Title: Gas separator fixing structure and gas separating device using the same
Abstract: The gas separator fixing structure of the present invention is characterized in that it is provided with a gas separator 10 having a gas separation membrane 30 formed on at least one surface of a tubular support 31 having a through hole 7 in axial direction and comprising porous ceramics, a cap-like metal member 1 and a ring-shaped metal member 4 are fixed to one and the other open end of the gas separator 10 through seal members, respectively, and seal members are gland packings 11 and 12. A gas separating device can be provided in which there hardly occurs breakage of the tubular support constituting the gas separator 10 due to the thermal stress and there hardly occurs reduction of air-tightness between the gas separator 10 and the supporter supporting the gas separator caused by load of heat cycles, and besides which can be used even under the conditions of high temperatures.
Patent Number: 6,958,087 Issued on 10/25/2005 to Suzuki
| Inventors:
|
Suzuki; Kenji (Nagoya, JP)
|
| Assignee:
|
NGK Insulators, Ltd. (Nagoya, JP)
|
| Appl. No.:
|
822131 |
| Filed:
|
April 9, 2004 |
Foreign Application Priority Data
| Oct 23, 2001[JP] | 2001-324411 |
| Current U.S. Class: |
96/10; 95/56; 96/8; 96/11 |
| Intern'l Class: |
B01D 053/22; B01D 071/02 |
| Field of Search: |
96/4,8,10,11
95/55,56
|
References Cited [Referenced By]
U.S. Patent Documents
| 2671337 | Mar., 1954 | Hulsberg.
| |
| 3437357 | Apr., 1969 | Rubin.
| |
| 3761382 | Sep., 1973 | Hammond et al.
| |
| 5034125 | Jul., 1991 | Karbachsch et al.
| |
| 5131261 | Jul., 1992 | Tou et al.
| |
| 5614001 | Mar., 1997 | Kosaka et al.
| |
| 6139810 | Oct., 2000 | Gottzmann et al.
| |
| 6309444 | Oct., 2001 | Sims et al.
| |
| 6554015 | Apr., 2003 | Witt.
| |
| 2001/0013272 | Aug., 2001 | Blase et al.
| |
| 2001/0035093 | Nov., 2001 | Yokota.
| |
| Foreign Patent Documents |
| 56-24486 | Jun., 1981 | JP.
| |
| 56-48539 | Nov., 1981 | JP.
| |
| 58-204880 | Nov., 1983 | JP.
| |
| S62-273030 | Nov., 1987 | JP.
| |
| S63-171617 | Jul., 1988 | JP.
| |
| 03/120851 | May., 1991 | JP.
| |
Primary Examiner: Spitzer; Robert H.
Attorney, Agent or Firm: Burr & Brown
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation of International Application No. PCT/JP02/10961
having an international filing date of Oct. 22, 2002, which designated the United
States, the entirety of which is incorporated herein by reference.
This application also claims the benefit of Japanese Application 2001-324411,
filed Oct. 23, 2001, the entirety of which is incorporated herein by reference.
Claims
1. A gas separator fixing structure provided with a gas separator having a gas
separation membrane formed on at least one surface of a tubular support having
a through hole in axial direction and comprising porous ceramics, characterized
in that a cap-like metal member and a ring-shaped metal member are compression-fixed
to one and the other open end of the gas separator through seal members, respectively,
and seal members are gland packings.
2. A gas separator fixing structure according to claim 1, wherein the cap-like
metal member comprises a first cap-like or ring-shaped packing presser which gives
a tightening pressure to one of the gland packings in the axial direction of the
tubular support and a ring-shaped or cap-like lower stopper which inhibits movement
of the one of the gland packings, and the ring-shaped metal member comprises a
second ring-shaped packing presser which gives a tightening pressure to another
gland packing in the axial direction of the tubular support and a ring-shaped upper
stopper which inhibits movement of the another gland packing.
3. A gas separator fixing structure according to claim 2, wherein the first packing
presser has a convex shape which directly presses one of the gland packings by
us tip portion, and the lower stopper has a concave shape which directly contacts
with the one of the gland packings and fits to the convex shape of the first packing
presser, and the second packing presser has a convex shape which directly presses
another gland packing by its tip portion, and the upper stopper has a concave shape
which directly contacts with the another gland packing and can fit to the convex
shape of the second packing presser.
