An experimental study has been carried out for gas-liquid-powder-solid four-fluid flow in a packed bed. This system simulates the complex 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 depending on the flow conditions, both steady and unsteady state flows can be observed, giving the so-called operational and non-operational regimes. The effects of solid, liquid, powder and gas flow conditions on the two regimes have been quantified. The non-operational regime stems from the flooding caused by high superficial gas and liquid velocities, and powder mass flux and/or hanging caused by high powder mass flux and low gas velocity. The operational regime expands with an increase in solid velocity, and contracts with an increase in gas and liquid velocities and/or powder mass flux.