Prode Properties

multi phase vapor liquid solid hydrate formation software

Do you need assistance or wish to discuss applications ?

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Interest for hydrates began when researchers found that natural gas hydrates can block gas transmission lines even at temperatures above the ice point, after the discovery many researchers starting from Hammerschmidt, Deaton, Frost investigated the effects of inhibitors such as salts (chloride salts...) liquids (methanol, ethanol, glycols as mono ethylene glycol MEG etc.) on hydrates, thermodynamic inhibitors lower the freezing point and thereby reduce risk of hydrate formation.

The necessary condition for hydrate formation is the presence of water (or ice), gas hydrates can form from dissolved gas or free gas. Thermodynamic inhibitors such as methanol, ethanol, mono ethylene glycol (MEG) etc. can reduce kinectics of nucleation, other inhibitors can reduce agglomeration of hydrate crystals.

Several methods are available to predict hydrate formation conditions, the old methods (Wilcox, Katz etc.) allow direct solutions while more recent methods based on Van der Waals and Platteeuw theory require a computer software.

The multi phase flash procedure in Prode Properties solves multi phase equilibria including solid and hydrate phases, given operating conditions and compositions the procedure calculates fugacities plus derivatives of each phase and the second order solver identifies the correct solution. A phase stability step removes unstable phases. The procedure doesn't require the presence of a free water phase and can include single or mixed salts (with electrolyte models).

Prode Properties includes two different models for hydrate phase, a simplified method and a complex method, both based on Van der Waals and Platteeuw theory. Prode Properties allows to select differnt models for vapor, liquid and solid fugacities.

Here, errors (for about 100 points) are determined as difference in hydrate formation pressure calculated by Prode Properties with CPA-PR model vs. measured data sets.

You can contact Prode to receive the complete data set with calculated data and the reference in literature.

- Simplified method, SI, SII, SH structures, mixtures with 2 or more formers, errors on predicted hydrate formation pressure :
- SI max error < 10% average error 4%
- SII max error < 20% average error 6%
- SH max error < 10% average error 4%

- Complex method, SI, SII, SH structures, mixtures with 2 or more formers, errors on predicted hydrate formation pressure :
- SI max error < 7% average error 3%
- SII max error < 12% average error 4%
- SH max error < 6% average error 3%

This Excel application example shows how to use Prode Properties to solve the multiphase flash operation including hydrates and get the results directly in Excel pages.

Open Prode Properties Editor and in Stream->Operating dialog select the stream 6 in both lists of first and second window

Prode Properties Editor allows to solve a series of predefined operations, select TP-VLSH as flash operation, then enter 277 K and 15 Bar.a as specifications and click on the button "Compute", the procedure will show the the formation of a hydrate phase

You can evaluate how the addition of a small amount of methanol (inhibitor) can increase the formation pressure for hydrate phase, we recalculate phase equilibria with a 0.002 mole fraction of methahol, as result we must increase the operating pressure to detect a hydrate phase, hydrate formation pressure is now about 70 Bar.

To improve the accuracy of phase equilibria in presence of inhibitors it is recommended to adopt specific BIPs calculated from SLE data points (you may contact Prode for assistance)

You can obtain the results directly in Excel (open the example page multiphase.xls included in distribution)

- Open Properties Editor Operating page and select stream 6
- in Models page make sure that multiphase vapor-liquid-solid-hydrate option is set, back in Operating page click on Save button and click Ok to leave the Properties Editor
- in Excel input the specified temperature, pressure and stream (6) and click on compute isotheraml flash to see the results

With Prode Properties you can calculate the hydrate formation temperature curve or the hydrate formation pressure curve and print a graph in Excel.

- open the example page hydrate.xls included in distribution
- select the stream 6, edit the stream to modify the composition, if required
- click on Calculate Hydrate Formation Curve button to generate the graph

Technical features overview (Windows version)

- Entirely written in C++ (since first edition, 1993)
- Up to 100 different streams with up to 50 components per stream (user can redefine)
- Several compilations of chemical data and BIPs are available, the user can add new components and BIPs
- Proprietary compilation with data for more than 1600 chemicals and 30000 BIPs
- flexible database format (support for up to 30 different correlations) works with all majour standards including DIPPR.

- Comprehensive set of thermodynamic models, base version includes
- Regular
- Wilson
- NRTL
- UNIQUAC
- UNIFAC
- Soave-Redlich-Kwong (standard and extended version with parameters calculated for best fitting of vapor pressure, density and enthalpy)
- Peng-Robinson (standard and extended version with parameters calculated for best fitting of vapor pressure, density and enthalpy)
- Benedict Webb Rubin (Starling) BWRS
- Steam Tables IAPWS 95
- ISO 18453 (GERG 2004)
- ISO 20765 (AGA 8 model)
- Lee-Kesler (Plocker) LKP
- CPA Cubic Plus Association (SRK and PR variants)
- Hydrates (Cubic Plus Association, Van Der Waals-Platteeuw)
- additional models as Pitzer, NRTL for electrolyte solutions, PC SAFT (with association), GERG (2008) etc.

