包含电极尺寸及位置信息的电磁流量计干标定模型

现有电磁流量计干标定模型中,电极尺寸、位置均被作了理想化处理,即假设电极尺寸无穷小、电极位于测量管段正中间的两个对称点上,两对称点连线与磁场垂直。这类理想化的模型与实际情况差异较大,限制了干标定的精度,并对产品一致性提出了很高的要求。针对这一问题,采用分离变量法建立了包含实际流量计电极尺寸及位置参数的电磁流量计干标定模型,比现有干标定模型更接近于实际流量计,有利于提高干标定精度,降低对产品一致性的要求。通过与现有模型及数值仿真的对比分析,验证了该模型的准确性。     

一种大口径电磁流量计的单位元标定方法

针对传统大口径电磁流量计实流标定成本高的问题,提出用小测量管作为单位元的低成本标定方法。以微元理论为基础,将整个流量计测量区域划分成若干个轴向子空间,用小测量管逐个测量各个子空间的感应电动势,提取其有效特性信息,重构后得到整个流量计空间的特性分布,有效解决实流标定带来的成本过高问题,为大口径电磁流量计的低成本标定提供一种有效的方法。重点对零点漂移下小测量管的感应电动势、装置系数和仪表系数的关系进行研究分析,并给出标定系数的最终表达式。用实流标定法和单位元标定法进行简单的标定比对试验,结果表明单位元标定法的准确度等级为0.5级,具有一定的可行性。     

HB3603系列电磁流量计的研制

为进一步提高电磁流量计的应用范围及测量精度,研制了HB3603系列电磁流量计,介绍了该系列流量计的工作原理及关键设计技术.该系列流量计具有结构合理、功能齐全、测量准确等技术特点,可广泛应用于各类工业现场.     

电磁流量计在酸性废水处理中的应用

介绍Khrone公司生产的电磁流量计在不锈钢酸性废水处理中的应用,探讨了电磁流量计的测量原理和结构,以及安装技术要求和常见的故障,对于掌握该流量计的使用方法和性能具有一定的指导作用,为电磁流量计在线测量提供了一定的参考。     

双激励电磁流量计的研究

在对电磁流量计技术的不断研究中认识到,电磁流量计传感器具有电极与导电流体间的特有关系,可以引入一个电压激励下的新的阻抗分压测量关系,使电磁流量计传感器在磁场与电压两种激励下以交替方式工作,组成两个参数的测量关系,形成一种新型的双激励电磁流量计。     

用于石油测井的连铸机电磁流量计误差分析

针对石油测井用连铸机电磁流量计在测量混合流体时存在较大误差的问题,开展用于石油测井的连铸机电磁流量计误差研究。分析连铸机与连铸机电磁流量计结构原理,设计连铸机电磁流量计误差补偿算法。校准组分流体中连铸机电磁流量计参数,得到改变组分后流量计的校准数据,引入最小二乘法拟合连铸机电磁流量计特征曲线,输出信号的组分补偿系数,应用到连铸机电磁流量计特征曲线补偿中,实现特征曲线实时补偿。实验结果表明,所提方法测量误差绝对值与附加误差能够始终保持在2%以下,证明该方法能够有效降低测量误差和附加误差,测量效果较好。     

高温低功耗电磁流量计的研制

通过对电磁流量计测量技术发展的分析，认为如从小型、低功耗和高温作为切入点，通过特殊设计的磁场结构，多参数测量等手段和方法将是对电磁流量计的创新。以此思想设计并制造出了一种主要用于油田注水井注水流量测量的新型流量计。     

电磁流量计的智能化

电磁流量计的智能化开封仪表厂张稚，韩书芳智能化电磁流量计是一种以计算机技术为核心的自动测试系统（ＡＴＳ）。有显示数字化、计算与控制软件化和运行参数可编程及以下特点：１．提高励磁技术水平，改善测量性能励磁技术是衡量电磁流量计测量性能的关键技术之一。电磁...     

