A Robust Three-Phase Isenthalpic Flash Algorithm Based on Free-Water Assumption

2017 ◽  
Author(s):  
Ruixue Li ◽  
Huazhou Andy Li
Keyword(s):  
Phase Equilibria ◽  
Free Water ◽  
Conservation Equation ◽  
Feed Mixture ◽  
Outer Loop ◽  
Two Phase ◽  
Hydrocarbon Mixtures ◽  
Energy Conservation Equation ◽  
Three Phase ◽  
Vapor Liquid

Multiphase isenthalpic flash calculations are often required in compositional simulations of steam-based enhanced oil recovery methods. These flash calculations are challenging in the narrow-boiling regions and in the determination of the correct number of existing phases. Based on the free-water assumption that the aqueous phase is pure water, a robust and efficient algorithm is proposed to perform isenthalpic three-phase flash calculations in this work. Multiphase equilibria can be considered by this algorithm, including single-phase equilibria, two-phase equilibria, and three-phase vapor-liquid-aqueous equilibria. Isenthalpic flash is a type of flash calculation conducted at given pressure and enthalpy for a feed mixture. In the proposed algorithm, assuming the feed is stable, the temperature is first determined by solving the energy conservation equation. Then the stability test on the feed mixture is conducted at the calculated temperature and the given pressure. If the mixture is found unstable, the two-phase and three-phase vapor-liquid-aqueous isenthalpic flash calculations can be simultaneously initiated without resorting to stability tests. To achieve simultaneous flashes, the outer loop is used to update the temperature by solving the energy conservation equation. The inner loop is used to obtain phase fractions and compositions by performing a three-phase free-water isothermal flash. Note that a two-phase isothermal flash will be initiated if an open feasible region in the phase fractions appears in any iteration during the three-phase isothermal flash or any of the ultimately calculated phase fractions from the three-phase flash do not belong to [0,1]. Negative flash is allowed in the three-phase free-water isothermal flash. A number of example calculations for water/hydrocarbon mixtures are carried out to test the robustness of the proposed algorithm. At low to medium pressures, a good agreement can be achieved between the results obtained by this algorithm and those obtained by the conventional algorithm. This algorithm performs well for the narrow-boiling regions, for example, the three-phase vapor-liquid-aqueous equilibrium region encountered for the water/hydrocarbon mixtures. During the iteration, the new algorithm can readily handle the appearance and disappearance of phases in the inner loop as temperature updates in the outer loop. The number of stability tests involved in the new algorithm is significantly reduced, helping to boost its computational efficiency.

A Robust Three-Phase Isenthalpic Flash Algorithm Based on Free-Water Assumption

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Ruixue Li ◽  
Huazhou Andy Li
Keyword(s):  
Energy Conservation ◽  
Oil Recovery ◽  
Pure Water ◽  
Free Water ◽  
Conservation Equation ◽  
Feasible Region ◽  
Feed Mixture ◽  
Two Phase ◽  
Energy Conservation Equation ◽  
Three Phase

Isenthalpic flash is a type of flash calculation conducted at a given pressure and enthalpy for a feed mixture. Multiphase isenthalpic flash calculations are often required in compositional simulations of steam-based enhanced oil recovery methods. Based on a free-water assumption that the aqueous phase is pure water, a robust and efficient algorithm is developed to perform isenthalpic three-phase flashes. Assuming that the feed is stable, we first determine the temperature by solving the energy conservation equation. Then, the stability test on the feed mixture is conducted at the calculated temperature and the given pressure. If the mixture is found unstable, two-phase and three-phase vapor–liquid–aqueous isenthalpic flash can be simultaneously initiated without resorting to stability tests. The outer loop is used to update the temperature by solving the energy conservation equation. The inner loop determines the phase fractions and compositions through a three-phase free-water isothermal flash. A two-phase isothermal flash will be initiated if an open feasible region in the phase fractions appears in any iteration during the three-phase flash or any of the ultimately calculated phase fractions from the three-phase flash do not belong to [0,1]. A number of example calculations for water/hydrocarbon mixtures are carried out, demonstrating that the proposed algorithm is accurate, efficient, and robust.

scholarly journals Thermodynamics and Machine Learning Based Approaches for Vapor–Liquid–Liquid Phase Equilibria in n-Octane/Water, as a Naphtha–Water Surrogate in Water Blends

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 413
Author(s):  
Sandra Lopez-Zamora ◽  
Jeonghoon Kong ◽  
Salvador Escobedo ◽  
Hugo de Lasa
Keyword(s):  
Machine Learning ◽  
Liquid Phase ◽  
Phase Equilibria ◽  
Aspen Plus ◽  
Phase Region ◽  
Two Phase ◽  
Technical Literature ◽  
Phase Liquid ◽  
Liquid Vapor ◽  
Vapor Liquid

The prediction of phase equilibria for hydrocarbon/water blends in separators, is a subject of considerable importance for chemical processes. Despite its relevance, there are still pending questions. Among them, is the prediction of the correct number of phases. While a stability analysis using the Gibbs Free Energy of mixing and the NRTL model, provide a good understanding with calculation issues, when using HYSYS V9 and Aspen Plus V9 software, this shows that significant phase equilibrium uncertainties still exist. To clarify these matters, n-octane and water blends, are good surrogates of naphtha/water mixtures. Runs were developed in a CREC vapor–liquid (VL_ Cell operated with octane–water mixtures under dynamic conditions and used to establish the two-phase (liquid–vapor) and three phase (liquid–liquid–vapor) domains. Results obtained demonstrate that the two phase region (full solubility in the liquid phase) of n-octane in water at 100 °C is in the 10-4 mol fraction range, and it is larger than the 10-5 mol fraction predicted by Aspen Plus and the 10-7 mol fraction reported in the technical literature. Furthermore, and to provide an effective and accurate method for predicting the number of phases, a machine learning (ML) technique was implemented and successfully demonstrated, in the present study.

