sizing mist eliminators for new and retrofit existing separators
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Sizing Mist EliminatorsFor New or Retrofit Existing
Separators
Principles of Gas/Liquid Separation
♦ Inertial Capture in Vanes and Mesh
○ Droplet Size○ Strand Diameter or corrugation spacing○ Gas Velocity○ Liquid Density relative to gas density ○ Gas Viscosity○ Pad Density and Thickness
♦ Interception Capture
♦ Brownian Capture
Figure 15. Droplet capture by Brownian motion in a Fiber candle or panel
Mesh Vane Mesh/Vane CommentsGeneral Purpose
(9# Density)
99% of
10 Micron
99% of 30
Micron
None Critical Equipment downstream or where
Mesh plugs
Improved DesignHigh efficiency & 10% high capacity
99.9% 5
micron
To protect compressors
Catalyst & beds, etc.
High efficiency high
Liquid load
99.9% 5 micron To avoid mesh flooding
Medium efficiency &
50% extra high capacity
99.9% 8 micron
Double Pocket Vane
In applications where
Mesh plugs
Ultra high efficiency 99.9% of 1 micron
99.9% of 1 micron To minimize solvent losses (MEA, MDEA, etc)
Ultra high efficiency 50% extra capacity
00.0% of 1 micron Double Pocket Vane
Sizing Mist Eliminators
Souders – Brown Equation
K = PL ־ PG
VG
PG
K = vapor load factor (Souders-Brown velocity)
VG = gas velocity
PL = liquid density in same units as PG
PG = gas density in same unit as PL
Recommended Vapor Load Factors
Mesh Pads K=0.20-0.40
Vane Unit Vertical Flow K = 0.45 (max) (no hooks)
Vane Unit Vertical Flow K=0.65 (max) (no hooks)
Double Pocket Vanes (Vert/Horzt Flow) K=1.2 (max)
Mist Eliminator Sizing Calculation Example:
Flow Rate: 100 ACFS Pg: 1.25lb/ft3
Pressure: 400psig Pl: 1.21lb/ft3Area required 100ACFS Vd1
Vd1 = .30 √ 42 -1 = 1.7
1.25
K=0.30 (mesh pad)Wt: 4000lbs
K=0.5 (vane)Wt: 2800lbs
K=1.1 (DP vane)Wt: 1500lbs
Vane Profiles
AmistcoSix-Pass
Vane Unit
AmistcoDouble-Pocket
Vane Unit
Challenges to overcome when Providing High Capacity in smaller Separators
• Limited Vessel diameter or height• Restricted disengaging space for the incoming gas / bad
gas distribution• High gas velocity creates turbulences in the liquid phase
– reduces oil/water gravity separation• Higher mist loading in the gas phase – could flood the
M.E.• Build new support structure with welding to the vessel
wall (Retrofit)
Configuration
Standard One Bank
Alternative Configuration
2 Bank 4 Bank
Double Expansion Ring
Support Ring Frame Installed
Installation of support Frame
Knockout Drum Retro-fit
Support Ring Installed without welding
Vane Retro-fit
Vane Retro-fit
Vane Retro-fit
Retrofit Vane/Mesh
Double-Pocket Vane Retro-fit
Rukovena Consulting
Vane with Support Frame
Inlet distributorsImpact on Separator’s Performance
A
A
CFD velocity profile at A-AIdentified poor gas
distribution as a cause. Red velocity is 3 times design velocity and 4 times green
velocity
Inlet Diffuser view 1
Inlet Diffuser view 2.
Typical Situation
Corrected Situation: High Capacity/High Efficiency