A study of the separation efficiency of rotated concentric-tube thermal diffusion columns with helical plane inserted as a spacer in the annulus

The separation efficiency of rotated concentric-tube thermal diffusion columns with helical plane inserted as a spacer in the annulus was investigated with consideration of the curvature effect. It was found that the cascading effect could be effectively improved by rotating the tubes oppositely, while the remixing effect could be effectively reduced by employing a helical plane as a spacer, thereby leading to improved separation. Considerable improvement in separation was obtained by employing such column operating at the best tube-speed of rotation and the best wrapped angle of helical plane instead of using the stationary column without a helical plane. The equations for determination of the best value of wall distance and the highest separation in a batch-operated empty double-tube column were also derived.