Hollow-fiber membrane element and membrane module for forward osmosis
A hollow-fiber membrane element for forward osmosis which is a both open-ended hollow-fiber membrane element in which both ends of a wound hollow-fiber membrane body are opened, the wound hollow-fiber membrane body having hollow-fiber membranes arranged in an intersecting manner by winding the hollow-fiber membranes around a porous distribution pipe in a helical manner, wherein a) the number of winds per element length in a region from the outermost layer of the wound hollow-fiber membrane body to at least one eighth of the thickness of the wound hollow-fiber membrane body is 0.33 to 1.75, and b) the number of winds per element length in a region from the innermost layer of the wound hollow-fiber membrane body to at least one fourth of the thickness of the wound hollow-fiber membrane body is greater than 1.75.
1. A hollow-fiber membrane element for forward osmosis comprising a porous distribution pipe and a wound hollow-fiber membrane body which is a both open-ended hollow-fiber membrane arranged in an intersecting manner in which the hollow-fiber membranes are wound around the porous distribution pipe in a helical manner, wherein
a) the number of winds per element length in a region from an outermost layer of the wound hollow-fiber membrane body to at least one eighth of the thickness of the wound hollow-fiber membrane body is 0.33 to 1.75, and
b) the number of winds per element length in a region from an innermost layer of the wound hollow-fiber membrane body to at least one fourth of the thickness of the wound hollow-fiber membrane body is greater than 1.75.
2. The hollow-fiber membrane element according to claim 1 , wherein the number of winds per element length in a region from the outermost layer of the wound hollow-fiber membrane body to maximally three quarters of the thickness of the wound hollow-fiber membrane body is 0.33 to 1.75.
3. The hollow-fiber membrane element according to claim 1 , wherein element has an outer diameter greater than or equal to 130 mm.
4. The hollow-fiber membrane element according to claim 1 , wherein the hollow-fiber membrane is formed of at least one resin selected from the group consisting of a cellulose acetate resin, a polyamide resin, and a sulfonated polysulfone resin.
5. The hollow-fiber membrane element according to claim 1 , wherein the hollow-fiber membrane has an outer diameter of 160 to 270 μm.
6. The hollow-fiber membrane element according to claim 1 , wherein the wound hollow-fiber membrane body has an outer diameter of 130 to 420 mm, and a length of 0.2 to 1.6 m.
7. A hollow-fiber membrane module comprising a vessel and at least one hollow-fiber membrane element according to claim 1 charged in the vessel.
8. The hollow-fiber membrane module according to claim 7 , wherein the number of winds per element length in a region from the outermost layer of the wound hollow-fiber membrane body to maximally three quarters of the thickness of the wound hollow-fiber membrane body is 0.33 to 1.75.
9. The hollow-fiber membrane module according to claim 7 , wherein element has an outer diameter greater than or equal to 130 mm.
10. The hollow-fiber membrane module according to claim 7 , wherein the hollow-fiber membrane is formed of at least one resin selected from the group consisting of a cellulose acetate resin, a polyamide resin, and a sulfonated polysulfone resin.
11. The hollow-fiber membrane module according to claim 7 , wherein the hollow-fiber membrane has an outer diameter of 160 to 270 μm.
12. The hollow-fiber membrane module according to claim 7 , wherein the wound hollow-fiber membrane body has an outer diameter of 130 to 420 mm, and a length of 0.2 to 1.6 m.