Abstract A global Newton-Raphson method for the solution of multistaged multicomponent separators, in which one or some of the present components have a relative volatility very different (low or high) from all the others, is presented. The possibility of solving problems with many kinds of non standard specification equations has been taken into account. Distillation columns in which water is present (as for example stripper) are examined more in detail. In particular the ability of account for a possible aqueous liquid phase separation in the condenser is introduced in the numerical method. Finally two examples of application of practical import are reported.