Research On A Velocity Measurement System Of Gas-solid Two-phase Flow Based On Electrostatic Method

Gas-solid two-phase flow is applied in a wide range of industrial fields. Onlinemeasurement of the critical parameters has great significance in the industrialprocesses. The velocity of solid particle is one of the most important parameters in themeasurement of gas-solid two-phase flow. However, gas-solid two-phase flow isdifficult to measure. A wide variety of factors influence the measurement in differentways. Electrostatic sensor has the advantages of simple structure and high sensitivityand it is supposed to be one of most promising methods.Based on the electrostatic sensor, an online measurement system, which is usedfor online measurement of solid velocity in gas-solid two-phase flow, is presented inthis paper. The main work of this paper is shown as followed:1. A charge amplifying circuit of electrostatic sensor was designed based on thecharge source model of electrostatic sensor. The operational amplifier OPA129UB isused to transform the charge into voltage. The voltage signal is filtered and amplifiedby the subsequent circuit. The amount of inductive charge on the electrostatic sensorcan be measured accurately by the circuit. The charge amplifying circuit has theadvantage of high anti jamming ability.2. An embedded correlator was designed using digital signal controllerdsPIC33FJ256GP710. The embedded correlator is designed to gather the electrostaticsignal, calculate the correlation velocity and communicate with the host computer.The online measurement system based on the electrostatic sensor consist of theelectrostatic sensor, the charge amplifying circuit and the embedded correlator.3. The experimental research of the online measurement system was conductedusing the belt electrostatic induction apparatus and the gas-solid two-phase flow rig totest its accuracy, immediacy, repeatability, reliability and anti jamming ability.4. The large-caliber multi-channel electrostatic sensor was used to measure thevelocity of pulverized coal in pneumatic pipeline at Huaneng YangliuqingCogeneration Power Plant. The electrostatic signal of every electrostatic sensor wasgathered to measure the velocity of pulverized coal in pneumatic pipeline.