2009 fpso research forum dsme

8/13/2019 2009 FPSO Research Forum DSME

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Safety Concept of DSME LNG FPSO:A shipbuilders perspective

Sung Hoon Sean Kim, Ph. D.

Daewoo Shipbuilding & Marine Engineering

April 12009

2009. 4.12Future Products & Business Development Institute


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Recent/On-going projects


TOC

DSME HSE Engineering

Risk on Offshore LNG Plants

Comparison with those on Oil FPSOs

DSME LNG FPSO Features

Layout

Process

Safety Devices


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HSE Engineering in DSME

Drilling rig & drillships FPSOs

FSRU & LNG RV

Cruiseship

Reliability


LNG RV

Reviewed by LRNA & ABS

FERA

Regas facilities besidestrunk deck of No. 1 tank

Jet fire

Fire rated walls toprotect tanks

SUS Plating & Deluge atthe pump bottom

CFD Explosion analysis

Leak in the STL

Effect of Relief panel

Ventilation condition

FRA, reproduced byDSME using Neptune


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LNG FSRU

A research project FRA using Neptune Emergency relief design

Vent Flare

Toxic gas dispersion Collision Risk Assessment


Risk on Offshore LNG Plant, Myths & Facts

Myth

Explosion comparable tohydrogen bomb

Collision or vulnerability toterrorist attack?

Spill on water

Rapid phase transition (RPT)blast?

Vapor cloud traveling towarda center of population?

Total collapse of containmenttank?

A pool fire within the full tankimpounding area?

Tank top fire?

Fact

Embrittlement of steelstructure exposed to cryogenicspill

Dangerous process

High pressure, flammable

and/or cryogenic fluid Flammable refrigerant maybe

Safety by distance shall be

compromised


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Inherent Safety LR Guidance

Adequate separation / segregation of hydrocarbon inventories

Reducing the level of confinement in a hazardous area

Minimising the size of hydrocarbon inventories available for escalation

Suitable location or protection of essential systems and equipment

Use of passive systems, i.e. fire and/or blast walls and PFP, includingprotection against spills

Use of active protection systems, i.e. fire fighting, ESD, PSD.


Approach to Assess the Risk

Independent studies

Leak frequency

Dispersion

Flammable gas evaporated from LNG release Offsite hazard impact irrelevant on an offshore plant

LQ impairment due to exhaust or flammable gas, smoke, etc

Fire

Jet/Pool fire & the frequency of escalation

Passive fire specification

CFD Explosion

Congested semi-closed modules

Ductility level blast specification

Drop object

Collision

Side-by-side offloading and/or tandem offloading

QRA

Not only related with the process failure but with non-hydrocarbonaccidents


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Oil FPSOs by DSME

Pazflor

AGBAMI


Comparison of Risks on Oil FPSO & FLNG(1/2)

- Liquid inventory rather limited

- Liquid spill to be driven overboard- To be evaporated with energy fromambient air

- Large liquid inventory along the

process- Spill containment over the deck

-Heavy hydrocarbons with smoke

- Little evaporation when released

Pool fire

-Dense vapor just release from LNGprocess would slump over the deck

- Less confined and congested topsideto have better ventilation

- Little smoke

- Process gas heavier than air

- Smoke from the pool fire shall be

considered

Dispersion

- Readily dispersed and having lessreactivity

- Large explosion reactivityVCE

- High pressure gas inventory wouldhave more risk of jet fire

- Larger heat radiation

- High pressure gas at compressormodule

Jet fire

- Mainly C1- Hydrocarbons mainly heavier thanC3, C8, C10 and a little C1

Composition

FLNGOil FPSO


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Comparison of Risks on Oil FPSO & FLNG(2/2)

-Mainly risers through internal turretcontaining mainly gas

- Enclosed space to be mechanicallyventilated

- Two phase feed liquid

- Mainly exposed riser inlets at one

side of the vessel containing mainlyliquid

Well fluidreception

- Hot wet flaring

- Cold dry flaring

- Cold vent

- Hot wet flaring

- Cold dry flaring

- Cold vent

Flare & vent

Side-by-side & tandem offloadingTandem offloadingOffloading

- Welded stainless piping & equipmentwith the minimum number of flangeconnections

