LNGLIQUEFACTION, SHIP AND REGASIFICATION

GAS MANAGEMENT PROGRAMDEPT. OF CHEMICAL ENGINEERING

UNIVERSITY OF INONESIA

What is LNG?

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Source: IELE

Typical properties of LNGLNG is simply natural gas that has been cooled to its liquid state at atmospheric pressure: - 162.2°C and 14.7 psiaLNG is transported at ambient pressures.Liquefying natural gas, which reduces the gas into a practical size for transportation and storage, reduces the volume that the gas occupies more than 600 timesLNG is considered a flammable liquidLNG vapor is colorless, odorless, and non-toxicLNG vapor typically appears as a visible white cloud, because its cold temperature condenses water vapor present in the atmosphere.The lower and upper flammability limits of methane are 5.5% and 14% by volume at a temperature of 25°C

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Natural Gas Components

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Composition Comparison

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LNG Heating ValuesLNG Heating Values depends on the content of heavy hydrocarbons (C3, C4) and varies between sourcesHeating Values requirement also varies between markets: Japan: 1,120–1,150 BTU/Cft

Europe: 990–1,070 BTU/CftUSA: 1,020-1,075 BTU/Cft

Heating Values has thus to be adjusted to each marketIt can be reduced by extraction of C3/C4 at liquefaction plant, mixed with lower BTU gas, or inject nitrogenIt can be increased by adding propane (Japan)

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LNG Heat Content (Btu/cft)

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Specific Gravity and Wobbe Index

The Specific Gravity of gas is defined as the ratio: Density of gas/Density of air.Density of air is 1.29 kg/m3, Specific Gravity of air is 1.0.The Specific Gravity of natural gas is in the range of 0.55 to 0.60.The heat efficiency of a burner is measured by the Wobbe Index of gas, defined as: Gross Calorific Value/ (Specific Gravity)1/2

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Natural Gas problem is VolumeFor the same energy content:

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LNG Plant

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Types of LNG plant

1. Land-based LNG

•LNG fuelling station (0.5-10 mmscfd, 0,004-0.08 MTPA) •Peak Shaving LNG Plant (5-20 mmscfd, 0.04 – 0.15 MTPA)•Decentralize LNG Plant (50-250 mmscfd, 0.3 – 1.7 MTPA) •Based Load LNG Plant (300-1000 mmscfd, 2 – 8 MTPA)

2. Offshore-based LNG•Floating LNG (150-300 mmscfd, 1-2 MTPA)

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Based load plant

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Peak shaving plant

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Peak shaving principle

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Satellite LNG Storage

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Decentralize LNG plant

Capacity: 130 tpd, 0.04 MTPA© PEUI -2007

LNG satellite

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LNG satellite principle

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LNG fuelling stations

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LNG trailers

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LNG tank for vehicle

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LNG tank for heavy vehicles

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Floating LNG

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Liquefaction Process

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Basic refrigeration cycles

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Natural gas/refrigerant cooling curve

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Vapor pressure vs. temperature

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Baseload liquefaction processesAir Products’ propane pre-cooled MR (PPMR) uses nitrogen,

methane, ethane, propane. Gas feed initially cooled by propane chiller to - 35°C. Liquid/vapor streams chilled further before flashedacross J-T valves to provide cooling for final gas liquefaction. Usedin 82% of baseload plants and APCI also moving into small andmedium-scale plant

Phillips’ original optimized cascade LNG process uses propane/ethylene circuits, methane flash circuit, brazed-aluminumheat exchangers and core-in-kettle exchangers

Statoil/Linde LNG Technology Alliance’s mixed-fluid cascade process uses three MR cycles to pre-cool, liquefy, sub-cool purifiedgas. Linde makes proprietary spiral wound heat exchanger(SWHE)

Shell’s dual MR process has two separate MR cooling cycles using SWHEs and process configuration similar to PPMR process. Shell also has single MR process

IFP/Axens’ Liquefin produces LNG at very high capacities and istwo-MR process for new LNG baseload projects of 6 MTPA train sizes

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Base load LNG Lisensor

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LNG Production Scheme

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Liquefaction Technologies

1. Mixed Refrigerant Process (MCR)- Refrigerant= a mix of propane, ethane, methane- Feed gas pre-cooled at -35/-60o C- Main cooling in Heat Exchanger (Spirally Wound or Plate Find)

2. Cascade Process- Cooling in three stages- Propane to -35o C- Ethylene to -105o C- Methane to -161o C- Heat Exchangers: Plate Fin

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Schematic Mix Refrigerant System

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Mixed Refrigerant Cycle Process (Liquefin)

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Mixed Refrigerant Cycle Process (APCI)

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LNG Process: Badak

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Mixed Refrigerant Cycle Process (Statoil/Linde)

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Optimized Cascade Process (Phillips)

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Expander Cycle

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LNG process selection

Source: LNG 2000 Smi Conference, England, February 2000.

