Rotary reverse osmosis apparatus and method

Abstract

Reverse osmosis or ultrafiltration apparatus having first and second rotors revolving in the same direction about a central axis. The first rotor revolves at a higher speed and has an impeller which serves as a feed pump for the feed fluid. The second rotor revolves at lower speed and has a pressure vessel containing semi-permeable membranes which selectively permeate one component of a feed fluid, and has an integral diffuser casing for the feed pump. This arrangement reduces disc friction and diffuser hydraulic losses compared to conventional centrifugal machinery with stationary casings. The membranes are arranged so that centrifuge action within the rotating membrane assembly inhibits fouling and concentration polarization by differential buoyancy effects. The impeller can be centrifugal type with an externally surrounding diffuser, or it can be in an external impeller type enclosing a pitot tube pump type diffuser. Some embodiments include a centripetal energy recovery turbine for the concentrate fluid rejected by the membranes, the turbine runner being mounted on the first rotor remote from, or integral with, the impeller. Alternatively concentrate fluid energy can be recovered by using tangentially disposed nozzles mounted on the second rotor to discharge fluid backwards. Permeate fluid energy can be recovered from permeate nozzles ejecting permeate fluid against an impulse turbine mounted on a third rotor journalled to rotate about the axis at a speed of about one-half of the speed of the second rotor.

Dependencies are inferred from the claim text.