Experimental Characterization of Pressure Drop in Dry Demisters at Low and Elevated Pressures

The dry pressure drop over seven different wire mesh demisters has been measured experimentally. Four different system pressures were used, atmospheric, 2.0 Mpa, 5.0 Mpa and 9.2 MPa and three different gas/liquid systems. The experiments were performed in one low pressure rig and one high pressure rig. Air was used in the low pressure rig, and in the high pressure rig Nitrogen and a natural gas mixture were used. The porosity of the wire mesh demisters used in this study ranged from 93.4% to 98.5%. They were made of stainless steel and poly-propylene and three different geometrical shapes were used: layered, rolled and random. A new method has been established for calculating the physical mesh properties, mesh density, ρmesh, specific surface area, Smesh, and porosity, ɛ  , since the values provided by the manufacturer cannot always be used directly. The pressure drops could be fitted to a Hazen-Dupuit-Darcy type equation, ΔP/h=μUsup/K+CρUsup2, with good agreement for all systems tested and at system pressures up to 9.2 MPa. The form drag factor, C, could be taken as constant for each mesh type independent of the fluid system used. C was found to increase with decreasing mesh porosity. A limit has been suggested over which the viscous term can be disregarded. Based on the experimental data and the analysis of these, this limit is set at 5.0 MPa. Average values of the specific permeability, K, and the form drag factor, C, have been calculated for each mesh.