What is Meant by External and Internal Feed-water Treatment?
External treatment is the reduction or removal of impurities from water outside the boiler. In general, external treatment is used when the amount of one or more of the feed=water impurities is too high to be tolerated by the boiler system in question. There are many types of external treatment (softening, evaporation, deaerarion, etc.) which can be used to tailor-make feed-water for a particular system. Internal treatment is the conditioning of impurities within the boiler system. The reactions occur either in the feed-lines or in the boiler proper. Internal treatment may be used alone or in conjunction with external treatment. Its purpose is to properly react with feed-water hardness, condition slidge, scavenge oxygen and prevent boiler water foaming.
