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[fra.telli]

Hi everybody.

TEG Column Design.
sorry for long description, but I want to be as accurate as possible...

Problem Data:
Water Saturated Gas: 3,5MSm3/d @ 16°C; 62 barg (1876 Am3/h; 61,9 kg/m3; visc: 0.0131 cP)
Inlet water flow: 38.5 kg/h
Outlet water requirement: <3.4 kg/h (Dew P: -17°C @ 69 barg; 6°C approach temp already considered);
water removal: 38.5-3/38.5 >= 92.2%; let say >93%
lean TEG concentration: 99.5% (required by User)

GPSA suggests: "15-40 liters TEG/kg H2O absorbed" (cap.20 pag.32)
-> max consumption is 40x36 = 1440 l/h of TEG
[fig 20-70 seems to confirm above data with N=1,5 -> 5 (max 6) real trays]

Back to fig. 20-68.
with 99.5%wt TEG and -17°C Dew Point -> max contact temp ~37°C
-> @ 35°C, 63 barg; TEG viscosity is 21,2cP (min viscosity value); surf tens. 42.5 dyn/cm

With above figures, TEG absoption column in HYSYS works (actual TEG flowrate: 260 kg/h).

Looking deeper in column design, KG-Tower ver 5.0 was used for further analysis:

Consideration 1
viscosity value seems to be high - respect to 5cP, indicated as "normal"

Consideration 2A - valve trays - colum diam: 1400mm
even considering VG-0 valve, weir load is very low: circa 2 m3/h.m

Consideration 2B - packings - column diam: 1200-1400mm
liquid load is circa 1 m3/h.m2, that seems really too low


Initially, I was intended to use a pumparound to solve this problem (big rich teg circulation + 1,4 m3/h lean teg inlet; 1,4 m3/h rich teg outlet at chimney tray or column bottom).
But this will change column P&ID, adding circulation pumps etc... and Client wont be happy.
Furthermore, thinking back to basic, universally known TEG PFD's, I've never notice such solution...

So, where I'm wrong?
(yes, I know I should contact KG or any other internals supplier, but before doing that, I'll like to "see" the simple element that I'm missing)

Thank you in advance for any hint/suggestion.

as far as I know, the TEG flowrate is really very low for the process, you could tray cap tray of structrue packing. we get new type tray which is mainly operating by spray, it is very nice tray for de-water from natrual gas.(anti-foaming mechanism)