A posteriori hazard analysis and feedback information of an accidental event in the grains storage of an agrochemical product

The present study concerns a hazardous event which occurred in an industrial storage tank of a ground insecticide. A preliminary post-accident approach of the hazard evaluation is performed. The rapid report of the presence of an unstable functional group in the active product and of its potential thermal instability (CHETAH indices) has led to complete this examination by an experimental study of thermal analysis using isotherm exposition measurement (DTA) or with temperature programming by differential scanning calorimetry (DSC) and oxidability tests (BAM). The apparent kinetics of decomposition of the active matter of the ground insecticide has been represented by a global Arrhenius law.

A model designed for the simulation of heterogeneous thermal runaways based on the numerical solution of the transient mass and energy balances has been further applied to define the critical conditions of the storage and simulate its behavior.

The results obtained during this analysis with the experienced feedback allowed us on one side to explain the hazardous event and especially on the other side to modify the operating protocol of the conditions of formulation of the active matter on the inert mineral support.     

阴燃中出现有焰火的理论初探

阴燃是一种自维持,不断传播的,异相反应的放热燃烧过程。典型的阴燃例子有蚝烟,地下煤矿的燃烧等。从热安全角度来看阴燃过程,不完全的氧化反应和可燃物热解都会产生很多的有毒气体,对人造成危害;另外在一定的条件下,阴燃还会突然转化为有焰火,进行更猛烈的燃烧,造成更大的破坏。     

相变材料填充率影响锂电池组热失控传播特性的实验研究

复合相变材料(PCM)应用于锂电池组的热管理是当前研究的热点。然而,PCM对锂电池组热失控传播特性的影响规律仍不甚明晰。实验研究了不同PCM填充率对锂电池组的影响,分析其热失控触发时间、最高温度、质量损失和热释放速率等参数变化规律。结果发现,添加PCM后,电池表面温度、CO和SO₂浓度均出现了不同程度的降低,但对热释放速率没有明显的影响。PCM填充率为0%和10%的电池组均发生了热失控传播,而30%、50%、100%的PCM填充率能有效阻隔热失控传播的发生。     

太空环境下锂离子电池热失控与火灾的研究展望

综述了锂离子电池的热失控机理,介绍了由于电池内部电解液、电池隔膜和电极材料分解的链式热反应过程而引发的热失控和火灾现象.同时,讨论了锂离子电池在微重力太空环境中可能产生的烟黑浓度倍增,加速火蔓延,火焰喷射等极端火行为.进而探讨了开展锂离子电池的低压、落塔和抛物飞行等地面实验模拟太空微重力燃烧的方法可行性,建立数值模型预...     

热颗粒和热辐射共同作用阴燃点燃松针燃料床:数值研究

建立了热颗粒和热辐射共同作用下阴燃点燃松针燃料床的二维数值模型,计算得到了热颗粒和热辐射单独点燃以及共同作用点燃的临界条件,分析了燃料床的点燃过程。与前人实验数据对比表明数值模型能够较好预测临界点燃条件。金属热颗粒单独作用时点火所需的临界温度与颗粒直径呈双曲线关系。金属热颗粒与热辐射共同作用时,临界辐射热通量呈现出随颗粒温度和直径的增加而显著减小的趋势。热辐射持续供热能有效维持表层炭氧化反应,两者共同作用下点燃危险性增加。研究同时发现,燃料含水率对共同作用下的临界辐射热通量有较大影响。     

An incident investigation on an unexpected loss of containment and damage to PHI-TEC II during acrylonitrile runaway tests

This article investigates a laboratory incident that occurred during the analysis of a thermal runaway reaction of acrylonitrile monomer. This failure, which was attributed to an human error, resulted in financial losses and corresponding unexpected results. The incident not only damaged the interior of the vessel and other instrument parts, but also exposed the researchers to considerable danger, necessitating their escape from the laboratory. The failure characteristics are discussed, and countermeasures are developed to prevent such a type of incident from reoccurring.     

Thermal risk analysis of cumene hydroperoxide in the presence of alkaline catalysts

Many studies have been performed to clarify the basic thermal runaway hazards and kinetics of cumene hydroperoxide (CHP) decomposition. However, materials that are incompatible with CHP have not been clearly identified. Alkaline solutions have been used as a catalyst to form dimethylphenyl carbinol (DMPC) and dicumyl peroxide (DCPO); however, these solutions also affect the reaction and storage temperature of CHP. In this study, thermal calorimeters, differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2), were used to compare the effects of various bases on the decomposition of CHP in cumene. Specifically, the exothermic onset temperature, change in pressure over time, self-heating rate and heat of decomposition were evaluated. Moreover, to appraise the degree of hazard associated with the use of CHP, the compatibility of CHP with various substances was analyzed, and a risk matrix for thermal runaway reactions was obtained. The results of the present study could be used to design safety procedures for the production of CHP and its derivatives.     

