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.     

多传感器耦合区域火灾报警技术研究

早期预警与低误报率一直是建筑火灾探测面临的挑战与难题。已有研究多针对特殊场所特定燃烧产物或多种传感器耦合,普适性不强,探测设备成本高,无法大规模应用。通过将火灾烟气蔓延规律与探测器信号时空分布融合,在不增加探测器数量和分布的情况下,提出了一种基于建筑结构微元的多传感器耦合区域火灾报警模型。对典型火灾场景的烟气蔓延情况进行了模拟分析,狭长结构中探测器信号强度变化具有一定的规律性。应用区域火灾报警模型后,报警时间较传统模式提前了14.7%,基本杜绝了单个探测器误报引发建筑物火灾报警的问题。结果表明:多传感器耦合探测模式显著缩短了火灾报警时间,降低了火灾探测误报率,实现了火灾的早期准确识别与预警。     

Measuring and analyzing adaptive capacity at management levels of resilient systems

Resilience engineering (RE) is capable of handling disruptive events and controlling their consequences in process industries such as petrochemical plants. This study aims at analyzing the level of adaptive capacity and identifying effective factors on developing adaptive capacity in the organizational structure of process industries. The data of this study were obtained through direct observation and a structured questionnaire in a petrochemical plant. Managers at all levels participated in the survey. Data envelopment analysis (DEA), which is a mathematical approach, was used to compute and analyze the role of the factors contributing to adaptive capacity. The results indicated that reporting safety issues played a central role in enhancing adaptive capacity at all management levels. Both middle management and low-level management emphasized the importance of management commitment, whereas top-level management considered flexibility as a vital factor in managing disruptions and reducing accidents. The findings of this study could be useful for managers and other decision-makers to improve safety in process industries.     

Guidelines for life extension process management in oil and gas facilities

Facilities life extension has caught the attention among the capital-intensive industries, like oil and gas. By extending the life cycle of the industrial assets, a wide range of benefits is obtained, comparing with other life ending management strategies. This article first contextualizes the implementation of the life extension concept in the oil and gas industry, showing global data about life extension. Despite the importance of the ageing process, due to its great economic impact and the risk it poses to the production sector, regulatory entities, even in countries more advanced in that sector or that have already experienced the extension process, developed only superficial material about the topic without defining a structured methodology for the assessment of the possibility of useful life extension. The available references do not allow a comprehensive analysis of that possibility, which highlights the importance the methodology proposed. Thus, this article proposes a guideline for the life extension process management, strengthening a framework containing the main evaluation stages, aiming to facilitate the analysis of issues related to ageing and to support the decision-making process. Lastly, real case studies regarding current life extension processes submitted to the Brazilian regulatory body were evaluated against the proposed framework stages, evidencing their lack of necessary details to support the decision-making. Upon the realization that the real cases identified do not allow for the assessment of the contribution and adequacy of the proposed framework in its entirety, the same was also applied to a hypothetical case. The latter was developed based on facts reported by a major operator in Brazil. The result was the determination that the use of the proposed methodology transformed the assessment of the possibility of life extension into a systematic and transparent process, leading to easier and better-founded decision-making procedures, and improving the management of the asset during its extended life.     

Systematic incorporation of inherent safety in hazardous chemicals supply chain optimization

Increasing globalization has made many chemical supply chains large, interdependent and complex. Process incidents often affect the reliability of a supply chain and can cause large disruptions at different segments of the industry. We propose an optimization-based framework that systematically takes into account the trade-offs between process safety and supply chain economics for decision-making. We quantify the hazard at various supply chain echelons in the form of a safety index that takes both fire and toxic hazards into account. A mixed-integer nonlinear programming (MINLP)-based model is developed to either maximize profit for specified hazard limits, or to minimize hazard in a supply chain with multiple production plants, technological options, warehouses and distribution nodes. The MINLP model is used to generate trade-off optimal solutions for various toxic and fire hazard limits. The framework is demonstrated by applying it to an end-to-end ammonia supply chain case study which resulted in several non-intuitive observations regarding hazardous supply chain design and optimization.     

