METHOD FOR CORROSION INHIBITION OF METAL IN OPEN TYPE CIRCULATING COOLING WATER SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an excellent method for corrosion inhibition of metal in an open type circulating cooling water system of a high silica concentration without containing environmental pollutants, such as heavy metals and phospho rus, and without forming scale in the water system by increasing the thickening degree of a cooling water column.;SOLUTION: The method of suppressing the corrosion of the metal in the open type circulating cooling water system comprises increasing the thickening degree of the cooling water column and adding a water-soluble maleic acid copolymer composed as (A) 70 to 90 wt.% (in terms of maleic anhydride) ≥1 kind of maleic anhydride, maleic acid and their water-soluble salts and (B) 10 to 30 wt.% nonionic monoethylenically unsaturated monomer into circulating water prepared in such a manner that the silica concentration is 70 to 300 (mg/l) and that a correction Ryznar index; RI' including a correction term of a silica concentration expressed by formula: RI'=RI-0.004×[SiO2] (mg/l) (where RI is a Ryznar index at 40°C and [SiO2] (mg/l) is the silica concentration in the circulating water) attains 3.0 to 6.0.;COPYRIGHT: (C)2003,JPO