1.70Double Expander Cycle

1.70Single Expander With Pre-Coolore Propane Cycle

2.00Single Expander Cycle1.05Multi Stage Mixed Refrigerant Cycle

1.15Mixed Refrigerant With Pre-Cooler Propane Cycle

1.25Single Stagemixed Refrigerant Cycle1.00Cascade Cycle

Power Consumption Relative to Cascade

CycleLiquefaction Cycle

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Main exchange line typical arrangements –Front View

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Main exchange line typical arrangements –Top View

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Plate Fin Heat Exchanger

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Australia North West Shelf Liquefaction Plant

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Badak Liquefaction Plant, Indonesia

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Liquefaction Process TrendImprovement of Cascade Process using Plate Fin ExchangersNew Technology using MCR Process by Axens/IFP, Linde (Liquefin)Use of larger Gas Turbine Use of Electrical Drivers instead of Gas TurbineIncrease of capacity for a single train, up to 8 Tons of LNG

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Small and Mid-Scale LiquefactionProcesses (1)Black & Veatch’s PRICO process uses single-MR loop/single refrigeration compression system: nitrogen, methane, ethane, propane, iso-pentane. MR compressed/partially condensed priorto entering cold box w/PFHE cores. Used for peakshaving, vehicle fuel supply, gas distribution systems: 4 to >180 MMscfd. MR system used for baseload, peakshaving. BV has 16 operating plants: 4 to 360 MMscfd and nine projects underdevelopment. Linde LE’s advanced single-flow for mid-scale 0.2-1.0-MTPA plants. Liquefaction occurs in SWHE. Basic single-flow for small<0.2 MTPA plants such as peakshaving or mini-LNG. Pre-cooling, liquefaction & sub-cooling occurs in 1 or 2 PFHE(s).Kryopak’s EXP - single-cycle turbo-expander refrigeration uses inlet process gas as refrigerant. No mixed refrigerant (MR) required. PCMR - pre-cooled MR: nitrogen, methane, ethane, butanes w/ conventional refrigeration circuit for pre-cooling. SCMR - single-cycle MR: nitrogen, methane, ethane, butanes and pentane

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Small and Mid-Scale LiquefactionProcesses (2)

Chart Energy & Chemicals provides process design thruengineering, construction, startup to meet small-plantrequirements. Designed cold boxes for Phillips Cascade Process and provides aluminum plate and core-in-kettleheat exchangers.

Mustang Engineering’s LNG Smart requires norefrigerant production. Eliminates MRs. Uses inlet gas as sole refrigerant medium. Gas enters multistage process via compression, turbo-expansion.

Hamworthy offers small-scale plant using closed nitrogenexpansion loop providing required cold duty to liquefy gas. Mini-LNG plant uses pipeline or landfill gas

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General Scheme of a SS plant (Closed-loop)

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General Scheme of a SS plant (Open-loop)

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Mixed Refrigerant Cycle Process (Black & Veatch Prico)

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Mid-Scale LNG Process

Source: Verghese© PEUI -2007

Small Scale Plants, Process, Efficiency and Capacity

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LNG process selection for small and mid scale (SMS)Criteria Expander Liquid Refrig.

Compactness

Weight

Inherent safety

Suitable for marine environment

Ease of operations

Ease of start-up

Equipment count

Availability

Cycle robustness

Efficiency

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LNG process selection for SMS

Source: LNG 2000 Smi Conference, England, February 2000

LowHighHighTotal Investment Cost

HighAverageHighChanging Gas Feed Flexibility

HighLowAverageStart-up/Shutdon Simplicity

HighLowAverageOperation Simplicity

LowAverageAverageVessel movement Sensitivity

NoYesYesRefrigerant Tank Risks

LowHighHighOverall Location Needed Area

YesYesYesUse guarantee technology

ExpanderMRCCascadeCriteria

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Mid-Range (MR) LNG(GasConsult Ltd and Energy and Power Consultant Ltd)

LNG outputs from 300,000 – 1 million tpy LNG (approximately 50-150 mmscfd feed gas).Estimated investment and production costs 30% lower than with scaled down conventional mixed refrigerant cycle process effectively matching large scale mixed refrigerant economic at a small scale.Potential application include ‘stranded’ natural gas and associated gas, upgrading existing LNG facilities and peak shaving.Refrigerant can be obtained directly from feed gas without columns or storage.Low hydrocarbon inventory enhances safety offshore and onshore.Process consists of proven equipment.Recycle type will be simple to operate with convenient turndown.Modular construction enables rapid installation in remoteenvironments or offshore applications.

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Coldbox of MRLNG

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LNG SmartTM (Mustang)

LNG SmartTM tank design © PEUI -2007

LNG SmartTM (Mustang)

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Offshore Facilities

Source: Moss MaritimeFLNG: Floating LNGFSRU: Floating Storage Regasification Unit

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LNG Shipping

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Characteristics of LNG Tanker Fleet

Two types of tanker design: Membrane design and Kväerner-Moss spherical designExisting Fleet (2004): 141 Ships; on order: 52 shipsCurrent capacity of LNG ships on order: 135,000 to 145,000 m3

Membrane ships are increasing their share: 63% of all ships on order compared to 43% in existing fleet.

