原油降解中微生物群落的16S rDNA-PCR-DGGE分析

为对原油降解过程中微生物群落结构的变化,本文采用直接向原油中加入营养物刺激的方法,获得原油降解菌体系。提取不同培养时间条件下降解菌体系的总DNA,并以之为模板采用PCR-DGGE技术研究了在原油降解过程中微生物群落的组成,结果表明,随着培养时间的不同,微生物的群落结构表现出差异,随着时间的变化其微生物群落也会发生改变。回收了DGGE图谱中的18个条带,测序结果经过Blast比对表明其中10个条带代表的细菌是不可培养的,显示了DGGE技术的优越性。同时采用气相色谱技术对降解过程中的原油烃的变化进行了分析,结果显示原油烃类组分会随着降解菌多样性的变化而发生变化,降解菌体系表现出了其对烷烃类物质的降解能力。     

排水管道噪声简易评价方法设计的研究

建筑排水管道产生的噪声是家庭噪声的主要来源之一,而目前的测定方法系统较复杂、测试时间又长,本文根据管道声学测量理论对排水管道噪声测定方法进行设计,旨在探寻一种排水管道噪声简易的评测方法,以提高实验测试效率,同时又可为排水管材降噪性能研究提供一种简便方法。     

AMDIS在土壤有机污染物鉴别中表征性统计量的探究

土壤样品中有机污染物的GCMS数据经AMDIS处理,其结果报告中就组分对应的色谱峰和质谱棒图来讲给出了大量的定性定量统计量。基于官方标准分析方法中的特定要求和AMDIS对GCMS数据处理结果,首先讨论了有机化合物鉴别中选择和使用保留特性统计量时所应考量的要素,并阐述了保留时间或相对保留时间窗口确立的过程,继而依据是否有标准品来阐明了基于AMDIS进行土壤中有机污染物鉴别所应关注的统计量及应遵从的步骤。从而,为准确高效地使用AMDIS甄别土壤中有机污染物组分奠定了坚实的基础。     

基于正压密封方法的闭式采空区灭火技术

为提高闭式采空区密闭漏风控制效果,基于矿井空气流动基础理论,运用RFPA软件建立了注氮气室正压密封采空区数值模型,模拟分析了注氮气室正压作用对采空区密闭漏风行为的影响规律,提出了基于注氮气室正压密封方法的采空区灭火技术,并在恒大煤矿5333工作面采空区进行了应用.结果表明,在气室内氮气相对正压作用下,通风巷道向采空区漏风速度快速减小至0,并最终产生反向,形成由气室向外部微量漏氮气的状态,5333采空区采取正压密封方法后,内部CO、C2H4和温度快速消失和降低至安全范围值.     

Improved far-field blast predictions from fast deflagrations,DDTs and detonations of vapour clouds using FLACS CFD

The CFD tool FLACS was developed from 1982 with a primary goal to predict gas explosion loads inside oil platform modules. The prediction of far-field blast loads was of secondary importance as any scenario creating a substantial far-field blast would already have collapsed the module where it originated. For the same reason the potential for a deflagration-to-detonation-transition (DDT) was not initially of interest. Over the past decade use of FLACS has been more widespread, and the tool is now frequently used to predict explosions on onshore facilities and FPSOs/FLNGs, where far-field blast loads and evaluation of DDT potential may be of significant interest. Previous work by Hansen et al. (2010) has highlighted a weakness in FLACS when predicting the far-field blast from strong gas explosions and, when using FLACS according to guidelines, far-field blast pressures will often be significantly underpredicted. For scenarios involving DDT this effect will be particularly strong. The current study will present a way to obtain more accurate far-field blast predictions by modified parameter settings in FLACS for strong deflagrations. Using modified settings, it is also possible, with good precision, to predict flame speeds, pressures and far-field blast from DDT-scenarios and directly initiated gas detonations, physics which are beyond the accepted capabilities of FLACS. Selected full-scale experiments from the DNV GL test site at Spadeadam will be used to compare with the simulations. Convincing evidence for DDT in large scale natural gas experiments (91% methane) was found in simulations of one of these tests.     