4. A gas separator fixing structure according to claim 2, wherein each of the
upper and lower stoppers have a bore passing at least partially thereibrough and
the bore has a first internal diameter for receiving the gland seal and a second,
larger internal diameter for receiving at least a portion of the packing presser.
5. A gas separator fixing structure according to claim 1, wherein the tubular
support has a plurality of through holes arranged in rows.
6. A gas separator fixing structure according to claim 1, wherein the maximum
value of operating temperature range of the gland packing is 300° C. or higher.
7. A gas separator fixing structure according to claim 1, wherein the maximum
value of operating temperature range of the gland packing in a non-oxidizing atmosphere
is 350° C. or higher.
8. A gas separator fixing structure according to claim 7, wherein the maximum
value of operating temperature range of the gland packing in a non-oxidizing atmosphere
is 600° C. or higher.
9. A gas separator fixing structure according to claim 1, wherein the main component
of the gland packings is expanded graphite.
10. A gas separator fixing structure according to claim 1, wherein the porous
ceramics is alumina.
11. A gas separator fixing structure according to claim 1, wherein the gas separation
membrane is a hydrogen separation membrane through which hydrogen selectively permeates.
12. A gas separator fixing structure according to claim 1, wherein the gas separation
membrane comprises palladium or a metal containing palladium.
13. A gas separator fixing structure according to claim 1, wherein the material
constituting the cap-like metal member and/or ring-shaped metal member has a thermal
expansion coefficient of 4×10
-6-10×10
-6/° C.
14. A gas separator fixing structure according to claim 1, wherein the material
constituting the cap-like metal member and/or ring-shaped metal member is Permalloy.
15. A gas separator fixing structure according to claim 1 which is used at a
temperature in the range of 250-1650° C.
16. A gas separator fixing structure according to claim 1 which is used at a
temperature in the range of 300-600° C.
17. A gas separator fixing structure according to claim 1 which is used under
a pressure of 0.1-10 MPa in the total pressure of the gas to be treated.
18. A gas separator fixing structure provided with a gas separator having a gas
separation membrane formed on at least one surface of a tubular support having
a through hole in axial direction and comprising porous ceramics, characterized
in that ring-shaped metal mewbers are fixed to both open ends of the gas separator
through seal members, respectively, and the seal members are gland packings.
19. A gas separator fixing structure according to claim 18, wherein the ring-shaped
metal member comprises a ring-shaped packing presser which gives a tightening pressure
to the gland packing in the axial direction of the tubular support and a ring-shaped
stopper which inhibits movement of the gland packing.
20. A gas separator fixing structure according to claim 19, wherein the ring-shaped
packing presser has a convex shape which directly presses the gland packing by
its tip portion, and the ring-shaped stopper has a concave shape which directly
contacts with the gland packing and can fit to the convex shape of the ring-shaped
packing presser.
21. A gas separating device comprising a gas separator fixing structure provided
with a gas separator having a gas separation membrane formed on at least one surface
of a tubular support having a through hole in axial direction and comprising porous
ceramics, wherein a cap-like metal member and a ring-shaped metal member are compression-fixed
to one and the other open end of the gas separator through seal members, respectively,
and seal members are gland packings, and being provided with a pressure container,
wherein the ring-shaped metal member is fixed to an inner surface of the pressure container.
22. A gas separating device comprising a gas separator fixing structure provided
with a gas separator having a gas separation membrane formed on at least one surface
of a tubular support having a through hole in axial direction and comprising ceramics,
wherein the gas separator fixing structure is fixed in a container having an inlet,
a first outlet and a second outlet,
wherein a specific gas component in a gas to be treated which flows into the
device from an inlet is allowed to permeate the gas separation membrane and to
flow out from the first outlet, and a gas which does not permeate through the gas
separation member is allowed to flow out from the second outlet, and
wherein ring-shaped metal members are fixed to both open ends of the gas separator
through seal members, respectively, and the seal members are gland packings.
23. A gas separating device according to claim 22 which is provided with a buffer
which absorbs expansion of the gas separator.
Description
TECHNICAL FIELD
The present invention relates to a gas separator fixing structure and a gas separating
device using the same.
BACKGROUND ART
Hitherto, for obtaining only a specific gas component from a multi-component
mixed gas, it has been known to use an organic or inorganic gas separation membrane.
As the separation membrane used for membrane separation method, there have been
known organic polymer membranes such as of polyimide and polysulfone as hydrogen
separation membranes and inorganic compound membranes such as palladium or palladium
alloy membranes. Particularly, palladium or palladium alloy membranes have heat
resistance and, furthermore, can give hydrogen of very high purity.
