Online trace analysis of amines in the alkaline water-steam circuit of power plants

Importance of the topic

Maintaining slightly alkaline conditions in water-steam cycles is essential to prevent corrosion and protect boiler, turbine, and condenser metals. Continuous monitoring of volatile amines ensures precise pH control and system integrity.

Aims and Study Overview

This application note presents an automated inline ion chromatography method to detect trace amines and cations in alkaline water-steam circuits of thermal power plants. It focuses on enabling real-time process control to reduce maintenance downtime and corrosion risks.

Methodology and Instrumentation

The method employs a Metrohm 2060 IC Process Analyzer equipped with:

• Modular wet part and eluent production modules
• MiPT (intelligent Partial Loop Technique) for precise sample handling
• Conductivity detection with sequential cation suppression
• Integrated column oven (up to 40 °C) for enhanced stability

Samples are drawn continuously via bypass, calibrated automatically, and measured for cations (e.g. Na⁺, NH₄⁺, Ca²⁺, Mg²⁺) and amines (e.g. ethanolamine, morpholine, DMA, 3-methoxypropylamine).

Main Results and Discussion

The system achieved low ng/L detection limits, high reproducibility, and recovery rates. A representative chromatogram demonstrated simultaneous quantification of multiple ions at 1 mg/L levels. Baseline noise was minimized by cation suppression, ensuring reliable trace analysis under process conditions.

Benefits and Practical Applications

• Inline eluent preparation for stable baselines
• Automated sampling and calibration for safe, unattended operation
• High-precision detection across a wide dynamic range
• Protection of critical plant assets by early corrosion detection

Future Trends and Potential Applications

Advancements may include AI-driven data analytics, expanded ion panels for contaminant profiling, miniaturized flow cells for decentralized monitoring, and integration with digital plant management systems for predictive maintenance.

Conclusion

Automated ion chromatography using the 2060 IC Process Analyzer offers a robust, sensitive solution for online monitoring of amines and cations in power plant water-steam circuits, supporting reliable corrosion control and operational efficiency.

Reference

• AN-C-049 Trace cations in power plant feed water stabilized with 7 ppm monoethanolamine (MEA)
• AN-CS-010 Traces of lithium and sodium besides monoethanolamine in water-steam circuits of thermal power plants
• AN-C-139 Cations and amines in the water-steam cycle