Thermal risk in batch reactors: Theoretical framework for runaway and accident

Thermal safety and risk of accidents are still challenging topics in the case of batch reactors carrying exothermic reactions. In the present paper, the authors develop an integrated framework focusing on defining the governing parameters for the thermal runaway and evaluating the subsequent risk of accident. A relevant set of criteria are identified in order to find the prior conditions for a thermal runaway: failure of the cooling system, critical temperature threshold, successive derivatives of the temperature (first and second namely) vs. time and no detection in due time (reaction time) of the runaway initiation. For illustrative purposes, the synthesis of peracetic acid (PAA) with hydrogen peroxide (HP) and acetic acid (AA) is considered as case study. The critical and threshold values for the runaway accident are identified for selected sets of input data. Under the conditional probability of prior cooling system failure, Monte Carlo simulations are performed in order to estimate the risk of thermal runaway accident in batch reactors. It becomes then possible to predict the ratio of reactors, within an industrial plant, potentially subject to thermal runaway accident.     

Diphenylmethane diisocyanate self-polymerization: Thermal hazard evaluation and proof of runaway reaction in gram scale

Thermal analysis by differential scanning calorimetry and thermogravimetric/differential thermal analysis mass spectrometry, adiabatic calorimetry, a gram-scale heating test, and infrared spectroscopy were performed to evaluate the thermal hazards of diphenylmethane diisocyanate (MDI) and prove the occurrence of a runaway reaction. The self-polymerization of MDI was found to occur at about 340 °C under rapid heating conditions. Carbon dioxide was eliminated and heat was generated to allow polymerization. Under adiabatic and closed conditions, the runaway reaction of MDI can begin at least from 220 °C. Besides it is highly probable that the runaway reaction of MDI can begin from a lower temperature in an actual process scale. More heat was generated than in the previous case and the pressure rose rapidly. A closed 2-mm-thick glass vessel exploded because of the runaway reaction of MDI even if the temperature was lower than 300 °C. Therefore, MDI could cause fatal runaway reactions below 300 °C, where MDI had been assumed to self-polymerize by eliminating carbon dioxide previously.     

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.     

图书馆的火灾隐患及对策

论述了火灾对图书馆的危害 ,分析了火灾原因和隐患 ,并提出了防范措施和消防设备。     

BIPB的热分解动力学和失控反应模拟

为了评估双(叔丁过氧基)二异丙苯(BIPB)的热危害,对其热分解过程进行多速率的动态扫描C80热分析,用几种简单的热危害评估方法分析其热危害。然后应用模式法、无模式法(Friedman微分等转化率法)分别对试验结果进行处理,得到分解动力学数据,并用ASTM E 698法得到活化能数据,同时用C80、ARC和DSC的试验数据验证分解动力学数据的可靠性。最后利用无模式法的分解动力学数据进行BIPB绝热条件下和非绝热的2m3球形容器中的失控反应模拟,得到类似工艺条件下BIPB的安全控制温度。     

中国石化开展安全隐患排查治理的方法与成效

石油石化行业具有"高温高压、易燃易爆、有毒有害、连续作业、链长面广、能量集中"的特点,任何隐患都可能引发重大安全事故。"十一五"以来,中国石化牢固树立科学发展、安全发展的理念,坚持"安全第一、预防为主、综合治理"的方针,将隐患排查治理作为安全工作的重点,建立健全"排查常态化、治理规范化、投入制度化、防治系统化"为重点的隐患排查治理长效机制,分别对电气、仪表、储罐、海(水)上等专项隐患进行集中排查和治理,为公司安全发展提供强有力支撑,使得公司最大限度提升了安全保障水平,最大限度杜绝了重特大事故发生。     

A comparative analysis between temperature and pressure measurements for early detection of runaway initiation

In this work, we have analysed the use of pressure instead of temperature measurements for the early warning detection of runaway initiation. This is possible due to the fact that our runaway criterion, i.e. div>0, does not depend specifically on which state space variable we are using for divergence calculation. A series of runaway experiments, carried out in a 250 l pilot-scale reactor, has been used to compare the results. In accordance with previous analysis, we show that by using temperature, early detection of runaway initiation is achieved. Analogously to temperature, pressure may be also used for runaway detection. By comparing the different types of reactive systems analysed (vapour and gassy), it can be observed that temperature works better, in terms of earlier detection, than pressure but the differences are more pronounced for vapour than for gassy systems.     

国内外石油化工企业隐患治理工作探讨

无论国内、国外的企业,隐患治理工作都是企业安全管理工作的重要一环.国内外石油化工企业为达到保障生产经营平稳安全运转,针对安全设备、设施存在的隐患,投入专项资金,进行隐患治理.我国的隐患治理工作从加强隐患排查,突出重大隐患监控,不断提升安全保障水平入手,为实现企业安全平稳生产奠定了基础.国外隐患治理工作作为风险管理的一部分,具有风险评估和投资决策更量化的特点,可以为我们进一步提升隐患治理工作开拓思路.     

