基于电导法的原油含水率测量改进方法

基于电导法开展原油含水率测量具有硬件结构简单,系统稳定可靠及测量准确等特点。根据Maxwell模型原理,电导法测量原油含水率需要获知纯水相电导率。然而,开展井下实时含水率测量时,纯水相电导率无法直接测得,直接使用预设的纯水相电导率无法真实得出井下原油的实时含水率。鉴于此,本文根据原油的馏分性质,通过测量不同温度下两组油水,混合相的电导率值并进一步推导得出原油含水率表达式,规避纯水相电导率测试问题及预设纯水相电导率不精确问题,实现对现有原油含水率测量方法的改进。基于ARM Cortex M4处理器及多种传感器测量技术开展了实验研究.实验结果表明,当测量含水率大于90％的油水两相流时,误差可在２％以内。当测量纯水相矿化度在7g/L以内的油水两相流时,含水率误差基本不受矿化度影响。实验结果验证了优化方法理论的有效性,具有实际应用的可行性。     

油水两相流流型的混沌时间序列分析

采用一种基于互信息第一极小值计算法确定了相空间重建延迟时间,用Mackey-Glass方程及Lorenz奇异吸引子数据作算例检验了该计算方法的可靠性．通过计算的混沌吸引子关联维对油水两相流流型进行了表征,结果表明对含水率为61％～91％及总流量为10～60(m^3／d)的水包油流型,油水两相流电导波动信号的关联维与含水率及总流量有着良好的相关关系,而对含水率为51％的油水两相流过渡流型,关联维随总流量呈现不规则突变,表明了混沌吸引子关联维数对油水两相流流型变化具有敏感的“指示器”特性．     

基于电容层析成像技术的两相流可视化测量仪器

针对油水两相流参数测量问题,依据二重积分微元原理建立了油水两相流分布信息的数学模型,采用一种具有抗杂散电容的测量电路和80C32单片机完成了极板间电容的测量和采集系统的控制,组建了一套8电极油水两相流电容层析成像测量系统,系统采用了自适应阈值的图像重建的方法完成了油水两相流的截面图像的重建和油水两相流含水率的计算,其重建精度在1%左右,满足了油水两相流流型识别的要求,为油水两相流参数的可视化测量提供一种新方法.     

水平油水两相流测井仪器测量通道内流型识别

水平井产出剖面测井中集流型仪器内油水两相流流型通常呈复杂多态性,正确认识流型演化规律有助于井下流量测量精度提高．在油水两相流流动环路中采集电导及电容传感器波动信号的基础上,基于非线性时间序列递归图纹理分析方法,对集流型仪器内油水两相流流型特征进行了表征,研究发现：在不同流量及含水率下,递归图纹理特征与流型之间具有较好的对应关系,可通过递归图纹理特征有效识别水平油水两相流流型．     

原油含水率测量多因素影响的数值模拟与实验研究

基于介电常数法测量原油含水率,往往受油水两相流态、温度、矿化度、非线性特性等多因素的影响.因此,设计一套基于多传感器的油水两相流实验室模拟系统,利用理论计算结合数值模拟的方法,研究含水率、温度、矿化度、油水介电常数、含水测最传感器输出之间的数学关系及影响规律,对提高测量含水率的精度提供了有力的理论和实验依据.     

电导式相关流量测量传感器

在油水两相流条件下,水为连续相时,电导式传感器利用油相分布的离散性所造成的流体阻抗的随机变化检测流体流动噪声,通过对传感器中的上、下游传感器所检测出的流体流动噪声进行互相关运算,得到和流体流量相关的渡越时间,该传感器用于井下油水两相流量测量。文中给出了相关流量测量用电导式传感器检测流体流动噪声的原理、传感器中敏感器的结构及设计原则,同时给出了传感器激励源及信号处理电路的设计原则,文中最后给出了电导传感器在多相流模拟井上的流量测量实验及分析。     

集流型流体电容仪测量井下油水两相流的含水率

对集流型流体电容含水率计在井下油水两相流高含水时应用的可行性进行了研究。建立了泡状流、水为连续相时传感器的等效电路模型。该模型认为在泡状流、高水矿化度、水为连续相的情况下，传感器只敏感于碰撞到内电极绝缘介质层上的油滴。在通常的测量条件下，传感器仍具有较高的灵敏度。为验证理论的正确性，设计了四个静态实验，并进行了模拟井动态实验。实验结果与理论预测完全一致。     

