fluidized bed

Short definition from Wiktionary

Noun

1. 1
   An industrial unit process in which a quantity of a solid particulate substance is caused to float in a stream of a fluid (usually air or other gas) in order to create conditions in which many chemical, combustion and drying reactions take place efficiently.
2. 2
   A reactor vessel or other piece of equipment in which a substance is maintained in the fluidized state. In this context, often used attributively.