The roaster family based on this concept uses a unique fluidized bed with amazing properties. This new type of fluidized bed is called "revolving wave". While the major part of the coffee is resting, just slightly lifted by the roasting air from below, the beans in the shallow part of the bed are moved fast by the heating air, removing the beans on the one side of the resting bed and depositing them on the other.
The result is a "wave" revolving every 5 to 10 seconds in the ring-shaped roasting chamber. The fluidized bed part of this process roasts the coffee selectively by size and density because the lighter beans are moved on top of the resting bed where it is cooler, producing a more homogeneous roasting result.

The new roasting process resembles the coffee movement in a drum roaster, but it inherited the low roasting temperatures and short roasting times from its convectional ancestors (approx. 270 °C / 520 °F at 3 minutes roasting time for the maximum batch size).

 

In contrast to some purely convective roasters it is possible to use longer roasting times without reducing the temperatures too much. The NEPRO ROTOTERM® combines the benefits of both worlds: convectional and contact heat transfer.