Electrostatic Coupled Capacitance Sensor for Gas Solid Flow Measurement

Both electrostatic and capacitance sensing techniques have been increasingly attractive for gas solid flow measurement. Although independent flow monitoring can be achieved by either an electrostatic sensor or a capacitance sensor, the fusion of them could provide diversified flow information with simplified sensor structure when used for gas solid flow measurement. In this paper, a novel electrostatic coupled capacitance sensor is proposed for gas solid flow measurement, which could simultaneously act as an electrostatic sensor and a capacitance sensor and thus acquires electrostatic and capacitance information within the same sensing space. Through an in-depth theoretical analysis of the sensor principle based on a pair of concave electrodes, a corresponding interface circuit is designed for signal conversion and extraction. Experiments carried out on a single particle test rig and a belt-pulley rig verify that the electrostatic and capacitance signals can be simultaneously obtained from the proposed sensor through the designed interface circuit. Furthermore, a sensor prototype with a three-electrode configuration is designed to measure the particle velocity, concentration, mass flow rate and charge level on a gravity-fed solids flow rig, demonstrating the potential application of the developed electrostatic coupled capacitance sensor for the gas solid flow measurement.