Abstract: There is provided an improvement in the method of regenerating the anion portion of a mixed anion/cation exchange resin bed used for purification of condensate water. The improvement comprises utilizing a clear dilute lime solution substantially free of non-hydroxylic anions. This solution is produced by passing a solution of calcium salt through a strong base anion exchanger in the hydroxyl form, and thus producing calcium hydroxide by salt splitting. The spent resin is regenerated with spent caustic regenerant from a condensate purification process or with fresh caustic. It is preferred that the calcium solution and the regenerant enter the ion exchanger in counterflow pattern to minimize leakage of non-hydroxy ions.

Abstract: An ion exchange system having a number of vessels containing beds of ion exchange material that remain in the same vessel during exhaustion and regeneration is operated so that the efficiency of exhaustion and regeneration is increased and the amount of time the vessels and ion exchange material stand idle is reduced. A number of vessels are connected in parallel in service while other vessels are connected in series for regeneration. Vessels with freshly regenerated ion exchange material are connected in series with the service vessel containing the most nearly exhausted bed of ion exchange material while that bed is being substantially completely exhausted.