Combustion Efficiency and CO2 Emission from O2/N2, O2/CO2, and O2/RFG Coal Combustion Processes

Abstract

This study investigated the combustion efficiencies and emission characteristics of oxygen/recycled flue gas (O2/RFG) coal combustion processes. The effects of different operating conditions such as the feed gas compositions and concentrations, and the ratios of RFG were also discussed. Experimental results showed that the average concentration of CO2 produced in O2/CO2 combustion was higher than 92%, while the maximum concentration of CO2 was near 34% in O2/N2 combustion. This high concentration of CO2 in the flue gas of O2/CO2 combustion is beneficial for the control, separation, and recovery of CO2 during the combustion of fossil fuel. Upon increasing the O2 concentration in the feed gas of O2/RFG coal combustion, the formation of CO was decreased and the combustion efficiency was increased. Introducing the RFG into the second combustion chamber had higher combustion efficiency than that into the first combustion chamber. The mass flow rates of CO2, CO, and O2 were all increased with the ratios of RFG except for a few cases. With suitable gas compositions O2/CO2 and sufficient O2 concentration in the feed gas, high combustion efficiency and recovery efficiency of air pollutants could be achieved.