Patent ID: 7771569

Claim:
A method for enriching a light hydrocarbon mixture that includes propylene and propane, comprising: providing a vertically oriented distillation column having a bottom and a top, the distillation column having an entrance for vapor near the bottom of the distillation column and an exit for vapor near the top of the distillation column, the distillation column comprising a plurality of tubular membranes bundled in a parallel configuration, the tubular membranes being non-selective and having porous walls and a lumen, the porous walls capable of being wetted throughout by light hydrocarbon liquid, sending vapor of the light hydrocarbon mixture into the entrance and then upward through the distillation column and then through the exit, condensing vapor that exits to form a liquid, the liquid being enriched in propylene compared to the vapor that is sent through the entrance near the bottom of the distillation column sending at least a portion of the liquid that forms from the condensed vapor into the lumen of the tubular membranes at the top of the column wherein the liquid flows downward through the lumen of the tubular membranes while vapor continues to flow countercurrently upward through spaces in between the tubular membranes but not through the lumen, whereby an interface between vapor and liquid forms in the porous walls, wherein vapor near the top of the column becomes enriched in propylene and liquid near the bottom of the column becomes enriched in propane.