ASSESSMENT OF A MODEL WITH CHAR ATTRITION FOR A BUBBLING ATMOSPHERIC FLUIDIZED-BED COMBUSTOR

Abstract

A comprehensive model, previously developed and tested for prediction of behavior of continuous fluidized-bed combustors, is extended to incorporate char attrition and is applied to the simulation of a 0.3 MegaWatt (MW) atmospheric bubbling fluidized-bed combustor burning lignites with high Volatile Matter/Fixed Carbon (VM/FC) ratios in their own ashes. The effect of this incorporation is assessed by comparing the predictions of the model with and without attrition with measurements. Favorable comparisons obtained between predicted and measured temperature and concentration profiles and carryover char particle size distributions imply that these parameters are not sensitive to char attrition for lignites and the operating conditions under consideration. However, comparisons between combustion efficiencies predicted with and without char attrition and those obtained from measurements show that consideration of char attrition is essential for accurate prediction of combustion efficiencies.

Keywords:

• fluidized-bed combustion
• char attrition
• lignite