电容层析成象技术在两相流流型辨识中的应用

以１２电极电容层极成象（ＥＣＴ）系统所重建的管截面图象为分析对象,从图象理解的角度出发,采用图象的树型拓扑结构表示和模糊模式识别技术辨识两相流流型,为分相含率测量等提供先验知识。该方法可识别层状流、环状流,核心流等两相流型。     

微波透射法测量含水率的研究

基于微波透射法,设计了一套液液两相流(其中一相为水)的中高含水率测量系统,该系统与现有方法不同之处在于系统中设计的传感器减小了干扰效应,适于测量中高含水率液液两相流.根据测量介质合理选择测量频率,对实验数据曲线拟合,获得测量经验公式.实验结果表明:设计的装置可对含水率为30%～75%的液液两相流进行有效测量;采用测量经验公式,其测量精度高于5%.     

基于弧状电极传感器的气/水两相流参数测量系统设计

气/水两相流流动参数的检测对工业过程的控制和优化有重要意义,相含率作为一个重要参数直接影响到两相流建模的精度。为测量两相流相含率参数设计了弧状电极电导传感器测量系统,通过对气/水两相流典型流型的物理模拟研究了相含率与测量电压之间的关系。实验结果表明:弧状电极电导传感器的液相相含率与测量电压存在很好的线性关系,为两相流动态实验参数测量提供了依据。     

Oil holdup prediction of oil–water two phase flow using thermal method based on multiwavelet transform and least squares support vector machine

Oil holdup of oil–water two phase flow (OWTPF) was measured using thermocouple based on the thermal method. A new model based on least square support vector machines (LSSVM) and multiwavelet transform has been proposed for the first time, which is capable of forecasting oil holdup of oil–water two phase flow. The temperature signal of OWTPF is greatly disturbed by noises from external interference, which results in a limited measurement range of oil holdup. In order to solve the problem, a new signal processing method based on the multiwavelet transform is used. Multiwavelet transform has several scaling functions and corresponding wavelet functions, which can simultaneously achieve orthogonality, symmetry. With ideal performance, noises were removed and actual temperature signal was effectively retained. The fluctuated amplitude signal denoised and total flux of OWTPF were employed as inputs and the oil holdup was used as output of LSSVM model. In order to improve the predictive accuracy and generalization ability of the LSSVM model, a Genetic Arithmetic (GA) has been adopted to determine the optimal parameters of LSSVM model automatically. The experiment results indicate that the performance of LSSVM–GA model outperforms those of artificial neural network (ANN), LSSVM–GA model can be used for estimating the oil holdup of OWTPF with reasonable accuracy.     

超声法测量气固两相流传感器选取研究

超声法因其穿透性好、精度高等优点成为气固两相流参数检测的一个新趋势.由于超声波在空气中衰减较大,因此,选择合适的超声波传感器对于气固两相流参数检测至关重要.通过运用有限元软件COMSOL构建超声法测量气固两相流的仿真模型,研究接收装置接收信号的大小与气固两相流固相颗粒的粒径和发射频率的关系,为实际测量选取超声波传感器提供了理论依据和指导建议.     

精确的互相关算法在超声波流速测量中的应用

互相关算法能够比较准确地计算出声波在流速正反2个方向上的传播时间,进而得出时间差,并根据时间差求出流体的流速。但离散的互相关函数峰值的精度取决于采样间隔的大小,间隔减小精度会相应提高,但在实际的应用中计算量也会大幅度提高。在以单片机为核心的测量仪表中,这种规模的计算通常是不会被采用的,找到一种更简便的计算方法是解决问题的关键。在离散的互相关函数峰值附近,利用抛物线算法可以得出更精确的互相关函数峰值。这种方法允许采样间隔较大,计算时间可大幅度缩短,使同一测量精度的计算时间从3.7 s缩短到0.9 s左右。     

提高超声波流量计量精度的方法

时差法超声波流量计通过检测换能器发射和接收的超声波信号的传播时间信号,实现流量的计量。超声波换能器的谐振频率及超声波信号传播过程中相位和幅值的变化等因素,会影响对超声波信号到达时间的准确计量,从而影响流量测量的精度。准确计量超声波信号的到达时刻是提升时差法超生波流量计的计量精度的关键之一。针对换能器发射和接收超声波信号的处理和获取电路进行了设计和分析,得出了实验结果和实验数据,对实验结果给出了实验分析和结论,并通过软件算法给出了进一步提高测量精度的方法。     

