FLACS-Risk v1.1 (r1-3) · Follows basic Norsok Z-013 methodology. FLACS User Group Meeting 28 –29 Nov 2017, London, UK Explosions (Real dispersion cloud explosions)

FLACS User Group Meeting 28 – 29 Nov 2017, London, UK

FLACS-Risk v1.1 (r1-3)

Djurre Siccama, Gexcon Software


Outline

►What is FLACS-Risk?

►Brief overview of existing functionality(Basic workflow, Dispersion, Fire etc.)

►Overview of new functionality in FLACS-Risk v1.1 (r1-r3)

►A few case studies

►Q&A


What is FLACS-Risk?

► Add-on module for regular FLACS software► Efficient framework for setting-up simulations for:

▪ Non-risk based parametric studies▪ Risk based studies

► Tool that calculates both consequences and event frequencies► Allows visualisation of risk in 1D, 2D and 3D► Focussed on input to design (e.g. DiAL and DeAL)► Utilised the FLACS CFD Solver

► Versions:▪ 1.0 (Ventilation, Dispersion, Fires) (Released 13th March 2017)▪ 1.1 adds explosions and other improvements (Released 1st September 2017)▪ 1.1r2 Cloud file support for explosions (Released 24th September 2017)▪ 1.1r3 Performance improvement & FLACS-Cloud (Release planned December 2017)


Key benefits of FLACS-Risk

►Reduce lead time for running either

▪ Non-risk based parametric studies

▪ Risk based studies

►Novel 3D Risk visualisation technique (allows visualising special distribution)

►Uses validated FLACS CFD Solver

►Project based vs individual scenario file based


Brief overview of existing functionality v1.05

(Released 31st March 2017)

► Project based (vs individual scenarios in regular FLACS)► UX focussed GUI► Gas and liquid dispersion► Gas phase jet fires and liquid pool fires► Release modelling

▪ Steady state (either indefinite or time limited)▪ Transient releases for gas phase

► Automatic grid refinement► Can stop dispersion simulations when steady state has been reached► Aimed at input to design (e.g. DiAL and DeAL)► Calculate lethality for toxic and fire exposure (based on probit function)► 1D, 2D and 3D risk visualisation► Boxplots to compare results when doing parametric studies


Main interface (1)


Main interface (2)


Overview: Running simulations


New key concepts in FLACS-Risk: Metadata instead of jobnumber logic

x1xxxxx is Natural gasx2xxxxx is Propane

xxxxxx0 is leak in +Xxxxxxx1 is leak in -X

Conventional FLACS method (using jobnumber logic)

Composition: MethaneComposition: Propane

Leak Direction: +XLeak Direction: -X

Geometry: Base_GeometryGeometry: Geo_Larger_Vents

FLACS-Risk (using metadata)

X X

Etc.


New key concepts in FLACS-Risk: Metadata instead of jobnumber logic

In scenarios file:%!TAGS="Geometry%3Dco010100.dat3%2CIgnition%3DAlways ignite%2CIso section and leak rate%3D1G %2F 96 kg%2…….%!FREQUENCY=0.025

In scenarios file:%!TAGS=“ Geometry=co010100.dat3,

Ignition=Always ignite,Iso section and leak rate=1G / 96 kg/s,Leak=Leak Leak 1,Leak direction=Dir +Z,Refine=Refine grid,Root=Project,Scenario=scenario 0,Wind=Wind 45/2FPSO Flare rerun (far field),Risk"

%!FREQUENCY=0.025

URL decoder to convert special characters(e.g. https://www.urldecoder.org/ )

https://www.urldecoder.org/


Updating existing python scripts to benefit from metadata in post processing


Example Reporting: Box plots for parametric studies


Example Reporting: Box plots for parametric studies(with scenario details for outliers)


Example Reporting: Risk Contours

1D

2D

3D

▪ 1D “exceedance curves” for specified targets (e.g. fire walls, equipment etc)

▪ 2D and 3D risk visualisation (showing spacialdistribution of risk based loads)

▪ Show contributions from different events and/or scenario properties (e.g. gas type, release rate etc.)

