The document provides instructions for starting up a Separex membrane system. It outlines the following key steps: 1. Pressurizing and warming up the pre-treatment section slowly to avoid damage, reaching the target pressure and temperature. 2. Once pre-treatment is ready, opening isolation valves to pressurize the initial membrane bank slowly while maintaining a nitrogen blanket. 3. Gradually reducing the permeate pressure once the membrane bank reaches operating pressure and temperature. 4. Repeating the pressurization and warming steps for additional membrane banks if more than one is installed. The startup process is designed to safely bring the system online in stages to protect both the equipment and membrane elements.

1. © 2017 UOP LLC. A Honeywell Company All rights reserved.
Introduction
Separex™ Membrane System
 PV Gas Ca Mau GPP Project

2. • Membrane Separation Principles and Overview
• Pre-treatment Equipment and Operations
• Membrane pre-commisioning activities and element loading
• Startup/Shutdown
• Normal Operations and Troubleshooting
Course Learning Objectives
1

3. Regions of Use for CO2 Removal Technologies
1000
100
10
1.0
0.1
Scavengers
MolSiv ™
PSA
Selexol™
Amine Guard™ FS
Membrane
Benfield™
PartialPressureAcidGasinFeed,psia
Partial Pressure Acid Gas in Product, psia
0.001 0.01 0.1 1.0 10 100
1000
100
10
1.0
0.1
2

4. Block Flow Diagram
3

5. Do’s
 Bulk CO2 removal
 Variety of CO2 feeds
 Offshore, remote, difficult
locations. modular
 Medium to high pressure
(> 600 psig)
 CO2 is a product
(re-injection, fuel gas)
Don'ts
 Try to get CO2 to ppm
levels (like feed gas for
LNG production)
 H2S to ppm levels
 Low feed gas pressure
Separex Membrane – Do’s and Don'ts
4

6. Membrane Principles
• Membranes separate components by a solution and diffusion
mechanism
- More soluble components permeate quicker
• Not a filtration process
• Separation is not perfect
5

7. Relative Permeation Rates
H2S, CO2, O2
H2O, H2, He
Fastest  Most Soluble
 Least Soluble
CO, CH4, N2, C2+
Slowest
CO, CH4, N2, C2+
H2S, CO2, O2
M
e
m
b
r
a
n
e
6

8. Selectivity of CO2 Membranes
UOP 4375C-06
UOP Confidential
Fast
Slow
HighPressure
LowPressure
H2O, H2S
CO2
(+ small amount of hydrocarbons)
Hydrocarbons
7

9. Driving Force
M
e
m
b
r
a
n
e
PCO2
High Pressure
(Feed)
Low Pressure
(Permeate)
Pressure Differential Across The Membrane
PCO2
8

10. Membrane Elements – Spiral Wound
9

11. Spiral Wound Membrane Element
8” Dia x 40” Long
40 lbs (18 kg)
10

12. Element Permeate Tube
11

13. Spiral Wound Membrane Tube
Residual
FeedPermeate
Inlet Seal
(U-Cup)
Membrane
Elements
Membrane
Housing
Permeate Tube
Clamp
Permeate
Standoff Tube
Taper-Lok
Enclosure
Taper-Lok
Enclosure
12

14. © 2017 UOP LLC. A Honeywell Company All rights reserved.
Design Basis
Separex™ Membrane System
 PV Gas Ca Mau GPP Project

15. PV Gas Membrane Pretreatment
 Performs well on light clean feed gas
 6-Month / 1-year maintenance cycle
 No dew point control downstream of cryo unit
Residue Gas
Cooler A-3001Feed
Membrane
X-4092
Filter
Coalescer F-4091
14

16. PV Gas Separex and Pretreatment Skid
15

17. Process Flow Scheme Diagram
16

18. Design Basis
• Sales Gas Specification:
- Maximum CO2 content: 8.0 mol%
- Minimum Gross Heating Value: 37.0 MJ/m3
• After separating the NGLs from the feed gas,
- Residue gas CO2 concentration > the specification of 8.0 mol%.
- Gross heating value lower than the required minimum of 37 MJ/m3.
• A small amount of CO2 will be removed in the membrane unit to
adjust the residue gas so that it is within the specifications.
• The low pressure, CO2 rich permeate will be used for fuel in the
HMO heaters and in the dehydration unit regeneration gas heater.
17

