Vane mist eliminators can be used in tandem with wire mesh pads to control the amount of liquid pooling within the pad. Contacting the bulk of vapor entrained liquids with vane mist eliminators prior to flowing to the wire mesh pad enhances the pad’s ability to quickly drain. This application also increases the effective operating range of the demister pad, particularly during unusual liquid loading scenarios. Figure P-5 plots the liquid scrubbing performance of a vane mist eliminator installed upstream of a woven wire mesh pad.
In addition to the added removal capacity of vanes, another reason for enhanced mesh pad performance in tandem configuration is the straightening of the gas flow entering the pad. Swirling and lateral gas flow entry promotes pooling in the pad, thus increasing the likelihood of pad flooding and re-entrainment.
Combination installations are well suited for minimizing mesh pad fouling and corrosion. Fouling solids are effectively removed in the vane section and corrosive liquids that pool in the mesh pad can be minimized.
The result of combination installations is reduced pad fouling and corrosion, as well as enhanced removal efficiency over a wide range of loading. It is a good retrofit alternative for systems that are operated beyond original design. Figure P-6 illustrates how a combination installation might look.