Steam turbine plant and control device, and water quality management method for steam turbine plant

A control device for controlling a steam turbine plant,

• the steam turbine plant comprising:
• a chemical supply part configured to supply a pH adjuster to feedwater to a steam generator;
• and
• at least one carbon steel component which includes a pipe or a device formed from carbon steel and through which the feedwater flows, the carbon steel component being configured such that an internal temperature at least partially falls within a range of not less than 120° C. and not greater than 180° C. under load operating condition of the steam turbine plant,
• wherein the control device is configured to, under the load operating condition, adjust the supply amount of the pH adjuster to the feedwater by the chemical supply part such that pH of the feedwater in each of the at least one carbon steel component is not less than 9.8,
• wherein the pH adjuster includes ammonia,
• wherein the steam turbine plant comprises one or more steam drums for temporarily accommodating steam generated by a boiler serving as the steam generator,
• wherein the one or more steam drums include:
• a first drum supplied with the feedwater from a condenser and having a lowest internal pressure among the one or more steam drums;
• and
• a second drum supplied with the feedwater from the condenser not via the first drum and having a higher internal pressure than the first drum,
• wherein the at least one carbon steel component includes the first drum, and
• wherein the control device is configured to, under the load operating condition, adjust the supply amount of the pH adjuster such that pH of the feedwater to be supplied to the first drum is not less than 10.1.

A water quality management method for a steam turbine plant,

• the steam turbine plant including
• at least one carbon steel component which includes a pipe or a device formed from carbon steel and through which feedwater flows, the carbon steel component being configured such that an internal temperature at least partially falls within a range of not less than 120° C. and not greater than 180° C. under a load operating condition of the steam turbine plant,
• the water quality management method comprising:
• a step of supplying a pH adjuster to the feedwater to a steam generator;
• and
• a step of, under the load operating condition, adjusting the supply amount of the pH adjuster such that pH of the feedwater in each of the at least one carbon steel component is not less than 9.8,
• wherein the pH adjuster includes ammonia,
• wherein the steam turbine plant comprises one or more steam drums for temporarily accommodating steam generated by a boiler serving as the steam generator,
• wherein the one or more steam drums include:
• a first drum supplied with the feedwater from a condenser and having a lowest internal pressure among the one or more steam drums;
• and
• a second drum supplied with the feedwater from the condenser not via the first drum and having a higher internal pressure than the first drum,
• wherein the at least one carbon steel component includes the first drum, and
• wherein the method further comprises, under the load operating condition, adjusting the supply amount of the pH adjuster such that pH of the feedwater to be supplied to the first drum is not less than 10.1.