Regenerative thermal oxidizers
Regenerative thermal oxidizers consist of several vertical prism towers, partially filled with ceramic material, and an oxidation chamber which joins the towers.
The gas flow goes through one tower and absorbs energy from the filling (heated in prior cycles). These gases reach the oxidation chamber where the reaction takes place. Afterwards they go through another tower giving off heat to the filling.
Several watertight valves switch cyclically in a way that allows the gas to enter always through a warm bed.
The inversion of the flux direction would cause a little waste gas emission through the stack. In order to avoid this, a third tower takes part in the purge process by re-circulating a bit of flow to the fan.