Study On The Capactively Coupled Electrical Resistance Tomography System Based On Phase Sensitive Demodulation Method

Being one of the most important process tomography technologies, electrical resistance tomography (ERT) technique has greatly progressed in industry. It has the advantages of visualization, high speed, low cost, no radiation hazard, and non-intrusive, etc. However, for the traditional ERT systems, the contact between the electrodes and liquid may result in electrode corrosion and will decrease the mechanical strength of the sensor pipe, which limits the application of ERT in industry.To solve the problem, the contactless electrical resistance tomography technique was proposed and a system prototype was successfully developed. The conductivity distribution of the liquid between electrodes can be measured without direct contact with the liquid.The main works of this dissertation are listed as follows:(1) Based on the capacitively coupled contactless conductivity detection (C4D) principle and ERT technique, a new capacitively coupled ERT (CCERT) technique which is used to measure the conductivity distribution of the liquid contactlessly was proposed. Compared with the traditional ERT systems, the electrodes of the sensor in this method do not need to be in contact with the measured liquid. This completely avoids the electrode corrosion and expands the application of ERT.(2) Considering the special requirement of the data acquisition system of the new CCERT technique, based on the phase sensitive demodulation (PSD) method, a new method which achieves the data acquisition was proposed.(3) A novel CCERT prototype system which is based on the PSD method was developed. The real-time images of the conductivity distribution were successfully acquired. Experiment results show that the system has satisfying real-time performance.