Hydrodynamics in the transport zone of a large-scale circulating fluidized bed boiler

Abstract

To investigate the hydrodynamics in large-scale CFB boilers, the pressure drops in the transport zone of a 550-MWe CFB boiler were measured by conducting five field tests. The circulating rates G s were calculated based on the pressure drop in the transport zone and then compared with the estimations via the correlations of the elutriation constant in single-particle elutriation theory and those of the saturation-carrying capacity in fast fluidization theory. The Colakyan & Levenspiel correlation of elutriation constant exhibited a good agreement with the experiments within ±14.02% error range. It's reasonable to use it for calculating G s in large-scale CFB boilers because of its wide experimental conditions. The flow regime remained uncertain due to the discrepancies in the saturation-carrying capacity estimated by different correlations. The effect of riser diameter on G s was discussed, including the dimension of D t , ind , beyond which the circulating rate was suggested to be independent of the riser diameter. Comparison of estimated and experimental results of P up . • Five field tests on the circulating rate G s are conducted in a 550 MWe CFB boiler. • Both correlations of K ∞ ∗ and G s ∗ are adopted to estimate the circulating rate. • Correlation of K ∞ ∗ (Colakyan & Levenspiel) shows best agreement with experiments. • Fluidization velocity is found to be higher than transition velocity. • Effect of riser diameter on estimating G s are found to be significant.