绝热反应中热惯量对最大升温速率影响的研究

Impacts of Thermal Inertia on Maximum Self-Heating Rate of Adiabatic Reaction

绝热量热实验正在化工安全研究中得到日渐广泛的应用,而最大升温速率是实验中可以获取的重要数据之一.它既可以直观地表现反应的剧烈程度,又可以作为反应设备设计和泄放面积计算的依据.但目前的热惯量因子校正方法中,对最大升温速率的处理不够准确,有可能导致对反应风险的低估.针对上述问题,对 20%过氧化二叔丁基(DTBP)-甲苯溶液进行了绝热量热实验,计算了当体系热惯量在 1.0~2.0 范围内变化时的最大升温速率,发现绝热反应过程中最大升温速率与热惯量因子间的关系可以近似表示为幂函数的形式.对过氧乙酸(PAA)、40%过氧化甲乙酮(MEKP)和 15%过氧化异丙苯(CHP) 3 种不同反应级数的物质,基于文献值进行了类似的计算,证明了上述规律同样适用于其他分解机理为 n 级反应的物质.为了便于不同物质间的比较,将不同热惯量下的最大升温速率与热惯量为 1 时的最大升温速率之比记作 M.通过控制变量的方法,研究了物料动力学参数和环境条件对 M 的影响,发现活化能E、绝热温升Δ T和反应级数n 3个参数的影响最为明显,并据此建立了一种估算不同热惯量下最大升温速率的方法.该方法涉及到图表的查阅但在实际应用中可以得到较大程度的简化,而且相较于目前由DIERS推荐使用的最大升温速率校正方法可以得到更加准确可靠的结果.

The adiabatic calorimetric test is extensively used in chemical safety research,and the maximum selfheating rate(MSR) provides important experimental data. The MSR can reveal the severity of the reaction and provide basic information for designing reactors and identifying areas requiring emergency relief. However,the existing correction method for thermal inertia factor is not sufficiently accurate for calculating the MSR,which can lead underestimations of the reaction hazard. To solve this problem,we conducted an adiabatic thermal experiment using a 20% di-tert-butyl peroxide-toluene solution,and calculated the MSR of this system while varying the thermal inertia value from 1.0 to 2.0. We identified that the relationship between the MSR and thermal inertia can be approximately expressed using a power function model. Moreover,we calculated the MSR values at different thermal inertia values of peracetic acid,40% methyl ethyl peroxide,and 15% cumene peroxide,as reported in the literature. The results confirm that the power function model is applicable to other substances that follow the n-order decomposition mechanism. To facilitate comparisons of different substances,we propose the concept of the relative MSR M,which is the MSR value at a given thermal inertia divided by the MSR with a thermal inertia value of 1. We investigated the impacts of the kinetic parameters and environmental conditions on M and found that the activation energy E, adiabatic temperature rise ΔT,and reaction order n are most influential. Then,we developed and proposed a method for estimating the MSR at different thermal inertia values,which involves identifying a given figure but can be simplified to some extent in practical applications. This method is more accurate and reliable than that recommended by DIERS.