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Problem With Helium Component In Amine Pkg


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#1 Padmakar Katre

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Posted 10 March 2008 - 10:04 AM

Dear All,
I am facing in one problem here in Hysys simulation regarding the component listing with fluid package. My problem is I have a feed stream of the natural gas which contains Helium and Mercury like components. Now I have to simulate the entire LNG train which include units like Amine sweetening, Dehydration and later I have a scrubbing unit where I have split of the feed which has two outlets one goes to the Liquefaction section mainly lighters which contains N2, He, C1 and some traces of the Heavies like C2 onwards and the bottom outlet which mainly contains heavies which goes to the Fractionation Unit. My main concern is the overhead stream from which I have to recover the Helium. In my simulation I am using the different sub-flowsheets for the different units with different fluid package like Amine Package for the Amine Sweetening Unit, Glycol Package for the Glycol Dehydration unit and for the rest I have 2 options like SRK and PR. As I want the entire train in one model in Hysys I am facing problem with the compatibility of the components with the Fluid package e.g. PR and SRK can’t accept the MEAmine but I get option of either to delete the component or to keep in simulation just by checking and un-checking the right box. But in case of the Amine Package I don’t have this option for keeping the components like Helium which is not compatible with the Amine package I get warning that Amine Fluid Pkg will delete the Helium component as it is not listed with the Amine Pkg (original Hyprotech Amine Pkg) as well with the D.B. Robinson Associates Amine Package (Amsim 7.0). Just to get the rid of this problem I tried to make helium as the Hypo component and I made the necessary correction in the Hypo Manager still I am finding much difference of the Critical properties So I am not able to get rid of this problem.
1. I want to justify your first doubt which may come into your mind is – Make the separate models for the each unit. Now my concern is I have the data which is for the Light Feed Case, Heavy Feed Case and the Actual Sampling of the Unit which deviates from the 2 cases. So I want to make a complete model of the train where I will make change in the feed conditions and see the effect of it on the Helium Recovery.
Any kinds of details you want please let me know. Thanks in advance for your help and assistance.

The wonderful thing here by the licensor is in case of the Amine sweetening Unit the Helium component is missing and after amine sweetening there is Helium. The more interesting thing I found is in this amine sweetening simulation (in Hysys) they treat helium as Nitrogen which I came to know from the material balance is it not credible to consider the helium as a component’s interaction with other components during the amine sweetening and dehydration units.

#2 joerd

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Posted 11 March 2008 - 08:41 AM

I doubt if you will see much difference in the amine / dehy units if you "pretend" that your helium is nitrogen. One thing you can do to work around the incompatibility is to use a component splitter upstream your amine unit, to split off the helium, and let it bypass the amine and dehy units. Mix it back into the treated gas after the glycol unit. Absorption of helium in MEA or glycol is nil for all practical purposes.

#3 Padmakar Katre

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Posted 11 March 2008 - 10:00 AM

Dear,
Thanks for reply. I did the same thing I put the component splitter and removed helium before going to the Amine sweetening unit which is in the Subflowsheet with the amine pkg and the main flowsheet with the PR. I just wanted to know the helium interaction with the Glycol and the MEA. As I was going through the reference documents like the research articles by the BRE but I didn't find anything related with the amine-helium interaction. Anyways thanks once again. And looking forward to get some referances related to the query.

#4 Zauberberg

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Posted 11 March 2008 - 10:17 AM

Padmakar,

Bypassing amine and dehydration unit is the best thing you can do. I don't know what is the content of helium in your gas stream, but it will not make any undesirable or unpredictable effects. Using component splitter and artifically removing helium is good idea, assuming that helium content is low; if it is substantial (more than, let's say, 5%) replacing He with N2 and feeding amine unit is the next best approach, simply for the reason not to disturb your gas stream relative concentrations.

I recall similar issues with certain hypos (I don't remember what was the case, though) and I simply removed them, without jeopardizing simulation results. You can do this, try to replace He with different inert compounds and you will see the effect is esentially - zero.

Best of luck,

#5 Srikrishna Chaitanya

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Posted 14 March 2008 - 04:23 AM

Dear Padmakar ,

i just want to share my experience with the amines package , recently i have done simulation for CO2 removal system , it contains basically a Absorption column and a MDEA regeneration stripper , my Natural gas also contains Argon in it , Similarly as in your case amines package deleted argon , i tried in different ways to put argon in it like you but I am not successful , finally i have done simulation replacing argon with nitrogen , i tried to match flow rates and compositions in the flow sheet , any way i got pretty good results with Amines package , little temperature variation is there that is plus or minus 5 degrees.


Regards,
Satish




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