Computational Fluid Dynamics Simulations of accidental releases from LNG bunkering operations Background Sulphur emission regulations implemented by the International Maritime Organisation

Computational Fluid Dynamics Simulations of accidental releases from LNG bunkering operations
Background
Sulphur emission regulations implemented by the International Maritime Organisation (IMO) listed in the International Convention for the Prevention of Pollution from Ships (MARPOL) Annex VI Regulation 14 have led to a drive from marine transport companies towards alternative fuels. ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “ISBN” : “9789211129229”, “abstract” : “The Review of Maritime Transport is a recurrent publication prepared by the UNCTAD secretariat since 1968 with the aim of fostering the transparency of maritime markets and analysing relevant developments. Any factual or editorial corrections that may prove necessary, based on comments made by Governments, will be re ected in a corrigendum to be issued subsequently.”, “author” : { “dropping-particle” : “”, “family” : “UNCTAD”, “given” : “”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issued” : { “date-parts” : “2017” }, “number-of-pages” : “130”, “title” : “UNCTAD Review of Maritime Transport 2017”, “type” : “book” }, “uris” : “http://www.mendeley.com/documents/?uuid=68470c33-b5de-4d4b-80df-cecbbd93e8d8” } , “mendeley” : { “formattedCitation” : “(UNCTAD, 2017)”, “plainTextFormattedCitation” : “(UNCTAD, 2017)”, “previouslyFormattedCitation” : “(UNCTAD, 2017)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(UNCTAD, 2017). Liquefied natural gas (LNG) is seen as a very viable alternative to the heavy fuel oils (HFOs) currently in use as its combustion releases no Sulphur emissions ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Herdzik”, “given” : “Jerzy”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Journal of KONES Powertrain and Transport”, “id” : “ITEM-1”, “issue” : “2”, “issued” : { “date-parts” : “2011” }, “page” : “3-10”, “title” : “LNG AS A MARINE FUEL u2013 POSSIBILITIES AND PROBLEMS”, “type” : “article-journal”, “volume” : “18” }, “uris” : “http://www.mendeley.com/documents/?uuid=d75ba5a6-8d22-4b11-a2a8-1d186207edc6” } , “mendeley” : { “formattedCitation” : “(Herdzik, 2011)”, “plainTextFormattedCitation” : “(Herdzik, 2011)”, “previouslyFormattedCitation” : “(Herdzik, 2011)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Herdzik, 2011). Ships are refuelled with LNG at bunkering stations in ports via ship-to-ship, truck-to-ship or terminal-to-ship techniques. Leaks may occur during bunkering due to equipment faults or human error. Due to the high methane content of LNG, a leak will result in a dispersion that could pose a significant safety risk.

Purpose, Significance and Novelty
The purpose of the research is to model the extent to which LNG disperses as the result of an accidental release during a bunkering operation. Results gained from the models can be used to further understand and implement recommendations for the size of the safety and monitoring and security areas during bunkering operations. Simulations will be performed using the Flame Acceleration Simulator (FLACS) to investigate the way that the dispersion interacts with a fully representative geometry in scenarios that represent different environments, positions and LNG flow rates. The application of FLACS to the scenarios investigated in this project is a novel use of the software.

Objectives
The objectives of the proposed research using the FLACS Computational Fluid Dynamics software will be:
To simulate LNG dispersion scenarios over flat ground with no obstacles.

Compare results from FLACS software against results collected from simple modelling techniques
To simulate LNG dispersion scenarios with geometry that is fully representative of the bunkering operation.

To provide recommendations on the size of the safety and monitoring and security areas during bunkering operations in different conditions.

Methodology and Work Plan
Phase 1 – FLACS orientation:
Familiarisation with the FLACS software by completing training materials and examples. Ensure particular attention is paid to jet pool simulations. Practice setting up and running individual leak and dispersion models
Phase 2 – Selection of scenarios:
Define realistic scenarios based on industry data for variables such as wind speed, atmospheric stability (Pasquill class), leak position, leak diameter and flow rate.

Phase 3 – Collation of data from simple modelling techniques:
Collect data on LNG dispersions for scenarios defined in Phase 2 using simple modelling techniques to use as a reference for FLACS simulations.

Phase 4 – Simulation of flat ground scenarios using FLACS.

Build geometry and simulate LNG dispersion over flat ground with no obstacles for the scenarios defined in Phase 2.

Phase 5 – Validation of FLACS software against simple modelling techniques
Compare data collected from flat ground simulations to data collected from simple modelling techniques in order to confirm the validity of the FLACS software.

Phase 6 – Simulation of full geometry scenario using FLACS.

Build geometry that is fully representative of various bunkering operations at ports (truck-to-ship, ship-to-ship, terminal-to-ship). Simulate LNG dispersion in this geometry for the scenarios defined in Phase 2.

Impact and Beneficiaries
If successful, this research will confirm the applicability of FLACS to LNG dispersion scenarios during bunkering operations at ports. The applicability will depend on the accuracy and speed of delivery of results from the software compared to simple modelling techniques. The main beneficiary will be DNV GL through an improved portfolio of knowledge on the topic and the confirmation of the applicability of FLACS as a tool to better understand the interaction of LNG dispersions with complex geometries.

Task WEEK COMMENCING
5th Feb 12th Feb 19th Feb 26th Feb 5th March 12th March 19th March 26th March 2nd April 9th April 16th April 23rd April 30th April 7th May 14th May 21st May 28th May 4th June 11th June 18th June
Project plan submission -62865-127000 Interim report submission -65405-1270000 PDP report submission 64135-381000
Statement of professional development 64135127000
FLACS training material and examples   Background reading on topic     Type up Project Plan   Selection of dispersion scenarios   Collation of data from simple modelling techniques       Develop scenario and geometry for simulation over flat ground   Simulation of dispersion scenarios over flat ground     Validation of FLACS against simple modelling techniques     Develop scenario and geometry for simulation with fully representative geometry       Interim report type up     Simulation of dispersion scenarios with fully representative geometry       Collate and analyse results     PDP report type up        
Statement of professional development type up    
N.B – Predicted timescales prior to 16th March are stretched to represent time spent on literature review
References:
ADDIN Mendeley Bibliography CSL_BIBLIOGRAPHY Herdzik, J. (2011) ‘LNG AS A MARINE FUEL – POSSIBILITIES AND PROBLEMS’, Journal of KONES Powertrain and Transport, 18(2), pp. 3–10.

UNCTAD (2017) UNCTAD Review of Maritime Transport 2017. Available at: http://unctad.org/en/PublicationsLibrary/rmt2017_en.pdf.