Experimental observation of pressure waves in gas-solids fluidized beds

Pressure waves in gas-solids fluidized beds are generally investigated to characterize gas bubble dynamics, which are important for reactor performance. In literature the origin, propagation and attenuation ofpressure waves in gas-solids fluidized beds is still subject of discussion. For Geldart group B particles, pressure waves generated by a gas pulse are characterized as compression waves propagating at velocities of 10 m/s and higher, in agreement with results by Bi et al. [2] The attenuation ofupward traveling pressure waves is determined by the distance ofthe origin ofthe wave to the bed surface. Downward traveling pressure waves are not attenuated. In freely bubbling beds a major source offast pressure waves is bubble coalescence, which generates pressure waves traveling upwards and downwards. The average pressure wave propagation velocity in circulating fluidized beds is adequately predicted by the pseudo-homogeneous flow rnodelfor voidages above 0.6