Summary
Liquefied natural gas (LNG) is anticipated to dominate world energy trade
and fill the gap between production and energy demands in a few years,
especially in the US. LNG is the liquefied version of dry natural gases at
ultralow temperatures (approximately -160ºC or -260ºF at atmospheric pressure),
which aims at minimizing storage volume requirements needed for overseas
transportation. Within this context, it is clear that technology must continue
to be developed to optimize the thermodynamic processes involved in the
compression, liquefaction, and revaporization of LNG and associated operational
challenges. One key challenge during the production of LNG is the presence of
trace amounts of heavy components in the gas feed composition is known to
induce the precipitation of a solid phase during the cooling process, which
presents the risk of equipment plugging and associated hazards. However, there
are very few general thermodynamic tools available for the prediction of
solid-liquid equilibrium for very low-temperature conditions (< 200ºF). In
this study, available thermodynamic predictive tools are evaluated for the
determination of LNG crystallization conditions. Previously presented
crystallization prediction models are examined, and potential pitfalls
identified. The results from this study are expected to provide a better
understanding of the thermodynamics of LNG processes and provide a framework
for subsequent work in the analysis of LNG refrigeration and liquefaction
processes--typically considered the key elements of any LNG project.
Introduction
Imported natural gas is expected to play a dominant role in meeting the
projected rise of natural gas consumption during the coming decade in many
industrialized countries. Traditional pipeline transportation is not a viable
method for transoceanic delivery of natural gas supplies and thus, LNG becomes
the method of choice for their marketing. The world market for LNG is
anticipated to become extremely competitive in a few years, with the US not the
only nation set on increasing LNG imports. To close the gap between domestic
production and demand, dependence on LNG imports plays a greater factor on a
worldwide scale, which requires greater infrastructure for LNG capacity,
including expansion of existing terminals and the construction of new
facilities. Within this context, it is clear that technology must continue to
be developed to optimize the thermodynamic processes involved in the
compression, liquefaction, and revaporization of LNG and associated operational
challenges. Proper combination of good engineering design, operation, and
maintenance is what allows handling and producing LNG safely (West and Chiu
2005; Alderman 1972).
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
2 August 2007
- Meeting paper published:
11 November 2007
- Revised manuscript received:
14 September 2008
- Manuscript approved:
30 September 2008
- Published online:
1 June 2009
- Version of record:
1 June 2009
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