5 replies to this topic

[ALEXV]

I am simulating a gas dehydration plant for an upstream project and i have seen significant hydrocarbon liquid drop out in my simulation and changing the type of hexane plus, from N-hepatane to Other hexane plus species has significant impact on out come results.

 

Does any one compared the hysys results with the actual flow rates in the field at gas dehydration plants?

[serra]

when simulating a phase equilibria you must make sure to define the correct composition in order to obtain accurate results,

if you need to characterize C6+ fraction take case to use a proper procedure,

the other important parameter being the thermodynamic model selected for gas and liquid fugacities,

with hydrocarbons + water + TEG (or similar) I usually prefer the CPA model (which is available in my copy of Prode Properties) ,

also in this case take care that some reports available on web showing good results with Peng Robinson may not be extended to your specific application.

[ALEXV]

Serra,

thanks for the comments. i am not familiar with CPA model, would you mind to give me more details about it?

Regarding the C6+ plus: Gas Processing by Campbell-Vol3- section 5 has a good property predicting method for this component.

I will try to upload a summary of that in this forum.

I am not dealing with TEG system in my project, i only have simple cooling by aircooler and condensation. C6+ has significant affect on the condensate rate in LKO pots.

Softwares such as Promax, have special package for TEG dehydration because TEG dehydration is very popular in industry.

[ALEXV]

 GPA 2261 suggest to split the C6+ fraction into several components, typically 50% n-Hexane, 25% n-Heptane, 25% n-Octane, in some cases this recipe may give reasonably correct results in others (when heavy components as C9, C10 etc. are present) the agreement with measured dew points can be poor.

[PaoloPemi]

Alexv,

you may find information about Cubic Plus Association (cpa) with Google,

about C6+ charaterization there are different procedures available,

GPSA gives several recipes,

but it is difficult to estimate the accuracy of such procedures,

if you have additiona information (for example points on dew line)

you can define a composition with some data fitting procedure.

Edited by PaoloPemi, 04 July 2013 - 09:35 AM.

[ALEXV]

I have done a lot of trial and errors on the model to determine the best C6+ composition. finally I could match the field data with model data but not with GPA method. I broke up C6+ to C6, C7, C8, C9 and C10 and assumed C10+ is negligible. I got reasonable results.

 

Cheers