Water feedback in vertical forced-flow steam generators

A method for starting up a vertical forced-flow steam generator in a waste-heat steam generator, comprising:

• supplying feed water as a working fluid to the forced-flow steam generator, wherein the working fluid flows firstly through a feed water preheater and then through an evaporator and in the process the working fluid at least partially evaporates,
• supplying the partially evaporated working fluid to a water separation system in which non-evaporated working fluid is separated from evaporated working fluid and is collected,
• wherein the water separation system comprises a separator and a bottle, which are separate containers,
• wherein a return line from the separator opens into a point of connection of the evaporator and a working-medium outlet for the return line in the separator is situated above the point of connection that there is a geodetic return flow of the non-evaporated working fluid into the evaporator via the return line,
• wherein a drain line branches off from the separator and opens into the bottle and is arranged in the water separation system such that it is arranged above the return line,
• wherein at least a portion of the non-evaporated working fluid collected in the water separation system is supplied geodetically to the evaporator,
• wherein one part of the drain line between the separator and the bottle is formed in a siphon-like manner which opens into the bottle, and, in a second part of the drain line, the drain line further comprising a second evacuation line at the drain line's lowest point directly feeding into the bottle without siphon action, wherein the second evacuation line serves to exclusively evacuate the separator, and
• wherein, beyond a specific quantity of accumulating non-evaporated working fluid, a remaining portion is automatically discharged from the water separation system.