宁夏能源结构的低碳优化研究

宁夏的经济结构具有显著的高碳特征,煤炭与电力行业占全区工业产值的比重约1／2,工业产值又占据宁夏GDP的半壁江山。低碳时代的到来不可逆转,减碳是对宁夏经济的重大考验与挑战。采用灰色关联分析法对宁夏各行业与碳排放的关联度进行分析,并结合各相关产业区域专业化系数分析,提出宁夏产业结构升级和能源结构优化的建议。     

基于偏离份额法的我国区域科技经费投入“来源—执行”结构分析

科技经费投入既应注重量的提升,又应关注科技经费投入结构的优化,在加大科技经费投入的同时积极优化投入结构是提高科技资源使用效率的途径。采用偏离份额分析法,从科技经费投入的＂来源—执行＂结构角度测算了我国八大经济区的科技经费投入结构,并从科技经费投入的增长效应、结构效应、竞争力三个方面进行分析,反映出区域科技经费投入发展的速度、动力机制和制度特征。     

山东省经济结构的失衡水平:测度和比较

山东省是中国经济发展最快的省区之一,但随着经济增长的不断推进所积累的矛盾和失衡水平也逐渐提高,经济发展的可持续性日趋降低。为考察山东省经济发展的现状,明确山东省经济结构中存在的问题,该文拟根据文献[1]的方法,构建省域经济结构失衡程度指标体系。考虑到省域经济的特殊性,确定了包括产业结构、投资消费结构、金融结构、省内经济结构和国际收支结构5大类共17个指标作为基本指标体系,对近10年以来山东省经济结构失衡程度进行了测试,并且利用相同的指标体系对广东、江苏、浙江等东部代表性省区以及全国的整体结构失衡水平进行了测度和比较分析,明确了山东省经济结构失衡的绝对水平和相对水平。结果表明:山东省经济结构失衡现象较为突出,经济发展的可持续性日趋降低。本文建议山东省加快第三产业发展,理顺投资与消费的关系,提高国民经济中消费所占比重,平衡省内各市际间经济发展水平才能真正缓解经济结构失衡状况,增强可持续发展的动力。     

麻栎混交林空间结构与物种多样性研究

林分空间结构是指林木在林地上的分布格局,以及林木之间树种、大小、分布等空间关系。林分空间结构决定了树木之间的竞争势及其空间生态位,在很大程度上决定了林分的稳定性、发展的可能性和经营空间的大小。研究目的在于揭示麻栎混交林林分空间结构与物种多样性特征,为林分空间结构调整和物种多样性保护提供理论依据。利用混交度、大小比数和角尺度3种空间结构参数,以及丰富度指数、Shannon-Wiener指数、Pielou指数等物种多样性数量指标,分析了青阳县麻栎混交林林分空间结构以及群落物种多样性特征。结果表明:乔木层优势树种麻栎多为中度以下混交,小叶栎和枫香多为强度和极强度混交;麻栎在空间大小和重要值对比上占有优势地位,小叶栎处于次要地位,枫香处于劣势地位为受压树种;从林分平面布局上看,该林分空间分布多为随机分布。分层物种丰富度和Shannon-Wiener指数依次是乔木层<草(含藤)本层<灌木层;而均匀度Pielou指数则是乔木层<灌木层<草(含藤)本层;生态优势度Simpson指数为乔木层>草本层>灌木层;灌木层有17科18属21种植物,淡竹占优势地位,野茉莉、山胡椒等占亚优势地位;草本层有10科12属13种植物,禾叶土麦...     

Can level of safety climate predict level of orientation toward safety in a decision making task?

Establishing the relationship between level of safety climate and safety performance is a current challenge. This work examines the relationship between level of safety climate and orientation toward safety in the decision making process and choice. Alternatively, this work seeks to answer the question of whether level of safety climate can predict safety-oriented decision making. A generalized safety climate questionnaire and a decision making simulation are utilized to examine this relationship. The results indicate that level of safety climate is not a significant predictor of the decision process; however, it was found to be a significant predictor of the selection of safer choices.