Vane Pack "k" Factor

[maddocks]

Can anyone advise on allowable "k" factors for vane pack separation? This is a Peerless PBX type unit operating at about 885 Psia on sweet (0.65 gravity) gas.

 

[TD2K]

I can't comment on that specific vane pack but we had some others that used a rho v squared factor (lb/ft3 and ft/sec) of 30 in coming up with the design area required.

These were also a lower pressure than you are working with, I don't know if there is a derate factor associated with them similar to demister pads but I wouldn't be surprised.

 

[EmmanuelTop]

In general, gas load factors (or K-values) used for sizing vane packs are in the range of 1.00-1.25 m/sec for atmospheric pressure conditions. Similarly to demister pads, pressure de-rating factor is applied to predict performance at elevated pressures.

I wouldn't recommend using vane packs in systems above 10-15bar since their performance deteriorates exponentially above these pressures - especially if high liquid removal efficiency is required (e.g upstream of mol sieve dehydrators or compressors). A usual way to go is to employ:

1. Vessel large enough (no one can beat the gravity)
2. Mistmat as primary coalescing element, 100-150mm thickness, stainless steel
3. Cyclonic devices as secondary coalescers

We've had quite bad experience with vane packs in our Mol Sieve unit (KO drum) which operates at 70barg pressure. This system simply doesn't work and I would never believe to separator internals vendors, regardless of what they say.

 

[EmmanuelTop]

I apologize,
Gas load factors mentioned in my post should be:

0.100 - 0.125 m/sec