Achieving and Maintaining Hg Oxidation Performance through SCR Catalyst Selection and Management

摘要

The co-benefit of oxidized Hg capture by desulfurization systems is an effective and economical method to achieve compliance with Utility MACT limits. As is the case for maintaining required DeNO_x emission requirements, catalyst additions and replacements (actions) will be managed to achieve and maintain Hg oxidation levels. For DeNO_x, catalyst samples are tested annually to determine DeNO_x activity, deactivation rate and cause. Data is then used in combination with plant specific considerations to determine the appropriate catalyst action(s) to maintain SCR system performance. Fresh and used catalyst Hg oxidation test results and modeling indicate such annual testing may be used analogously to manage SCR Hg oxidation performance. Also, under more challenging conditions such as low chlorine in flue gas, catalyst actions may include our advanced catalysts which have been designed to significantly improve Hg oxidation. Information including performance and durability testing results are reviewed along with catalyst management case studies.