The equations for estimating the optimal column number and the corresponding maximum performance for deuterium recovery from H–D gas mixture by thermal diffusion in the forward-flow Frazier scheme of concentric-tube columns with the total sum of column heights fixed, have been derived. Considerable improvement in deuterium recovery is obtainable if the multi-column device with the optimal number of columns is employed, instead of using the single-column device, with the same total sum of column heights, especially for the case of higher volume flow-rate operation and larger total sum of column heights.
