The Design And Research Of ECT Sensor Based On Multi-physics

In modern industry, multiphase flow is widely used in chemical engineering and energy, metallurgy and medicine and other production sectors of the national economy especially in the petroleum industry. The continual exploitation of onshore oil and gas resources make the land oil and gas resources short. However, the ocean space especially the South China Sea is rich in oil and natural gas resources which will grow into a comprehensive development model in the future. As to the exploitation of offshore oil and gas resources, the marine engineering equipment is the technical guarantee and among which the development of multiphase flow detection technology is inevitable during the underwater operation especially the deep water operation.As a kind of Process Tomography(PT) Technology, the capacitance value in the measured field is measured by sensor array which is placed outside of the measured object in Electrical Capacitance Tomography(ECT), the information of medium distribution on the measured field cross section is acquired, and the images of the distribution of each phase medium are reconstructed with related programs at last. ECT feasures non-intrusion and non-radiation, fast response and good safety with wide popularity and rapid development. It is with enormous development potential and broad application prospects in solving the measurement problem of multiphase flow.However, there is still a gap between current ECT and practical application, thus further research are required to promote its development and practicality.The study on design and optimization of the ECT sensor which is based on8-electrode regular geometry ECT sensor is carried out in the dissertation. And, the preliminary study on design and sensitive field analysis of irregular geometry ECT sensor are proposed. The main works of the dissertation are as follows:(1) The establishment of three-dimensional ECT simulation model and forward problem are studied. The mathematical expression of sensitivity field is obtained according to the electric field characteristics of ECT sensitivity field. The three-dimensional ECT simulation model is established with COMSOL simulation software based on multi-physics and the forward problem is solved in the real environment.(2) The physical simulation model of 8-electrode regular geometry three-dimensional ECT sensor is established in the study. The structure and parameter of electrode coverage, axial length and shielding layer settings are optimized. Then, the influence of these parameters on the ECT system is analyzed from the aspects of maximum capacitance value and the minimum capacitance value, the change range of empty tube/full tube capacitance and the electric field characteristic of sensitive field,and the optimized geometric parameters are obtained finally. The designed ECT sensor is proved to be optimized as the sensibility in the axial direction is distinguishable and the sensitive field is well-distributed analyzed by the COMSOL software.(3) The necessity of designing irregular geometry ECT sensor is proposed for application scenarios of irregular cross-sectional shape. The design and manufacture of irregular geometry ECT sensor are provided foundation by the Industry 4.0 mode. The exploratory study on measured object with irregular elliptical cross section is carried out with a designed irregular geometry ECT sensor composed of sensor electrode plates and shielding electrodes and an outer shield. The geometric parameters are selected of sensor electrode numbers and angle, axial length and the radius of outer shield, and the suggestion of installation style of irregular geometry ECT sensor is proposed at last. The preliminary study on the sensitive field of irregular geometry ECT sensor is made and the method of non-equalization meshing and sensitivity calculation are presented for the irregular geometry sensitive field.