GB299074A - Process for conditioning or treating water in boilers and the like to prevent incrustation and corrosion - Google Patents

Abstract

299,074. Gordon, J. May 17, 1927. Incrustation and corrosion, preventing.-Incrustation in boilers is prevented by adding to the boiler water a soluble phosphate to precipitate calcium phosphate, and maintaining the concentration of phosphate by further additions during evaporation, to ensure the precipitation of calcium as phosphate sludge rather than as adherent sulphate scale. A fluoride or arsenate may be used in place of phosphate. It is preferred to remove most of the calcium and magnesium by a preliminary treatment with lime and soda ash, or by a base exchange process, and the precipitates are separated from the feed water. Curves are prepared, showing the concentration of phosphate radical relatively to the sulphate radical at different boiler pressures, which 'it is necessary to maintain in the boiler to ensure the precipitation of calcum as phosphate. The hydroxyl concentration produced by hydrolysis of the soluble phosphate may be minimized, to prevent precipitation of magnesium as silicate or hydroxide, by the use of disodium hydrogen phosphate, or phosphoric acid. A preliminary treatment with a barium salt to remove sulphate as barium sulphate may be employed. The process is suitable for use in boilers operating at high temperatures and pressures.