Ultra-low NOx burner arrangements in furnace revamps: utilization of CFD to prevent and mitigate adverse furnace flow patterns

As NOx emission regulations continue to become more stringent, the need to retrofit existing furnaces with Ultra-low NOx burner technology will continue to rise. Ultra-low NOx emissions from process burners are typically achieved by combining staged combustion with internal flue gas recirculation. As a result, the flames from an Ultra-low NOx burner are longer and exhibit lower peak flame temperatures compared to the flames from a conventional type of burner. These characteristics make the performance of Ultra-low NOx burners more susceptible to furnace flow patterns than conventional burners. In order to mitigate the effects of adverse furnace flow patterns, tools such as Computational Fluid Dynamics (CFD) can be used to reveal the flue gas flow patterns inside of a particular furnace. This knowledge can then be used to optimize the burner design. The John Zink Company frequently uses CFD in this fashion and several successful case studies are presented.