3 replies to this topic

[PYG]

Although the Hydrate formation temperatures and inhibitor flow rates can be predicted with simulation tools (such as HYSYS), GPSA Sec 20 provides methods to estimate flow rates of inhibitor with Hammerschmidt equation and Niels Bucklin equation. The attached spreadsheets present these calculations to predict hydrate inhibitor flow rate along with correlations for hydrate formation temperature and water content calculation for natural gas. These sheets are based on in-depth and extensive research done by Mr. Ankur Srivastava a few years back. 

 

Comments and feedback are welcome on the attached sheets. Any issues/errors identified in the working can be brought to my attention, and would be much appreciated.

 

The sheets can also be accessed at the following link:

https://www.linkedin...njection-gupta/

 

Attached Files

•  Hydrate Inhibitor Calculations_Hammerschmidt Eqn_rA.xlsm   809.14KB   173 downloads
•  Hydrate Inhibitor Calculations_Nielsen Bucklin Eqn_rA.xlsm   808.13KB   105 downloads

[PaoloPemi]

thanks !

If I may add a few comments, I would suggest also this page for a detailed discussion,
 
https://petrowiki.or...drate_formation

a problem with hydrates is that a hydrate flash program can be very complex and simplified estimates are not (in general) very accurate,

however there are many books (see for example Sloan Clathrate Hydrates of Naturale Gases) discussing the methods to predict hydrate formation conditions and including free tools based on the rigorous van der Waals-Platteeuw procedure)

there are also the free versions of Prode Properties which includes several rigorous multiphase hydrate models,

https://www.prode.com/en/hydrate.htm

finally, about thermodynamic inhibitors (methanol, ethanol etc.)  take care that with relatively large fractions (> 30-50%) predicted values can be subject to large errors even with complex methods, there are many threads discusing these topics at Cheresources...

[mahfuzrahman77]

Hello PYG,

 

Thanks for sharing the excel sheet. But apart from natrual gas, we usually use MeOH in our facilites to de-freeze out butane production lines. Any calculations on how much methanol is required for such liquid products having propane, butane and pentane?

[serra]

mahfuzrahman77,

 

are you interested to limit hydrate formation (in presence of hydrate formers + water) or solid formation ? in both cases methanol is a commonly used inhibitor...

I have tested several correlations as that proposed by Hammerschmidt to predict hydrate formation with inhibitors, the main advantage is simplicity but in general accuracy is limited...  the same about the correlations to predict the freezing point of a mixture...

A better approach is to solve the multiphase equilbria including solids / hydrates, there are Excel libraries (Excel addins or plugins) as that previously mentioned (Prode Properties) which you may test.