The operation data of condensate polishing system in more than 10 direct air-cooled power plants have been analysed

and a comparasion of performance indices

such as effluent quality and period of operation etc.

between the powdered resin precoated filter and the cation-anion separated bed water treatment equipment being carried out

finding out the main original source of main impurities as SiO2 and CO2 in the steam-water system

pointing out desalting ability of the powdered resin precoated filter having been basically lost.During the period of normal operation

a large amount of CO2 and dust leaks from the air into the air-cooled system

resulting in poor effluent quality of the powdered resin precoated filter

even in surpassing the set standard.The existing cation-anion bed ion-exchang systems haven't instralled prefiters for deironization

leading to the resin being contaminated by iron

making the resin to further decrease its performance

being the main cause of poor effluent quality from the said system.A scheme of optimization allocation for the condensate polishing system of the direct air-cooled units has been put forward

namely adopting prefilter + cation-anion separated bed(or mixed bed) system

i.e.the prefilter is used for removal of the metal corrosive products

and the cation-anion separated bed(or mixed bed) for removal of other impurities

such as SO2

and CO2 etc..