Palladium or palladium alloy membranes have property of permeating hydrogen
in the form of a solid solution, and utilizing this property, thin membranes of
palladium or palladium alloys are widely used as hydrogen separators for separating
hydrogen from a mixed gas containing hydrogen.
As to related conventional techniques, JP-A-62-273030 and JP-A-63-171617 disclose
a gas separator comprising a porous substrate, one surface of which is covered
with a gas separation membrane comprising palladium or a palladium alloy, in which
the porous substrate comprises ceramics such as glass and aluminum oxide. Since
the gas separation membrane alone is insufficient in mechanical strength, the gas
separation membrane is put on a porous substrate.
A gas separating device having the above gas separator incorporated therein has
a structure in which a gas to be treated is introduced from one side of the gas
separator, and only a specific gas permeates through the gas separator and purified
hydrogen gas is obtained from another side of the gas separator. Therefore, it
is important that the side of gas to be treated and the side of purified gas should
be air-tightly separated to inhibit leakage of the gas to be treated to the purified
gas side from the joint part of the gas separator and the support. On the other
hand, in order to efficiently separate hydrogen gas using a gas separator, it is
advantageous to carry out the separation at high temperatures and under high pressures,
namely, at 300° C. or higher, preferably 500° C. or higher under 5-20
atm for increasing the diffusion rate of hydrogen atom or the like through the
gas separation membrane.
In order to inhibit leakage of gas under the above conditions, generally the
gas
separator and the support are bonded with glass or brazing material (glass bonding,
brazing). Furthermore, when the gas treating temperature is lower than 250°
C., air-tightness between the gas separator and the support is ensured using an
O-ring made of resin or rubber.
However, when the gas separator and the support are bonded by the above-mentioned
glass bonding or brazing, there may be supposed occurrence of the problem that
the porous substrate constituting the gas separator is broken by thermal stress
or air-tightness between the gas separator and the support is lowered with loading
of heat cycles. Furthermore, not only the gas separator and the support must be
bonded with severely controlling the clearance between them, but also there may
occur the problem such as distortion caused by thermal stress because of the high
bonding temperature.
In the case of securing the air-tightness between the gas separator and the support
using an O-ring made of resin or rubber, when the treating temperature of gas is
higher than 250° C., it is substantially difficult to secure sufficient air-tightness,
and as a result, the range of operation temperature is restricted.
The present invention has been made in view of these problems in conventional
techniques, and the object of the present invention is to provide a gas separator
fixing structure and a gas separating device using the same in which the base which
constitutes the gas separator is hardly broken by thermal stress and the air-tightness
between the gas separator and a support supporting the gas separator is hardly
lowered, and which are usable under the conditions of high temperatures.
DISCLOSURE OF THE INVENTION
That is, according to the present invention, there is provided a gas separator
fixing structure provided with a gas separator having a gas separation membrane
formed on at least one surface of a tubular support having a through hole in axial
direction and comprising porous ceramics, characterized in that a cap-like metal
member and a ring-shaped metal member are fixed to one and the other open end of
the gas separator through seal members, respectively, and seal members are gland packings.
In the present invention, it is preferred that the cap-like metal member comprises
a first cap-like or ring-shaped packing presser which gives a tightening pressure
to one gland packing in the axial direction of the tubular support and a ring-shaped
or cap-like lower stopper which inhibits movement of the one gland packing, and
the ring-shaped metal member comprises a second ring-shaped packing presser which
gives a tightening pressure to another gland packing in the axial direction of
the tubular support and a ring-shaped upper stopper which inhibits movement of
the another gland packing.
In the present invention, it is preferred that the first packing presser has a
convex shape which directly presses one gland packing by its tip portion, and the
lower stopper has a concave shape which directly contacts with the one gland packing
and fits to the convex shape of the first packing presser, and the second packing
presser has a convex shape which directly presses another gland packing by its
tip portion, and the upper stopper has a concave shape which directly contacts
with the another gland packing and fits to the convex shape of the second packing presser.
Furthermore, according to the present invention, there is provided a
gas separator fixing structure provided with a gas separator having a gas separation
membrane formed on at least one surface of a tubular support having a through hole
in axial direction and comprising porous ceramics, characterized in that ring-shaped
metal members are fixed to both open ends of the gas separator through seal members,
respectively, and the seal members are gland packings.
