On-line continuous measurement of particle size using electrostatic sensors

The development of a reliable, cost-effective instrument for on-line particle sizing remains a challenging area worldwide. This paper presents the design and evaluation of a new electrostatic sensor combined with a novel digital signal processing algorithm for the on-line continuous measurement of the mass median size of particles in a dilute-phase pneumatic suspension. Key design aspects of the constituent elements of the sensor, including a wire-mesh electrode, signal conditioning electronics and digital signal processing algorithm are described. Experimental results obtained using a typical range of particulate materials demonstrate that, under constant mass flow conditions, the processed output of the sensor is capable of indicating the mass median particle size with a relative error no greater than 15%. A critical appraisal of the technique, including advantages and limitations, is also included.