非满管电磁流量计在污水测量中的应用

环境保护是我国的基本国策之一,工业污水的计量越来越引起重视.该文介绍了一种新型的专为非满管状态下的流量测量而设计的流量计,简单介绍了非满管电磁流量计的测量原理,着重描述了其独特的电容液位测量系统,分析了非满管电磁流量计在污水测量应用中的特点及优势.     

电磁流量计干扰分析与对策

根据电磁流量计的测量原理,结合电磁流量计实际应用中遇到的正交干扰、微分干扰、工频干扰等问题,分析干扰产生的原因,提出采用同步采样技术、采样时间长度选择、数字滤波技术等方法,从根本上对这些干扰信号进行抑制和消除,使电磁流量计更适应于现场应用。     

A technique for low cost calibration of large electromagnetic flowmeters

The need for calibration of electromagnetic flowmeters adds considerably to the cost of these instruments especially in the larger sizes. This paper discusses a proposed technique for calibration of large electromagnetic flowmeters which avoids the need for a calibration flow rig. The technique consists essentially of filling the flowmeter tube with water, operating the electromagnet as it would be operated in normal flowmeter operation and measuring the axial component of the eddy current electric field in the water over each electrode. This allows the calibration factor for a flat velocity profile to be determined.     

差压式湿气两相流量计的校准

伴随着工业技术的不断发展,湿气流量的测量日益增多,湿气流量计的校准工作日益迫切,亟待解决。本文介绍了在湿气流量计量领域中广泛应用的差压式湿气两相流流量计的原理,并在天津大学电气与自动化工程学院的中压闭环湿气标定装置中对其进行了校准,对该流量计的气相和液相的不确定度进行了评定,为今后开展相关流量计的校准工作提供了参考和数据支持。     

Electromagnetic flow meters for open channels: Current state and development prospects

Electromagnetic method to measure water flow has been known for nearly 180 years. This paper presents how the method has undergone development and describes in detail the most common electromagnetic flowmeters used for open channels. It also presents specific methods of signal processing used in this type of flowmeters. The analysis is associated directly with the relevant types of induced magnetic field. Some of the analyzed types of magnetic fields considered are sine waves and bipolar rectangular fields. The concept of low-energy electromagnetic flow meter was introduced as part of deliberations concerning current development trends.     

Theoretical study of vertical slug flow measurement by data fusion from electromagnetic flowmeter and electrical resistance tomography

Electrical resistance tomography (ERT) can be used to obtain the conductivity distribution or the phase distribution of gas/liquid flows (e.g. slug flow). Using proper parameter models and flow regime identification models, the measurement of phase size, void fraction, and pattern recognition can be realized. Electromagnetic flowmeters have been used to measure conductive single-phase liquid flows. However, neither ERT nor electromagnetic flowmeters (EMF) can provide accurate measurement of gas/liquid two-phase flows. This paper presents an approach to fuse the information from ERT and an electromagnetic flowmeter. A model for the measurement signal from the electromagnetic flowmeter has been developed based on the flow pattern and the phase distributions, which are obtained from the reconstructed images of ERT, aiming to reduce the measurement error of the electromagnetic flowmeter and enhance the measurement accuracy. Through the simulation research of virtual current density distribution, the feasibility of fusion of electromagnetic flowmeter and ERT to measure gas/liquid two-phase vertical slug flow is verified. By theoretical analysis, the relationship between the output of electromagnetic flowmeter and flow parameters is established. The electrical potential difference of the electromagnetic flowmeter, average velocity, volume flow rate and gas void fraction between the bubble size and location are also investigated. The fusion approach can be used to measure vertical slug flows.     

