A compressor, an expander and an arbitrary separator model have been added to the BELSIM-COL70 steady state simulation package for multi-stage separation processes. The performance of the dogleg method applied to the global equation system of an extended version of Cavett’s problem is compared to the classical Wegstein method and the dogleg method applied to the torn variables only. The results of the simulation of a C3-splitter are compared to industrial measurements. Finally, the algorithm is applied to an azeotrope separation process with demixion in the liquid phase.