At this year’s CIBO fluidized bed boiler conference Pat Mongoven presented a summary of Mississippi Lime's work on acid gas removal in fluidized bed boilers. This work has focused on two areas: Dry Sorbent Injection (DSI) for HCl removal; and Furnace Sorbent Injection (FSI) for SO2 reduction.
- Dry Sorbent Injection (DSI) for HCl Removal – Mississippi Lime has developed a High Reactive Hydrated Lime that can react very quickly with HCl in a duct. This is important as the HCl removal is more effective at lower temperatures, and therefore the hydrate should be injected after the air heater. Because of the short residence time between the air heater and the plant's particulate control device, the speed of this reaction is critical. Pilot scale data was presented that compared the reaction time and HCl removal of the new High Reactive Hydrate and Mississippi Lime’s traditional flue gas treatment grade hydrate. The results of several full scale case studies were also presented. The pilot testing and full scale testing demonstrated that High Reactive Hydrate could achieve MATS compliance for HCl removal.
- Furnace Sorbent Injection (FSI) for SO2 Reduction – Another option for fluidized bed boilers is to improve the already existing SO2 removal. Fluidized bed boilers currently inject crushed limestone into the bed for SO2 reduction. Some plants may be able to achieve the lower SO2 levels required by MATS by just feeding more stone. However, this presents challenges by introducing much more mass into the furnace, which then needs to be removed. Mississippi Lime has learned that by injecting hydrated lime into the furnace with the crushed limestone, we can achieve significant additional SO2 removal. In multiple demonstrations we have proven that the addition of hydrate into the furnace allows a unit to operate below the MATS SO2 limits.
Both DSI & FSI present options for fluidized bed boilers that are looking to achieve MATS compliance. Mississippi Lime can help these units achieve MATS compliance by either duct injection for HCl reduction, or furnace injection for additional SO2 reduction. The best economic choice will vary from plant to plant, but both of these technologies have proven themselves as viable compliance options for fluidized bed boilers.
CIBO CFB MATS Compliance 2013
Council of Industrial Boilers (CIBO)