Simulation and experimental study on the motion of non-reacting objects in the freeboard of a fluidized bed

Abstract

The motion of a large non-reacting object in the freeboard of a bubbling fluidized bed was characterized experimentally and compared with Monte Carlo simulations. A tracking technique was developed to study the object motion both when it is immersed in the dense bed and in the freeboard. Monte Carlo simulations, based on the kinematic equations of the motion, and relying on a minimum set of experimental data, were used to obtain the relevant characteristics of the process.

The non-reacting object motion in the freeboard is only affected by gravity and can be described as a ballistic motion, characterized by the initial velocity of the object, or ejection velocity. The ejection velocity modulus and angle were experimentally determined for several conditions, varying the gas velocity and the bed height. The results showed a good correlation between the ejection velocity and the bubble velocity. Probability distributions for the modulus and angle of the ejection velocity were obtained from the experimental data.

The object lateral displacement and the time spent by the object in the freeboard were calculated using three parallel approaches, with different degrees of simplicity and accuracy, employing the Monte Carlo model. The results of the model were compared to the experimental results, showing a good agreement.