Effects of the ship motion on gas–solid flow and heat transfer in a circulating fluidized bed

Abstract

Abstract A series of experiments on a circulating fluidized bed (CFB) was performed to investigate the effects of ship motion on gas–solid flow and heat transfer in the CFB. Rolling period, rolling amplitude, inclination angle, superficial velocity, particle diameter range, and solid circulation flux were varied in the experiments. The following results were obtained: (1) When the CFB undergoes rolling motion, the downflow of particles changes periodically and the solid volume fraction increases at the riser bottom. As a result, the time-averaged total pressure drop of the CFB in rolling motion becomes larger than that at the upright attitude. Similarly, the total pressure drop of the CFB at an inclined attitude is larger than that at the upright attitude. (2) The total pressure drop of the CFB in rolling motion is hardly affected by rolling period. As rolling amplitude increases, on the other hand, the effects of rolling motion become more remarkable. From these results, it is concluded that gravity dominantly affects gas–solid flow in the system. (3) At an inclined attitude, the symmetry of the flow field with respect to the riser center plane breaks, and heat transfer at the lower wall of the riser is promoted. As inclination angle increases, heat transfer augmentation becomes more remarkable. Similarly, the heat transfer coefficient in rolling motion is larger than that at the upright attitude. (4) Heat transfer augmentation by ship motion is concluded to be caused by the direct contact between solid particles and the heater surface owing to the vertical component of gravity to the surface.