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Hydrogen Blanketing In Selective Hydro-Desulfurisation Unit


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#1 pallavikhatri

pallavikhatri

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Posted 01 March 2016 - 09:01 AM

Dear All

At present I am working on a Selective hydro desulfurisation unit using Axens technology. In the desulfurisation unit, the naphtha feed surge drum is blanketed with hydrogen. 

I just want to ask in what scenario hydrogen is used as a blanketing medium? In the hydrodesulfurisation unit why cannot we use nitrogen instead of hydrogen as a blanketing medium?

 

Thanks in advance.

Regards

Pallavi



#2 Bobby Strain

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Posted 01 March 2016 - 04:13 PM

There is nothing wrong with a hydrogen blanket. Nitrogen may contain some oxygen which is not good. And, you don't want to vent nitrogen into your fuel or flare system.

 

Bobby



#3 Profe

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Posted 03 March 2016 - 01:02 PM

Hi Pallavikhatri.

About your concerns with hydrogen. I agree Bobby´s advice. And also hydrogen in the hydrodesulfurization it is part of reactions.

For a better understanding, I copy the following paragraph from "Petroleum Refining - Technology and economics" 4th ed from J Gary, G Handwerk (marcel dekker, 2001). Chapter 9 Hydrotreating.

 

"Hydrotreating is a process to catalytically stabilize petroleum products and/ or remove objectionable elements from products or feedstocks by reacting them with hydrogen. Stabilization usually involves converting unsaturated hydrocarbons such as olefins and gum-forming unstable diolefins to paraffins. Objectionable elements removed by hydrotreating include sulfur, nitrogen, oxygen, halides, and trace metals. Hydrotreating is applied to a wide range of feedstocks, from naphtha to reduced crude. When the process is employed specifically for sulfur removal it is usually called hydrodesulfurization, or HDS. To meet environmental objectives it also may be necessary to hydrogenate aromatic rings to reduce aromatic content by converting aromatics to paraffins."

 

I Hope this little bit of knowledge will be useful.

 

Good luck

Fausto.


Edited by Profe, 03 March 2016 - 03:05 PM.


#4 shantanuk100

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Posted 19 March 2016 - 10:00 PM

Dear Pallavi,

 

1. Hydrogen is a part of the Hydrodesulfurization process. It is a basic reactant in it.

 

2. Nitrogen might contain associated substances which are likely to cause catalyst poisoning. It could be due to Oxygen or any similar substance.

 

3. In the HDS process, the outlet of the Gas separator and the Stripper units, is sent to an amine contactor for Sour to Sweet gas conversion. The exit from this unit is Hydrogen rich H2S free gas which is sent back as a recycle loop.

 

Due to these 3 reasons, you choose H2 as your gas blanket in place of N2

 

Regards,

Shantanu Kallakuri


Edited by shantanuk100, 19 March 2016 - 10:00 PM.


#5 Art Montemayor

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Posted 20 March 2016 - 09:38 PM

pallavikhatri:

 

Now that you have posted duplicate and identical posts of the same query in this Forum, which one of the posts do you want answered or responded to?   How many more duplications of this same topic are you going to post?

 

The reason I ask this is because you now have caused complete confusion with our members as to how to where they should respond to your multiple posts regarding the same topic.   In order to establish and maintain sensible and logical organization within our Forums and enable our member to respond without having to post multiple responses to the same topics, our Forums forbid what you have done.  I will have to delete all but one of your duplicate posts.  Tell me which thread to delete.   We cannot tolerate multiple postings of the same topic when one, simple, and logical thread will do.  Otherwise you will convert your threads into a crazy maze of responses or the inability of our members to decide which thread to respond to.  That is madness, and not logical engineering.

 

I await your quick, and specific response.  If you don't respond, I will delete whichever thread I come to first.

 

Thank you.






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