New Corrosion Inhibition Approach under High Corrosive Condition in Cooling Water Systems

Abstract Make up water for cooling water systems is diversifying because water shortage becomes serious issue in many countries. Recently RO treated water and process condensate have started to be used as make up water. Calcium hardness in make up water forms corrosion protection film on metal surface in cooling water. But RO treated water and process condensate are contained few calcium hardness. Therefore they show high corrosivity in comparison with normal fresh water. Phosphate and zinc have been generally used for corrosion inhibitor of heat exchanger tubes and piping in cooling water systems. Under high corrosive condition, it is necessary to increase these components concentration for improvement of corrosion inhibition effect. But discharge regulations of plants are becoming severe to reduce environmental impact. Corrosion inhibition program is required to reduce phosphate and zinc concentration under high corrosive condition. To solve the problems mentioned above, the functions of low molecular weight polymer were focused on. Low molecular weight polymer is normally used for cooling water systems to prevent scaling. New polymer which can form corrosion protection film on rusting area rapidly was developed. Corrosion and scale inhibitor which was blended new polymer showed superior corrosion inhibition effect than conventional inhibitors. Furthermore this polymer can decrease phosphate and zinc concentration under high corrosive condition in cooling water systems.