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

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 Gs 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 Gs 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 Gs was discussed, including the dimension of Dt, ind, beyond which the circulating rate was suggested to be independent of the riser diameter. Comparison of estimated and experimental results of Pup. [Display omitted] •Five field tests on the circulating rate Gs are conducted in a 550 MWe CFB boiler.•Both correlations of K ∞ ∗ and Gs∗ 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 Gs are found to be significant.