| 摘要 |
<p>PURPOSE:To prevent the adhesion of gypsum scale to an evaporating mixer and to reduce the consumption of degassing air and steam, by a method wherein sulfuric acid added to supernatant water after gypsum separation prior to raising temp. under heating and dithionic acid is decomposed under heating by sulfuric acid without forcibly degassing SO2 from a decomposition tank. CONSTITUTION:Supernatant water 22 from a gypsum separating process is directly guided to a sulfuric acid mixer 12 and, after sulfuric acid is added in a concn. of 0.5-5% to raise the solubility of gypsum in the supernatant water, the treated water is guided to a steam mixer 11 to be heated by steam 31 to raise the temp. thereof to 95-130 deg.C and the separation of gypsum scale is prevented. Subsequently, the supernatant water 22 is guided to a decomposition tank 13 equipped with heat insulating function to decompose dithionic acid in the supernatant water. Because this process is different from a conventional one and the forcible degassing of the decomposition tank 13 using air is eliminated, it is unnecessary to blow steam 31 into the decomposition tank 13 so the steam consumption is reduced. The treated water 22' after the acid decomposing process is utilized as the replenishing water of a cooling process after it is cooled.</p> |
