Characterization and Prediction of Oxy-combustion Impacts in Existing Coal-fired Boilers

Future use of coal for power generation in the US depends on technologies being made available to capture and store CO2 emissions from power plants. A key candidate CO2 capture technology is oxy-firing of coal. Application of oxy-firing to existing power plants presents unquantified challenges as the characteristics of oxy-firing compared to airfiring have not been fully determined. This presentation will review the status of an on-going DOE-funded program to characterize and predict impacts of CO2 flue gas recycle and burner feed design on flame characteristics (burnout, emissions and heat transfer), fouling, slagging, and corrosion, inherent in the retrofit of existing coal-fired boilers for oxy-coal combustion. Key deliverables from the project include: • Multi-scale test data from 0.1 kW bench-scale, 100 kW laboratory-scale and 1.2 MW semi-industrial scale combustors that describe differences in flame characteristics, fouling, slagging and corrosion for coal combustion under air-firing and oxygen-firing conditions, including sensitivity to oxy-burner design and flue gas recycle composition. • Validated mechanisms developed from multi-scale test data that describe fouling, slagging, waterwall corrosion, heat transfer, char burnout and sooting under coal oxy-combustion conditions. • Principles to guide design of pilot-scale and full-scale coal oxy-firing systems and flue gas recycle configurations, such that boiler operational impacts from oxycombustion retrofits are minimized. • Assessment of oxy-combustion retrofit impacts in a full-scale coal-fired utility boiler using computational fluid dynamics (CFD) modeling of air-fired and oxygen-fired operation, together with the information generated in this research. The experimental data, oxy-firing system principles and oxy-combustion process mechanisms provided by this work can be used by electric utilities, boiler OEMs, equipment suppliers, design firms, software vendors, consultants and government agencies to assess retrofit applications of oxy-combustion technologies to existing boilers or to guide development of new designs.