瓦斯充气防爆的负熵机理

借助于耗散结构理论，分析了瓦斯引爆的温熵图及防爆的负熵机理，并对充Ｎ２抽放低浓度瓦斯的可行性进行了探讨。     

The effect of orifice plates with different shapes on explosion propagation of premixed methane–air in a semi-confined pipeline

The effect of internal shape of obstacles on the deflagration of premixed methane–air (concentration of 10%) was experimentally investigated in a semi-confined steel pipeline (with a square cross section size of 80 mm × 80 mm and 4 m long). The obstacles used in this study were circular, square, triangular and gear-shaped (4-teeth, 6-teeth and 8-teeth) orifice plates with a blockage ratio of 75%, and the perimeter of the orifice was regarded as a criterion for determining the sharpness of the orifice plate. The overpressure history, flame intensity histories, flame front propagation speed, maximum flame intensity and peak explosion overpressure were analyzed. The explosion in the pipeline can be divided into two stages: initial explosion and secondary explosion. The secondary explosion is caused by recoiled flame. The perimeter is positively related to the intensity of the recoiled flame and the ability of orifice plate to suppress the explosion propagation. In addition, the increase in the perimeter will cause the acceleration of the flame passing through the orifice plate, while after the perimeter of the orifice reaches a certain value, the effect of the increase in perimeter on explosion excitation becomes no obvious. The overpressure (static pressure) downstream of the orifice plate is the result of the combined effect of explosion intensity and turbulence. The increase in perimeter leads to the increase in turbulence downstream of the orifice plate which in turn causes more explosion pressure to be converted into dynamic pressure.     

A preliminary explore to the forced ventilation on the toxic gas release/dispersion and the hazard mitigation within a petrochemical plant

More than thirty-five years ago, the Bhopal disaster shook the whole world and investigators found out that many people survived just because they turned on the fans in their bedrooms. It was postulated that the forced ventilation played an important role in diluting the toxic gas and saved these people. In order to provide evidence to solve this old mystery, this research employed FLACS software to assess the hazardous degree of a toxic gas (hydrogen sulfide) leakage within a petrochemical process. Series of gas dispersion simulations were performed to actualize the hazardous characteristics and the corresponding risks of the release accident. The study shows that the hazardous level and the hazard range can be greatly influenced when parameters, such as the gas leakage circumstances (atmospheric conditions and wind speed) and the mitigation measures (direction of fans and their speed) are altered.By using explosion-proof fans in different positions and ventilation directions, combined with the natural wind in a certain direction, this research attempts to detect the best combination from various mitigation designs and to compare the influence of fan directions on hazard mitigation. It is also the first time of its kind to simulate the effect of forced ventilation on hazard mitigation within a process plant. The results show that the hazardous level of a toxic release can be effectively alleviated, when the direction of the mechanical ventilation is against the natural wind direction. With the help of the CFD simulation and the quantitative risk analysis technique, different loss prevention strategies can be tested via this method in order to establish a safer working environment.     

Assessing the influence of real releases on explosions: Selected results from large-scale experiments

The research activities in the project Assessing the Influence of Real Releases on Explosions (AIRRE) included a unique series of large-scale explosion experiments with high-momentum jet releases directed into congested geometries with subsequent ignition. The primary objective for the AIRRE project was to gain improved understanding of the effect that realistic releases and turbulent flow conditions have on the consequences of accidental gas explosions in the petroleum industry. A secondary objective was to develop a methodology that can facilitate safe and optimal design of process facilities. This paper presents selected results from experiments involving ignition of a highly turbulent gas cloud, generated by a large-scale, pressurised release of natural gas. The paper gives an overview of the effect on maximum explosion overpressures of varying the ignition position relative to the release point of the jet and a congested region placed inside the flammable cloud, with either a high or a medium level of congestion. For two of the tests, involving a jet release and the medium congestion rig, the maximum overpressures significantly exceeded those obtained in a quiescent reference test. The paper presents detailed results for selected tests and discusses the effect of the initial flow field generated by realistic releases – including turbulence, net flow and concentration gradients – on relevant explosion phenomena.     

