User:Milton Beychok/Sandbox: Difference between revisions

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In its liquid state, LNG is neither flammable or explosive.<ref name=CalifEnergyCommission/><ref>[http://www.ferc.gov/o12faqpro/default.asp?Action=Cat&ID=26 Frequently Asked Questions:  LNG]] From the website of the [[Federal Energy Regulatory Commission]]</ref> For LNG to burn, it must first vaporize, then mix with air in the proper proportions (the [[Flammability limit|flammable range]] is 5 to 15 volume percent<ref>'''Note:''' If there is less than 5 volume % or more than 15 volume % of natural gas vapor  in the air, the gas will not burn.</ref>), and then be ignited. The natural gas vapor cloud formed from by an LNG leak, spill or other release is not explosive unless the vapor is confined, either partially or fully.  In the case of a leak, LNG vaporizes rapidly, turning into almost pure gaseous methane, and mixes with air.  If the mixture is within the flammable range, there is a risk of ignition which would create [[fire]] and [[thermal radiation]] hazards.
In its liquid state, LNG is neither flammable or explosive.<ref name=CalifEnergyCommission/><ref>[http://www.ferc.gov/o12faqpro/default.asp?Action=Cat&ID=26 Frequently Asked Questions:  LNG]] From the website of the [[Federal Energy Regulatory Commission]]</ref> For LNG to burn, it must first vaporize, then mix with air in the proper proportions (the [[Flammability limit|flammable range]] is 5 to 15 volume percent<ref>'''Note:''' If there is less than 5 volume % or more than 15 volume % of natural gas vapor  in the air, the gas will not burn.</ref>), and then be ignited.  


When an LNG is released into the atmosphere because of a leak, spill or any other cause (on land or at sea), it immediately begins to vaporize by absorbing heat from the ground  or the sea water. At the usual ambient  air temperature of about 15 to 40 °C, natural gas is much lighter than air. However, the natural gas vapor formed when LNG vaporizes is very cold  (i.e., −160 °C) and therefore much denser than the ambient air. The vapor begins mixing with air and water moisture in the air is condensed to form a visible vapor cloud. . As the cloud is initially formed, it contains too much natural gas to be flammable. The cloud will linger near ground level until further heat is absorbed and the natural gas rises and mixes with more air. As that occurs, the concentration of natural gas within the cloud begins to decrease.. At some point, the natural gas concentration in the cloud will decrease to the point where the gas is in the flammable range and becomes ignitable. If an ignition sources is present at that point, only the part of the cloud which is within the flammable range  will burn. The vapor cloud will not explode unless it is confined. Any part of the cloud that enters a building or becomes confined in a congested area will become explosive if encounters an ignition source.<ref name=Pitblado>{{cite book|author=John M. Woodward and Robin Pitblado|title=LNG Risk Based Safety: Modeling and Consequence Analysis|publisher=John Wiley and [[American Institute of Chemical Engineers]]|date=2010|id=ISBN 0-470-31764-7}}</ref><ref>[http://www.nyserda.org/Energy_Information/lngstudy.pdf Report On Issues Regarding The Existing New York Liquefied Natural Gas Moratorium] 1998, from the website of the New York State Energy and Research Development Authority (NYSERDA). The report concluded that safety concerns associated with LNG terminal facilities were adequately addressed by existing Federal, State and local statutes and regulations. For those reasons, the study recommended: that the New York State Legislature discontinue the existing moratorium.</ref>




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*{{cite book|author=John M. Woodward and Robin Pitblado|title=LNG Risk Based Safety: Modeling and Consequence Analysis|publisher=John Wiley and [[American Institute of Chemical Engineers]]|date=2010|id=ISBN 0-470-31764-7}}


*[http://www.ch-iv.com/pdfs/Safety%20History%20of%20International%20LNG%20Operations%20_Mar%202009_.pdf Safety History of International LNG Operations, March 2009]
*[http://www.ch-iv.com/pdfs/Safety%20History%20of%20International%20LNG%20Operations%20_Mar%202009_.pdf Safety History of International LNG Operations, March 2009]


