Predicting the Phase Equilibria of Carbon Dioxide Containing Mixtures Involved in CCS Processes Using the PPR78 Model

Privat, Romain; Jaubert, Jean‐Noël

doi:10.5772/57058

Cited by 10 publications

(10 citation statements)

References 18 publications

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“…In Aspen HYSYS, the equilibrium models SRK (Soave, 1972), PR (Peng and Robinson, 1976) and TST (Twu et al, 2005) are available for systems containing methane, CO2 and water. In the SRK-Twu and PR-Twu models, the original α-function is replaced by a function from Twu et al (1991).…”

Section: Simulation Programs and Modelsmentioning

confidence: 99%

“…Traditionally, gas mixtures of methane, CO2 and water are calculated in a process simulation program with standard models like PR (Peng and Robinson, 1976) and SRK (Soave, 1972). It is known that these models simulate the gas phase and the condensation point quite accurately at least below the critical point (46 bar for methane and 74 bar for CO2), but the resulting liquid phase may be questionable.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of Condensation in Compressed Raw Biogas Using Aspen HYSYS

Øi¹,

Hovland²

2018

Linköping Electronic Conference Proceedings

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Raw biogas typically contains 60 % methane, 40 % CO2, small amounts of other components and is saturated with water. It is a question whether raw biogas can be compressed to high pressures without condensation. The aim of this work is to calculate the condensation limit under different conditions with varied temperature, pressure and gas composition using different equilibrium models. Traditionally, gas mixtures of methane, CO2 and water are calculated in a process simulation program with standard models like Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK). PR and SRK with the α-function replaced with a Twu αfunction were also evaluated. For mixtures with only methane and CO2 (dry biogas) all the models gave similar results. Under normal ambient temperatures (above 0 °C), a dry mixture with more than 40 % methane will not give any condensation. For biogas saturated with water, the different models gave similar results up to about 70 bar when binary coefficients were included, but above this pressure there were significant deviations between the models. The PR and SRK with standard or Twu α-function gave reasonable results for the dew-point predictions, but above about 70 bar the uncertainty increases.

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Section: Simulation Programs and Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simulation of Condensation in Compressed Raw Biogas Using Aspen HYSYS

Øi¹,

Hovland²

2018

Linköping Electronic Conference Proceedings

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“…For the other systems, the computed BIPs are in agreement with BIPs used in Aspen Plus. Note that BIPs are typically temperature dependent [53][54][55], but Aspen Plus uses a temperature independent BIP for the investigated gas mixtures, which complicates a direct comparison with our results.…”

Section: Binary Systems and Binary Interaction Parametersmentioning

confidence: 99%

Computing equation of state parameters of gases from Monte Carlo simulations

Ramdin

Becker

Jamali

et al. 2016

Fluid Phase Equilibria

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Monte Carlo (MC) simulations in ensembles with a fixed chemical potential or fugacity, for example the grand-canonical or the osmotic ensemble, are often used to compute phase equilibria. Chemical potentials can be computed either with an equation of state (EoS) or from molecular simulations. The accuracy of the computed chemical potentials depends on the quality of the (critical) parameters used in the EoS and the applied force field in the simulations. We investigated the consistency of both approaches for computing fugacities of the industrially relevant gases CO 2 , CH 4 , CO, H 2 , N 2 , and H 2 S. The critical temperature (T c), pressure (P c), and acentric factors (ω) of these gases are computed from MC simulations in the Gibbs ensemble. The effect of cutoff radius and tail corrections on the computed values of T c , P c , and ω is investigated. In addition, MC simulations in the Gibbs ensemble are used to compute the VLE of the 15 possible binary systems comprising the gases CO 2 , CH 4 , CO, H 2 , N 2 , and H 2 S, and the ternary systems CO 2 /CH 4 /H 2 S and CO 2 /CO/H 2. Binary interaction parameters (k ij) of these natural/synthesis gas mixtures are obtained by fitting the Peng-Robinson (PR) EoS to the binary VLE data from the MC simulations. The computed properties from the MC simulations are compared with the PR EoS, the GERG EoS, and experimental results. The MC results show that including tail corrections in the simulations is crucial to obtain accurate critical properties. The force fields used for the gases can reproduce the fugacities of the gases within 5% of

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“…Gas mixtures of methane, CO2 and water are calculated in a process simulation program with standard models like PR (Peng and Robinson, 1976) and SRK (Soave, 1972).…”

Section: Introductionmentioning

confidence: 99%

“…There is a limited number of articles available studying the calculations and models for vapour/liquid equilibrium in the methane/CO2/water-system (Austegard et al, 2006;Privat and Jaubert, 2014;Al Ghafri et al, 2014;Legoix et al, 2017). Austegard et al conclude that a simple equation of state like SRK is satisfactory to describe the vapour phase, but more complex models, e.g., SRK combined with a HV model is necessary to describe the liquid phase (Austegard et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Simulation of Dew Points in Raw Biogas Using PR and SRK Equations of State

Bråthen¹,

Øi²,

Hovland³

2020

Linköping Electronic Conference Proceedings

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Biogas contains mainly methane, but raw biogas can contain large amounts of CO2 and is normally saturated with water. Condensation, especially during compression, may lead to operational problems. The aim of this work is to calculate the dew point (condensation limit) under different conditions with different models in the simulation programs Aspen HYSYS and Aspen Plus. Binary coefficients for water and CO2 in these models will be fitted to experimental data from the literature. Traditionally, gas mixtures of methane, CO2 and water are calculated with standard models like Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK). For dry biogas (mixtures with only methane and CO2) all the models give similar results. For a biogas mixture with 60 mol-% methane and 40 mol-% CO2 with 0.1 mol-% added water, the models using binary coefficients fitted for binary mixtures (especially for CO2 and water), gave reasonable results up to about 70 bar, with deviations in the calculated dew point up to 8 K. The binary coefficient for water and CO2 was fitted to experimental data from the literature for a mixture with a CH4 to CO2 molar ratio of 30/70, 50/50 and 70/30. The fitted kij values for the PR model were 0.65, 0.21 and 0.17, respectively. For the SRK model, the kij values were slightly higher. At pressures below 70 bar and temperatures below 40 °C, the uncertainty for calculated dewpoints in mixtures with 30 to 100 % CH4 was reduced to less than 4 K.

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Predicting the Phase Equilibria of Carbon Dioxide Containing Mixtures Involved in CCS Processes Using the PPR78 Model

Cited by 10 publications

References 18 publications

Simulation of Condensation in Compressed Raw Biogas Using Aspen HYSYS

Simulation of Condensation in Compressed Raw Biogas Using Aspen HYSYS

Computing equation of state parameters of gases from Monte Carlo simulations

Simulation of Dew Points in Raw Biogas Using PR and SRK Equations of State

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