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International Society for Industrial Process Tomography

11th World Congress on Industrial Process Tomography

Recent advances in the improvement of the measurement accuracy of capacitance wire-mesh sensors

F. A. Dias1*, P. Wiedemann1, E. Schleicher1, M. J. da Silva2, U. Hampel1,3

1Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany

2Institute of Measurement Technology, Johannes Kepler University Linz, Linz, Austria

3Chair of Imaging Techniques in Energy and Process Engineering, Technische Universität Dresden, Germany

*Email: f.dias@hzdr.de


ABSTRACT

In this paper, we report recent advances in the improvement of the measurement accuracy of capacitance wire-mesh sensors. We review the principles of the wire-mesh sensor and discuss the problem of inherent energy losses. An advanced model that combines finite element analysis and an electronic circuit model capable of predicting such losses is also introduced. Then, we discuss different procedures and methods, which improve the measurement accuracy of capacitance wire-mesh sensors by suppressing or correcting loss effects. First, limitations of a threshold method are discussed, in particular, for water-oil-gas three-phase mixtures. Next, we discuss a procedure based on the optimization of the electronic circuit of the sensor to suppress losses and crosstalk. This improves the measurement accuracy, but only for fluids with narrow dynamic range in their electrical impedance. Finally, we discuss a method based on a modified wire-mesh sensor with extra transmitter electrode embedded in the dielectric construction material, which allows predicting nonlinear behaviors in sensor readings and compensating for them in later post-processing. In contrast to the threshold method and the optimization circuit procedure, the latter allows improved measurement accuracy, reducing local phase fraction deviations from more than 30% to less than 5% for a much wider impedance range.

Keywords: wire-mesh sensor, multiphase flow, impedance measurement, three-phase flow

Industrial Application: ‘General’

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