NOVELTY - A pervaporation process comprises passing a feed solution to be treated through a series of membrane modules (102, 103, 104, 105) that are housed in a single tube to separate the feed solution under pervaporation conditions into a residue stream (106) and a permeate stream. An inter-module reheating of the feed solution is achieved as it passes along the series by. The feed solution is flowed in the series at least partially back toward the feed end of that membrane module in a reheating zone.    USE - For separating a component from a liquid mixture, e.g. separation of aromatics from paraffins in an oil refinery, removal of organic sulfur compounds from hydrocarbon mixtures, dehydration of bioethanol, recovery of ethanol from fermentation broth, and removal of volatile organic compounds from wastewater.    ADVANTAGE - The vapor pressure of the component that it is desired to separate into the permeate stream is maintained at a lower level on the permeate side than on the feed side, and the pressure on the permeate side is such that the permeate is in the gas phase as it emerges from the membrane. The process results in a permeate vapor stream enriched in the desired component and a residue liquid stream depleted in that component. It avoids the need to extract the solution under treatment from the membrane module train to run it repeatedly through external heaters or heat exchangers. Not only does this provide better heat integration, but the large numbers of pipes, valves, flanges, and fittings associated with repeated removal and reintroduction are eliminated. The savings in engineering complexity and cost is achieved.    DETAILED DESCRIPTION - A pervaporation process involves passing a feed solution to be treated through a series of membrane modules (102, 103, 104, 105) having an outer longitudinal surface, a feed end, and a residue end, to separate the feed solution under pervaporation conditions into a residue stream (106) and a permeate stream. The membrane modules are housed in a single tube having an inside and an outside surface. An inter-module reheating of the feed solution is achieved as it passes along the series by. The feed solution exiting the residue end of a membrane module is flowed in the series at least partially back toward the feed end of that membrane module in a reheating zone defined by the outer longitudinal surface of that membrane module and the inside surface of the tube before the feed solution is permitted to enter the feed end of the next membrane module in the series. The outside surface of the tube is heated. An INDEPENDENT CLAIM is included for a pervaporation assembly.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic drawing of the flow pattern in a pervaporation process.    Membrane modules (102, 103, 104, 105)    Residue stream (106)    Reheating path (107, 108, 109, 110)    Treated solution (111)