Online particle size measurement through acoustic emission detection and signal analysis

Accurate determination of particle size distribution is critical to achieving optimal combustion efficiency and minimum pollutant emissions in both biomass and coal fired power plants. This paper presents an instrumentation system for online continuous measurement of particle size distribution based on acoustic emission (AE) method. Impulsive AE signals arising from impacts of particles with a metallic waveguide protruding into the flow carry information about the particle size. The relationship between the particle size and the peak AE voltage has been established through physical modeling of particle impact. A particle sizing algorithm is developed using peak detection techniques. Experimental results obtained with glass beads demonstrate the capability of the system to discriminate particles of different sizes from the recorded AE signals. The system has several appealing features such as online measurement, high sensitivity, simple structure, minimum invasiveness and low cost, which make it well suited for industrial applications.