(159b) Solids Fractions and Flow Characteristics in a Cfb as Measured with a Fiber Optic Probe

Authors: 
Seachman, S. M., National Energy Technology Center, US DOE
Yue, P. C., National Energy Technology Center, US DOE
Taylor, E., National Energy Technology Center, US DOE


A multi-fiber optical reflection probe was used to measure particle velocities and solids loading in the riser of a 0.3 m circulating fluidized bed (CFB). An equation to calculate the localized solids fraction was developed based on the Beer-Lambert Law. The probe was inserted at radial positions, varying heights, and azimuthal locations. These solid fractions were compared with those estimated from pressure drop measurements and literature. The values followed the trend of the pressure measurements and previous calculations. In addition, the measurements found with the probe also illustrated that the solids concentration in the riser was more dilute in the center of the riser and became dense as it approached the wall. While the particle velocities were symmetric around the riser their fluctuations were not as shown with the azimuthal measurements. These fluctuations were characterized using the turbulent kinetic energy. Solids concentration in the fully developed region of the riser was relatively symmetric. In addition, the concentration and distribution did not change after entering the fully developed region. Because the fiber optic probe only picks up a portion of the reflected light, further calibration of the probe will be needed to obtain exact values of the solids concentration.

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