Treating the Low Ash Coal Syndrome of CFBs – Integrated Bottom Ash Screening and Recycling in Hot Loop Solids Control
(Room Nile 3)
20 Sep 17
9:00 AM
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10:30 AM
Tracks:
Track C - Optimizing Plant Operation
Bottom ash screening and recycling system for plants using fluidized bed technology. Bed ash recirculation back to the boiler saves costs by reducing consumption of fresh make-up sand and by minimizing the amount of bottom ash. Only the fine-grained portion is returned. Technology is suitable for any kind of solid fuels. Proven experience is highlighted against increasing demand for equipment to handle boiler ash from any type of fuels burned. Importance of bed ash sieving and recycling in South East Asia has increased, while boilers have moved to lower and lower ash content fuels. Lack of fine solids in furnace due too low fuel ash content has created so called "Low ash syndrome" for boiler. When solid inventory is too low, this tends to increase particle size in furnace resulting increased erosion and higher temperatures both in bed and furnace. Mitigating this problem of missing solids by using make-up sand alone results high operation costs and even higher erosion risk, since make-up sand is hard and thus erosive. Solution for this phenomenon is utilization of bed ash sieving and recycling, which returns fine solids back to furnace and increases fine solids inventory in furnace. The result is reduced temperatures and lowered erosion risk.