Enrichment calculations in gaseous diffusion: Large separation factor

A general method has been devised for calculating gaseous‐diffusion‐stage requirements to separate gases of widely differing molecular weights. For such a mixture the actual separation factor is shown to be less than the ideal separation factor, depending on the undiffused‐gas composition and the ratio of absolute pressures on each side of the barrier. The equilibrium relationship between the compositions of the diffused‐ and undiffused‐gas streams leaving any stage is also derived by means of the Rayleigh concept. Application of the method is illustrated with a diagram, like that of McCabe and Thiele for distillation, on which are stepped off the required number of theoretical stages to separate a particular hydrogen‐nitrogen mixture.