油田采油输油状态检测智能单流阀研制

油田抽油机和输油管路大多分布在环境恶劣的野外,对采油输油状态进行实时监测一直是采油研究中的难点之一。为了防止油气倒流,单流阀大量用于输送管路中,研究中发现单流阀中的钢球运动与抽油机的工作状态和输油状态密切相关,依此提出并研制了一种通过检测单流阀中球体撞击管壁所产生的声音信号,并结合管道中原油的温度信息,检测采油输油状态的智能单流阀。同时,提出了一种典型采油输油状态检测判据,将采集到的声音与温度信号进行分析处理,实现了对常见采油输油状态的远程检测。实验结果表明,该检测装置可有效检测出抽油机正常工作、间歇出油、输油管路结蜡等典型运行状态,对远程实现采油输油状态检测具有一定的实用价值。     

Drop size measurements in electrostatic paint sprays

Drop-sizing experiments were performed on an electrostatic fan-spray atomizer operated in the airless mode. Tests were conducted with and without application of a high-voltage charge to the electrode tip placed downstream of the nozzle exit. A nonintrusive Malvern 2600 particle sizer, based on the forward scattering of a 5 mW He-Ne laser beam, was used to yield line-of-sight and cross-sectional drop size distributions. The atomizer was traversed across the laser beam, and drop size profiles as a function of distance from the centerline were developed. Enamel paint with a viscosity of 17 cp was sprayed over a differential pressure range of 1.38 to 6.20 MPa. Results indicate that at low injection pressures the charge application has a significant effect on the average drop size and the spatial drop distribution. However, as injection pressure is increased, the electrostatic influence on drop size and distribution decreases     

Interpretation and analysis of power quality measurements

This paper describes advances in power quality monitoring equipment and software tools for analyzing power quality measurement results. Power quality monitoring has advanced from strictly problem solving to ongoing monitoring of power system performance. The increased amount of data being collected requires more advanced analysis tools. Types of power quality variations are described and the methods of characterizing each type with measurements are presented. Finally, methods for summarizing the information and presenting it in useful report formats are described     

随钻电阻率测量系统响应模拟算法探讨

随着勘探地质目标的日益复杂和钻井自动化程度的不断提高,随钻电阻率测井技术已成为开发复杂油藏的关键技术,同时也对随钻电阻率测井仪器测量精度提出更高的要求。依据随钻电阻率测井仪器响应模拟得到的结果建立系统、准确的随钻电阻率测量资料解释理论,对开发高性价比的随钻电阻率测井仪器具有重大的意义。文章介绍了目前四种主要的随钻电阻率测井仪响应模拟算法：BCGS-FFT法、时域有限差分法、传输线矩阵法和有限元法,综合分析了它们各自的特点以及在该领域的应用情况,并展望了随钻电阻率测井仪器响应模拟研究的发展方向。     

N层土壤模型下HVDC系统大地回路运行时ESP分布研究

分析High Voltage Direct Current(HVDC)输电系统大地回路运行时地表电位分布,是评估地下金属管道腐蚀、变压器直流偏磁、通信干扰等不良效应受接地极电流影响的前提。文中利用镜像法和电磁波的折射、反射规律,推导出N层垂直和水平复合分层的地表电位的解析公式,然后利用这个解析公式解决华东地区地表电位分布的实际问题,通过不同模型计算结果的反馈得到华东地区理想的仿真模型,最后用多项式插值将电位曲线进行拟合,得到华东地区地表电位的一般函数表达式。     

Ozone generation in DC-energized electrostatic precipitators

Ozone emissions from a short wire-plate precipitator and three commercial electronic air cleaners were measured. Ozone generation was most strongly affected by the corona current and polarity of the discharge electrode. To a lesser extent, the type of corona (i.e. whether tuft or glow) was also important. Water vapor seems to reduce the ozone emission rate for negative corona, but ozone emissions from positive coronas are relatively unaffected. Ozone emission rate was also affected by the radius of the discharge electrode     

125 MW机组电除尘器的技术改造

介绍了株洲华银火力发电有限公司2台125MW机组电除尘器增效改造的方法和取得的良好效果,为在不动土建的情况下,将电厂电除尘器三电场改为四电场提供了参考经验。     

Determination of void fraction by electrically sounding two-phase flow

The main sources contributing to the error of the electric sounding method are analyzed, and a procedure for determining void fraction with a minimal error is presented.     

