Mitsubishi Heavy Industries Technical Review
    Vol. 52 No. 2 (2015)   Mitsubishi Hitachi Power Systems
    Technical Papers

    Advantages and New Technologies of High-AVT Water Treatment in Combined Cycle Plants

    Senichi Tsubakizaki,
    Akito Yoshida,
    Kouichi Tagami,
    Shunichi Sato,
    Mitsuru Nakamoto,
    Kouki Ohkubo

    In today's water treatment using the heat recovery steam generator (HRSG) of combined cycle plants, ammonia and hydrazine are used in the feedwater system and sodium phosphate is used in the boiler system. In recent years, however, corrosion due to phosphate has occurred at some plants, and efforts to realize hydrazine-free water treatment will be needed in the future. To cope with these issues, conversion to high-AVT water treatment is effective, and its actual performance has been well-received and was adopted as the JIS standards revision proposal. Mitsubishi Hitachi Power Systems, Ltd. (MHPS) developed the new technologies for conversion to high-AVT water treatment, specifically neutral room-temperature chemical cleaning and an electrolytic denitrification system for high-pH waste water, which will be introduced below.