Investigation on residual swirl and flue gas imbalance in large tangentially fired boiler

There exists the serious problem of flue gas imbalance at the entry of hori zontal gas-pass in many large tangentially fired utility boilers used prese ntly in China. In this paper, the experimental and computational investigat ions on residual swirl and flue gas imbalance are carried out based on an i sothermal model of 600 MW tangentially fired boiler. The Porosity method an d the improved non-uniform QUICK scheme are presented in 3-D numerical simu lation in order to simulate the platen superheater correctly and reduce the pseudo-diffusion effectively. The numerical results agree well with the ex periment. The calculated results of flow field in furnace, diameter of actu al tangential circle, the distribution of swirling intensity along height o f furnace and the effects of the structures of nose and the platen superhea ter on residual swirl and velocity deviation are presented. The forming cau se and influencing factors of flue gas imbalance are discussed. Meanwhile, the means to diminish the deviation are introduced.