Investigation On Simulation And Electrostatic Measurement Method Of Gas-solid Two-phase Flow

Gas-solid two-phase flow is applied in a wide range of industrial fields.Measurement of the critical parameters has great significance in the industrialprocesses. However, as considerable factors can affect the result in varying degrees,gas-solid two-phase flow is difficult to measure. Electrostatic sensor has theadvantages of simple structure and high sensitivity and it is supposed to be one ofmost promising methods. In recent years, computer’s speed and capability isdeveloping rapidly, which makes it possible to investigate two-phase flow utilizingthe computational fluid dynamics (CFD) method.Based on the electrostatic sensor, combined with CFD simulation, this essaypresents the principle, function and improvement direction of the measure method.Main work of this paper is shown as followed:1. Analyze the principle of electrification mechanism of the particles in the flow,based on which, a charge amplifying circuit of electrostatic sensor was designed. Theoperational amplifier OPA129is used to transform the charge into voltage. Together,subsequent filtering and amplifying circuit is designed as required. The amount ofinductive charge on the electrostatic sensor can be expressed accurately by the circuitwith high anti-interference performance.2. Dilute gas-solid two-phase simulation model is built by computational fluiddynamics (CFD) commercial software. Aimed at disposing the unrealisticparticle-wall collision process model provided by the software, this essay makes animprovement of this model and build a more practical collision model. Correspondingsimulation is done with this model. Comparing the simulation results withexperimental data, the validity of the model is proved. Some flow characteristics hasbeen explored by this model.3. Rating test of the electrostatic measurement system is conducted on the beltelectrostatic induction apparatus. Experiment has been done on the gas-solidtwo-phase flow rig in Tianjin University, together with CFD simulation, to verify thereasonableness of the system designed.4. An industrial electrostatic sensor is designed and installed on the pneumaticpipeline at Huaneng Yangliuqing Cogeneration Power Plant. By collecting theelectrostatic signals on each electrode, velocity and concentration of the coal power in the pipe has been gained. Besides, performance test has been done.