【作者】 张博；

【导师】 卫宏远；

【作者基本信息】 天津大学 ， 化学工程， 2020， 博士

【摘要】 化学工业在造福人类生活的同时,存在的各种安全问题也使人类社会遭受了巨大的损失。化工安全问题成为了一项世界性课题。近年来,国内外越来越多的学者投入到化工安全领域中来,相关的研究也得到了长足的发展。对于危险化学反应失控风险判据模型以及应用,目前还有待更进一步的深入研究和完善。本文以精细化工和制药行业常见的非均相危险化学反应体系为研究对象,针对反应动力学模型、热失控及热行为判据模型和热安全操作条件的优化算法进行了系统地研究。首先,对于伴有二氧化碳生成的催化加氢非均相危险化学反应,采用在线测定结合离线测定的方式,建立了表观动力学的表征方法。将离线高效液相色谱与在线原位红外测得的实验数据进行线性拟合,通过拟合效果判断原位红外数据的合理性,同时实现红外特征吸收峰高度的浓度标定。采用各温度下的实验数据,利用最小二乘法拟合目标反应的动力学参数,通过比较反应速率曲线的实验值与计算值判断动力学参数的合理性,最终建立反应的动力学模型方程。结果表明:对于此反应体系,在一定的温度范围内,原位红外可以准确追踪反应的实际进程;反应速率曲线的计算值与实验值非常接近,证实了本方法的有效性以及表观动力学方程的合理性。其次,针对非均相危险化学热失控及热行为模型研究,本文以恒温半间歇液-液非均相慢反应体系为研究对象,在充分考虑加料过程中体系移热能力变化的基础上,提出极限US假设,结合传统的理想假设并兼顾正常操作和冷却失效情形,通过体系的质量守恒和能量守恒方程,建立了目标反应的模型方程。通过数值模拟研究了冷却失效后合成反应的最高温度(MSTR)及其对应时间(θMTSR)的变化规律,并基于θMTSR建立了更具普适性的热行为(包括本质安全、未引发、热失控和QFS)判据。基于该判据建立了热行为边界图,同时提出了绝热温度图。综合利用边界图与绝热温度图,可以在兼顾目标反应、二次反应以及设备的技术极限的前提下,实现恒温半间歇液-液非均相慢反应热行为的有效判断。再次,反应体系的热行为识别,从本质上来讲可以视为一个模式识别问题,包括“特征”(用以表征热行为)的提取和识别两个阶段。传统判据通常只采用单一特征,可能无法充分表征各种热行为。本文从模式识别角度,针对恒温半间歇液-液非均相慢反应体系提取了多个特征,并通过多种模式识别算法对不同维数的特征进行识别。结果表明,5维特征结合支持向量机(SVM)可以达到最高的识别精度,二者构成多特征模式识别判据,定义为MFR判据。在此基础上,从本质安全角度出发,通过引入热安全上边界参数τj,MAT,结合MFR判据,构建了改进的广义本质安全区域。通过与传统判据进行比较,验证了 MFR判据的有效性和优越性。最后,基于θMTSR判据和MFR判据,建立了危险化学反应热安全操作条件的优化算法。在详细介绍优化算法建立过程的基础上,通过实际的案例研究,验证了判据及优化算法的有效性和实用性,进而可以更好地指导实际应用。更多还原

【Abstract】 While the chemical industry benefits human life,various safety problems make human society suffer huge losses as well.Chemical safety has become a worldwide issue.In recent years,more and more scholars at home and abroad have devoted to the field of chemical process safety,and the relevant research has made great progress as well.For the risk criterion models of hazardous chemical reactions and its application,further research and improvement are still needed.Taking the heterogeneous hazardous chemical reaction systems common in the fine chemical and pharmaceutical industry as the research objects,this paper will systematically study the reaction kinetic models,the thermal runaway and thermal behavior criterion models,as well as the optimization algorithms of thermally safe operation conditions.Firstly,for the catalytic hydrogenation reaction with carbon dioxide generation,an on-line measurement combined with the off-line measurements are employed to establish the characterization method of the apparent kinetics.Linear fits are performed between the experimental data measured by off-line HPLC and in-situ ReactIR,and the fitting performances are used to determine the validity of experimental data collected by in-situ ReactIR.At the same time,the absorption intensities of infrared characteristic peaks are converted to concentrations.Based on the experimental data at different temperatures,the kinetic parameters of the desired reaction are calculated by the least square method.The rationality of the kinetic parameters is indicated by the comparison between the experimental and calculated reaction rate curves.Finally,the kinetic model of the reaction is established.The results show that:for the studied reaction system,in-situ ReactIR can be used to accurately track the reaction process within a certain temperature range;the calculated curves of reaction rate are highly close to the experimental ones,confirming the validity of this method and the rationality of the apparent kinetic equation.Secondly,for the isoperibolic semi-batch liquid-liquid heterogeneous reaction systems,given the variations of heat transfer capacity of the system during the dosing period,the extreme assumption of US is proposed.Combined with the traditional ideal assumption and taking into account the normal operation and cooling failure scenarios,the mathematic model of the desired reaction is established based on the equations of mass balance and energy balance.The maximum temperature of the synthesis reaction under the completely cooling failure scenario(MTSR)as well as the corresponding time(θMTSR)are studied by numerical simulation.Based on θMTSR,a more general criterion,used for thermal behavior(including inherent safety,non-ignition,thermal runaway and QFS)determination,is established.Based on this criterion,a series of boundary diagrams are established.Due to the limitation of boundary diagrams,the novel adiabatic temperature diagrams are proposed.Employing boundary diagrams combined with adiabatic temperature diagrams,thermal behaviors of the isoperibolic semi-batch liquid-liquid heterogeneous reactions can be effectively determined on the premise of taking into account the desired reaction,secondary reaction and technical limits of the equipment.Thirdly,in essence,thermal behavior recognition can be regarded as a pattern recognition issue,including "feature"(used to characterize thermal behaviors)extraction and recognition.Traditional criteria usually use single feature,which may lead to the omission of important information and cause the different results.In this paper,from the perspective of pattern recognition,multiple features are extracted for the isoperibolic semi-batch liquid-liquid heterogeneous system,and the features of different dimensions are then identified through several pattern recognition algorithms.The results show that the combination of the 5-D features{f2,f3,f5,f4,f6)and the support vector machine(SVM)yields the highest recognition accuracy,which is then determined as the final multi-feature pattern recognition criterion,MFR criterion.On this basis,from the perspective of inherent safety,an improved generalized inherently safe region is constructed by introducing the thermally safe upper limit τj,MAT combined with MFR criterion.Compared with the traditional criteria,the effectiveness and superiority of MFR criterion are verified.Finally,based on the θMTSR criterion and MFR criterion,the optimization algorithms for the thermally safe operating conditions of hazardous chemical reactions are established.Based on the detailed introductions of the establishment process of optimization algorithms,the effectiveness and practicability of the criteria and the optimization algorithms are verified through the case studies,which can better guide the practical applications.更多还原