Electrical capacitance tomography system for in-situ measurement

Abstract

The invention discloses an electrical capacitance tomography system for in-situ measurement. The electrical capacitance tomography system comprises a measurement pipeline, a flexible circuit board anda plurality of capacitance plates, and the plurality of capacitance plates are circumferentially distributed on the pipe wall of the measurement pipeline; the flexible circuit board is installed on the pipe wall of the measurement pipeline and is close to the capacitor plates, and the capacitor plates are connected with the flexible circuit board through lead electrodes. The electrical capacitance tomography system has the advantages of the stray capacitance reduction, the small size, the high test precision, the high spatial resolution and the like.

Description

technical field [0001] The invention mainly relates to the technical field of sensors, in particular to an electrical capacitance tomography system for in-situ measurement. Background technique [0002] Electric capacitance tomography (abbreviated as ECT) belongs to the local characteristic parameter testing technology, based on the difference in the dielectric constant of each phase material in multiple fluids, it can reflect the distribution and changes of each phase fluid in the measured medium 5 in real time, and has no radiation, It can adapt to the characteristics of opaque pipe walls and fluids, and the imaging speed is fast. In the past 20 years, ECT technology has been developed rapidly, and has been applied to the study of multiphase flow characteristics by many researchers, and a lot of fruitful work has been carried out. [0003] In 1988, the University of Manchester successfully developed an 8-electrode electrical capacitance tomography system. Since then, ECT t...

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Problems solved by technology

[0008] 1. Since all the sensors and data test collection systems of the ECT system are currently separated, the two are connected by cables, and the distributed capacitance introduced by the cables can reach more than 100pF, while the capacitance value between the plates of the ECT system is usually It varies from fF to several pF, so it is easy to cause the error of the measurement result to be too large. Although some compensation and filtering can be used to reduce the influence of stray capacitance, the effect is limited;

[0009] 2. Due to the existence of stray capacitance and the difference of each C / V conversion module, it needs to be re-calibrated before each test; if the movement of the cable will also cause the change of the distributed capacitance, so the sensor needs to be re-calibrated before each measurement. Carry out empty field and full field calibration, not suitable for long-term on-line monitoring of industrial sites;

[0010] 3. Each electrode needs to be connected to the test board through a coaxial cable 12. There are many and long cables, large volume, high cost, and low reliability. As a result, most of the current capacitance tomography systems are in the stage of laboratory samples. Difficult to apply to actual industrial sites; data acquisition systems all use boards and chassis, which are bulky and low in reliability, making it difficult to apply in industrial sites with harsh environments;

[0011] 4. In theory, the larger the number of capacitor plates 4, the higher the spatial resolution of the system, but the smaller the capacitance of a single capacitor, it is limited by the measurement accuracy of the current system (using more cables will affect the measurement accuracy). Currently, ECT The number of capacitive plates 4 in the system is less than 16, and the spatial resolution is not higher than 5%; the number of capacitive plates 4 is limited, and the spatial resolution is not high

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