A feasibility study on batch extractive distillation is based on analyzing profile maps. The existence and location of singular points and separatrices in these maps depend on process parameters. The limiting flows of the process are related to those parameter values where the map changes shape. Graphical tools can be used to roughly estimate these values. If a singularity is not found using graphical methods, one cannot guarantee that a singularity does not exist. Reliable computation of all zeroes of a nonlinear multidimensional function can be used to determine these points. This can be accomplished using interval arithmetic. An interval arithmetic-based branch-and-bound optimizer is applied to find the singular points and bifurcations. All the singular points of the maps at specified process parameters are found in this way. Limiting flows are determined with the same methodology by finding the bifurcation points and the corresponding parameter values. (c) 2006 American Institute of Chemical Engineers.