Multiphase equilibrium calculations using a reduction method

Martín, Pablo; Nichita, Dan Vladimir

doi:10.1016/j.fluid.2015.05.006

Cited by 25 publications

(14 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Equation 6remains valid for any reduction procedure (Hendriks and van Bergen, 1992;Nichita, 2006;Nichita and Minescu, 2004), provided appropriate elements of the reduction matrix are used. It is worth noting that equation 6is a key equation for flash calculations using reduction methods (Nichita and Graciaa, 2011;Petitfrere and Nichita, 2015) and for pseudo-component delumping (Nichita and Leibovici, 2006). Expressions for the coefficients C k (k > 2) are given in the Appendix.…”

Section: Asymptotic Behavior Of Equilibrium Ratios and Their Logarithmentioning

confidence: 99%

Application of near critical behavior of equilibrium ratios to phase equilibrium calculations

Nichita¹,

Montel²

2019

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

Self Cite

View full text Add to dashboard Cite

We examine the asymptotic behavior of the equilibrium ratios (Ki) near the convergence locus in the pressure-temperature plane. When the Equation of State (EoS) is analytical, which is the case of most EoS of engineering purpose, Ki tends towards unity or, equivalently, its logarithm lnKi tends to zero, according to a power ½ of the distance to this locus. As a consequence, if lnKi is expressed as a linear combination of pure component parameters with coefficients only depending on mixture phase properties (i.e., reduction parameters), these coefficients obey a similar power law. Deviations from the ½ power law are thus fairly limited for lnKi and for the reduction parameters (at least in the negative flash window between the convergence locus and the phase boundaries), which can be exploited to speed up flash calculations and for quickly determining approximate saturation points and convergence pressures and temperatures. The chosen examples are representative synthetic and natural hydrocarbon mixtures, as well as various injection gas-hydrocarbon systems.

show abstract

Section: Asymptotic Behavior Of Equilibrium Ratios and Their Logarithmentioning

confidence: 99%

Application of near critical behavior of equilibrium ratios to phase equilibrium calculations

Nichita¹,

Montel²

2019

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

Self Cite

View full text Add to dashboard Cite

show abstract

“…We implemented the ILJ reduced variables to three-phase flash calculations that are described in detail in Gorucu (2013). Nichita and Petitfrere (2015) and Petitfrere and Nichita (2015b) recently showed that these reduced variables are unbounded and better scaled. These authors, however, used eigenvalue decomposition, while we used the empirical BIP formula of Li and Johns (2006).…”

Section: Three-phase Flash Calculations Using New Reduced Variablesmentioning

confidence: 99%

“…In their reduced approach the phase behavior predictions were identical between the conventional and reduced methods so that the improvement in robustness was more certain, at least for the fluids studied. Recently, Petitfrere and Nichita (2015b) introduced a new multiphase equilibrium calculation technique using a reduction method which is very similar to our algorithm (Gorucu, 2013). In their paper, they also show that their reduction method is equivalent to an unbounded minimization problem.…”

Section: Introductionmentioning

confidence: 99%

Robustness of three-phase equilibrium calculations

Gorucu¹,

Johns

2016

Journal of Petroleum Science and Engineering

View full text Add to dashboard Cite

Phase equilibrium calculations converge less often as the number of phases and components increase, and for overall compositions closer to phase split boundaries and critical points. Computational speed and robustness of flash calculations are very important aspects for pipeline transmission and for reservoir simulation where billions of flash calculations may be done. Reduced methods have the potential to improve the robustness of phase equilibrium calculations because if chosen properly they can linearize the equations, use fewer independent variables and can be unbounded. Improved robustness could further improve the speed and accuracy of compositional simulation and avoid false two-phase solutions, where three or more phases may be present. In this paper, we use the reduced variables of Gorucu and Johns (2014) to test robustness in performing two-and three-phase stability analysis and corresponding flash calculations. These multiphase equilibrium calculations are compared with the conventional phase equilibrium calculations based on minimization of Gibbs energy and the reduced method proposed by Okuno et. al. (2010a). Using thousands of equally-spaced and unbiased multi-phase equilibrium calculations, the proposed multi-phase equilibrium calculations are shown to be more robust than the other two tested algorithms.

show abstract

“…Use of reduction methods [15,16] and change of the space variable from temperature/pressure to density are just a few [17,18].…”

Section: Introductionmentioning

confidence: 99%

Equations of State with Group Contribution Binary Interaction Parameters for Calculation of Two-Phase Envelopes for Synthetic and Real Natural Gas Mixtures with Heavy Fractions

Nasrifar

Rahmanian

2018

Oil & Gas Science and Technology - Rev. IFP Energies nouvel

View full text Add to dashboard Cite

Three equations of state with a group contribution model for binary interaction parameters were employed to calculate the vapor-liquid equilibria of synthetic and real natural gas mixtures with heavy fractions. In order to estimate the binary interaction parameters, critical temperatures, critical pressures and acentric factors of binary constituents of the mixture are required. The binary interaction parameter model also accounts for temperature. To perform phase equilibrium calculations, the heavy fractions were first discretized into 12 Single Carbon Numbers (SCN) using generalized molecular weights. Then, using the generalized molecular weights and specific gravities, the SCN were characterized. Afterwards, phase equilibrium calculations were performed employing a set of (nc + 1) equations where nc stands for the number of known components plus 12 SCN. The equations were solved iteratively using Newton's method. Predictions indicate that the use of binary interaction parameters for highly sour natural gas mixtures is quite important and must not be avoided. For sweet natural gas mixtures, the use of binary interaction parameters is less remarkable, however.

show abstract

Multiphase equilibrium calculations using a reduction method

Cited by 25 publications

References 44 publications

Application of near critical behavior of equilibrium ratios to phase equilibrium calculations

Application of near critical behavior of equilibrium ratios to phase equilibrium calculations

Robustness of three-phase equilibrium calculations

Equations of State with Group Contribution Binary Interaction Parameters for Calculation of Two-Phase Envelopes for Synthetic and Real Natural Gas Mixtures with Heavy Fractions

Contact Info

Product

Resources

About