Residence time distribution of gas in the fluidized bed in a rotating drum.

Abstract

When a tumbling particle bed in a horizontal rotating drum is aerated, the particle bed can be considered as a gas fluidized bed, which may be called a fluidized bed in rotating drum (FBRD).Measurement of the residence time distribution (RTD) of gas in an FBRD of coarse particles was carried out by the stimulus-response method using a bench-scale rig. The concentration change of nonadsorbing tracer gas (methane) in the exit stream, as the response to a pulse input, was measured by a flame ionization detector connected with PC data acquisition system.The results of the experiments revealed that the RTD of gas was affected by the parameter ξ, which included aeration rate and rotation speed of drum, and aeration angle. Backmixing of gas was found for large ξ. The reactor efficiency, calculated from the real RTD functions, was close to that of the packed bed and was distinctly higher than that of the conventional bubbling fluidized bed for small ξ. Finally, the reactor efficiency of the FBRD was represented in terms of parameter ξ.