基于改进贝叶斯网络的加油站火灾爆炸分析

为了找出导致加油站发生火灾爆炸事故的基本事件及其可能性大小,以加油站火灾爆炸故障树为基础建立相应的贝叶斯网络风险模型。在FTA向BN转化算法的基础上对条件概率做出了修正。利用GeNIe软件计算加油站火灾爆炸事故基事件的后验概率,同时进行灵敏度和影响力分析。最后通过实例分析,找出了导致某加油站发生火灾爆炸事故危险性最大的因素集为:加油站接打手机、机械碰撞、给塑料容器加油、加油冒油、油枪渗漏等。结果表明,注重基事件的多态性和事件间逻辑关系合理性的新模型,能推算出更准确的基事件概率分布,同时可以找出导致事故发生的最有可能途径,为加油站事故预防,系统改进提供较为合理性建议。     

Risk assessment of an oxygen-enhanced combustor using a structural model based on the FMEA and fuzzy fault tree

The oxygen-enhanced combustor has the advantages of high burning efficiency and low emissions. However, it should not be promoted for industrial use until its reliability and safety have been fully recognized. A new methodology is proposed to assess the risk of an oxygen-enhanced combustor using a structural model based on the FMEA and fuzzy fault tree. In addition, it is applied to a selected pilot semi-industrial combustor. To identify the hazard source comprehensively, the pilot is divided into four subsystems: the combustor subsystem, feed subsystem, ignition subsystem and exhaust subsystem. According to the operational parameters of flow (flow rate, temperature and pressure) and the component functions in different subsystems, the cause and effect matrix can be built using the structural model, and the relationship between the operational parameters and the effects of the change for the operational parameters on the system can be presented. Based on the results of cause and effect matrix, the FMEA can be built to describe the failed models and accident scenarios of the pilot. The main accident forms include leakage, injury, fire and explosion. Accordingly, with the severity and probability analysis of different accident forms, the fire and explosion accidents should be further accessed quantitatively using the fuzzy fault tree analysis. The fault trees can be obtained in accordance with the FMEA, and the qualitative assessments of the basic events can be collected by using expert scoring. A hybrid approach for the fuzzy set theory and weight analysis is investigated to quantify the occurrence probability of basic events. Then, the importance analysis of the fault trees, including the hazard importance of basic events and the cut set importance, is performed to help determine the weak links of the fire and explosion trees. Finally, some of the most effective measures are presented to improve the reliability and safety of the combustion system.     

煤矿本质安全化管理体系建立及其应用的探讨

运用安全系统工程中的事故树理论,以瓦斯爆炸事故为例分析了煤矿中的7类主要事故,并得出相应的事故树。通过对事故树的定性分析,得出事故树的最小径集和基本事件重要度排序。进而可预测基本事件的发生所能够导致的结果,可根据各基本事件的重要度排序,确定避免发生事故应采取的基本措施,并建立了煤矿本质安全化管理体系。设计出煤矿本质安全化管理体系的软件,并以瓦斯爆炸事故为例,分析了该管理体系在实际中的应用效果。     

Evaluation of the Risk OMT model for maintenance work on major offshore process equipment

Operational safety is receiving more and more attention in the Norwegian offshore industry. Almost two thirds of all leaks on offshore installations in the period 2001–2005, according to the Risk Level Project by the Petroleum Safety Authority in Norway, resulted from manual operations and interventions, as well as shut-down and start-up. The intention with the Risk OMT (risk modelling – integration of organisational, human and technical factors) program has been to develop more representative models for calculation of leak frequencies as a function of the volume of manual operations and interventions. In the Risk OMT project a generic risk model has been developed and is adapted to use for specific failure scenarios. The model considers the operational barriers in event trees and fault trees, as well as risk influencing factors that determine the basic event probabilities in the fault trees. The full model, which applies Bayesian belief networks, is presented more thoroughly in a separate paper. This paper presents the evaluation of the model. The model has been evaluated through some case studies, and one important aspect is the evaluation of the importance of each risk influencing factor. In addition some risk-reducing measures have been proposed, and the paper presents how the effect of these measures has been evaluated by using the model. Finally, possible applications and recommendations for further work are discussed.     

