Numerical Simulation of Coal and Natural Gas Co-Combustion in a Rotary Kiln with Different Excess Air Coefficient

In this paper, numerical simulation of co-combustion of coal and natural gas was carried out aiming at a rotary kiln in Wulongquan limestone mine of WISCO. Combining the models of turbulent gas flow, gas-solid flow, heat and mass transfer and combustion of pulverized coal and natural gas, the temperature field, the species concentration field and the concentration of nitrogen oxides were displayed. The optimization approach was proposed by changing the excess air coefficient. The predicted results indicated that the excess air coefficient had great influence on flame temperature, flame length and the generation of NO_x, while the generation of NO_x was mainly connected with the temperature and oxygen concentration. All in all, the influence of the excess air coefficients on the combustion in the rotary kiln will provide important theoretical references to the optimized combustion of the co-combustion of coal and natural gas in the kiln.