氨分解装置中液氨储罐火灾爆炸危险性分析

以某金属处理企业氨分解装置中液氨储罐罐区为例,对液氨泄漏后火灾爆炸事故及其伤害范围进行了研究,用池火、蒸气云爆炸和沸腾液体扩展蒸气爆炸模型进行计算分析,给出火灾、爆炸事故的人员伤害和财产损失范围。结果表明:围堤堤内池火或罐内池火时,罐区建构筑物内的汽化器、管道等设备会因直接过火或热辐射导致损坏,建筑内人员死亡,但难以波及罐区之外;蒸气云爆炸产生相当于1192.72kgTNT爆炸的当量,爆炸的后果严重,应重点防范,防范的重点为液氨泄漏、点火源;沸腾液体扩展蒸气爆炸的火球半径56.1m,持续时间8.7s,死亡半径27.2m,其源于储罐受热或系统突然失效,液体瞬时泄漏汽化并遇点火源而发生,具有突发性且后果严重,企业应高度重视并严格储罐及系统的定期检验与校验、密切关注系统的有效运行。     

Assessing the hazards from a BLEVE and minimizing its impacts using the inherent safety concept

Many worlds' major process industry accidents are due to BLEVE such as at Feyzin, France, 1966 and San Juan Ixhuatepec, Mexico City, 1984. One of the approaches to eliminate or minimize such accidents is by the implementation of inherently safer design concept. This concept is best implemented where the consequence of BLEVE can be evaluated at the preliminary design stage, and necessary design improvements can be done as early as possible. Thus, the accident could be avoided or minimized to as low as reasonably practicable (ALARP) without resorting to a costly protective system. However, the inherent safety concept is not easy to implement at the preliminary design stage due to lack of systematic technique for practical application. To overcome these hurdles, this paper presents a new approach to assess process plant for the potential BLEVE at the preliminary design stage and to allow modifications using inherent safety principles in order to avoid or minimize major accidents. A model known as Inherent Fire Consequence Estimation Tool (IFCET) is developed in MS Excel spreadsheet to evaluate BLEVE impacts based on overpressure, radiation heat flux and missile effects. In this study, BLEVE impacts are the criteria used as the decision-making for the acceptability of the design. IFCET is integrated with iCON process design simulator for ease of data transfer and quick assessment of potential BLEVE during the design simulation stage. A case study was conducted to assess of potential BLEVE from a propane storage vessel at the design simulation stage using this new approach. The finding shows promising results that this approach has a potential to be developed as a practical tool.     

锅炉BLEVE爆炸能量及其效应研究

将满足条件的锅炉纳入到重大危险源进行申报登记和管理体现了“预防为主”的先进管理理念，为了实现此目的，需要对锅炉爆炸能量及其效应进行深入研究，并在此基础上，才能提出锅炉重大危险源的分类和判别指标。文中建立了计算锅炉BLEVE爆炸能量的物理模型，编制了计算程序，并进一步给出了爆炸冲击波效应和爆炸伤害概率模型。该成果为预测锅炉爆炸能量、实现锅炉分级管理提供了理论依据。     

高温下油品生产中的风险分析及防范措施

高温条件下油品生产过程中安全防护措施考虑不充分或者操作不当,会发生突沸窜油和自燃着火事故.通过对高温下油品危险性分析,论述了高温条件下油品在储存、运输及混合等操作时应注意的事项.     

Numerical study of medium to large scale BLEVE for blast wave prediction

So far, the prediction of blast wave generated from the Boiling Liquid Expanding Vapour Explosion (BLEVE) has been already broadly investigated. However, only a few validations of these blast wave prediction models have been made, and some well-established methods are available to predict BLEVE overpressure in the open space only. This paper presents numerical study on the estimation of the near-field and far-field blast waves from BLEVEs. The scale effect is taken into account by conducting two different scale BLEVE simulations. The expansion of pressurized vapour and evaporation of liquid in BLEVE are both modelled by using CFD method. Two approaches are proposed to determine the initial pressure of BLEVE source. The vapour evaporation and liquid flashing are simulated separately in these two approaches. Satisfactory agreement between the CFD simulation results and experimental data is achieved. With the validated CFD model, the results predicted by the proposed approaches can be used to predict explosion loads for better assessment of explosion effects on structures.     

