i'm trying to design a distillation column which will separate propane from butane (at 18 atm) and i'm looking for the equilibrium curve for the mixture butane-propne... i didn't find it.
you have access to a process simulation software? i don't think there is a single one out there which is unable to calculate VLE. especially for a mixture of propane and butane (n-butane, i presume), which has no particularities whatsoever.
actually, aspen is not only capable of calculating binary VLE, it is - contrary to others - even able to calculate ternary VLE ("residual maps". none the less i have mailed you the needed data.