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Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Separation devices for the gas industry : TEG contactor case study, New ZealandAbhilash Menon , Patrick Lura & Gert Konijn§
Sulzer Chemtech
– Moving Ahead
Sulzer Chemtech, Winterthur, Switzerland§ Shell Global Solutions International, Amsterdam, the Netherlands
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Outline
Mist elimination technology in G/L separation
fundamentals
typical mist elimination devices
Applications in NG dehydration
Case study : TEG contactor, New Zealand
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Mechanisms of droplet collection
Obstacle
e.g. Fiber
FLOWVelocity (V)
< 0.5 µm
> 100 µm
> 3 µm
~ 1 µm
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Wire mesh mist eliminators
moderate gas handling and liquid
load capacity
very high separation efficiencies
prone to fouling with high liq load
low pressure dropGas with free liquid
Gas without free liquid
by gravity by gravity
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Vane-pack mist eliminator
Horizontal gas flowVertical gas flow
Gas
Gas droplet inertia, centrifugal
force, impingement, g
high gas handling
and liquid load capacity
high separation efficiency
suitable for high viscosity
low pressure drop
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Primary gas outlet
Secondary outlets
(from slits)
Swirl part
Separation part
Secondary gas
Liquids
Bottom plate
Top plate
Separation swirltube
inertial, centrifugal force, g
very high gas handling and liquid
load capacity
high separation efficiency
prone to fouling with high viscosity
moderate pressure drop
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Separation equipment – Application
Sulzer KnitMesh™
mist eliminatorsSulzer Mellachevron™
vane packs
Shell Swirltube™
axial cyclones
VANE MIST ELIMINATORS
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Natural Gas Dehydration
Flash
Tank
Glycol Filter
Glycol
Cooler Heat
Exch.
Storage Tank
Stripping column
Heater
Heater
Heat Exchange
Section
Rectification
section
Condenser
Water vapors +
Hydrocarbon gas
Regenerator
Stripping
Gas
Lean TEG
Wet Gas
Dehydrated
Gas
Rich TEG
Water +
Condensate
Contactor
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Internals
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Original DesignBubble Cap trays and
KnitMesh mist eliminator
100 % capacity
1.5 F-Factor
190 % capacity
>20 % more efficiency
2.9 F-Factor
First Revamp
Mellapak™ and
KnitMesh mist eliminator
TEG
NG
400 % capacity
20 % more efficiency
6.0 F-Factor
Third Revamp
Shell Swirl Tube™Trays
TEG
NG
Glycol Contactor - Revamps
Second Revamp
MellapakPlus™ &
Swirldeck ™
TEG
NG
300 % capacity
>20 % more efficiency
Max. 4.5 F-Factor
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Glycol losses
Glycol losses with a secondary demisting device well selected according to the gas loads
0
0.015
0.030
0.045
0.060
0.075
0.090
0.105
0.110
0.125
0.140
0.155
0.170
0.185
0.200
0.215
0.230
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
F-Factor
Mellapak
MellapakPlus
Bubble Cap Trays
US
ga
l/M
Ms
cf
0.1 USgal/MMscf
Swirl-tube trays
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Case Study : TEG Contactor, New Zealand
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
TEG Contactor
first supplied by Sulzer in 2005column brought online in Oct.2006
top de-entrainment device: Knitmesh 9797 mesh pad
top Liquid distributor
packing : Mellapak structured packing
chimney tray collector
integral scrubber: rectangular vertical vane-pack (non-Sulzer hardware)
inlet device: Schoepentoeter
Vane pack
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Reported Problems
Problemexcessive glycol losses > 20 times expected losses even at 60% throughput. 3% of overall TEG to column was lost
required glycol losses: 13.4 litres (TEG)/MMscm (gas)Sulzer guarantee (with Knitmesh 9797 mesh pad): 6.7 litres/ MMscm
Information received• lost glycol traced to the column sump• samples taken downstream of the TEG Contactor gas outlet showed little
presence of TEG• dewpoint specifications met• pressure drop across packing: 0.8 to 1.2 kPa so foaming in packing
unlikely cause of problems• no separate inlet separator upstream of TEG Contactor• prolonged skimming in chimney tray showed presence of HC liquid and
foam
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Actions
1st reaction
vane-pack wrongly installed or damaged ?
Course of action / Findings
Inspection carried out on column internals (Nov.’06)
No damage reported. Column is clean and internals
are correctly fitted. No damage to filter or gaskets,
etc
Chimney tray leak tested twice and confirmed to be
leak tight
Drainpipes from vane-pack extended to below liquid
level (this did not solve the problem)
Vane-pack detail
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Operating conditions far away from
design
Factor > 70 higher !!
Factor ~ 7 higher !!
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Possible reasons for high glycol losses
Vane-packs not advisable under such operating
conditions
high pressure : 66 barglow surface tension : gas easily entrains the HC liquidvery high liquid loads : far away from design
conditions separation efficiency for vane-packs (HC systems)
drastically reduces (< 90%) at high P
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
What could be happening
Liquid entrainment is much higherhigh levels of liquid HC in chimney trayfoamingTEG dissolution and carry-down intocolumn sump
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Findings
Significantly more free liquid HC was present in the feed
compared to original design conditions
Flow Parameter at contactor inlet based on new conditions = 0.014
Flow Parameter at the vane-pack based on new conditions = 0.002 (<< 0.01) (Assuming a schoepentoeter separation
efficiency of ~85%). thus high liquid loads cannot be the sole reason why the
vane-packs didn’t work well
Presence of an inlet gas cooler upstream of gas inlet
droplets created due to condensation (much smaller than those generated by shear forces)
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Proposed revamp
Replace vane-pack demister with :
pre-conditioner mist-mat :
Knitmesh 9797 modelhigh performance Swirl Tubes :
better g/l separation
Gas with fine
mist
Mesh pad
operates at
velocity beyond
re-entrainment
point
Most captured
mist is re-
entrained as
large droplets
Mist free gas
Mellachevron
capture large
droplets
Captured liquid
drains
No gap in some cases
Proposed changes for chimney tray:
few risers to be blinded off to minimize splashing of free liquid into the risers
all riser hats to protrude downwards to cover the riser opening
• Inlet device:− No change: existing Schoepentoeter to
be re-used
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Successful revamp
Nov.2006: decision to replace vane-pack by KM 9797 mist-
mat & Swirl-deck
Feb.2007: New separator installed. Installation supervised
by Sulzer
March 2007: Revamp has been successful
customer reports TEG losses problem solved entrainment from previously installed vane-pack section
significantly reduced and brought within spec limitsTEG losses reduced from 480 l/MMm3 to 6.7 l/MMm3
internal skim showed no condensate build up
no foaming observed
no TEG detected in column sump
Sulzer Chemtech
MeA, PERS 5, Nice / April 01-03, 2008
Thank you for your attention !
Sulzer Chemtech
– Moving Ahead
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