Modeling Studies of Fluid Flow below Flash-Smelting Burners Including Transient Behavior

摘要

Water-model experiments were carried out on 1:14-scale models of venturi, distributor, and jet-flow burners toascertain flow patterns at varying Reynolds numbers (60, 000 to507, 000) using time-lapse streak photography and video streakphotography. Digital particle image velocimetry (DPIV) was usedto determine the axial and radial velocities and to estimate theturbulence kinetic-energy field beneath the distributor burner. Inthe DPIV experiments, a temporal instability in the main jet exitingfrom the burner occurred at a Reynolds number =104,000, aStrouhal number ≈3×10-3, and a large expansion ratio(shaft/burner-diameter ratio=10). The main jetusually pointed away from the burner inlet but was alsoobserved to fluctuate and precess in a quasi-randomfashion. Recommendations are made for improvingflash-smelting burner performance by promotingconditions to eliminate prescessing. The use of higherReynolds numbers was recommended to improve both theuse of shaft volume and the mixing of the concentrateparticles and gas stream. A three-dimensional (3-D)mathematical model was used to simulate the water flowthrough the distributor burner, shaft, and settler.The predicted velocity field consisted of a main jetpointing away from the burner inlet and a largerecalculation zone in the center of the shaft. Thepredicted and measured velocity magnitudes comparedwell in the reticulation zone, but the steady-statemathematical model predicted higher velocity valuesin the main jet than were experimentally determined.