| 摘要 |
PURPOSE:To obtain chemical washing liquid capable of effectively dissolving and removing scale consisting of SiO2 as a main component by adding hydrochloric acid or sulfuric acid at specified concn. to the aq. soln. of acidic fluoride and furthermore adding polymeric phosphate and an acid etching inhibitor thereto. CONSTITUTION:Chemical washing liquid for scale of a geothermal power generation plant is obtained by adding 1-3wt.% hydrochloric acid or sulfuric acid to the aq. soln. of at least one or more kinds of acidic fluorine compd. and furthermore adding polymeric phosphate and an acid etching inhibitor. As the above-mentioned acidic fluorine compd., NH4HF2, KHF2 and NaHF2, etc., are used and suitably added at about 5-10% expressed in terms of F. Further polymeric phosphate is added at about one equivalent for Ca incorporated in scale to solubilize it. As the acid etching inhibitor, an organic amine-base inhibitor or the like is used at about 0.3-0.5%. Hard scale consisting of SiO2 as a main component is dissolved with high efficiency and also acid etching for a steel product is inhibited at a negligible degree by heating this chemical washing liquid at about 60-70 deg.C and circulating it to the plant.
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