Abstract
For the continuous operation in a multi-stage fluidized bed, it is important to find the region of the operating conditions for stable fluidization and the dynamic characteristics in this region.
In this work, the dynamic characteristics of a simple apparatus, that is, a single-stage fluidized bed is investigated instead of a multi-stage one. The types of a single-stage fluidized bed used are the fluidized bed both without and with a downcomer equipped with an orifice.
The transient responses for the discharging rate of solid particles are examined, when the feed rate of solid particles is changed stepwise. The fluidized particles used is glass beads (Dp=154μm, ρs=2.50g/cm3, umf=2.2cm/s). The transient responses for the discharge of solids are estimated by developing from the experimental correlations in steady states. The estimated values are agreement with the experimentally measured transients.
It is found that the transient responses in both types of fluidized beds can be shown approximately by the first order lag. The time constant in a fluidized bed with a downcomer equipped with an orifice is recognized to be shorter than that without a downcomer.