- Deluge to prevent brittle fracture

- Vapor cloud control

Cryogenichazard

Ex. 1, Large scale FLNG, 460x75 lifting50,000 ton topside ~ 1.45 ton/m2

Ex. 2, DSME LNG FPSO(Mid size),330x65 lifting 20,000 ~ 0.93 ton/m2

Ex. Agbami, 320x59 lifting 35,000ton topside ~ 1.85 ton/m2

Plantcongestion


DSME LNG FPSO

330m x 65m, topside weight about 20,000 tonProduction 2 MTA through 2 trainsProcess deck 6m above the hull deck

Living Quarter located upwindFlare tower slantedGas turbines located above the process deckExtended anchoring platform


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DSME LNG FPSO

Barge type hull Two rows of storage tanks

-Little risk from sloshing-Strong support for topside structures

Storage of 200K LNG/20K LPG Condensate to be consumed as fuel Internal turret system with weathervaning capability 2x5MW Azimuth thrusters


DSMEs Two-Row Tank/Design Evolution

Low sloshing load Small tank width leads to less internal flow

Avoid resonance with ship motion

No concerns on CCS against sloshing load

Strong support for offshore topside module Strong longi. bulkhead supports heavy

topside

Free from additional support for topside

Small deck deflection

Economical solution Cost-effective and optimum solution

comparing other Independent CCS

Centerline bhd. for

2-Row arrangement

138K LNGC 2-row FLNG

1080 1082 1084 1086 1088 1090 1092 1094 1096 1098 1100

Time [sec]

P

ressure

ImpactPressure TimeHistory

1RowTank

2RowTank

1-row

2-row

Experimental setup Model test

Pressure


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DSME LNG FPSO

Conceptual development A competitive medium-scale model for offshore non-associated gas

well (less acid & lean) Liquefaction process

SMR technology of B&V, a renowned liquefaction technology

Client-preferring technology applicable

Gas turbine driven compressors to require smaller electric load

DSME design to Float, Storage, & Offloading A barge with internal turret system and facilities for side-by-side offloading

Gas treatment & utility modules design

Cargo handling system

Two-row arrangement of GTT NO. 96 CCS

Safety consideration Conceptual layout review in the current stage

Major FLNG safety issues being considered

Detailed safety study planned


Layout Living quarter

Separated from the process area

Protected by the Fire/Blast wall No jet fire grade

Ductility level blast design

To protect the lifeboat station

STL Compartment to be separated fromthe LQ via the lay-down area Blast attenuation

Safety against the jet fire & dispersion

Grated process deck to be extended tothe LQ for easy material handling &working path


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Layout Internal turret

Harsh sea condition to prefer the internalturret system HP feed gas to be contained only within

the turret

Location To be located as close to the bow

For good weathervaning capability

Not to be close to LQ Blast relief Flammable gas Machinery space in the hull to separate

Structural integrity

Longitudinal deformation Swivel movement Blast loading

Mechanical ventilation No passive fire fighting on equipment &

structure inside the structure


Layout Gap for enhanced ventilation

Process deck Plated within process modules

To prevent the release from the topside to slump down to the hull deck

6m above the hull deck

Grated between modules to release flammable gas and explosion

Small safety gaps between modules to enhance ventilation Effect be analysed through CFD analysis


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Fire risk

Jet fire Safety gap to prevent an escalation

from the jet fire

7 or 10 minutes of direct exposure

Dimensioning jet fire shall beidentified of the frequency of 1.0E-4/yr.

Deluge, ineffective to mitigate thejet fire

Heat up analysis

Pool fire For in-site layout, BS EN 1473

15 kW/m2 on the unprotectedmetal outer surface of anadjacent LNG tank

Design spill

For an FLNG,

Cargo tank protected within the

hull

Design spill from equipmentwould be limited

0.0950.0950.0950.08hc

0.70.550.40.25f

350300250180Totalheat flux

6540155Length

>30101.00.1

Lowesmith (2007) Gas jet fire


Layout Escape route

The primary on the hull deck

An alternative & material handling way on the process deck

The secondary crossway between modules

Full redundancy allowing impairment of one route

Port & Starboard

The secondary muster area (SMA) aft

Protection of SMA against fire, explosion and heat from the flare


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Layout Clearance btn the hull & the process decks

Spaces for CCS maintenance Maintenance through liquid & gas dome

Retractable main cargo pumps

Favorable ventilation condition on the hull deck

Release at the hull deck

Hull deck piping of an LNG FPSO will be coarser than that of an OilFPSO.

Welded & insulated piping design of an LNG FPSO will be lesssusceptible to leakage.