In the present invention, it is preferred that the ring-shaped metal member comprises
a ring-shaped packing presser which gives a tightening pressure to the gland packing
in the axial direction of the tubular support and a ring-shaped stopper which inhibits
movement of the gland packing.
In the present invention, it is preferred that the ring-shaped packing presser
has a convex shape which directly presses the gland packing by its tip portion,
and the ring-shaped stopper has a concave shape which directly contacts with the
gland packing and fits to the convex shape of the ring-shaped packing presser.
In the present invention, it is preferred that the tubular support has a plurality
of through holes arranged in rows.
In the present invention, it is preferred that the maximum value of operating
temperature range of the gland packing is 300° C. or higher, and the maximum
value of operating temperature range of the gland packing in a non-oxidizing atmosphere
is 350° C. or higher, and more preferably 600° C. or higher.
Moreover, in the present invention, it is preferred that the main component
of the gland packings is expanded graphite and the porous ceramics is alumina.
Furthermore, in the present invention, it is preferred that the gas
separation membrane is a hydrogen separation membrane through which hydrogen selectively
permeates and the gas separation membrane comprises palladium or a metal containing palladium.
In the present invention, it is preferred that materials constituting the cap-like
metal member and/or ring-shaped metal member have a thermal expansion coefficient
of 10×10
-6/° C. or lower, and, furthermore, the materials
constituting the cap-like metal member and/or ring-shaped metal member are Permalloy.
The gas separator fixing structure of the present invention can be suitably used
at a temperature in the range of 250-1650° C., more preferably 300-600°
C. Moreover, it can be suitably used under a pressure of 0.1-10 MPa in the total
pressure of the gas to be treated.
Furthermore, according to the present invention, there is provided a
gas separating device provided with a pressure vessel, characterized in that the
ring-shaped metal member of any one of the above-mentioned gas separator fixing
structures is fixed to the inner surface of the pressure container.
According to the present invention, there is provided a gas separating
device in which a specific gas component in a gas to be treated which flows into
the device through an inlet is allowed to permeate through the gas separation membrane
and allowed to flow out from a first outlet, and the gas which does not permeate
the gas separation membrane is allowed to flow out from a second outlet, characterized
in that any one of the above-mentioned gas separator fixing structures is fixed
in the container having said inlet, said first outlet and said second outlet.
In the present invention, it is preferred that there is provided a buffer which
absorbs expansion of the gas separator.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view which shows one embodiment of the gas separator fixing
structure of the present invention,
FIG. 2 is a sectional view which shows another embodiment of the gas separator
fixing structure of the present invention,
FIG. 3 is a sectional view which shows further another embodiment of the gas
separator fixing structure of the present invention, and
FIG. 4 is a sectional view which shows one embodiment of the gas separating
device of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
The embodiments of the present invention will be explained below. These embodiments
should not be construed as limiting the invention in any manner, and changes and
modifications of designing may be made based on the usual knowledge of one skilled
in the art without departing from the spirit and scope of the present invention.
The first aspect of the present invention is a gas separator fixing structure
provided with a gas separator having a gas separation membrane formed on at least
one surface of a tubular support having a through hole in axial direction and comprising
porous ceramics, characterized in that a cap-like metal member and a ring-shaped
metal member are fixed to one and the other open end of the gas separator through
seal members, respectively, and the seal members are gland packings. Furthermore,
it is preferred that the cap-like metal member comprises a first cap-like or ring-shaped
packing presser which gives a tightening pressure to one gland packing in the axial
direction of the tubular support and a ring-shaped or cap-like lower stopper which
inhibits movement of the one gland packing, and the ring-shaped metal member comprises
a second ring-shaped packing presser which gives a tightening pressure to another
gland packing in the axial direction of the tubular support and a ring-shaped upper
stopper which inhibits movement of the another gland packing. These will be explained
in detail below.
FIG. 1 is a sectional view which shows one embodiment of the gas separator fixing
structure of the present invention. The cap-like metal member
1 comprises
a first cap-like packing presser
2 and a ring-shaped lower stopper
3,
and the ring-shaped metal member
4 comprises a second ring-shaped packing
presser
5 and a ring-shaped upper stopper
6. The ring-shaped metal
member
4 (the second packing presser
5) is bonded to a flange
8
having a through hole
7 by a bonding method which ensures air-tightness,
such as welding method.
