Combustion device and a method for combusting granular, solid fuel

A combustion device for combusting granular solid fuel, said combustion device comprising:

• a chamber having an outer wall and an inner wall, which inner wall divides an inner space of said chamber into a combustion air space and a combustion chamber,
• at least one blast apparatus for providing combustion air, and
• rotating means for rotating said combustion chamber,
• wherein said inner surface of said combustion chamber comprises a number of steps for lifting combustion fuel in said combustion chamber, and
• at least one aperture is provided through at least one step for directing a primary combustion air into said combustion chamber in a direction substantially parallel to and/or along a circumference of said combustion chamber for contributing combustion of combustion fuel and for moving said combustion fuel on said steps,
• and said combustion chamber comprises at least one aperture for providing a secondary combustion air into said combustion chamber in a direction substantially parallel to a rotation axis of said combustion chamber for removing completely combusted fuel and optionally combustion gases from said combustion chamber,
• wherein the rotating movement of the combustion chamber provided by said rotating means and said primary combustion air together elevate completely combusted fuel into said secondary combustion air in order to be removed from said combustion chamber.