19. © 2017 UOP LLC. A Honeywell Company All rights reserved.
Membrane Pre-Commissioning Activities & Loading
Separex™ Membrane System
 PV Gas Ca Mau GPP Project

20. Pre-Commissioning
Understand:
• Pre-commissioning Activities
• Personal Protective Equipment and Safety
Considerations
• Pre-commissioning of Pretreatment
• Pre-commissioning of Membrane
• Leak Testing
19

21. Pre-Commissioning Main Activities
• P&ID Verification – Field verify including “as-built” mark-up
• Equipment Verification – Installed per design
• Line Cleaning – Confirm piping and headers been cleaned
• Load vessels – Filter cartridges and adsorbent
• Membrane Tubes – Clean membrane tubes and load elements
20

22. Pre-Commissioning Main Activities
• Instrumentation – Field verify instrumentation have been properly
reinstalled
• DCS/Instrumentation – Complete checks of field loops and DCS
interface
• SDV and BDV – Set and confirm limit switch operation
• Control Valves – Set and confirm valve movement
• Logic Check – Confirm functionality & verify proper
responses/actions
• ESD /DCS – Perform ‘dry tests’ to confirm C&E and field verify for
proper actions
• Line up PRVs – Confirm isolation valves in proper positions
including car seals or locks installed
• Leak Test – Audit flange tightness records. In controlled manner
test to operating pressure to confirm no loose connections
21

23. Filter Coalescer
outlet
inlet
Tubesheet
Standpipes
(adaptors)
Pre-separator
Liquidlevel control
Seprasol™Plus cartridges
22

24. Filter Coalescer Drawing
23

25. Main Pre-commissioning Activities
• Inspect F-4091 vessel
• Clean as needed
• Install filter coalescer cartridges
• Membrane Activities
- Remove permeate headers and Taper-Lok flanges
- Clean tubes
- Load membrane elements
- Reinstall Taper-Lok flanges and headers
- Leak test
- Nitrogen blanket
24

26. Remove Taper-Lok Flanges
• Erect scaffolding at residual end
of membrane skid if needed
• Prepare work area for removal
of Taper-Lok flanges
• Confirm each pair of Taper-Lok
flanges clearly marked to aid
reinstallation
Residual end Taper-Lok flange
Feed end Taper-Lok flange
25

27. Taper Lok Ring and Permeate Tube
Taper-Lok
metal seal
rings
Taper-Lok flange
with permeate
standoff tube
Poor practice – 2” flange resting on grating
26

28. Tube Cleaning
• Tube cleaning critical step prior to membrane loading
• Required to remove:
- Dirt
- Debris
- Scale
- Rust
- Corrosion inhibitor applied during fabrication
 Cleaning will take more time
• Prevents contamination of membrane elements, leading to
poor performance
• Not complicated
27

29. Tube Cleaning
• Pull rags/cleaning pig back and forth through tubes
• Use solvent like mineral spirit or paint thinner
• Continue until clean
• Let any excess solvent weather off before loading membranes
Tube cleaning is important but not complicated
28

30. Tube Cleaning
• Rags, foam, etc.
• Pull back and forth through tube with rope
29

31. Tube Before & After Cleaning
Before Cleaning After Cleaning
30

32. Before You Begin Loading
• Develop a loading plan
• Know which tubes will be opened
• Know what you will do with removed elements (if applicable)
• Know which elements will be added or replaced
• Have log prepared to record element serial numbers and location
inside the tube
• Develop staging plan (clamps, pins, vacuum grease etc.) and
equipment
• Ensure no rain or humidity > 80% expected. If not possible:
- Plan for shelter
- Plan for humidity control
UOP will advise on membrane loading activities at site
31

33. Loading Precautions
• Do not drop membrane elements
• Do not expose membrane elements to water or excessive
moisture/humidity
• Do not expose membrane elements or tubes to excessive
particulates (sand, etc.)
• Do not allow element to rest on edges or points
• If element is dropped or damage suspected, inform the UOP
technical advisor
• Open membrane packaging immediately prior to installation
(staging consideration)
• Keep tubes covered that are not being worked on
32

34. Loading Precautions (continued)
• Do not apply excessive force when snapping in clamp
• Do not twist or turn elements once they are connected
• Do not allow elements to hang on element connections – proper
support required until the newly connected element is adequately
inserted into the tube
• Do not allow Taper-Lok flanges to hang on element connections –
use support rods
Always avoid excessive load onto elements by providing proper support
(tray & support rods)!!
33