基于BN的锅炉超压爆炸事故原因推理与故障诊断

分析了锅炉爆炸的原因,讨论了事故树与贝叶斯网络的特点,编制了以"锅炉超压爆炸事故"为顶事件的事故树,将其转化为锅炉超压爆炸事故贝叶斯网络拓扑结构,利用贝叶斯网络的技术优势,针对锅炉超压爆炸事故贝叶斯网络拓扑结构分别进行了原因推理与诊断推理。实例应用表明,在原因推理中,根节点V_1(压力上升)发生时锅炉超压爆炸事故发生的可能性最高;在诊断推理中,当锅炉超压爆炸事故发生时,根节点V_1(压力上升)一定发生,其次为V_4(定压不准),V_(11)(未装疏水管)发生的可能性最小,为企业进行锅炉超压爆炸事故预测与故障诊断提供了理论依据。     

石化装置火灾爆炸贝叶斯网络与防护层集成分析

复杂的石油化工装置在运转过程中存在诸多不确定因素,易发生火灾、爆炸等重大事故,给安全生产带来极大威胁。考虑到传统的系统安全分析方法在风险评估中存在一定局限性,引入贝叶斯网络与防护层集成分析模型。应用GeNIe软件将系统故障树转成贝叶斯网络,根据贝叶斯双向推理进行故障预测和诊断,快速识别系统薄弱环节并确定为风险贝叶斯故障节点,结合防护层分析提出相应的独立防护层,确定剩余风险水平。实例应用表明,所构建的贝叶斯网络与防护层集成分析模型对复杂系统进行风险评估是可行的,较传统的事件树、故障树分析方法更加科学、合理。     

Operational risk assessment: A case of the Bhopal disaster

Accidental releases of hazardous chemicals from process facilities can cause catastrophic consequences. The Bhopal disaster resulting from a combination of inherently unsafe designs and poorly managed operations is a well-known case. Effective risk modeling approaches that provide early warnings are helpful to prevent and control such rare but catastrophic events. Probability estimation of these events is a constant challenge due to the scarcity of directly relevant data. Therefore, precursor-based methods that adopt the Bayesian theorem to update prior judgments on event probabilities using empirical data have been proposed. The updated probabilities are then integrated with consequences of varying severity to produce the risk profile.This paper proposes an operational risk assessment framework, in which a precursor-based Bayesian network approach is used for probability estimation, and loss functions are applied for consequence assessment. The estimated risk profile can be updated continuously given real-time operational data. As process facilities operate, this method integrates a failure-updating mechanism with potential consequences to generate a real-time operational risk profile. The real time risk profile is valuable in activating accident prevention and control strategies. The approach is applied to the Bhopal accident to demonstrate its applicability and effectiveness.     

Consequence risk analysis using operating procedure event trees and dynamic simulation

Faults due to human errors cost the petrochemical industry billions of dollars every year and can have adverse environmental consequences. Unquantified human error probabilities exist during process state transitions performed each day by process operators using standard operating procedures. Managing the risks associated with operating procedures is an essential part of managing the overall safety risk. Additional operator training and safety education cannot eliminate all such faults due to human errors; therefore, we propose an operating procedure event tree (OPET) like analysis with branches and events specifically designed to perform risk analysis on operating procedures. The OPET method adapts event trees to analyze the risk due to human error while performing operating procedures. We consider human error scenarios during the procedure and determine the likely consequences by applying dynamic simulation. The modified event tree provides an estimate of the error frequencies.Operating procedure steps were developed, and potential operator faults were determined for two typical equipment switching procedures found in chemical plant operations. Then, dynamic simulation using Aspen HYSYS software was applied to determine the overpressure related consequences of each fault. Finally, the error frequencies resulting from those scenarios were analyzed using operating procedure event trees. We found that a typical ethylene plant gas header would overpressure with 0.6% frequency per manual dryer switch. Since dryer switches occur from every few days up to once per shift, these results suggest that dryer switching should be automated to ensure safe and environmentally friendly operation. Process dryer switching performed manually by operators opening and closing gate valves can be automated with control valves and a distributed control system. A sample distillation column was found to overpressure with 0.85% frequency per manual reflux pump switch.     

