Particle size estimation of pulverized fuel in pneumatic pipelines using electrostatic sensing techniques

Particle size measurement of pulverized fuel (PF) provides useful data for efficiency improvement of a pulverizing system, optimization of fuel combustion and emission reduction on a fired power plant. This paper presents an experimental study of particle size estimation of pneumatically conveyed PF through electrostatic sensing. An electrostatic sensor head consisting of two narrow and one wide ring-shaped electrodes is designed and implemented to measure the PF velocity and quantify the features of the sensor signals. Experimental tests using particles with three different size ranges were conducted on the vertical pipe section of a 74 mm bore gas-solid two-phase flow test facility under various flow conditions. Test results show that the root-mean-square magnitude and power spectral density of electrostatic signals vary with particle size. For the same air velocity, the small change in particle velocity is an indication of particle size as the particle velocity decreases when the particle size is larger. The proposed method is capable of estimating PF particle size and has the potential to offer considerable advantages over its counterparts in power plant applications.