the de aerating space when providing its traditional function that the de aerating circular line integrated in the de aerating structural component 14 and the associated upright protruding de aerating rack pipe enable the draining of cooling water from the triangular cooling units in the second preferred embodiment shown in fig4 the vacuum line 20 is coupled to the de aerating space i e preferably to the rack pipe above the water level that prevails in case of vacuum maintenance in the de aerating space putting the system under vacuum draining is implemented as described above by the appropriate control of the vacuum tight valves 19 and the exhaust valve 21 the vacuum line 20 subjects suction effect to the de aerating rack pipe which raises the height of the water column in the rack pipe the de aerating structural component 14 as well as the rack pipe preferably integrated therein should be installed at such a height that the suction effect does not yet draw the cooling water into the steam condenser shell of the direct contact condenser 11 it is easy to see that the solution according to the invention may be combined also with an approach whereby the water level in the direct contact condenser 11 is raised such an approach is shown in fig5 where for the sake of simplicity the vacuum i e the subatmospheric pressure generating unit is not shown with the water level of the direct contact condenser 11 being hence raised the extra elevating height drop evolving in the return branch of the cooling system can be reduced or even eliminated in the given case this approach can be applied especially in the case of the steam turbines 10 having a lateral axial or upward outflow the water level of the.