Numerical Simulation Of Oxy-fuel Combustion In Fluidized Bed Reactor

Oxy fuel combustion is developed to mitigate climate change resulted from CO2 emission. This thesis is a preliminary work for developing a comprehensive combustion model of a pilot BFB. An Eulerian-Eulerian approach for gas-solid phase, combined with the Kinetic Theory of Granular Flow, has been adopted. Coal combustion model is mostly based on classical Arrhenius expression. For heterogeneous reaction include mass diffusion resistance between gas and particle in addition represented by a simple model?effectiveness factor. The simulation results are compared with experiment and a published model prediction.Cold flow simulation with influence of jet and turbulence model is implemented. In both models, bubbles periodically produce, grow up, coalesce and break up regularly. In model with jet, pressure drop and bed expansion is both smaller than model without jet, while uniformity of bubbles and local gas velocity is enhanced. Meanwhile, the volume of bubbles and the magnitude of pressure fluctuation is decreased. With the influence of turbulence model, pressure drop increases and solid becomes more disordered.Reaction simulation with influence of turbulence model is also implemented. As a result, it increases pressure drop and presents a qualitative good agreement with experiments. Therefore turbulence model should be enabled. According to reaction rate, devolatilization rate is set to be bigger comparing with the experiment, while homogeneous reaction rate is set to be smaller comparing with the experiment. In the next simulation, all these reaction rate should be adjusted. After modification according to the analysis, we get access to the perfect result.