Model-based design and full-scale demonstration of an oxy-coal firing system with undiluted oxygen and minimal flue gas recycle

The future use of coal as a fuel for industrial applications depends on economical technologies being made available to capture and store the CO2 emitted as a product of the combustion process. One such technology is oxy-combustion, which involves burning of the fuel using pure oxygen as the oxidant rather than air. Since heat from combustion does not go toward the heating of nitrogen in the air, flame temperatures with oxy-combustion increase dramatically. First-generation application of the oxy-combustion depends on flue gas recycle (FGR) introduced in or around the burners to modulate flame temperatures to make the technology a retrofit option for existing power generating units. A second generation oxy-combustion technology that uses minimal FGR produces high-temperature flames in excess of 4000°F. Application of this technology shows promise for enabling capture, utilization, and sequestration of CO2. However, a major step in the advancement of the technology and use in retrofit applications is the development of a burner design strategy capable of producing and sustaining the high-temperature conditions from oxy-firing of coal while providing protection to burner internals and near-burner surfaces from the high heat fluxes produced. This paper discusses the development of a patented high-temperature oxy-coal firing system that has been constructed and tested in a full-scale demonstration. The patented design was achieved through Reaction Engineering International's commercial and government R&D programs involving CFD modeling coupled with multi-scale experiments. CFD model predictions corroborated by experimental data evaluated impacts of oxy-coal burner design on flame behavior, heat release and heat flux. The best performing designs were then modeled at an industrial-sized scale in a single burner test facility as well as in wall-fired and tangentially-fired utility-scale boilers. The paper describes the results of burner performance simulations that guided the evolution of high-temperature oxy-coal burner concepts to a design patented by Jupiter Oxygen Corporation (JOC). Full-scale testing of the JOC patented design will be performed with a single 60 MMBtu/hr burner to evaluate performance over a range of conditions including air firing. Performance metrics such as flame location/stability, local peak tube/burner temperatures and heat fluxes, carbon conversion, and NOx emissions will be discussed along with comparisons to CFD model simulations of the demonstration's test conditions.