Flue gas desulfurization under simulated oxyfiring fluidized bed combustion conditions: The influence of limestone attrition and fragmentation

Flue gasdesulfurizationbymeansoflimestoneinjectionundersimulatedfluidizedbedoxyfiringcondi- tions wasinvestigated,withaparticularfocusonparticleattritionandfragmentationphenomena.An experimental protocolwasapplied,basedontheuseofcomplementarytechniquesthathadbeenprevi- ously developedforthecharacterizationofattritionofsorbentsinair-blownatmosphericfluidizedbed combustors. Theextentandpatternoflimestoneattritionbysurfacewearinthedensephaseofaflu- idized bedwereassessedinbenchscalefluidizedbedexperimentsundersimulatedoxyfiringconditions. Sorbent samplesgeneratedduringtheoxyfiringtestswerefurthercharacterizedfromthestandpoint of fragmentationuponhighvelocityimpactbymeansofaparticleimpactor.Theexperimentalresults were comparedwiththosepreviouslyobtainedwiththesamelimestoneunderair-blownatmospheric fluidized bedcombustionconditions.Theprofounddifferencesintheattritionandfragmentationextents and patternsassociatedwithoxyfiringascomparedtoair-blownatmosphericcombustionandtherole played bythedifferentattrition/fragmentationpathswerehighlighted.Inparticular,itwasnotedthat attrition couldeffectivelyenhanceparticlesulfationunderoxyfiringconditionsbycontinuouslydisclosing unconverted calciumtothesulfur-bearingatmosphere.