Measuring and calculating solid carry over in a CFB cold flow model for different materials

The goal of the paper is to demonstrate the importance of particle characterization when the solid carry over of a circulating fluidized bed (CFB) is to be calculated quantitatively. This is of practical relevance when theoretical models are applied to real processes or in process design tools. Therefore, the solid carry over of three materials different in particle size, particle size distribution and in particle shape have been studied in a CFB cold flow model. Plotting the solid carry over as function of gas velocity shows that measured and calculated curves have the same shape. But, generally, both curves are shifted and the shift depends on the particle size taken for the calculations. For that reason, an equivalent particle diameter was calculated by fitting the calculations to the measurements. These CFB-equivalent particle sizes were compared with the particle sizes resulting from other measurement methods such as sieving analysis, laser diffraction and fluidization experiments.