Coiled membrane filtration system

Abstract

A method and apparatus for achieving reverse osmosis, microfiltration, nanofiltration and ultrafiltration, produces Dean vortices against a membrane surface which is advantageously in a form of a wound helical membrane tube.

Description

FIELD AND BACKGROUND OF THE INVENTIONThe present invention relates in general to filtration modules or elements, and in particular to a new and useful method and apparatus which utilizes a curved or coiled tubular membrane constructed to maximize the formation of Dean vortices at the solution-membrane interface, for improving the filtration effect.Most modular designs for pressure-driven membrane processes, such as reverse osmosis, ultrafiltration and microfiltration are based on maximizing membrane area per unit volume and on the handling convenience of the module. Many methods exist for reducing CP and fouling, including chemical modification of the membrane surface and physical methods such as scouring. Hydrodynamic methods are also known which rely on eddies during turbulent flow, or induced flow instabilities. Such instabilities can be created by introducing inserts into the flow path. Unstable flow across membranes have also been utilized to reduce solute build-up at the solut...

AI Technical Summary

Benefits of technology

The Dean vortex flow of the invention not only has similar advantages as Taylor vortex and oscillating flows but also is amenable to scale-up.

Problems solved by technology

The main limitations of this design are the difficulty in scaling-up membrane area and high energy consumption.

Both of these approaches show increased performance in the presence of vortices, but each has experienced some difficulties including scale-up and sealing problems.

Unfortunately, at low axial Reynolds numbers typically used in Poiseuille flow for most spiral wound units, this approach has been largely ineffective.

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