Electrostatic monitoring of coal velocity and mass flowrate at a power plant

Abstract

ABSTRACTIt is necessary to monitor and balance the pulverized coal velocity and flowrate among the conveying pipelines leading to injection burners and to optimize the air-coal ratio for safety, economical operation, and reduction of pollution of coal-fired boilers in power plants. A novel electrostatic sensing system is reported for monitoring the velocity and relative mass flowrate of pulverized coal. The design, implementation, and on-plant trials of the system are reported. The velocity of pulverized coal was determined by autocorrelating the output derived from a linear electrostatic sensor array. The relative concentration and mass flowrate were obtained by the root mean square values of the output of two ring-shaped electrodes with the consideration of the pulverized coal velocity. The instrumentation was evaluated on a full-scale 600 MW power generation unit. The results demonstrate that the technique provides reliable measurement of pulverized coal velocity, relative flowrate, and split distribution among the injection pipes from the same pulverizing mill. The prototype achieved split balance and optimized air/coal ratio in combination with the pulverized coal balancing control valve and proportional-integral-derivative controller in fuel injection pipes in a power plant.