Investigation on a single char particle movement behavior in a bubbling fluidized bed under high temperature

The movement behavior of fuel particles in a fluidized bed combustor plays a decisive role in heat and mass transfer, thus affecting the combustion process and pollutant emission. We presented a CFD-DEM framework to investigate the movement behavior of a single char particle and carried out a series of experiments in a visualized fluidized bed to validate the model reliability. The char particle movement behavior under high temperature was evaluated quantitatively by new metrics. The force on a single char particle was obtained under different bed heights. The relationship between the force and movement behavior was studied through theoretical calculation. Finally, the effect of operation parameters, such as superficial velocity and temperature on the movement behavior and combustion were investigated. The force on the char particle was observed to increase exponentially along the bed height. Gravity indicated a more remarkable influence on movement behavior in the splash zone, while the pressure gradient force and collision force were the governing factors in the dense phase. The char particle was dominated by all the forces once moving to the bed surface. The char particle movement behavior was effect under the joint action of bubbles and kinetic energy of bed material particles.

Automated summary

In this study, the movement behavior of a single char particle in a fluidized bed was investigated using a CFD-DEM framework, and the reliability of the model was validated through experiments. It was found that the movement of the char particle was influenced by various forces, such as gravity, pressure gradient force, and collision force, and the force increased exponentially along the bed height. The findings provide guidance for optimizing the design and operation parameters of fluidized bed combustors.