US Patent 10920987 Apparatus and method for burning solid fuel

A solid fuel burning device has at least one burn chamber wall, a burn chamber base, and an interior burn chamber. The burn chamber base is capable of supporting a combustible solid fuel thereon. At least one of the burn chamber walls is radially offset with respect to another of the burn chamber walls. At least two longitudinally extending air inlets are formed in the space between a first longitudinal edge of at least one of the burn chamber walls and a second longitudinal edge of another burn chamber wall. Each of the longitudinally extending air inlets tangentially directs an entry of air into the interior burn chamber to induce an interior swirl of air in the interior burn chamber. The interior swirl of air in the interior burn chamber causes a flame of a combusting solid fuel to swirl in the interior burn chamber.