Determination of fatty acid derivatives in fuel and diesel oil

Fuel oil plays one of the most important roles as thermal energy source in domestic application. Due to its common use, a careful monitoring of the grade and the deviation of the quality is required. Recently it has been observed that the presence of polar fatty acid derivatives is leading to problems in the fuel injection systems and consequently can cause a damage of the engine. A fast and reliably working procedure is presented, which allows the group determination of these polar compounds, namely glycerides, soaps and fatty acids. A sample preparation succeeded, which accomplishes the extraction, the clean up and the derivatization in one single reaction vessel. Derivatives were methylated with acetyl chloride and methanol and quantified with gas chromatography mass spectrometry. The complexity of fuel oil requires a careful elaboration of the clean up and the extraction procedure. Owing to the novelty of this procedure an accurate investigation and optimization of influential parameters were performed. Optimum conditions for the solid phase extraction with polar sorbents were provided for all target compounds. Additionally, the necessity of the clean up is shown with the relation between investigated analytes and matrix effects. Finally, method performance was verified with an accurate validation and analyses of spiked samples.     

高精度气体水雾含量测量方法的研究

研究了一种快速高精度测量气体中水雾含量的方法.当含有水雾的气体通过装有玻璃纤维的采样管时,多种过滤机制使水雾沉降到玻璃纤维表面,通过称量玻璃纤维滤筒的重量差,可计算出气体的水雾含量.分析结果表明:当玻璃纤维直径为5 μm时,其过滤层对水雾的收集效率大于99%;采用高纯度的玻璃纤维,可以减小其在烘箱中的失重.当玻璃纤维纯度为99.5%时,经7 h加热后,失重小于0.1 mg;玻璃纤维床层阻力和收集效率随液滴平均粒径增大而增加,对于平均粒径为1 μm 的水雾粒子,其收集效率大于99.5%.玻璃纤维过滤法比吸附法和光学法测量精度高,重复性和稳定性好,且测量结果不受环境和气体温度的影响.     

Deterministic global optimization approach to steady-state distribution gas pipeline networks

Natural gas is normally transported through a vast network of pipelines. A pipeline network is generally established either to transmit gas at high pressure from coastal supplies to regional demand points (transmission network) or to distribute gas to consumers at low pressure from the regional demand points (distribution network). In this study, the distribution network is considered. The distribution network differs from the transmission one in a number of ways. Pipes involved in a distribution network are often much smaller and the network is simpler, having no valves, compressors or nozzles. In this paper, we propose the problem of minimizing the cost of pipelines incurred by driving the gas in a distribute non-linear network under steady-state assumptions. In particular, the decision variables include the length of the pipes’ diameter, pressure drops at each node of the network, and mass flow rate at each pipeline leg. We establish a mathematical optimization model of this problem, and then present a global approach, which is based on the GOP primal-relaxed dual decomposition method presented by Visweswaran and Floudas (Global optimization in engineering design. Kluwer book series in nonconvex optimization and its applications. Kluwer, Netherlands, 1996), to the optimization model. Finally, results from application of the approach to data from gas company are presented.     

“三高井”试油测试工艺探讨

总结了三高井测试的设计原则、常用的试油测试工艺及工序,分析了试油施工中出现的意外情况,归纳出三高油气井试油施工的注意事项。     

X射线荧光光谱法测定黄金首饰金含量不确定度的评定

黄金首饰的表层元素经X射线激发,发射出特征X射线荧光能量光谱线.不同元素的能量光谱线与其含量存在着特定的线性关系.能量色散X射线荧光光谱仪通过采用脉冲高度分析器和配套的相关软件将不同能量的脉冲分开,找出相应的元素,测量相应元素的具体含量值.通过X射线荧光光谱仪对黄金首饰的金含量测出的一系列测量值,依据GB/T18043-2013对黄金首饰样品金含量的不确定度进行计算.对采用的黄金标准物质运用最小二乘法建立数学模型,以标准值为x,3次测量值的平均值为y,找出线性关系方程.通过标准物质的运用,当置信因子k=2时,最终分别计算出18K金样品、足金样品金含量的扩展不确定度.     

浅谈水电站达标投产管理工作经验

工作实践证明,在水电站工程建设过程中开展达标投产工作,是全面提高工程建设质量水平的重要方法,有利于水电站整体竣工移交,有利于水电站一次投产发电,能够确保工程尽快发挥经济效益。本文内容是笔者在梨园水电站4年多参与达标投产工作的心得,对水电站建设工作者,具有积极的参考意义。     

工程堆积体土石质边坡径流特征及其产沙效应

工程堆积体边坡侵蚀产沙是生产建设项目区新增水土流失的主要来源之一。通过室内模拟降雨试验,以土质边坡为对照,研究了不同雨强(1. 0 mm/min、2. 5 mm/min)不同砾石质量含量(10%～30%)条件下风沙区工程堆积体土石质边坡径流强度与流速特征及其对产沙的影响。结果表明:(1)各雨强下径流强度随砾石含量增大先减后增,10%砾石含量堆积体边坡径流强度较土质边坡降低3. 3%～38. 6%,20%～30%砾石含量堆积体坡面径流强度较土质坡面增加7. 7%～94. 7%。(2)含砾石边坡流速较土质边坡降低0～45. 8%。1. 0～2. 0 mm/min雨强下,流速随砾石含量增大变化趋势与径流强度一致,而在2. 5 mm/min雨强下则持续减小。(3)土质边坡流速与径流强度关系可通过幂函数描述(P 0. 01),而砾石含量越高,雨强越大时,二者之间的关系转变为开口向下的二次函数形式(P 0. 01)。(4)次降雨产沙量与径流流速、径流强度及其二者交互项呈极显著线性相关关系,其中,流速可作为预测风沙区工程堆积体土石质边坡次降雨侵蚀产沙量的最优选指标。研究结果可为工程堆积体土石质边坡侵蚀产沙预测提供一定的参考。     

浅谈大天池构造带五百梯气田水套加热炉热负荷

大天池构造带五百梯气田于1992年12月投入试采，于1997年正式投产。文章收集了五百梯气田一部分气井实际生产数据并进行计算，与原设计的计算参数及其结果作比较，总结出石炭系气藏天然气产量与流动温度的关系，并对水套加热炉热负荷进行了分析，为今后的设计提供参考。     

应用双头电导探针技术测量气液两相泡状流局部参数

本研究应用双头电导探针技术测量气泡局部参数,从而揭示了气液两相泡状流的内部流动规律。     

Effect of nonuniform sintering on mechanical and thermal properties of silica-based ceramic cores

During sintering of the silica-based ceramic core of turbine blades, a phenomenon called “nonuniform sintering” occurs that negatively affects the thermal and mechanical properties of the core. Standard samples of silica-based core were prepared by an injection molding method and sintered with alumina backfilling powder with different sodium contents. The effect of sodium content on the nonuniform sintering of silica-based cores and the thermal and mechanical properties was evaluated. Results show that the sintering level and the content of α-cristobalite in the surface layer are significantly higher than that of the sample interior. A considerable number of microcracks are found in the surface layer due to the β to α-phase transition of cristobalite. As the sodium content in the alumina powder decreases, the level of the nonuniform sintering and the amount of crystallized cristobalite in the surface layer decrease, which is beneficial to the thermal expansion and flexural strength at ambient temperature. The flexural strength and thermal deformation at high temperature are improved by reducing the surface cracks, but deteriorated with the decrease of the cristobalite crystallization when the surface cracks are macroscopically invisible.