External Regeneration:

A few mixed-bed demineralizers are designed to be reproduced externally, along with the resins being erased from the vessel, reproduced, and then exchange. With this category of demineralizer, the first step is to sluice the mixed bed along with water (sometimes assisted through air pressure) to a cation tank within a reproduced facility. The resins are backwashed within this tank to erase suspended solids and to divide the resins. The anion resins are then sluiced to an anion tank. The two batches of separated resins are reproduced through the similar techniques used for single-bed ion exchangers. They are then sluiced into a holding tank where air is used to remix them. The mixed, reproduced, resins are then sluiced back to the demineralizer.

External regeneration is classically used for groups of condensate demineralizers. Having one middle regeneration facility decreases the complexity and cost of installing various demineralizers.

External regeneration also permits keeping a spare bed of resins in a containing tank. Then, while a demineralizer required to be reproduced, it is out of service just for the time needed to sluice out the depleted bed and sluice a fresh bed in from the containing tank. A central regeneration facility may also include an ultrasonic cleaner that could erase the strongly adherent coating of dirt or iron oxide that frequently forms on resin beads. This ultrasonic cleaning reduces the need for chemical reproducing.