Layout Topside Pipe Rack

Running above the main material handling way

Safe from material handling over the process deck

The material handling way as a ventilation alley & an alternativeescape route

Ladders between longitudinal modules


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Explosion Risk

Release Dispersion Ignition Explosion Release frequency & inventory to depend on detail design

Dispersion depend on Ventilation condition : Layout, confinement, congestion, buoyancy,

Ignition source shall be rated

Explosion strength

Light hydrocarbon would have small explosion efficiency

Controlled by layout

Design Overpressure once in 10,000 years

Materials NG

Cold natural gas

Propane

Refrigerant


Layout Mixed Refrigerant & Storage

Mixed refrigerant Another source of flammable gas leak

C1, C2, C3, C5 & N2 Separate storage for C2, C3, & C5

Normally No Flow from the refrigerant storage to suction drum

Located at a well ventilated area

Away from LQ & SMA

Considering re-arrange vessels longitudinally

Hazard to be considered

Heat from the flare

Drop accident from crane

operation


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Layout Offloading platform

Side-by-side offloading ofLNG only!

Protection

SUS plated under the gratedmanifold deck

Water deluges

QCDC & ESD

Consequence of release

RPT on contact with the waterwithin the gap would exert norisk

Explosion on the FLNG with littleimpact on the LNGC


Layout Flare tower

Tower slanted aft

With no condensate to be offloaded, no riskon tandem-offloading vessels

Flaring scenario (draft) No flaring in normal condition

Normal BOG will be consumed as fuel for G/T

Operation/Emergency flaring

Start-up Process shutdown

Separate vents for topside & cargo

Topside equipment maintenance

Tank purging

Tank pressure relief

Tip design & tower height will be determined

Heat shield on SMA

Heat on the MR storage tank


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Typical Liquefaction Process

Liquefaction

CryogenicRefrigeration

System

Fractionation

Produced

WaterTreatment

LNG Product

Refrigerant

DehydrationAcid Gas

RemovalEnd Flash

BOG/FG

Compression

LNGStorage Tank

Flash Gas

BOG

CO2, Sulfur

H20

H20Condensate

Storage Tank

LPGStorage Tank

InletSeparation

C5+

C5+C3+C4

C1+C2

Fuel

FeedStock


SMR Black &Veatch, PRICO

Benefits of SMR Competitive efficiency Small equipment count Compact heat exchanger adopting

aluminum plate fin

A small number of drivers Limited inventory of refrigerant Simple operation

FLNG, August, 2007


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Gas Treatment

AGRU

Little CO2 content in the feed gas from non-associated gas well

Dehydrator

2x100% Fractionation

Adjust LNG HHV & Stabilize condensate

Located around the midship to minimize the motion


Utility Gas Turbine

Gas turbine For MR compressor

Located at the upper deck above theMR process

Two trains configuration

Well separated from LQ

For electric power generation

Right behind of the LQ at the portside

Safe equipment requiring no hazardarea classification

Turbine blade rotor failure as apotential risk

Rather a common practice onoffshore plant


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Safety Device Cryogenic spill

Piping of cryogenic flow over thedeck minimized

Around the cold box and the shortdirect run-down LNG piping to cargotank

Protection Shield for HP flanges

Drip trays for LP flanges

Local SUS plating may beconsidered

Management

Deluge under the offloading station Spill overboard

Evaporation by natural ventilation

Closed drain system to return largespill

Air blower away from the vessel


Safety Device Fire fighting

Passive fire protection - Fire rating

Design fire scenario

Jet fire rating

Large inventory hydrocarbon vessels including MR storage

Primary structure such as module stools, columns, base of the flare tower

SMA aft

Hydrocarbon fire rating

Fire wall behind the LQ

Active Fire Fighting

Water deluge on area & equipment

Dry powder system

Foam monitor

Details to be considered after FERA


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Conclusion

DSME, prepared for HSE issues on an LNG FPSO!

DSME LNG FPSO Optimum design & layout will be developed to obtain

inherent safety

Process risk as well those from SMR will be controlled A compact process technology would enable a safer design

FERA will be used to manage the process risk!

Non-process risk will be controlled

HSE will be an independent discipline during wholeprocess of development

Systematic risk assessment

Structural design to withstand design accidental loads


DSMEFuture Products & Business Research Institute

Sung Hoon Sean KimT. +82-2-2129-0864

E. [email protected]

Thank you!

2009 fpso research forum dsme

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