Fire and explosion risk assessment for large-scale oil export terminal

Now in Russian Federation and other countries large-scale oil terminals (volume of one tank exceeds 100 000 m³, total volume of tanks exceeds 300 000 m³) are designed and constructed. Therefore fire safety of such objects becomes a very important task, solution of which is hardly possible without detail fire risk assessment. This study is aimed to a solution of this problem. Potential, individual and social risks were calculated. The potential risk was defined as a frequency of occurrence of hazardous factors of fires and explosions in a given point of space (the so-called risk contours). The individual risk was defined as a frequency of injuring a given person by hazardous factors of fires and explosions. Time of presence of this person in hazardous zones (near the hazardous installation) is taken into account during calculations of the individual risk. Social risk was defined as a dependence of frequency of injuring a given number of people by hazardous factors of fires and explosions on this number. In practice the social risk is usually determined on injuring not less than 10 people.

The oil terminal under consideration includes the following main parts: crude oil storage consisting of three tanks of volume 100 000 m³ each, input crude oil pipeline of diameter 0.6 m, crude oil pumps, output crude oil pipeline of diameter 0.8 m, auxiliary buildings and facilities. The following main scenarios of tank fires have been considered: rim seal fire, pool fire on a surface of a floating roof, pool fire on a total cross-section surface of the tank, pool fire in a dyke, explosions in closed or semiclosed volumes. Fires and explosions in other parts of the terminal are also taken into account. Effects of escalation of accidents are considered.

Risk contours have been calculated both for the territory of the terminal and for the neighbouring space. The potential risk for the storage zone is near 10⁻⁴–10⁻⁵ year⁻¹, and at a distance 500 m from the terminal the potential risk values do not exceed 10⁻⁶ year⁻¹. The values of the individual risk for various categories of workers are in the range of 10⁻⁵–10⁻⁶ year⁻¹. Because of low number of the workers on the terminal and large distances to towns and villages the social risk value is negligible. These risk values are consistent with practice of the best oil companies, and fire hazard level of the terminal can be accepted as tolerable.     

Development of algorithms for predicting ignition probabilities and explosion frequencies

A project was performed for the Explosion Research Cooperative to develop algorithms for predicting the frequencies of explosions based on a variety of design, operating and environmental conditions. Algorithms were developed for estimating unit-based explosion frequencies, such as those reported in API Recommended Practice 752, but in more detail and covering a much broader range of chemical process types. The project also developed methods for predicting scenario-based explosion frequencies, using frequencies of initiating events and conditional probabilities of immediate ignition and delayed ignition resulting in explosion. The algorithms were based on a combination of published data and expert opinion.     

A new simple methodology for evaluation of explosion risk in underground coal mines

The key objective of this paper is the presentation of a new risk assessment tool for underground coal mines based on a simplified semi-quantitative estimation and assessment method.In order to determine the risk of explosion of any work process or activity in underground coal mines it is necessary to assess the risk. The proposed method is based on a Risk Index obtained as a product of three factors: frequency of each individual scenario P_ucm, associated severity consequences C_ucm and exposure time to explosive atmospheres E_ucm. The influence of exposure time is usually not taken into account up to now. Moreover, the exposure to explosive atmospheres may affect factors of hazardous event probability as much as its consequences. There are many definitions of exposure to explosive atmospheres but in the case of underground coal mines the exposure is defined as frequency risk of firedamp and coal dust. The risk estimation and risk assessment are based on the developed of a risk matrix.The proposed methodology allows not only the estimation of the explosion risk but also gives an approach to decide if the proposal investment is well-justified or not in order to improve safety.     

Does your facility have a dust problem: Methods for evaluating dust explosion hazards

The hazards of dust explosions prevailing in plants are dependent on a large variety of factors that include process parameters, such as pressure, temperature and flow characteristics, as well as equipment properties, such as geometry layout, the presence of moving elements, dust explosion characteristics and mitigating measures. A good dust explosion risk assessment is a thorough method involving the identification of all hazards, their probability of occurrence and the severity of potential consequences. The consequences of dust explosions are described as consequences for personnel and equipment, taking into account consequences of both primary and secondary events.While certain standards cover all the basic elements of explosion prevention and protection, systematic risk assessments and area classifications are obligatory in Europe, as required by EU ATEX and Seveso II directives. In the United States, NFPA 654 requires that the design of the fire and explosion safety provisions shall be based on a process hazard analysis of the facility, process, and the associated fire or explosion hazards. In this paper, we will demonstrate how applying such techniques as SCRAM (short-cut risk analysis method) can help identify potentially hazardous conditions and provide valuable assistance in reducing high-risk areas. The likelihood of a dust explosion is based on the ignition probability and the probability of flammable dust clouds arising. While all possible ignition sources are reviewed, the most important ones include open flames, mechanical sparks, hot surfaces, electric equipment, smoldering combustion (self-ignition) and electrostatic sparks and discharges. The probability of dust clouds arising is closely related to both process and dust dispersion properties.Factors determining the consequences of dust explosions include how frequently personnel are present, the equipment strength, implemented consequence-reducing measures and housekeeping, as risk assessment techniques demonstrate the importance of good housekeeping especially due to the enormous consequences of secondary dust explosions (despite their relatively low probability). The ignitibility and explosibility of the potential dust clouds also play a crucial role in determining the overall risk.Classes describe both the likelihood of dust explosions and their consequences, ranging from low probabilities and limited local damage, to high probability of occurrence and catastrophic damage. Acceptance criteria are determined based on the likelihood and consequence of the events. The risk assessment techniques also allow for choosing adequate risk reducing measures: both preventive and protective. Techniques for mitigating identified explosions risks include the following: bursting disks and quenching tubes, explosion suppression systems, explosion isolating systems, inerting techniques and temperature control. Advanced CFD tools (DESC) can be used to not only assess dust explosion hazards, but also provide valuable insight into protective measures, including suppression and venting.     

