流量测量的科里奥利流量计

本文介绍了科里奥利流量计的计量原理、详细分析了影响流量计准确度的各种因素,给出了影响仪表零点的原因。     

科里奥利质量流量计

本文叙述了科里奥利质量流量计的性能和应用范围,它在国内外的市场和技术发展情况。     

采用科里奥利质量流量计的流体粘度测量方法及影响因素研究

对流体在科里奥利质量流量计(以下简称科氏流量计)内的扭转运动状况进行了分析,得到运动速度与粘度的关系.通过对弯曲振动运动进行分析,结合流体运动及内摩擦力耗能情况,提出了一种新的粘度检测方法,导出了流体动力粘度与科氏流量计振动参数的关系,通过实验验证了方法的正确性.分析了影响粘度测量精度的部分因素.该方法简单、实用,拓展了科氏流量计的应用领域.     

科里奥利效应质量流量计

一、前言随着高科技的迅猛发展,流体介质的计量已被广泛地应用于货物的交易、内部结算和产品质量控制等各种场合。准确的流体计量对于一些领域内的现代化技术水平的提高,起着十分重要的作用,科里奥利质量流量计的问世,对于实现对各种流体介质,包括一些特殊流体的高准确度的直接质量流量的测量,具有十分重要的意义。     

科里奥利质量流量计Ω形测量管的有限元分析

振动测量管是科里奥利质量流量计的关键部件之一,其结构形状和尺寸大小直接决定着质量流量计的性能,为此本文针对Ω形科里奥利质量流量计给出了其工作原理和用有限元方法对其结构进行数值仿真的结果,同时还指出了在相同的几何尺寸、材料和环境条件下,Ω形管的响应模态比U形管的响应模态要低得多,因此在同样的条件下它具有更高的灵敏度.     

采用科里奥利质量流量计的流体黏度测量方法及装置设计

通过对弯曲振动运动进行分析,并结合流体运动及内摩擦力耗能情况,提出了一种新的黏度检测方法,导出了流体动力黏度与科里奥利质量流量计振动参数的关系,通过实验验证了方法的正确性.采用FPGA为主要器件,构成了黏度测量装置.该方法简单、实用,拓展了科氏流量计的应用领域,为其增加了一种新的功能.     

DFT方法处理科氏流量计信号中关键技术的研究

本文采用基于傅立叶变换的频谱分析方法,计算了流量信号的频率和相位差。介绍科氏流一计信号处理中测量初始化和频率跟踪等几个关键技术。     

应用PLD的一种新型科氏质量流量计的数字部分的设计与实现

本文介绍可用于测量流体流速、密度、流量等指标的一种新型科里奥利质量流量计及其数字部分的设计与实现.为了提高测量精度,减小硬件规模、功耗,使用了PLD(Programmable Logic Device)器件设计仪器电路,使测量精度达到1.2‰;数字部分仪器电路板缩小到90mm×160mm.仪器在实际应用中取得了较好的效果.     

科里奥利质量流量计在线连续测量流体密度的理论分析

科里奥利质量流量计是一种直接测量流体质量流量的仪表，同时可在线检测流体密度，出于对其传感器结构优化设计的目的，建立了振动微分方程，其解可给出流体密度在线检测的依据，并给出密度与温度的对应关系，得出给U型管谐振频率的推导结果，并进行具体计算的验证。     

环形科里奥利质量流量计的有限元分析

环形管是环形科里奥利质量流量计的关键部件之一,通过合理地选取环形管的结构形状和尺寸,可以使激振模态的固有频率与科里奥利力模态的固有频率很接近或相等,从而达到提高质量流量计的信噪比和灵敏度的目的.为此本文针对环形科里奥利质量流量计给出了其工作原理和用有限元方法对其结构进行数值仿真的结果,同时还指出了在相同的几何尺寸、材料和环境条件下,环形管质量流量计比U形管质量流量计具有更高的灵敏度.     

