基于颗粒计数的喷气燃料中固体颗粒沉降性研究

喷气燃料中的固体颗粒污染物会增大飞机发动机精密部件磨损,堵塞飞机燃油系统,引发飞行事故。在我国的机场油库,常使用静置沉降法来提高油罐中喷气燃料的洁净性,但其作用效果很难通过目测法或者微孔过滤重量法从颗粒的尺寸大小和数量分布上进行分析。基于此,将基于颗粒计数对喷气燃料中固体颗粒的沉降性进行研究,利用自动颗粒计数器来研究静置沉降对储油罐中喷气燃料的不同尺寸固体颗粒污染物数量变化的影响,从而研究其作用效果。     

Influence of solid contaminants in oil on wear characteristics of nano-Al2O3／Ni composite coating

Solid conlaminants in Iubrication system will cause severe wear of sliding components. In order 1o improve the wear resistance of the material in oil containing solid contaminants, the brush plated nano-Al2O3/Ni composite coating was prepared and the influence of the sand content and sand size on the tribological property of the coating in oil containing solid contaminants was tested with ball-on-disc tester. The results show that the wear volume increases with increasing the sand content and sand size, and the wear resistance of the composite coating is 20% higher than that of the high-speed plain nickel coating. The main wear mechanisms of the coatings are abrasive wear and adhesive wear. And due to the nano-particle strengthening effect, the wear resistance of the composite coating is improved.     

有机膨润土作为防渗垫层材料的性能研究

以十六烷基三甲基氯化铵为改性剂合成制备了有机膨润土,并考察其作为防渗垫层材料的性能.研究发现,有机膨润土能有效截留渗漏液中的有机污染物,阻止其向环境的迁移,具有较好的防渗效果.研究还发现,改性剂用量对防渗性能具有一定的影响,十六烷基三甲基氯化铵用量为5%(质量分数)时可以获得防渗性能较好的有机膨润土材料.当渗漏液体积足够大时,有机膨润土防渗层会被穿透,且穿透体积随渗漏液初始浓度的增加而减少.     

多孔介质中化学–热–水力–力学耦合过程本构模型和数值模拟

本文发展了一个多孔介质中的化学–热–水力–力学(CTHM)耦合本构模型。该模型基于文献[1]中多孔介质热–水力–力学(THM)本构模型、文献[2,3]中的污染物传输本构模型和文献[4]提出的化学–力学本构模型。在本构模型中引入化学软化函数以模拟孔隙水中有机污染物对多孔介质力学性质的影响。考虑了温度对污染物传输机制的影响。本文CTHM耦合本构模型已在多孔介质的热–水力–力学–污染物传输数学模型中建立。在CTHM本构模拟框架中对计及化学塑性效应、描述在热–水力–污染物传输耦合作用下多孔介质力学行为、在应力–吸力–温度四维空间中包含了五重屈服面的耦合本构模型发展了一致性切线模量矩阵。数值结果突出显示了污染物浓度在多孔介质化学–热–水力–力学(CTHM)耦合系统中的影响。     

Distribution and transport of sediment-bound metal contaminants in the rio grande de tarcoles, costa rica (Central America)

A reconnaissance survey of the extent of metal contamination in the Rio Grande de Tarcoles river system of Costa Rica indicated high levels of chromium (Cr) in the fine-grain bed sediments (<60 μm) of tributaries downstream from leather tanneries (50–83 times Cr background or 3000–5000 μg/g). In the main channel of the river downstream of the San Jose urban area, Cr contamination in sediments was 4–6 times background and remained relatively constant over 50 km to the mouth of the river. Sediments from a mangrove swamp at the river mouth had Cr levels 2–3 times above background. Similar patterns of dilution were observed for lead (Pb) and zinc (Zn) sediment contamination, although the contamination levels were lower. The high affinity of Cr towards particulate phases, probably as Cr(III), allows the use of Cr contamination levels for delineating regions of deposition of fine-grained sediments and dilution of particle associated contaminants during transport and deposition.     

