Gel potting method and method to reduce twinning for filtering hollow fibre membranes

Abstract

To pot membranes in a header, a dense, viscous liquid, suspension or, preferably, a thixotropic, water soluble gel, is placed in a header pan in space reserved for a permeate channel. A plurality of hollow fibre membranes are collected together and their open ends are inserted into the gel. A fixing liquid, typically a resin, is placed over the gel. The fixing liquid surrounds each membrane and then solidifies, simultaneously sealing the outer surfaces of the membranes and forming a plug in the opening of the header to complete the permeate channel. After the fixing liquid has solidified, the gel is removed by various means. The space initially occupied by the gel becomes part of the permeate channel after the gel is removed. In one embodiment, membranes are grouped by a cushioning adhesive which later surrounds the membranes where they exit the completed header.

We claim:  
     
         1 . A method of potting filtering hollow fibre membranes in a header, cap or end of a module comprising the steps of: 
 (a) collecting a plurality of hollow fibre membranes together;    (b) inserting ends of the membranes into a fugitive potting liquid, suspension or gel in a container, the fugitive potting liquid, suspension or gel having sufficient viscosity to not wick up the fibres significantly and sufficient density to not float on top of a fixing liquid to be placed in the container above the fugitive potting liquid;    (c) placing fixing liquid in the container over the fugitive potting liquid, suspension or gel which fixing liquid surrounds each membrane and then becomes a solid sealingly connected to the outside of each membrane but not blocking the lumens of the membranes;    (d) separating the fugitive potting liquid, suspension or gel from the fixing liquid after the fixing liquid has solidified;    (e) opening the ends of the membranes; and,    (f) attaching the solidified fixing liquid to a header pan, cap or end of a module in a position where the open ends of the membranes can be in fluid communication with a permeate channel in the header.    
     
     
         2 . The method of  claim 1  wherein the fugitive potting liquid, suspension or gel is a gel.  
     
     
         3 . The method of  claim 2  wherein the ends of the membranes are opened before the ends of the membranes are inserted in to the gel.  
     
     
         4 . The method of  claim 3  wherein 
 (a) the container is the header pan, cap or end of a module and the gel is placed in the header pan, cap or end of a module before the open ends of the membranes are inserted into the gel;  
 (b) the solidified fixing liquid is attached to the header pan, cap or end of a module by solidifying the fixing liquid in the header pan;  
 (c) the gel is separated from the fixing liquid after the fixing liquid has solidified by removing the gel from the header pan, cap or end of a module; and,  
 (d) the space initially occupied by the gel becomes part of the permeate channel after the gel is removed.  
 
     
     
         5 . The method of  claim 4  wherein the hollow fibre membranes have an outside diameter of about 1 mm or less.  
     
     
         6 . The method of  claim 4  wherein the hollow fibre membranes are collected together into a bundle in which they are randomly arranged.  
     
     
         7 . The method of  claim 5  wherein the hollow fibre membranes are collected together into a bundle in which they are randomly arranged.  
     
     
         8 . The method of  claim 4  wherein the gel is soluble in water and the gel is removed in part by dissolving the gel in water.  
     
     
         9 . The method of  claim 4  wherein the membranes are arranged into a group of closely spaced apart membranes before inserting their open ends into the gel.  
     
     
         10 . The method of  claim 4  wherein the gel is heated to assist in placing the gel in the header.  
     
     
         11 . The method of  claim 4  wherein the gel is heated to assist in removing the gel.  
     
     
         12 . The method of  claim 4  wherein the fixing liquid is a resin which continues to cure after it has solidified and a substantial portion of the gel is removed by flowing it out of the header while the resin cures.  
     
     
         13 . The method of  claim 7  wherein the gel is heated to assist in placing the gel in the header.  
     
     
         14 . The method of  claim 7  wherein the gel is heated to assist in removing the gel.  
     
     
         15 . The method of  claim 7  wherein the fixing liquid is a resin which continues to cure after it has solidified and a substantial portion of the gel is removed by flowing it out of the header while the resin cures.  
     
     
         16 . A method of potting filtering hollow fibre membranes in a header comprising the steps of: 
 (a) collecting a plurality of hollow fibre membranes together;    (b) inserting ends of the membranes into a thixotropic material in a container, the thixotropic material having sufficient viscosity to not wick up the fibres significantly and sufficient density to not float above a fixing liquid to be placed in the container above the thixotropic material;    (c) placing fixing liquid in the container over the thixotropic material which fixing liquid surrounds each membrane and then becomes a solid sealingly connected to the outside of each membrane but not blocking the lumens of the membranes;    (d) separating the thixotropic material from the fixing liquid after the fixing liquid has solidified;    (e) opening the ends of the membranes; and,    (f) attaching the solidified fixing liquid to a header pan, cap or end of a module in a position where the open ends of the membranes can be in fluid communication with a permeate channel in the header, cap or end of a module.    
     
     
         17 . The method of  claim 16  wherein the thixotropic material is a gel.  
     
     
         18 . The method of  claim 16  wherein the ends of the membranes are opened before the ends of the membranes are inserted in to the thixotropic material.  
     
     
         19 . The method of  claim 18  wherein 
 (a) the container is the header pan, cap or end of a module and the thixotropic material is placed in the header pan, cap or module before the open ends of the membranes are inserted into the thixotropic material;  
 (b) the solidified fixing liquid is attached to the header pan, cap or end of a module by solidifying the fixing liquid in the header pan;  
 (c) the thixotropic material is separated from the fixing liquid after the fixing liquid has solidified by removing the thixotropic material from the header pan, cap or end of a module; and,  
 (d) the space initially occupied by the thixotropic material becomes part of the permeate channel after the thixotropic material is removed.  
 
     
     
         20 . The method of  claim 19  wherein the thixotropic material is removed at least in part by vibrating it to a less viscous state.  
     
     
         21 . The method of  claim 16  wherein the thixotropic material is vibrated to assist in placing the thixotropic material in the header.