Methanol in Ethane product

[Jack Nicholson]

Hi. I have a question. would you please help me?
In natural gas feed to demethanizer column, there is a trace amount of methanol (1 ppm). Also in order to remove ice blockage, trace amount of methanol (200 lit) in 15 min has been injected in feed line to demethanizer.
Here is the problem. On the top of deethanizer column (ethane product), there is trace of amount methanol! How could this happen? I thought that boiling point of methanol is higher than heaviest hydrocarbon, and it should goes with C5+ product.
P.S.: on the top of demethanizer we couldn't analyze methanol content.
Thanks in advance.

 

[georgeverghese]

Though ethane and MeOH do not form an azeotrope, MeOH and propane do (from citings on the internet) at approx 310degK. The MeOH may be therefore existing as an azeotrope with residual propane in C2 column overhead C2 vapor.