Evaluating Crystallization Risks in Liquefied-Natural-Gas (LNG) Production
- Luis F. Ayala (Pennsylvania State University) | Juan Emilio Fernandez (Pennsylvania State University)
- Document ID
- Society of Petroleum Engineers
- SPE Projects, Facilities & Construction
- Publication Date
- June 2009
- Document Type
- Journal Paper
- 27 - 31
- 2009. Society of Petroleum Engineers
- 4.1.1 Process Simulation, 4.6.2 Liquified Natural Gas (LNG), 5.2.1 Phase Behavior and PVT Measurements, 5.3.2 Multiphase Flow, 4.3.3 Aspaltenes, 4.1.4 Gas Processing, 7.4.3 Market analysis /supply and demand forecasting/pricing, 4.3.4 Scale, 1.8 Formation Damage, 4.2 Pipelines, Flowlines and Risers, 4.6 Natural Gas, 5.2.2 Fluid Modeling, Equations of State, 5.5 Reservoir Simulation
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- 456 since 2007
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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.
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).
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