Patent attributes
A process is disclosed for shut-down of a membrane separation zone comprising a non-permeate side and a permeate side and processing a feed stream comprising a non-permeable component, a less-readily permeable, condensable component, and a readily permeable component. When the feed stream is not passed to the membrane separation zone, a purge stream is passed to the non-permeate side of the membrane separation to remove a residual gas stream and thereby prevent condensation of the less-readily permeable, condensable component upon depressurization and/or cooling of the membrane separation zone. This purge stream is provided by taking a feed stream, lowering its pressure which leads to cooling and then passing the cooled stream through a gas-liquid separator to removed condensed liquids. The need is reduced for oversizing membrane system which reduces treating costs and prevents permeate damage to membrane surfaces caused by condensation of less-readily permeable, condensable components such as C6+ hydrocarbons.
