Fringe effect of electrical capacitance and resistance tomography sensors

Abstract

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Switch Configuration Effect on Stray Capacitance in Electrical Capacitance Volume Tomography Hardware

“…Stray capacitance is parasitic signal from other sources and affected by some factors such as screen enclosure, cable connecting sensor with data acquisition system, and switch used for selecting electrode pair [8]. Usage of axial and radial guard in the sensor design would reduce the fringe effect and stray capacitance, which occur from the rear of electrode pair [9]. Coaxial cable is one of sources of stray capacitance that is high enough, about 100 pF per meter length.…”

A dual-modality electrical tomography sensor for measurement of gas–oil–water stratified flows

“…ERT with voltage-excitation has been discussed in details by Sun and Yang [17]. The prevalence of current-injection in ERT for medical applications is due to two reasons: the first one is the consideration of safety for human body by controlling the injected current, which is no longer the case in most industrial applications; the second one is the influence of contact impedance between the electrodes and human skin or electrolyte on the resistance measurement, which is more significant in the case of voltage excitation for medical applications.…”

“…However, there is no evidence that this system can be applied in the situations with conductive background medium since the background medium was always set to be non-conductive in their experiment. Another alternative solution is to employ a dual-modality system based on an ECT sensor with electrodes mounted on the inner surface of a pipe, denoted as interior electrodes, for both ECT and ERT measurements, as suggested by Sun and Yang [17]. Up to now, however, almost no experimental result has been reported on the application of this kind of dual-modality sensors for measuring complex multiphase flows, e.g.…”

“…With an integrated dual-modality sensor mentioned above, the ERT measurements need to be taken by using the voltage-excitation and current-measurement strategy, as suggested by Sun and Yang [17], instead of the conventional current-injection and voltage-measurement strategy [5,14,2,13,3]. This means that the same excitation strategy is used for both ECT and ERT measurements.…”

Applications of tomography in the oil-gas industry – Part 2

“…Spatial and/or temporal resolutions inherent with different physical measurement principles can pose limitations to measuring fast varying multiphase flows (sometimes limited by the accuracy and speed in the image reconstruction); further development is continuing (Wang, Hu, Wang, & Wang, 2012;Kim, Khambampati, Kim, & Kim, 2013;Liu, Lei, Wang, & Liu, 2013;Liu, Yang, He, & Tan, 2013;Sun & Yang, 2013). Cost, robustness and reliability are also issues to be addressed in transferring technology to industrial applications.…”