| 摘要 |
The invention relates to a steam generator, preferably a forced-throughflow steam generator, with a feed water preheater and, arranged on the flue-gas side between boiler outlet and air heating inlet, a catalytic converter for nitrogen oxide reduction, and with, arranged between the outlet collector of the feed water preheater and the inlet into the evaporator heating surfaces, a mixing point in the form of a connection pipe. In order, under all load conditions of the steam generator, to prevent the temperature falling below the level of the flue gases supplied to the catalytic converter, there is arranged in the feed water line leading to the inlet collector of the feed water preheater a three-way valve, from which a branch line leads to the lower part of the mixing point. Moreover, the upper part of the mixing point is connected via a control valve and a steam line to the superheater. The three-way valve can be controlled by a temperature sensor arranged in front of the catalytic converter in the flue gas duct. The control valve in the steam line is controlled by a water level regulation in the mixing point.
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