A Comparative Study on the Influence of Particle Size on the Turbulence Characteristics within Gas-Solids Pneumatic Flows Using an Electrostatic Sensor and CFD-DEM Coupled Simulation

Electrostatic meters measure the charges carried by particles by detecting the induced charge or voltage on the electrode. In industrial environments electrostatic sensors are susceptible to low frequency noises; dynamic measurement is usually used, measuring the fluctuation of the charge or voltage induced on the electrode. The fluctuation of signal has been used to indicate the mean flow rate, the fundamental assumption that dynamic electrostatic meters are based on. However, due to the high conveying velocity in dilute gas-solids flows, particle degradation occurs from recursive particle-particle and particle-wall collisions. This has two significant effects. Firstly, this results in particle size reduction along with the conveying process. The total number and surface area of particles continuously increase for a given amount of material mass. Secondly, as total surface area increases and particle size becomes smaller, the surface tension overwhelms the gravitational force, the solid phase follows gas-phase more smoothly, and the turbulence level of particles reduces. The above two phenomena have opposite effects on an electrostatic dynamic meter. This paper presents simulation and experimental results which confirm each other regarding particle degradation and resultant turbulence level change.