Complex Model of the Efficiency of Rectification Plates. 6. Some Features of Applicability of Calculational Dependences

Abstract

The author assumes the interrelation of the distances from the site of injection of a vapor h and a liquid h ₁ to the surface of equality of the concentrations on ideal and real plates with a degree of deviation from the Raoult law that is characterized by the activity coefficient γ. If the activities of the components of ideal and real solutions coincide (γ = 1), then h = 0.5 and h ₁ = 0.5. With a positive deviation of a highly volatile component from the Raoult law (γ > 1), h > 0.5 and h ₁ > 0.5, with a negative deviation (γ < 1) — h < 0.5 and h ₁ < 0.5. The influence of the activity of a poorly volatile component and of both components on the indicated distances is also analyzed. In order to eliminate the negative values of the efficiency in calculational procedures, especially in countercurrent flow, it is proposed that the coefficient of equilibrium be found from the slope of a tangent to an equilibrium line to the X axis and that the length of a segment cut off by this tangent on the Y axis be taken into account. Some modifications of new dependences for concurrent flow, countercurrent flow, and cross flow with mixing and without it are given.