Research On Detective Principle And Methods Of ECT/ERT Dual-Modal System

With the development of information technology and the improvement of industrial automation level, the request for the real-time detection to multi-phase flow parameters is stricter, and there is more measurement need for the parameters of multi-phase flow. Electrical Tomography becomes a focus more and more, for its following characters: low-cost, good real-time performance, non-invasion, simple system structure, non-radiation and safety.Electrical Capacitance Tomography (ECT) only reconstruct the dielectric constant distribution of the measurement object, and Electrical Resistance Tomography (ERT) only reconstruct the conductivity distribution of the measurement object, but there are both dielectric constant distribution and conductivity distribution for active multi-phase flow. So it is of great significance that ECT and ERT are combined properly to construct a dual-modal system to measure the parameters of multi-phase flow.In this thesis, the main work is shown as follows:1. The parallel resistance capacitance model of measurement object is presented, and the circuits, including the C/V conversion circuit and R/V conversion circuit, are analyzed by circuit theory. The variation rules of the resistance and the capacitance are researched, the effect of the frequency variation on the measurement ranges of R and C is analyzed, then the measurement ranges of R and C for single frequency excitement and multi-frequency excitement are analyzed, so a complementary optimization method is presented for the parameter choice of detection circuit in dual-modal system.2. Three kinds of dual-modal electrode structure are presented, and a better electrode structure is obtained by analyzing the voltage distribution which uses the finite element analysis software ANSYS; the optimization indexes are defined, two kinds of micro-structure are built, experiments are finished according to orthogonal experiment method, the effect of every kind of parameters on the indexes is analyzed, and the optimization model dimension is obtained.3. The dual-modal system is designed by using the idea of modularization. In the system, the real and the imaginary are measured separately so that the precision of the system is improved. The PC software is accomplished, and many kinds of measurement can be chosen by controlling the I/O port.4. A few experiments have been done on the basic of the hardware and software design. When the water is continuous phase, the change of sensitive areas can be reflected in ECT and ERT system by using the real and imaginary information, which lay the foundation for the further research.Finally, some improvement suggestions are presented at the end of the thesis.