The total-reflux operation of a batch distillation column has been reevaluated in terms of its simplicity: i. e, only the holdup of the reflux drum is required to be constant during the operation. However, when some disturbances occur during the operation, the desired products may not be obtained even if the holdup of the reflux drum is kept constant. In this paper, the disturbance suppression effect of middle vessels was examined by simulations. First, in order to quickly calculate the dynamic behavior of the system, a new mathematical model was proposed on the assumption that the column has an infinite number of stages. After the accuracy and the efficiency of the proposed model are confirmed, the model was used to evaluate the suppression effect of the middle vessels on the disturbances. As the disturbances, the set point error of the reflux drum holdup and the oscillation of the reflux flow rate caused by the inadequate control system are selected. The simulation results showed that the effects of these disturbances on the product compositions are effectively suppressed by the installation of a middle vessel. Furthermore, in most cases, the time required for the separation becomes shorter when a certain amount of holdup is assigned to the middle vessel.