Condensate Polishers

Another variation of the standard demineralizer system is the condensate polisher. Many high-pressure boiler systems incorporate a vessel loaded with strong acid cation resin or a combination of cation and anion resin to polish the steam condensate coming from turbogenerator surface condensers. Because many of these systems return a high percentage of their steam condensate as boiler feed water makeup, the polishers serve to insure that any contaminants that might enter the condensate (as from the condenser leaks) are removed prior to reuse.

In the past, condensate polishers loaded only with strong acid cation resin were regenerated with salt. Because the sodium emanating from these units during the exchange process is detrimental to the control of high pressure boiler water treatment programs, morpholine or ammonia has been substituted in many cases. Before either of these amines are used for regeneration, the polisher resin must first be put in the hydrogen form by regeneration with sulfuric acid. Next, the polisher is regenerated with the amine, which readily exchanges for the hydrogen. During normal operation, the morpholine or ammonia exchanges for the more objectionable cations (Ca⁺⁺, Mg⁺⁺, etc.). Regeneration and operation of a mixed-bed polisher is identical to that of a standard demineralizer polisher. The only drawback to the operation of a mixed-bed polisher is that it removes any neutralizing amine fed to the boiler system and therefore loses considerable capacity even though no other contaminant exists.