Some on-site accidents involving or related to LNG are listed below:
* October 1944: The East Ohio Natural Gas Company experienced a failure of an LNG tank in [[Cleveland|Cleveland, Ohio]].<ref name="CHIV">{{cite paper|title=Safe History of International LNG Operations|url=http://www.ch-iv.com|author=CH-IV|date=December 2006}}</ref> 128 people perished in the [[Cleveland East Ohio Gas explosion|explosion and fire]]. The tank did not have a dike retaining wall, and it was made during World War II, when metal rationing was very strict. The steel of the tank was made with an extremely low amount of [[nickel]], which meant the tank was brittle when exposed to the extreme cold of LNG.  The tank ruptured, spilling LNG into the city sewer system. The LNG vaporized and turned into gas, which exploded and burned.
* October 1979: [[Lusby, Maryland]], at the Cove Point LNG facility a pump seal failed, releasing gas vapors (not LNG), which entered and settled in an electrical conduit.<ref name="CHIV" /> A worker switched off a circuit breaker, igniting the gas vapors, killing a worker, severely injuring another and causing heavy damage to the building. National fire codes were changed as a result of the accident.
* January 2004: [[Skikda]], [[Algeria]]. Explosion at Sonatrach LNG liquefaction facility.<ref name="CHIV" /> 27 killed, 56 injured, three LNG trains destroyed, 2004 production was down 76% for the year. A steam boiler that was part of a liquefaction train exploded triggering a massive hydrocarbon gas explosion. The explosion occurred where propane and ethane refrigeration storage were located.






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Revision as of 13:50, 28 February 2011

In its liquid state, LNG is neither flammable or explosive.[1][2] For LNG to burn, it must first vaporize, then mix with air in the proper proportions (the flammable range is 5 to 15 volume percent[3]), and then be ignited.

When an LNG is released into the atmosphere because of a leak, spill or any other cause (on land or at sea), it immediately begins to vaporize by absorbing heat from the ground or the sea water. At the usual ambient air temperature of about 15 to 40 °C, natural gas is much lighter than air. However, the natural gas vapor formed when LNG vaporizes is very cold (i.e., −160 °C) and therefore much denser than the ambient air. The vapor begins mixing with air and water moisture in the air is condensed to form a visible vapor cloud. . As the cloud is initially formed, it contains too much natural gas to be flammable. The cloud will linger near ground level until further heat is absorbed and the natural gas rises and mixes with more air. As that occurs, the concentration of natural gas within the cloud begins to decrease.. At some point, the natural gas concentration in the cloud will decrease to the point where the gas is in the flammable range and becomes ignitable. If an ignition sources is present at that point, only the part of the cloud which is within the flammable range will burn. The vapor cloud will not explode unless it is confined. Any part of the cloud that enters a building or becomes confined in a congested area will become explosive if encounters an ignition source.[4][5]




  1. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named CalifEnergyCommission
  2. ↑ Frequently Asked Questions: LNG] From the website of the Federal Energy Regulatory Commission
  3. ↑ Note: If there is less than 5 volume % or more than 15 volume % of natural gas vapor in the air, the gas will not burn.
  4. ↑ John M. Woodward and Robin Pitblado (2010). LNG Risk Based Safety: Modeling and Consequence Analysis. John Wiley and American Institute of Chemical Engineers. ISBN 0-470-31764-7. 
  5. ↑ Report On Issues Regarding The Existing New York Liquefied Natural Gas Moratorium 1998, from the website of the New York State Energy and Research Development Authority (NYSERDA). The report concluded that safety concerns associated with LNG terminal facilities were adequately addressed by existing Federal, State and local statutes and regulations. For those reasons, the study recommended: that the New York State Legislature discontinue the existing moratorium.
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