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Hydrocarbon Dew Point Control - Gas Processing · PDF fileHydrocarbon Dew Point Control A.03...

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Australia Process Group Pty Ltd 5 Hobbs Court, Rowville, (Melbourne), VIC 3178, Australia. Phone: +61 3 9212 7100 Fax: +61 3 9212 7199 E-mail: [email protected] Web: www.processgroup.com.au Singapore Process Group Pte Ltd 298 Tiong Bahru Road,#12-02/03 Central Plaza, Singapore 168730 Phone: +65 6276 8349 Fax: +65 6274 2005 E-mail: [email protected] Web: www.processgroup.com.sg Middle East Process Group International Ltd P.O. Box 46153, Abu Dhabi, UAE. Phone: +971 2 5500 899 Fax: +971 2 5500898 E-mail: [email protected] Web: www.processgroupintl.com Hydrocarbon Dew Point Control A.03 Introduction Hydrocarbon Dew Point Control Units (DPCUs) are designed to inhibit the formation of solid hydrates in gas streams and by default they perform a level of dehydration. This is achieved through the injection of a liquid Hydrate Inhibitor directly into the gas stream. The Hydrate Inhibitor is selected based on low viscosity and low freezing temperature rather than dehydration ability. There are 2 common types of liquid Hydrate Inhibitor used for Dew Point Depression: Mono-Ethylene Glycol (MEG) Methanol (MeOH) The type of Hydrate Inhibitor used and the package design depends on several factors, and the end-users specific require- ments and objectives for the gas stream being processed. Each package is typically designed in close consultation with the client to ensure the best overall design is achieved. Design Basis The design of a DPCU follows a basic structure. However, there are a number of approaches to achieve the end means – Hydrocarbon Dew Point Depression. Each system is typically designed and built as a complete turn- key package with particular emphasis given to the following issues: Discharge gas hydrocarbon dew point, Discharge gas water dew point, Minimum inhibitor losses, Minimum power consumption, Optimum plant efficiency & design integrity, Compliance with HSE requirements, Environmentally conscientious design. The resulting design will be influenced by all of these factors, and the emphasis & importance given to each particular issue. Photograph: MEG DPCU (155TJ/day) package for Blacktip Project, N.T. Australia. Rev 11/2012 Represented by:
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Page 1: Hydrocarbon Dew Point Control - Gas Processing · PDF fileHydrocarbon Dew Point Control A.03 Process Description In a typical MEG Injection Dew Point Control Unit (DPCU), the gas is

AustraliaProcess Group Pty Ltd

5 Hobbs Court, Rowville, (Melbourne), VIC 3178, Australia.Phone: +61 3 9212 7100 Fax: +61 3 9212 7199

E-mail: [email protected] Web: www.processgroup.com.au

Singapore Process Group Pte Ltd

298 Tiong Bahru Road,#12-02/03 Central Plaza, Singapore 168730Phone: +65 6276 8349 Fax: +65 6274 2005

E-mail: [email protected] Web: www.processgroup.com.sg

Middle EastProcess Group International Ltd

P.O. Box 46153, Abu Dhabi, UAE.Phone: +971 2 5500 899 Fax: +971 2 5500898

E-mail: [email protected] Web: www.processgroupintl.com

Hydrocarbon Dew Point ControlA.03

Introduction

Hydrocarbon Dew Point Control Units (DPCUs) are designed to inhibit the formation of solid hydrates in gas streams and by default they perform a level of dehydration. This is achieved through the injection of a liquid Hydrate Inhibitor directly into the gas stream. The Hydrate Inhibitor is selected based on low viscosity and low freezing temperature rather than dehydration ability.

There are 2 common types of liquid Hydrate Inhibitor used for Dew Point Depression:

• Mono-EthyleneGlycol(MEG)• Methanol(MeOH)

The type of Hydrate Inhibitor used and the package design dependsonseveralfactors,andtheend-usersspecificrequire-ments and objectives for the gas stream being processed. Eachpackageistypicallydesignedincloseconsultationwiththe client to ensure the best overall design is achieved.

Design Basis

The design of a DPCU follows a basic structure. However, there are a number of approaches to achieve the end means – Hydrocarbon Dew Point Depression.

Eachsystemistypicallydesignedandbuiltasacompleteturn-key package with particular emphasis given to the following issues:

• Dischargegashydrocarbondewpoint,• Dischargegaswaterdewpoint,• Minimuminhibitorlosses,• Minimumpowerconsumption,• Optimumplantefficiency&designintegrity,• CompliancewithHSErequirements,• Environmentallyconscientiousdesign.

The resulting design will be influenced by all of these factors, andtheemphasis&importancegiventoeachparticularissue.

Photograph:MEGDPCU(155TJ/day)package for Blacktip Project, N.T. Australia.

Rev11/2012

Represented by:

Page 2: Hydrocarbon Dew Point Control - Gas Processing · PDF fileHydrocarbon Dew Point Control A.03 Process Description In a typical MEG Injection Dew Point Control Unit (DPCU), the gas is

Hydrocarbon Dew Point Control

A.03

Process Description

InatypicalMEGInjectionDewPointControlUnit(DPCU),thegasisfirstpassedthroughanInletSeparator(1)whereanyfreeliquidsareremoved.

Justpriortoenteringthegas/gasexchangerpressurisedLeanMEGisinjectedintothegasstream(2).AdditionalMEGisinjectedandtheMEG-gasmixtureisthenfurthercooledthrougheitherExpansion(Joule-ThompsonValve/Orifice)orRefrigeration(3).

Thefurthercoolingcondensesanyresidualwaterand/orhydrocarbons.ALowTemperatureSeparator(LTS)(4) is located downstream to remove any free liquids – now including the condensed water, condensed hy-drocarbonsandinjectedMEG.Thecooledgaswithadepresseddewpointiscirculatedbackintothegas/gasexchangerforpre-coolingoftheinletgas(2).

TheLTSisgenerallya3-PhaseSeparatorwhichallowsthe effective separation of not only the gas from the liquids, but also the aqueous and hydrocarbon liquid phases from one another.

Theaqueousphase,containingthewaterandMEGisroutedtotheMEGRegenerationPackagewherethewa-terisdrivenofftoproduceLeanMEG.Theliquidhydro-carbonphaseisusuallymixedwiththeliquidsfromanyinlet separation and either routed to storage or further processinginaCondensateStabilisationPackage.

© Process Group Pty Ltd, 2008 – 2012.

(OPTIONAL)

CONDENSATE STABILISATION UNIT

Hydrocarbon Dew Point Control Unit

OUTLET GAS

INLET GAS1

MEG REGENERATION PACKAGE

EXPANSION2

6

REFRIGERATION

3

5

4


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