| OCR Text |
Show The parameters which affect the rate of N O x formation and/or the combustion zone mixing and heat release patterns for LNI combustion are: The orientation of fuel injector to oxidant injector (offset distance and angle) Oxidant velocity leaving the oxidant injector (typically the burner tile) Fuel stream velocity leaving the fuel injector The number of injectors Oxygen level in combustion products in furnace Furnace temperature Air preheat temperature Furnace geometry The first four of the above parameters are burner dependent, the last four parameters controlled by the application. Development effort focused on optimized combinations of the first four, and quantification of the effects of the last four parameters on emissions. As the parameters interact, application parameters can influence the selection of particular combinations of burner parameters. An LNI burner is required to perform two functions. It must operate as a conventional burner, providing a flame holder and mixing of fuel and oxidant to raise the furnace temperature above autoignition to sustain LNI combustion. It generally serves as the oxidant nozzle for LNI combustion. High velocity burners are ideally suited to both functions. In conventional firing mode, high velocity burners are inherently low N Ox producers as they entrain significant cool furnace gases into the flame envelope prior to completing combustion of the fuel. The reduced port tile which is typical of high velocity burners provides an excellent oxidant nozzle for LNI combustion by entrainment of cool furnace gases with the oxidant stream prior to mixing with the fuel. Our development programs to date have been devoted to commercial LNI products in the following categories: Ambient combustion air, natural gas fuel. Combustion air preheated by recuperator (air preheat temperatures typically from 200 to 1200 F), natural gas fuel. Regeneratively preheated combustion air (air preheat temperatures typically from 1000 to 2000 F), natural gas, #2 and #6 fuel oil. Oxygen enriched and pure oxygen combustion, natural gas fuel. 6 |
