The Research Of Electrical Capacitance Tomography System Applied In Measurement Of Two-phase Flow

Electrical capacitance tomography (ECT) is a new technique developed rapidly in recent years. It is a novel approach for two-phase flow parameters measurement, and has great developing potential in industrial application. But currently there is still a lot of work to be done before practical use of the technique. The main problems are the measurement of low value capacitance, image-reconstruction and so on. This thesis based on this field's current research status and practical application needs, designs a ECT system's hardware structure based on upper and lower computers which are cooperating, demonstrates the AC-based measurement circuit which has been currently used and designs the corresponding signal transform circuit. This transform circuit becomes the output signal to DC signal which is easy treatment and is transmitted to Lower computer to treat. Theoretical analysis indicates this hardware system has very high precision for measurement. Through analyzing various currently used image-reconstruction algorithms, an amendatory image-reconstruction algorithm based on iterative algorithm which is a high-quality image-reconstruction algorithm is presented. This amendatory algorithm's feasibility is theoretically demonstrated. The simulation results show that the image-reconstruction quality and precision of this amendatory algorithm have no obvious difference compared with the primary iterative algorithm, but the image-reconstruction's speed is obviously faster so that can satisfy the request of real time flow pattern identification.On the basis of previous research, this thesis respectively designs the upper and lower computers' software system based on modularize design method. The whole software system lets the couple computers divide up the work and cooperate. The upper computer controls the lower to conduct data acquisition, and conducts image-reconstruction work after receiving the data from the lower. The whole ECT system designed in this thesis can be applied in practical measurement.