Seawater leakage detection device in feedwater system, method for detecting seawater leakage in feedwater system, and steam turbine plant

A seawater leakage detection device in a feedwater system in a steam turbine plant including a heat recovery steam generator including a steam drum configured to produce steam using exhaust heat of exhaust gas, a steam turbine configured to be driven by the steam produced by the heat recovery steam generator, and a condenser configured to return feedwater produced by cooling steam discharged from the steam turbine with seawater to the heat recovery steam generator, comprising:

• a pH adjusting agent addition device configured to add a pH adjusting agent to feedwater at an upstream side of the steam drum in a feedwater line;
• an acid electrical conductivity meter configured to measure an acid electrical conductivity of drum water in the steam drum;
• and
• a control device configured to control the pH adjusting agent addition device such that a pH value of the drum water in the heat recovery steam generator expresses alkalinity equal to or greater than a preset predetermined value, calculate a chlorine ion concentration of the drum water on the basis of the acid electrical conductivity measured by the acid electrical conductivity meter while the pH value of the drum water is maintained equal to or greater than the predetermined value, and determine whether seawater leakage is detected.