A framework to estimate the risk-based shutdown interval for a processing plant

Petrochemical plants and refineries consist of hundreds of pieces of complex equipment and machinery that run under rigorous operating conditions and are subjected to deterioration over time due to aging, wear, corrosion, erosion, fatigue and other reasons. These devices operate under extreme operating pressures and temperatures, and any failure may result in huge financial consequences for the operating company. To minimize the risk and to maintain operational reliability and availability, companies adopt various maintenance strategies. Shutdown or turnaround maintenance is one such strategy. In general, shutdown for inspection and maintenance is based on the original equipment manufacturer's (OEM) suggested recommended periods. However, this may not be the most optimum strategy given that operating conditions may vary significantly from company to company.The framework proposed in this work estimates the risk-based shutdown interval for inspection and maintenance. It provides a tool for maintenance planning and decision making by considering the probability of the equipment or system for failure and the likely consequences that may follow. The novel risk-based approach is compared with the conventional fixed interval approach. This former approach, characterized as it is by optimized inspection, maintenance and risk management, leads to extended intervals between shutdowns. The result is the increase in production and the consequent income of millions of dollars.The proposed framework is a cost effective way to minimize the overall financial risk for asset inspection and maintenance while fulfilling safety and availability requirements.     

木制家具生产行业的职业危害与个体防护

通过对木制家具生产工艺流程及加工过程的调研分析,归纳出木粉尘、噪声、有机挥发物、机械伤害等10种主要危害因素,将各种危害因素对安全健康的影响和致病形式进行总结,并对木制家具生产企业进行现场调查。指出企业在职业危害防护措施方面的欠缺与不足,同时对木制家具生产行业职业危害的防护措施、个体防护装备的选用以及防护装备使用中的注意事项进行说明。研究认为,木制家具生产行业中危害因素多且危害程度严重,安监部门应加强对企业的监督管理,企业应为职工提供有效防护措施和个体防护装备。     

基于遗传算法的PLS分析在QSAR研究中的应用

将遗传算法和偏最小二乘法结合应用于定量结构活性关系研究中 ,进行变量选择和建立最终模型 .以较少的变量个数包含较多的变量信息 ,且变量间没有线性相关问题 ,因而得到较好的 QSAR模型 .将这种方法应用于氯代酚和单取代苯 2种系列化合物 ,可以得到几种常规多元回归分析方法不能得到的质量较高的 QSAR模型 .     

湖泊水生植被恢复物种选择及群落配置分析

介绍了水生植物恢复的常用物种及生活型 ,并从群落配置的物种数 ,群落的空间配置及节律匹配等方面对水生植物群落的优化配置进行了分析和研究 ,结果表明 :1 )在水生植物群落恢复实践中 ,无论从经济角度考虑 ,还是从可操作性出发 ,均应优先考虑选择少量先锋物种 ,先恢复生态系统的基本结构和功能 ,随着生境条件的不断改善 ,逐步栽种新的物种 ,增加物种的多样性 ;2 )根据湖相生态系列在空间生境梯度上的变化 ,按水生植物生活型配置群落是群落配置的基本出发点 ;3)应根据水生植物的季节差异合理配置群落 ,使植物种群在生长期上密切衔接 ,形成常绿人工水生植被 ,这样在冬季也能较好地发挥对湖泊的净化功能     

ICZS-活性污泥新技术处理CTMP废水的研究

探讨了ＩＣＺｓ－活性污泥生物系统在控制污泥膨胀过程中的影响因素及其处理效果。３个月的实验结果表明：当ＩＣＺｓ预反应段的条件控制在溶解氧小于０．０６ｍｇ／Ｌ,ｐＨ为７－７．６时,该生物系统能够有效控制污泥膨胀。ＩＣＺｓ－活性污泥生物系统具有高效去除污染物的能力。ＢＯＤ５,ＣＯＤ和ＴＳＳ总去除率的平均值分别高于９７％,８０％及９０％,其中仅ＩＣＺｓ段在预处理时间为２０ｍｉｎ时就能去除４９．０％－６２．     

生物滴滤池法处理有机废气甲苯工艺填料的选择

生物滴滤池法处理挥发性有机污染物的研究是世界工业废气净化的前沿热点之一，本研究比较了阶梯环，聚乙烯小球，煤炭渣和某种活性炭附着纤维作为滴滤池中生物附着载体性能的优劣，结果表明，活性炭附着纤维填料系统具有较好的有机污染物去除能力。     

壬基酚对Americamysis bahia种群安全暴露基准浓度的确定

采用正态分布累积函数和幂函数,分别建立了壬基酚(NP)对Americamysis bahia多代种群暴露影响的浓度-种群周限增长率(λ)和浓度-种群内禀增长率(r)曲线,根据各自拟合的模型选择基准(MSC)值选择幂函数浓度-r曲线来估算种群安全暴露浓度.使用浓度-r曲线的浓度(r=0)的95%置信区间下限作为种群水平上的安全暴露基准浓度,确定了NP对Americamysis bahia种群多代安全暴露浓度(1.87μg·l-1).这个基准浓度要低于多代暴露实验所获得的NP的个体水平上的慢性繁殖毒性的安全浓度(12μg·l-1).     

城市生活垃圾卫生填埋场选址研究

结合城市垃圾卫生填埋场的实例和工程实践的经验,分别从城市总体规划、场址自然地理条件、填埋场的库容、场地外部建设条件和满足社会法律的要求等几个方面对填埋场的场址的选择做了详细的分析和探讨。     

燃煤电厂除尘器的应用和选择研究

对目前我国燃煤电厂中使用较多的几种除尘器——电除尘器、袋式除尘器及电袋复合除尘器的原理、发展及应用进行了介绍和阐述,并结合几种除尘器的特点和国内外运行实例,就我国燃煤电厂除尘器的选择提出了建议。     

Treating design uncertainty in the application of Eco-indicator 99 with Monte Carlo simulation and fuzzy intervals

In incremental eco-design improvements, design engineers attempt to modify an existing product via some eco-design measures to reduce the product’s environmental impacts (e.g. reduction of material usage and energy consumption). In this process, several design concepts can be proposed, and concept selection is required to allocate resources sensibly to promising design concepts only. In this context, the research purpose is to estimate the environmental impacts of each concept given the uncertainty of design information. In the proposed methodology, the fuzzy interval arithmetic is used to specify and propagate imprecise design information. Then, the centroid concept is applied to model different views of imprecision (i.e. pessimistic, balanced and optimistic) associated with fuzzy impact assessment. Accordingly, a decision scheme is developed to support concept selection and suggest the potential areas for further eco-design improvements. A coffee maker is used as an example to demonstrate the proposed methodology. Also, the Monte Carlo Simulation is applied for the same example to compare the numerical outcomes by the fuzzy interval approach.