Study On Image Reconstruction Algorithms Of Electrical Capacitance Tomography

Multiphase flow is widely applied in industry field, multiphase flow measurementplays a more and more important role in many areas of industry and scientificresearch. Accurate measurement of multiphase flow can open out the mechanism ofmultiphase flow, set up model of multiphase flow, and also provide essential basesfor forecast, design and optimized control of flow process. Process Tomography (PT)technique, which has been developed rapidly in recent ten years, has greatdevelopmental potential and wide industrial application prospect. Having manydistinct advantages such as low cost, wide application field, simple structure,non-invasive measurement and better safety, Electrical Capacitance Tomography(ECT) has being the most popular research direction and the main development inprocess tomography technique. There is still a lot of work to be done before practicaluse of the technique. The object of this dissertation is on the research of 8-electrode ElectricalCapacitance Tomography system. The main topic studied is image reconstruction,flow pattern identification. The main works are as follows: 1. While analyzing the present flow imaging technique, this paper analyzes and sums up the features of multiphase flow, sort and parameter. It also analyzes the present status and the history of multiphase flow measurement. It points out the important meaning of multiphase flow measurement to the science and industry production, and sums up the research direction and developing trend of the future multiphase flow measurement. 2. Through the brief introduction of the basic principles of process tomography, the system constitution, the basic features and developing status, the paper introduces the process tomography based on various sensing technique. 3. The paper introduces the constitution of electrical capacitance tomography, analyzes the principle and proposes the mathematical model of sensitivity field, discusses the peculiar advantages and research status of the technique.Several image reconstruction algorithms on electrical capacitance techniqueare compared and analyzed. Based on the concept of double integral, thispaper sets up a mathematical model of image reconstruction which is brief andreliable on theory.To obtain the high quality image of discrete phase distribution, it takes the useof the ART algorithm based on the landweber iteration method, and improvethe ART algorithm. The experimental results show that the model is reliable,the accuracy of algorithm is higher, the reconstructed image accords with theactual situation, and the quality of reconstructed image is improved.Maximum Entropy image reconstruction algorithm is put forward. Theexperimental results show the image reconstruction model is reliable. Theaccuracy of the algorithm meets the expected requirement of flow patternidentification.