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[vista]

Well we are using TEG to remove moisture from the natural gas stream...I have a question related to regeneration section containing a reboiler and a still column mounted on a top of a reboiler containg Paul rings...the rich TEG from the flash tank enters the top of a still cloumn just above the Pual rings and from the bottom hot vapors from the reboiler enter the Paul rings section...this packing provide intimate contact between the rich TEG and hot vapors (the removed moisture) from the reboiler...

I want to know what is the basic purpose of these rings in the still coulmn?the still column also has a reflux coil above the packing which is used to control temperature and to minimize the TEG losses...


and onething more that what is effect of increased/decreased specific gravity of TEG?

[Art Montemayor]

Vista:

Pall rings are just one of many “packing” types employed within distillation and stripping columns in order to facilitate the intimate contact of ascending vapor and falling liquid and carry out a simultaneous heat and mass transfer.

These packing materials are fabricated such that they afford an extended surface area that allows itself to be coated by the falling liquid and exposing the same surface to ascending vapor. There are many type of configurations and styles of packing used in industry, made of various materials of construction – from ceramic, steel, stainless steel, to plastic.

The original packing material employed in the last century was the Raschig Ring – which was nothing more than a ceramic cylinder with its diameter equal to its height.

By allowing the “rich” TEG to fall through the still and coat the Pall Rings while hot, stripping gas ascends, the water content in the rich TEG is released and exits the top of the still column as a hot steam vapor, converting the TEG into “lean” TEG that falls into the reboiler and exits there to be cooled and return to the TEG contactor to absorb more water vapor from the natural gas being dried.

The TEG being circulated is essentially 100% pure TEG, undiluted with the exception of the quantity of water vapor the lean TEG picks up in the TEG contactor. Therefore, I don’t see how you can expect the specific gravity of the TEG to change in the process at any one specific site. Specific Gravity is defined as the ratio of the density of the substance (TEG) to the density of water at a stated temperature and pressure. The density of the TEG varies throughout the dehydration process due to its temperature, but this is not an effect that is normally controlling within the process. I don’t understand the nature, concern, or reason for your query.