35. Element Loading
• Evenly apply grease to U-cup seal of next element
• Install o-ring onto centering ring
• Apply vacuum grease to o-ring
• Stick greased o-ring/centering ring onto flange of first
element
• Place next element permeate tube against o-ring/centering
ring on the first. Install clamp and pin
• Push the element string into tube leaving ~ 6” (15cm) outside
• Repeat until the proper number of elements have been
installed
34

36. Loading Procedure (cont.)
• Install Taper-Lok metal seal ring
- Seal ring can be reused if not damaged
• Place greased o-ring/centering ring against permeate flange.
Push Taper-Lok flange until its ‘stand-off’ tube flange is
against the o-ring/centering ring
• Connect element and stand-off tube with clamp and lock pin
• Push Taper-Lok flange onto the tube flange and hot bolt
• Remove support rods
• Tighten bolts, using star pattern, to proper torque
35

37. Element Loading
36

38. Element & Taper-Lok Stand-off Tube Connection
Membrane connected to Taper Lok
flange with permeate tube
Do not forget the
metal seal ring!
37

39. Loading Procedure – Final Steps
• Repeat procedure at next membrane tube until all tubes are
loaded
• Purge skid with nitrogen and maintain nitrogen blanket
38

40. Nitrogen Purge
• Nitrogen Purge and blanket all installed membrane
elements when not in use
• Always purge after exposing element to air
• Always purge prior to opening the system for maintenance
- Remove hydrocarbons
- Purge to meet safety requirements (LEL – lower explosion
limits, etc.)
• Nitrogen is an asphyxiant – oxygen-deficient atmosphere
may result
• Never allow the permeate pressure to exceed the feed or
residual pressures
39

41. • Pre-treatment & Membrane
skid/modules must be leak tested
to operating pressure prior to
introducing feed gas to the system
• This procedure must be followed
prior to the initial startup, after
turnaround or after opening up
significant components for
maintenance purposes
• If the unit is not to be started
immediately, leave a nitrogen
blanket until start-up
• Do not exceed 5 bar/minute
depressurization rate
• Always depressurize downstream
of filters (forward flow direction) to
avoid damage to cartridges
Leak Test
40

42. Leak Test Depressurization Procedure –
Membrane Section
• If using process gas:
- Must depressurize permeate and residual gas sides together always
keeping permeate pressure 3-5 bar lower
- Never depressurize via permeate side only
- Never allow permeate pressure to exceed feed or residual gas
pressure
41
Very important to always keep permeate pressure lower. Process gas
must be depressurized from both sides to avoid liquids condensation
and subsequent damage to membrane elements

43. Residue Gas Compressor (Not in UOPR Scope)
• Compresses residue gas to pipeline pressure
• Two centrifugal compressors running in parallel
- Not intended to be ran at the same time
• Online Condition Monitoring
- Continuous Vibration Monitoring
- Temperatures
 Gas (suction/discharge)
 Lube Oil
- Oil Sampling
• Preventative Maintenance
- Filter Changes (per dP monitoring or periodically based on
IOM)
 Lube Oil
 Seal gas
- Oil Conditioning (based on oil analysis)
- Check manual for all recommended PM tasks
42

44. © 2017 UOP LLC. A Honeywell Company All rights reserved.
Start-Up/Shutdown
Separex™ Membrane System
 PV Gas Ca Mau GPP Project

45. • Main Steps for Start-Up:
- PRETREATMENT START-UP
 Pressurization
 Warm-Up
- INITIAL MEMBRANE BANK START-UP
 Assure Initial Membrane Bank is Ready
 Pressurize Membrane Bank
 Warm-Up Membrane Bank
 Permeate Pressure Reduction
- START-UP ADDITIONAL MEMBRANE BANK
 Pressurize Membrane Bank
 Warming-Up Membrane Bank
 Permeate Pressure Reduction
Start-Up Steps – Overview
44

