sulzer chemtech moving ahead - ntnufolk.ntnu.no/skoge/prost/proceedings/distillation10/da2010...

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


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


Mechanisms of droplet collection

Obstacle

e.g. Fiber

FLOWVelocity (V)

< 0.5 µm

> 100 µm

> 3 µm

~ 1 µm

Sulzer Chemtech


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


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


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


Separation equipment – Application

Sulzer KnitMesh™

mist eliminatorsSulzer Mellachevron™

vane packs

Shell Swirltube™

axial cyclones

VANE MIST ELIMINATORS

Sulzer Chemtech


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


Internals

Sulzer Chemtech


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


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


Case Study : TEG Contactor, New Zealand

Sulzer Chemtech


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


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


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

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Operating conditions far away from

design

Factor > 70 higher !!

Factor ~ 7 higher !!

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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

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What could be happening

Liquid entrainment is much higherhigh levels of liquid HC in chimney trayfoamingTEG dissolution and carry-down intocolumn sump

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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)

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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


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


Thank you for your attention !

Sulzer Chemtech

– Moving Ahead

sulzer chemtech moving ahead - ntnufolk.ntnu.no/skoge/prost/proceedings/distillation10/da2010...

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