基于分布式测温的流动热分析动力学方法

A thermal analysis kinetics method under flowing conditions based on distributed temperature sensing

面向连续流动生产过程反应风险评估和工艺优化的需求,针对其热力学和动力学测算方法开展了研究。通过分析管式反应器的热平衡和物料平衡设计了一种应用于流动状态下的热分析动力学方法,并依据测量原理搭建流动反应实验平台进行验证。首先,利用管路不同位置分布的温度传感器获取实验过程的温度分布,通过标定反应管路的等效总传热系数,结合温度分布分段的方式计算反应焓。其次,针对动力学分析过程通常忽略温度分布的问题,将热力学分析结果和反应器模型结合拟合动力学参数。以乙酸乙酯氢和氧化钠的水解反应为例设计实验,结果表明,合适的流量条件下,反应焓计算结果与釜式实验结果相当,但流动量热方法实验效率更高、实验过程更安全,活化能计算结果与文献值的相对误差小于3%。结合热力学和动力学分析结果以及反应器模型能够预测不同工况的温度分布,与实测值较吻合,为后续的反应风险评估和工艺优化提供了参考。

Addressing the needs for risk assessment and process optimization in continuous flow production,research was conducted to explore thermodynamic and kinetic calculation methods under flow conditions.By analyzing the thermal balance and material equilibrium of tubular reactors,a thermal analysis kinetics method applicable to flow conditions was designed.Subsequently,a continuous flow reaction experimental platform was constructed based on measurement principles for validation.Initially,temperature sensors distributed at various positions within the pipeline were employed to capture the temperature distribution during the experimental process.The equivalent overall heat transfer coefficient of the reaction pipeline was calibrated,and used in conjunction with segmented temperature distributions to calculate the enthalpy of the reaction.Subsequently,given the tendency to overlook temperature distribution in kinetic analyses,the study integrated calorimetric results and reactor models to compute kinetic parameters.The practicality of this approach was studied using the hydrolysis reaction of ethyl acetate and sodium hydroxide as an example.During the experiments,adjusting flow rates was employed to locate the peak temperature distribution,thereby enhancing the accuracy of calculated reaction enthalpy.The experimental outcomes revealed that under suitable flow conditions,the calculated reaction enthalpy closely matched results from batch experiments and established literature values.Moreover,the flow calorimetric method exhibited higher experimental efficiency,lower liquid holdup,and increased safety during the experiment.The kinetic analysis results were in close alignment with literature values,showing a relative error of less than 3%in the activation energy calculations.Combining calorimetric results with kinetic parameters allowed the use of reactor models to predict temperature distributions under varying conditions,demonstrating a close correlation with measured values.This serves as valuable guidance for subsequent risk assessments and process optimizations in the realm of reaction evaluation and procedural enhancements.