1、附录 外文文献及翻译 Utilization of CFB Fly Ash for Construction Applications R. E. Conn and K. Sellakumar Foster Wheeler Development Corporation Livingston, NJ A. E. Bland Western Research Institute Laramie, WY ABSTRACT Disposal in landfills has been the most common means of handling ash in circulating fluid
2、ized bed (CFB) boiler power plants. Recently, larger CFB boilers with generating capacities up to 300 MWe are currently being planned, resulting in increased volumes and disposal cost of ash byproduct. Studies have shown that CFB ashes do not pose environmental concerns that should significantly lim
3、it their potential utilization. Many uses of CFB ash are being investigated by Foster Wheeler, which can provide more cost-effective ash management. Construction applications have been identified as one of the major uses for CFB ashes. Typically, CFB ash cannot be used as a cement replacement in con
4、crete due to its unacceptably high sulfur content. However, CFB ashes can be used for other construction applications that require less stringent specifications including soil stabilization, road base, structural fill, and synthetic aggregate. In this study, potential construction applications were
5、identified for fly ashes from several CFB boilers firing diverse fuels such as petroleum coke, refuse derived fuel (RDF) and coal. The compressive strength of hydrated fly ashes was measured in order to screen their potential for use in various construction applications. Based on the results of this
6、 work, the effects of both ash chemistry and carbon content on utilization potential were ascertained. Actual beneficial uses of ashes evaluated in this study are also discussed. INTRODUCTION CFB combustion has developed into a mature technology for burning a wide range of fuels, while still achievi
7、ng strict air emissions requirements. Typically, fuels are burned in a CFB boiler with the addition of limestone to capture SO2 in a solid form. With larger CFB boilers being brought online, a greater emphasis has been placed on enhanced beneficial use of ash than in the past. Studies have shown tha
8、t the environmental impact from CFB ashes is less than those from p.c. ashes and should not limit their utilization as marketable by-products (Conn and Sellakumar, 1997； Young, 1996). Traditionally, p.c. fly ash has often been sold for use as an admixture in the production of Portland cement. The ut
9、ilization options for CFB ashes are somewhat more diverse than p.c. ash, due to the effect of sorbent (calcium) on the overall ash chemistry. These options include agricultural applications, construction applications and waste treatment. Beneficial use for construction purposes is one of the most co
10、mmon markets for CFB ash. These uses include soil stabilization, road base, structural fills, and synthetic aggregate. To qualify for these uses, the ash must have special properties and pass certain ASTM tests. Compressive strength is one of the most important physical properties a material must po
11、ssess when being considered for different construction applications. Depending upon the specific application, different degrees of compressive strength are required. In this study, the unconfined compressive strength was measured for hydrated CFB fly ashes from boilers firing a wide range of fuels.
12、These results provided a indication of potential construction uses for fly ashes with very different compositions. The specific objectives of this work were: CHARACTERIZATION OF FLY ASHES Nine fly ashes evaluated in this study were obtained from CFB boilers firing diverse fuels such as bituminous go
13、b (0.5% S), low volatile bituminous coal (0.3% S), high sulfur (4.7%) bituminous coal, petroleum coke (5.0% S), and RDF (0.3% S). The fly ashes had significantly different chemical compositions as would be expected considering the types of fuels being fired. The bituminous gob fly ash was composed primarily of coal ash since it was taken from a boiler that does not use limestone injection for sulfur capture.