聚乙烯醇罐区火灾爆炸事故树分析

通过现场的调研与事故树分析相结合的手段对某厂聚乙烯醇车间聚合罐区火灾爆炸事故的危险因素进行了识别与分析.以该罐区可能发生的火灾爆炸事故作为顶上事件,对可能引发顶上事件的21个基本事件及一个条件事件构建事故树,利用最小割集、最小径集及结构重要性计算手段进行事故风险程度分析,从而确定醋酸乙烯暴聚是聚合罐区的首要危险源,而促发醋酸乙烯暴聚的物料长时间停留、气相氧含量过高、温度控制失效、阻聚剂含量不足等四个基本事件是导致聚合罐区火灾爆炸事故的最危险因素.本文对以上聚合罐区发生火灾爆炸事故的风险因素进行详细定性分析,并在此基础上有针对性的提出了相应的安全预防控制措施.同时,该聚合罐区的事故树分析结论也可以为同类别化工单位罐区的日常运行、设计改造、维护保养等工作提供理论依据.     

Hydrocarbon releases on oil and gas production platforms: Release scenarios and safety barriers

The main objective of this paper is to present and discuss a set of scenarios that may lead to hydrocarbon releases on offshore oil and gas production platforms. Each release scenario is described by an initiating event (i.e., a deviation), the barrier functions introduced to prevent the initiating event from developing into a release, and how the barrier functions are implemented in terms of barrier systems. Both technical and human/operational safety barriers are considered. The initiating events are divided into five main categories: (1) human and operational errors, (2) technical failures, (3) process upsets, (4) external events or loads, and (5) latent failures from design. The release scenarios may be used as basis for analyses of: (a) the performance of safety barriers introduced to prevent hydrocarbon releases on specific platforms, (b) the platform specific hydrocarbon release frequencies in future quantitative risk analyses, (c) the effect on the total hydrocarbon release frequency of the safety barriers and risk reducing measures (or risk increasing changes).     

Risk assessment and risk reduction of an acrylonitrile production plant

Reducing accident occurrence in petrochemical plants is crucial, thus appropriately allocating management resources to safety investment is a vital issue for corporate management as international competition intensifies. Understanding the priority of safety investment in a rational way helps achieve this objective.In this study, we targeted an acrylonitrile plant. First, Dow Chemical's Fire and Explosion Index (F&EI) identified the reaction process as having the greatest physical risk. We evaluated the severity of accidents in the reaction process using the Process Safety Metrics advocated by the Center for Chemical Process Safety (CCPS); however, this index does not express damages a company actually experience. To solve this problem, we proposed a new metric that adds indirect cost to CCPS metrics. We adopted fault tree analysis (FTA) as a risk assessment method. In identifying top events and basic events, we attempted to improve the completeness of risk identification by considering accidents from the past, actual plant operation and equipment characteristics, natural disasters, and cyber-attacks and terrorist attacks. Consequently, we identified the top events with high priority in handling because of serious accidents as fire/explosion outside the reactor, fire/explosion inside the reactor, and reactor destruction. The new CCPS evaluation index proposed in this study found that fire and explosion outside the reactor has the highest severity. We considered the creation of the fault tree (FT) diagram of the top event, estimating the occurrence probability, and identifying the risk reduction part and capital investment aimed at risk reduction. As an economically feasible selection method for risk reduction investment, using the difference in loss amounts before and after safety investments indicated investment priority.     

