Cross-correlation focus method with an electrostatic sensor array for local particle velocity measurement in dilute gas–solid two-phase flow

Abstract

The gas-solid two-phase flow has been widely applied in the power, chemical and metallurgical industries. It is of great significance in the research of gas-solid two-phase flow to measure particle velocity at different locations in the pipeline. Thus, an electrostatic sensor array comprising eight arc-shaped electrodes was designed. The relationship between the crosscorrelation (CC) velocity and the distribution of particle velocity, charge density and electrode spatial sensitivity was analysed. Then the CC sensitivity and its calculation method were proposed. According to the distribution of CC sensitivity, it was found that, between different electrode pairs, it had different focus areas. The CC focus method was proposed for particle velocity measurement at different locations and validated by a belt-style electrostatic induction experiment facility. Finally, the particle velocities at different locations with different flow conditions were measured to research the particle velocity distribution in a dilute horizontal pneumatic conveying pipeline.

Particle Velocity Measurement of Pulverized Coal flow on a Power Plant Using Electrostatic Sensor Array

“…The spatial sensitivity of an electrostatic electrode is defined as the absolute value of the induced charge on the electrode when a unit point charge is positioned in the sensing zone of the sensor [15]. The spatial sensitivity s can be determined as…”

“…However, the reconstruction methods typically faced ill-posed problem and their solutions were unstable and inaccurate [14]. The crosscorrelation focus method makes full use of ipsilateral, adjacent and contralateral electrode pairs, which could get information about particle velocity in more regions than that only in near-electrode region [15]. The experiment was conducted on a coal-fired power plant.…”

A Comparative Study of the Preamplifiers in Electrostatic Sensors Through Analytical Modeling and Experimental Evaluation

“…However, the repeatability of this method is low, as the amount of charge on the particle is uncertain. For investigation of the frequency response, a continuously fluctuating electric field can be generated using a power transmission belt [11,12,29] or pneumatically conveyed particle flow [10,20,21,28,29]. But the fluctuation of the electric field is stochastic in nature and the experiments cannot be repeated at all.…”

A comparative study of induced and transferred charges for mass flow rate measurement of pneumatically conveyed particles

“…1 shows typical types of electrodes with different geometrical shapes. An isolated electrode with a ring [9,12] or arc [11,13] shape is mounted outside of a dielectric pipe section that separates it from the particle flow and protected by an outer metal shield from external electromagnetic interference. The charge on the electrode originates purely from electrostatic induction of the charged particles.…”

“…The particle flow which is chaotic in nature leads to changes of spatial charge density in the vicinity of the electrode and hence the variation of the induced charge. The rate of variation of the induced charge, which is essentially an alternating current (AC) signal, is converted into a voltage signal using a transresistance amplifier (i.e., current-to-voltage converter) [9,[11][12][13]]. An exposed electrode can be either non-intrusive in the form of a ring [7,9,[14][15][16] or arc [8,17], or intrusive in the form of a rod [18,19] or ball [20][21][22]].…”