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[Ghasem.Bashiri]

Dear Friends


I should design a Mol. Sieve Dehydration Unit Upstream of NGL Recovery Unit.
Minimum operating Temperature in NGL Recovery Section is -118°C.
For Dehydration Unit -110°C water dew point ( in 10 Bara)has been specified in outlet ofthe unit.
IN GPSA 11th -100°C (without Reference Pressure) has been proposed for minimum water dew point possible for Molecular Sieve. But in 12th Edition this lower limit has been changed to -117°C.
My question is that:
Is it required to meet such very low dew pint (I know hydrate formation....) But for 24 kg/hr water in 400000 kg/hr natural gas mixture hydrate may be carry overed if case of formation in NGL plant.
"Dew" for water in -110° has no meaning because water in gas mixture in gas of condensation will form ice or hydrate immediately.

AMETEK provide 0.1 ppm as practical lower limit for water content measurement. we can guarantee something that we can measure it. Is it better to specify water content instead of water dew point?

HYSYS report water dew poin for my stream as -120°C. What is the proceduee of HYSYS for such calculation. When I set mole fraction of water in the stream HYSYS report -214°C as water dew point. based on this report I can not accept HYSYS calculation without any feed back.
Please provide me some backup document from Aspen HYSYS or other technical document if you have.
My email: Ghasem.Bashiri@gmail.com
Regards
A.Bashiri