| OCR Text |
Show while simultaneously improving the system efficiency. The traditional benefits of using oxygen in combustion are outlined. Theoretical NOx reduction, experimental results, industrial experience, and conclusions are discussed. OXYGEN BENEFITS IN COMBUSTION This section discusses the traditional benefits of using oxygen in combustion processes. They include reduced flue gas volume, reduced particulate emissions, increased productivity, and increased efficiency. Combusting gaseous fuels like natural gas with pure oxygen instead of air has many important benefits which are all related to removing the nitrogen component from the oxidizer. The combustion of methane with air is shown in (1): CH4 + 202 + 7. 52N2 ~ C02 + 2H20 + 7. 52N2 ( 1 ) The combustion of methane with pure oxygen is shown ln (2): ( 2 ) The total molar flow volume in (1) is 3.5 times larger than that in (2). This is important in industrial applications because the larger flows require bigger fans, ducts, and gas treatment equipment. The larger flows may also produce more particulates in the exhaust stream because the higher gas velocities through the system can entrain dust from the materials being heated. The inert nitrogen substantially reduces the flame temperature. Figure 1 shows the adiabatic flame temperature for a methane flame as a function of the percent oxygen in the oxidizing gas l . The higher flame temperatures can significantly lncrease Figure 1: (deg F) (deg K) 5300.---------------------------------------.3200 5100 4900 4700 4500 4300 4100 3900 3700 (Westbrook, 1986) 3100 3000 2900 2800 2700 2600 2500 2400 2300 3500~--------~--------~--------~------~2200 20 40 60 80 100 Percent 02 in N2 Adiabatic flame temperature versus percent oxygen in the oxidizing stream consisting of oxygen and nitrogen. 1990 AFRC Symposium -2- October 1990 |
