May 16-21, 2010
Gas mixing in a tall narrow fluidized bed operated in the slugging fluidization regime is studied with the aid of computational fluid dynamics. Three-dimensional numerical simulations are performed with an Eulerian-Eulerian model. Predicted axial and radial tracer concentration profiles for various operating conditions are generally in good agreement with experimental data from the literature. Different field variables including voidage, tracer concentration, and gas velocity at upstream and downstream levels are analysed to study gas mixing. Mean tracer concentrations in the dense phase and the bubble phase are evaluated and significant differences between them are found. The time-mean concentration is weighted heavily towards the dense phase concentration which may lead to misinterpretation of sampling data in dispersion models. Caution is needed when interpreting time-mean tracer concentration data. A flux-based mean tracer concentration is introduced to characterize the gas mixing in numerical simulations of two-phase fluidized beds.
John Grace, Tingwen Li, Yongmin Zhang, and Xiaotao Bi, "NUMERICAL INVESTIGATION OF GAS SAMPLING FROM FLUIDIZED BEDS" in "The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering", Sang Done Kim,Korea Advanced Institute of Science and Technology, Korea; Yong Kang, Chungnam National University, Korea; Jea Keun Lee, Pukyong National University, Korea; Yong Chil Seo, Yonsei University, Korea Eds, ECI Symposium Series, (2010). http://dc.engconfintl.org/fluidization_xiii/23