SOME EXPERIMENTAL LIQUID SATURATION RESULTS IN FIXED-BED REACTORS OPERATED UNDER ELEVATED PRESSURE IN COCURRENT UPFLOW AND DOWNFLOW OF THE GAS AND THE LIQUID

The effect of pressure (0.3 less-than-or-equal-to P/MPa less-than-or-equal-to 5.1) on the total liquid saturation (measured by RTD method) of a fixed bed operated with cocurrent gas and liquid in both upflow and downflow is investigated. For upward flows, the liquid saturation is greater than for downward flows regardless of the operating pressure. However, in the pulsing flow regime and at high gas velocities, the same asymptotic value is observed for both flow directions. The liquid saturation increases with pressure, mass flow rates being constant, but decreases when the liquid viscosity is decreased, independently of the flow direction and the operating pressure. For low gas velocities (u(G) < 1 cm/s), the total liquid saturation no longer depends on the pressure. For higher gas velocities (u(G) > 1-2 cm/s) and nonfoaming liquids, the drift flux can provide an acceptable estimation technique of the liquid saturation if experiments under high pressure could not be conducted.