Disposal, Recycle, and Utilization of Modified Fly Ash from Hydrated Lime Injection into Coal-Fired Utility Boilers

摘要

The paper gives results of an assessment of the disposal, utilization, and recycle os a modified fly ash from the injection of hydrated lime into a coal-fired utility boiler. The process, developed as a low-cost alternative for achieving moderate degrees of SO2 control at coal-fired power plants, is being demonstrated in a 105-MW, coal-fired utility boiler at the Edgewater Station of Ohio Edison Company. Both the laboratory tests and the large-scale disposal study showed that the modified ash can be safely handled and landfilled. The studies showed that the cementitious reactions within the wetted ash can produce a nearly impermeable material, if the ash is properly conditioned and placed. One of the most promising utilization concepts appears to be synthetic aggregate production for bituminous pavement applications. One of the most promising recycle concepts appears to be the use of coarse limestone injection with cyclonic removal of the coarse calcine particles followed by hydration and reinjection. This effectively yields the performance of hydrated lime at the cost of coarse limestone, which is much less expensive.