In this paper, it is shown that despite the large number of states and equations describing a distillation column the dynamics can be analyzed by lumping the states into a few variables characterizing the total holdup, Changes in holdup are compared to the global mass balance to derive a vector field describing the trajectories of the product compositions. The vector field contains detailed information about the dynamic behavior and is obtained without performing a complete dynamic simulation. Here, the procedure is applied to homogeneous azeotropic distillation, but with appropriate adjustments, it should be applicable to any column.