Applications of electrostatic stretch-and-positioning of DNA

The authors have previously reported that the electrostatic orientation and the dielectrophoresis (DEP) of DNA occur under ≈1 MHz, >1×10⁶ V/m field, by which DNA strands are stretched straight along field lines and positioned onto electrode edges. This paper presents some application of this stretch-and-positioning method to genetic engineering. It is shown that the DNA size distribution, as well as the activities of nuclease, can be determined by the measurement of the apparent length of stretched DNA. Several methods are developed to immobilize stretched DNA onto a substrate, including: (1) immobilization onto a conducting substrate for observations with the scanning tunneling microscopy, (2) anchoring onto a substrate only at both ends of the DNA using special electrode configuration, and/or molecular binding between avidin and biotin. The DNA can be held without contact to the substrate in the latter method, so that it does not cause steric hindrances to the DNA-binding enzymes. A novel fluid integrated circuit (FIC) device is proposed in which stretched DNA is cut by laser beam for the successive sequencing. A method to obtain unidirectionally oriented DNA is developed. The spatial resolution, and the small number of molecules required, are the advantages of the assays and measurements using electrostatic DNA manipulations over conventional biochemical methods. It is hoped that the methods may open a way to a novel category of “molecular biochemistry with spatial resolution.”     

Analysis of apparent resistivity in a multi-layer earth structure

An expression for the apparent resistivity in an earth structure with an arbitrary number of layers is derived for the Wenner four-electrode method. The expression is arrived at by performing an analysis of apparent resistivity in a multilayer structure as an extension of studies that have concentrated on the two-layer model. Applying a series of parameter data to this expression enabled the preparation of ρ-a curves for such a multilayer structure, and these curves were compared with actual ρ-a curves obtained from two case studies. The results showed good agreement, indicating that the proposed expression and parameter estimation technique could be practically applied to ground design problems. In particular, earth parameters for a multilayer structure obtained through the proposed method can be used for calculating the ground resistance required by deep-driven rods in a particular geologic formation     

Ultralow resistivity in the surface direction of LB heterofilms

LB heterofilms of double layer consisting of arachidic acid and 2-pentadecyl-7, 7′, 8, 8′-tetracyanoquinodimethane (C₁₅ · TCNQ) LB films were sandwiched between Al and Au thin evaporated films. Such layer structures of Al/LB heterofilm/Au were deposited on the SiO₂ insulating film of silicon wafters. Resistance in the surface direction of the above layer structure was measured by the four-point probe technique. As a result, very low resistance of 10^?2 ～ 10^?3 Ω was obtained by the electrode system of gap 3.3 mm with width 10 mm. It was clarified in the experiments that the current flowed through the LB heterofilms of about 200 ～ 30 Å in thickness; accordingly the resistivity of LB heterofilms was calculated to be 10^?8 ～ 10^?9 Ω cm. Such a value of resistivity was much smaller than the metal resistivity of 10^?5 Ω cm. Furthermore, the current through the LB film, increased up to 1.3A, was equivalent to the very high current density of 4.1 ～ 10⁵ A/cm². However, the resistance was increased suddenly by 10⁶ times at that time and the current was decreased to 3 ～ 10^?4 A. Such a switching phenomenon could be observed repeatedly. The ultraflow resistance and the very high current density observed in the LB heterofilms will be explained by the model of the potential well filled with electron gas which was generated in the LB hetero-film by the polarization of C¹⁵ · TCNQ LB film.     

Robust design of electrostatic separation processes

The aim of this paper is to analyze the robustness of the electrostatic separation process control. The objective was to reduce variation in the process outcome by finding operating conditions (high-voltage level, roll speed), under which uncontrollable variation in the noise factors (granule size, composition of the material to be separated) has minimal impact on the quantity (and the quality) of the recovered products. The experiments were carried out on a laboratory roll-type electrostatic separator, provided with a corona electrode and a tubular electrode, both connected to a dc high-voltage supply. The samples of processed material were prepared from genuine chopped electric wire wastes (granule size >1 mm and <5 mm) containing various proportions of copper and PVC. The design and noise factors were combined into one single experimental design, based on Taguchi's approach, and a regression model of the process was fitted. The impact of the noise factors could be estimated, as well as the interactions between the design and noise factors. The conditions of industry application of Taguchi's methodology are discussed, as well as the possibility of adapting it to other electrostatic processes.     

