Hi,
I never heard of such an algorithim, but wish I had. Usually equilibrium/composition problems are not too hard to solve on your own (if they are fairly small), unless you need this particular program. One usually has a couple of mass balance constraints and some equilibrium quotients. You just use the logs of the equilibrium equations and you have N non-linear equations and N unknowns. Newton-Raphson or one of its variations (e.g. Powell's method) usually work because you can compute an analytical Jacobian matrix. Of course I may not be understanding your problem correctly and aswering a question that you never asked.
Regards,
Keith
