Axial solid's concentration in the riser of a circulating fluidized bed.

N. A.  Akhtar; X. S.  Wang; B. M.  Gibbs

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Axial solid's concentration in the riser of a circulating fluidized bed.

Author(s)

N. A. Akhtar Fuel & Energy Department, University of Leeds, Leeds, UK

X. S. Wang Fuel & Energy Department, University of Leeds, Leeds, UK

B. M. Gibbs Fuel & Energy Department, University of Leeds, Leeds, UK

Abstract

In this paper the ascendancy of physical parameters involving changes in solid's circulation rate, air staging. excess air and gas velocity were scrutinized on the axial solid's concentration in a circulating fluidized bed combustor (0.161 m ID and 6.2 m tall riser). Instantaneous pressures were ascertained at different locations along the riser by means of pressure transducer and were then transcribed wit computer data acquisition system. Silica sand classified in Geldart Group BV (particle diameter 125 mm and particle density of 2500 Kg/m3) was employed as the main circulating material in this study. Experimental results evinced that solid's concentration first dwindled with the height above the air distribution plate and then seemed to be steadfast. The height of the dense bed at lower section of the riser perceived contingent on the above parameters. Hydrodynamically fully developed region prevailed at ≥ 3.0 m height of the riser whereas at:≤2 m elevation persisted developing flow region. Carbon mass fraction sampled with newly designed nitrogen purged probe waned from 3.31% to 1.15% in the riser. Correlations developed for the appreciation of solid's circulation rate and superficial gas velocity in the riser are stipulated in this paper as well.

Publication Details

Page(s) 61-69

DOI DOI not available

Published Journal: Journal of Pakistan Institute of Chemical Engineers, Volume: 21-22, Issue: 1--2, Year: 1994

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