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標題: Effects of Agglomeration Processes on the Emission Characteristics of Heavy Metals under Different Waste Compositions and the Addition of Al and Ca Inhibitors in Fluidized Bed Incineration
作者: Kuo, J.H.
Lin, C.L.
Wey, M.Y.
關鍵字: particle-size distributions;low-rank coals;high-temperature;ash;agglomeration;biomass ash;combustion;defluidization;pollutants;kaolin;defluidisation
Project: Energy & Fuels
期刊/報告no:: Energy & Fuels, Volume 23, Page(s) 4325-4336.
The agglomeration that occurs in a fluidized bed incineration system results in the unexpected shutdown of the system and causes secondary polluants such as heavy metal to be generated. Addition of Al and Ca-based additives is an efficient method to control the particle agglomeration. However, emission behavior of heavy metals in inciricration processes could be influenced by the addition of agglomeration inhibitors due to both chemical reaction with metals and the fluidization behavior being changed. Accordingly, the aim of this study is to show the emission characteristies of heavy metals (Pb, Cr, and Cd) under various waste compositions (Cl and S) and the addition of agglomeration inhibitors (Al and Ca) during the defluidization process. A thermodynamic equilibrium simulation wits used to predict heavy metal formation and to compare the experimental results. The results showed that the emission concentration of heavy metals increased as a result of the reduction of combustion efficiency caused by Al and Ca during agglomeration inhibition processes. In particular, the heavy metal Cr vaporized easily at the initial stage of the defluidization process, indicating that the chemical reactions changed between Na and Cr by adding At into the system at high temperature. The different affinities of both Al and Cr reacting with Na in the fluidized bed were considered the main reason for the Cr emission. Oil the other hand, when the wastes contained Cl, the emission concentration of heavy metals increased because of the formation of low-boiling point metallic chlorides. The addition of Na caused. bed agglomeration and decreased the emission of Cd and Cr, compared to when Cl was added. However, Cl was the dominant factor on heavy metal Pb. The emission concentration of heavy metals also decreased evidently when both Na and S were added during defluidization. The formation of high-boiling point sulfates was observed on the surface of the sand bed while heat energy accumulated during defluidization by Na. Moreover, the results of the thermodynamic equilibrium simulation demonstrated that the Cl content easily reacted with the three heavy metals. In addition, Ca influenced the emissions of metals Pb and Cr; however, Cd was Owed by Al.
ISSN: 0887-0624
DOI: 10.1021/ef9003946
Appears in Collections:環境工程學系所

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