Once-through steam generator having spirally disposed evaporator tubes

摘要

A once-through steam generator includes a gas flue formed of steam generator tubes welded to one another in a gas-tight manner through fins. The steam generator tubes are connected in parallel for the throughflow of a flow medium, they have a surface structure on their inside for generating a high flow turbulence in the medium flowing through them and they are disposed approximately in a spiral coil in a firing region of the gas flue. The steam generator tubes are constructed in such a way that, when they are in operation, the geodetic pressure loss of the medium flowing through them is at least 0.5 times their pressure loss due to friction. This ensures that such a once-through steam generator can also be operated in low load states of, for example, about 20% of the design load, without excessive thermal stresses occurring.