To MortenA, I beg to disagree.
For gas-liquid systems -the case now under consideration- both cyclones and demister pads have their useful applications depending on the liquid/vapor load and particle sizes.
Cyclones function by using centrifugal force; demisters are impingement separators.
Demisters are effective entrainment separators in evaporators, absorption towers, distillation columns, etc. Their function is based mainly in increasing the size of drops so that gravity drip off can rapidly occur without the drops being carried away by the gas.
Knitted mats with a surface area of 400 m2/m3 have shown 99.9+ % removal efficiency. Even general purpose standard mats have shown removal efficiencies of 99.5+%. For services containing solids or "dirty materials" fish-bone woven mats with a free volume of 99% and a surface area of 160-230 m2/m3 have been reported to operate with 90+% removal efficiency. Mesh demisters excel at low loads of about hundreds of ppm by volume, and particle sizes of above 10 [μ]m.
Then there are silicone impregnated (polyester or glass) fibre mist eliminators with diameters down to 1.3 [μ]m to catch submicron acid fogs.
Zig zag vanes are the preferred separator for the same loads as demisters, but for larger particle sizes reaching a size of 0.5-1 cm.
Cyclones, particularly wet cyclones, are useful for high loads and a wider range of particle sizes. From published data, only when the particle dimensions are 10 times the "cut size" the collecting efficiency reaches 99%. Cut size is defined as the diameter of particles of which 50% are collected. To avoid re-entrainment special design provisions are taken.
There is a plethora of literature on the subject. And new developments are offered by manufacturers of separators every now and then.