- van der Waals and complex mixing rules to combine equations of state with activity models
- Huron Vidal
- Wong Sandler ( WS )
- Michelsen ( MHV2 )
- Tassios et al. ( LCVM )

- Base and Extended EOS versions with parameters calculated to fit experimental data from DIPPR and DDB
- Selectable units of measurement
- Procedure for solving fluid flow including multi phase equilibria and heat transfer
- Procedure for solving staged columns
- Rigorous solution of distillation columns, fractionations, absorbers, strippers...

- Procedure for calculating hydrate formation temperature and hydrate formation pressure
- hydrate phase equilibria based on different Van Der Waals-Platteeuw models

- Procedure for solving polytropic compression with phase equilibria
- Huntington method for gas phase
- Proprietary method for solving a polytropic process with phase equilibria

- Procedure for solving isentropic nozzle (safety, relief valve with single and two phase flow)
- HEM, Homogeneous Equilibrium
- HNE-DS, Homogeneous Non-equilibrium
- NHNE, Non-homogeneous Non-equilibrium

- Procedure for simulating fluid flow in piping (pipelines) with heat transfer
- Beggs and Brill and proprietary methods for single phase and multiphase fluid flow with heat transfer

- Procedure for fitting BIP to measured VLE / LLE / SLE data points (data regression)
- Procedure for fitting BIP to VLE values calculated with UNIFAC
- Functions for simulating operating blocks (mixer, gas separator, liquid separator) **
- Functions for accessing component data in database (the user can define mixing rules)
- gas / vapor-liquid-solid fugacity plus derivatives vs. temperature pressure composition
- gas / vapor-liquid-solid enthalpy plus derivatives vs. temperature pressure composition
- gas / vapor-liquid-solid entropy plus derivatives vs. temperature pressure composition
- gas / vapor-liquid-solid molar volume plus derivatives vs. temperature pressure composition
- Flash at Bubble and Dew point specifications and P (or T)
- Flash at given temperature (T) and pressure (P) multiphase vapor-liquid-solid, isothermal flash
- Flash at given phase fraction and P (or T), solves up to 5 different points
- Flash at given enthalpy (H) and P multiphase vapor-liquid-solid, includes adiabatic flash
- Flash at given enthalpy (H) and T multiphase vapor-liquid-solid, includes adiabatic flash
- Flash at given entropy (S) and P multiphase vapor-liquid-solid, includes isentropic flash
- Flash at given entropy (S) and T multiphase vapor-liquid-solid, includes isentropic flash
- Flash at given volume (V) and P multiphase vapor-liquid-solid, includes isochoric flash
- Flash at given volume (V) and T multiphase vapor-liquid-solid, includes isochoric flash
- Flash at given volume (V) and enthalpy (H) multiphase vapor-liquid-solid
- Flash at given volume (V) and entropy (S) multiphase vapor-liquid-solid
- Flash at given enthalpy (H) and entropy (S) multiphase vapor-liquid-solid
- Rigorous (True) critical point plus Cricondentherm and Cricondenbar
- Complete set of properties for different states
- gas density
- vapor density
- liquid density
- solid density
- gas Isobaric specific heat (Cp)
- vapor Isobaric specific heat (Cp)
- liquid Isobaric specific heat (Cp)
- gas Isochoric specific heat (Cv)
- vapor Isochoric specific heat (Cv)
- liquid Isochoric specific heat (Cv)
- gas cp/cv
- liquid cp/cv
- Gas heating value
- Gas Wobbe index
- Gas Specific gravity
- gas Joule Thomson coefficients
- vapor Joule Thomson coefficients
- liquid Joule Thomson coefficients
- gas Isothermal compressibility
- vapor Isothermal compressibility
- liquid Isothermal compressibility
- gas Volumetric expansivity
- vapor Volumetric expansivity
- liquid Volumetric expansivity
- gas Speed of sound
- vapor Speed of sound
- liquid Speed of sound
- vapor + liquid (HEM) Speed of sound
- gas Viscosity
- vapor Viscosity
- liquid Viscosity
- gas Thermal conductivity
- vapor Thermal conductivity
- liquid Thermal conductivity
- gas compressibility factor
- vapor compressibility factor
- liquid Surface tension

Typical applications

- Fluid properties in Excel, Matlab, Mathcad and other Windows and UNIX (**) applications
- Thermodynamics, physical, thermophysical properties
- Process simulation
- Heat / Material Balance
- Process Control
- Process Optimization
- Equipments Design
- Separations
- Instruments Design
- Realtime applications
- petroleum refining, natural gas, hydrocarbon, chemical, petrochemical, pharmaceutical, air conditioning, energy, mechanical industry