Research On Optimizing Output Characteristics Of Electrical Capacitance Tomography Sensor And Its System Design

Electrical Capacitance Tomography(ECT)is a visual multiphase flow parameter detection technology.Because of its advantages such as non-invasiveness,high time resolution,no radiation,wide application range,and low cost.It has received extensive attention and research in related application fields involving gas-solid two-phase flow,gas-liquid two-phase flow and three-phase flow.The ECT sensor itself has problems such as low sensitivity,uneven spatial distribution,and large output signal dynamic range,which not only affect the quality of image reconstruction,but also place high requirements on the data acquisition system.The ECT data acquisition circuit takes into account high sensitivity,high resolution,and high signal-to-noise ratio,while also being able to adapt to a large input dynamic range.This has resulted in the ECT data acquisition circuit being a key and difficult point in system development.Therefore,optimizing the output characteristics of the ECT sensor is of great significance for improving the quality of image reconstruction and reducing the difficulty of data acquisition system design.Aiming at the shortcomings of traditional ECT sensors such as large output dynamic range and low sensitivity,this paper proposes an ECT sensor output characteristic optimization scheme based on isolated electrode technology,which can effectively reduce the output dynamic range of the ECT sensor and improve the overall sensitivity.The isolated electrode technology is introduced into the combined electrode ECT sensor to further reduce the output dynamic range of the sensor and improve the imaging quality at the same time.The dynamic range of the asymmetric isolated electrode combination ECT sensor proposed in this paper can be as low as 5.82,and the relative sensitivity can be as high as 2.91.A set of ECT data acquisition circuit has been developed.This set of weak capacitance signal acquisition circuit has high sensitivity,data acquisition speed,and high resolution.The measurement sensitivity is 64mV/fF,the data acquisition velocity can reach 793 frames/s,and the resolution is up to 4.8aF.A static experimental platform for gas-solid two-phase flow was built to verify the optimized results of sensor output characteristics and the data acquisition circuit developed.The experimental results show that the results of this article on the optimization of the output characteristics of the ECT sensor are in line with theoretical expectations,and the performance of the ECT data acquisition circuit designed and manufactured meets the requirements of use.The ECT sensor output characteristic optimization scheme proposed in this paper provides a new idea for the improvement of ECT sensor,which is helpful to push ECT technology to practical use.The developed ECT data acquisition circuit is relatively reliable and can be put into practical application with related software,which also laid the foundation for the follow-up research of the research group.