基于UHBs的输气管道高后果区泄漏燃爆事故分析

为探究输气管道高后果区中人的不安全行为（Unsafe Human Behaviors,UHBs）对输气管道泄漏燃爆事故发生的影响,结合模糊Bow-tie模型和贝叶斯网络对输气管道泄漏燃爆事故进行分析。构建基于T-S模糊故障树的输气管道泄漏燃爆模糊Bow-tie模型,并转化为贝叶斯网络;从人的不安全行为发生的可能性出发,将不同等级高后果区划分为不同等级人口敏感区;利用专家经验评判法得到不同等级人口敏感区基本事件的先验概率和中间事件的条件概率表;运用贝叶斯网络双向推理算法求解模糊Bow-tie模型。结果表明:随着地区人口敏感等级的提高,输气管道泄漏燃爆事故发生的概率随之增大,发现导致输气管道失效泄漏事故发生的最主要原因为施工破坏,失效原因与EGIG分析的结果基本相符,验证该方法在高后果区输气管道泄漏燃爆事故分析上的可行性,可为输气管道高后果区的安全管理提供决策依据。     

煤矿瓦斯爆炸事故隐患及风险的表征方法

为治理煤矿瓦斯爆炸事故隐患,管控其风险大小,基于证据对瓦斯爆炸事故隐患进行了系统辨识,利用逻辑图分析了隐患之间的耦合关系和风险演化路径;从事件发生的可能性、事件自身的严重性以及受体的暴露程度3个方面对瓦斯爆炸风险进行表征,并提出三维风险矩阵对事故风险进行分级评价。该方法可以为瓦斯爆炸事故隐患辨识、风险分析、风险评价以及设计事故预防措施提供借鉴。     

Dynamic accident modeling for high-sulfur natural gas gathering station

Dynamic accident modeling for a gas gathering station is implemented to prevent high-sulfur natural gas leakage and develop equipment inspection strategy. The progress of abnormal event occurring in the gas gathering station is modeled by the combination of fault tree and event sequence diagram, based on accident causal chain theory, i.e. the progress is depicted as sequential failure of safety barriers, then, the occurrence probability of the consequence of abnormal event is predicted. Consequences of abnormal events are divided into accidents and accident precursors which include incidents, near misses and so on. The Bayesian theory updates failure probability of safety barrier when a new observation (i.e. accident precursors or accidents data) arrives. Bayesian network then correspondingly updates failure probabilities of basic events of the safety barriers with the ability of abductive reasoning. Consequence occurrence probability is also updated. The results show that occurrence probability trend of different consequences and failure probability trend of safety barriers and basic events of the safety barriers can be obtained using this method. In addition, the critical basic events which play an important role in accidents occurrence are also identified. All of these provide useful information for the maintenance and inspection of the gas gathering station.     

基于贝叶斯网络的危化品爆炸事故电力系统风险评估模型

为提高危化品爆炸事故电力应急预警的准确性,建立基于贝叶斯网络的危化品爆炸事故电力系统风险评估模型.基于危化品爆炸事故电力应急典型情景分析,建立综合考虑突发事件、承灾载体和应急管理等风险因素的贝叶斯网络结构.应用概率刻画风险因素信息的不确定性及其相互影响,定量分析事件后果.结合一般条件和典型情景等的应用实例,分析评价方法...     

Generic event trees and probabilities for the release of different types of hazardous materials

To simplify quantitative risk analysis, the initiating events leading to loss of containment are normally described using generic hypotheses. For example, the following hypothesis is applied to the loss of containment from a storage tank: instantaneous release of the complete inventory, continuous release of the complete inventory in 10 min, and continuous release from a hole with a diameter of 10 mm. Once the initiating events have been specified, the corresponding event trees must be drawn to establish the sequences from each initiating event to the diverse final outcomes or accident scenarios, which will depend on the properties of the released material or on other specific factors. In this paper we propose, in a systematic way, a set of short generic event trees for the main loss of containment scenarios involving different types of hazardous materials. Even though most of them have been taken from the literature (BEVI Reference Manual), we have modified some of them, added the corresponding intermediate probabilities (immediate ignition, delayed ignition, flame front acceleration, etc.) obtained from a literature review and expert judgment, and associated the use of each event tree to the hazardous properties of the material (flammability, volatility and toxicity) and to its category according to EC labeling directives.     

