| 摘要 |
PROBLEM TO BE SOLVED: To retain a concentration of urea water in a tank to a constant value by suppressing evaporation of moisture content of urea water. SOLUTION: In the storage method for urea water 17 to be added as a reducing agent to a selective reduction type catalyst 10 for reducing/cleaning NOx, hardly volatile fats and oils 18 having property that it is separated without being mixed with urea water 17 and smaller specific gravity than urea water 17 are stored with urea water 17 together and a film of fats and oils 18 is laid on urea water 17 by difference of specific gravity to cover a liquid surface of urea water 17. Thereby, evaporation of moisture content of urea water 17 is suppressed to retain a concentration of urea water 17 in the urea water tank 14 to a constant value. COPYRIGHT: (C)2006,JPO&NCIPI
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