Dealkalization by a Novel Flue Gas Enhanced Water Leaching Method and Fouling/Slagging Behavior of High AAEM Coal
Severe slagging and fouling issues of Xinjiang's high alkali coal hindered its large-scale use in power generation.In this study,based on the theory that the carbonic acid formed by the dissolved CO2 can effectively remove water-insoluble alkali and alkaline earth metals(AAEM)from coal,a hot flue gas-enhanced water leaching(FG-WL)method was proposed for AAEM re-moval from high alkali coals using the flue gas as the CO2 source.Results showed that the removal rate of Na and Ca from several typical Xinjiang high alkali coals reached 90%and 45%,respec-tively,which were significantly better than those from conventional water leaching.Moreover,the alkali-to-acid ratio(B/A)of leached coal ashes were remarkably reduced,the ash melting points were increased by about 150℃,and the tendency of slagging and fouling of coals obviously inhib-ited from the Severe to Moderate,or from the Moderate to Non-slagging after FG-WL treatment.Therefore,the FG-WL method was proven effective in AAEM removal and inhibiting the slagging and fouling risks from high alkali coals.Furthermore,the simplicity and feasibility of this method make it an ideal solution for utilizing power plant flue gases,holding great economic and social significance.
high alkali coalhot flue gascoal leachingslagging and fouling