Influence of 90-Degree Vertical to Horizontal Elbow on Gas-Particle Flow Characteristics of a Centrally-Fuel-Rich Primary Air Burner

The flow field of three geometry models 90-degree vertical to horizontal elbow, three-level conical rings concentrator and the combination of elbow and concentrator have been studied by simulation method. The velocity magnitude, relative mean axial velocity, relative mean radial velocity and axial particle volume flux has been analyzed. Elbow results in the asymmetry of its downstream flow field and the high speed airflow after conical rings shows lower speed and decays more quickly. Elbow influences the downstream particle distribution significantly. Elbow and conical rings cause a peak of axial particle volume flux, and the peak moves downwards. The peak value appears at y=0 on the axial position z/D=1.0. The concentration performance of the concentrator is enhanced by the elbow in some degree. The optimal distance between the outlet and the outlet of the primary air pipe had better be equal to the primary air duct diameter.