矿井进风流与围岩的换热

文章以热工学的基本原理和相关理论为基础,运用仪器对巷道进风流及巷道围岩周壁的温、湿度分布进行了测试。基于热传递的相关概念与机理以及矿内传热学基础,通过对巷道进风流与巷壁换热过程的分析,得出了进风平巷内风流与围岩间的对流换热系数和两者之间的潜热与显热交换之间的关系,并给出了相关的计算公式。     

Ethics and fundamental principles of risk acceptance criteria

Ethics are concerned with distinguishing between what actions are “right” and “wrong” and what values are “good” and “bad”, etc. and there is a long academic tradition in discussing ethics and ethical theories. Risk acceptance criteria, on the other hand, distinguish between levels of risks that are acceptable and levels that are intolerable. In some sense, one may say that risk acceptance criteria distinguishes between “good” and “bad” systems and activities with regards to the risk they expose the society or elements of a society to and there is thus an obvious link between ethics and risk acceptance criteria or to risk management at large. However, there are few references in the literature that explores this link, and in this paper, the ethical foundation of fundamental principles of risk acceptance criteria will be elaborated upon.This paper considers some important principles for establishing risk acceptance criteria for safety critical systems and activities. The various principles and the philosophies behind them might at first sight seem contradictory and exclusive, but it is demonstrated how they may coexist in one and the same regulatory regime; They may complement each other in order to achieve the overall safety objectives of society. Then, some brief considerations of the ethical foundations for the principles will be given and some relevant examples of actual risk acceptance criteria will be given from the maritime industries. However, it is believed that the principles and discussions are of general interest and apply to all areas of technical risk and to safety regulations in a broader perspective.     

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.     

BLEVE火球热辐射及其影响评价模型介绍

高压液化易燃、易爆化学品储罐易发生BLEVE,引起热辐射,会造成周围人员伤亡和设备损坏.介绍了BLEVE火球热辐射及其影响模型,通过该模型可以计算BLEVE火球的尺寸、持续时间、升空高度、热辐射通量及预测暴露在BLEVE火球热辐射通量下人的致死概率.     

硝酸铵与硝铵磷热稳定性对比研究

为了研究硝铵磷的热稳定性,用DSC－TG同步热分析仪测试了硝酸铵的热分解过程,根据升温速率分别为5,10,15 K／min的DSC和TG－DTG曲线,利用Ozawa法和Kissinger法求得的硝酸铵的活化能基本一致。用Rogers公式和Arrhenius公式求得指前因子和速率常数分别为1．62×1010 s－1,1．07×10－18 s－1（120℃）;硝酸铵在升温速率为5 K／min时,分解峰值温度的活化焓、活化熵、活化自由能分别为102．76 kJ／mol ,－62．35 J／（K·mol ）,134．98 kJ／mol;对比了硝酸铵和硝铵磷的DSC曲线,结果表明硝铵磷的吸热分解峰值温度低于硝酸铵,热稳定性更好。     

国家职业卫生示范企业评选标准解读

基本框架国家职业卫生示范企业评选标准严格按照《职业病防治法》的要求制定,以表格化详细列出,包括项目、内容、一票否决项、评分标准要点及依据等栏目。主要内容内容栏目包括12大项97个小项,根据权重对每项进行赋分,共1000分。在97个小项中,一票否决项为11项,其中组织机构和规章制度建设赋分最多,为190分,占总分的19%,一票否决项为5项,占否决项的45%,这表明职业病防治工作必须包含最高决策者承诺、建立相关组织、纳入生产经营目标管理并有经费保障等几项内容,否则就难以开展。在评审过程中,首先审查是否有一票否决项,如存在符合一票否决项…     

太阳能热泵系统中的蓄热技术

开发新能源和节能是寻找能源出路的两大途径,太阳能热泵系统以其显著的节能性和环保性具有广阔的发展前景.论述了太阳能热泵系统中的蓄热原理和蓄热材料,介绍了实际蓄热工程,进行理论分析,指明了今后的研究与发展方向.太阳能蓄热装置的开发与应用对太阳能热泵系统的发展具有深远意义.     

基于Voronoi图和时间效应的矿柱失稳预测

针对香炉山大规模地下采空区,借助Voronoi图确定分摊面积来模拟矿柱荷载分布、矿柱破坏、荷载转移以及荷载重新分布的过程,从而确定现阶段的不稳定矿柱,并在此基础上考虑时间效应。用该方法可得出,目前香炉山钨矿不稳定矿柱的失稳不会造成大规模的坍塌,考虑时间效应,则20年时间效应内二四坑口的南区有发生连续坍塌的可能。为防止矿柱发生大范围坍塌,结合香炉山钨矿的实际情况,最终确定胶结充填法为该矿山当前处理空区的最适宜方法。     

人体冷暖舒适性及服装保暖材料

众所周知，人是一个恒温的生物体，人体的核心温度一般保持在37℃左右，偏离该温度轻则会使人感觉不舒适，重则对人体造成伤害．甚至危及到生命安全。在人类实际的生产生活中．外界环境的温度大多和人体所需要的温度范围不一致。冬天，特别是在我国北方地区，最低可达-30℃～-40℃。在一些需要低温的工厂，例如冷库等．也