Experimental study on dynamic performance of coriolis mass flow meter and compensation technology

The Coriolis mass flow meter, for its features of directly measuring mass flow and high precision, is widely utilized in the flow measuring fields like batch filling and commercial trade. However, the unsatisfactory dynamic performance is one major constraint to Coriolis mass flow meter from being even more widely used in batch filling industry. To solve the problem, an experimental system which generates refined flow step stimulus signals for Coriolis mass flow meter was designed and based on which experimental and theoretical study on dynamic performances of typical Coriolis mass flow meter was carried out. On top of this, a time-domain recursive digital filter was designed to provide dynamic compensation and the experiments showed this filter can reduce the step response time of Coriolis mass flow meter by about 50%.     

A neural network to correct mass flow errors caused by two-phase flow in a digital coriolis mass flowmeter

Coriolis mass flow meters provide accurate measurement of single-phase flows, typically to 0.2%. However gas–liquid two-phase flow regimes may cause severe operating difficulties as well as measurement errors in these flow meters. As part of the Sensor Validation (SEVA) research at Oxford University a new fully digital coriolis transmitter has been developed which can operate with highly aerated fluids. This paper describes how a neural network has been used to correct the mass flow measurement for two-phase flow effects, based entirely on internally observed parameters, keeping errors to within 2%. The correction strategy has been successfully implemented on-line in the coriolis transmitter. As required by the SEVA philosophy, the quality of the corrected measurement is indicated by the on-line uncertainty provided with each measurement value.     

Orifice plate meter wet gas flow performance

Orifice plate meters are often used to measure wet gas flows. Research into the wet gas response of the horizontally installed orifice plate meter is discussed in this paper. Consideration is given to the significant influence of the wet gas flow pattern, as this has previously been found to be relevant to the wet gas response of other differential pressure type flow meters. A wet gas flow correlation for 2″ to 4″ orifice plate meters has been developed from multiple data sets from four wet gas flow test facilities. This corrects the liquid induced gas flow rate error for a known liquid flow rate to ±2% at a 95% confidence level.     

Performance evaluation of Coriolis mass flow meter in laminar flow regime

In many fluid flow applications, mass flow rate is preferred over volume flow rate, as it is more beneficial in terms of cost and material balance calculations. Coriolis mass flow meter (CMFM) is accepted widely for mass flow measurement owing to its accuracy and reliability. However, it has been found to under-read the mass flow rate in laminar flow region [1], thus limiting its application in this region. The secondary flow in the curved tube section influences the generated Coriolis force and leads to a deviation in meter readings. Commercial CMFMs are available with various curved tube configurations and need to be analyzed for their application in laminar region. This paper presents comprehensive experimental and numerical investigations performed to evaluate the influence of tube configuration and other meter parameters, such as drive frequency, amplitude of vibration, and sensor position, on the performance of the CMFM in laminar region. The findings of this study have put forth a suitable combination of tube configuration, drive frequency, and sensor position while using the CMFM in laminar flow regime.     

质量流量计在油田OGM计量站的应用

本文介绍了质量流量计在油田OGM计量站生产测试计量中的应用,对OGM计量系统做了概述,阐述了质量流量计的选用和含水计算测量方法,分析了对含气/含砂对质量流量计的液体流量测量和含水测量的影响,提出了解决措施,并结合实际应用提出了质量流量计选型中应注意的问题。     

Sheathed probe thermal gas mass flow meter heat transfer analysis

The thermal gas mass flow meter is an important meter used in industrial measurement. When the environmental temperature changes, the measured gas physical parameters change correspondingly and the thermal gas mass flow meter output signal is affected, causing large measurement error. The influence of gas temperature on the sheathed probe measurements is analyzed in this paper based on experiments and heat transfer theory using a three dimensional probe and gas heat transfer mathematical model based on the heat conduction equation. The probe heat transfer process is analyzed under convection heat transfer coupling conditions. The experimental data were analyzed and compared against the theoretical results, with a maximum average relative error of only 4.56%. The rationality of the theoretical method is thus verified.     

