Subcritical pressure high-temperature steam power plant and subcritical pressure high-temperature variable pressure operation once-through boiler

A subcritical pressure high-temperature steam power plant comprising:

• a combustion boiler system;
• a steam turbine generator system;
• and
• a condensate and feedwater system,
• the subcritical pressure high-temperature steam power plant having a rated output in a range of 0.1 million kW to 0.4 million kW,
• the combustion boiler system including a high-temperature superheater configured to supply superheated steam with steam conditions of subcritical pressure and 593° C. or more, the subcritical pressure being 16.6 MPa or more, and a high-temperature reheater configured to supply reheated steam with steam conditions of 593° C. or more, and
• the steam turbine generator system including a high-pressure steam turbine provided with an initial blade cascade having a height and shape, the high-pressure steam turbine with the initial blade cascade being configured to be driven by the superheated steam with the steam conditions of subcritical pressure of 16.6 MPa or more and 593° C. or more and a reheat intermediate-pressure steam turbine to be driven by the reheated steam with the steam conditions of 593° C. or more.