The isoenergetic-isochoric flash

Saha, Sanjoy Kumar; Carroll, John J.

doi:10.1016/s0378-3812(97)00151-9

Cited by 41 publications

(24 citation statements)

References 4 publications

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“…Furthermore, Gopal and Biegler (1997) assume perfect pressure control and specify the temperature trajectory in the drum, what results in a much simpler version of the dynamic flash problem. The articles of Saha and Carroll (1997) and Michelsen (1999) are based on UVN flash formulations that use nested-loops since pressure is an iteration variable. This has the disadvantage of requiring the solution of the EOS to obtain the molar volume of each phase in every iteration.…”

Section: Introductionmentioning

confidence: 99%

Dynamic simulation of flash drums using rigorous physical property calculations

Goncalves

Castier

Araújo

2007

Braz. J. Chem. Eng.

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-The dynamics of flash drums is simulated using a formulation adequate for phase modeling with equations of state (EOS). The energy and mass balances are written as differential equations for the internal energy and the number of moles of each species. The algebraic equations of the model, solved at each time step, are those of a flash with specified internal energy, volume and mole numbers (UVN flash). A new aspect of our dynamic simulations is the use of direct iterations in phase volumes (instead of pressure) for solving the algebraic equations. It was also found that an iterative procedure previously suggested in the literature for UVN flashes becomes unreliable close to phase boundaries and a new alternative is proposed. Another unusual aspect of this work is that the model expressions, including the physical properties and their analytical derivatives, were quickly implemented using computer algebra.

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Section: Introductionmentioning

confidence: 99%

Dynamic simulation of flash drums using rigorous physical property calculations

Goncalves

Castier

Araújo

2007

Braz. J. Chem. Eng.

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“…This first example [3] consists in filling a vessel with pure nitrogen. The vessel has inlet and outlet connections.…”

Section: Examplementioning

confidence: 99%

“…Therefore, it is interesting to develop a framework that can be used to simulate the dynamics of separation vessels with phases modeled by EOS. Few papers on vessel dynamics discuss the use of EOS [3][4][5]. This is by no means a trivial extension of dynamic models based on simpler assumptions about phase behavior because: -vapor-liquid equilibrium calculations tend to be more difficult at high pressures than at low pressures, because of the larger departure from ideal phase behavior and the proximity of the mixture critical point; -depending on calculation algorithm and problem specifications, it may be necessary to solve the equation of state to find the molar volume at a given condition of temperature, pressure and system composition.…”

Section: Introductionmentioning

confidence: 99%

Differential-Algebraic Approach to Dynamic Simulations of Flash Drums with Rigorous Evaluation of Physical Properties

Lima

Castier

Biscaia

2008

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Simulation dynamique de séparateurs de mélanges liquide-vapeur avec une approche différentielle algébrique et évaluation rigoureuse des propriétés physiques -La dynamique de séparateurs de mélanges liquide-vapeur est simulé avec des propriétés physiques rigoureusement calculées en utilisant une équation d'état pour modéliser chaque phase. La formulation fournit un ensemble d'équations différentielles algébriques (DAE), dont les équations différentielles décrivent les bilans matérielles et énergétiques et les équations algébriques décrivent les conditions d'équilibre à l'intérieur du séparateur. PSIDE (Parallel Software for Implicit Differential Equations) [Lioen et al., 1998] est utilisé pour résoudre l'ensemble des DAE avec efficacité. Dans cette approche, les équations sont résolues simultanément, avec des itérations directes de température, de volumes de phase et de nombre de moles de chaque composant dans chaque phase. Les résultats montrent l'efficacité de cette méthode de simulation des séparateurs de mélanges liquide-vapeur. [Lioen et al., 1998] Abstract -Differential-Algebraic Approach to Dynamic Simulations of Flash Drums with Rigorous Evaluation of Physical Properties -The dynamics of flash drums is simulated with rigorous physical properties calculations using an equation of state to model each phase present. The formulation results in a set of differential-algebraic equations (DAE), whose differential equations describe the material and energy balances and the algebraic equations result from the conditions for thermodynamic equilibrium inside the drum. PSIDE (Parallel Software for Implicit Differential Equations)

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“…It is usual to avoid numerical entropy maximization because the EOS normally used for chemical process design give thermodynamic properties as explicit functions of temperature (instead of internal energy), volume, and number of moles. Saha and Carroll [11] simulated vessel dynamics with equations of state using an algorithm with nested loops to solve the algebraic phase equilibrium equations. Gonçalves et al [12] used a single loop approach to solve the algebraic equations based on a reformulation of the UVn flash equations using a framework originally proposed by Michelsen [13].…”

Section: Introductionmentioning

confidence: 99%

Dynamic simulation of fluids in vessels via entropy maximization

Castier

2010

Journal of Industrial and Engineering Chemistry

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The isoenergetic-isochoric flash

Cited by 41 publications

References 4 publications

Dynamic simulation of flash drums using rigorous physical property calculations

Dynamic simulation of flash drums using rigorous physical property calculations

Differential-Algebraic Approach to Dynamic Simulations of Flash Drums with Rigorous Evaluation of Physical Properties

Dynamic simulation of fluids in vessels via entropy maximization

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