At the roof looking northeast

At the roof of the boilerroom of unit EC 7 looking into the direction of unit EC 20. At left: the bypass stacks of the 5 units. these stacks were originally meant te be used as a bypass when the main valves in the fluegass outlets of the boilers were closed during standstill.
In that way the standstill loss would be minimized.
But: during startup of the unit we have to vent the boiler (regulations) to be sure no natural gas is present when the gasturbine ignites so the efficiency is not enough.

Nowadays we only use them rarely, only when we have to cooldown the boiler for maintenance; in that case we keep the main fluegasvalves open, open the bypass and due to the draft in the boiler we "suck" cold ambient air in and that cools down the boiler...

Better in LARGE....