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Experiments are carried out to determine, under comparable conditions, the mass-transfer efficiency of a packed column in catalytic distillation of a chemically reactive mixture and in multicomponent distillation of the same mixture that is uncomplicated by chemical transformations. The reactive distillation process involves the reversible equimolar reaction of transesterification between butyl acetate and ethanol to form butanol and ethyl acetate. It is shown that the experimental data on the packed zone of the column are satisfactorily fitted by an equilibrium cascade model. The number of stages in the cascade is found from the Fenske-Underwood equation. In the experiments performed, both in the catalytic distillation and in the multicomponent distillation uncomplicated by chemical transformations, the height equivalent to a cascade stage is the same (20 cm).

Analysis of the distribution of components along the distillation column height is necessary in studying the column operation over a wide range of flow rates. The distribution of components depends significantly on the physicochemical nature of the mixture being separated, the hydrodynamic conditions of contact between the phases, and the heat-and mass-transfer rates [1][2][3][4]. An important parameter of the process is the liquid holdup in the column, which determines the residence times of the liquid and vapor phases at a contact stage. The liquid holdup is particularly important in analyzing the mass transfer accompanied by a chemical reaction [3,4].Let us consider the effect of the liquid holdup on the variation of the composition along the column height in distillation of binary and ternary ideal mixtures at infinite reflux ratio. Let us assume that the process is steady-state, the relative fugacity coefficients are constant, the liquid and vapor flow rates remain unchanged along the column height, the efficiency of each stage is unity, and the holdup of the vapor phase in the column is ignored. Figure 1 presents the flowchart of a distillation column. The vapor that leaves the upper part of the column and has concentration y n is completely condensed in the condenser and returns to the column at concentration x d ; consequently, BINARY SYSTEM(1)The material balance equation for the i th stage has the formwhence, with allowance for relation (1), it follows thatRelations similar to formulas (3) and (4) can also be written for other separation stages. The vapor leavingAbstract -The distribution of components along the distillation column height in distillation of binary and ternary mixtures is studied at different profiles of liquid holdup in the system. It is shown that physical modeling of continuous and batch distillation at infinite reflux ratio without taking into account the liquid holdup distribution may be inadequate to the real process. Equations for the curvilinear equilibrium line are proposed, which relate the number of transfer units, the number of theoretical separation stages, and the component concentration.

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The distribution of components along the distillation column height in distillation of binary and ternary mixtures is studied at different profiles of liquid holdup in the system. It is shown that physical modeling of continuous and batch distillation at infinite reflux ratio without taking into account the liquid holdup distribution may be inadequate to the real process. Equations for the curvilinear equilibrium line are proposed, which relate the number of transfer units, the number of theoretical separation stages, and the component concentration.