分布式电磁接收系统多频标定信号的产生与检测

为了提高分布式电磁接收系统频域标定的效率和精度,提出了一种基于多频伪随机信号的标定方法并研究了多频标定信号的产生和标定数据的处理方法。首先,根据多频伪随机信号的解析式分析了其主频点的振幅和分布特点,通过现场可编程门阵列(FPGA)实现了伪随机信号的编码合成并产生了高精度双极性标定信号源。然后,基于相关检测的噪声抑制原理,给出了检测含噪声多频标定输出信号幅度和相位的多次相关迭代法并通过仿真进行了验证。最后,对分布式双通道电磁接收系统的采集通道和磁场传感器进行了标定测试。结果表明:在外界噪声不大于标定输出信号幅度的环境下,检测结果幅度误差小于2%,相位误差小于1°。该标定方法快速准确,可用于分布式电磁接收系统在不同野外环境下的频域标定。     

Invariant system for measuring the flow rate of wet gas on Coriolis flowmeters

One of the important tasks of modern flow measurement is to measure the flow rate and the amount of wet gas. This task becomes especially important when there is a need to obtain information about the amount of dry gas at the production facilities. The paper presents the principle of operation and structure of the invariant wet gas measurement system. The work of the invariant flow measurement system is based on the application of the principle of multichanneling and the method of partial flow measurement. Coriolis flowmeters are used as the main elements of the system. The proposed measurement system does not imply the use for gases with abundant droplet moisture. The authors propose a method of verification of the measurement system, which is currently limited by the measurement error of moisture in the gas equal to 5%. The article also provides information on the results of the test of the system.     

Study of acoustic transducer protrusion and recess effects on ultrasonic flowmeter measurement by numerical simulation

In order to improve the measurement performance of dry calibration on ultrasonic flowmeter, the Computational Fluid Dynamic (CFD) modeling approach of the effect on transducer protrusion and recess are mainly discussed in the paper while its effects on ultrasonic flowmeter accuracy are also presented. Through comparing simulation results to experimental data, the CFD modeling is firstly determined. Then, detail analysis on flow field for two typical transducer installations are obtained based on the CFD method. Besides, the mechanism of both flow effects on measurement accuracy are explained and compared respectively, which indicates that negative velocities generated at protrusion and recess locations are the indispensable factors for negative measurement errors. Finally, comparison results show that smaller measurement error can be achieved with protruding transducers, which is a better arrangement type of transducer for ultrasonic flowmeters.     

Evaluation of flowmeters for heat metering

Heat flowmeters are expected to be reasonably priced, be very reliable, and have high measurement accuracy. Various types of heat flowmeters have been developed and they are widely used in large residential and industrial buildings. In this study, three types of heat flowmeters (turbine, electromagnetic and ultrasonic) were tested for accuracy, effect of installation position and vibration, durability and performance in the field for several installation positions and in the presence of vibration. We used a liquid flow standard system and a customized durability test system in accordance with the International Organization of Legal Metrology (OIML) R 75-2 heat meter testing method. The field test was conducted in eight different locations from winter to summer. All flowmeters were calibrated before and after the field test, and the measurement deviation and the relative expanded uncertainty were calculated. The mean deviations obtained were–0.21%,–0.07%, and 0.11%, with the relative expanded uncertainties 0.48%, 0.17%, and 0.40% for turbine, electromagnetic, and ultrasonic flowmeters, respectively. The results of position and rotation tests, mean deviations by rotation angles at 90°, 180°and 270°relative to 0°(horizontal position) were–1.24%,–1.07% and–0.80%, respectively. For the vibration tests at 1 m/s² and 5 m/s² vibration acceleration, the turbine flowmeter, the electromagnetic flowmeter and the ultrasonic flowmeter showed deviations that ranged from −0.2% to −0.5%, −0.6% (2.6 m³/h), and 0.0% (negligible), respectively. In the durability tests, the accuracy of all three types of heat flowmeters remained at ±1% or less, showing sufficient durability. In the field test, the deviation of the turbine flowmeter and the ultrasonic flowmeter showed ±2.5% or less deviation. However, the electromagnetic flowmeter seems to be inaccurate below 6.9% of the maximum flow rate.     

二维回归分析法在电磁辐射测量误差中的应用

分析温度在电磁辐射测量中的影响。通过重复性温度实验和二维回归分析法,分析了温度变化与用磁场探头测量的磁感应强度的关系,得到了计算磁感应强度的二维回归方程。结果表明,通过二维回归方程所得的计算结果与标定值吻合较好,减少了温度变化给测量带来的误差,同时通过温度补偿能提高电磁辐射测量的精度,结果能准确地反映电磁辐射的真实大小。