F22B1/00—Methods of steam generation characterised by form of heating method
F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
F22B1/18—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines
F22B1/1861—Waste heat boilers with supplementary firing