
Simply, if a retort filled with a high grade (particle size
and purity) of aluminium oxide
and is then subjected to any combination of process gases at the correct flow
and pressure,
the oxide will exhibit similar characteristics to that of a fluid, hence the
name fluidised bed.
The gas flow within the bed must be accurately controlled and
uniformly distributed, this is
perhaps the most critical aspect of fluid bed operation. Gas flow is
controlled by the
'fluidisation plate' which is situated at the base of the retort, correct flow
will produce +/- 2oC
throughout the 'process envelope'.
Below graphically demonstrates the principals.
Fluidisation Plate Aluminium Oxide

Gas Flow Fluidisation of Oxide Oxide reacts similar to a liquid

'Liquid' oxide allows the placing
The component is heated
of components within the bed
and recovers to bed temperature

The graph below shows typical harden and double temper heat treatment cycle using a fluidised bed