The asymmetric scent: ringtailed lemurs (<Emphasis Type="Italic">Lemur catta</Emphasis>) have distinct chemical signatures in left and right brachial glands

Distinctive cues are predicted to evolve when the benefits obtained by the recognition process overcome its costs. When individual recognition is particularly beneficial for both senders and receivers, the expression of strongly distinctive signals is predicted to evolve. On the other hand, it could be predicted that each individual should show a very stable individual signature. In the same perspective, a great stability of the individual signatures could be expected. Lemur catta is the first non-human primate in which olfactory individual recognition has been demonstrated on the basis of the specialized brachial gland secretions. In this paper, I performed gas chromatograph analyses of right and left gland samples collected in two different periods (breeding and non-breeding seasons) from seven males. The aim was to verify if a diversification in such cues, already demonstrated at the inter-individual level, also occurs at the intra-individual level between left and right glands. I verified, by discriminant analysis and chemical distance comparisons, that each gland of each lemur has its particular signature that is maintained through time. Moreover, such diversification resulted so marked to make the overall intra-individual chemical differences similar to/as strong as the inter-individual ones. Since in rodents several odors from different glands may be integrated in individual recognition, I suggest that bilateral diversification in L. catta scents may offer an enhanced distinctiveness that could provide benefits in mate choice and social relationships.     

“离子液”新技术在巴彦淖尔紫金制酸尾气脱硫工程的应用

采用“离子液”新技术处理有色金属冶炼制酸尾气,工程运行结果表明,制酸尾气出口的SO2远远小于《大气污染物综合排放标准）GB16297—1996）中的排放标准,该工程具有工艺流程简洁、设备少、自动化程度高;无新生固体、气体排放,无强噪声,少量废水,不产生二次污染;并且相对能耗较低,占地面积小等优点。     

气相色谱法对土壤和植物中毒鼠强的测定

采用气相色谱法测定土壤和植物中的毒鼠强,用苯作为提取剂,中性氧化铝-硅镁柱净化。土壤和植物的回收率分别为84.0%~87.0%8、1.4%~86.0%,样品最低检出量为20ng/g。     

Role of heavy polar organic compounds for water repellency of sandy soils

Separation and chemical characterisation of specific compounds responsible for soil water repellency has not previously been achieved. Here we describe the extraction, separation and analysis by gas chromatography-mass spectrometry of organic compounds found in wettable and water repellent sandy soils from the Netherlands and United Kingdom. Fatty acids (C₁₆–C₂₄), amides (C₁₄–C₂₄), alkanes (C₂₅–C₃₃), aldehydes/ketones (C₂₃–C₃₁) and complex ring-containing structures were detected in all samples. We found a greater abundance of high molecular mass polar compounds in the water repellent samples.     

Sorption of lambda-cyhalothrin,cypermethrin, deltamethrin and fenvalerate to quartz,corundum, kaolinite and montmorillonite

Sorption to mineral surfaces may be important for retention and degradation of hydrophobic pesticides in subsoils and aquifers poor in organic matter. In this work the title pyrethroids have been used to investigate selective interactions with the surfaces of four minerals. Sorption of the four pyrethroids was quantified in batch experiments with initial pyrethroid concentrations of 1–100 μg/l. Sorption to centrifuge tubes used in the batch experiments accounted for 25–60% of total sorption. Net sorption was obtained from total sorption after subtracting the amounts of pyrethroids sorbed to centrifuge tubes used. All isotherms could be fitted by the Freundlich equation with n ranging between 0.9 and 1.1. Bonding affinities per unit surface area decreased in the order: corundum>quartz>montmorillonitekaolinite. A similar sequence as found for the total surface tension of the minerals. All minerals showed the same selectivity order with respect to sorption affinity of the four pyrethroids: lambda-cyhalothrin>deltamethrin>cypermethrin>fenvalerate, which shows that the most hydrophobic compound is sorbed most strongly. Stereochemical properties of the four pyrethroid formulations may also contribute to the selectivity pattern.     

A statistical comparison of naphthenic acids characterized by gas chromatography-mass spectrometry

Naphthenic acids are complex mixtures of alkyl-substituted acyclic and cycloaliphatic carboxylic acids, with the general chemical formula C_nH_2n+zO₂, where n is the carbon number and Z specifies a homologous family. These acids have a variety of commercial uses, including being used as wood preservatives. They are found in conventional and heavy oils, and in the oil sands of northeastern Alberta, Canada. Naphthenic acids are major contributors to the toxicity of tailings waters that result from the oil sands extraction process. Eight naphthenic acids preparations (four from commercial sources and four from the oil sands operations) were derivatized and analyzed by gas chromatography–mass spectrometry. The composition of each mixture was summarized as a three-dimensional plot of the abundance of specific ions (corresponding to naphthenic acids) versus carbon number (ranging from 5 to 33) and Z family (ranging from 0 to −12). The data in these plots were divided into three groups according to carbon number (group 1 contained carbon numbers 5–14, group 2 contained carbon numbers 15–21, and group 3 contained carbon numbers 22–33). A t-test, using arcsine-transformed data, was applied to compare corresponding groups in samples from various sources. Results of the statistical analyses showed differences between various commercial naphthenic acids preparations, and between naphthenic acids from different oil sands ores and tailings ponds. This statistical approach can be applied to data collected by other mass spectrometry methods.