Coal-fired steam generator with heating surfaces above the firing or combustion chamber

In a coal-fired steam generator wherein tubes forming heating surfaces are suspended above a firing chamber from support tubes that extend in a given direction and are mutually spaced apart, transversely to the longitudinal axis of the tubes forming the heating surfaces, a distance that is less than the mutual spacing of the support tubes in the direction of the longitudinal axis of the tubes forming the heating surfaces, the improvement therein comprising, an initial bend in a plane wherein the support tubes are mutually spaced apart by said lesser distance being formed in the support tubes located below the lowermost of the tubes forming the heating surfaces suspended therefrom, and further bends provided in the support tubes and forming auxiliary heating surfaces extending substantially perpendicular to the given direction in which said support tubes extend, the mutual spacing between said auxiliary heating surfaces formed from the support tubes being equal to the mutual spacing between the support tubes in direction of the longitudinal axis of the tubes forming the heating surfaces and suspended from the support tubes.