Method of forming tubesheet for hollow fibers

• US 5,192,478 A
• Filed: 01/15/1992
• Issued: 03/09/1993
• Est. Priority Date: 10/22/1984
• Status: Expired due to Fees

• Current Assignee: Cynara Co. (Schlumberger NV)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Caskey, Terrence L.
• Primary Examiner(s): AFTERGUT, KAREN K
• Application Number:
  US07/823,007
• Time in Patent Office: 419 Days
• Field of Search: 264/258, 264/259, 264/36, 264/139, 264/162, 264/251, 264/254, 264/255, 264/261, 264/263, 264/265, 264/135, 264/232, 264/234, 264/342, 264/344, 264/345, 264/DIG. 48, 165/173, 165/175, 34/9, 210/321.1, 210/323.1, 156/94
• US Class Current: 264/139
• CPC Class Codes: B01D 63/022 Encapsulating hollow fibres
• CPC Class Codes: B01D 63/0221 using a mould
• CPC Class Codes: B29C 2791/001 Shaping in several steps
• CPC Class Codes: B29C 70/845 by moulding material on a relative small portion of the preformed parts
• CPC Class Codes: B29K 2063/00 Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: Y10S 264/48 Processes of making filters

Abstract

Hollow fiber membranes can change dimensions upon drying or other processing creating leaks in tubesheets formed on fiber bundles. An adherent layer is formed in contact with an inner surface of each tubesheet and the fiber membranes therein in such a manner as to fill gaps formed between the hollow fiber membranes and each tubesheet during the drying or processing of the hollow fiber membranes and tubesheets. Preferably, the adherent layer is cast from a diglycidyl ether of bisphenol A containing an acrylo-nitrile-modified polyamine curing agent and the hollow fibers are cellulose ester.

Claims

1. A method of preparing a hollow fiber membrane device comprising sequentially:

(a) forming at least one tubesheet on a plurality of hollow fiber membranes, each of the hollow fiber membranes having a first end, a second end, and a lumen extending therebetween, the at least one tubesheet being in part defined by a first face proximate to and a second face remote from the first ends of the hollow fiber membranes,

(b) treating the hollow fiber membranes embedded in the tubesheet whereby the cross-section of the hollow fiber membranes shrink to cause gaps between the hollow fiber membranes and the tubesheet;

(c) casting a liquid resin on the second face of the tubesheet whereby the resin penetrates between the hollow fiber membranes and into the gaps; and

(d) curing the resin to form at least one normally solid adherent layer in intimate contact with the second face of the tubesheet and the hollow fiber membranes embedded in the tubesheet, so as to seal the gaps between the hollow fiber membranes and the tubesheet.

2. The method as described in claim 1 wherein the hollow fiber membranes are hollow fibers of cellulose ester, and water is removed from the fibers in the treatment step.

3. The method as described in claim 2 wherein the hollow fibers are disposed in an essentially parallel arrangement about a perforated core.

4. The method as described in claim 3 wherein the hollow fibers are embedded in two tubesheets, one at each end of the fibers.

5. The method as described in claim 2 wherein the hollow fibers are disposed as a plurality of helices about a perforated core.

6. The method as described in claim 5 wherein the hollow fibers are present as helices in opposing directions and a plurality of hollow fibers contact each other at oblique angles.

7. The method as described in claim 5 wherein the hollow fibers are embedded in two tubesheets, one at each end of the fibers.

8. The method as described in claim 6 wherein the hollow fibers are embedded in two tubesheets, one at each end of the fibers.

9. The method as described in claim 2 wherein an intermediate tubesheet is disposed on some intermediate region of the hollow fibers, such that the hollow fibers protrudes from at least two opposed faces of the intermediate tubesheet.

10. The method as described in claim 2 wherein the tubesheet is formed from an epoxy resin.

11. The method as described in claim 2 further comprising drying the surface of the hollow fibers in the region where the tubesheet is formed prior to forming the tubesheet.

12. The method as described in claim 2 wherein the hollow fibers are cellulose acetate.

13. The method as described in claim 2 wherein the hollow fibers are asymmetric cellulose triacetate consisting of from about 40 to about 44 weight percent acetate.

14. The method as described in claim 9 wherein an adherent layer is disposed on each face of the intermediate tubesheet from which hollow fibers protrude.

15. The method as described in claim 2 wherein the adherent layer comprises about 80 to about 100 parts by weight of epoxy resin, about 0 to about 20 parts by weight reactive diluent and an effective amount of a curing agent.

16. The method as described in claim 15 wherein the epoxy resin is a diglycidyl ether of bisphenol A.

17. The method as described in claim 16 wherein the curing agent is a cyanoethylated polyamine present in from about 15 to about 50 parts per hundred parts resin by weight.

18. The method as described in claim 1 further comprising machining the at least one tubesheet and adherent layer to remove the original tubesheet and expose fiber bores communicating through the adherent layer.