| Think of a steam boiler as a large teakettle on the
boil. A steam heating system is steam piped to areas where it heats something, cools,
condenses to liquid water and returns to the boiler. Protecting a closed steam heating system requires
controlling the chemistries
of three waters.
make-up water
This is tap water which enters the system
automatically to “make-up” for any water losses anywhere in the
system (boiler water, steam or condensate). A tight system with little
make-up is ideal because “raw” water contains dissolved gases and
minerals which lead to corrosion and scaling.
Under high make-up conditions, a softener is the most
economical boiler scale preventive. Soft water does not form scale because the scale-forming calcium (Ca++) and magnesium (Mg++)
ions are removed. They remain in the softener until they are flushed
down the drain when the ion-exchange resin is regenerated with brine.
boiler water
This is boiling water in the guts of the boiler. It is contributed to by
feed water - a combination of make-up water and condensed steam
(condensate). Chemicals
used to prevent corrosion, scale and carry-over are added to the boiler’s
feed-water or directly to the boiler.
condensate
If steam bubbles
break at the boiling surface, chemically-rich boiler water stays in
the boiler. Pure steam and condensate result. If bubbles don't break
cleanly, boiler water carries over with steam. Contaminated
steam causes problems everywhere it goes - in steam lines, heat
exchangers, humidifiers, steam traps and condensate return lines.
preventing foaming
preventing rusting corrosion
preventing steam and condensate
line corrosion
|