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Choice of containment system

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Moss vs. Membrane ShipIllustration of Dimensions and Tonnage

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LNG Ship Maximum Capacity –Progression

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Kväerner-Moss Ship built in 1990135,000 m3 – 276 m

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Membrane ship built in 2004 (Madrid)138,000 m3 – 124 m

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Kväerner-Moss Ship Structure

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Membrane Ship Structure

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Structure of Membrane hull

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LNG tankers

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LNG tankers

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LNG Tanker Fleet (2004)

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Comparative Characteristics of LNG Tank Systems

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LNG Receiving Terminal

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LNG Receiving Terminal Facilities

Jetty for berth and unloadingMonitoring dolphins, manifold unloading arms, security systems

Storage tanksDesign: single, double or full containment, or membrane

Regasifying facility: vaporizersConnection to pipeline system

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LNG Receiving Terminal

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LNG Marine Terminal Scheme

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Cold Utilization (1)

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TG CompressorGasTurbine

TG CompressorGasTurbine

LNG Vaporizer

SolutionHeater

Seawater

Solution Pumps

Tanque Solución

LNGGAS

Air Filter & Chiller Seawater

12 ºC

2 ºC

2 ºC

12 ºCAir Inlet 17 ºC

Air Inlet 17 ºC

Air

7 ºC

Air

7 ºC

Air Filter & Chiller

By-pass

Solution Tank

Cold Utilization (2)

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VaporizersOpen Rack Vaporisers (ORV) are common worldwide and use

seawater to heat and vaporise the LNG in an open, falling film type arrangement. In general, for using ORVs the preferred seawater temperature is always above 8 °C. The seawater is chlorinated to protect the surface of the tube panel against bio-fouling and to prevent marine growth inside the piping.

Submerged Combustion Vaporisers (SCV) use send-out gas as fuel for the combustion that provides vaporising heat. The SCV vaporizes LNG contained inside stainless steel tubes in a submerged water bath with a combustion burner. In the baseloadterminal SCV, the fuel gas is burned in a large single burner rather than multiple smaller burners because it is more economical and it achieves low NOx and CO levels. The hot flue gases are spargedinto a bath of water where the LNG vaporization coils are located.

Due to the high cost of the seawater system ORV installations tend to have a higher installed capital cost while the SCV installations have a higher operating cost because of the fuel charge.

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VaporizersShell and Tube Vaporizers (STV): The STV and Intermediate Fluid STV

type are generally smaller in size and cost competitive compared to an ORV or SCV system. Heat is usually supplied to the LNG vaporizer by a closed circuit with a suitable heat transfer medium. They are mainly used when a suitable heat source is available. Design of these types of vaporizer systems requires a stable LNG flow at design and turndown conditions with provisions to prevent the potential for freeze-up within the vaporizer. The design of Double Tube Bundle STV incorporates both a lower and an upperset of tube bundles, and uses an intermediate heat transfer fluid (e.g. propane, isobutane, freon, ammonia) between the LNG (upper tubes) and the seawater or glycol water (lower tubes) inside a single shell. A small shell and tube superheater is required to heat the vapor to 5 °C.

Combined Heat and Power unit with Submerged Combustion Vaporize(CHP-SCV): In order to decrease the gas auto-consumption of SCVs, as well as to increase the efficiency and economics of the entire regasification process, the receiving terminal can be modified to use a cogeneration concept that offers energy saving and environmental advantages. This has been implemented at the Zeebrugge LNG Terminal Cogeneration Project. The heart of the CHP facility is a gas turbine type LM6000 that generates 40 MW of electrical power. The hot exhaust gases from the turbine pass through a heat recovery tower and transfer their heat to raise the temperature of a closed hot water circuit. This hot water will then be circulated and injected in the water bath of the vaporizers and transfer its heat to regasify the LNG. © PEUI -2007

ORV

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Open rack type

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SCR

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Shell and Tube Vaporiser

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Loading arms

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LNG Storage Facility

Several components, that:- allow unloading ships without delay- provide storage for compensating delay in ships arrival- provide storage for facing seasonal variations- provide strategic storage, if possible

Current storage capacities:- Japan Sodegaura: 2,700,000 m3 including strategic storage- Korea Incheon: 2,200,000 m3 including seasonal demand- France Fos: 150,000 m3 including including size of ships 70,000 m3

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Above ground-LNG Storage

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In Ground, UndergroundLNG storage

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LNG Tank Containment

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LNG Tank Containment

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LNG Storage Tank Schematic

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LNG Storage Tank140,000 m3 double containment

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LNG Receiving Terminal

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Offshore LNG Terminals

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FSRU Gravity Based Structure

Source: Brian Raine, LNG Journal

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LNG Safety

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