Sizing Mist Eliminators for New and Retrofit Existing Separators

.

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