Experimental Studies of Gas-Liquid-Powder Flow in Moving Particles

An experimental study has been carried out of gas-liquid-powder flow in moving particles in one- and two-dimensional packed beds, simulating the complex four-fluid flow conditions in an ironmaking blast furnace which involves the upward flow of gas and unburnt coal/char and the downward flow of coke and molten iron and slag. It is shown that the contacts between packed particles are important for powder entrapment, and the presence of a liquid phase can significantly increase the powder hold-up and gas pressure drop. Only when the packed particles have significant downward velocity can the flow of powder and liquid be maintained without flooding. Depending on the flowing conditions, both steady and unsteady flows can be observed, giving the so-called operational and non-operational regimes. For the gas-glass powder-water system considered, the effects of solid, liquid, powder and gas flow rates on the two regimes have been quantified. The non-operational regime stems from the flooding caused by high gas and liquid flowrates and/or hanging caused by high powder and low gas flow rates. The operational regime expands with solid flow rate, and contracts with an increase in gas, liquid and/or powder flow rates. Implications of the findings to blast furnace operations are also discussed.