Dawukou Power Plant used Dimethyl ketoxime as the deoxidizing agent（DMKO） on four of its HP 410 t/h boilers.It was indicated by two years industrial tests that though it had some deoxidizing effect

but negative result came up with its application

such as grow-up of scaliing

yellow color of turbine blade

degradation of feedwater in C u content

etc.It showed no advantages over N 2H 4 that were commonly used in the fossil-fired power plant.After stopping use of DMKO agent for half a year（from January to June

1998）

the steam and water qualities were improved significantly

especially the contents of Cu and Fe（100%）.No red color was found in the sampling water any more.