46. 1. All blinds are in positions shown per P&ID’s.
2. All pressure relief devices are online, tested and installed. Any isolation valves
must be locked open or car sealed open (CSO).
3. The utilities, sewers, and flare header are purged and in service.
4. All instruments (sensors, controllers, etc.) are calibrated and commissioned
5. All drains and vent valves to atmosphere are closed, plugged, or blinded.
6. The proper quantity and quality of nitrogen is available.
7. All equipment and associated piping is air-freed by purge with nitrogen.
8. All nitrogen isolation valves closed and bleed valves open.
9. All manual vent valves to the relief header are closed.
10. All process valves for on-line sample points are lined up for service.
11. All process root valves for Pressure and Pressure Differential instruments
(indicators, switches, and transmitters) are lined up for service.
12. Feed Gas and Residual Gas Shut down valves (SDVs) are closed.
13. All blowdown valve (BDVs) are closed.
14. Verify that all membrane bank isolation and startup valves are closed.
GENERAL PRE-STARTUP CHECKLIST
45

47. Step Location Description Chk
1 CCR Verify Plant Emergency Shutdowns have been RESET
2 CCR Confirm adequate feed gas pressure (~54 bar(g)) and flow (2.04 lean/.95
rich mmscmd to membranes) is available for start-up at upstream unit.
3 CCR Close and confirm closed the following automated valves:
 Shutdown Valves: 4090, 4094 and 4095
 Permeate Pressure control valve
 Close membrane bypass valve
4 Field Confirm all manual valves per checklist (to be determined) are closed prior
to start-up.
5 Field
Field
Position one operator at the 2” Pressurization by-pass valve L1D1 1600.
He/she will have to slowly open the valve in order to pressurize this
section.
Another operator should be positioned at PI 4091 to supervise
pressurization of the pre-treatment section.
6 Field Slowly open 2” Pressurization by-pass valve L1D1 1600.
Pressurization rate should be no higher than 3.5 bar/minute.
CAUTION: To prevent damage to filter coalescer and other downstream
equipment, the pressurization rate must not exceed 3.5 bar/minute.
7
CCR
Field
When the pre-treatment section pressure reaches approximately operating
pressure, pressurization is complete.
Therefore:
Open 10” Pre-treatment section isolation valve SDV4090.
And then,
Close 2” Pressurization by-pass valve L1D1 1600 once SDV4090 is fully
opened.
8 Field Drain any liquids in feed gas at Filter Coalescer manual drain valves.
CAUTION: Membrane elements can suffer permanent damage from
contact with liquids.
9
Field
Field
CCR
After pressurization is complete, the next step is to adjust the inlet gas
temperature to meet the target.
Therefore,
Open 2” Pre-treatment warm-up isolation valve G1D1 1212.
And then,
Slowly Open 2” Pre-treatment warm-up valve and L1D1 1617. Adjust it to
achieve a desired feed flow of: 30% of the design flowrate.
Request flow rate confirmation from CCR at upstream unit flow meter.
10 CCR When the pre-treatment section temperature reaches target temperature
per heat and weight balance at TI 4003B the temperature adjustment step
is complete.
Pre-treatment Section Start-up
46

48. Step Location Description
1
CCR
CCR
Field
Field
Field
In order to start-up the Membrane section, Confirm it is depressurized – Check the following pressure instruments
indication:
 PI-4411B – Bank 1 Permeate Line
 PI-4411A – Bank 1 Residue Line
 PT-4094 –Permeate Line
 PT-4095 –Residue Line
If Membrane section is not fully depressurized, open 2” Permeate start-up valve B1D1 2433 and 2” Permeate
start-up isolation valve L1D1 2612.
Allow to depressurize for a few minutes. After confirmation, close B1D1 2433 and L1D1 2612.
CAUTION:
Membranes kept under a nitrogen blanket will have equal residual and permeate pressures. If depressuring
manually always open the permeate startup valve FIRST. Inadvertent opening of the residual startup valve can
cause a reverse pressurization where the permeate pressure will become higher than the residual. This can cause
permanent damage to the membranes. Check valves at the end of each membrane element string are intended to
avoid damage, but they should not be relied upon.
When Membrane Section prsure is fully depressurized, start-up may proceed.
2 Field Confirm all manual valves per Appendix A are closed prior to start-up.
3
Field
Field
Field
Field
Field
Prior to start, Open the following valves:
- 6” Bank 1 feed isolation valve B1D1 2409.
- 2” Bank 1 permeate isolation valve L1D1 2612.
- 2” Bank 1 residue isolation valve L1D1 2611.
After that,
Slowly open 2” Membrane 1 feed by-pass valve L1D1 2604 and maintain a pressurization rate of 3.5 bar/minute to
pressurize Membrane 1.
Operator to monitor the pressurization rate at PI 4411B (Membrane 1 permeate line) and PT-4411A (Membrane 1
residue line).
4 CCR
Field
Field
CCR
When permeate pressure PI4411B is ~ 5 bar(g), crack OPEN - 2” Permeate start-up valve B1D1 2433.
Adjust the 2” Permeate start-up valve B1D1 2433 to ALWAYS maintain permeate pressure lower than residual by
5 bar†.
Operator to monitor residue pressure at PI 4411A.
Operator to monitor permeate pressure at PI 4411B.
† - CAUTION: Allowing permeate pressure to approach or exceed residue pressure can damage the membranes.
Always maintain permeate pressure 5 bar lower than residual throughout the procedure. An operator should be
stationed at the 2” Permeate start-up valve B1D1 2433 at all times.
An excessive rate of pressurization or depressurization higher than 3.5 bar/minute can also damage the
membranes. These events can occur if the residue start-up valve is opened too quickly.
The above two warnings apply throughout the remainder of the procedure.
MEMBRANE BANK STARTUP
47