Holdup characteristics of two-phase parallel microflows

Two-phase parallel microflows, i.e., stratified flow and core-annular flow, have many applications in lab-on-chip devices. These include transport and reaction processes, such as liquid–liquid extraction and phase transfer catalysis. The phase holdup (fraction of the microchannel volume occupied by a specified phase) is a key parameter of these flow systems. In this work, mathematical models based on fundamental principles are used to predict the phase holdup in stratified flow and core-annular flow. For stratified flow, a two-dimensional model of flow in a rectangular channel of arbitrary aspect ratio is considered. A simpler one-dimensional model of stratified flow between infinite parallel plates is also analyzed. In the case of core-annular flow, axisymmetry is assumed in the model. The results of the models agree well with published experimental results. The dependence of phase holdup on the flow-rate fraction (the primary operating variable which can be controlled experimentally) is studied in detail. The nature of this relationship varies with the ratio of fluid viscosities and the channel’s aspect ratio (in the case of stratified flow). In the literature, the holdup is sometimes erroneously assumed to be identical to the flow-rate fraction. It is shown that this is not possible in the case of core-annular flow, while in stratified flow it is true only for a unique critical flow-rate. This critical flow-rate is viscosity dependent. The aspect ratio of the channel is found to have a considerable influence on the holdup in stratified flow when the fluids have different viscosities. However, even in such cases, there exists a point of geometric invariance at which the holdup is independent of the aspect ratio. At this point, the simple one-dimensional model of stratified flow can predict the holdup with complete accuracy.     

一种新型网丝传感器优化设计

基于COMSOL仿真软件,对新型的网丝传感器进行了仿真研究,并针对原油高含水情况下油分相含率检测,优化设计网丝式传感器结构。根据油滴尺寸、网格细分以及重建图像等问题提出了分块多阈值算法。仿真实验表明,基于分块多阈值算法进行图像重建,明显改善图像质量,提高了油分相含量检测精度。     

Application of Weighted Data Fusion Method in Multi-Path Ultrasonic Flowmeter Measurement北大核心CSCD

In view ofthe problem that the measurement error caused by a transducer can not work normally in the measurement of the flow velocity of the multi-path ultrasonic flowmeter. On the basis of multi-sensor data fusion theory and its improvement, a data fusion calculation method suitable for multi-path ultrasonic flowmeter is proposed, meanwhile the improved optimal weighted data fusion method can adaptively calculate the optimal weight coefficient after each measurement. The experimental results show that the flow velocity calculated by this method and the Gauss-Jacobi integral method are basically consistent when the channels of the flowmeter can work normally, When single channel of the flowmeter can not work normally, this method can be used to obtain more stable flow velocity than the Gauss-Jacobi integral method, it can reduce the influence of measurement error to the calculation result. © 2017, The Editorial Office of Chinese Journal of Sensors and Actuators. All right reserved.     

超声波气体流量测量系统的实现

超声波气体流量计因为其具有许多优点,在工业上获得越来越广泛的应用。超声波气体流量测量需应用一种新的流量测量技术,因为超声气体流量计工作在噪声较强的场合,且信号微弱。超声波气体流量计信号不能用传统的方法检测,在此,数字平均技术及相关技术得到应用,数字平均技术可使信号得到加强,相关技术可使渡越时间测量更精确,流量测量精度可达±2%。     

加权数据融合方法在多声道超声波流量计测量中的应用

针对多声道超声波流量计在流体流速测量时由于单个或多个换能器不能正常工作而导致测量存在误差的问题。提出在多传感器数据融合理论的基础上对其进行改进,使其适用于多声道超声波流量计的数据融合计算,同时改进后的最优加权数据融合方法能够在每次测量后自适应的计算最优权重系数。通过实验表明当流量计各声道均能正常工作时,该方法与Gauss-Jacobi积分法计算得到的流速值基本一致,当流量计单个声道不能正常工作时,应用该方法可以得到比Gauss-Jacobi积分法更加稳定的流速值,能够减小测量误差对计算结果的影响。     

在线超声波流量监测系统设计及其应用

为解决地源热泵系统中的进出水流量测量,设计研究基于超声波时差法原理的非接触式在线流量监测装置。系统以STM32F407 ZE为主控制器,定时采集流量、完成数据封包、加密和远端服务器交互任务;以MSP430F2618为流量测量控制器,采用时差法以TDC-GP22精准测量超声波在介质中传播时间,实现管道流体流速、流量实时监测。系统测试结果实现流量数据测量及上传存储到远端服务器,满足地源热泵系统流量监测需求。