Abstract: In a seawater leakage detection device in a feedwater system, a method for detecting seawater leakage in a feedwater system, and a steam turbine plant, an ammonia addition device configured to add ammonia as a pH adjusting agent to feedwater at an upstream side of a high-pressure drum in a feedwater line, an acid electrical conductivity meter configured to measure an acid electrical conductivity of drum water in the high-pressure drum, and a control device configured to control the ammonia addition device such that a pH value of 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 drum water on the basis of the acid electrical conductivity measured by the acid electrical conductivity meter, and determine whether leakage of seawater is detected are provided.

Abstract: In a seawater leakage detection device in a feedwater system, a method for detecting seawater leakage in a feedwater system, and a steam turbine plant, an ammonia addition device configured to add ammonia as a pH adjusting agent to feedwater at an upstream side of a high-pressure drum in a feedwater line, an acid electrical conductivity meter configured to measure an acid electrical conductivity of drum water in the high-pressure drum, and a control device configured to control the ammonia addition device such that a pH value of 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 drum water on the basis of the acid electrical conductivity measured by the acid electrical conductivity meter, and determine whether leakage of seawater is detected are provided.

Abstract: A chemical feed control device controls feeding of a chemical into a water system of a plant. A water quality index-obtaining unit obtains a water quality index value for each of a plurality of disruptive factors of the water system. An environmental data-obtaining unit obtains environmental data related to the plant. An operational data-obtaining unit obtains operational data related to the plant. A determination unit determines a feed amount of each of a plurality of chemicals acting on at least one disruptive factor and having components different from each other with respect to the water system based on the water quality index value, the environmental data, and the operational data such that the water quality index value for each of the disruptive factors approximates a water quality target value for each of the disruptive factors.

Abstract: In a steam plant, scale adhesion to the inside of a specific device is prevented, while reducing the amount of an agent such as hydrazine to the lowest possible level. A temporary change in the chemical environment or an approximately periodic variation in the chemical environment is brought about in a channel (21) inside the prescribed device, during operation of the steam plant.