586 / 2019-01-19 17:25:13

Study on flow field and dispersion characteristics of top-blowing lance based on large eddy simulation of gas-liquid two-phase flow

LES;dispersion coefficient;swirl spray gun;vortex structure

全体主题 > 数值模拟、建模与CFD

Electric furnace spray gun is a core process in the lean electric furnace smelting system. Its main function is to transport nitrogen and fuel into the molten slag layer to participate in the reaction, thus completing the clarification and separation of slag and matte. The degree of mixing of the two-phase flow in the spray gun and the stirring effect on the slag layer after the two-phase flow is sprayed can directly affect the smelting efficiency. More and more researches at home and abroad tend to optimize the spray gun and improve the nozzle structure of the spray gun in order to achieve energy saving. As the core equipment of the lean electric furnace smelting system, the spray gun is the main factor affecting the efficiency and one of the representatives of the advanced level of the melting technology. Damage to the gun is one of the reasons that affect the life of the gun. Due to the swirling effect, the gas-liquid dispersion in the spray gun is enhanced, the heat transfer is enhanced, the life of the spray gun is effectively improved, and the stirring ability of the spray gun in the molten pool is enhanced. The large eddy（LES） method was first proposed by meteorologist Smagorinsky and was originally used to predict weather development. Specifically, the small-scale pulsation is first removed from the turbulent pulsation by the filtering method, and the filtered velocity pulsation is called the solvable turbulence because there is no pulsating component below the filtering scale.The top-blowing lance is of great significance to the lean electric furnace smelting system. Based on the large eddy simulation method, the dispersion coefficient and flow field distribution of the top-blowing lance with different geometry cyclones are analyzed. The results show that with the increase of the number of swirls, the dispersion coefficient decreases from 0.15~0.7 to 0.001~0.05, the dispersion effect is obviously improved, and the number of swirler blades increases, which has a positive effect on the dispersion effect. An obvious vortex structure is attached around the cyclone, and the vortex structure effectively enhances the turbulence phenomenon and enhances the gas-liquid dispersion effect. The combined effect of the cyclone on the tangential and axial velocity of the fuel facilitates the uniform dispersion of the gas in the liquid, while the larger tangential velocity enhances the mixing effect of the molten pool, the penetration depth is reduced, and the amount of splashing is reduced.