Lecture 14 LNG Alternatives R2 - Frederick Universitystaff.frederick.ac.cy/eng.ap/FALL2016/MOE506/Lecture … · · 2016-12-0505/12/2016 2 Energoil Consulting Compressed Natural

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Consulting

Liquefaction Processes

Lecture 14

LNG Alternatives

Slide 1© Dr. Richard J Barnes 2015

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Consulting


Compressed

Natural Gas


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ConsultingCompressed Natural Gas

• CNG avoids the expense of liquefaction, but does not achieve the same volume reduction.

• Limit of storage pressure is about 240 bar (3,600 psig).

• Reduction is about 1/240 compared with 1/600 for LNG.

• Storage developed to fit on conventional ships.


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ConsultingTrans Ocean CNG System

• Gas stored in FRP cylinders.

• Storage conditions of -40 °C and 240 barg.

• Cylinders installed in a standard ISO 40 ft. chilled container.

• Each container holds 315,000 SCF.


Source: http://www.transoceangas.com/containment_system-abs.jpg

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ConsultingVotrans System

• Gas stored in carbon steel pressure vessels.

• Storage conditions of -30 °C and 125 barg.

• Storage at low temperature results in a lower compressibility factor.


Source: http://www.enersea.com/images/stories/chart_gas_storage_optimization.jpg

Source: http://www.enersea.com/images/stories/header_costeffectivetechnology.jpg

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ConsultingCoselle System

• Gas stored in coiled 6” pipe.

• Each cassette is about 21 km (13 miles) long.

• The cassettes are permanently stored in a dedicated ship.

• Each cassette holds 4 million SCF of gas


Source: http://www.coselle.com/sites/default/files/pictures/content-pages/coselle-system.jpg

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Pipeline Natural

Gas


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Source: http://iis-db.stanford.edu/evnts/3917/jensen_slides_rev.pdf

Natural Gas Transport

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Gas To Liquids


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ConsultingWhat is GTL?

• GTL is Gas to Liquids conversion technology.

• Methane is converted to liquid hydrocarbons.

• Technology is potentially useful for transporting gas over long distances.

• Big research effort over the last 10 - 20 years.


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ConsultingWhy GTL?

• Large reserves of “stranded gas” in remote areas.

• LNG export requires large infrastructure at source and market, and specialist tankers.

• Gas export requires large investment in pipeline and compression.

• GTL offers method of exporting gas using conventional tankers.


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ConsultingGTL Fundamentals

• Converts natural gas to hydrocarbon liquids.

• Products: naphtha, kerosene, diesel & wax.

• Uses a three stage process:

– Syngas generation;

– Fischer-Tropsch reactor;

– Product work up.

• Product is high quality:

– No sulphur or aromatics.


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ConsultingHistory of F-T Development

• 1923 Process developed by Fischer and Tropsch.

• WW II to provide fuel for German forces.

• 1944 Production peaked at 16,000 BPD.

• 1955 Sasol build a plant in South Africa.

• 1982 Sasol build two more plants.

• 1993 South African build plant at Mossgas.

• 1993 Shell build the SMDS plant in Bintulu.

• 2006 Start up of Oryx GTL, Qatar.

• 2011 Shell ship first gasoil from Pearl GTL, Qatar.


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Consulting Simplified Process


GTL product

Hydrogen

Oxygen

Natural Gas

Steam

Air Air Separation

Primary Reformer

Secondary Reformer

FT Synthesis Reactor

Hydro-treater

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Syngas Generation


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Consulting Synthesis Gas Production

Air Separation

Primary (Steam)Reforming

SecondaryReforming

Carbon DioxideRemoval

Air

Nitrogen

Oxygen

NaturalGas

CarbonDioxide

RecycleGas

SynthesisGas


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ConsultingPrimary Reforming

• The primary reformer is a conventional steam/methane reformer.

• Steam and methane are fed over a catalyst at a temperature of 1,500 °F (816 °C).

• The reaction is endothermic.

• The catalyst is contained in vertical reformer tubes about 6” diameter and 45 ft. long.

• CO2 is recycled to improve the yield of H2.


