VLL Equilibria and Critical End Points Calculation of Nitrogen-Containing LNG Systems: Application of SRK and PC-SAFT Equations of State

Ramírez-Jiménez, Edgar; Justo-García, Daimler N.; García-Sánchez, Fernando; Stateva, Roumiana P.

doi:10.1021/ie300372a

Cited by 5 publications

(5 citation statements)

References 31 publications

(77 reference statements)

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“…Since the load of compressors is greatly influenced by the vaporized gas of tanks, an appropriate equation of state is necessary for the sufficiently accurate description of the BOG. Considering that BOG is primarily composed of methane and nitrogen, the Soave-Redlich-Kwong (SRK) equation is used to describe the gas phase in the tank, which is calculated as follows [43,44]:…”

Section: Modeling the Backup Compressorsmentioning

confidence: 99%

MINLP Model for Operational Optimization of LNG Terminals

Xiaoyan

Zhao

2021

Processes

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Liquefied natural gas (LNG) is a clear and promising fossil fuel which emits less greenhouse gas (GHG) and has almost no environmentally damaging sulfur dioxide compared with other fossil fuels. An LNG import terminal is a facility that regasifies LNG into natural gas, which is supplied to industrial and residential users. Modeling and optimization of the LNG terminals may reduce energy consumption and GHG emission. A mixed-integer nonlinear programming model of the LNG terminal is developed to minimize the energy consumption, where the numbers of boil-off gas (BOG) compressors and low-pressure (LP) pumps are considered as integer variables. A case study from an actual LNG terminal is carried out to verify the practicality of the proposed method. Results show that the proposed approach can decrease the operating energy consumption from 9.15% to 26.1% for different seasons.

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Section: Modeling the Backup Compressorsmentioning

confidence: 99%

MINLP Model for Operational Optimization of LNG Terminals

Xiaoyan

Zhao

2021

Processes

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“…The most straightforward inter-phases equilibrium, of a N 2 -CH 4 -C 2 H 6 ternary system, is a liquid-vapor equilibrium (LVE). However, liquid-liquid-vapor equilibria (LLVE) do occur under certain conditions in ternary and liquefied natural gas (LNG) systems, including liquid phase inversion 12 . LLVE equilibria consist in the coexistence of two liquids, of different compositions, with a vapor.…”

Section: Existence Of Liquid-liquid-vapor Equilibria For Hydrocarbon mentioning

confidence: 99%

“…The number of phases is then increased by one, and equilibrium is reached by minimizing the Gibbs energy. The procedure is continued until a stable solution is found 12 . This approach has been validated by comparison with many laboratory measurements involving ternary mixtures.…”

Section: Implication For Titanmentioning

confidence: 99%

“…LLVE equilibria consist in the coexistence of two liquids, of different compositions, with a vapor. In the laboratory, LLVEs have been observed for systems, under cryogenic conditions, comparable to Titan's liquid phases: nitrogen + methane + (ethane, or propane, or n-butane) [12][13][14][15][16] . At the Huygens landsite, i.e.…”

Section: Existence Of Liquid-liquid-vapor Equilibria For Hydrocarbon ...mentioning

confidence: 99%

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Bubble streams in Titan’s seas as a product of liquid N2 + CH4 + C2H6 cryogenic mixture

et al. 2017

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Titan, Saturn's largest moon, is the only extraterrestrial body known to support stable liquid on its surface, in the form of seas and lakes that dot the polar regions. Many indications suggest that the liquid should be composed of a mixture of N 2 , CH 4 and C 2 H 6 . Recent RADAR observations of Titan's large sea, called "Ligeia Mare", have shown unexplained and ephemeral bright features, possibly due to rising bubbles. Here we report that our numerical model, when combined with experimental data found in the literature, shows that Ligeia Mare's bed is a favourable place for nitrogen exsolution. This process could produce centimeter-sized and radar-detectable bubbles.

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“…Figure 6 presents the critical points for the binary mixture of nitrogen and ethane. The value of the one-fluid SRK mixture model interaction parameter k ij = 0.0407 is taken from Ramírez-Jiménez et al [53]. This mixture is of interest because even though the constituent fluids are simple molecules, and form a relatively symmetric mixture, it is still possible to yield interesting critical point behavior.…”

Section: While Tracing the L *mentioning

confidence: 99%

Calculation of critical points from Helmholtz-energy-explicit mixture models

Bell

Jäger

2017

Fluid Phase Equilibria

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The calculation of the critical points for a mixture of fluids is of practical interest as the calculated critical points can be used to more reliably and efficiently construct phase envelopes. The number of stable critical points found can also provide insight into whether the mixture has an open or closed phase envelope. In this work we have developed a reliable method for determining all the critical points for a mixture that is modeled with Helmholtz-energy-explicit equations of state. This method extends the algorithms developed in the literature for simpler equations of state to these more complex mixture models. These Helmholtz-energyexplicit equations of state could be either multi-fluid models or transformations of simple cubic equations of state to Helmholtz-energy-explicit forms. This algorithm locks onto the first criticality contour (the spinodal) and traces it to high density, thereby locating all relevant critical points. The necessary analytic derivatives of the residual Helmholtz energy, numerically validated values of the derivatives for validation, sample code, and additional figures and information are provided in the supplemental material. * Commercial equipment, instruments, or materials are identified only in order to adequately specify certain procedures. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the products identified are necessarily the best available for the purpose.

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VLL Equilibria and Critical End Points Calculation of Nitrogen-Containing LNG Systems: Application of SRK and PC-SAFT Equations of State

Cited by 5 publications

References 31 publications

MINLP Model for Operational Optimization of LNG Terminals

MINLP Model for Operational Optimization of LNG Terminals

Bubble streams in Titan’s seas as a product of liquid N2 + CH4 + C2H6 cryogenic mixture

Calculation of critical points from Helmholtz-energy-explicit mixture models

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