3. Combined cycle without afterburner

3.1 Rehabilitation

The rehabilitation of a power plant by STAG normally involves replacing the old steam boiler with one or more "gas turbine – recovery boiler" units. This is justified primarily by the fact that the service life of a steam turbine is generally longer than that of a boiler, particularly when the latter is fired by coal.

The expected effect of this type of rehabilitation is an increase in the efficiency of primary energy use, up to values close to those corresponding to STAG.

However, such rehabilitation poses several problems:

• using a recovery boiler (RC) with several pressure levels means finding values for these pressures that are compatible with the existing steam turbine....