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Consulting

• The reactions occurring in the reformer are:

CH4 + H2O � CO + 3H2

CH4 + CO2 � 2CO + 2H2

• The H2:CO ratio is typically >5.0.

• The target H2:CO ratio is 2 - 3:1.

© Dr. Richard J Barnes 2015 Slide 18

Primary Reformer Reactions

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ConsultingSecondary Reforming

• Objective is to make a syngas with a lower H2:CO ratio.

• Methane and oxygen are mixed with steam or CO2 and fed over a catalyst at an outlet temperature of 950 to 1100 °C (1740 to 2000 °F).

• The reaction is exothermic.

• Air can be used instead of oxygen, but dilutes the syngas with N2.


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• The reactions occurring with CO2 is:

2CH4 + O2 + CO2 � 3H2 + CO + H2O

When steam is used, the reaction is:

4CH4 + O2 + 2H2O � 10H2 + 4CO

• The H2:CO ratio is typically above 2.0.

• The actual H2:CO ratio can be adjusted by variation of the proportion of methane reformed in each reactor and quantities of CO2 and steam fed.

© Dr. Richard J Barnes 2015 Slide 20

Secondary Reformer Reactions

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Consulting


Fischer-Tropsch

Reactors


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ConsultingF-T Main Reactions

• Main reactions occurring in the F-T reactor are:

Alkenes: nCO + 2nH2 � (CH2)n + nH2O

Alkanes: nCO + (2n+1)H2 � H(CH2)nH + nH2O

Alcohols: nCO + 2nH2 � H(CH2)n OH + (n-1)H2O

Carbonyls: nCO + (2n-1)H2 � (CH2)nO + (n-1)H2O

Carboxylic acids (n>1):

nCO + (2n-2)H2 � (CH2)nO2 + (n-2)H2O

Water gas shift:

CO + H2O � CO2 + H2


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Consulting Synthesis (FT) Section

SynthesisUnits

Tail GasProcessing

AlcoholRecovery

Reaction WaterTreatment

Syngas

RecycleGas

TreatedWater

FuelAlcohols

Fuel GasMake Up

Syncrude ToRefining

LightEnds


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ConsultingF-T Reactor Operating Conditions

• Increased temperature favours less hydrogenated products (alkenes and oxygenates) and shorter chain products.

• Higher pressure favours oxygenates and chain growth.

• Increased space velocity reduces hydrogenation of oxygenates.

• Increased H2:CO increases hydrogenation.


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ConsultingFischer-Tropsch Reactors

• Four different configurations:

– Fixed

– Fluidised

– Fixed fluidised

– Slurry

• Process uses iron or cobalt based catalysts.

• Process is highly exothermic and requires large amount of cooling.


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ConsultingFischer-Tropsch Reactors


Source: http://www.platinummetalsreview.com/images/articles/55/4/Brown-august11-f2.jpg

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ConsultingOperational F-T Plants

Plant Location Feedstock Capacity, BPD Start Up

Sasol I, II and III

South Africa Coal 160,000 1955 onwards

Mossgas South Africa Natural Gas 23,000 1993

Shell SMDS Sarawak Natural Gas 12,500 1993

Exxon Louisiana Natural Gas 200 Operating “several years”

Syntroleum Washington, USA

Natural Gas 70 1999

Oryx Qatar Natural Gas 34,000 2006

Pearl (Shell) Qatar Natural Gas 140,000 GTL 120,000 Cond.

2011


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ConsultingMossgas Reactor

• Uses high temperature Fischer-Tropsch synthesis with an iron catalyst (Fe-HTFT) .

• Reactor design is circulating fluid bed.

• Operating temperature 330 – 360 °C.

• Operating pressure 2.5 M Pa (25 bar).

• Each reactor produces 8,000 BPD.


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ConsultingSMDS Bintulu

• Low temperature Fischer-Tropsch synthesis with a cobalt catalyst (Co-LTFT).

• Reactor design is multi-tubular fixed bed.

• Operating temperature 220 °C.


• Four reactors installed at Bintulu.

• Each reactor produces 3,000 BPD.

• Each reactor contains about 26,000 tubes.


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ConsultingPearl GTL Facility

• Scaled up version of Shell Bintulu.

