The Optimization And Application Of Thermal Runaway Dynamic Parameters Computation Based On Adiabatic Calorimetry

The chemical industry forms the basement of almost all kinds of convenience in modern life,but also brings accidents and disasters.Reaction thermal runaway is one of the most common and dangerous causes of chemical industry accidents.And for the study on this area,various kinds of thermal calorimeters and analysis methods are indispensable.The adiabatic thermal calorimeters,such as ARC and VSP,can simulate the worst situation in the process of reaction runaway.It has been widely used in the research for reaction thermal runaway,including kinetic parameters computation,reaction risk assessment and emergency relief sizing.However,compared with the wide application in chemical safety research,the tool itself and its application methods are not realized thoroughly enough.The methods of reaction kinetic parameters fitting and thermal inertia corrections can be further simplified and improved,and there are even more mistakes and ignorance in the calculation of venting size.If the reaction is highly exothermic or corrosive,it may exceed the detection limit of the instrument or cause pipeline damage,resulting in the failure to obtain a complete exothermic curve.For such situation,a new calculating method of kinetic parameters is proposed.The ratio of conversion is used as the fitting object instead of the selfheating rate,and the fitting of activation energy E and pre-exponential factor A are separated.The incomplete exothermic curve can be processed accurately,which enlarges the application scope of adiabatic calorimetry.Then,this paper improves the method of thermal inertia correction.It discusses the selection of initial temperature in the process of experiment and data processing,combs and simplifies the phi correction method of temperature and self-heating rate.In view of the large error of the original TMR approximation formula and its lack of rigorous derivation process,this paper introduces the numerical integration method into the calculation of time interval in adiabatic process,which improves the calculation accuracy of TMR obviously.The accuracy and reliability of the above methods were verified by the experiments of 20wt% DTBP-toluene solution with different thermal inertia.Finally,based on the above improvements,the influence of thermal inertia on discharge design is further discussed.At present,the experiment data is often used directly in relief system sizing when the thermal inertia is close to production process.This paper selected three vapor system reactions and calculated their relief size with different thermal inertia,the results showed that the calculated relief size may change with thermal inertia much more smartly than that estimated by traditional correction methods.At the same time,the influence of thermal inertia on the relief area is different according to the design conditions and fitted calculation methods.For vapor system,Huff algorithm is more sensitive to thermal inertia than Leung algorithm.But in general,in order to obtain adequate and economic relief size,it is necessary to measure the heat capacity of reactors and material and conduct a complete thermal inertia correction procedure.