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  1. PaoloPemi

    How to add murphree efficiency to Column Inside-Outside method?

    you may consider this old thread https://www.eng-tips.com/threads/russell-inside-out-for-dist-column.156981/ it's about the version proposed by Richard (Dick) Russell which (as far as I know) has been the standard procedure in most simulators and thermo libraries, there are different ways to...
  2. PaoloPemi

    How to calculate isentropic tempera

    if you solve with Lee Kesler method results will be quite close to those reported in the book, I agree with Pierreick and gergeverghese, your compressibility factors / densities are wrong, I attach the solution calculated in Excel with Prode Properties (see prode.com) for your review...
  3. PaoloPemi

    Water properties Aspen Plus are off

    probably it depends from selected thermodynamic package for enthalpy calc's... for accurate results you should select ASME or IAPWS (95, the most accurate, or 97) these models however work only with pure fluids (not mixtures), not sure about the models Aspen includes, with Prode Properties I...
  4. PaoloPemi

    Bubble Point, RVP & TVP of Hydrocarbon Condensate

    MIANCH, is that a copy and paste from Aspen documentation ? Yes, you can estimate Rvp with many different EOS models (at least that is possible with Prode Properties, I would presume with Aspen, too). Yes, you can correlate ASTM D6377 with ASTM D323 etc. , there are graphs and correlations for...
  5. PaoloPemi

    Bubble Point, RVP & TVP of Hydrocarbon Condensate

    according API TDB the Reid vapor pressure (Rvp) is the absolute pressure exerted by a mixture (in psi) determided at 100 F and at a feed vapor to liquid volume ratio of 4 (see ASTM D 323 for details about apparatus and procedures, that is important to understand what Rvp means...), a software...
  6. PaoloPemi

    Sour water stripper unit

    >>Any books on sour water stripping process chemistry and unit operation are available..please share them many books available but you may start from original paper : "A New Correlationof NH3, CO2, and H2S Volatility Data from Aqueous Sour Water Systems" which includes a discussion on the...
  7. PaoloPemi

    Anhydrous Ammonia Boil-off Flash Calculations for Ammonia Rundown to Storage Tank

    for a binary you may be able to fit (with a VLE data-regression procedure) experimental VLE data in some (maybe limited) range but standard Peng Robinson may show several limits... a more suitable approach could be, for example, a EOS with complex rules (i.e. Peng Robinson + NRTL with Huron...
  8. PaoloPemi

    PSV Sizing, 2-phase flow prediction/test

    probably your manufacturer can propose the right tool (the reason being that there are many specific factors as valve's internals etc. which can affect results in complex models as for example non-homogeneous, non-equilibrium models) said that, there are many tools available and, since you...
  9. PaoloPemi

    Calibrating Peng-Robinson's EOS

    in standard Peng Robinson EOS, BIPs (Binary Interaction Parameters) are included in van der Waals mixing rules as fixed values calculated by data regression of Vapor-Liquid experimental data values (see Dechema), if you wish to fit VLE data (fugacity calculated by EOS) any data regeression...
  10. PaoloPemi

    Thermodynamic estimation of phases

    for phase equilibria one can solve fg(1)*x(1)=fg(2)*x(2)=... where fg and x are the component's fugacities and fractions in the different phases (vapor, liquid, solid...) it shouldn't be too difficult for vapor-liquid assuming for example ideal state laws (i.e. vapor pressure for liquids and...
  11. PaoloPemi

    Natural Gas Specific Heat Data Tables

    Pulsater555, for models based on ideal gas laws the generic correlations of H vs. T (from which you can extract (dH/dT)P or cp) are ok, for real fluids you should include departures (from ideal fluids) calculated with EOS or equivalent systems, see the previous threads at Eng-tips forums.
  12. PaoloPemi

    PSV Outlet Line Pressure Drop for Two Phase Flow

    the method in API 5.5.10 is based on the (simplified) omega formulation, these formulations dates back to 1980 when not many computer codes were available (see attached paper) In recent editions API suggests a procedure based on numerical integration for nozzles (see my previous post with the...
  13. PaoloPemi

    PSV Outlet Line Pressure Drop for Two Phase Flow

    as far as I know API formulation adopts an approximate analytical approach based on isenthalpic approximation and omega one parameter equation (see Leung papers for details), as alternative you can adopt numerical integration (solving many small steps) with the formulations in my previous post...
  14. PaoloPemi

    PSV Outlet Line Pressure Drop for Two Phase Flow

    if I remember correctly they proposed different versions, the oldest being quite simple. The homogeneous model treats the two-phase mixture as a single fluid at phase equilibrium (no slip). The (homogeneous) volume is defined as vm = X*vg + (1-X)*vl where X is the weight-flow...
  15. PaoloPemi

    PSV Outlet Line Pressure Drop for Two Phase Flow

    for additional details about the correlation proposed in API 5.5.10 you may refer to the paper "The Discharge of Two-phase Flashing Flow in a Horizontal Duct" by Leung and Grolmes as alternative you may consider the method based on HEM approach discussed in Emergency Relief System Design Using...
  16. PaoloPemi

    Steam PSV Inlet / Outlet Pressure Drop Calculation Methodology

    with sub-cooled liquids HEM model could give conservative results (compared for example with HNE-DS which includes a boiling delay), depending from operating point, anyway you should be able to solve with the help of steam tables. Another possibility, as said, could be to use a thermodynamic...
  17. PaoloPemi

    Steam PSV Inlet / Outlet Pressure Drop Calculation Methodology

    which is the purpose of your work ? If you wish to learn how it works probably the numerical examples included in standards / books / etc. could help, differently, if you wish to code a procedure a thermodynamic library (see my previous post) or a process simulator could help by solving the...
  18. PaoloPemi

    Steam PSV Inlet / Outlet Pressure Drop Calculation Methodology

    The Omega method proposed by Leung adopted a single point (pressure vs volume) to determine a compressibility coefficient ω "found to be a unique function of the stagnation pressure for a given fluid", note that first part of process is isentropic, second part is isenthalpic and one can...
  19. PaoloPemi

    Lee Kesler Plocker on Hysys

    in principle many thermodynamic models including cubic EOS (Soave, Peng-Robinson ...), corresponding states (Lee-Kesler...) etc. can predict multiple liquid phases... but it could also depend from some numerical instability in the solver (Lee-Kesler has multiple roots) and so on... I am not...
  20. PaoloPemi

    Mass flow quality 2-phase calculation in ISO 4126-10 (2010) - Low amount of vapour rate through psv

    they define x0 as the mass flow quality, i.e. the ratio of the gas mass flow rate to the total mass flow rate of a two-phase mixture, if you know total volume (of vessel, see also the definition of V) and (vapor and liquid) volumes you should be able to get x0 value, the paper presents a...

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