| 摘要 |
PURPOSE:To prevent the corrosion of an iron-base metal in the water system of a boiler using soft water at a high temp. by adding a specified phosphorus compd., a specified carboxylic acid compd. and a specified metallic compd. each at a specified concn. to the water system. CONSTITUTION:Disoxidation is carried out in the water system of a boiler using soft water at a high temp. of 150-250 deg.C by adding 10-200mg/l phosphorus compd. (a) selected among polyphosphoric acids such as nitrilotrimethylphosphonic acid, orthophosphoric acids such as 1,1- hydroxyethanediphosphonic acid and org. phosphoric acids such as bis-poly-2- carboxyethylphosphinic acid, 40-500mg/l carboxylic acid (b) selected among aliphatic oxycarboxylic acids such as citric acid and amino acids such as nitrilotriacetic acid and 0.5-50mg/l metallic compd. (c) readily releasing ions of a metal selected among Sn, Zn, Mn and Ni in water, e.g., sulfate. The weight ratio of the compd. (b) to metal ions released from the compd. (c) is regulated to >=3.
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