循环流化床固硫灰特性及作水泥混合材应用的研究

中国建筑材料科学研究总院硕士学位论文ABSTRACTThe Circulated Fluidized Bed Combustion (CFBC)ashes are by-products fromthe power plants with CFBC boilers which use sulfur coal and sulfur capture agentsuch as limestone burning and desulfurizing in the boiler at about 900C.As the rapidspread of CFBC technology,the yearly ash output is about 80 million tons andincreases rapidly;as a result,the utilization is urgent.As the development of cementindustry,the cement admixture demand is more and more.The CFBC ash as cementadmixture is one of its important use methods,which has little information and needsmore research.In this paper,the CFBC ash samples from different power plants were studied.The CFBC ash properties were investigated compared with the pulverized coal (PC)fly ash,a modified method was demonstrated to evaluate the reactivity of CFBC ashesand the reactivity origin was analyzed by XRD,SEM,and the feasibility as cementadmixture was initially studied on cement strength,setting time and soundness,compatibility with water-reducing agent and expansion performance,which laysemphasies on the influence of SO3 morphology and content on the cementperformance.The results showed that,compared to the PC fly ash,the CFBC ashes had morecontent of SO3,f-Cao and loss on ignition.The particles of CFBC ashes wereirregular and loose textured.The SO3 existed as anhydrite II-CaSO4,which had thesame structure with natural anhydrite.A modified method of "clinker 28dcompressive strength ratio"was demonstrated to evaluate the reactivity of CFBCashes according to the SO3 content,which showed that CFBC ash reactivity was highwhen the CFBC ash SO3 content was less than 11.6%,satisfing the standardrequiments of PC fly ash used as cement active addition.The anhydrite of CFBC ash could completely replace gypsum to retard theclinker setting time,and the SO3 content should less than 3.5%,otherwise,the SO3soundness was unqualified.With high SO3 content and water requirement content,