Improving the Separation Efficiency of Liquid Thermal Diffusion Columns

Thermal diffusion in a flat‐plate column inclined for improved performance

“…The dotted line goes through the maxima of all the curves in good agreement with the data. Equation (11) requires that uL/K, be less than 2.52 or that u be less than 5.72 g./min. for the best angle of in- clination to exist.…”

“…However, since the convection brings down the fluid at the top of the column, where it is rich in one component, to the bottom of the column, where it is rich in the other component, and vice versa, there is a remixing of the two components, It appears, therefore, that proper control of the convective strength might effectively suppress this undesirable remixing effect while still preserving the desirable cascading effect, and thereby lead to improved separation. It has been found that separation can be improved by using packed or wired thermal diffusion columns (8, 11) in which the strength of convention was reduced. These columns, however, are handicapped by complication of the hydrodynamics of the system and by inflexibility to adjust for optimum convective strength for maximum separation.…”

Theoretical and experimental studies on the heavy water enrichment in concentric-tube Frazier-scheme thermal-diffusion columns under flow-rate fraction and plate spacing variations

“…Consequently, considerable effort has been expended on some improved columns with improvement of the separation efficiency by concerning both the operating techniques and the equipment. The enrichments obtained from these improved columns, such as inclined columns (Power and Wilke, 1957), wired columns (Washall and Molpolder, 1962), inclined moving-wall columns (Ramser, 1957), rotary columns (Sullivan et al, 1955), packed columns (Lorenz and Emery, 1959), rotary wired columns (Yeh and Ho, 1975), permeable barrier columns , impermeable barrier columns , plate spacing (Yeh, 1994) and sidestream operations (Ho and Chen, 2004), are somewhat better than that from the classical ClusiusDickel column.…”

Estimation of optimal performances in concentric-tube thermal diffusion columns of various devices

“…Many improved-separation methods have been developed by either suppressing the undesirable remixing effect or enhancing the desirable cascading effect, resulting in increased separation. It was found that the undesirable remixing effect can be reduced in inclined column (Chueh and Yeh, 1967;Powers and Wilke, 1957;Yeh, 1994), in a packed column (Lorenz and Emery Jr., 1959;Sullivan et al, 1955), and in a wired column (Washall and Molpolder, 1962;Yeh and Ward, 1971) while the desirable cascading effect can be enhanced in a moving-wall column (Ramser, 1957), and in a rotated wired column (Yeh and Ho, 1975;Yeh and Hsieh, 1983). Further, both cascading and remixing effects can be simultaneously adjusted in some optimal-design columns Yeh, 2001).…”

“…The experimental work reported by Washall and Molpolder (1962) was an attempt to increase the separation efficiency of bath-typewired thermal diffusion column by winding a wire within the annulus of the concentric-tube column. Both the wire diameter and the wire angle of inclination were critical factors affecting the maximum separation attainable.…”