Frameless array of hollow fiber membranes and method of maintaining clean fiber surfaces while filtering a substrate to withdraw a permeate

A gas-scrubbed assembly comprising, means for providing an alterative to a conventional module having plural individual arrays therewithin, including,

• a membrane device in combination with a gas-distribution means, to minimize build-up of particulate deposits on the surfaces of hollow fiber membranes in said device, and to recover permeate from a multicomponent liquid substrate, said assembly comprising, a frameless array of a bundle of said hollow fibers in a skein which is unsupported for operation in said substrate held at a pressure in the range from 1-10 atm, without being confined in a module's shell, the ends of said fibers being secured in first and second headers adapted to be mounted in spaced-apart relationship within said substrate and beneath said skein which is buoyantly swayable in said substrate, said first header having terminal end portions of a multiplicity of fibers sealingly secured in said first header, and said second header having opposed terminal end portions of said fibers sealingly secured in said second header, essentially all ends of said fibers being open so as to discharge permeate through said headers;
• said bundle comprising a multiplicity of fibers sealingly secured in closely-spaced-apart profusion and sealed with potting resin;
• liquid collection means secured in fluid-tight open communication with permeate-discharging faces of said headers;
• means for mounting said headers and liquid collection means for operation in said substrate;
• said gas-distribution means, located within a zone directly beneath said skein, having through-passages therein adapted to have sufficient gas flowed therethrough to generate enough bubbles flowing through said skein and around said fibers, so as to keep surfaces of said fibers awash with bubbles;
• and, means for withdrawing said permeate.

A system for withdrawing permeate from a multicomponent liquid substrate having particulate matter suspended therein, with a gas-scrubbed assembly comprising a frameless array of hollow fiber membranes (or "fibers") in combination with a gas-distribution means, said system comprising, means for providing an alterative to a conventional module having plural individual arrays therewithin, including,

• a reservoir for a volume of at least 100 liters of said substrate from which a permeate is to be withdrawn;
• a pair of headers adapted to be mounted in spaced-apart relationship within said substrate without being confined in a modular shell, a first header having terminal end portions of a multiplicity of fibers secured therein, and a second header having opposed terminal end portions of said fibers secured therein, essentially all ends of said fibers being open so as to discharge permeate through said headers, at least one header being disposed below a horizontal plane through the horizontal center plane of said one header;
• said fibers formed from a material selected from the group consisting of an inorganic material and an organic synthetic resinous material, and swayably buoyantly deployed in a body of said substrate, said fibers together having a surface area in excess of 10 m.sup.2, each fiber having a length >0.5 m and sufficiently greater than the direct distance between said first and second headers, so as to present, when said skein is deployed, a generally arcuate configuration above a plane through the horizontal center-line of a headers;
• collection means for collecting said permeate;
• means for mounting said spaced-apart headers in open fluid communication with said collection means;
• means for withdrawing said permeate;
• and,
• said gas-distribution means disposed within a zone beneath said skein, and adapted to generate bubbles which flow upwardly through said skein, whereby said fibers are kept awash in bubbles and resist the build-up of said particulate matter on the surfaces of said fibers.

A process for maintaining the outer surfaces of hollow fiber membranes essentially free from a build-up of deposits of particulate material while separating a permeate from a multicomponent liquid substrate in a reservoir, said process comprising, providing an alternative to a conventional module having plural individual arrays therewithin, by

• submerging a frameless array of fibers deployed as a skein within said substrate unconfined in a modular shell, said fibers being securely held in laterally opposed, spaced-apart first and second headers, said fibers having a transmembrane pressure differential in the range from about 0.7 kPa (0.1 psi) to about 345 kPa (50 psi), a total surface area >1 m.sup.2, and a length sufficiently greater than the direct distance between said first and second headers, so as to present said skein in a buoyantly swayable generally arcuate fiber configuration above a horizontal plane through the horizontal center-line of a header;
• mounting said headers in fluid-tight open communication with collection means to collect said permeate;
• flowing a fiber-cleansing gas through a gas-distribution means proximately disposed relative to said skein, within a zone directly beneath said skein, and contacting surfaces of said fibers with sufficient physical impact of bubbles of said gas to maintain essentially the entire length of each fiber in said skein awash with bubbles and essentially free from said build-up;
• maintaining an essentially constant flux through said fibers substantially the same as an equilibrium flux initially obtained after commencing operation of said process;
• collecting said permeate in said collection means;
• and, withdrawing said permeate.