Design method for flow tube structure of electromagnetic water meter with shrunk measurement tube based on pressure loss-flow restriction

Due to the low flow rate measurement demand for battery-powered electromagnetic water meter, shrunk measurement tubes (such as circular section transition to square section) are often used to enhance flow velocity and measurement performance at small flow rate. However, this will also result in an increase in sensor pressure loss, even exceeding the pressure loss limit. Therefore, it is necessary to study a flow tube structure design method based on pressure loss-flow restriction, and design a flow tube structure which can not only maximize the induced voltage, but also meet the actual pressure loss requirement. Because there are many unknown variables in the formula of pressure loss mechanism, it cannot be directly used in structural design. Therefore, taking DN100 sensor as an example, based on finite element software, the variation of pressure loss with the length, width and height of rectangular section is obtained by orthogonal test method, and the numerical model of pressure loss is established. According to the requirements of industry and induced voltage enhancement, the optimal rectangular section size is found with the established pressure loss numerical model, and the structure of flow tube transition section is further optimized to reduce pressure loss. Finally, the prototype is made according to the optimized structure. Pressure loss experiment shows that the error between simulated value and measured value is within ±2.68% (±0.4 KPa). It means the pressure loss-flow restriction based design method for flow tube structure of electromagnetic water meter with shrunk measurement tube is effective and reliable.     

Modeling of Coriolis mass flow meter of a general plane-shape pipe

The vibration of a general plane tube with a flowing fluid, which is the measuring element in a Coriolis mass flow meter (CMF), is studied. The dynamic stiffness matrix method is used to model such a tube. The tube is divided into straight and circular elements. The elements dynamic stiffness matrices are derived from the equations of motion. By assembling the elements matrices into a global matrix the natural frequencies are obtained. The mode shapes are obtained by applying the boundary conditions at the supports and the compatibility conditions at the nodes. The effects of the flow velocity on the natural frequency and the relative phase difference are modeled. The method is applied to different tube shapes. The results are compared to the published data which reveals good agreement.     

Calculation of the sensitivity of a straight tube Coriolis mass flowmeter with free ends

The weight vector theory for Coriolis mass flowmeters is applied to a simple theoretical meter configuration consisting of a single unsupported straight tube unattached to adjacent piping. The tube has free ends and vibrates in the fundamental mode. It is shown how the sensitivity of this meter depends in part on the interaction of the flow velocity profile with fluid vibrations occurring near the tube ends. This end effect is negative i.e. the meter reads lower than would be expected if end effects were ignored. On account of the end effect there is a predicted variation in sensitivity with Reynolds number (of the order 1% in a tube 25 diameters long) and this can be minimised by a certain choice of the sensor positions.     

A finite element model for the analysis of flexible tube Coriolis mass flow meter using first order shear deformation shell theory

The numerical modelling of Coriolis Mass flow Meter (CFM) is essential for predicting its outcomes accurately in terms of sensitivity as well as exact mass flow rates. In the majority of mathematical and numerical modelling concerning the flexible structures, the authors neglect the dimensional and shape variation of the structure due to self-weight. The shell based on the First-order shear deformation shell theory (FSDST) is preferred in modelling shells compared to the beam model. The current work includes numerical modelling of CFM using eight noded isoparametric shell elements and twenty noded Acoustic fluid elements. The fluid energy describes as the potential, and the dynamic boundary condition is assumed utilising the displacement of structure and potential of the fluid. The fluid dynamic equation combining suitable numerical model, fluid-structure interaction module and cross-correlation technique helps to achieve the numerical modelling of CFM. The numerical model of CFM utilises the Newmark Beta method of numerical integration, and the response of two equidistant locations from the point of tube excitation is acquired. For the flexible tube conveying fluid, there exists sagging of tube due to the weight of tube and fluid. The Coriolis force and the external excitation force cause the fluid conveying tube to bend and twist, and as a result, the velocity responses picked from two equidistant points shows a difference in phase. The effect of sagging leads to a lower phase shift and time decay, and hence the sensitivity of the CFM is low for low pre-stretched flexible tubes. The pre-stretching of flexible tubes reduces the effect of sagging, facilitates to regain the cylindrical shape of the tube and increases the sensitivity of CFM. The result reveals that the shell element along with the three-dimensional acoustic fluid element provides the most accurate numerical model for the CFM and the change in sensitivity, as well as the change in mass flow measurements, can appropriately be analysed with the help of this numerical model. The amplitude of the velocity of the structure, measured from the two equidistant points, shows a difference. The severe variation in amplitude of velocity measured from two points is an implication of the out of plane deflection of the tube. For a CFM made up of metal tubes, the amplitude of velocity variation is minimal and ignored by the authors.