49. Step Location Description
5 CCR
Field
Field
CCR
When residue pressure PI 4411A is approximately 13-15 bar(g), crack-open 2” Residue
start-up valve B1D1 2432 to establish some flow through the membranes.
Adjust 2” Permeate start-up valve B1D1 2433 to maintain a pressure difference
between residue and permeate pressures (PI 4411A – PI 4411B) of ~ 5 bar.
6 CCR
Field
Field
Keep the pressurization rate at 3.5 bar/minute. Bank 1 is fully pressurized when feed
pressure minus residue pressure is less than 3 bar (PI 4411A – PI 4411B < 3 bar).
Then:
Open 6” Bank 1 feed valve B1D1 2408.
After that,
Close 2” Bank 1 feed by-pass valve L1D1 2604 once B1D1 2408 is fully opened.
7 Field
Field
Further open 2” Residue start-up valve B1D1 2432 while maintaining permeate 5 bar
lower until target gas flow is achieved:
At Pre-treatment Section, gradually close the 2” Pre-treatment warm-up valve L1D1
1617 to allow the required flow through the Membrane Section and out the residual
startup line.
8
CCR
CCR
Monitor temperature difference between:
TI-4003A (Membrane Feed)
and
TI-4411 (Bank 1 Residual Gas).
When temperature difference (TI-4403A – TI-4411) is within 10ºC, then Membrane 1 is
warmed-up.
9 CCR
CCR
CCR
Contact Control Room prior to line-up the residue gas to downstream unit. Slowly open
B1D1 2422 and B1D1 2423.
After confirmation,
Slowly open 2” pressurization valve on residue header L1D1 2613. Monitor pressure till
both sides of the valve has equalized.
Open Shutdown valve SDV4095.
MEMBRANE BANK STARTUP
48

50. MEMBRANE BANK STARTUP
Step Location Description
10 Field
Field
Slowly close 2” Residue start-up valve L1D1 2611 ensuring feed gas flow is not reduced.
After that, close 2” Residue startup isolation valve B1D1 2432 once L1D1 2611 is fully
closed.
11 Field
Field
At Pre-treatment Section, completely close the 2” Pre-treatment warm-up valve L1D1
1617
Then, close the 2” Pre-treatment warm-up isolation valve G1D1 1212.
12 Field After lining-up the residue to downstream unit, it is time to reduce the permeate pressure.
Open B1D1 2424 and B1D1 2425.
Therefore, further open 2” Permeate start-up valve B1D1 2433 to reduce pressure at a
rate of 3.5 bar/minute. Continue to open the valve until the target permeate pressure is
observed at PI 4411B.
Warning – If for any reason the Membrane feed flow rate falls below minimum flow rate
while permeate pressure is being reduced, then stop depressurization and increase
permeate pressure.
13 Field
Field
Open 8” Permeate valve SDV 4094. Keep PCV 4094A and PCV 4094B closed. Slowly
start to open the PCV with small increments.
IN CONJUNCTION
Slowly close 2” Permeate start-up valve B1D1 2433 while maintaining the desired
permeate pressure on PI 4411B. Then, close 2” Permeate start-up isolation valve L1D1
2612 once B1D1 2433 is fully closed.
14 CCR After the unit is started-up, switch TIC-4003B Setpoint to the required feed membrane
temperature.
49

