Excel library for process calc's including distillation

[asanter]

There is a method in Prode Properties for pipelines simulation,

Simulation of single phase, two-phases, multiphase flow on circular pipes (* available in extended versions)
int res = PIPE(int stream, int model, double diam, double rough, double length, double dHeight,
double dHeat)
models
Beggs & Brill / Hazen-Williams / AGA

I wish to simulate a transport pipeline (multiphase, hydrocarbons + water) , model Beggs and Brill,
does Prode Properties calculate heat balance if I specify the a dh (air/soil heat exchange) ?

[carlo.stenali]

asanter,
method PIPE in Prode Properties allows to specify the heat exchanged with soil / air / water ,
Prode Properties then calculates final temperature, pressure and phase equilibria,
you can specify the heat exchanged on each segment of the pipeline,
for long pipelines you may have different external conditions ( soil / water / air ) in different segments,
before to simulate a pipeline you need to evaluate the influence of surronding materials say dry earth, sand and/or gravel etc. this
may require some time but it's important for the accuracy of results.
In some cases (change of phase, high viscosity liquids) the influence is greater than in standard gas pipeline.

[asanter]

Carlo,
thank you for the answer,
I am simulating a 10 kilometers pipeline (natural gas + condensate),
we expect a different amount of condensation depending from external conditions,
which is the unit in the method PIPE for the heat exchanged with soil ?

[carlo.stenali]

with Prode Properties, method PIPE, when simulating a segment of a pipeline you can specify the amount of heat exchanged with surrounding environment using the same units of flash operations (H-P)
As you know in Prode Properties all the units of measurement are easily customizable so you can define standard US, SI or different units.

[mpat]

Hydrate software
I calculated hydrate formation curve in Excel with the rigorous model included in Prode Properties,
comparing hydrate formation conditions in presence of different amounts of methanol as inhibitor with experimental data from Sloan's
book I observe low errors for methanol weigh fractions below 20-30%,
Hammerschmidt's equation (utilized to predict influence of inhibitor) gives equivalent or higher errors,
my question : which is considered (engineer's best practice) the maximum amount of methanol to add into a natural gas stream ?
My client says they utilize up to 30% (weigh fraction) , is that figure generally accepted?

[asanter]

there are economical reasons which may put a limit,
we have evaluated Methanol, MEG, and NaCl ,
to get a depression of about 10 C in hydrate formation temperature about 32% (weight) of MEG is required,
with 30% (weight) of methanol loss in gas phase is about 500 kg / MSm3 , much lower with MEG

[abarre]

I use Prode Properties for calculating the phase envelope
of natural gas mixtures including some water, CO2 and H2S,
I would appreciate comments from experts about the package to utilize,
Prode Properties includes many variants of SRK, PR plus CPA, ISO 18453 etc.
the resulting phase envelope could differ sensibly depending on the model and the options.

[carlo.stenali]

for phase equilibria in mixtures of hydrocarbons+water+carbon dioxide+hydrogen sulphide
I would select a EOS with complex mixing rules (Wong Sandler or Huron Vidal in Prode Properties)
you may try CPA too.

[abarre]

thanks Carlo,
at last I decided to select Peng Robinson with Wong-Sandler mixing rules for phase equilibria,
depending from model selected for activity coefficient model (there are three variants in Prode Properties, PR-Wilson, PR-NRTL, PR-UNIQUAC) there are three or four parameters which may require some work when not available.
However it seems to fit well some experimental data which I have.

[carlo.stenali]

abarre,
according several papers Peng Robinson with Wong Sandler mixing rules can give good results for hydrocarbons + water,
possibly you need to tune parameters,
Prode Properties includes the data regression utility for that.

mpat,
I think asanter has just replied to your question,
different companies can adopt different practices but at last you have to calculate and compare the costs and benefits of different solutions

[stawad]

Co2 freezing point with Prode Properties
I am calculating Co2 (in natural gas) freezing point with Prode Properties,
according your experience which is the correct option as thermo package ?
Peng Robinson and Soave Redlich Kwong packages give quite equivalent results.
Thank you.

[carlo.stenali]

with multiphase vapor-solid equilibria in Prode Properties I have tested methane-Co2 and some other mixtures with Soave Redlich Kwong and Simplified Solid Model available in Prode Properties,
errors for freezing point temperatures are in a range from 1 to 5 C compared with experimental data,
I have not verified Peng Robinson but I presume it gives equivalent accuracy (I may be wrong)