A device in a pipe has an annular partition spaced radially inwardly from an inner face of the pipe and defining therewith an upstream annular space opening axially upstream of the direction into the pipe such that a secondary gas stream is separated from the primary gas stream along with a liquid film on the inner surface, a downstream annular space larger than the upstream annular space, and a droplet separator opening into the downstream annular space. The separator has a plurality of lamellas, a condensate sump, and a drain, so that the edge film intercepted by the partition into the upstream space passes therefrom into the downstream space and therefrom through the separator such that the liquid of the film flows into the sump and out the drain and the secondary gas stream passes out of the separator.