| 摘要 |
<p>PROBLEM TO BE SOLVED: To surely prevent the adhesion of scale without needing pretreatment by a method in which when drainage from a power station is evaporated and concentrated, the pH of the drainage is adjusted between a weak acid area and a neutral area and added with a water soluble polymer such as acrylic acid type polymer or copolymer, and the mixture is evaporated and concentrated. SOLUTION: Flue gas desulfurizartion drainage is stored in a pH adjustment tank 1 from a drainage supply line (aa), and the pH of the drainage is adjusted between a weak acid area and a neutral area by injecting a sodium hydroxide aqueous solution. Next, the drainage is supplied to an evaporation-concentration apparatus 2 by a drainage supply pump 9, the pressure is reduced by a vacuum pump 12, and the drainage is brought into a heated state. A water soluble polymer selected from acrylic acid type polymer or copolymer, maleic acid type polymer or copolymer, and sulfonic acid type polymer or copolymer is added from storage tanks 6, 7. While steam generated in the evaporation- concentration apparatus 2 being discharged outside the system by a condensed water pump 13, the obtained concentrated liquid is discharged to a concentration tank 4 through a concentrated liquid circulating pump 10.</p> |
