Liquid purification or separation – Plural distinct separators – Filters
Reexamination Certificate
1999-03-09
2001-05-01
Kim, John (Department: 1723)
Liquid purification or separation
Plural distinct separators
Filters
C210S232000, C210S321770, C210S321860, C210S322000, C210S450000, C210S493100, C210S493400, C210S497100
Reexamination Certificate
active
06224767
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fluid separation element assembly, and more specifically to a fluid separation element assembly which is suitable for use in an apparatus for reverse osmosis, ultrafiltration or microfiltration.
2. Description of the Related Art
Generally, a spiral type fluid separation element assembly is formed, for example, as shown in FIG.
20
. In
FIG. 20
, a permeate carrier material
156
is disposed between a first separation membrane
154
and a second separation membrane
155
, the first separation membrane
154
and second separation membrane
155
are closed at three sides by, for example, an adhesive, and the remaining one side is opened in a direction toward a permeate collection tube
153
having permeate collection openings
152
to form an envelope member. A membrane unit
160
including this envelope member and a feed carrier material
157
is spirally wound around the permeate collection tube
153
. An anti-telescoping plate
158
is attached on the downstream-side end surface of the wound membrane unit
160
, a seal holder
159
is attached on the upstream-side end surface thereof, and a wrapping material
161
is formed on the periphery of the membrane unit
160
. As the seal holder
159
, generally the same plate as the anti-telescoping plate
158
is used.
In such a fluid separation element assembly
151
, feed water having entered from the side of seal holder
159
through a feed water passage
162
is separated to water
164
a
permeated through separation membranes
154
and
155
and the remaining feed water
164
b
during being passed through feed carrier material
157
. The permeated water
164
a
is discharged from the exit of permeate collection tube
153
, and the remaining feed water
164
b
(concentrated water) is discharged from the exit of anti-telescoping plate
158
, respectively. Anti-telescoping plate
158
prevents a telescoping deformation of fluid separation element
151
due to a pressure loss caused when feed water
163
passes through feed carrier material
157
. Anti-telescoping plate
158
and seal holder
159
are integrally combined with membrane unit
160
so that they are not easily harmed by the load originating from the pressure loss. Therefore, when fluid separation element
151
has deteriorated to a condition that it cannot further be used, for example, because of reduction of separation performance of the separation membrane, the members such as anti-telescoping plate
158
and permeate collection tube
153
are discarded without being reused, even if they are still usable.
On the other hand, a fluid separation element assembly having a detachable anti-telescoping plate is disclosed in U.S. Pat. No. 4,906,372. In the fluid separation element assembly, as shown in
FIG. 21
, because there is no means for preventing feed water from leaking toward the periphery side of a fluid separation element
151
from a gap between the fluid separation element
151
and an anti-telescoping plate
158
attached on the upstream-side end surface of the fluid separation element
151
, a net member
165
is provided on the periphery of the fluid separation element
151
.
In the fluid separation using such a conventional fluid separation element assembly, as shown in
FIG. 22
, fluid separation element
151
is contained in a pressure vessel
166
to be used as a fluid separation membrane module
167
. Net member
165
attached on the periphery of fluid separation element
151
is also contained, and the gap between pressure vessel
166
and fluid separation element
151
may be sealed. In this case, although net member
165
has elasticity, in order that the net member
165
is shrunk when it is inserted into pressure vessel
166
, it is necessary to carefully finish the accuracy of the diameter of fluid separation element
151
and the thickness of the net member
165
, depending upon the variable accuracy of the inner diameter of the pressure vessel
166
.
In practice, however, fluid separation element
151
undergoes a dispersion in its diameter more or less, depending upon a dispersion of the thickness of the member(s) used for the fluid separation element
151
. Because relatively many different kinds of members are used for fluid separation element
151
and a relatively large amount of them is used therefor, for example, in an 8 inch fluid separation element, there occurs a dispersion in the thickness of the diameter of the fluid separation element of 2 to 3 mm. When the diameter of fluid separation element
151
including net member
165
is smaller than the inner diameter of pressure vessel
166
, the net member
165
does not comes into contact with the pressure vessel
166
, and because the gap between the pressure vessel
166
and the fluid separation element
151
cannot be sealed, a relatively large amount of feed water
163
passes through the gap between the pressure vessel
166
and the fluid separation element
151
. As a result, the amount of feed water
163
passing along the surface of the separation membrane decreases, the concentration polarization on the surfaces of separation membranes
154
and
155
becomes great, and the amount of permeated water
164
a
decreases as well as the salt rejection performance in the membrane separation is greatly reduced. Particularly, in a process such as desalting of sea water in which the feed water has a high salt concentration, the affection due to the concentration polarization is great, the quality of the permeated water
164
a
is remarkably reduced.
It may be possible to increase the property of shrinkage of net member
165
by making the diameter of the portion of membrane unit
160
fairly smaller than the inner diameter of pressure vessel
166
in anticipation of the dispersion of the diameter of fluid separation element
151
, and by making the net member
165
thick. In this case, however, because it is necessary to make the portion of membrane unit
160
of fluid separation element
151
small, the effective membrane area becomes small, and the amount of water treated by the fluid separation element
151
is decreased.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a fluid separation element assembly which enables reuse of the fluid separation members, and which can appropriately prevent leakage of feed water and still ensure a large effective membrane area as well.
It is another object of the present invention to provide a fluid separation membrane module using such a fluid separation element assembly, which can achieve excellent performance.
To achieve the foregoing and other objects, a fluid separation element assembly according to the present invention comprises a fluid separation element having a membrane unit and a wrapping material formed around said membrane unit, the membrane unit being formed by a separation membrane, a permeate carrier material and a feed carrier material which are spirally wound around a permeate collection tube; an anti-telescoping plate attached to at least one end of the fluid separation element at a condition free to be detached; and feed water seal means for preventing feed water from leaking through a gap between the fluid separation element and the anti-telescoping plate.
The feed water seal means, for example, comprises a ring member provided on at least one end of the wrapping material and projecting in the axial direction of the fluid separation element. The ring member is preferably composed of a material having a flexural strength of 50 MPa or more. The ring member may be formed as either a ring formed integrally over the entire circumference or a divided ring having seams at positions in the circumferential direction of the ring member. The ring member preferably comes into contact with the anti-telescoping plate.
A separate seal ring, which works in combination with the feed water seal means, may be attached to a periphery of the anti-telescoping plate. The seal ring is preferably attached in a groove formed on
Fujino Hisaaki
Fujiwara Koji
Ikada Hiroyuki
Kim John
Miller Austin R.
Toray Industries Inc.
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