51. MEMBRANE BANK SHUTDOWN
Step Location Description
1 Field
CCR
Field
Prior to shut down of the Separex™ Membrane Skid,
station an operator at:
2” Permeate vent valve B1D1 2433 and 2” L1D1 2612
Also,
Station an operator at 6” D-4411 Bank feed valve
B1D1 2408 if D-4411 Bank is to be taken off-line.
2
Field
If one membrane skid is to be closed, adjust FCV
4092 accordingly to divert some flow from membranes
to the bypass line. Reduce the total feed to no more
than can be handled by the numbers of sections to be
used.
Close the valves below:
6” B1D1 2408 (Feed)
6” B1D1 2423 (Residue)
Open:
2” B1D1 2612 permeate vent valve
Partially open:
2” B1D1 2433 permeate vent valve
Close:
6” B1D1 2425 (Permeate)
Open:
2” L1D1 2611 residue vent valve but keep closed 2”
B1D1 2432.
50

52. MEMBRANE BANK SHUTDOWN
Step Location Description
3
Field
CCR
Field
Crack Open:
2” residue vent valve to reduce residual pressure at 3.5 to 5 bar(g) per
minute.
Operator to monitor residue PI 4411A if Bank 1 is to be taken off.
Do not open the residual vent valve so far that the residual pressure
drops to near the permeate pressure. The residual pressure must always
be at least 7 bar(g) higher than the permeate pressure until the end of
depressurization.
CAUTION: An excessive rate of depressurization higher than 3.5 to 5
bar/minute can also damage the membranes. These events can occur if
the residue start-up valve is opened too quickly.
4 CCR
Field
CCR
Field
Field
Field
Field
When the residue PI 4411A reaches a pressure of ~7 bar(g)
Open further 2” permeate vent valve B1D1 2433 and allow the residue to
depressurize through it.
When the residue pressure PI 4411A drops to below 1 bar (g) seen at
pressure PI 4411B, Close:
2” Residue vent start-up valve L1D1 2611.
2” Residue start-up isolation vent valve B1D1 2432
2” Permeate start up vent isolation valve L1D1 2612
2” Permeate start-up vent isolation valve B1D1 2433
5 After depressurization is complete, purge and add nitrogen blanket if the
membrane section is to be offline for more than an hour.
51

53. © 2017 UOP LLC. A Honeywell Company All rights reserved.
Normal Operations and Troubleshooting
Separex™ Membrane System
 PV Gas Ca Mau GPP Project

54. Membrane Mechanical Damage
• Reverse Pressure Differential
- Occurs when Permeate Pressure > Feed or Residual Pressure
- Membrane cracks at adhesive lines
- Most likely to occur on shutdown or purging
- Indicated by increased H/C losses to permeate
- Be aware of system conditions at all times
53

55. Membrane Mechanical Damage (continued)
• High Flow per Operating Area (# tubes online)
- On startup or at changes in system capacity
- During system upsets
- Also may be caused by flow surge
- Elements can ‘telescope’ and damaged
- Indicated by increased Hydrocarbon losses to permeate
54

56. Membrane Mechanical Damage (continued)
• Rapid Depressurization
- Occurs when banks or skid depressurizing valves opened too
quickly
- Depressurization is a manual operation
- When depressurizing individual bank, use ~15 minute criteria
for depressurizing.
- Crack open valve initially and then open more as pressure
decreases (< 5bar/minute)
55

57. Membrane Contaminant Damage
• Liquids
- Chemical injection such as methanol
- Upstream unit malfunction
- Filter Coalescer malfunction
- Poor commissioning
- Feed temperature control failure
• Particulate Damage
- Occurs when particle filter malfunctions
- Usually due to operator inattention
- Particles of corrosion products or activated carbon fines clog the
membrane elements
- May result in high HC losses
56

58. Hydrocarbon Dew Point
• Condensation within the
membrane will damage it’s
elements
• Residual stream temperature
must always be 5C above the
calculated dew point (dew point
margin) to guard against
condensation
• Factors affecting dew point
- Permeate pressure
- Number of membrane
sections
- Membrane feed temperature
• There is no major concern due
to cryo unit residue gas dew
point being low
57
T
J-T effect
HC Dewpoint
HC DEWPOINT
MARGIN

