Ammonia in cooling water of thermal power plants

Importance of the Topic

Thermal power plants use high-purity steam cycles to produce electricity. Maintaining optimal condenser performance in their cooling water circuits is critical to plant efficiency and reliability. Ammonia contamination in the cooling water can promote copper alloy corrosion and biological fouling, which risks equipment damage, unscheduled shutdowns and environmental discharge concerns.

Objectives and Overview

This application note describes an approach for continuous online monitoring of ammonia in recirculating cooling water systems. It aims to detect early rises in NH3 concentration to trigger timely chemical dosing and prevent copper corrosion in condensers. The study reviews instrumentation options and measurement protocols suited to industrial power plant environments.

Methodology and Instrumentation Used

Ammonia analysis is performed with Metrohm Process Analytics equipment:

• 2060 Process Analyzer: a modular wet chemistry platform supporting titration, photometry and standard addition techniques.
• 2026 Titrolyzer: a high-precision potentiometric titrator enabling dynamic standard addition with ion-selective electrodes.

Samples are combined online with a Total Ionic Strength Adjustment Buffer (TISAB) to raise pH above 11. An ammonia ion-selective electrode (NH3-ISE) measures NH3 via dynamic standard addition to account for electrode slope and matrix effects.

Main Results and Discussion

Continuous monitoring over periods up to 130 days reveals transient spikes in NH3 concentration that, if left unchecked, would accelerate copper corrosion and fouling. Control limits (e.g. 2 mg/L NH3) can be configured in the analyzer software to issue alarms and enable prompt dosing of corrosion inhibitors or chlorine. The approach provides reliable, low-maintenance operation suitable for harsh cooling water matrices.

Benefits and Practical Applications

The online ammonia measurement strategy delivers:

• Reduced unplanned downtime through early-warning alarms.
• Protection of copper alloy condensers and associated piping.
• Optimized chemical usage by dosing only when NH3 levels exceed thresholds.
• Environmental compliance by minimizing copper release in blowdown streams.

Future Trends and Potential Applications

Advances in sensor technology and data analytics will enhance the sensitivity and predictive power of ammonia monitoring systems. Integration with plant control systems and use of machine learning could optimize chemical dosing schedules. Similar online analyzers can be extended to track silica, sodium, iron, copper and other critical parameters in power plant cycles and emissions control.

Conclusion

Implementing continuous online ammonia determination in cooling water circuits is a proactive measure to safeguard thermal power plant assets. Utilizing Metrohm Process Analytics’ modular analyzers and ISE-based dynamic standard addition ensures accurate, real-time data for corrosion prevention and process optimization.

References

1. Metrohm Application Note AN-PAN-1040: Ammonia in cooling water of thermal power plants
2. Electric Power Research Institute (EPRI) guidelines on copper alloy corrosion control in power plant condensers