• Two 70,000 BPD trains.

• Each train divided into four modular sections.

• Scale up factors:

– Air separation units, 1.13, one unit per train;

– Partial oxidation reformers, 3.5;

– Multitubular fixed bed F-T reactors, 1.12, six reactors per train.


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ConsultingOryx GTL Facility

• Designed for 34,000 BPD trains.

• Capacity initially limited due to catalyst fines clogging downstream equipment.

• Two slurry bed reactors, each 2,100 tons.

• Operating temperature 230 °C.


• Catalyst is Co/Pt/Al2O3 LTFT.


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Consulting


Product Work-up


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ConsultingProduct Work Up

• F-T product may require further processing dependent on:

– Upstream process (F-T reactor conditions);

– Product market.

• Hydrotreaters can be used to:

– Hydrogenate olefins to paraffins;

– Break long chain waxy hydrocarbons.


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ConsultingMossgas Refining

• F-T product processed with the NGL extracted from the feed gas.

• Light oil feed is distilled under slight vacuum.

• Products are gasoline, kerosene, diesel fuel and fuel oil.

Schematic overleaf after:

Arno de Klerk, Fischer-Tropsch Refining


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ConsultingMossgas Work Up


Fuel Oil

C4

Isomerisation

NaphthaHydrotreater

C5-C6

Hydroisomerisation

CatalyticReformer

DistillateHydrotreater

AliphaticAlkylation

AlkeneOligomerisation

Motor-Gasoline(Butane)

Motor-Gasoline(Alkylate)

Motor-Gasoline(Olefinic)

Motor-Gasoline(Isomerate)

Motor-Gasoline(Reformate)

Kerosene

Diesel Fuel

NGL C4s

C4 Condensate

C3 Condensate

C5+ Condensate

SLO

DO

NGLFuel Oil

NGL Naphtha

iC4 n-Butane

Alkylate

Naphtha

Distillate C5-C6 C5-C6

120-180 °C

C5-120 °C

NGL Distillate

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ConsultingAcronyms

• DO Decanted Oil

• NFL Natural Gas Liquids

• SLO Stabilised Light Oil


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ConsultingSMDS Bintulu Refining

• Only two processing units.

• Hydrocracker:

– Operates at 300 – 350 °C and 3 – 5 M Pa;

– Products are naphtha, kerosene and distillate.

• Hydrotreater products:

– C5 – C10 for solvents;

– C10 – C13 for detergents;

– C14 – C17 for flame retardant materials;

– Four wax fractions.Slide 37© Dr. Richard J Barnes 2015

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ConsultingBintulu Work Up


Wax Production

Fuel Gas

Naphtha

Kerosene

Distillate

Waxy Raffinate

C5-C10

Waxes

C10-C13

C14-C17

Waste Water

>C17

Waxy Raffinate

Hydrocracker

Hydrotreater

>C5

C1-C4

Wax

Aqueous Product

CO-LTFT Synthesis

Syngas

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ConsultingPearl Refining

• Product slate similar to Shell Bintulu.

• SMDS process produces final products and blending materials.

• Distillation only takes place after hydrocracking or hydrotreating to avoid boiling point broadening.

• Tight cuts between product carbon numbers.


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ConsultingOryx Refining

• Single hydrocracker conversion unit.

• Only produces intermediate products and LPG.

• Wax and cold condensate mixed to feed the hydrocracker.

• Hydrocracker operates at 350 °C and 7 M Pa.

• Products are naphtha, distillate and LPG.


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ConsultingOryx Work Up


LPG

NaphthaDistillate

Wax

ColdCondensate

Sulphiding

Agent H2 Purge

HydrocrackerStabiliserColumn

MainFractionator

Hot HPSeparator

Cold HPSeparator

Bottom Recycle>360 °C

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ConsultingF-T Product

• F-T products are totally free of:– Sulphur - Vanadium

– Nitrogen - Asphaltenes

– Nickel - Aromatics

• They also have few or no:– Cyclic hydrocarbons;

– Oxygenates.

• F-T products are high value for direct use or blending.


