Condensing steam turbine systems

The figure presented here illustrates a system where the back-end of the turbine is operated under vacuum conditions.

In such a system, steam for the thermal load is obtained by extraction from one or more intermediate stages at the appropriate pressure and temperature. The remaining steam is exhausted to vacuum conditions existing in the condenser. In this system a considerable amount of heat is wasted in the cooling circuit provided to cool the condenser.

In comparison to the back-pressure system, the condensing unit has a higher capital cost and, in general, a lower total efficiency.