Examination of liquid film characteristics in the prediction of pressure drop in a Venturi scrubber

Abstract

Liquid film characteristics in the prediction of pressure drop in a Venturi scrubber was examined by measuring the film flowrate, film thickness, and pressure drop by varying the injection orifice diameter, the throat gas velocity, and the liquid loading in a pilot-scale unit. The liquid mass flowrate flowing on the Venturi walls was found to be relatively independent of orifice diameter and decreased with throat gas velocities. The effect of increased liquid loading decreased the film flow on the orifice side and increased the same on adjacent walls. The average thickness of the liquid film on the walls was found to increase with orifice diameter on the orifice side, and with axial distance and decrease with orifice diameter on the adjacent-side walls, and throat gas velocity. The film velocities calculated were found to increase with throat gas velocity and liquid loading and continuously decrease along the axial direction. The distribution of the injected liquid flowing on the scrubber walls was found to depend on the liquid to gas ratio, throat gas velocity, liquid film thickness, axial pressure drop and relative velocity between the liquid film and the adjoining gas stream. An annular flow model, modified to include the variation in liquid film thickness using correlation developed during this work accurately predicted pressure drops for a wide range of operating conditions compared to the most commonly used models.