OCR Text |
Show k} = 4.4 X 109 exp (1.2~~10') [CH.]", [0,]'2S (3) k2 = 3.0 X 108 exp (1.2~~10') [CH.] [H2O] (4) k3 = 7.45 X lOIS r0 91 exp (1.6~~10') [HS5 [02] (5) k_3 = 3.83 X 1014 r los exp (4.1~~ 10') [H2O] (6) k4 = 2.75 X 107 exp (8.3~~107) [H2O][CO] (7) k-4 = 9.62 X 10" rO. s exp (1.2~~10') [H2] [CO2] (8) This scheme results in good temperature predictions. This is important as the majority of NO formation is highly temperature dependent. Numerical Predictions: Transport equations for the flow field were solved in Reynold-averaged form using the SIMPLE algorithm (1) for the pressure/velocity couplic1g. TurbNlence closure was obtained using the Reynolds Stress Model. The grid dependency of the numerical solution was investigated by using a finer grid in the combustion zone. The presence of high grid nodes in the combustion zone resulted in better agreement with experimental results. In this study, a fine non-uniform grid was generated in the combustion zone around and above the natural gas and oxygen inlet. The grid number was determined when the predicted results did not change significantly with an.increase in grid nodes. NO Formation in Flames Oxides of nitrogen, commonly known as NOx are produced as trace species from several sources, including stationary combustors such as furnaces. From nitrogen, there are three conversion routes to the final NO, N02 and N20, these are thermal, prompt and fuel. Because fuel-NO only arises from fuel bound nitrogen it is not considered as both cases involve the combustion of natural-gas. 4 |