基于FMECA与模糊FTA的余热锅炉安全分析

为了保证余热锅炉安全运行,预防爆炸事故发生,利用FMECA方法和模糊FTA方法,研究余热锅炉事故致因。通过对余热锅炉潜在危险因素的分析辨别,探讨设备故障类型、原因及相应处理方法,引入模糊FTA对余热锅炉爆炸事故定性和定量分析,进而构建了基于FMECA与模糊FTA的余热锅炉安全分析框架,并计算得出事故发生的模糊概率以及对基本事件的敏感性分析。研究表明,余热锅炉系统的可靠度大约为96.92%,未按规定排污,报警器失灵,安全阀压力连接管堵塞及除氧器不合格事件对顶事件发生概率的影响最大,从而为该系统的安全决策提供支持。     

Dynamic risk assessment for underground gas storage facilities based on Bayesian network

Loss of the underground gas storage process can have significant effects, and risk analysis is critical for maintaining the integrity of the underground gas storage process and reducing potential accidents. This paper focuses on the dynamic risk assessment method for the underground gas storage process. First, the underground gas storage process data is combined to create a database, and the fault tree of the underground gas storage facility is built by identifying the risk factors of the underground gas storage facility and mapping them into a Bayesian network. To eliminate the subjectivity in the process of determining the failure probability level of basic events, fuzzy numbers are introduced to determine the prior probability of the Bayesian network. Then, causal and diagnostic reasoning is performed on the Bayesian network to determine the failure level of the underground gas storage facilities. Based on the rate of change of prior and posterior probabilities, sensitivity and impact analysis are combined to determine the significant risk factors and possible failure paths. In addition, the time factor is introduced to build a dynamic Bayesian network to perform dynamic assessment and analysis of underground gas storage facilities. Finally, the dynamic risk assessment method is applied to underground gas storage facilities in depleted oil and gas reservoirs. A dynamic risk evaluation model for underground gas storage facilities is built to simulate and validate the dynamic risk evaluation method based on the Bayesian network. The results show that the proposed method has practical value for improving underground gas storage process safety.     

Analysis and assessment of a critical event during an underground coal gasification experiment

The main goal of the study presented in this paper was to analyse the mechanisms affecting an Underground Coal Gasification (UCG) process and to identify possible deviations of the system from normal work to limit, or even avoid, losses. The UCG process is one of the most innovative technologies connected with the exploitation of coal deposits that are currently being tested and developed all around the world. It allows the conversion of a coal seam into gas under in situ conditions of high temperature with the use of gasifying agents such as air, oxygen, steam or with a mixture of them.The paper presents the results of the analysis and assessment of a critical event during the process: a dangerous gas accumulation that occurred during an underground coal gasification experiment in the Experimental Mine “Barbara” of the Central Mining Institute (Poland). The UCG experiment using the shaft method is described, together with its monitoring system and the problems that appeared during the process. The application of the Fault Tree Methodology allowed the establishment of the main factors that may lead to the explosion and to present possible scenarios of its occurrence.Moreover, calculations were carried out to evaluate the risk level of explosion for the gas mixture and the minimum level of oxygen in the mixture that is necessary to initiate an explosion. These calculations were based on a modification of the formula proposed by Le Chatelier. During the course of the underground experiment, original information of the process behaviour has been acquired that can be used in the preparation of other UCG experiments in operational mines to guarantee the safety and the stability of the process.