细水雾抑制18650型锂离子电池热失控实验研究

为研究细水雾灭火系统对18650型锂电池热失控的抑制效果,利用自设计实验平台进行抑爆实验,对比初爆与燃爆两个关键点及有无外部热源的温度变化图。研究表明,细水雾能够明显抑制18650型锂电池热失控,但施加细水雾的时间点对抑制效果影响较大,初爆后施加细水雾能够有效抑制,在燃爆后施加细水雾10s内温度降低200℃以上,但由于锂电池内部电解液复燃的特点,温度回升。温升速率的变化使得电池初爆的时间和温度分别提前了67.4%和44.4%,据此提出通过探测18650型锂电池初爆释放气体发现热失控发生并在最短时间内移除异常行为电池来控制电池热失控及其热量的异常传播。     

Comparison of criteria for prediction of runaway reactions in the sulphuric acid catalyzed esterification of acetic anhydride and methanol

Loss of temperature control is one of the major reasons that can lead to runaway reaction. This occurrence is commonly named thermal runway. The aim of this paper is the application of thermal runaway criteria in order to predict the onset of runaway phenomena and define the range of stability related to operating conditions in the reactor, with specific reference to the esterification of acetic anhydride and methanol catalysed by sulphuric acid tested in isoperibolic conditions. The isoperibolic calorimeter has also been used to obtain thermodynamic, kinetic and physical chemistry data necessary to develop a model for the reaction. Some runaway criteria applied in this work require a model for the process, so a model for the analyzed system been developed.Because of the modest reaction enthalpy and low activation energy this reacting system provide a severe test to the runaway criteria.In this work, various runaway criteria have been applied to the experimental and simulated data and the results obtained have been compared.     

水平燃料填充床反向阴燃传播及其熄灭分析

根据单步反应机理(仅包括燃料的氧化),建立了一维非稳态燃料填充床反向阴燃的数学模型。通过简化模型参数及大活化能渐近分析,得出了定性描述燃料反向阴燃传播的两个方程。结果表明:随着空气流量的增大,阴燃温度是不断上升的,但由于受到反向空气风流的影响,阴燃温度的增长幅度是逐渐变小的;阴燃传播速度却呈现出先增大后减小直至熄灭的变化趋势。这种变化趋势与前人的实验结果相一致。通过定性分析得出:在气体流量为零的情况下,燃料仍然可以发生阴燃,而维持阴燃不断传播所需要的氧气量源于反应区域周围气体的扩散。此外,也分析了燃料特性参数(如密度、孔隙率、比热、导热系数及活化能)对燃料阴燃温度和阴燃速度传播的影响。     

模组箱体空间内磷酸铁锂电池热失控及其传播行为研究

为了探究储能用锂离子电池在真实应用场景下的热失控及其传播行为特征,选用86 Ah方形磷酸铁锂(LiFePO₄)电池,对其在热滥用触发方式下的热失控行为及模组箱体空间与开放空间中的传播行为规律进行了实验研究。单体实验结果表明,电池热失控产生的高温烟气会导致模组箱体内沿高度方向出现明显温度梯度,模组底部与顶部温度测点的最大温差达118.4℃。传播实验结果表明,模组箱体空间内热失控电池通过产气及喷出高温电解液向其他电池传热,在热失控电池影响下,模组箱体空间内3块电池上表面所能达到的最高温度均高于开放空间实验12℃～150℃,模组空间内热失控电池向同侧两块电池的传热量高于开放空间实验225 kJ和44.4 kJ。但箱体环境中有限的氧气供给会减缓电池在热失控时的内部放热反应进程,模组箱体空间实验中电池热失控峰值温度较开放空间实验低33℃～145℃,并且模组箱体空间实验中热失控完全传播所用时间较开放空间实验滞后213 s。研究结果对于锂离子电池模组的安全设计和热失控传播阻隔具有一定的参考价值与指导意义。     

Cause analysis of the fire and explosion during crude oil desulfurization in China

A serious fire and explosion accident that resulted in massive crude oil leakage and severe environmental pollution occurred on 16 July, 2010, in Dalian Port, China. To investigate the root cause of accident and conduct a wide-range investigation, desulfurizing agent JH02, which has a similar ingredient to the desulfurizing agent HD used in Dalian Port, and TS02 were employed in this study to determine the role of desulfurizing agents in the accident. The thermal behavior of crude oil, desulfurizing agents, and their mixtures was measured by using a C80 calorimeter. By using the calorimetric data, the kinetic parameters of the chemical reaction, such as activation energy, pre-exponential factor, and self-accelerating decomposition temperature of crude oil, as well as JH02, TS02, and their mixtures, were calculated and compared. The results indicated that the direct cause of the accident was the thermal runaway initiated by the increasing instability of the crude oil–desulfurizing agent mixture. Excess pressure in the oil pipeline triggered the physical explosion, but it alone was not enough to cause a serious damage. Furthermore, a stable desulfurizing agent such as TS02 could not ensure a safe desulfurizing process. The results of this study would benefit the safety management of desulfurizing processes during production and storage.