Integrated modeling methodology for ash agglomeration in poly-disperse fluidized beds using particle population framework

This paper discusses a unique agglomeration modeling methodology developed based on binary collisions to combine the effects of heterogeneity in ash chemistry and granular physics. A simple population balance is defined to find changes in the particle size distribution (PSD) of a fluidized bed. Thermodynamic equilibrium calculations and a computational fluid dynamics (CFD) code, are used to obtain hydrodynamic parameters. A method to calculate and use a distribution of collision frequencies in fluidized beds, corresponding to a poly-disperse particle size distribution, was developed in order to incorporate the particle level heterogeneities. A distribution of collision frequencies obtained for poly-dispersed particles showed a three orders of magnitude higher collision frequency amongst the smaller particles than the coarser ones, at the initiation of agglomeration. Ash agglomeration occurred when the slag amount (binder) was less than 10 wt% at temperatures <850 degrees C for Pittsburgh No. 8 coal. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study discusses a unique agglomeration modeling methodology based on binary collisions to analyze the effects of heterogeneity in ash chemistry and granular physics. By utilizing methods such as population balance and thermodynamic equilibrium calculations, changes in particle size distribution (PSD) in fluidized beds were determined. The results show that ash agglomeration is most effective at temperatures below 850 degrees C when the binder content is low.