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Posted by Vern on June 19, 2004 at 19:32:30:
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.
Yes, I think it is a good idea.Simply sample the feedwater for SO3. The theoretical concentration should be desired boiler residual divided by cycles of concentration. Example: Desired boiler residual is 45ppm SO3 and cycles are 5. PPM SO3 in feedwater would be 9 ppm. All feed water tanks such as D/A's are susceptible to pitting corrosion. But it is up to the customer to decide if there is any extra chemical cost and if it is worth it to the customer.