危险化学品重大危险源辨识中存在问题的研究与探讨

根据对GB18218—2000《重大危险源辨识》和新标准GB18218—2009《危险化学品重大危险源辨识》以及国内外重大危险源辨识标准的对比分析,提出我国危险化学品重大危险源辨识中存在的四大问题。针对重大危险源涵盖种类仍不齐全的问题,提出将重大危险源从能量和物质两个角度划分,即标准涵盖的危险源种类应加入危险能量重大危险源;针对临界量不合理的问题,提出以死亡半径作为分界点,通过模拟计算确定危险物质的临界量的方法,使确定出的临界量符合相关法律法规规定量;针对重大危险源单元范围划分不合理的问题,提出采用模拟计算,以火灾爆炸事故破坏范围中的财产损失半径来定义单元覆盖距离的方法;针对缺少重大危险源危险性分级方法的问题,通过分析比较国内较为流行的几种重大危险源分级技术的优缺点及适用条件,提出多种分级方法结合的组合式分级方法。     

Patchy Distribution Fields: Sampling Distance Unit of a Spiral Survey and Reconstruction Adequacy

A mathematical model is used to examine the effects of choosing various units of sampling distance of a spiral acoustic survey on the adequacy of reconstructing patchy distribution fields. The model simulates fish or plankton patches (or gaps) of different shapes and spatial orientations, and an acoustic survey by a spiral of Archimedes along which a unit of sampling distance is set. For comparison, surveys are imitated by parallel transects along which the same unit of sampling distance is set. Adequacy of the reconstructed fields to those originally generated is evaluated by calculating their correlations (r). In the case of a spiral survey, the mathematical experiments conducted show that an immovable field can be reconstructed properly (r ² > 0.70) if the ratio of the units of sampling distance to the autocorrelation radius for the field averaged in various directions d/R _av < 1.0–1.5. Regarding immovable fields, the spiral surveys ensure, practically speaking, the same adequacy of the field reconstruction as do surveys by parallel transects with the same unit of sampling distance. In regard to movable fields, a comparison of the results of spiral surveys with those of surveys by parallel transects indicates that the former may ensure even higher adequacy of the field reconstruction than do the latter, provided that the units of sampling distances in these surveys are equal to each other.     

Hydrocarbon Uptake by Roots of Vicia faba (Fabaceae)

Vicia faba was grown in crude oil polluted soil and its roots were extracted for the detection and estimation of hydrocarbons. Saturated and unsaturated Aliphatic Hydrocarbons (AHs) ranging from C₂₂ to C₃₆ were identified in AHs fraction. However, PAHs were not present in the same extract. This could be due to the fact that PAHs being toxic compounds are not accumulated in the plant root extracts of V. faba grown in crude oil polluted soil. Three phytoalexins were identified and estimated by mass spectrometric analysis in the root extracts of V. faba. These three compounds are 2-t-butyl-4-(dimethyl benzyl) phenol, 2, 4-bis (dimethyl benzyl) phenol and 2,4-bis (dimethyl benzyl)-6-butyl phenol. These phenolics in V. faba are being reported for the first time. These compounds are presumably elicited as a direct stress on crude oil hydrocarbons on the roots of this plant.     

Towards the definition of budget models for the evolution of deltas

Global climatic change is likely to take place and could eventually affect Mediterranean deltas and other lowlying coastal regions. This would have serious implications for the natural resources of these deltaic areas, as well as for human settlements and related economic activities. To achieve sound decision making, to prevent damages and to avoid risky investments, it is necessary to understand the integral functioning of deltaic areas and to determine their vulnerability and response to large-scale change phenomena. Optimal use of the available knowledge will require that existing and new field measurements are combined and that integrated (physical/ecological) conceptual models of deltaic behaviour are developed with socio-economics scenarios as boundary conditions. This paper illustrates the methodological effort towards organizing a modeling framework to conduct budget computations at various scales with reference to the most significant ‘physiogrpahic units’ and to the most significant deltaic processes. The final objective is to handle the problem of evaluating possible changes under different scenarios.     

泥磷中温蒸馏提取黄磷设备材料腐蚀特性研究

蒸磷法是国内从泥磷中提取黄磷的最常用方法,但该方法常存在蒸磷釜局部氧化严重、设备腐蚀较快等问题。模拟泥磷中温蒸馏提取黄磷的腐蚀试验,分析了Q235钢、45钢和304不锈钢3种材料在泥磷水分蒸发(100℃)和黄磷提取(290℃)2个阶段中质量与时间、材料腐蚀速率与时间的关系。采用扫描电镜(SEM)对腐蚀较严重的45钢材料进行了微观形貌分析,并分别用能谱分析仪(EDS)和X射线衍射仪(XRD)对腐蚀产物成分及其相组成进行分析。结果表明:在100℃和290℃时,45钢的腐蚀速率最大,Q235钢次之,304不锈钢最小;45钢和Q235不锈钢100℃时腐蚀速率大于290℃时,而304不锈钢100℃时腐蚀速率小于290℃时。研究表明,304不锈钢的抗腐蚀能力最强,其次是Q235钢,而45钢抗腐蚀能力最弱。     

Combining steam injection with hydraulic fracturing for the in situ remediation of the unsaturated zone of a fractured soil polluted by jet fuel