Electrical characterization of bell-type electrostatic paintingsystems

A numerical model that determines the electrical characteristics of a bell-type electrostatic painting system is presented. The model is capable of handling the complex geometries of practical sprayers and accounts for the space charge effect of charged paint droplets. The influence of aerodynamic forces is also considered in tracing individual droplet trajectories. As a test of tile simulation, the restricted case of a sprayer emitting ions, rather than charged paint droplets, was modeled. The simulation results were compared with experimental data and showed good agreement. For the more general case, maps of equipotential contours and the paint droplet trajectories are generated for a bell-type sprayer. It was found that the space charge tends to increase the deposition field, although not as strongly as increased bell potential or decreased bell-to-target spacing. However, the space charge also caused the spray pattern to expand, possibly leading to increased overspray     

Optimization of corona electrode position in roll-type electrostatic separators

The position of the corona electrode(s) is known to be a key factor of electrostatic separation efficiency, as it influences both the charging conditions of the granular materials on the surface of the roll electrode connected to the ground, and the magnitude of the electric forces exerted on the particles. Response surface methodology was employed for the design of the experiments performed on a laboratory roll-type corona-electrostatic separators, with samples of chopped electric wire wastes typically processed by such techniques. The results of the electrostatic separation tests are discussed in relation to the data obtained from two other experiments, in which corona current and particle charge measurements were performed for various positions of the standard wire-type electrode. The conclusions of this study enabled the formulation of several recommendations for the improvement of the outcome of industrial separation processes (i.e., maximize the weight percentage as well as the purity of the recovered materials).     

On electrostatic trapping of particle contamination in GITL systems

The insulation performance of gas-insulated transmission line (GITL) systems can be substantially affected by the presence and movement of contaminating metallic particles. The dynamics of wire and spherical particles in a coaxial-electrode system under AC voltage have been studied under different conditions. At voltages just above the lifting voltage the particle moved near the outer enclosure. Under appropriate conditions the particle can move into the high field region and eventually cross the interelectrode gap, thus causing a potential insulation hazard. Contaminating particles in a GITL system move randomly in the electric field. Control of contaminating particles is crucial for reliable operation of GITL systems. A numerical model of the contaminating particle's motion in the interelectrode gap in a GITL system was used to study particle control methods in gas-insulated power apparatus     

Design of electrostatic fields in a new monocomponent system

A method of designing electrostatic fields for the development of latent electrostatic images as used in a new monocomponent development system is described. This development system uses a development roller with a special structure in which a dielectric layer is formed on a conductive substrate, and a number of small independent electrodes are located on the surface of this dielectric layer. The system is capable of developing latent electrostatic images using only the high-spatial-frequency components of the latent electrostatic images for intensification so that reproduction of sharp line images and solid line images with broad-range density gradation is realized. This has been achieved by analysis of the electrostatic fields in a conventional development system, using a computer simulation based on the finite-element method. A variety of parameters in the system is determined so as to optimize the electrostatic field     

风机调速系统在静电除尘器中的应用

采用可编程逻辑控制器和变频器构成的风机调速系统可以使风机平稳起动,减小了起动时大电流对电网的冲击,延长了设备的使用寿命;同时能更精确地控制除尘器运行时电场内部的压力,有效避免压力波动剧烈,为除尘器的安全高效运行提供了保证。以某铝业公司沥青烟气净化静电除尘器风机调速系统为例具体介绍了系统设计、硬件选型、电路设计等,并对节能效益进行了评价。     

Ozone production in electrostatic air cleaners with contaminatedelectrodes

Runaway ozone generation due to contamination of electrode surfaces is a limiting factor in the long-term effectiveness of electrostatic air cleaners. Modification of the form of the corona discharge, accompanied by a significant rise in current, is the cause of increased ozone levels. After one week of operation in filtered air containing Arizona Road Dust, ozone concentration in a laboratory air cleaner increases by 460%. In this case, there is slight contamination on the discharge wires, but the ozone increase is attributed exclusively to back corona on the collection plates. On the other hand, oxidized discharge wires are believed to contribute to an order of magnitude increase in ozone concentration in a commercial air cleaner, operated in room air for 7 weeks. Wire contamination alone can increase ozone generation. An insulating tape adhesive applied to a 0.254 mm diameter stainless steel wire causes a 10-fold increase in ozone concentration     

电解地极在高土壤电阻率接地网中的应用

在高土壤电阻率地区,普通的降阻材料无法实现降低主接网电阻的目的,现采用获得国家实用新型专利证书、省级科技进步奖的DK-AG电解地极进行降阻处理。通过分析计算,确定所需电解地极的数量。方案实施后,检测实施的效果,达到满足电力系统主接地网的电阻要求。