Performance evaluation of a fluidized bed reactor by studying the hydrodynamics and thermal properties of different solid particles

In recent years, fluidized bed reactors have been widely used due to the uniform temperature distribution, good mixing of phases and high heat transfer rate. High heat transfer rate in fluidized beds is attributed to hydrodynamic mechanism. Therefore, in this research the important hydrodynamic parameters such as the minimum fluidization velocity, pressure drop, bed height, bubble formation and flow regime are investigated experimentally and numerically by using a two-fluid model coupled with the kinetic theory of granular flow and two different drag models of Gidaspow and Syamlal-O'Brien. The results showed that the numerical results with Gidaspow drag model are in better agreement with experimental results in comparison with the Syamlal-O'Brien drag model. So, the minimum fluidization velocity with an approximate error of 13.8% and the bed height with an average error of 9% are predictable in comparison with the experiments. Furthermore, in order to investigate the effects of particles density and thermal diffusivity on temperature distribution of a bubbling fluidized bed, particles with the same density and different thermal diffusivity coefficients and also solid particles with equal thermal diffusivity and different densities were investigated. Finally, to demonstrate the advantages of fluidized beds to receive the required hot air in industrial units, the temperature distribution in a bubbling fluidized bed was compared with the air temperature in a similar constant surface temperature simple channel. The results showed that the outlet air temperature of a bubbling fluidized bed is about 28 degrees higher than the air temperature in a similar simple channel.