液化石油气站重大危险源的危险性评价

液化石油气站的罐区属于重大危险源,因其一旦发生泄漏,引起火灾、爆炸意外事故,造成的伤亡及财产损失巨大,评价其安全性,控制其危险,建立防范及应急救援系统是控制工业灾害的重大举措.笔者通过建立数学模型对液化石油气贮罐区的危险性进行定量化评价,得出罐区的危险等级以及其现实危险性,为控制重大危险源,提供了一种有效的方法.     

液化石油气罐区危险性的定量评价

液化石油气罐区的主要危险是贮罐区发生火灾、爆炸事故。运用数学模型对液化石油气贮罐的危险性进行定量化评价，估算其爆炸事故的严重程度、波及范围、影响程度等     

Explosion pressure prediction via polynomial mathematical correlation based on advanced CFD Modelling

Computational Fluid Dynamics CFD can be used as a powerful tool supporting engineers throughout the steps of the design. The combination of CFD with response surface methodology can play an important role in such cases. During the conceptual engineering design phase, a quick response is always a matter of urgency. During this phase even a sketch of the geometrical model is rare. Therefore, the utilisation of typical response surface developed for congested and confined environment rather than CFD can be an important tool to help the decision making process, when the geometrical model is not available, provided that similarities can be considered when taking into account the characteristic of the geometry in which the response surface was developed. The present work investigates how three different types of response surfaces behave when predicting overpressure in accidental scenarios based on CFD input. First order, partial second order and complete second order polynomial expressions are investigated. The predicted results are compared with CFD findings for a classical offshore experiment conducted by British Gas on behalf of Mobil and good agreement is observed for higher order response surfaces. The higher order response surface calculations are also compared with CFD calculations for a typical offshore module and good agreement is also observed.     

Computer simulation of shock waves transmission in obstructed terrains

Generation and transmission of blast waves in real terrains is of major importance for risk analysis procedures involving accidental explosion scenarios. The problem arises from the impact of overpressure wave on people and structures that may be lethal or catastrophic under certain conditions. In this paper, a CFD simulation of shock wave propagation in obstructed terrain is attempted. Overpressure histories as well as a series of critical parameters, namely the positive and negative peak overpressure, the arrival time, and the positive and negative phase duration at specific points within the domain were obtained during the simulation. Their comparison with experimental measurements from field-scale high explosive blast tests performed by HSE showed a reasonably good agreement indicating that CFD computer programs provide reliable tools for estimating explosive shocks in complex terrains.     

密闭爆炸容器实验研究及数值模拟

实验研究了三种结构的爆炸容器在爆炸载荷下的响应情况；并通过二维多流体欧拉程序对二维爆炸场进行了数值模拟．在这个基础上用ＮＩＫＥ－２Ｄ对壳体的动态响应进行数值模拟。     

粉尘爆炸技术的最新发展

系统论述了爆炸防护技术的最新发展，为了选择最佳防护措施必须恰当鉴定和评估，包括材料的性质。借助一些经验公式，可估算温度对各种材料操作参数的影响。用情化法不仅可防止可爆混合物的形成还可防止其着火。对设备的“结构防爆”措施，近年来已制造出买用的容器。可以确信，工业爆炸防护领域必将拥有足够的技术以有效地战胜爆炸危险。     

Modeling of BP Texas City refinery incident

This paper presents detailed modeling results of the BP Texas City refinery incident. Three different approaches and explosion modeling tools were used to study the event. The results predicted by all three approaches are similar and all approaches identified a hazard potential comparable to what was witnessed on March 23, 2005. This confirms that quantitative risk assessment (QRA) has the ability to model a realistic scenario, and is therefore useful in safety measure design and emergency preparedness decision making to improve overall safety performance. Had QRA been conducted during a management of change (MOC) decision-making process, personnel trailers likely would not have been sited in such close proximity to the process units. The resulting severe consequences would then not have occurred. This work also aims to emphasize the importance of QRA in process safety management.

The paper presents the authors’ perception of the sequence of events involved in the incident based on the published literature available at the time of writing. It also assesses potential consequences for the perceived sequence of events using a variety of consequence assessment tools. In doing so, the analysis illustrates how this incident could have been prevented in spite of many operational difficulties. The observations and commentary presented in this paper are intended solely for the purpose of process safety enhancement on the basis of the lessons learned. BP has published its own detailed report; the incident is also the subject of a recent investigation by the US Chemical Safety and Hazard Investigation Board, with the CSB's final report being available at http://www.csb.gov/index.cfm?folder=completed_investigations&page=info&INV_ID=52 (as of April 2007).     

论特种设备事故(突发事件)的应急响应与科学处置

为满足基于大数据的特种设备事故推演和预防技术及平台的研发与应用,本文研究了特种设备事故(突发事件)应急处置现状和存在的问题,归纳总结出特种设备安全共性风险,设计和完善了事故响应、控制、预防等应急处置方案与应急救援体系,并进行了实例验证.同时,本文还对在应急处置平台系统上的部署和应用提出了期望.