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ConsultingMain Technology Holders

• BP Amoco (UK and USA)

• Exxon (USA)

• Rentech (USA)

• Sasol (South Africa)

• Shell (UK and Netherlands)

• Syntroleum (USA)


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ConsultingEconomics of GTL

• Claimed to be economic against crude oil.

• Integration to use waste heat or tail gas.

• Generates large quantities of waste heat.

• Also produces large quantities of water.

• Technology offers opportunity to develop “stranded” gas.

• Contracting strategy more flexible than LNG.

• High quality GTL fuel attracts a premium.


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ConsultingSasol Mossgas

• Sasal GTL plant at Mossel Bay, South Africa.

Source: http://www.petroleum-economist.com/images/46/10195/LNGvsGTL_pic.gif


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ConsultingShell Bintulu

• Shell GTL plant in Bintulu, Malaysia.

• Plant was shutdown for two years after an explosion in the oxygen plant caused by ingress of smoke from forest fires.

Source: http://www.booklanddirect.com/images/BintuluPlant1-sm.jpg

Source: http://www.jgc.co.jp/en/02bisdmn/05cleanenergy_power/images/02-02-05-00-002-1.jpg


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ConsultingOryx, Qatar

• The Oryx plant experienced some teething problems, but is now running at full capacity.

• Problems from scale up and catalyst fines in the slurry F-T reactor.

Source: http://sasol.investoreports.com/sasol_review_2009/wp-content/uploads/2009/09/img_post-1.jpg

Source:http://images.pennnet.com/articles/ogj/thm/th_147575.jpg


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ConsultingShell Pearl, Qatar

• Start up in 2011.

• Much larger than Bintulu; 140,000 BPD compared with 12,500 BPD.

• It will has the world’s largest oxygen plant producing 20,000 tonnes/day.

Source:http://www.arcticgas.gov/sites/default/files/images/gtl-reactors.jpg

Source: http://www.shell.com/global/aboutshell/media/news-and-media-releases/2011/first-cargo-pearl-13062011/_jcr_content/par/textwithimage_3/image.114977828.jpeg


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ConsultingGTL Capital Cost

• CAPEX $20,000 to 30,000 / bbl capacity.

• 30,000 BPD plant costs $600 - 900 million.

• Only economic above 30,000 BPD capacity.

• Syntroleum claim economic at 2,500 BPD.

• Cost breakdown:

– Syngas production 55%

– FT reaction 35%

– Product upgrading 10%

• Oryx estimated cost $950 million, $28,000/bbl.

• Pearl estimated cost is $6 billion, $23,000/bbl.Slide 49© Dr. Richard J Barnes 2015

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ConsultingFeedstock

• Free of sulphur compounds

• Limited inerts (CO2, N2, etc).

• Feed gas consumption 8,000 to 10,000 SCF / bbl.

• Oxygen consumption 0.25 tonne / bbl.


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ConsultingThe Future

• 93 gasfields with reserves exceeding 5 TCF.

• Most of these are “stranded”, that is have no infrastructure.

• All GTL plants require significant investment, typically $1 billion or more.

• The economic size of plants is decreasing.

• Shell is considering building in Trinidad, Iran and Egypt.


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ConsultingCompactGTL

Slide 52

• A new concept still in development.

• Uses compact reactors to make small plants economic.

• No commercial projects.

• Suitable for ship installation.

© Dr. Richard J Barnes 2015

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ConsultingCompactGTL Pilot Plant

Slide 53

• Commercial Demonstrator Plant commissioned in Brazil in 2011.


Source: http://compactgtl.com/wp-content/themes/modular/images/petrobras.jpg

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ConsultingCompactGTL Advantages

Slide 54

• Does not require oxygen plant.

• Steam methane reformer and F-T reactor are based on plate and fin exchangers with supported catalysts.

• Reactors can be changed out on line when spent.

• No product work up as GTL product is mixed with crude oil.


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Consulting


End of Presentation


Documents

Lecture 14 LNG Alternatives R2 - Frederick Universitystaff.frederick.ac.cy/eng.ap/FALL2016/MOE506/Lecture … · · 2016-12-0505/12/2016 2 Energoil Consulting Compressed Natural