Three-Dimensional Eulerian鈥揈ulerian Modeling of Gaseous Pollutant Emissions from Circulating Fluidized-Bed Combustors

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• 作者：Jun Xie ; Wenqi Zhong ; Baosheng Jin ; Yingjuan Shao ; Hao Liu
• 刊名：Energy & Fuels
• 出版年：2014
• 出版时间：August 21, 2014
• 年：2014
• 卷：28
• 期：8
• 页码：5523-5533
• 全文大小：745K
• ISSN：1520-5029

文摘

In this paper, a three-dimensional numerical model has been developed to study the gaseous pollutant emissions during the circulating fluidized-bed (CFB) combustion of combustible solid waste. On the basis of the Eulerian鈥揈ulerian approach, the gas phase is modeled with a k鈥撐?turbulent model and the particle phase is modeled with a kinetic theory of granular flow. The hydrodynamics, heat and mass transfer, and chemical reactions are simultaneously taken into account. Reactions during combustion consist of waste devolatilization, volatile combustion, char combustion, SO₂ formation and recapture by calcium oxide, NO and N₂O formation, and diminution by heterogeneous and homogeneous reactions. The model has been applied to the CFB riser with a height of 1.8 m and a diameter of 0.125 m at atmosphere. The influences of an excess air ratio on the emissions of SO₂, NO, and N₂O are studied. The model predicts a growth in the SO₂ emission when excess air increases. The emissions of NO and N₂O also gradually increase with the increasing excess air ratio. Meanwhile, the CO and CH₄ concentrations show a decreasing tendency. The distribution of the bed voidage, flow pattern development, profiles of gas compositions, and related reaction rates inside the riser are also discussed.