微量物质对乙烯装置的影响

微量物质可随裂解原料、稀释蒸汽和化学助剂进入乙烯装置,对裂解炉炉管造成损害、腐蚀管线与设备、使催化剂中毒,甚至影响下游聚烯烃装置的运行。乙烯装置中常见的微量物质主要有重金属、非金属及氧化物。硫会增加裂解产物中硫化氢的生成量,羰基硫可造成丙炔和丙二烯加氢催化剂活性下降,并污染丙烯产品;砷会腐蚀炉管并使加氢催化剂失活;钠会造成炉管腐蚀,加剧炉管内的结焦,还会促进CO和CO2的生成;汞能在低温设备中累积,侵蚀铝合金,造成设备故障,并降低催化剂的活性;CO2、甲基叔丁基醚、甲醇、氯化物及一些金属元素也会对乙烯装置产生不利影响。     

Tetrachloroethylene and hexachloroethane degradation in Fe(III) and Fe(III)–citrate catalyzed Fenton systems

BACKGROUND: Tetrachloroethylene (PCE) and hexachloroethane (HCA) degradation, individually and in mixture, is investigated by Fe(III) or Fe(III)‐citrate initiated Fenton reaction under a range of hydrogen peroxide (H₂O₂) concentrations to illustrate the applicability and constraints of Fenton chemistry in degrading contaminants in polluted groundwater. RESULTS: In individual solutions Fe(III) rapidly degraded PCE for all H₂O₂ concentrations, but HCA at ≥ 0.2 mol L^?1 H₂O₂; the apparent PCE degradation rate initially increased but then decreased with increasing H₂O₂, while the HCA degradation rate was either unaffected or increased. With Fe(III)‐citrate PCE degradation was lower and no HCA degradation occurred. PCE degradation was lower in PCE‐HCA mixture, but the trend with H₂O₂ concentration was similar to the individual chemical; for HCA the residual was smaller for higher H₂O₂ concentration, but the apparent degradation rate constant was unaffected. CONCLUSION: Fe(III) catalyzed reactions can potentially degrade chemicals through reductive as well as oxidative transformations. Degradation of chemicals in mixtures occurs at a slower rate due to competition for radical moieties. The Fe(III)‐citrate complex further slowed chemical transformation. This study expands on the use of different forms of iron to catalyze the Fenton reaction to degrade chemicals. Copyright © 2012 Society of Chemical Industry     

Application of colloidal gas aphrons for pollution remediation

Colloidal gas aphrons (CGAs), first described by Felix Sebba in his book Foams and Biliquid Foams—Aphrons in 1987, consist of a system of spherical microbubbles with diameters mostly above 25 µm and classified as kugelschaums (ball foam). They possess some colloidal properties and can be pumped at uniform rate through pipes and channels, much like liquids. Also, they have high stability due to very small size and thick surfactant shells. Research work published over the past two decades indicate effective applications of CGAs for clarification of particles and microorganisms, protein separation, gas and nutrient transfer and pollutant separation from water and soil matrices. In this review paper, the techniques for generating CGAs and their application to pollution abatement are discussed. Some mineral separation processes by CGA flotation have also been reviewed because of their relevance to contaminant removal processes. The CGAs were found to function on the principles of bubble entrained floc flotation, electrostatic and ionic interaction, diffusion of entrapped gas and hydrophobicity of the pollutant particles. Two tables have also been provided to present a comparative overview of the generation technologies and the effectiveness of pollution remediation techniques. Copyright © 2012 Society of Chemical Industry     

Speciation of trace inorganic contaminants in corrosion scales and deposits formed in drinking water distribution systems

Sequential extractions utilizing the modified Tessier scheme (Krishnamurti et al., 1995) and measurements of soluble and particulate metal released from suspended solids were used in this study to determine the speciation and mobility of inorganic contaminants (As, Cr, V, U, Cd, Ni, and Mn) found in corrosion scales and particles mobilized during hydraulic flushing events. Arsenic, chromium and vanadium are primarily associated with the mobilization-resistant fraction that is resistant to all eluents used in this study and also bound in highly stable crystalline iron oxides. Very low concentrations of these elements were released in resuspension experiments. X-ray absorbance measurements demonstrated that arsenic in the sample with the highest As concentration was dominated by As(V) bound by iron oxides. Significant fractions of uranium and cadmium were associated with carbonate solids. Nickel and manganese were determined to be more mobile and significantly associated with organic fractions. This may indicate that biofilms and natural organic matter in the drinking water distributions systems play an important role in the accumulation and release of these inorganic contaminants.     

低渗透油田提高单井产量技术应用及评价

油水井在修井、开采过程中造成地层污染,产量下降,为了稳定并提高单井产量,开展了堵塞机理研究、低产原因分析、不同油藏工艺措施优选等研究与应用,近几年主要采取的措施类型主要有土酸酸化、暂堵酸化、乳化酸酸化等措施类型,但随着油田开发时间的延长,油井含水上升,堵塞类型复杂,并且油井措施次数增加,部分井采取常规酸化已经达不到增油降水的目的,因此引进多氢酸酸化、负压返排工艺、泡沫酸酸化、潜在酸酸化等措施,目的在于减缓酸岩反应速度、提高酸化后残液的返排率,减缓油井含水上升速度。