Review of Mercury Formation and Capture from CO2-Enriched Oxy-Fuel Combustion Flue Gas

Oxy-fuel combustion is the ideal option among low carbon combustion technologies for post CO2 capture. Mercury in CO2-enriched flue gas must be removed efficiently because mercury can cause metal embrittlement and aluminum corrosion during post CO2 processing. To date, there is little research that has reported mercury speciation, emissions, and removal from the oxy-fuel combustion systems. Therefore, a comprehensive review of mercury chemistry and mercury removal from the oxy-fuel combustion system is necessary. This paper reviews the formation, emission, and removal of mercury from oxy-fuel combustion systems. The aim is to evaluate and summarize the fate of mercury and the status of mercury-control technologies for the oxy-fuel combustion process. It is recommended that the modification of existing ESP, SCR, or FGD systems to enhance mercury control should be developed. The investigation of mercury capture by activated carbon or other low-cost sorbents requires further research to evaluate its suitability for oxy-fuel combustion plants. The installation of additional mercury oxidation catalysts downstream of an SCR unit, where mercury would be oxidized along the economizer exit exhaust, is a promising solution. It is also recognized that the injection of a chemical oxidizing agent to control mercury emissions requires further investigation to realize the full potential of this application.