Excel library for process calc's including distillation

[carlo.stenali]

dbert,
I am not sure that a theory explaining the phenomena has been universally accepted,
I have read that for small void fractions there is bubbly flow,
in that regime (with a uniform distribution of spherical bubbles) acoustic and kinematic perturbations are absorbed by bubbles,
may be there are other theories to explain the reduced speed of sound under these conditions.

[dbert]

thanks Carlo,
indeed I have read several papers discussing this phenomena and any author seems to support a different theory :-))
also I have found only a few experimantal measurements for the speed of sound in two phase flow

[carlo.stenali]

I would suggest the paper "Sound Speed in Liquid-Gas Mixtures : Water-Air and Water-Steam" author Susan Werner Kieffer,
among the different mixtures considered there is water-air, where the addition of small volume fractions of air causes a dramatic lowering of the speed of sound by nearly three orders of magnitude...

[asanter]

I wish to calculate a vapor-liquid-liquid phase envelope,
there is a mixture originating two liquid phases in certain conditions which I wish to investigate,
can I calculate a three phase envelope with Prode Properties?
I see in the operating manual that both three phase and multi phase envelope are included (in extended versions)

[matrenel]

asanter,
with Prode Properties you can calculate
-Vapor-Liquid phase envelope
-Vapor-Liquid-Liquid phase envelope
-Vapor-Liquid-Solid phase envelope
these are not available in base versions, you should contact Prode to obtain the extension.
I utilize the Vapor-Liquid-Liquid phase envelope for Hydrocarbons+Water, in this case water forms a separate phase and we get three different lines, a dew point line (water) and vapor-liquid-liquid
Hoping this helps.

[carlo.stenali]

asanter,
as matrenel said with Prode Properties you can draw
vapor-liquid; vapor-liquid-liquid, and vapor-liquid-solid T-P phase diagrams (phase envelope),
by the way if you work with Excel you can easily include additional properties as enthalpy , entropy etc. with some VBA code,
Prode Properties allows direct access to a large number of properties which you can include in graph

[asanter]

thanks matrenel and carlo.stenali,
I have been in contact with Prode to get the extension and I can now draw a vapor-liquid-liquid phase envelope in Excel,
as commented by matrenel I need this feature for mixtures with Hydrocarbons+Water,
the standard vapor-liquid phase envelope doesn't work well with high amounts of water (not a frequent condition but...)

[rense]

I am calculating vapor-solid equilibria with Prode Properties,
we have a hydrocarbon's mixture with about 6.4% CO2,
which is in your opinion the best model to select for gas (and solid) fugacity,
Soave Redlich Kwong, Peng Robinson or...

[rense]

I am calculating vapor-solid equilibria with Prode Properties,
we have a hydrocarbon's mixture with about 6.4% CO2,
which is in your opinion the best model to select for gas (and solid) fugacity,
Soave Redlich Kwong, Peng Robinson or...

[carlo.stenali]

you should get quite equivalent results with both Soave-Redlich-Kwong and Peng-Robinson equations of state.
There have been many discussions about which is the best model,
I think it depends from the field of application,
some authors give criteria for selection,
for example for hydrocarbons with acentric factors < 0.3 Soave Redlich Kwong is suggested,
however this is true for standard alpha correlation,
with the extended version available in Prode Properties (with parameters regressed to fit vapor pressure, enthalpy and liquid density of pure components) you should get quite equivalent results.

[rense]

carlo.stenali,
is the criteria based on acentric factor (when < 0.3 Soave Redlich Kwong is suggested) related to the average value of acentric factor of the mixture ?

[carlo.stenali]

rense,
this criteria allows to decide which model to apply for (gas or liquid) fugacity,
it is based on comparative analysis of original alpha correlations which are

0.48+1.574*w-0.176*w*w (Soave)
0.37464+1.54226*w-0.26992*w*w (Peng Robinson)

these values have been regressed from different data sets