Freq

uen

cy[1

/yr]

Overpressure [barg]


New functionality in FLACS-Risk v1.1(Released 1st September 2017)

► Coupled project (ventilation + dispersion)► Explosions

• Equivalent stoichiometric cloud• Real dispersion cloud explosions• OLF ignition model• Semi-automated gridding for explosions• Pressure relief panels

► Project version control by snapshots.► Additional presentation templates

► What’s included?▪ FLACS-Risk Installation files (same package as FLACS v10.6r2)▪ Example risk projects▪ FLACS-Risk user manual


New functionality in FLACS-Risk v1.1r3(Release planned December 2017)

►Performance improvements

▪ FLACS-Risk Stress testing:

• 13000 FLACS scenarios

• 200mb geometry

• 7000 monitor points

• 7000 panels

• 100 monitor regions

►FLACS-CLOUD support


Coupled project (ventilation + dispersion)


Explosions (Equivalent Stoichiometric clouds)

►Follows basic Norsok Z-013 methodology


Explosions (Real dispersion cloud explosions)

►Goal: Streamline exploding of real dispersion clouds and allow use in risk studies

►Steps:

▪ Automatically import and resample dispersion cloud

▪ User select dispersion cloud time for ignition

▪ Automatically finds ignition points at boundary of real cloud (where ER = 0.75-1.25)

▪ Generate explosion scenarios

▪ Run simulation



►1. Run Dispersion cases



►2. Evaluate results



►3. Setup explosion simulations and link dispersion cloud. FLACS-Risk will automatically find 6 ignition points at boundary of cloud where ER= 0.75 – 1.25



►3. Run simulations



►4. Evaluate explosion results


Explosions (OLF ignition probility model)

►Basic OLF ignition probability model implementation

►Steps in FLACS-Risk:▪ Run dispersion simulations▪ Set OLF parameters and export ignition probabilities outputs= >• Combined intermediate file with ignited cloud frequencies• Intermediate file (for each scenario) ignition summary (for QA purposes)

▪ Setup explosion simulations (including desired cloud size categories)▪ Import ignited cloud frequency file• Frequencies are automatically set for each cloud size category

𝑃𝑖𝑔𝑛𝑑𝑖𝑠𝑐𝑟𝑒𝑡𝑒(𝑡) = 𝑃𝑖𝑓−𝑑𝑖𝑠𝑐 ∙ 𝑉𝑛𝑒𝑤(𝑡) ∙ 𝐹𝑑(𝑡)

𝑃𝑖𝑔𝑛𝑐𝑜𝑛𝑡 𝑡 = 𝑃𝑖𝑓−𝑐𝑜𝑛𝑡 ∙ 𝑉𝐿𝐹𝐿:𝑈𝐹𝐿(𝑡) ∙ 𝐹𝑐(𝑡)


Explosions (OLF ignition probility model)


Explosions (OLF ignition model)(verification using example from MISOF report)

0.00E+00

2.00E-04

4.00E-04

6.00E-04

8.00E-04

1.00E-03

1.20E-03

1.40E-03

0 50 100 150 200

Ignition probability model verification (Continuous ignition)

Pc (data from MISOF report) Pc (from FLACS-Risk)

0.00E+00

2.00E-05

4.00E-05

6.00E-05

8.00E-05

1.00E-04

1.20E-04

1.40E-04

1.60E-04

1.80E-04

2.00E-04

0 50 100 150 200 250 300

Ignition probability model verification (Discrete ignition)

Pd (data from MISOF report) Pd (from FLACS-Risk [5s step])


Explosions (Semi-automated gridding for explosions)

