Numerical investigation of pulverized coal combustion and optimization of operating mode in multi-burner boiler

摘要

Aiming at the optimization of the operation condition, a general numerical method for calculating pulverized coal combustion in a full-scale furnace fired tangentially at four corners is adopted. Two-equation "k- epsilon " turbulence model is used for the gas phase and the Lagrangian technique for the particle phase. Two-competing reactions model for the coal devolatilization and PDT method for the combustion of the gas phase are employed. The numerical simulations are performed by means of CFD software (CFX4.2). Three different operating conditions are applied, of which one is changing air distribution including in pagoda, waist drum and uniform type air distribution, one is applying a refractory-faced zone for vapourizing surfaces, another is adjusting elevation angle of burners and the order of the burner levels. The temperature fields for all operating condition are presented. The effect of operating condition on ignition and the flue temperature at the inlet of screen type heat exchanger are analysed. The results from numerical calculations are in good agreement with the phenomenon observed in industries furnace.