The effect of gas viscosity on the agglomerate particulate fluidization state of fine and ultrafine particles

Gas-fluidized fine particles agglomerate in a state of homogeneous, nonbubbling fluidization, so-called agglomerate particulate fluidization (APF). We analyze the role of gas viscosity on the APF state. Our results indicate that there is no relevant distinction between the agglomerates fluidized with different gases. However it is seen that a relatively small increment of gas viscosity opens up a new window of highly expanded APF state with delayed onset of bubbling. In the case of sufficiently high viscosity and/or small enough particle size we observe full suppression of the bubbling regime. For nanoparticles exhibiting agglomerate bubbling fiuidization (ABF) behavior where bed expansion is small and bubbling occurs soon after minimum fiuidization, we also observe a delayed onset of bubbling when fluidizing with a gas of higher viscosity.