problem with ethylene glycol injection for hydrate inhibition

[bham49]

We have a natural gas refrigeration plant that should operate at -20F so we inject 80% ethylene glycol for hydrate inhibition. When the EG is present the plant will warm to about 5F and the EG seems to dam up in the system. If we inject MeOH instead of EG the plant will operate at -20F. Once the EG is reintroduced the plant warms again even if we continue the MeOH injection.
Is there a corrosion inhibitor, well treating chemical, etc. that could be entering the plant and reacting with the EG to coat the chiller tubes and inhibit heat exchange?

 

[maddocks]

Are you sure you're using 80 wt% EG? Sounds like it's DEG or even TEG and this super high viscosity lowered temperatures is causing the fluid to gel. Send in a sample. Your 80wt% should boil at 255 Deg F. Your symptoms are unusual.

 

[bham49]

We have sent samples of the glycol to the lab twice thinking we may have some DEG, TEG, or an amine and both samples came back as over 99.6% EG. Our regen temperature and hydrometer readings show that we are right around 80 wt%EG. We are confident the EG is OK, but the plant will only get cold when the EG injection is turned off.

 

[maddocks]

Are you losing any EG when it is running? Maybe you're injecting hot EG directly into the LTS? Try and turn off the coil that may be located in the LTS. Verify injection nozzles, spacing, spray angles, and rates. Something is very weird here. Do you have a glycol heat coil in the propane suction scrubber?

 

[bham49]

The EG is injected into the gas stream at about 100F upstream of the gas/gas and chiller. There are no coils in the LTS or suction scrubber.