a b s t r a c tThe fluidized bed is a technology that involves multiple phases, allowing for efficient contact between them, therefore it is widely used in the chemical industry, metallurgy, oil and thermal power generation. In fluidized bed processes, the gas-solid interactions and chemical reactions generate a large number of variables to be handled, making the process very complex. Therefore, fluidized bed modeling and simulation is widely used to predict and analyze different processes, but it is possible to find in the literature many mathematical correlations that describe this type of flow. Based on this, the present work presents a review of the main mathematical models that describe the behavior of a fluidized bed reactor, and the state of the art regarding the use of modeling and simulation of the bed to predict and analyze different processes. As a result of this review, we can observe the importance of further development of the hydrodynamic modeling of fluidized beds, where understanding the interactions between the phases and the influence of this interaction is crucial for a better understanding and control of the processes. Generating experimental data of gas-solid and solid-solid interactions is also required for the validation of the numerical models.

Bubbling fluidized beds find application mainly in power conversion industries. For design, dimensioning and operation of fluidized bed equipment, the understanding of multiphase gas-solid flows is of great importance. The use of Computational Fluid Dynamics in the simulation of gassolid systems is limited by the complexity of mathematical models, which rely on a series of empirical or theoretical correlations. In the present work, the code MFIX was employed to simulate flows in a bubbling fluidized bed and to compare results predicted using different gas-solid drag Downloaded by [University of Technology Sydney] at 06:08 22 June 2016 2 models. A Two Fluid Model with Kinetic Theory of Granular Flows (TFM-KTGF) was employed, in which gas-solid drag correlations, such as Gidaspow, Hill-Koch-Ladd or Syamlal and O'Brien were applied to model momentum transfer between phases. The results predicted were compared with each other and with experimental results from the literature. It was found that the results predicted using each model differ much. Gidaspow and Hill-Koch-Ladd models yielded bubbles with shapes more similar to the experiments.

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RESUMO -Algumas questões operacionais que envolvem a dessulfuração em leito fluidizado ainda necessitam do desenvolvimento de um maior conhecimento. Dentre elas, destaca-se a relação existente entre as características fluidodinâmicas de operação com a conversão do SO 2 . Para tanto, este trabalho utilizou uma planta piloto de 250 kW t em leito fluidizado borbulhante para a análise da conversão do SO 2 a CaSO 4 com dois distintos tipos de carvão mineral. Foi realizada uma análise estequiométrica e fluidodinâmica do processo a partir de dados obtidos da emissão de SO 2 nos gases de combustão. A % de conversão de SO 2 chegou a 70,5% para um carvão utilizado e 59,5% para outro carvão. O maior teor de enxofre de um dos carvões mostrou influência na extensão da reação, especificamente no número de mols de SO 2 consumidos por hora. A análise mineralógica mostrou que ocorre uma das rotas descritas na literatura com formação intermediária de CaSO 3 por duas reações em série e a elutriação das cinzas e do CaO mostraram distintas tendências.