59. Membrane Mechanical Damage
58

60. System Optimization
• Goals
- Target Export Gas CO2 specifications
- Maximize sales gas production
- Minimize hydrocarbon losses
- Maximize membrane life
• Why optimize?
- Too low residue gas CO2 = more hydrocarbon losses
 Higher CO2 removal = higher CO2 and methane slippage
- Too high membrane feed gas temperature = more hydrocarbon losses
- Too high permeate pressure = more hydrocarbon losses
- Too high residue gas CO2 = off-spec HHV
59

61. Membrane Optimization
• Methods
- Operating Condition Adjustments
 Feed flow
 Lowest feed temperature
 Feed pressure (to a more limited extent)
 Lowest permeate pressure
- Membrane Area Adjustment
• Lean Case
- The Normal LEAN case requires all 4 banks in
operation, while the Normal RICH case requires only
one bank in operation
- Load 10 elements per tube (5 on each side)
60

62. Operations Adjustment
Control Variables
• A: Number Banks Online (Membrane Area)
• T: Feed Temperature (A-3001 outlet)
• P1: Feed Pressure (discharge of compressor, indirect
control)
• P2: Permeate Pressure
• F: Feed Flow (to an extent, indirect control)
• F1: Bypass
P1
F FEED
RESIDUAL GAS
T P2A
PERMEATE
F1
61

63. Membrane Operating Variables
Process Variable
Effect on Residual Composition
(with fixed membrane area)
Increased Feed Flowrate Higher CO2 content
Decreased Feed Flowrate Lower CO2 content
Increased Membrane Feed Temperature Lower CO2 content
Decreased Membrane Feed Temperature Higher CO2 content
Increased Feed Pressure Lower CO2 content
Decreased Feed Pressure Higher CO2 content
Increased Permeate Pressure Higher CO2 content
Decreased Permeate Pressure Lower CO2 content
Increased Feed CO2 Content Higher CO2 content
Decreased Feed CO2 Content Lower CO2 content
62

64. Membrane Operating Conditions
FEED FLOW
• An Increase in Feed Gas Flow results in:
- Increase of CO2 Content of Residual/Sales Gas
- Can cause mechanical damage to membrane if above design or
too little area for the feed rate
• A Decrease in Feed Gas Flow results in:
- Reduction of CO2 Content in Residual/Sales Gas
- Higher hydrocarbon losses
- Can potentially cause hydrocarbon condensation and membrane
damage if flow or operating temperature is too low
 Not expected to be a major issue here since dew point of gas is
already low to the membrane unit
63

65. Membrane Operating Conditions (continued)
TEMPERATURE
• An Increase in Operating Temperature results in:
- Reduction of CO2 Content of Residual/Sales Gas
- Increase of permeate flow (higher hydrocarbon losses)
• A Decrease in Operating Temperature results in:
- Increase in CO2 Content of Residual/Sales Gas
- Reduction of permeate flow (lower hydrocarbon losses)
- Can cause hydrocarbon condensation and membrane damage if operating
temperature is too low
64

66. FEED PRESSURE
• An Increase in Operating Pressure results in:
- Reduction of CO2 Content of Residual/Sales Gas
- Increase of permeate flow (higher hydrocarbon losses)
• A Decrease in Operating Pressure results in:
- Increase in CO2 Content of Residual/Sales Gas
- Reduction of permeate flow (lower hydrocarbon losses)
Membrane Operating Conditions (continued)
65

67. PERMEATE PRESSURE
• An Increase in Permeate Pressure results in:
- Increase in CO2 Content of Residual/Sales Gas
- Reduction of permeate flow
• A Decrease in Permeate Pressure results in:
- Reduction of CO2 Content of Residual/Sales Gas
- Increase of permeate flow
- Typically improves selectivity – decreases hydrocarbon concentration
in permeate
Membrane Operating Conditions (continued)
66

68. Membrane Operating Conditions (continued)
MEMBRANE AREA
• An Increase in Membrane Area results in:
- Reduction of CO2 Content of Residual/Sales Gas
- Increase of permeate flow (higher hydrocarbon losses)
• A Decrease in Primary Membrane Area results in:
- Increase of CO2 Content of Residual/Sales Gas
- Reduction of permeate flow (lower hydrocarbon losses)
67
Can only be increased in increments.
Do not operate below minimum or above maximum flow for the # of
membrane tubes online

