Although considerable attention has been paid to the characteristics of the circulating fluid system, little information has been published as yet on the exact method to deal with the case in which the consumption of added chemicals takes place in one tank and the short-circuit by overflowing occurs between the other two tanks.
The author studied the subject and derived Eq. (4) as the fundamental differential equation to describe the behavior of the system.
By introducing the ratio 1≤γ₁, 0≤γ₃, γ₄ and 0≤γ₂≤1 into Eq. (4), various flow characteristics of this system were made clear. The calculated values thus obtained showed a fairly good agreement with the observed values obtained of five typical cases.

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Separation of gas mixtures by adsorption has become an important unit operation in the petrochemical industry. To design an apparatus for separating gas mixtures by adsorption, it is necessary to know the adsorption equilibria of gas mixtures.
Equilibria of adsorption, by active carbon, of various gas mixtures such as CO₂-C₂H₄, CO-CO₂, CO-C₂H₄, H₂-CO₂ and H₂-C₂H₄ were measured at various temperatures and total pressures. And equations expressing the isothermal adsorption of each component gas from these mixtures were examined.
Experimental
The binary adsorption equilibria were measured by using the apparatus shown in Fig. 1 (a). 1.2 or 4.0gr of active carbon was packed in a vessel, A, and the gas mixture was circulated through the bed of the adsorbent by means of a circulating pump, D. The circulating pump was equipped with a glass valve, E, having a piece of iron in it and with an electromagnet, F, through which intermittent direct current was sent. This intermittent direct current was obtained from the ordinary 100 volt alternative current by the use of a relay shown in Fig. 1 (b). After the adsorption reached the state of equilibrium, the gas composition in the adsorption system was measured with the interferometer, I, which was modified specially for use in vacuum system. The chamber volume of the interferometer was about 7.5cm³. The accuracy of the analysis varied with pressure, temperature and difference in refractivity of the two pure gases, and the errors at 0°C, calculated in terms of pressure, were as follows: 0.84mm Hg for CO₂-C₂H₄, 2.0mm Hg for CO-CO₂, 0.59mm Hg for CO-C₂H₄, 0.39mm Hg for H₂-C₂H₄, and 0.73mm Hg for H₂-CO₂. Material balance revealed the composition of the adsorbed phase.
The adsorption equilibria were measured at 0, 25, 30 and 50°C, and 200, 300, 450, 600 and 760mm Hg for CO₂-C₂H₄, CO-CO₂, CO-C₂H₄, H₂-C₂H₄ and H₂-CO₂ gas mixtures.
Results and Discussion
The relations among x-y equilibria for various gas mixtures are shown in Fig. 3 and in Table 1. From these experimental results was calculated the relative adsorptivity, α, in Eq. (7), which is employed as a measure of separability of these gasses as shown in Table 2.
In order to find out the equation of isothermal adsorption for the gas mixtures, it was examined, in the first place, whether the Markham-Benton Equation (Eqs. (1) and (2)) of the ideally mixed adsorption was applicable to the adsorption of these gases.
The adsorptions of CO₂ and C₂H₄ from CO₂-C₂H₄ gas mixture were expressed by the Markham-Benton Equation (Figs. 7 and 8). In the case of CO-CO₂ and CO-C₂H₄ gas mixtures, the adsorptions of CO₂ and C₂H₄ were expressed by Eq. (1), While the adsorption of CO could not be expressed by Eq. (1).
Consequently it was supposed that the adsorption of CO was affected by the presence of adsorbed molecules of CO₂ or C₂H₄. Therefore, Eq. (1) was empirically modified as follows:
(1) On the assumption that the adsorbed molecules of component B were already uniformly distributed on the surface, and that the extent of the adsorption of the component A were varied within a certain distance from the adsorbed molecules B by the repulsion or attraction forces of the adsorbed molecules B, Eq. (1) would be re-written as Eq. (8),
(2) On the assumption that the adsorbed molecules of B

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Two general rules were derived through the observation and investigation into the ternary vapor-liquid equilibrium data in the literature. They are presented as follows:
Rule 1. In any ternary system containing components, A, B and C, the presence of high concentration of any arbitrarily selected component, say C, results in the relative volatility of component, A to B, remaining constant over a wide range of concentration ratio between A and B. Three typical examples are shown in Figs. 3, 4 and 5 and in Table 1.
Rule 2. In any ternary system containing components, A, B and C, the relative volatility of component, A to B, in the presence of high concentration of any arbitrarily selected component, C, expressed by (α_{AB, C})_xC→1, is nearly equal to the ratio of (α_AC)_xC→1 to (α_BC)_xC→1, which are relative volatilities in binary systems A-C and B-C at high concentration of component C. That is:
(α_{AB, C})_xC→1_??_(α_AC)_xC→1/(α_BC)_xC→1
Some examples are shown in Table 2 and in Fig. 6.
By using these rules, the third component to be added to the binary system may be selected easily for the extractive distillation.

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