For further enhancing foam drainage and comprehensive knowledge of the spiral internal component (SIC), the effects of its thread pitch and inclined angle were experimentally and theoretically investigated. The results showed that the decrease of the thread pitch, and the increase of the inclined angle contributed to more enhancement of foam drainage. Under batch conditions, the SDS enrichment ratio obtained with SIC of thread pitch 30 mm and inclined angle 30 was about 2.4 times of that obtained without SIC. The theoretical analyses predicted the liquid holdup distribution in the column with SIC and gave better explanations for the experimental results. It is found that the decrease of the thread pitch resulted in a larger number of the SIC units by which the more enhanced foam drainage was obtained. The increase of the inclined angle sped the reflux of the drained liquid, thus leading to faster decrease of the liquid holdup. However, the inclined angle had the weaker ability to enhance foam drainage than the thread pitch. (c) 2012 Elsevier B.V. All rights reserved.