Heat transfer to horizontal tubes in the freedboard region of a gas fluidized bed

Authors

  • S. E. George,

    1. Department of Chemical Engineering and Coal Research Centre, University of British Columbia, Vancouver, Canada V6T 1W5
    Current affiliation:
    1. Shell Canada Research Center, Oakville, Canada L6J 5C7
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    • The experimental work described in this paper was carried out at McGill University, Montreal, Canada.

  • J. R. Grace

    1. Department of Chemical Engineering and Coal Research Centre, University of British Columbia, Vancouver, Canada V6T 1W5
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Abstract

Overall heat transfer coefficients were measured for an instrumented horizontal tube of diameter 25 mm in the feedboard region above fluidized beds of 102 μm, 470 μm and 890 μm sand in a 0.25 m × 0.43 m × 3.0 m tall pilot scale column. The superficial air velocity varied from near minimum fluidization to 1.7 m/s. The instrumented tube was placed at different positions in a 16-tube bundle. The measured heat transfer coefficients were bounded for tubes near the expanded bed surface by the immersed tube values, and for remote tubes by the values for particle-free air in crossflow. The results are correlated within ± 12% by a simple equation which incorporates these limits. The results are in good qualitative and quantitative agreement with previous experimental results.

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