Technical Review: Laboratory Testing and Boiler Trials Fail to Produce Evidence that Studs Mitigate Corrosion of Recovery Boiler Tubes.

摘要

Standard descriptions of mechanisms and claims of effectiveness in mitigating corrosion of recovery boiler tubes by applying metal studs to the tubes require careful scrutiny, especially in the absence of systematic evidence that shows studs effectively mitigate corrosion. To the contrary, fundamental research on recovery boiler corrosion mechanisms - namely the 12-year, multi-million dollar, AF&PA/DOE research program at FP Innovations PAPRICAN and IPST investigating recovery boiler tube corrosion mechanisms - presents basic reasons why studs cannot mitigate tube corrosion and may increase tube corrosion. Additional support comes from extensive field testing and experience — namely in eight recovery boilers with studded carbon steel tubes in mills previously operated by Champion International, where the author was employed until 2001. This paper describes empirical and laboratory results that contradict the concept that studs inhibit corrosion of recovery boiler tubes by retaining a smelt layer on the tube surface that reduces the tube temperature and prevents sulfur gases from reaching the tube. It also proposes a simple and safe method for testing the efficacy of studs in any recovery boiler, as the basis for cost-benefit analysis of continued studding, which costs the industry millions of dollars a year.^