Burner for solid and liquid or gaseous fuel

Burner for feeding solid and liquid or gaseous fuel into a burning zone of a kiln, for instance a rotary kiln, the burner comprising an outer casing inside which is mounted a central fuel feed channel for liquid and/or gaseous fuel, a first concentric channel for feeding combustion air in the form of primary air into the burning zone and surrounding the central tube, a second concentric channel surrounding the first concentric channel and adapted for feeding pneumatically a solid fuel into the burning zone, and mounted outside of and surrounding the second concentric channel a plurality of annularly spaced ducts for feeding an amount of combustion air into the burning zone, characterized in that said plurality of annularly spaced ducts also form a heat exchanger for heating the combustion air being transported through said plurality of ducts by heat exchange with heat generated in that part of the kiln into which the burner extends, and in that the plurality of ducts is separated from the second concentric channel by a heat insulating ceramic layer or layer of light fibre material.