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Posted by Rick on June 20, 2004 at 09:18:25:
In Reply to: Sulfite Levels in DA Tanks posted by John on June 19, 2004 at 09:32:51:
: Is there a way, or does it make sense to monitor the sulfite levels in the DA tank?
: For years we have monitored the sulfite levels in the boiler at the recommendations of our chemical suppliers. We have suffered some pitting in the DA tank over the last 10 years. Presently we have turned our oxygen scavenger chemical pump down to a trickle and are still maintaining the proper sulfite level. This is causing some concern for the well being of the DA tank.
Pitting in the DA is caused by improper deaeration. The problem could be from faulty spray valves, bent, warped or partially plugged distribution trays or holes or cracks in the waterbox section that holds the trays. If your feedwater temperature in the storage section compares +/- 3 degrees with the temperature of the supply steam, the spray valves and trays are probably okay. You still could have problems with the waterbox that would cause short-circuiting of the water and improper deaeration.