Flame acceleration in tube explosions with up to three flat-bar obstacles with variable obstacle separation distance

The effect of obstacle separation distance on the severity of gas explosions has received little methodical study. It was the aim of this work to investigate the influence of obstacle spacing of up to three flat-bar obstacles. The tests were performed using methane-air (10% by vol.), in an elongated vented cylindrical vessel 162 mm internal diameter with an overall length-to-diameter, L/D, of 27.7. The obstacles had either 2 or 4 flat-bars and presenting 20% blockage ratio to the flow path. The different number of flat-bars for the same blockage achieved a change of the obstacle scale which was also part of this investigation. The first two obstacles were kept at the established optimum spacing and only the spacing between the second and third obstacles was varied. The profiles of maximum flame speed and overpressure with separation distance were shown to agree with the cold flow turbulence profile determined in cold flows by other researchers. However, the present results showed that the maximum effect in explosions is experienced at 80 to 100 obstacle scales about 4 times further downstream than the position of maximum turbulence determined in the cold flow studies. Similar trends were observed for the flames speeds. In both cases the optimum spacing between the second and third obstacles corresponded to the same optimum spacing found for the first two obstacles demonstrating that the optimum separation distance does not change with number of obstacles. In planning the layout of new installations, the worst case separation distance needs to be avoided but incorporated when assessing the risk to existing set-ups. The results clearly demonstrate that high congestion in a given layout does not necessarily imply higher explosion severity as traditionally assumed. Less congested but optimally separated obstructions can lead to higher overpressures.     

外错型走向高抽巷瓦斯抽采技术应用研究

为探究外错型高抽巷在实际应用中的适用性、可行性以及多功能性,以李雅庄矿2-603工作面外错型高抽巷为研究对象,在考察矿井实际情况的基础上采用理论分析和数值模拟对外错型高抽巷的治理效果进行分析。得出:外错型高抽巷相较于内错型高抽巷巷道位移量小,便于管理;外错型高抽巷不但能作为下一工作面采空区的内错型高抽巷,并且从其内部向下打穿层钻孔能保证下一工作面掘进工作的安全进行。根据现场实测数据分析,外错型高抽巷钻孔抽采的平均抽采浓度在27.38%左右,平均抽采纯量在22.45m3/min左右,上隅角瓦斯基本保持在0.3%左右。外错型高抽巷"一巷多用"的特点,既能满足矿井安全生产的要求,也可以提高经济效益。     

工业类棕地再生特征初探——兼论美国煤气厂公园污染治理过程

中国目前面临着前所未有的大规模城镇化进程与产业升级,大量传统工业企业搬迁或改制,工业类棕地大面积暴露。在空间特征上,工业类棕地的场地地形基本平坦,最显著的空间元素为大型的工业建筑遗产。在污染特征上,此类棕地的污染以土壤污染与地下水污染为主,隐蔽性强、潜伏期长,项目周期长且具有不确定性。著名的美国西雅图市煤气厂公园经历了长达半个多世纪、几轮的环境勘测与污染治理过程,至今场地中仍然可能残存有污染物质,充分体现了工业类棕地的上述特征。     

Occurrence of PCBs and PAHs in an urban soil of Madrid (Spain)

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were analysed in surface soil samples collected in 2001–2002 at an open urban area of Madrid. In order to obtain representative samples, three collection points at the site were chosen. The most abundant PAHs and PCBs were phenanthrene, fluorene, pyrene, chrysene and benzo[a]pyrene and hexa- and heptachlorinated PCBs, respectively. The sum of selected PAHs (13 compounds) and PCBs (15 congeners) averaged 1 and 0.1?µg?g^?1, respectively. PCB levels in winter were 2–10 times higher than summer ones, while seasonal variation for most of PAHs were not observed. Good correlations among all PCBs were found. Five PAHs were also well correlated.     

Experimental and numerical investigation of constant volume dust and gas explosions in a 3.6-m flame acceleration tube

This paper describes an experimental investigation of turbulent flame propagation in propane-air mixtures, and in mechanical suspensions of maize starch dispersed in air, in a closed vessel of length 3.6 m and internal cross-section 0.27 m × 0.27 m. The primary motivation for the work is to gain improved understanding of turbulent flame propagation in dust clouds, with a view to develop improved models and methods for assessing explosion risks in the process and mining industries. The study includes computational fluid dynamics (CFD) simulations with FLACS and DESC, for gas and dust explosions respectively. For initially quiescent propane-air mixtures, FLACS over-predicts the rate of combustion for fuel-lean mixtures, and under-predicts for fuel-rich mixtures. The simulations tend to be in better agreement with the experimental results for initially turbulent gaseous mixtures. The experimental results for maize starch vary significantly between repeated tests, but the subset of tests that yields the highest explosion pressures are in reasonable agreement with CFD simulations with DESC.