Capacitance Tomography Simulation And Experimental Verification On Two Phase Flow Of Water And Air

ECT is a soft field tomography, produced in the 80s of the 20th century, originated in medical CT imaging, with features of non-invasive, non-contact, high speed, safe, reliable and low cost, etc. It can be used in the areas of chemical, petroleum and power industry with the purposes of online monitoring, energy savings, increasing productivity and ensuring safety. Moreover, its security features make it harmless to human body, so for medical monitoring of clinical images it also has very good prospects.Capacitance tomography reasearches on two-phase and multiphase flow, which is divided into positive and inverse problems. Positive problem is the use of weak inter-electrode capacitance sensor detection to obtain capacitance sensitivity field; inverse problem is the use of measuring capacitance and the capacitance sensitivity field to calculate the distribution of dielectric constant, which gets the image of material distribution. Currently the main research focus is the design of sensors, low capacitance detection, data acquisition and fast and high precision, high-quality image reconstruction algorithm.This paper reasearches on two-phase flow. Sensitive map can be accessed by two methods of simulation and measurement. Currently, simulation is much easier than measurement. For the analysis of the relationship between sensitive field and the dielectric constant disturbance, two-dimensional ECT model with the length of radial plate ignored is established,then the simple electromagnetic method is used to obtain the sensitivity map. After that, modeling by the finite element method, simulation result can be got while radial length is considered, then both of them are compared to find the plate edge effect. The main subject of the inverse problem is the image reconstruction algorithm. The capacitor and the capacitance sensitivity field are got by finite element simulation, using LBP algorithm for fast image reconstruction as a basis, then a modified Landweber iteration, Tikhonov iterative image reconstruction algorithms, can give a good image. For the detection of water/air flow, the structural of the sensor is simulated and sensor is designed. Then, designing of the capacitive detection, peak detection and signal acquisition circuits, using these circuits to measure the actual capacitance sensitivity field of the water/air, and then using the measured capacitance data in the image reconstruction.