The only operation you can use in this case, I think, is the component splitter. So you'll have to know how the components distribute between permeate and residue gas. The split fractions are accessible, e.g. via an adjust or spreadsheet operation, so you can make it a little more advanced if you like.
Cheers,
Joerd
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.