Patent ID: 7428374

Claim:
A steam generator, comprising: an evaporator or once-through heating area comprising a number of steam-generator tubes that are connected in parallel and through which a flow medium flows, and configured such that a steam-generator tube that is heated to a greater extent compared with a further steam-generator tube of the same evaporator or once-through heating area has a greater throughput of the flow medium than the further steam-generator tube, wherein the steam generator tubes are disposed within a heating-gas duct; a heating gas that flows in a substantially horizontal direction through the heating gas duct; and a discharge collector that is connected downstream of the steam-generator tubes of the evaporator or once-through heating area on the flow-medium side and is oriented with its longitudinal axis essentially parallel to the heating-gas direction; and a further evaporator or once-through heating area disposed on the flow-medium side downstream of the evaporator or once-through heating area, wherein steam-generator tubes forming the further evaporator or once-through heating area each have a downtake section which is disposed approximately vertically and through which the flow medium can flow in a downward direction, the downtake section is connected by an overflow section to an uptake section which is connected downstream of said downtake section on the flow-medium side, and which is disposed approximately vertically and through which the flow medium can flow in an upward direction.