Characteristics and Performance of Fly Ash from Sodium Sorbent Scrubbing of SO3 Emissions from Coal-Based Power Plants

摘要

Sodium-based reagents are effective in reacting with sulfur trioxide(SO3)and are usedto capture SO3 from flue gas at coal-based power plants.In using sodium-basedreagents to remove SO3 from the flue gas,sodium sulfite and sulfate are formed andthese solid reaction products are incorporated into the particulate stream and collectedwith the fly ash in the primary particulate control device(PCD).There is also potentialfor the sodium-based reagent to react with other components of the gas phase and withash particulates in the flue gas and in the PCD.All of the products of these reactionshave the potential to impact the resulting fly ash and its performance in both disposaland utilization settings.Anecdotal evidence has shown that the fly ash that contains thesodium-based components may have different physical and chemical characteristicsthan fly ash generated without the addition of a sodium-based sorbent.Laboratory evaluations are under way at the Energy&Environmental Research Centerto characterize the chemical composition,physical and engineering performance,andenvironmental performance of a variety of samples collected from full-scale facilitiesutilizing sodium-based sorbents to remove SO3.Preliminary results indicated that thecomposition of the fly ash collected from systems utilizing sodium sorbents to removeSO3 from flue gas varies from baseline fly ash without sodium sorbent but that itsutilization in concrete can continue to be a viable utilization option.