Insitu Study of the Effects of Anthraquinone, White Liquor Concentration and Temperature on Lower Zone Digester Corrosion

摘要

The present insitu work studied the effects of anthraquinone (AQ), white liquor concentration and temperature on corrosion rate of a Kamyr continuous digester. The effects of adding white liquor into the wash zone of the digester was studied on a real time basis. The techniques used were polarization curves, electrochemical potential measurements and monitoring coupons. Ultrasonic testing results confirmed that corrosion of the digester was mitigated as long as the electrochemical potential was kept at the passive zone. AQ did not have any direct influence on the corrosion rate of the continuous digester. Corrosion of this digester could be mitigated by the addition of white liquor from the cooking nozzles. Field measurements indicated when there was a potential excursion into the active corrosion zone, the potential may be moved back into the passive zone by additional liquor injection. Anodic protection is compatible with the use of AQ for corrosion and cracking protection in conventional, MCC~R and LoSolids~(TM) digesters.