Class project at Texas A&M University

1. Separator Design
Abita Antony
Cyril Iyasele
Natural Gas Engineering
March 25, 2010

2. Outline
 Introduction
 Separator configurations
 Demisters
 Sizing separators
 Summary

3. Introduction to Phase Separation
 Physical separation of natural gas to its component phases
 The temperature and pressure of the gas dictates phases present
 Occurs in a pressure vessel provided for that purpose
 Mist extractors-wire mesh, vanes, or baffles- reduce liquid entrainment

4. Separator Configurations
 A separator is a vessel used to separate a mixed-phase stream into gas
and liquid phases that are ‘’relatively’’ free of each other
 Principles used to achieve physical separation of gas and liquid include:
• momentum • gravity settling • coalescing
Large volume of total fluid
Large amount of dissolved gas
High gas-liquid ratio
Low total gas volume

5. Demisters
 Also known as mist extractors
 Removes suspended mist or liquid entrainment
 Liquid removed is coalesced into larger droplets

6. Sizing Separators
Specifying separators requires:
 Pressure, temperature
 Flow rates
 physical properties of the streams
 Degree of separation required
Specifications include:
 Diameter
 L/D ratio
 Vapor Space height
 Liquid residence time

7. Sizing Separators

8. Sizing Separators
Parameter Feed Vapor Outlet Liquid Outlet
Flow rate 44 MMscfd 42.42 MMscfd 1.575 MMscfd
Pressure 613 psia 613 psia 613 psia
Temperature 68 F 68 F 68 F
Separator Worksheet
Vapor Liquid
Components Feed (mol%)
Outlet(mol%) Outlet(mol%)
Nitrogen 0.20 0.21 0.00
CO2 4.50 4.65 0.49
H2 S 1.80 1.85 0.48
C1 78.31 81.08 3.51
C2 4.10 4.22 0.78
C3 3.10 3.15 1.70
iC4 2.00 1.99 2.30
nC4 1.50 1.47 2.29
iC5 0.70 0.65 2.14
nC5 0.50 0.45 1.90
C6 0.30 0.22 2.44
H2 O 3.00 0.07 81.97
Total 100.00 100.00 100.00

9. Sizing Separators
Computer Simulation Method
EOS: Peng-Robinson

10. Sizing Separators
Horizontal Separator (HYSYS)

11. Sizing Separators
Vertical Separator (HYSYS)

12. Sizing Separators
Hand Calculation Method

13. Sizing Separators
GPSA - Hand Calculation Method (Various Separator Configurations)
Without Demister
 Case I: Horizontal separator
 Case II: Vertical separator
With demister
 Case III: Horizontal separator (<10 ft ; >10ft)
 Case IV: Vertical separator

14. Sizing Separators
Cases I & II: Horizontal & vertical separators without demister
Horizontal Without Demister
Vertical Without Demister
Diameter (ft) Length (ft) L/D ratio
Diameter (ft) Length (ft) L/D ratio
2.50 11.80 4.72
5.43 19.02 3.50
2.80 10.50 3.77
3.14 9.42 3.00

15. Sizing Separators
Cases III & IV: Horizontal & vertical separators with demister
Only for :Horizontal >10 ft
Vertical With Demister Horizontal With Demister
Diameter (ft) Length (ft) L/D ratio
Diameter (ft) Length (ft) L/D ratio
1.40 7.00 5.00
2.87 10.05 3.50
1.50 6.50 4.36
1.80 5.40 3.03

16. Horizontal Separator with Demister- Case II ( L >10 ft )
L changes with Vt
L/D ratio:
b/w 3 ~ 5
Vt changes with L
assumed Length (ft) Terminal Velocity (ft/s) Diameter (ft) L/D ratio
L Vt Dv r
11 1.45 0.85 13.00
12 1.52 0.74 16.25
13 1.59 0.65 19.94
14 1.66 0.58 24.11
15 1.72 0.52 28.77

17. Summary
GPSA GPSA
HYSYS HYSYS GPSA (Vertical GPSA (Vertical
(Horizontal (Horizontal
(Horizontal) (Vertical) w. Demister) w/o Demister)
w. Demister) w/o Demister)
L/D ratio 3.00 3.00 3.50 3.50 3.00 3.50
Length (ft) 13.50 5.40 15.75 10.05 9.42 19.02
Diameter
4.50 1.80 4.50 2.87 3.14 5.43
(ft)

18. Next Design Stage
Separator outlet vapor stream
Parameter Vapor Outlet H2 S
Flow rate 42.42 MMscfd
Sweetening
Pressure 613 psia
CO2
Temperature 68 F
Components Vapor Outlet(mol%)
Nitrogen 0.21
CO2 4.65
H2S 1.85
C1 81.08
C2 4.22
C3 3.15
iC4 1.99
nC4 1.47
iC5 0.65
nC5 0.45
C6 0.22
H2O 0.07
Total 100.00

19. Thank you