Abstract: A heat exchanger tube of a heating boiler, comprising an outer tube, which may be flown through by exhaust gases from the boiler firing and which may be surrounded by boiler water on the outside, and a profiled insert inserted into the outer tube, which comprises ribs running in longitudinal direction of the outer tube to enlarge the inner surface of the outer tube and which is in thermally conductive contact with the outer tube, are to achieve that an even greater heat transfer capacity from the combustion gases to the boiler water in the heating boiler is enabled. A first longitudinal section of the outer tube is formed in a cylindrical, smooth-walled manner and a second longitudinal section of the outer tube has at least one cross-sectional narrowing element narrowing the flow cross section. The profiled insert extends exclusively over the first longitudinal section of the outer tube.

Abstract: In a method for controlling a volume flow of a wetting fluid during adiabatic cooling, an evaporation surface is wetted with the wetting fluid which flows therealong and air to be cooled and/or wetted is directed substantially transversely relative to the flow direction (15) of the wetting fluid the volume flow of the wetting fluid flowing over the evaporation surface is reduced after a predetermined period of wetting of the evaporation surface and, after the volume flow is reduced, temperatures (T1, T2) and/or time/temperature gradients (?T1, ?T2) of the directed air are established at least at two different positions in the flow direction substantially parallel with the evaporation surface, with the volume flow of the wetting fluid being controlled in accordance with the established temperatures (T1, T2) and/or time/temperature gradients (?T1, ?T2).

Abstract: The grate is used for burning a granular fuel material, for instance a biomass material, to be fed onto a loading area of the grate while a primary air feed is coming from below the grate. The grate includes a perforated bed floor having a downwardly-sloping upper surface converging towards a discharge opening where char is concentrated as the granular fuel material is burned during operation. The grate also includes an elongated and bottom-perforated char-receiving conduit positioned immediately under the bed floor. The char-receiving conduit has an inlet end positioned under the discharge opening, and an outlet end that is opposite the inlet end. The char-receiving conduit downwardly slopes between the inlet end and the outlet end. A method of burning a granular fuel material is also disclosed. The proposed concept can increase the overall thermal efficiency of a heat generator and reduce gas and particle emissions in the atmosphere.