Study On Measurement Principle Of Electrostatic Sensor Used In Dilute Phase Gas-solid Two-phase Flow

Gas-solid two-phase flow is applied in a wide range of industrial fields. On linemeasurement of the critical parameters and subsequent optimized control have greatsignificance to improve operation efficiency, reduce costs and conserve energy.However, gas-solid two-phase flow is difficult to measure. A wide variety of factorsinfluence the measurement in different ways. Electrostatic sensor has the advantagesof simple structure and high sensitivity and it is supposed to be one of most promisingmethods. In this paper the measurement principle of electrostatic sensor, which isused in dilute phase gas-solid two-phase flow, is analyzed. The main work of thispaper is shown as followed:Based on the frequency characteristics of electrostatic sensor and themeasurement error of the transit time, the principle of selecting sampling frequency isillustrated. After the sampling frequency is selected, taking the variance of transit timeand real application requirements into account, the principle of selecting integral timeis introduced.Using the belt electrostatic induction apparatus, the affects of solid particles’distribution and velocity profiles to the correlation velocity measurement areexplained.Based on the gas-solid two-phase flow rig, the change of correlation velocitywith different solid concentrations and superficial air velocities under dilute phasepneumatic conveying is examined.The electrostatic fluctuation signal is analyzed based on the time-frequencycharacteristics and multiscale entropy. Besides, the superposition of frequencycharacteristics of electrostatic sensor at different radial positions is studied.An embedded correlator is designed using digital signal controller dsPIC, and itsperformance is discussed using the belt electrostatic induction apparatus.