Selective clogging of failed fibers

• US 5,575,963 A
• Filed: 05/24/1994
• Issued: 11/19/1996
• Est. Priority Date: 06/01/1993
• Status: Expired due to Fees

• Current Assignee: AGA AB (Linde Plc), Rotek Industries Limited
• Original Assignee: AGA AB (Linde Plc), Rotek Industries Limited
• Inventors: Cohen, Haim, Soffer, Abraham, Saguee, Shlomo, Golub, Dan, Azariah, Moshe
• Primary Examiner(s): AFTERGUT, KAREN K
• Application Number:
  US08/248,331
• Time in Patent Office: 910 Days
• Field of Search: 264/36, 427/140, 156/94, 425/11-13
• US Class Current: 264/36.15
• CPC Class Codes: B01D 63/022 Encapsulating hollow fibres
• CPC Class Codes: B01D 63/0221 using a mould
• CPC Class Codes: B01D 65/108 Repairing membranes

Abstract

A method of selective clogging of failed hollow fibers of a membrane module, including a pack or bundle of fibers in a shell-side and bore-side arrangement which includes failed fibers and non-failed fibers, comprises the steps of: clogging bores of all of the fiber at one end of the pack or bundle of the fibers; substantially evacuating the membrane module both at the shell-side and at the bore-side; filling the bore-side and the shell-side with a non-permeant gas; subsequently-holding the membrane module vertically, disconnecting the bore-side of the membrane module from a supply of the non-permeant gas and dipping another end of the membrane module opposite to the clogged end into a reservoir containing a liquid sealant; applying a reduced pressure to the shell-side for a period of time sufficient to permit suction of sealant into the bores of the failed fibers through a failure of which vacuum is applied to the bore-side; allowing the sealant to solidify at least partially to clog the bores of both the failed fibers and the non-failed fibers; and cutting off a length of the bundle of the fibers such that the bores of the non-failed fibers are exposed while the bores of the failed fibers remain clogged.

Claims

1. A method of selective clogging of failed hollow fibers of a membrane module comprising a pack or bundle of fibers in a shell-side and bore-side arrangement, the pack or bundle comprising failed fibers together with a plurality of non-failed fibers, the method comprising the steps of:

clogging bores of all of the fibers at one end of the pack or bundle of the fibers;

substantially evacuating the membrane module both at the shell-side and at the bore-side;

filling the bore-side and the shell-side side with a non-permeant gas;

subsequently holding the membrane module vertically, disconnecting the bore-side of the membrane module from a supply of the non-permeant gas and dipping another end of the membrane module opposite to the clogged end into a reservoir containing a liquid sealant;

applying a reduced pressure to the shell-side for a period of time sufficient to permit suction of the liquid sealant into the bores of the failed fibers through a failure of which vacuum is applied to the bore-side;

allowing the sealant to solidify at least partially to clog the bores of both the failed fibers and the non-failed fibers; and

cutting off a length of the pack or bundle of the fibers such that the bores of the non-failed fibers are exposed while the bores of the failed fibers remain clogged with the sealant.

5. A method according to claim 1, wherein the liquid sealant being a low viscosity sealant is applied to the failed fibers having an inner diameter of at least 20μ

, without forcing a pressure difference, for the period of time such that a desired penetration depth, ranging from 0.5 to 10 cm, is achieved by capillary rise.

6. A method according to claim 1, wherein the liquid sealant is permitted to fill a bottom portion of the membrane module and to rise by virtue of capillarity, thereby expelling the non-permeant gas from the failed fibers and rising higher therein than in non-failed, non-permeant gas filled fibers.

7. A method according to claim 6, wherein the non-permeant gas is sulfur hexafluoride.

8. A method according to claim 1, further comprising a step of potting by dipping the membrane module into a liquid adhesive.

9. A method according to claim 1, further comprising the same steps repeated for the other end of the membrane module.

2. A method of selective clogging of failed hollow fibers of a membrane module comprising a pack or bundle of fibers in a shell-side and bore-side arrangement, the pack or bundle comprising failed fibers together with a plurality of non-failed fibers, the method comprising the steps of:

clogging bores of all of the fibers at one end of the pack or bundle of the fibers;

substantially evacuating the membrane module both at the shell-side and at the bore-side;

filling the bore-side and the shell side with a non-permeant gas;

subsequently holding the membrane module vertically, disconnecting the bore-side of the membrane module from a supply of the non-permeant gas and dipping another end of the membrane module opposite to the clogged end into a reservoir containing a liquid sealant;

applying a reduced pressure to the shell-side for a period of time sufficient to permit suction of the liquid sealant into the bores of the failed fibers through a failure of which vacuum is applied to the bore-side;

optionally, allowing the sealant to thicken, but not to solidify;

filling the shell-side with a permeant gas, whereby to cause the permeant gas permeating to the bore-side to expel the sealant from the non-failed fibers, thus opening up the bores of the non-failed fibers; and

allowing the sealant to solidify to clog the bores of the failed fibers.

3. A method according to claim 2, wherein the liquid sealant being a high viscosity, slow setting sealant is applied to the failed fibers having an inner diameter of at least 10 μ

, for the period of time of at least 0.1 minute, under a pressure difference Dp of at least 3 cm of water, until a penetration depth of at least 5 mm is achieved.

4. A method according to claim 2, wherein the liquid sealant being a high viscosity, fast setting sealant is applied to the failed fibers having an inner diameter of at least 10 μ

, for the period of time of at least 0.1 minute, under a pressure difference Dp of at least 3 cm of water, until a penetration depth of at least 5 mm is achieved.

10. A method according to claim 2, further comprising the same steps repeated for the other end of the membrane module.