(30a) Successful Design and Implementation of An Enhanced Selective Non Catalytic Reduction (ESNCR) System for a Refinery Boiler

Selective non-catalytic reduction technology (SNCR) is an effective and economical method of reducing NO_X emissions from a wide range of industrial combustion systems. It is widely known that the SNCR process is primarily effective in a narrow temperature window, around 900 to 1,000ºC, and that high CO concentrations can both shift the temperature window and limit its effectiveness. However, in a lot of refinery boilers, the flue gas temperature is lower than the normal SNCR temperature. Therefore, in order to design a system that can achieve optimal NO_X reduction performance, careful use of design tools are needed to identify the best location for reagent injection, for maximizing residence time and for minimizing the CO impact. In some cases, additives, such as hydrogen can be used to enhance SNCR (ESNCR) NO_X reduction performance when flue gas temperatures are less than optimal. GE Energy has recently successfully designed and implemented an ESNCR system for a refinery CO boiler and achieved significant NOx reduction (>40%) with less than 10 ppm slip. This paper presents the process design methodology consisting of computational fluid dynamics simulation and chemical kinetics predictions, and discusses the optimization test results. The program demonstrates that the hydrogen enhanced SNCR technology can be effective for refinery boiler NOx control.