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Show Ambient Combustion Air A proven conventional high velocity low N O x burner was used as the development platform for an LNI ambient air burner with capacities up to 5.3 M W (18 x 106 BTU/h). Results of N A laboratory testing of LNI with the HiRam burner conclusively demonstrate that N O x emissions can be dramatically reduced by application of LNI method to burners fired with natural gas and ambient air. Figure 3 shows N O x emissions of an LNI burner compared with a conventional low N O x burner firing into the same furnace. The N O x emissions at 1367 K were 14 ppm (0.017 lb/106 Btu) for the LNI burner, compared with 50 ppm (0.06 lb/106 Btu) for the same burner fired in conventional mode. (Where ppm is used for N O x emissions in this paper, it is a volume concentration corrected to 3 % 0 2 in the products of combustion unless stated otherwise.) 1100 HiRam air/LNI N O x emissions; Conventional vs. LNI firing - r i ! - f - ! i ! ! 1200 1300 1400 Temperature, K 1500 1600 Figure 3 Oxy-fuel burners The LNI burner resulting from the ambient air work previously described has been augmented with the addition of oxygen capability to allow either mixed air/oxygen or 1 0 0% oxygen firing capability. N O x emissions are shown in Figure 4 for a configuration using an axially mounted 0 2 lance and identical injector locations to the ambient air burner. Figure 4 shows the dramatic difference in N O x emissions for the HiRam Oxy-LNI burner firing in conventional mode vs. LNI mode, both with 100% of the oxidant from oxygen. Ongoing work is focused on the potential offered by the use of remotely located oxygen injectors. HiRam 0 2 N O * emissions: Conventional vs. LNI firing 10000 o 100°- co <§) 100 . E Q. a. z • • ]• • • • I 1.8 M W gross heat input ! tL **f ** ! _ A LNI firing: 1 injector, L = 3 | a LNI firing: 3 injectors, L = 4 1200 1300 1400 1500 1600 Temperature,K Figure 4 Recuperated Combustion Air The development platform for low to moderate air preheat burners was a high velocity version of a proven 920 K air capable burner with capacity range upto12MW(40x106Btu/h). As can be seen from Figure 5, LNI results in a dramatic reduction in furnace N O x emissions, from 290 ppm (0.35 lb/106 Btu) for a conventional burner firing into a 1530 K furnace with 755 K preheat temperature, to 66 ppm (0.08 lb/106 Btu) for the LNI burner firing at the same conditions. 10-A, N O x emissions vs. temperature 1400 Temperature, 1600 Figure 5 Regenerative Burners The North American TwinBed™ II regenerative burner is characterized by air preheat temperature capability approaching to within 110 K of furnace temperature. Pre-LNI installations firing natural gas with furnace temperatures in the 1480 to 1540 K range could result in N O x emissions levels of well over 1000 ppm (1.2 lb/106 Btu) as a result of the high air preheat level. The application of LNI to the TwinBed™ II burner provides N O x emission levels less than 80 ppm (0.1 lb/106 Btu) at the same conditions. 4 |