A closer look at BLEVE overpressure

The overpressure produced by the boiling liquid expanding vapor explosion (BLEVE) is still not well understood. Various methods have been published on the overpressure modeling in the far field. They mostly differ by the modeling of the expansion energy, used to scale the distance to the source where the overpressure needs to be calculated. But these methods usually include a experimentally fitted reduction factor, and are mostly overestimating the overpressures. Today there is a growing interest in modeling the BLEVE overpressure in the near field, for studying the blast effect on critical infrastructure such as bridges and buildings. This requires a much better understanding of the BLEVE blast. This paper goes deeper in the understanding of the physical phenomenon leading to the BLEVE blast wave generation and propagation. First, mid-scale BLEVE experiments in addition to new experimental data for near field blast from a small scale supercritical BLEVE are analyzed. And second, an analysis method of the shocks observed in the experiments is presented based on fundamental gas dynamics, and allows the elaboration of a new modeling approach for BLEVE overpressure, based on the calculation of the initial overpressure and radius of the blast.     

A new leak location method based on leakage acoustic waves for oil and gas pipelines

In order to study a new leak detection and location method for oil and natural gas pipelines based on acoustic waves, the propagation model is established and modified. Firstly, the propagation law in theory is obtained by analyzing the damping impact factors which cause the attenuation. Then, the dominant-energy frequency bands of leakage acoustic waves are obtained through experiments by wavelet transform analysis. Thirdly, the actual propagation model is modified by the correction factor based on the dominant-energy frequency bands. Then a new leak detection and location method is proposed based on the propagation law which is validated by the experiments for oil pipelines. Finally, the conclusions and the method are applied to the gas pipelines in experiments. The results indicate: the modified propagation model can be established by the experimental method; the new leak location method is effective and can be applied to both oil and gas pipelines and it has advantages over the traditional location method based on the velocity and the time difference. Conclusions can be drawn that the new leak detection and location method can effectively and accurately detect and locate the leakages in oil and natural gas pipelines.     

Safety-related conclusions for the application of ultrasound in explosive atmospheres

International safety regulations such as EN 1127-1 consider ultrasound to be an ignition source. Currently, applications of ultrasound in explosive atmospheres have to comply with a threshold value of 1 mW/mm². However, it is unclear as to how this intensity has to be measured and, therefore, this threshold value is poorly defined. Moreover, it is based on theoretical estimations in analogy to other ignition sources and there are no publications or significant records on these estimations. Within a research project at PTB, it has now been investigated experimentally in relation to worst-case considerations including airborne ultrasound, focused MHz ultrasound in liquids and acoustic cavitation. On the basis of the results of the research it is now possible to revise the current regulations and to specify measures for safe operation of ultrasonic applications in explosive atmospheres. In this context, for ultrasound coupled directly to gaseous atmospheres a new threshold value of 170 dB (re. 20 μPa) can be suggested, and for ultrasonic applications in liquids, an augmentation can be made to the threshold to 400 mW/mm².     

Climate hazards: Lessons from recent events in the United States

Three recent cases of climate extremes are studied to identify human impacts and response strategies and to identify common characteristics that may help illuminate the nature of climate hazards. The 1980 heat wave in the central United States, 1981 cold wave in Boston, Massachusetts, and recent flooding and lake level rise in northern Utah, illustrate several important aspects of climate hazards that separate them from the more traditional set of catastrophic events (e.g. tornadoes, hurricanes and earthquakes) usually dealt with by hazards research and management. Among those characteristics are an emphasis on health impacts rather than physical damage, accumulative effects rather than short shocks, a tendency for impacts to accrue to certain socio-economic classes, and relatively slow onset. The management and research implications of these hazard characteristics are explored.     

镉─邻菲啰啉配合物吸附波的研究与应用

在ｐＨ３．３的盐酸－醋酸钠介质中．镉－邻菲啉配合物在－０．６５Ｖ（ｖＳ．ＳＣＥ）处产生一灵敏的吸附波，其二次导数波高与镉浓度在０．０００６～０．１ｍｇ／Ｌ范围内呈良好的线性关系，检出下限达０．０００３ｍｇ／Ｌ。极谱波性质的研究表明该波具有配合物吸附波的特征。方法已用于环境水样中微量错的测定，结果与其它方法吻合。     

超声波萃取-高效液相色谱法测定总悬浮颗粒物中的多环芳烃

研究了一种用中流量采样器采样,超声波萃取,硅镁型吸附剂柱层析预分离.高效液谱测定总悬浮颗粒物的实验方法,在16分内可分高萘、蒽、芘、苯并(a)芘、苯并(ghi)苝等15种多环芳烃.已在大气环境的实际监测中得到应用.     

气浮溶气新技术应用研究

介绍对炼油厂净化水车间一级浮选2^#池的改造，并与未改造的1^#池进行工业应用对比试验。试验结果表明，改造后大大提高了气浮处理效果，平均除油率达85％，且除油效果稳定，出水合格率比对比池提高20．4％。     

超声与紫外光协同氧化法处理染料废水的工艺研究

对超声波、紫外光协同氧化方法处理碱性红B染料废水进行了研究，探讨了水样初始浓度、初始pH值对其脱色效率的影响。并在各条件下，对超声波、紫外光单独作用和两者协同作用下的结果进行了对比。结果表明，超声波与紫外光的协同作用效果明显，染料的降解过程符合准一级动力学方程，在温度30℃、初始浓度50m/L、pH＝1．5、饱和气体为氧气、紫外光波长为253．7nm时，酸性工B经协同处理60min，脱色率可达99．1％。     

水中酚类有机污染物HPLC分析及其应用

超声辐照技术降解水中有机污染物，其降解效率的主平价需要简单、快捷和精确的分析方法。为此研究了5种优先控制酚类污染物的HPLC分离及定量分析方法，方法的定量范围为0.4-100mg/L，检测限介于0.34-0.79ng/μL。4－氯酚的超声降解实验表明，随着反应溶液中4－氯酚初始浓度的降低，降解效率明显提高，因此该方法适用于超声降解过程中酚类污染物的跟踪测定。     

移动通信基站的环境电磁辐射测量与分析

选择设于上海市区及郊区的５座典型移动通信基站，对其一半电磁波辐射强度进行了规范布点监测经数据计算分析及与国家有关电磁辐射防标准比较认为，移动基站周围环境中是磁辐射强度随着离基站天线距离增加大而减少小，在人群可能到达的距天线最近的地方，辐射水平最大值为１．５Ｖ／ｍ，未超过国家标准限值。