Excel library for process calc's including distillation

[carlo.stenali]

yes,
the comments are interesting and I fully agree,
specifically for that mentioning some "unusual" phase diagram generated by extended EOS versions,
I have had a similar experience but the reason was some strange values for BIPs (I presume extended EOS should use a specific set of BIPs)

[mderra]

I have compared gas and liquid densities calculated by PRODE extended EOS with some values from NIST,
for several fluids as C3, C5, ammonia etc.
differences are usually within 2-4%

[carlo.stenali]

mderra,
my results confirm your observations,
the differences in liquid densities are (usually) lower than 3-5% outside critical area,
in critical area differences may be larger for mixtures,
take care to define correct BIPs (kij for EOS)
or set BIPs to 0 for mixtures such as hydrocarbons.

[cmarc]

may I add custom units in PRODE PROPERTIES ?
There is the description of the methods available in documentation but I would need an example.

[rense]

cmarc,
you can add custom units after std. units,
to add a custom unit use the method
UMAU(k1,k2,"unit",code)
where k1, k2 are the conversion constants (see the manual)
"unit" is the string to identify the unit as "M3/Kg" etc
code is the code for that unit

[carlo.stenali]

cmarc,
as suggested by rense you can add custom units in PRODE PROPERTIES,
for example to add Nm3/h (which is not included in gas flow units)
I do

k= mw * 0.00001239;
UMAU(k,0.0,"NM3/h",CONV_UM_WG)

where k is the conversion factor calculated from density at normal conditions

in the same way you can add units for SM3/h , SCF/h etc.

the main advantage with this method is that you can easily customize the interface with your own (standard and normal) units which may be different in different countries (in Europe normal and standard temperatures can change)

[Danny_Harris]

That's great software.......

[Almart]

mderra & carlo.stenali,
for liquid densities of polar fluids as water, ammonia etc.
the values predicted by Extended EOS are more accurate than Peneloux method,
however on derivatives of compressibilities (i.e. isothermal compressibility)
errors are quite large,
just to mention this.

[cmarc]

yes,
on derivatives of volume vs. pressure the errors are high for polar fluids,
however we do need usually absolute values (i.e. volumes, densities etc.)
not the derivatives,
for those a better model should be BWR or some related.

[abarre]

could you please explain how to add custom unit SM3/DAY unit for a gas flow?

[carlo.stenali]

abarre,
it's very easy to add new units to PRODE PROPERTIES,
you would utilize the method UMAU() to add new units,
see the description in the operating manual,

'http://www.prode.com/docs/pppman.pdf'

you need the define conversion factor, the name of the unit "SM3/Day" and the property (gas flow)

since you need a value at standard condition you can calculate the conversion factor from molar weight

UMAU(mw*1.175E-7,0,"SM3/Day",UM_WG)

where the first parameter mw*1.175E-7 defines the conversion factor
the second value is 0 as values start from 0
the third is the name for the unit
and the last is the property (gas flow),
see the operating manual for the numeric code of each property

[abarre]

thanks Carlo,
nice information,
for hours instead of days should I only change the constant?