The Design And Application Of ECT System Based On Generalized Vector Sample Pattern Matching Method

Electrical capacitance tomography (shortened form ECT) technology is one of process tomography technology, which based on capacitive sensing mechanism, and obtained the information by the changes of dielectric properties in the physical field. It has achieved rapid development in recent years for the advantage of non-invasive, non-radiation, fast response and low cost. ECT has been widely used in gas-solid flow parameters detection and other fields.The 12-electrode electrical capacitance tomography system is the research content in this thesis. The main research is focus on the weak capacitance detection, multi-channel data acquisition and image reconstruction algorithms, and other key issues. On this basis, a set of measurement and data acquisition devices is designed and a new image reconstruction algorithm, the generalized vector sample pattern matching algorithm is proposed, the experiment of particle volume fraction monitoring in fluidized bed downer, which based on ECT system, is also completed.The thesis is focus on the application of air solid two-phase flow parameters detection in in circulating fluidized bed, the hardware design which based on the multi-channel data acquisition and control module Agilent 34980A and the Agilent E4980A precision LCR meter is presented, the software design is completed, which using the SCPI standard command set to drive VISA.COM control, have realized the intelligent control to Agilent series instrument.Several typical ECT image reconstruction algorithms and their characteristics are simply analysed, a image reconstruction algorithm called generalized vector sample pattern matching method is proposed, several flow pattern of air solid two-phase flow is reconstructed by Mathematica7.0 numerical simulation software, the images reconstructed by generalized vector sample pattern matching method are compared with linear back projection method and Landweber iteration method separately. Simulation results and analysis of image quality evaluation parameters show that the images reconstructed by generalized vector sample pattern matching method have high precision and good quality.Using the ECT system designed by this thesis, the expriment for detection of particle volume fraction in circulating fluidized bed downer is carried out. The particle volume fraction distribution of a cross-section in circulating fluidized bed downer during different air solid two-phase speed can visualize apparently. In addition, three evaluation parameters of the particle volume fraction error, residual capacitance and capacitance correlation are given, and make the corresponding analysis.