Optimum Pressure for Total-Reflux Operated Thermal Diffusion Column for Isotope Separation

Abstract

A formula for prediction of the optimum operating pressure P opt of the thermal diffusion columns at total reflux is derived based on the approximate formulae for the column constants which can be evaluated analytically. The formula is expressed explicitly in terms Of (1) a parameter of cold wall radius r c, and physical properties (evaluated at the reference mean temperature T) of gases to be separated, or μD'R/r3 cMg, where μ: viscosity, D': product of diffusion coefficient at a standard pressure and the standard pressure, R: gas constant, M: molecular weight and g: gravitational acceleration, (2) ratio of radii δ between hot wire rh and rc, and (3) the ratio of the temperature difference ΔT to the cold wall temperature Tc, in the form The result is compared with experimental data; (1) binary monatomic gas systems, (2) multicomponent monatomic gas systems, (3) isotopically substituted polyatomic systems, (4) systems of low atomic or molecular weight, and (5) mixtures of unlike gases; mainly obtained by Rutherford & coworkers. Although the formula is based on the rather rough approximation for the column constants, the optimum pressures predicted by the present formula are in successfully good agreement with the experimental data even for the systems of low atomic or molecular weight and that of mixtures of unlike gases.