nitrification

With the continuous progress of human social productivity and the rapid development of chemical industry,people's demand for and use of chemicals is also increasing,and the frequency and consequences of accidents caused by the production of hazardous chemicals are becoming more and more serious.As a dangerous process,nitrification process has attracted more and more attention due to frequent accidents in recent years,so it is necessary to study and explore the risk of typical nitrification process.According to the characteristics of nitrification process,this paper selects nitro methane synthesis process and 2,4-dinitrochlorobenzene synthesis process to carry out the risk study aiming to obtain thermal risk data through thermodynamic and kinetic tests based on the risk factors and problems existing in the process,optimizing the technological conditions on the basis of comprehensive consideration of production and safety,and optimizing the treatment methods of dangerous by-products,so as to reduce the risk of by-products and achieve the purpose of resource recovery and utilization.The exploration of this paper not only fills the blank of hot air risk data of nitrification process to a certain extent,but also provides research ideas and methods for other nitrification processes.The thermal stability of nitro methane was studied by means of RSC rapid screening calorimeter and DSC differential scanning calorimeter.The thermal decomposition risk of nitro methane increased with the increase of purity.The initial decomposition temperature of nitro methane is 306.3 ?,and the heat release after decomposition is very large,the specific heat release exceeds 3000 J/g;Methyl nitrite,as a high-risk byproduct of nitro methane process,was tested by C600 micro calorimeter and ARC adiabatic calorimeter.The initial decomposition temperature of methyl nitrite was 141.8 ? and the specific heat release was 4300 J/gather decomposition of methyl nitrite is obviously affected by the initial pressure,the higher the initial pressure is,the easier the decomposition is.The initial pressure is higher than 0.85 Map,the initial decomposition temperature of methyl nitrite is obviously reduced,and the induction period of decomposition explosion is very short over 180?.According to the difficulty of treatment of methyl nitrite by-product,ethanol wasselected as absorption solvent by design absorption experiment.The optimum absorption temperature was-5 ? and the absorption rate was as high as 48.94%.Compared with pure methyl nitrite,the risk of decomposition of absorbent was reduced from 4 to 1,and the risk of thermal runaway was reduced from 4 to 2.It is proved that the absorption of methyl nitrite by ethanol not only solves the problem of by-product absorption in nitro methane process,but also reduces the hot air risk of by-product and can realize the recovery and reuse of by-product.To solve the problem of unstable production rate of nitro methane,the optimum conditions are 45 ?,reaction time 2 h,stirring speed 400 r/menthe method of one-time addition of dimethyl sulfate was corrected according to the results of isothermal heat experiment.The optimum feeding time was 150 min,compared with that of one addition.When the feeding time was 150 min,the reaction risk grade could be reduced from 3 to 1,thus solving the problem of strong exothermic reaction process which was criticized as nitrification reaction.The initial decomposition temperature of 2,4-dinitrochlorobenzene is 300.49 ? and the specific heat release is 1809.6 J/g,which belongs to grade 3 risk degree.After synthesizing the experimental data of thermal stability and thermodynamic data of reaction process,TP<MTSR<TD24<MTT,it is concluded that the corresponding reaction risk grade in the process is grade 2.In view of the dangerous characteristics of 2,4-dinitrochlorobenzene process,it is suggested that the purpose of safety production should be achieved by prolonging feeding time,detecting impurity content and corrosion protection.