Device for cooling of the cooling fluid of a gas turbine and gas and steam turbine plant with such a device

The coolant cooler (100) for a gas turbine (2) has multiple vapour pipes connected to a gas turbine coolant duct (102). The coolant duct has be contacted by pressurized air from the gas turbine. The vapour pipes can have internal ribbing. A regulator (180) is provided for adjustment of the through flow rate of the feed pipe (112) to the vapour pipes. Claims include a gas and steam turbine using the cooler