Study Results of Combustion Characteristics in Oxy-Fuel Combustion Process

Oxy-fuel combustion is expected to be one of the promising systems on CO2 capture from pulverized-coal fired power plant, and enable the CO2 to be captured in a more cost-effective manner compared to other CO2 capture process with the power generation from the results of previous study. Some studies in this area are implemented under Australia-Japan consortium established in 2004 and joint venture for Callide Oxy-fuel Project under Australia-Japan consortium is established in March 2008. The project is now under way for the retrofit oxy-fuel combustion to an existing power plant by way of demonstration and is implemented in Callide-A power plant No.4 unit owned by CS Energy with a capacity of 30MWe in Australia. This project aims at capturing CO2 from an actual power plant for CO2 storage. The demonstration operation will start in 2011. One of the key issues to achieve the reliable and stable operation is countermeasure against corrosion. Recently, we studied the behaviors of corrosive substances in combustion gas and trace elements in flue gas, which is mainly sulfur compounds and Hg respectively. Sulfur compounds causes corrosion of boiler tubes, and Hg causes corrosion of aluminum base heat exchangers in the CO2 processing unit. Knowledge of their behaviors in oxyfuel is insufficient, and obtaining their knowledge is important for suitable material selection, countermeasure against corrosion, and optimal process design. In order to confirm the behaviors of corrosion components and Hg, the pilot-scale combustion test in IHI is performed at the combustion test facilities; the capacity of the furnace is 1.2MWt. The combustion test is conducted under oxy-fuel and air combustion conditions because of confirmation of the difference in both conditions. In this paper, the behaviors of corrosion components and Hg in the oxy-fuel combustion process are introduced. These results obtained in this study can significantly contribute to the design and the improvement of the oxyfuel combustion process towards the commercialization.