Condensate Vessel Pressure Drop

[B62plant]

I have gas at 1500 psig dropping to 850 psig across a JT valve.
The resultant condensate from the letdown flows into a 2 phase separator through a Schoepentoeter baffle with liquid flowing out to further processing and gas coming out through a demister.
I am seeing at certain times a DP across the separator of 40 psi (usually DP <2 psi) and I cannot understand why as no other process conditions change.
I thought at first it was hydrate formation but I ran HYSIS simulation and crystal formation is not possible at these conditions (water content <0.2 lbs/mmscf).
I am at a loss as to why I experience this DP and it does not cause me any problems, no other process changes.
Only thing I notice is it happens at high ambient temperatures in afternoon (I am in Middle East so quite hot).
Instrumentation is fine, it's a genuine DP.

Anyone ever experienced this ?

 

[georgeverghese]

Gas- lean TEG exchangers would work okay (in principle) if TEG flow is kept in sync with gas flow. When TEG rate is fixed, as in most gas plants, lean TEG would be too hot getting into the contactor when gas flow is lower than design. Modern designs use an independant air cooled HX for lean TEG feed to contactors for this reason - something to consider for facilities improvement.
Gas - TEG cross HX would work only if the HX is sized to enable sufficent cooling even when gas flow is down to min turndown - this requires a larger HX, and most EPC TEG unit suppliers wouldnt design for this case unless specifically called out for (or implied) in the plant Owners design contract. Additional process controls would also be required in this case to prevent overcooling the lean TEG at gas flows higher than min turndown.