Amir,
Sorry for the confusion. The ACC inlet header, not heater… I mean the point at which the steam enters the ACC tube bundles.
Sounds like your steam pH is kept in a good range. We also operate AVT with ammonia only, and have found keeping the steam pH above 9.8 minimizes the 2 pt FAC in the STG exhaust duct and ACC inlet duct.
We also had the same issue that Chris Karch discussed with the hogger isolation valve.
Good luck sir,
Chris
