| 摘要 |
<p>of The Disclosure The present invention is directed to a method for controlling scale which would otherwise be formed from water-soluble calcium, magnesium and iron impurities contained in boiler water which would provide calcium, magnesium and iron ions. The method comprises adding to said water: (i) a chelant selected from the group of ethylene diamine tetraacetic acid and the water soluble salts thereof, in an amount which is substoichiometric to that amount required to react with said ions present in the water; (ii) a water soluble phosphate salt which will provide phosphate ions in said water in an amount which is less than a 1:1 mole ratio of phosphate to calcium, but which is sufficient to react with all the calcium ions provided by said impurities which are not complexed by the chelant; and (iii) a water soluble polymethacrylic acid or water soluble salt thereof in an amount sufficient to disperse any particles formed by the reaction of the calcium ions with the phosphate ions and any other particulate matter formed by the reactions of the magnesium and iron ions.</p> |
