Regenerating mixed ion exchange resins for water desalination - by backwashing then removing middle layer of mixed resin

摘要

Method for regenerating mixed anionic and cationic exchange resin comprises backwashing with water to separate the resin into upper, middle and lower layers. The upper and lower layers are regenerated separately then remixed. The middle layer of mixed resin is withdrawn and added to the resin mixt. during the next regeneration process at same stage before backwashing. Either the upper or lower layer is also removed for regeneration and pref. fine particles are removed from the middle layer. Used for water desalination e.g. in thermal or nuclear power station boiler systems. Since only pure resin layers are regenerated loss of regeneration efficiency and ion-exchange capacity are prevented. Water quality is thus improved esp. the amt. of impurities such as Na+ introduced from any cation exchanger mixed with the anion exchange during regeneration with NaOH.