Quantification of powder holdups in the presence of a cavity with lateral gas-powder injection in a packed bed

The lateral flow of gas-powder through a packed bed in a cold model is studied to understand the flow and holdup behaviour of powder in the presence of a cavity, nozzle (tuyere) protrusion, and decreasing gas condition, a system used in the ironmaking blast furnace. Experiments conducted in the current study included a two-dimensional (2D) slot-type packed bed. A previously published mass balance and elutriation velocity concept formed the basis for accurately quantifying the static and dynamic powder holdups. Experiments conducted under different conditions such as powder size and flux, gas flow rate, and packed particle density and size resulted in quantifying the powder holdups. The pressure drop in both horizontal and vertical directions is studied in all two-phase flow experiments. The formation of the static holdup with time in the packed bed is studied. The reproducibility of the experiments was confirmed. The static holdup inside the packed bed at various locations along the vertical direction (i.e., height) is also quantified. The static holdup correlation developed based on experimental data resulted in a 95% confidence interval. Static powder holdup increases with a decrease in the superficial gas velocity, an increase in the size of the powder particle, and powder flux. Dynamic holdup also showed a similar trend.

Automated summary

This study investigates the lateral flow of gas-powder through a packed bed to understand the behavior of powder in the presence of certain conditions, such as a cavity, protrusion, and decreasing gas condition. The experiments conducted in a two-dimensional slot-type packed bed successfully quantified the static and dynamic powder holdups under different conditions. The results show that the powder holdup increases with a decrease in gas velocity, an increase in powder size, and powder flux.