An innovative and comprehensive approach for the consequence analysis of liquid hydrogen vessel explosions

Hydrogen is one of the most suitable solutions to replace hydrocarbons in the future. Hydrogen consumption is expected to grow in the next years. Hydrogen liquefaction is one of the processes that allows for increase of hydrogen density and it is suggested when a large amount of substance must be stored or transported. Despite being a clean fuel, its chemical and physical properties often arise concerns about the safety of the hydrogen technologies. A potentially critical scenario for the liquid hydrogen (LH₂) tanks is the catastrophic rupture causing a consequent boiling liquid expanding vapour explosion (BLEVE), with consequent overpressure, fragments projection and eventually a fireball. In this work, all the BLEVE consequence typologies are evaluated through theoretical and analytical models. These models are validated with the experimental results provided by the BMW care manufacturer safety tests conducted during the 1990's. After the validation, the most suitable methods are selected to perform a blind prediction study of the forthcoming LH₂ BLEVE experiments of the Safe Hydrogen fuel handling and Use for Efficient Implementation (SH₂IFT) project. The models drawbacks together with the uncertainties and the knowledge gap in LH₂ physical explosions are highlighted. Finally, future works on the modelling activity of the LH₂ BLEVE are suggested.     

An experimental study of an LPG tank at low filling level heated by a remote wall fire

This paper describes an experimental study of 2300 L pressure vessels exposed to remote fire heating by a natural gas fuelled wall fire simulator. The tanks were filled to 15% capacity with commercial liquid propane. The flame intensity and distance were varied to study the effect of different heating levels on the tank and its lading.The fire simulator is first characterized with tests including fire thermocouples, radiative flux meters and thermal imaging. With the appropriate positioning of a target tank it is possible to get very realistic fire heat fluxes at the tank surface.Three tests were conducted with the 2300 L tanks filled to 15% capacity with propane. The tanks were positioned at three different distances from the wall fire resulting in measured average peak heat flux at the tank surfaces ranging between 24 and 43 kW m^?2. The data shows rapid rise in vapour space wall temperatures, significant temperature stratification in the vapour space, and moderate rate of pressure rise. These results provide excellent data for the validation of computer models used to predict the response of pressure vessels exposed to moderate heating from a remote fire.     

氯乙烯储罐的事故后果分析

氯乙烯具有毒性和易燃易爆性,如果泄漏至空气中,可能产生中毒或爆炸事故。笔者以某化工厂氯乙烯储罐为例,分析氯乙烯储罐可能发生的事故;对其主要事故危害,即中毒、蒸气云爆炸、扩展气体沸腾蒸气爆炸3种事故进行后果模型分析;计算出发生3种事故对人员伤亡和设备损坏造成的危害区域,并提出建议和对策。该研究结果可为同类企业进行安全管理提供科学依据和参考,有助于企业制定防范措施以及事故应急救援预案,从而减少人员伤亡及财产损失。     

LPG球罐BLEVE过程中超压与热耦合效应模拟研究

为评估LPG球罐发生BLEVE过程中超压与热耦合效应对化工企业抗爆控制室和避难所选址的影响,采用TNO多能法数学模型计算冲击波超压,采用多源数学模型计算火球热辐射。编写MATLAB计算程序,并应用ANSYS模拟二者破坏效应的耦合作用。LPG球罐发生BLEVE过程中,爆炸冲击波的传播速度、持续时间和火球的传播速度、持续时间不同,爆炸冲击波主要在燃料高速抛散的初期形成,之后基本与火球脱离。分别模拟计算冲击波超压和火球热辐射对抗爆控制室和避难所的影响,结果表明：抗爆控制室选址只需考虑爆炸冲击波的影响;避难所选址需要考虑冲击波超压和火球热辐射作用双重影响。在研究基础上提出,LPG球罐附近人员逃生的避难所应设置在球罐防火堤外紧邻防火堤处的地下,应具有抗震、防渗、防火、防中毒窒息等功能。人员应在BLEVE发生前进入避难所才能逃生。     

On the mechanism of a BLEVE occurrence due to fire engulfment of tanks with overheated liquids

The BLEVE (boiling liquid expanding vapor explosion) effect that involves the formation of a fireball occurs at the engulfment by fire of a tank with a highly flammable liquid or a liquid gas. Heating of the tank causes elevation of the liquid phase temperature and pressure inside the tank. A partial rupture of the dry tank walls is possible, with the formation of a rarefaction wave propagating into the liquid phase. An evaporation wave moves after the rarefaction wave and cause a rapid increase of pressure, exceeding the initial pressure before depressurization. Rapid violent destruction of the tank occurs. The mechanism of a BLEVE initiation is considered using Van der Waals isotherms. The following criterion for the possibility of a BLEVE was formulated. If the final state is located on an unstable part of the Van der Waals isotherm, a BLEVE takes place. Limiting values of the temperatures for overheating of certain highly flammable liquids and liquid gases (propane, n-butane, n-pentane, isopentane) were calculated using the proposed method, and were found to be in good agreement with experimental data available in the literature.