Flow of High Prandtl Number Fluid under Varying Axial Magnetic Field

2012 ◽  
Vol 256-259 ◽  
pp. 2412-2415
Author(s):  
Ru Quan Liang ◽  
Shuo Yang ◽  
Jun Hong Ji ◽  
Ji Cheng He
Keyword(s):  
Magnetic Field ◽  
Stokes Equations ◽  
Axial Magnetic Field ◽  
Internal Flow ◽  
Conservation Equation ◽  
Staggered Grid ◽  
Zone Method ◽  
Two Phase ◽  
Energy Conservation Equation ◽  
Structure Of Flow

From engineering actual conditions of single crystal grown by floating zone method, Navier-Stokes equations coupled with the energy conservation equation were solved on a staggered grid based on the half floating area physical model. The two-phase surface was captured by using the mass conserving level set method. The internal flow structure of flow field of high Pr number liquid bridge was studied under uniform magnetic field environment in microgravity, which is important to optimize the process of the crystal growth.

Influence of Vertical Vibration on Surface Velocity of a Liquid Bridge

2014 ◽  
Vol 580-583 ◽  
pp. 2890-2893
Author(s):  
Ru Quan Liang ◽  
Zhi Hui Zhang ◽  
Tai Yin Gao ◽  
Fu Sheng Yan
Keyword(s):  
Liquid Bridge ◽  
Stokes Equations ◽  
Silicone Oil ◽  
Conservation Equation ◽  
Vertical Vibration ◽  
Surface Velocity ◽  
Staggered Grid ◽  
Navier Stokes ◽  
Two Phase ◽  
Energy Conservation Equation

In this paper, the vertical vibration influence on the surface velocity of a 5cSt silicone oil liquid bridge has been investigated numerically. The Navier-Stokes equations coupled with the energy conservation equation are solved on a staggered grid, and the two-phase surface is captured by using the mass conserving level set method. The present results indicate that the axial and radial surface velocities of the liquid bridge are suppressed by the external vertical vibration.

Phase Equilibria among γ-Fe, γ-Fe and Fe2Mo Phases and Stability of the Laves Phase in Fe-Mo-Ni Ternary System at Elevated Temperatures

2006 ◽  
Vol 980 ◽  
Author(s):  
Shigehiro Ishikawa ◽  
Takashi Matsuo ◽  
Masao Takeyama
Keyword(s):  
Ternary System ◽  
Phase Equilibria ◽  
Elevated Temperatures ◽  
Phase Region ◽  
Homogeneity Region ◽  
Nickel Concentration ◽  
Peritectoid Reaction ◽  
Two Phase ◽  
Three Phase ◽  
Binary Edge

AbstractPhase equilibria among the bcc Fe(α), fcc Fe(γ) and Fe2Mo(λ)_phases in Fe-Mo-Ni ternary system, particularly paying attention to the existence of the γ+λ two-phase region, have been examined at elevated temperatures below Tc (1200 K), the peritectoid reaction temperature in Fe-Mo binary system: λ?α+Fe7Mo6 (μ). At 1173 K the α+γ+μ three-phase coexisting region exists near the Fe-Mo binary edge and no λ phase region was identified. At 1073 K the λ phase in equilibrium with α and γ phases exists, although the composition homogeneity region of the ternary λ phase was limited to its binary edge toward the equi-nickel concentration direction up to about 3at % Ni. Instead, large two-phase region of γ+μ was extended along the same direction up to 20 at% Ni. The γ+λ two-phase region appears below Tc through a transition peritectoid reaction: α+μ¨γ+λ. The γ phase in equilibrium with λ phase is stable only at elevated temperatures, and it transforms martensitically to α phase during cooling. The addition of Ni stabilizes γ and μ phases against α and λ phases, thereby decreasing the relative stability of the λ phase.

Phase Equilibria in the Er-Cu-V and Dy-Cu-V at 773K

2013 ◽  
Vol 815 ◽  
pp. 3-7
Author(s):  
Shi Ping Guo ◽  
Wei He ◽  
Yun Hong Zhao ◽  
Ling Min Zeng
Keyword(s):  
Isothermal Section ◽  
Phase Equilibria ◽  
Ternary Compound ◽  
Single Phase ◽  
Ternary Systems ◽  
Two Phase ◽  
Isothermal Sections ◽  
Three Phase ◽  
Binary Compounds

The isothermal sections of the Er-Cu-V and Dy-Cu-V ternary systems at 773K were investigated by experiments. The isothermal section of Er-Cu-V consists of 8 single-phase regions, 13 two-phase regions and 6 three-phase regions. The binary compounds ErCu5, ErCu2, ErCu, Er2Cu9and Er2Cu7were observed at 773K. The isothermal section of Dy-Cu-V consists of 7 single-phase regions, 11 two-phase regions and 5 three-phase regions. The binary compounds DyCu5, DyCu2, DyCu and Dy2Cu9were confirmed at 773K. No ternary compound was found in the two sections. There is no solubility of V in the Er-Cu and Dy-Cu binary compounds observed.

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