► Automatic steps in FLACS-Risk

1. Find grid sizes compatible with module dimensions and cubical (within +-10%)

2. Identify largest grid size from list above that satisfies (conservative) grid requirements for gas cloud

▪ At least 13 cells horizontally (valid for any type of confinement)

▪ At least 10 cell vertically (valid for at least confinement on one side)

3. Apply homogenous cubical grid size to module area and 5 cells outside

4. Stretch domain beyond cubical area



Module28m x 12m x 8 m

Gas cloud15m x 10m x 7.5m

In this caseFLACS-Risk suggested grid: 0.757m x 0.750m x 0.750mGives respectively 20, 13 and 10 cells across cloud

Cubical core gridStretched grid



►LIMITATIONS:►Automatic gridding will not work in the following

situations!(But grid can be modified manually within FLACS-Risk)▪ Multiple decks or walls that need to be aligned to the grid▪ If the walls that need to be aligned do not match defined

module boundary.▪ If the cloud is not bounded in vertical direction on any side

(this is very unusual, as in most cases a cloud will be modelled either on the ground or deck or underneath a roof.

▪ Equally spaced repeated objects▪ Hydrogen specific grids (due to the high reactivity of hydrogen

a finer grid is required)


Explosions Pressure relief panels (1)


Explosions Pressure relief panels (2)


Project version control by snapshots.


Additional presentation templates


Future developments►Incorporating more methodology to

reduce number of required FLACS simulations => NORSOK etc.

►Analytical FLACS pseudo solver => visualisation in Flowvis/Risk?▪ TNO ME▪ Disperison▪ Fire


Selected Case studies

►FPSO

▪ Flare parametric study

▪ FPSO ERA

►LNG Pool dispersion risk study

►Toxic dispersion risk study


Case studies: FPSO Explosion risk study (screening)

► Generic FPSO

► 1. FPSO Flare parametric study▪ Wind conditions: 8

▪ Flare vent rates: 4 • 96 kg/s (=346 metric tons / hour)

• 192 kg/s

• 384 kg/s

• 768 kg/s

▪ 32 Scenarios

▪ Calculation time (approx. 4 hours)

► 2. Explosion risk study (quick screening)▪ Single module

▪ Propane

▪ 3 Cloud sizes 500 m3, 1000 m3 and 2700 m3

▪ 25 scenarios

▪ Calculation time (approx. 3-5 hours)


Case studies: FPSO Flare parametric study


Case studies: FPSO Explosion risk study






Case studies: LNG Pool dispersion risk study


Case studies: Toxic dispersion risk study

► Onshore facility► Different releases 7.5barg pressure, propane (two

different isolatable sections, one with 5% H2S and one with 3% H2S)

► 16 Wind condition combinations modelled► 7 Leak locations / 15 Leak hole size/location combinations

modelled (22mm, 70mm and 150mm) – steady state releases

► Assumed steady state release and simulation time 100s► Lethality calculated using one of the default TNO Probit

function in FLACS-Risk► Total combinations 1,440 (e.g. FLACS simulations)► Calculation time: approx. 2 days on a small cluster (200

cpu’s)


Case studies: Toxic dispersion risk study


How to get FLACS-Risk

►Until 31st December 2017 we offer:

▪ Special introductory price for the FLACS-Risk add-on

▪ Free 1-month trial of FLACS-Risk add-on for existing FLACS users*

* With a valid FLACS license

►For any questions related to FLACS-Risk (including pricing) contact us at [email protected]

mailto:[email protected]


Summary

This presented covered:

► What is FLACS-Risk► Key benefits of FLACS-Risk► Existing and new features in

FLACS-Risk v1.1► Selected case studies► How to get FLACS-Risk

► For any questions related to FLACS-Risk contact us at [email protected]

mailto:[email protected]


Questions?

FLACS-Risk v1.1 (r1-3) · Follows basic Norsok Z-013 methodology. FLACS User Group Meeting 28 –29 Nov 2017, London, UK Explosions (Real dispersion cloud explosions)

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