Size a turboexpander-fed cryogenic demethanizer separating methane (residue gas overhead) from ethane and heavier (NGL bottoms). Uses Fenske-Underwood-Gilliland (binary C1/C2 key, C3+ all to bottoms) per GPSA §16. Distinct from Rich Oil Demethanizer — that calc models the lean-oil refluxed-absorber alternative.
Feed
MMscfd
%
%
%
Recovery & Spec
%
mol %
Operating Conditions
psia
°F
°F
—
—
📚 Theory
Why turboexpanders, GSP vs RSV vs ISS, key relative-volatility selection, side-reboiler trade-off.