69. Optimization Flow Chart
Plant Operation
Stable
CO2 in
Sales Gas at
at 8%?
Plant is
operating in
Specification
Sales CO2
Concentration?
Do one of the
following:
2) Increase
Permeate
backpressure
3) Increase feed
gas flow
Shut down a
membrane bank
Do one of the
following:
3) Decrease feed
gas flow
Below 8% Above 8%
Yes
2) Increase
feed gas
temperature
1) Decrease
feed gas
temperature
Can 1 bank be
Taken off-line?
No
Yes Yes
No
Can 1 bank be
Be put on-line?
Start up a
membrane bank
No
In order of preference In order of preference
1) Decrease
permeate
pressure
68

70. Filter Coalescer
69
Filter Coalescer
Primary Symptom Local Causes Remedy
Liquid carryover Filter Coalescer cartridge rupture
High delta P (then low dP)
Feed surge
Pressure surge
Filter Coalescer cartridge plugged
High delta P
High solids ingress
Bypass the whole
unit for filter
cartridge
replacement if
possible, replace
cartridges
High level in Filter Coalescer due to:
Excessive liquids load
Plugged LCV
Level instrument malfunction
Troubleshoot
upstream unit
Isolate & clean
LCV
Repair instrument
malfunction
Follow specific recommendations from coalescer vendor

71. Membrane Unit
Membrane Unit
Symptom Local Causes Remedy
Low feed temperature to
membranes
Residue Gas Cooler or
upstream issues
Troubleshoot Residue Gas
Cooler or upstream issues
High feed temperature
to Membranes
Residue Gas Cooler or
upstream issues
Troubleshoot Residue Gas
Cooler or upstream issues
High CO2 content in
residual gas
Permeate pressure set too
high
Lower permeate pressure
set point
Increased feed gas flow rate
or CO2 composition
Lower permeate pressure.
Raise Membrane Feed
Temperature
Start additional membrane
bank/section/skid
Damaged membranes due to
condensation, or aging; or
feed gas flow or composition
too high for design.
Add, and/or replace
elements in tubes
Reduce feed gas flow or
CO2 level
70

72. Membrane Unit
Membranes Unit
Symptom Local Causes Remedy
Low CO2 content in
residual gas/ poor
hydrocarbon recovery
Permeate pressure set too
low
Raise permeate pressure
control set point,
investigate downstream
compression
Decrease in feed flow rate
or composition (low CO2)
1. Raise permeate
pressure
2. Lower Membrane
Feed Temperature
3. Remove membranes
sections
Feed flow rate and/or
composition too low,
outside of design range
1. Increase feed gas flow
2. Remove membrane
sections or elements
per tube
Feed pressure too high 1. Decrease feed gas
pressure
2. Remove membrane
sections
71

73. Membrane Unit
Membranes Unit
Symptom Local Causes Remedy
Decrease in permeate CO2
concentration, increase in
hydrocarbon concentration
Elements are damaged and
leaking
Find tube with leaking
element by performing
thermal scan.
Replace elements at
cold tubes
72

74. Damaged Element – Visual Inspections
73
New Membrane element

75. Thermal Scanning
• Quickly identify tubes with potential damaged elements based
on permeate tube temperatures
• Use thermal IR gun or similar
• Aim directly onto the permeate pipe exiting each membrane
tube
- Do not scan on pipe insulation
• Scan similar position for all permeate pipes
- Suggestion: complete at night – minimize impact of sunlight
• Can also be completed on the residual gas exit nozzles
• Record:
- Temperature
- Skid/tube number/permeate or residual
- Populate data into the excel sheet
74

76. Thermal Scanning
• Tubes should have similar permeate temperatures
• Tubes with severely leaking/damaged elements should show
colder permeate temperature
- More flow from high pressure to low pressure Joule Thompson
effect
• Statistics/data graphs can help identify which tubes may have
leaking elements
75

77. Good Thermal Scan Data
• All permeate tubes: similar temperature
- Not a lot of scatter in the data: data points all between 47-48C
76
40
41
42
43
44
45
46
47
48
49
1 3 5 7 9 11 13 15
PermeateTemperature,DegC.
Tube

78. Suspected Tube with Leak- Thermal Scan Data
• One tube temperature significantly different than the others
77
38.0
38.5
39.0
39.5
40.0
40.5
41.0
41.5
42.0
42.5
43.0
43.5
1 3 5 7 9 11 13 15
PermeateTemperature,DegC.
Tube
Tube with potential leaking/damaged element

79. 78
UOP 7116-78