Numerical simulation of the co-combustion process of gas-solid two-phase fuels in a rotary kiln
DING Jiawen
LIU Peng
LIN Shuxing
YANG Jiabin
LAN Xiaoyu
DONG Qiji
MA Yingjie
Abstract：Due to the problems such as large energy consumption and waste emissions of industrial furnaces and low utilization rate of waste heat and residual energy in the rotary kiln-submerged arc furnace process,it is of great signif-icance to utilize the waste heat and residual energy of the flue gas in the furnace for improving the energy utilization ef-ficiency of the RKEF process and reducing the emission of polluted gases.A five-channel burner for the rotary kiln was designed and used for the mixed combustion of furnace gas and pulverized coal.The computational fluid dynamics method was adopted to conduct a numerical study on the mixed combustion process of gas-solid two-phase fuel in the rotary kiln,and the influence of the addition of furnace gas fuel on the temperature field,combustion characteristics and NOx emissions in the rotary kiln was analyzed.The study found that when gaseous fuel is mixed into the pulver-ized coal,due to the significant velocity difference between the axial flow air and the secondary air,the high-temper-ature secondary air is entrained by the axial flow air,forming an outer circulation zone,which can significantly in-crease the combustion rate of the pulverized coal and optimize the temperature distribution pattern inside the rotary kiln.When the mixed fuel of furnace gas and pulverized coal is used for combustion,the peak temperature and the temperature in the roasting zone in the rotary kiln both show a downward trend.That is,the incorporation of gaseous fuel promotes the early start of the combustion process of pulverized coal,significantly shortens the length of the black firehead,and makes the position of the roasting zone closer to the burner,resulting in a stable"club-shaped"ap-pearance of the flame.With the addition of furnace gas fuel,the peak temperature and the temperature in the roasting zone in the rotary kiln both decrease,which helps to alleviate the occurrence of ring formation.The addition of fur-nace gas fuel can also effectively reduce the NOx emissions.The NOx content at the outlet of the rotary kiln drops from 655 mg/m3 to 327 mg/m3,and the NOx emissions are reduced by 50.1%.
Keywords：gas-solid two-phase fuelnumerical simulationmixed combustionrotary kilnfive-channel burnerflue gas recoveryfluid dynamics methodcombustion rate
Publication Date：2025-05-31
Pages：6( 63-68 )