Enhancing foam drainage by spiral internal components of different thread pitches and inclined angles and their applications to enrichment of SDS

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.

► Spiral internal components of varied thread pitches and inclined angles were designed.
► Their effects on foam drainage and foam fractionation performances were studied.
► The increased foam drainage by the spiral internal component was analyzed.
► Effects of the thread pitch and the inclined angle were theoretically analyzed.