Effect of the swirl angle on calcium carbide gas combustion characteristics of lower burner under annular shaft kiln

In order to solve the problem of high CO concentration in the emitted flue gas after adopting the flue gas recirculation technology in the annular shaft kiln, in this paper, the combustion characteristics of calcium carbide gas in swirl burners under the annular shaft kilns were studied by numerical simulation, the influence of fuel and primary air swirl intensity on combustion characteristics were studied, and the gas temperature distribution, pressure distribution and combustion products including CO, CO2 and NO was analyzed. The results show that the fuel gas swirl intensity has a great influence on the improvement of fuel burn-out ratio. The angle of the fuel gas blade increases, the maximum temperature of the combustion flame and the fuel combustion rate increase, and the CO content at the outlet of the burner decreases. When the angle of the fuel gas blade increased from 30o to 55o, swirl number increased from 0.41 to 1.02, the CO content at the inner sleeve position decreased from 8929 mg/m3 to 2467 mg/m3. The results also show that the effect of the primary air swirl intensity on reduce CO emissions and NOx formation was not obvious.