Capacitance sensor design for reducing errors in phase concentration measurements
Capacitance sensor design for reducing errors in phase concentration measurements
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DOI：
10.1016/s0955-5986(98)00006-5
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发表时间：
1998-03-01
影响因子：
2.2
通讯作者：
Hammer, EA
中科院分区：
文献类型：
--
作者：
Tollefsen, J;Hammer, EA
研究了一种电容传感器结构，该结构可以测量原油中的含水率和不溶气体，其精度高于现有的非侵入式电容传感器。在这种传感器中，表面电极是螺旋形的，使得电场从传感器的一端到另一端扭转180度或360度。该模型是基于“有限元法”（FEM）。该模型使我们能够模拟螺旋传感器的电容作为流动参数的变化的函数，包括水分数、空隙率、介电常数和流动分量的分布，以及传感器几何形状和设计的变化，例如传感器的长度、保护电极的类型、电极绝缘层（衬垫）的厚度和介电常数、传感器屏幕的直径，利用该数学模型对螺旋平板电容传感器的灵敏度、准确度和流型无关性进行了优化设计。我们的模拟表明，通过使用螺旋表面电极的整体精度估计为+/- 0.4%的气体/油混合物和+/- 5%的油连续的水/油混合物的满量程。(C)1998爱思唯尔科技有限公司版权所有。
A capacitance sensor configuration which can measure the water fraction and undissolved gas in crude oils with higher accuracy than currently available non-intrusive capacitance sensors has been studied. In this sensor the surface electrodes are helical so that the electrical field is twisted 180 degrees or 360 degrees from one end of the sensor to the other.This sensor has been investigated in detail by means of a three-dimensional capacitance model based on Poisson's equation. The model is based on the "Finite Element Method" (FEM). This model enabled us to simulate the capacitance of the helical sensors as a function of changes in flow parameters, including water fraction, void fraction, permittivity and distribution of the flow components and changes in sensor geometry and design such as length of the sensor, type of guard electrode, thickness and permittivity of the electrode insulation layer (liner), diameter of sensor screen, etc.The model was verified against measurements on different types of sensors and flow regimes, and the maximum difference between simulated and measured results was +/- 5%.The mathematical model was used to optimize the design of the helical surface plate capacitance sensor with respect to sensitivity, accuracy and flow regime independency. Our simulations show that by using helical surface electrodes the overall accuracy is estimated to be within +/- 0.4% for gas/oil mixtures and +/- 5% for oil-continuous water/oil mixtures of full scale. (C) 1998 Elsevier Science Ltd. All rights reserved.