Test & measurement S


team and water quality analysis performs a critical role in the protection of power plants from corrosion and deposition in the water steam cycle. This is because very small changes in water and steam quality have the potential to impact the performance of the entire power station and cause hugely expensive outages. The cost of monitoring equipment is therefore negligible in comparison with the potential costs of failure to manage water and steam quality effectively, so power plant chemists are constantly seeking accuracy and reliability in their instrumentation. “Our main driver is to always ensure good feedwater quality, free from corrosive species,” explains power station chemist Adrian Bailey from VPI. “To achieve that goal, we need instruments that can deliver the highest performance levels continuously 24/7, 365 days of the year. For that reason, having tried most of the monitors on the market, we have gradually migrated almost all the water quality monitors at our five UK locations to Swan Analytical instruments.”


In addition to risk reduction, water quality monitoring also enhances process efficiency, protects plant longevity and availability, and helps ensure compliance with environmental permits.


BACKGROUND Various forms of corrosion can affect the metallic surfaces within the internal components of power plants. Corrosion is an electrochemical process, and any build-up of dissolved contaminants such as chlorides, sulphates or other detrimental species could strongly enhance the risk of corrosion such as pitting, flow accelerated corrosion and stress corrosion cracking. This risk is amplified where high temperatures accelerate the corrosion process. Low pH-values in combination with turbulent flow conditions can cause flow-accelerated corrosion (FAC), which is known to be very fast, destructive, and continues to be one of the main root causes of boiler tube failures. Power plant water steam cycle


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January 2024 Instrumentation Monthly


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