This type of scrubber has a stationary filling either loosely "sprinkled" (it can also be stacked, either partially or in the whole volume) – rings, saddles, balls, or structural – large area blocks. It is used for fumes without solid particles and a for variable gas flow.
A fluidized bed – most often balls - TCA washers, (Turbulent Contact Absorption), are suitable for "dusty" air mass and situations in which absorption occurs quite readily. These washing systems have a smaller size – refer to both photos on the home page, they are rather reminiscent of towers.
The trend over recent years has been for packed scrubbers with a structured packing and high liquid hold-up towers.