Structural Design Of 3D ECT Sensor And Optimization Of Image Reconstruction Algorithm

Electrical Capacitance Tomography(ECT)is one of the effective methods for two-phase flow parameter measurement.By uniformly arranging the electrode array in a certain arrangement on the outer wall of the pipeline equipment,measuring the capacitance value between the pair of electrodes,and then According to the different dielectric constant distribution inside the measured object,the image reconstruction algorithm is used to reproduce the information such as the shape of the measured object.Because of its low cost,non-invasive,easy to implement,non-hazardous,simple structure and so on,electrical capacitance tomography has important significance and wide application in the fields of petroleum,chemical production and power transmission.In this paper,three-dimensional ECT system is researched on sensor structure design and image reconstruction algorithm.The main work is as follows:The finite element analysis method is used to establish a multi-layer direct three-dimensional capacitive tomography sensor model.The physical field of the sensor model is simulated using MATLAB.The electrostatic field settings,material selection,and structural parameters were analyzed experimentally.Aiming at the influence of the sensor structural parameters on the performance of the capacitance tomography system,by changing the structural parameters such as the plate opening angle,the tube wall thickness,the rotation angle of the plate,and the space between the shield and the plate,the empty tube is full The dynamic range of the capacitance value and the perception of the sensitivity of the capacitance change are analyzed and compared,and the curve of the capacitance value as a function of the structural parameter is plotted to determine the optimal sensor structural parameter.Aiming at the multi-layer ECT sensor structure model,based on three-dimensional simulation,based on the electrode excitation modes of traditional single-electrode excitation single-electrode measurement,two new electrode excitation modes of two-electrode excitation two-electrode measurement are proposed,and the capacitance under different excitation modes is compared The size and variation of the measured value,the difference in sensitivity uniformity,and the quality of the image reconstruction.The experimental results show that the sensitivity uniformity of the sensitive area is better,the capacitance measurement is larger and the dynamic range is smaller in the combined excitation mode,and the quality of the reconstructed image is better.Due to the highly nonlinear problem,there is a mismatch between the position and size of the measured object.To solve this problem,the greedy and sparse method is used to reconstruct the 3D image.The K-SVD dictionary learning method is used to construct a redundant sensitivity matrix using nonlinear simulation.The redundant sensitivity matrix data is trained to better capture the measured object Typical structure.It can be seen from the simulation experiment results that this method can effectively improve the reconstructed image quality.