Defluidization Detection of Sand and Sawdust Mixtures by Using the Gaussian Spectral Pressure Distribution Technique

Abstract

Gas-solid fluidization systems are widely used in industrial processes, such as in the combustion and gasification of fuels for power generation. In these systems, the defluidization phenomenon originated by agglomeration of particles can lead to problems for a stable operation or appropriated conversion efficiency. This work carries out an experimental study aiming to determine the defluidization region of binary mixtures composed by inert material and biomass particles. The experiments were performed in a bench-scale bubbling fluidization system with sawdust to total bed inventory ratio fixed at 0, 2.5 and 5.0% in weight. The experimental equipment was instrumented with fast response pressure transmitters connected to a data acquisition system. During tests a sampling frequency of 400 Hz and 2,048 data points for sample were adopted. The signal pressure of the bed was processed by using the LabView TM 10.0 software. The measurements showed that the extension of defluidization region increase with higher sawdust to bed inventory ratio and when the mean diameter of inert particle also increases. Results confirmed the Gaussian spectral pressure distribution technique is very efficient for detecting the defluidization region in all cases analyzed, suggesting it as useful tool for controlling fluidized bed processes.
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