Measurement of 2-D Temperature Distribution in a Biomass Silo Through Acoustic Tomography

Spontaneous heating and self-ignition of biomass fuels pose critical challenges in the regular operation of biomass power stations. The measurement of temperature distribution in stored biomass at power stations is essential for obtaining timely temperature information and hence minimizing fire risks. This article presents a methodology through acoustic tomography (AT) for measuring the temperature and temperature distribution of stored biomass in a silo. A measurement model is developed to obtain the time of flight in stored biomass based on cross correlation and thresholding methods. Image algorithms are utilized to visualize the temperature distribution. Wood pellets, as the primary fuel source for biomass power stations, are used as a test biomass fuel. Experimental results suggest that AT is able to measure the temperature distribution of wood pellets with an accuracy of ±6% over the range of 20°C~65°C. In addition, the relative error of the central location in the high-temperature region is within ±4%, while the relative error in measuring the area of the high-temperature region is within ±5%.