基于半透膜的钻井液油气分离检测技术

在钻井过程中,录井对钻井液油气的检测是发现和评价油气层重要手段之一,定量获取油气组分信息是有效评价油气层和油气性质的基础.目前录井气测技术所检测的烃组分通常由电动脱气器获得,受钻井液温度、液面高度和黏度的影响较大,所获得的油气定量信息较少,影响了油气解释与评价的准确性.半透膜对油气具有选择性分离的特性,能直接从钻井液中获取烃类组分,能够为油气解释与评价提供定量的基础信息.通过对半透膜和气体分离技术的研究,制备适合现场油气分离要求的半透膜,并在此基础上研制了半透膜油气分离装置,通过稳定性和灵敏度、耐温和抗冲击性能试验,以及钻井现场的应用,其结果证明了该半透膜钻井液油气分离装置适用于钻井现场的油气检测,扩展了油气检测内容,丰富了油气评价信息.     

Modeling of a ferromagnetic two-dimensional electron gas device

We present a realistic modeling of ballistic electron transport in a hybrid ferromagnetic (FM) two-dimensional electron gas (2DEG) device, consisting of an FM gate on an AlGaAs-GaAs or AlSb-InAs high electron mobility transistor (HEMT) heterostructure. The carriers within the 2DEG are spin-polarized by a combination of magnetic and electrostatic barriers. The magnetic barriers are supplied by a composite FM gate, consisting of two domains made of magnetically hard and soft materials. This gate arrangement breaks the antisymmetry of the fringe B field, and results in a finite spin polarization of the 2DEG current. The B field strength is calculated by considering the pole strength at the gate surfaces and domain boundary, and is significantly weaker than normally assumed. We obtain parameters such as the electrostatic barrier height, Fermi level, and carrier concentration within the 2DEG by a finite-element Poisson calculation, which is self-consistent with the Fermi-Dirac distribution. We calculate the transmission probability and conductance through the 2DEG from these parameter values, assuming a single particle effective mass Hamiltonian and purely ballistic transport. We show that the spin polarization ratio P/sub G/ is extremely sensitive to the gate bias and HEMT doping concentration. However, the maximum P/sub G/ is extremely low for AlGaAs-GaAs (0.003%) and even for AlSb-InAs (0.12%) devices, despite a large Lande g factor. These values are many orders of magnitude smaller than previous predictions of close to 100% polarization, obtained by using simpler models.     

Magnetic fluid seals eliminate emissions from gas handling process equipment

With increasing worldwide environmental concerns, rotating equipment manufacturers and users are closely evaluating sealing technologies which allow them to meet dramatically reduced sealing limits in an effort to control fugitive emissions. Magnetic fluid sealing technology, with the benefits of zero-leakage and low installation/maintenance costs, is being installed on gas handling equipment to help users to meet these new environmental regulations.     

mt法天然气流量标准装置软件设计

随着科学技术的发展，以及国家新的计量标准相继出台，基于老版本标准开发的原有软件已反映出某些不适应。为适应我国加入WTO后流量测量与国际接轨的形势，确保标准软件与先进标准同步，保持其先进性，对mt法天然气流量标准装置进行技术改造、升级已迫在眉睫。本文介绍了眦法天然气流量标准装置的工作原理，并详细叙述了采用VB结合数据库开发计量软件的过程。     

Design and demonstration of a switching engine for a binary true-time-delay device that uses a white cell

Optical true-time-delay devices based on the White cell can be divided into two general types: polynomial cells, in which the number of delays that can be obtained is related to the number of times m that a beam bounces in the cell raised to some power, and exponential cells, in which the number of delays is proportional to some number raised to the power of m. In exponential cells, the topic to be addressed, the spatial light modulator switches between a delay element and a null path on each bounce. We describe an improved design of this switching engine, which contains a liquid-crystal switch and a White cell. We examine astigmatism and corrections for it and present a specific design.     

Analysis of a convective fluid flow with a concurrent gas flow with allowance for evaporation

The paper presents a theoretical analysis of a convective fluid flow with a concurrent gas flow accompanied by evaporation at the interface. The analysis of two-layer flows is based on a mathematical model taking into account evaporation at a thermocapillary boundary and effects of thermal diffusion and diffusion heat conduction in the gas–vapor layer. New exact solutions describing steady two-layer flows in a channel with the interface remaining undeformed and examples of velocity and temperature profiles for the HFE-7100 (liquid)–nitrogen (gas) system are presented. The influence of longitudinal temperature gradients along the channel boundaries, the gas flow rate, and the height of the fluid layer on the flow regime and evaporation rate is studied. A comparison of the calculated data with experimental results is performed.     

