Thermodynamic modelling of acid gas removal from natural gas using the Extended UNIQUAC model

Sadegh, Negar; Stenby, Erling Halfdan; Thomsen, Kaj

doi:10.1016/j.fluid.2017.02.020

Cited by 19 publications

(7 citation statements)

References 15 publications

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“…In the EUQ model, the activity coefficients (γ) are given by the sum of three terms: combinatorial, residual, and Debye–Hückel terms. − ,, The combinatorial term (γ i C ), which corrects the departure from the ideal solution taking into account the shape and size of an ion, is a function of the mole fractions ( x ), as expressed by where r and q are the volume and surface area parameters in the system, and z is the coordination number, which is normally set to 10.…”

Section: Results and Discussionmentioning

confidence: 99%

“…The EUQ model has been extensively employed to reproduce the phase diagrams of various systems including liquid–gas, ,, liquid–solid, ,− , and liquid–liquid systems. − A number of combinations of parameters have been evaluated in terms of the agreements of experimental data with calculated phase behaviors. ,, In this study, the parameters listed in Tables S1 and S2 were used to predict the behavior of the components of phosphate buffers using the EUQ model. The binary phase diagrams of water and one of the phosphate salts were first studied to validate the present calculations.…”

Section: Results and Discussionmentioning

confidence: 99%

“…However, the EUQ model has been applied to the explanation of the freezing behavior of aqueous electrolytes and has provided relatively good predictions. An advantage of this approach is that it requires fewer parameters than other equivalent models. − In this method, the original universal quasichemical model is combined with long-range interactions of ions to reasonably represent aqueous electrolyte solutions. Christensen and Thomsen have interpreted the solid–liquid equilibria of phosphate buffers using this model.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Quasichemical Approach to pH Shifts in Frozen Phosphate Buffers

Okada

Uyama²,

Harada

et al. 2019

Ind. Eng. Chem. Res.

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Shifts in the pH of buffer solutions upon freezing have received much attention particularly in the life sciences, as such pH variations during freezing may damage biological samples, biomolecules, and pharmaceuticals. The understanding and prediction of the said pH changes upon freezing are essential to utilize buffer solutions in a wide temperature range, including subzero temperatures. Phosphate is of particular importance for aqueous buffer preparation as it covers a wide pH range and displays high biocompatibility. However, the phase behavior and pH changes in phosphate buffers at subzero temperatures are very complex due to the variety of species involved in the phase and acid–base equilibria. This paper focuses on the interpretation of the pH changes in phosphate buffers under freezing conditions using an extended universal quasichemical (EUQ) model. This model has been previously applied to understand the phase behavior (solid precipitation) in phosphate buffers at subzero temperatures but not to the calculation of the pH of the liquid phase (freeze-concentrated solution, FCS) that coexists with ice and salt precipitate. Since the EUQ model provides activity coefficients for all of the components in the system, not only the phase behavior but also the pH value can be estimated. The calculated pH values are compared to experimental values and are interpreted from the viewpoints of salt deposition, salt enrichment in the FCS, and supercooling effects.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Quasichemical Approach to pH Shifts in Frozen Phosphate Buffers

Okada

Uyama²,

Harada

et al. 2019

Ind. Eng. Chem. Res.

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“…The choice of appropriate thermodynamic models and the accuracy of parameters are crucial for the reliability of the design. Acid Gas-Chemical Solvent was used as the property package for acid gas removal process [25,26].…”

Section: Process Descriptionmentioning

confidence: 99%

Techno-Economic Analysis of a Novel Two-Stage Flashing Process for Acid Gas Removal from Natural Gas

et al. 2019

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Excessive CO2 content will reduce the natural gas calorific value and increase the energy consumption of the regenerator in natural gas desulfurization and decarbonization. This paper uses Aspen HYSYS to model a novel two-stage flash process of acid gas removal process from natural gas. According to the results from the simulation, as well as running experiences in a natural gas processing plant in the middle east, it can be demonstrated that this new process, which has been used in the field of natural gas desulfurization and decarbonization, can meet the requirement of product specifications. Based on the steady state simulation, Aspen HYSYS sensitivity function is used to evaluate influence of key operating parameters, such as the second flash pressure and temperature, on the energy consumption. Compared to the traditional acid gas removal process and acid gas enrichment process, the new two-stage flash acid gas removal process has less energy consumption (2.2 × 109 kJ·h−1). In addition, two-stage flash acid gas removal process also improves the efficiency of acid gas enrichment, while the overall energy consumption is less than combination process of traditional process and acid gas enrichment process.

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“…Generally, these frameworks can be divided into activity coefficient models and equations of state (EOS). Activity coefficient models regress the reacting system and have been used early on. − Beneficially, these models are easy to use; however, they usually require a huge number of adjustable parameters, i.e., they are highly correlative. In the last decade, EOS have been favored to model phase behavior for absorption processes.…”

Section: Introductionmentioning

confidence: 99%

Predicting Vapor–Liquid Equilibria for Sour-Gas Absorption in Aqueous Mixtures of Chemical and Physical Solvents or Ionic Liquids with ePC-SAFT

Bülow

Ince²,

Hirohama³

et al. 2021

Ind. Eng. Chem. Res.

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Sour-gas absorption is the main unit operation used in refineries and petrochemical and natural gas processing plants for the effective reduction of climate-wrecking gases, mainly CO 2 and H 2 S. Absorption is typically accomplished in an aqueous solvent mixture. The solvent mixture is vastly dependent on the application range; it might contain chemical solvents (amines), activators, and physical solvents. In this work, the vapor−liquid equilibria for absorption of the sour gases CO 2 and H 2 S was investigated in systems containing the chemical solvent methyl diethanolamine (MDEA) and the physical solvents tetrahydrothiophene-1,1-dioxide (sulfolane) or the ionic liquid 1-butyl-3-methylimidazolium acetate. The solubilities of CO 2 and H 2 S were predicted and validated using experimental literature data in a broad range of temperature (313−373 K), sour-gas loading (up to 2 moles gas per moles of MDEA), and pressure (up to 180 bar) at constant MDEA weight fraction (20.9 wt %) and sulfolane weight fraction (30.5 wt %). The equation-of-state electrolyte perturbed-chain statistical associating fluid theory (ePC-SAFT) was utilized in this work for the predictions combined with the Born term to physically correctly describe the Gibbs energy of solvation of ions in the aqueous mixture of chemical and physical solvents; this was introduced in a recent work [Bulow, M. et al. Fluid Phase Equilib. 2021, 535, 112967]. Using this approach allowed reducing the total number of binary interaction parameters in these systems of maximum 11 species to a minimum; these parameters were fitted exclusively to data of binary mixtures. The ePC-SAFT predictions of the gas solubility were most accurate at low sour-gas loadings and high temperatures. This work provides a thermodynamic framework for the solvent selection for sour-gas absorption in a broad range of conditions. This enables a realistic decrease in experimental effort for solvent selection in sour-gas absorption.

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Thermodynamic modelling of acid gas removal from natural gas using the Extended UNIQUAC model

Cited by 19 publications

References 15 publications

Quasichemical Approach to pH Shifts in Frozen Phosphate Buffers

Quasichemical Approach to pH Shifts in Frozen Phosphate Buffers

Techno-Economic Analysis of a Novel Two-Stage Flashing Process for Acid Gas Removal from Natural Gas

Predicting Vapor–Liquid Equilibria for Sour-Gas Absorption in Aqueous Mixtures of Chemical and Physical Solvents or Ionic Liquids with ePC-SAFT

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