Abstract
The Electric Power Research Institute (EPRI) and Det Norske Veritas USA, Inc. (DNV) performed a field-testing program that supported the “Corrosion in Wet Flue Gas Desulfurization Systems” study. This study was motivated by the fact that many alloy wet flue gas desulfurization (WFGD) absorbers of recent construction are experiencing premature failure from localized corrosion. The alloys of construction most affected by localized corrosion attack are: (1) UNS S32205 – a duplex stainless steel and (2) UNS S31703 – an austenitic stainless steel. The rate of attack on these alloys has exceeded 12 millimeters per year (500 mils per year) in forced oxidation WFGD service. A corrosion rate of this magnitude can lead to perforation of the absorber walls and floor in less than one year of service. The time to initiate localized attack can be as little as two to three months. Compounding the issue, UNS S32205 and UNS S31703 have seen the highest use rate for the fabrication of new WFGD absorbers.
The combination of high corrosion rates and widespread use of these alloys has created industry-wide concern for unit availability and unexpected changes in the life cycle cost of emissions control equipment. The field-testing was a product of the findings of a technical root cause analysis (TRCA) conducted in 2011 by DNV on behalf of the Electric Power Research Institute (EPRI).
