ENV-06-155 Optimizing the Performance of Ultra-Low-Emission Burners in Refinery and Chemical Plant Furnaces

Description:

To satisfy tightening environmental regulations, a new generation of ultra-low-emission burners is being retrofitted to many refinery and chemical plant furnaces. These burners are capable of producing significantly lower NOx emissions than prior models. However, to obtain optimum performance, careful integration of these burners into a heater’s radiant section is critical. If sufficient care is not taken during the retrofit design process, flame impingement on the process tubes may occur. Such impingement will elevate local tube heat flux levels, resulting in decreased run lengths between decoking operations, shortened tube life and, potentially, tube failures. In addition, the NOx emissions produced by these burners can be significantly influenced by the furnace configuration. Overlooking this impact can lead to emission levels that fall short of expectations. Computational fluid dynamics (CFD) modeling has proven to be an effective tool in optimizing burner layouts and thereby avoiding furnace performance issues. Consequently, CFD modeling is now being fully integrated into the retrofit design process by major oil companies. These models are able to predict flame shape, heat transfer rates, and tube metal temperatures for proposed retrofit configurations. The likely impact of burner layout on NOx emissions can also be assessed. In this paper, the CFD modeling approach for refinery and chemical plant furnaces is described. Practical benefits are illustrated by discussing CFD’s role in the development of ultra-lowemission burners and in the successful retrofitting of furnaces.