Design And Development Of Gas-Solid Two-Phase Flow Velocity Measurement System Based On Electrostatic

The parameters of gas-solid two-phase flow include the speed, concentration, mass flow and so on. The flow rate of solid particles which reflects the flow conditions of gas-solid flow is an important parameter. Detection of gas-solid flow rate for two-phase flow is important for industrial safety, economic and efficient operation.At present, using electrostatic sensing technology to measure the velocity of solid particles is a new technology field for international multi-phase flow test. However, the electrostatic sensing technique still has many problems and difficulties in theory and practice because of the complexity and randomness of gas-solid two-phase flow. In this paper, electrostatic sensing principles are analyzed theoretically aimed at the characteristics of electrostatic sensor, also electrostatic fluctuations of two-phase flow at different speeds are analyzed at different scales. The signal detection circuit and electrostatic collection system are also introduced in the paper, realizing real-time measurement of solid particle velocity.The main works are as follows:(1)Firstly, The electrostatic sensing principle has been derived, the working mechanism and electrostatic properties of the sensor’s spatial filtering has been analyzed; then it has been discussed about the influences of the electrostatic sensor plate width on the sensor sensitivity and sensitive field uniformity;(2) Secondly, multi-scale simulation experiments have been done to analyze the electrostatic fluctuations signals from the sensor with FFT and HHT; and the relationships of the signal time-frequency-energy have been drawn according to the analysis of the non-linear, non-stationary nature of the static signal;(3) Thirdly, a sensing circuit of eletrodynamic sensor was designed. Experimental results from the simulation show that the circuit can relize the measurement of electrostatic signal without distortion;(4) Fourthly, the cross-correlation velocity measurement algorithm based on electrostatic sensors are investigated. A measurement algorithm based on the amplitude-frequency characteristics of the signal is also introduced. The availability of spatial filtering algorithm in the field of fiber optic sensor technology is also verified in this part;(5) Fifthly, the system design is completed; the software for the ARM7platform based on the ADS environment is also done. The real-time measurement of gas-solid velocity can be realized by HMI. Furthemore, CAN bus interface is also provided, which is programmed by C#;(6) At last the experiment platform is set up, testing the system equipment and analyzing the experiment results and correcting the system error. The experiments include the correlation test of output signal, determination of sample rate and sample number and test of the precision and long-term stability of the system.