| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technique for cleaning a hardly soluble fouling, which successfully cleans the scales of calcium salt attached to a metal surface of an apparatus, piping or the like. <P>SOLUTION: A cleaning agent for the hardly soluble fouling contains, as a component, at least formic acid, and cleans the scales of the calcium salt attached to the metal surface. A supply tank 31 for supplying the cleaning agent is connected to the centrifugal thin-film dryer 20. For example, when a waste liquid to be dried is a suspension liquid consisting mainly of calcium borate, the concentration of the formic acid in the cleaning agent is adjusted to 0.5 to 10 wt.%, preferably to 1 to 5 wt.%. <P>COPYRIGHT: (C)2013,JPO&INPIT |
