CFD Simulation of High Temperature Air Combustion of Coal Gas at Different Air Straddle Angle

Numerical simulation was carried out on the High Temperature Air Combustion of coal gas in an industrial furnace with a multi-jet burner. A Beta-function PDF (Probability Density Function) combustion model was selected to simulate the gas combustion combined with the standard k-ε turbulent model. The radiation was simulated by a Discrete Ordinates method. Thermal NOx model was used to calculate NO emission. The effect of the straddle angle of the preheated air jets on the combustion characteristics was discussed. The results showed the smaller the straddle angle of the preheated air was, the better the mixing of the fuel, oxygen and the flue gas became, which resulted in a stable flame, an enlarged low-oxygen zone, an equable temperature distribution and a suppressed local high temperature. At 15% O₂ condition, when the straddle angle of the preheated air is 120°, the final NOx emission can be reduced about 65% compared with that when the straddle angle of the preheated air is 360°.