The first question is how sure are you that you have no foaming. Most field dehy units I have seen are relatively simple units with not much in terms of instrumentation on the towers. Assuming that you are seeing no obvious symptoms of foaming (fluctuating levels, reboiler temps, etc), the next question is how long has the plant been in service, and how long since the last turnaround where you have inspected the tower.
If it is an old plant, or you have not looked inside in a few years, it is possible that there is tray/packing damage that is messing with the hydraulics in the system. Internal damage can increase gas velocity through thr tower, causing the gas to "lift" the glycol out the top of the tower. A gamma scan is the best way to look for tray damage/foaming/channelling/ or any other phenomenon going on during plant operation. I suggest a gamma scan on both the contactor and regen.
Another possibility is a high hydrocarbon content in the inlet gas. C4/C5+ liquids (and BTEX) will be picked up by the TEG and introduced to the regen loop. If there is no flash tank especially, the TEG losses through the regen are potentially very high. The HC's will flash off in the high temp regen, resulting in a very high vapour rate out of the regen, again, lifting TEG out the top.
This is all I can provide with what I know of your system. Other questions I would have are:
- Are the losses continuous or do they occur at certain times (corresponding to ambient temps, inlet conditions, etc.)
- What are the operating conditions of the plant (T's & P's, circ rate etc)
- Filtation on the plant? Carbon? Lean or rich filtration?