A steam injection pilot-scale experiment was performed on the unsaturated zone of a strongly heterogeneous fractured soil contaminated by jet fuel. Before the treatment, the soil was stimulated by creating sub-horizontal sand-filled hydraulic fractures at three depths. The steam was injected through one hydraulic fracture and gas/water/non-aqueous phase liquid (NAPL) was extracted from the remaining fractures by applying a vacuum to extraction wells. The injection strategy was designed to maximize the heat delivery over the entire cell (10 m × 10 m × 5 m). The soil temperature profile, the recovered NAPL, the extracted water, and the concentrations of volatile organic compounds (VOCs) in the gas phase were monitored during the field test. GC-MS chemical analyses of pre- and post-treatment soil samples allowed for the quantitative assessment of the remediation efficiency. The growth of the heat front followed the configuration of hydraulic fractures. The average concentration of total hydrocarbons (g/kg of soil) was reduced by ～ 43% in the upper target zone (depth = 1.5-3.9 m) and by ～ 72% over the entire zone (depth = 1.5-5.5 m). The total NAPL mass removal based on gas and liquid stream measurements and the free-NAPL product were almost 30% and 2%, respectively, of those estimated from chemical analyses of pre- and post-treatment soil samples. The dominant mechanisms of soil remediation was the vaporization of jet fuel compounds at temperatures lower than their normal boiling points (steam distillation) enhanced by the ventilation of porous matrix due to the forced convective flow of air. In addition, the significant reduction of the NAPL mass in the less-heated deeper zone may be attributed to the counter-current imbibition of condensed water from natural fractures into the porous matrix and the gravity drainage associated with seasonal fluctuations of the water table.     

空气隙膜蒸馏膜污染控制实验研究

采用空气隙膜蒸馏组件,采用美国进口膜,以自来水、伞盖3号原水和苦咸水为工质,实验分析了膜污染情况,结果显示:料液无旋转时,自来水间歇累计运行32 h后出现污染;质量分数分别为20%和50%的盐水8 h后传质通量降低到最初通量32%和12%;3号原水瞬时产生污染,经砂滤处理后为苦咸水,传质通量比原水提高4倍～5倍,运行8h后通量下降到初始通量的6%。削弱膜污染方法采用最优参数的三向旋转入流组件(α=70°、δ=2 mm、β=45°),自来水进入污染期由32 h推迟到65 h,传质通量比无旋转增大近20%;采用具有分水盘的并接式空气隙膜组件,开槽2 mm膜污染较严重,开槽3 mm的膜通量比无旋转入流传质通量平均增大60%,两种组件设计形式均可提高膜通量,一定程度缓解了膜污染的产生。     

油田化工污水中总氰化物的检测

采用在线蒸馏-流动注射分析法检测大庆油田化工污水中总氰化物。分析流速和温度对流动注射仪检测结果的影响,得出结论:载流流速为1.8mL/min,显色剂流速在1.3mL/min,缓冲溶液流速稳定在1.6mL/min时,分析精度最好;显色反应在60℃以下进行时,可以消除温度差异对检测结果的干扰。该方法适用于油田化工废水中总氰化物的检测。     

Fuzzy fault tree analysis for fire and explosion of crude oil tanks

Crude oil tank fire and explosion (COTFE) is the most frequent type of accident in petroleum refineries, oil terminals or storage which often results in human fatality, environment pollution and economic loss. In this paper, with fault tree qualitative analysis technique, various potential causes of the COTFE are identified and a COTFE fault tree is constructed. Conventional fault tree quantitative analysis calculates the occurrence probability of the COTFE using exact probability data of the basic events. However, it is often very difficult to obtain corresponding precise data and information in advance due to insufficient data, changing environment or new components. Fuzzy set theory has been proven to be effective on such uncertain problems. Hence, this article investigates a hybrid approach of fuzzy set theory and fault tree analysis to quantify the COTFE fault tree in fuzzy environment and evaluate the COTFE occurrence probability. Further, importance analysis for the COTFE fault tree, including the Fussell–Vesely importance measure of basic events and the cut sets importance measure, is performed to help identifying the weak links of the crude oil tank system that will provide the most cost-effective mitigation. Also, a case study and analysis is provided to testify the proposed method.     

地势起伏度对三峡库区人口及经济发展水平的影响

在1[DK]∶10万三峡库区DEM的基础上,采用窗口分析等方法提取了地形起伏度,利用均值变点分析方法确定三峡库区地势起伏度的最佳统计单元是015 km2。首次绘制了基于最佳统计单元的三峡库区地势分布图,确定地形起伏度是影响三峡库区人口分布和经济发展的重要因素之一。在系统分析了三峡库区地形起伏度的分布规律基础上,选择城镇化率、农村居民恩格尔系数、经济密度、人口密度等指标,定量揭示地形起伏度对人口和经济发展的影响。结果显示三峡库区的地形总体以起伏山地为主。地形起伏度与人口密度、经济密度呈极显著的负相关,地势起伏度大的区域,人口密度较小,经济发展相对滞后,农村居民生活相对贫困。地势起伏度小的区域,人口密度较大,经济相对发达。这对认知山区人口和经济的空间格局,将三峡库区资源开发利用以及产业布局在适度的地势起伏度范围,对于有效进行三峡库区资源开发、促进区域经济效益最大化具有重要的参考价值