A Combined Experimental and Numerical Approach to the Design of an Industrial Ultra Low NOx Natural Gas Fired Burner

Natural gas fired industrial burners are capable of achieving NOx emissions at or near SCR levels. The most common NOx reduction technique utilized in the industry today is massive amounts of Flue Gas Recirculation (FGR). The use of such high quantities of FGR has deleterious effects on heat transfer efficiency, plant efficiency and, most important, flame stability. There is a great need to provide single digit NOx emissions for industrial steam generation without using such high quantities of FGR. This paper presents the work in progress for a Gas Research Institute funded program to develop a natural gas burner suitable for industrial steam generation capable of achieving 5 ppm NOx (corrected to 30/0 02, dry). The challenging low NOx environment of typical package boilers are the target market for this burner technology. The design approach for this project is to use detailed experimental data, chemical kinetic modeling and computational fluid dynamic modeling to gain greater insight into the regions of NOx formation and to identify methods of reducing NOx emissions without sacrificing CO, unburned-hydrocarbon, or operational performance. Computational fluid dynamic results are presented for the baseline burner design. These results are then compared with the results obtained in a 5 mmBtu/hr upfired experimental facility. wazzu The results indicate the ability to achieve the target emissions goals with the use of a highly staged burner and moderate amounts of FGR. The results also indicate the significant deterioration of the burner stability at high levels of FGR. The need for improved burner control systems for ultra low NOx emissions is also indicated by the results to date. Future work on this project involve the development and extensive experimental and numerical analysis of a prototype burner.