Reverse-osmosis tubular membrane

In a membrane module for the separation of fluids by reverse osmosis or ultrafiltration, which module comprises:

• (a) a plurality of outer pressure-containing tubes having a one end and another end;
• (b) a plurality of membrane tubes containing a tubular membrane therein for the separation of fluids from a feed stream into a concentrate fraction and a permeate fraction, the membrane tubes having a one end and another end, the membrane tubes positioned within the outer tubes and spaced apart from the interior wall surface of the outer tubes, to define a thin, annular, axial, permeate-flow channel about the exterior wall of the membrane tubes;
• (c) tube-plate means at the one and the other ends of the module, to retain the one and the other ends of the outer tubes in a generally parallel, spaced-apart relationship, the plate means having an outer face and characterized by a plurality of tube passageways therein, to receive the one or the other ends of the membrane tubes, and characterized by a permeate-collection passageway therein having a permeate outlet, whereby permeate from each of the thin, annular, permeate-flow channels may be collected in the permeate-collection passageway and discharged from the permeate outlet;
• (d) generally U-shaped connecting means, to provide for fluid-flow communication between the membrane tubes at each end thereof, so as to permit serial flow between the membrane tubes of the module;
• (e) a feed inlet to provide for the introduction of a feed stream into the interior of the one or the other end of one of the membrane tubes;
• and
• (f) a feed outlet to provide for the withdrawal from the one or the other end of one of the membrane tubes of a concentrate fraction from the interior of the membrane tube, after serial-flow passage of the feed stream through the plurality of membrane tubes in the module, the improvement which comprises
• (i) a radial, permeate-collector cavity in the tube passageway of the plate means and at and surrounding the one and the other ends of the membrane tubes in the tube passageway,
• (ii) an open-mesh-material means, comprising a woven textile material of synthetic fibers, disposed in the annular, permeate channel and peripherally about the exterior surface of the membrane tubes, the open-mesh material extending into the tube passageway at the one and the other ends, to permit axial flow of the permeate toward the one or the other ends of the membrane tubes and into the radial, permeate-collector cavity at each end,
• (iii) a radial, permeate, channel passageway, the passageway extending directly radially outwardly from each collector cavity about the one or the other end of the membrane tubes to the permeate-collector passageway in the tube-plate means at the one or the other end,
• (iv) a resilient, generally T-shaped, grommet-sealing means extending into the interior of the membrane tubes at the one and the other ends thereof, the T-shaped head retained in a sealing relationship against the outer face of the tube-plate means,
• (v) the connecting means composed of a plurality of individual U-bend elements having extending skirt elements at the one and the other ends thereof, the skirt elements extending within the grommet-sealing means and into a close, sealing relationship therewith, and forcing the sealing grommet radially outwardly and into a close, sealing relationship with and against the interior of the membrane tubes in the tube passageway, but with a force insufficient to compact the open-mesh material peripherally surrounding the membrane tube in the tube passageway;
• (vi) backing means to force all of the U-bend elements, at the one or the other end of the tube-plate means, inwardly toward the outer face of each of the plate means and the T-shaped head of the grommet sealing against the outer face of the tube-plate means and into a sealing relationship,
• whereby permeate, which passes through the membrane tube, is collected in the annular, permeate-flow channel about the tube, flows axially toward one or the other end, or both ends, of the respective tubes, is collected in the radial, permeate-collector cavity at the end of the membrane tube, and flows from the permeate cavity through the radial, permeate passageway into the permeate-collection passageway of the tube-plate means.