Development for Novel Identification Method of Seawater Contamination into Steam-Water Circuit Including Carbon Dioxide of Power Plants Based on Chemical Equilibrium Calculation
In the steam-water circuit of thermal power plants, cation conductivity is measured to detect at an early stage the leakage of seawater into the condenser. However, there is the problem of carbon dioxide interfering with the measurement. To address this issue, a novel model for identifying seawater leakage has been devised. It is a model based on chemical equilibrium calculation considering not only cation conductivity but also pH and electrical conductivity. This novel identification model was verified using chemical equilibrium calculation software and water quality data from the actual unit. The results show good accuracy with an error of 0 to 20 % with chemical equilibrium calculation software. It has also been confirmed that trace seawater leaks can be detected before reaching the reference value prescribed by JIS B 8223 for feedwater control (i.e., cation conductivity of 0.5 μS/cm), which makes it possible to detect seawater leakage promptly and easily even in the presence of carbon dioxide.
