부산대학교 도서관

Circulating fluid beds pose two challenges for the removal of spent or unreacted calcined limestone and coal ash from the bottom of the bed. The furnace operates under a positive pressure and thus a seal must be maintained between the ambient and the furnace and secondly the bottom ash is discharged at about 1600 F and must be cooled down before transported into a storage silo. In the higher bottom ash-loaded units (firing lignite or anthracite culm) this cooling represents a significant portion of the latent heat lost to the stream generator, thus affecting the overall heat rate. Also the material is abrasive traditionally which has had a negative effect upon the removal system life and maintenance costs. Now there is an alternative to the existing present water screw or auxiliary bed cooler systems applied in the past. This presentation reviews the successful application of a dry bottom ash removal system to pulverized coal (PC) fired units, the experimental and commercial scale developmental work to determine if that PC concept is applicable to Circulating Fluid Bed Units, and projected savings that might be realized if heat recovery, carbon recovery, reduction in parasitic power and maintenance costs all could be improved. The power generation industry typically demands at minimum a commercial demonstration of new technology prior to application and therefore a host site for dry bottom ash removal technology is sought.