膜式燃气表检定装置在线校准技术研究

针对传统参数分项组合法难以实现对膜式燃气表检定装置直接、准确校准的问题,提出一种基于气体质量守恒原理的在线动态校准方法,研制了一套移动式主动活塞气体流量校准器,介绍了该校准器的结构和工作原理、在线校准系统架构及数学模型.对G1.6-4型临界流喷嘴式膜表检定装置进行了在线动态校准实验测试.实验结果表明,该方法能够真实反映检定装置的体积示值精度,方便修正,从而有效提高检定装置扩展不确定度至0.3%(k=2),进而为膜式燃气表检定装置的在线校准提供了解决方案.     

Guidelines for fluid modeling of dense gas cloud dispersion

Fluid modeling experiments can predict the behavior of complex dispersion phenomena associated with the dilution of flammable or toxic dense gases after inadvertent release. Such studies are desirable because variables can be controlled at will with great savings in time and expense over full-scale tests. The reliability and value of fluid modeling experiments will depend upon proper applications of similitude laws, the selection of appropriate instrumentation and test facilities, and the documentation of the results. This paper proposes guidelines for future fluid modeling expernnents of dense gas cloud dispersion. Performance envelopes are presented which bracket the “safe” regions in similitude parameter space for reliable model results. Recommendations are made for a minimum experimental program and associated documentation.     

The thermocapillary migration of gas bubbles in a viscoelastic fluid

The steady thermocapillary flow of a spherical bubble in a linear temperature field is analyzed by considering that the continuous phase is a weak viscoelastic fluid. Convective heat and momentum transfers are neglected but the action of gravity is taken into account. The problem is formulated for non shear thinning elastic fluids which may be described by the Olroyd-B constitutive equation. The analysis is restricted to weak elastic fluids, an assumption that in dimensionless terms is equivalent to assuming that the Weissenberg number Wi=λ/t_c where λ is the relaxation time of the fluid and t_c the scale time of the flow, is small compared to unity. Thus, the corresponding boundary value problem is solved following a perturbation procedure by regular expansions of the kinematic and stress variables in powers of Wi (retarded motion expansion). Velocity fields as well as the force exerted by the fluid upon the bubble are determined at second order in Wi. It is shown that when the motion is driven by buoyancy in the presence of surface tension forces of a comparable order of magnitude, the velocity fields are strongly affected. Unlike the newtonian case where the recirculation region generated is symmetrical, in a non-newtonian fluid elastic effects produce a breaking of symmetry, so that this region is enhanced and shifted in the downstream direction. The analysis also provides the second order correction to both the terminal velocity and the temperature gradient needed to hold the bubble at rest.     

The thermocapillary migration of gas bubbles in a viscoelastic fluid

The steady thermocapillary flow of a spherical bubble in a linear temperature field is analyzed by considering that the continuous phase is a weak viscoelastic fluid. Convective heat and momentum transfers are neglected but the action of gravity is taken into account. The problem is formulated for non shear thinning elastic fluids which may be described by the Olroyd-B constitutive equation. The analysis is restricted to weak elastic fluids, an assumption that in dimensionless terms is equivalent to assuming that the Weissenberg number Wi=λ/t_c where λ is the relaxation time of the fluid and t_c the scale time of the flow, is small compared to unity. Thus, the corresponding boundary value problem is solved following a perturbation procedure by regular expansions of the kinematic and stress variables in powers of Wi (retarded motion expansion). Velocity fields as well as the force exerted by the fluid upon the bubble are determined at second order in Wi. It is shown that when the motion is driven by buoyancy in the presence of surface tension forces of a comparable order of magnitude, the velocity fields are strongly affected. Unlike the newtonian case where the recirculation region generated is symmetrical, in a non-newtonian fluid elastic effects produce a breaking of symmetry, so that this region is enhanced and shifted in the downstream direction. The analysis also provides the second order correction to both the terminal velocity and the temperature gradient needed to hold the bubble at rest.     

Experimental considerations on a new automatic cooling device using temperature-sensitive magnetic fluid

An automatic cooling device to eliminate the waste heat of machinery has been made by utilizing a temperature-sensitive magnetic fluid. This cooler requires no pump for flowing the fluid, since a part of the thermal energy is converted to the kinetic energy. If a permanent magnet is used, power supply is unnecessary. The cooler is expected to be maintenance-free and simple in shape.     

气体大流量标准装置的扩展不确定度评定

本文根据《测量不确定度评定与表示》（JJF1059-1999）中的规范化要求和有关数据,对国家原油大流量计量站成都天然气流量分站的气体大流量标准装置的测量不确定度进行了评定,结果表明该装置经过技术改造后的扩展不确定度不大于0．05％（P=0．95）。同1996年装置建立时的扩展不确定度0．1％（P=0．95）相比,又进一步提高了测量准确度。     

Study of pressure drop pulsations in a standard orifice device of measurement systems for natural gas

In order to analyze the properties of pulsating flows in natural gas measurement systems, using standard restricting devices, studies are performed for amplitude-frequency spectra of pressure drop pulsations at an orifice device under operating conditions. __________ Translated From Izmeritel’naya Tekhnika, No. 6, Pp. 44–49, June, 2006.