The Numerical Simulation Of Exhaust Gas Recirculation And Oxygen-Enriched Combustion On Gas-fired Furnace

Reasonable development and utilization of by product gas in the steelworks, orderly and efficient organization of combustion can relieve environment and energy crisis. It also has a far reaching effect on the development of the green economy. This study was based on the ideal of oxygen-rich combustion and exhaust gas recirculation technology. The combustion performance of a gas fired pulse test furnace at the thermal lab of Ansteel was studied by three-dimensional numerical simulation with software Fluent.This paper respectively analyzed and compared the effect of oxygen concentration and exhaust gas flow back ratio on temperature distribution, flow field, smoking emission and NO_x pollutants formation. We draw some conclusion as follows:（1） When oxygen-enriched air as the combustion-supporting, local high temperature zone appear in the furnace, the temperature of everywhere in the test furnace linearly increase with the increase of the oxygen concentration. When the high temperature exhaust gas mixed oxygen as the combustion-supporting, in the test furnace local high temperature zone area contract, the temperature of everywhere in the test furnace reduce with the increase of exhaust gas flow back ratio, and the reduction range is small amplitude increase. And using the high temperature exhaust gas mixed oxygen technology as the combustion-supporting can increase the uniformity of internal furnace temperature, and can inhibit the phenomenon of local high temperature.（2） When oxygen-enriched air as the combustion-supporting, the disturbance intensity of everywhere in the test furnace linearly decrease with the increase of the oxygen concentration. On the contrary, when the high temperature exhaust gas mixed oxygen as the combustion-supporting, the disturbance and turbulence intensity of everywhere in the test furnace linearly decrease with the increase of exhaust gas flow back ratio. And using the high temperature exhaust gas mixed oxygen technology as the combustion-supporting can increase enhance the effect of the convective heat transfer.（3） When adopting oxygen-enriched air combustion technology, the concentration of three atomic which is generated in the combustion increase, radiation ability improves obviously. There is a dramatic rise in the concentration of CO₂, H₂ O, N₂. Such as the burning of flue gas condensation, CO₂ concentration can reach 69%, increases the likelihood of CO₂ capture.（4） Adopting oxygen-enriched air combustion promote the generation of local high temperature type thermal NO_x. Contrast with inhibition of increase of nitrogen concentration, the effect of rise of temperature on the formation of nitrogen oxides is more prominent role.Adopting O_xygen-enriched combustion technology and the flue gas flow technology in the existing heating furnace, can improve the existing combustion effect, promote efficient use of energy, reduce pollutant emissions and save fuel consumption. Ultimately, achieve the dual purpose that improve the efficiency of energy and control environmental pollution in iron and steel enterprises.