E ect of coal particle size distribution on agglomerate formation in a ¯uidized bed combustor (FBC)

Abstract

An investigation was conducted to ®nd out the reasons for agglomeration in a ¯uidized bed combustion (FBC) power plant. Two typical coal samples were collected for investigation. The ®rst sample was collected when the plant was operating smoothly, and the second was collected immediately after agglomeration. These two samples were subjected to analysis. It was observed that agglomeration of the bed material in FBC plants takes place when the coal sample contains either too many very ®ne particles or too many very coarse particles or both in very large proportion. The very ®ne particles present in the coal have considerable plastic properties (caking and swelling tendency) which cause agglomeration. The coarser particles are denser because of their higher ash content, and their higher density causes an increase in minimum ¯uidization velocity which, in turn, leads to agglomeration and de¯uidization. Medium size coal particles are most suitable for combustion in a FBC.