The internal dryer (ID) is a single shaft paddle dryer that operates inside the incinerator. The paddle shaft rotates in a trough, called a bedstone. These bedstones are made of a special kind of refractory material which keeps its shape, so the paddle shaft can receive wet waste and dry it in the furnace. The ID is located within the incinerator’s primary chamber.
Wet waste with a 20% dry solid content, containing either food waste, bio waste or a combination of both, is fed from a silo into the internal dryer. The paddles create a large surface area for the wet waste, improving the drying rate. The ID dries and burns the wet waste using excess energy created by the burning of dry waste and sludge oil.
The internal dryer incorporates a paddle screw featuring variable rotational speed, a design which ensures optimal waste mixing and heat transfer. After the wet waste has burned all that is left in the internal dryer is ash, which ends up in the incinerator ash bed. There is no need for any conveying of dried wet waste or burned waste; it is removed from the incinerator together with the ash from the dry waste.