Separator Efficiency

[RRE]

I was asked recently to provide a % efficiency value for a wellsite separator (operating in natural gas, some oil and produced water service). I provided a value of ~90%. I understand that if you use well designed mesh pads, vanes, or other internals (cyclonic, etc) the efficiency is much higher for phase separation.

Is my value of 90% for a "typical" well site separator efficiency(lucky to have a mesh pad present) anywhere close to reality??

 

[25362]

There are general purpose standard mats that claim efficiency values above 99%; for example, wire mesh demisters with 100 mm minimum thickness and thread diameters 0.25 mm.

According to Campbell (Gas Conditioning and Processing, 1972) a formula for the recommended gas velocity over the total cross section of the mat not blanked by supports

V = 0.107 [([ρ]_L-[ρ])/[ρ]]^0.5 m/s​

where
[ρ]_L = density of the liquid, kg/m³
[ρ] = density of the gas, kg/m³

has given good results for separation of oil and natural gas under high pressures, for horizontally mounted wire mesh demisters placed at least 250 mm above the liquid surface.

 

[TrevorP]

The data I have for well designed knock-out pots (not necessarily as per your application), without a meshpad, and not including cyclones etc. give an efficiency in the range 80 - 98%. 90% seems fairly typical. Efficiencies of 95%+ can be expected with cyclones, and up to 99.9% with demister pads.