Posted by Tony Conner on October 10, 2001 at 11:52:25:
In Reply to: co2 in BFW posted by vinay alvares on October 10, 2001 at 09:46:19:
Alkalinity in make-up water breaks down into CO2 under boiler conditions, and gets carried out with the steam. It dissolves in the condensate, and makes it acidic.
You need a dealkalizer to handle the alkalinity - they're similar in appearance to softeners, and are usually installed just before or after the softeners, depending upon water conditions. The DA only handles dissolved gases. The closer the water gets to the boiling point (at whatever the pressure is), the lower the amount of dissolved oxygen it can hold. Run tests for sulphite residual in the DA storage section, and the boilers themselves. If the feedpumps have been improperly selected/installed, you can get air being sucked in around the seals/packing. This oxygen is introduced after the DA, so it eats up the sulphite, and can cause pitting of the feedwater lines, and/or boiler.