Mass flow rate measurement of pneumatically conveyed particles through acoustic emission detection and electrostatic sensing

Accurate online mass flow rate measurement of pneumatically conveyed particles is desirable to convert a conventional pulverized fuel fired power station into a smart thermal power plant. This paper presents a novel method for the online measurement of the mass flow rate of pulverized fuel through acoustic emission (AE) detection and electrostatic sensing. An integrated sensing head with an AE probe and three arc-shaped three-electrode electrostatic sensor arrays is developed. The proposed method determines the particle velocity by multiple-channel cross correlation of the sensor signals and extracts the information about mass flow rate from the AE signal arising from impacts of particles with a waveguide protruding into the flow. A theoretical model that relates the energy of the AE signals, the particle velocity and the mass flow rate is established. The sensing head was mounted on a vertical section of a 72-mm bore laboratory-scale test rig conveying fine silica particles. Experimental tests were conducted under a range of flow conditions to assess the performance of the developed measurement system. The results demonstrate that the instrumentation system is capable of measuring the mass flow rate of particles with a relative error within ±6.5% over the mass flow rate from 7 kg/h to 25 kg/h.