5 replies to this topic

[mosayef]

Hi all,

 

I want to ask about column type in TEG contactor. I usually find it in tray column type, but when I contact the vendor, they propose packing column as the new technology in TEG Dehdyration Unit.  I want to understand what the the differences between this two. Could you please give me a reference/book/etc so I can understand ?

Is there any standard or code to estimate the size of Packing TEG contactor ? if tray column is used, I can estimated the contactor size by using GPSA chapter 20. Please give me info to size packing column of TEG.

 

Thanks J

[Bobby Strain]

You will want to use structured packing. The vendor will size it for you. Or you can find a supplier who will build it all in a module.

 

Bobby

[Mathi]

Shell DEP 20.04.10.10-Gen. can be used to size the glycol dehydration column. Also, try API SPEC 12 GDU.

 

mathi

[gegio1960]

in my experience...

either tray or packing is your (ie the process designer) choice.

packing is preferred because of the lower costs of the whole system (tower+internals)

trays are chosen in case of dirty systems or when a future capacity increase has to be considered.

good luck!

[Pronab]

Structured Packing column is preferred as there is  fixed TEG flow.

Edited by pronab, 27 August 2015 - 09:33 AM.

[Art Montemayor]

Mosayef:

 

What Bobby Strain and Pronab have recommended is, in my opinion, the best engineering advice you can receive on your query.  If you are trying to estimate your required TEG contactor’s (or absorber) size you are much better off if you follow what Bobby states.  A structured packing supplier is in a position to decide on what type of structured packing and its dimensions in an experienced and authoritative way - something that textbooks, magazine articles, or even consultants cannot do.  It is much wiser to follow the advice of those who have developed the technology and control the design performance of such engineering tools and equipment.

 

The reasons for employing structured packing instead of trays in a TEG absorber are many:

• As Pronab states, your basic design is normally designed for a fixed capacity (and therefore a fixed TEG flow rate) and turndown capacities and controls are not normally required.  A packed column follows this criteria.
• Structured packing yields a lower, desired pressure drop.  When used in the Stripping column, its low pressure drop is a net advantage because it keeps the reboiler pressure and temperature as low as possible - which is what you want to do to avoid TEG degeneration.
• Structured packing is normally designed (as most TEG absorbers) to serve out its working life without any maintenance or access required.  This follows in the same concept as making the TEG contactor as hermetic as possible (a minimum of nozzles and no manways (whenever possible).  This also follows with the requirement of feeding only clean and uncontaminated feed gas to the contactor.  Trays require internal access for scheduled maintenance.  In a natural gas dehydration plant you want to avoid - or minimize - maintenance wherever possible - especially human entry into vessels.
• Depending on the type and supplier, structured packing may not be cheaper than trays.  However, it’s advantages counter this.