Hello all,
I am process engineer working on producrion facality in Ukraine. We are running standart TEG dehydration unit, which design for gas flow 15 MMSCFD of day at pressure 30 bar and gas temperature +25 deg. C. We are using TEG to get water dew point -15 deg. C. After few month of running we get problems with water dew point, which is now is +2 deg. C and we found that 50 % of water from glycol sump tank is aromatic hydrocarbons like benzene, toluene, ethylbenzene, and xylene. Total flow from glycol sump tank is 300 lit/day. 50% is water and 50% is of liquid is hydrocarbons (aromatics) with SG 0.816-0.840. The lean TEG now is 83% by mass so regeneration system does not work properly. This confirms with high water dew point +2 deg. C.
Initial gas compositions shows only C6+ components, so we do not know about it content in gas upstream TEG contactor. I want to make full gas analys soon.
As I see now we have a two problems:
1. High water dew point of gas +2 deg. C - due to bad quality of lean TEG
2. Condensate (aromatics) flow from sump tank 150 lit/day - due to aromatics in rich TEG.
I run model in Hysys and saw that about 50% of aromatics going with rich TEG from TEG contactor to regeneration and then with water vapours going to sump tank. So my model shows the same as real dehydration unit. Ideally it should be water only and very small amount of HC.
Please if you have any ideas what we can do with this issue
Ideally carbon filter should remove aromatics and glycol flash tank should separate it from TEG. Note that TEG lean flow is 15 lit/min, carbon filter designed for 6 lit/min and glycol flash tank is two phase vessel only. There is only provision for HC outlet and two level gauges.
Regards,
Dmitry