The operation of condensate polishing system in a supercritical 1 000 MW unit was diagnosed

by the professional diagnosing system for high-speed mixed beds designed by Xi'an Thermal Power Research Institute.Thus the existing problems occurred in high speed mixed bed and separation-regeneration equipment were found out.After operation optimization like parameter regulation was carried out

the periodic output amount of fabricated water from mixed bed increased from 70 000m3 to 130 000m3.The percent of cation resins in anion resins decreased from 1.2%to 0.1%

and the percent of anion resins in cation resins decreased from 0.54% to 0.08%.The water quality of mixed bed effluent meets expectations related in GB/T12145—2008.For long-time operation after optimization

the technical quality index of water and steam was significantly improved.