The cap-like metal member
1 and the ring-shaped metal member
4
are provided with gland packings
11 and
12 as seal members in such
a manner that the gland packings contact with outer peripheral surface of the gas
separator
10. In this case, there may be provided stuffing boxes
13,
each of which can contain at least one of packings
11 and
12, and
the gland packings
11 and
12 are stored in the stuffing boxes
13.
However, it is necessary that the gland packings
11 and
12 directly
contact with the outer peripheral surface of the gas separator
10.
The first packing presser
2 and the second packing presser
5 can
give a tightening pressure to the gland packings
11 and
12 in the
axial direction of the tubular support
31, and the lower stopper
3
and the upper stopper
6 inhibit the movement of the gland packings
11
and
12 in axial direction caused by the application of tightening pressure
to the gland packings
11 and
12. In this case, the gland packings
11 and
12 inhibited from movement actually stick to the surface of
the gas separation member
30 under a proper pressure in the inner direction
of diameter of the gas separator
10, namely, in the direction perpendicular
to the membrane surface with undergoing some deformation, thereby securing the
air-tightness between the gas separator
10 and the cap-like metal member
1 and ring-shaped metal member
4. The tightening pressure given to
the gland packings
11 and
12 stored in the stuffing box
13
can be more effectively transferred to the gas separator
10 by the stuffing
box
13.
Furthermore, from the viewpoints of reducing the number of parts and
more easily securing the air-tightness, it is preferred that the first packing
presser
2 has a convex shape which directly presses the gland packing
11
by its tip portion, and the lower stopper
3 has a concave shape which directly
contacts with the gland packing
11 and fits to the convex shape of the first
packing presser
2, and the second packing presser
5 has a convex
shape which directly presses the gland packing
12 by its tip portion, and
the upper stopper
6 has a concave shape which directly contacts with the
gland packing
12 and fits to the convex shape of the second packing presser
5.
A thread groove
20 may be formed at the portion where the first packing
presser
2 and the lower stopper
3 contact with each other and at
the portion where the second packing presser
5 and the upper stopper
6
contact with each other in order to give a tightening pressure to the gland packings
11 and
12 and hold the tightening pressure. Moreover, in the peripheral
part of the first packing presser
2, the lower stopper
3, the second
packing presser
5 and the upper stopper
6, there may be formed a
chamfer
21 in order to make easy the screwing which is carried out using
a wrench or the like.
FIG. 2 is a sectional view which shows another embodiment of the gas separator
fixing structure of the present invention. The cap-like metal member
1 comprises
a first ring-shaped packing presser
100 and a ring-shaped lower stopper
107, and the ring-shaped metal member
4 comprises a second ring-shaped
packing presser
5 and a ring-shaped upper stopper
6. The ring-shaped
metal member
4 (the upper stopper
6) is bonded to a flange
8
having a through hole
7 by a bonding method such as welding method. Other
members, for example, gland packings
11 and
12, stuffing box
13,
etc. are disposed in the same positional relation as in the gas separator fixing
structure shown in FIG. 1, and the gland packings
11 and
12 directly
contact with the outer peripheral surface of the gas separator
10.
That is, in the gas separator fixing structure of the present invention, the
direction of the tightening pressure given to the gland packing by the first ring-shaped
packing presser may be any of upper and lower direction as far as it is axial direction
of the tubular support
31 as shown in FIG.
1 and FIG. 2, and free
design can be made depending on the purpose and use.
Next, the second aspect of the present invention will be explained. The second
aspect of the present invention is a gas separator fixing structure provided with
a gas separator having a gas separation membrane formed on at least one surface
of a tubular support having a through hole in axial direction and comprising porous
ceramics, characterized in that ring-shaped metal members are fixed to both open
ends of the gas separator through seal members, respectively, and the seal members
are gland packings. Furthermore, it is preferred that the ring-shaped metal member
comprises a ring-shaped packing presser which gives a tightening pressure to a
gland packing in the axial direction of the tubular support and a ring-shaped stopper
which inhibits movement of the gland packing. The detail of the second aspect will
be explained below.
FIG. 3 is a sectional view which shows further another embodiment of the gas
separator fixing structure of the present invention. The ring-shaped metal member
4 comprises ring-shaped packing pressers
110 and
120 and ring-shaped
stoppers
130 and
140, and the ring-shaped metal member
4 (ring-shaped
packing pressers
110 and
120) is bonded, by a bonding method such
as welding method, to a flange
8 having a through hole
7 or a vessel
body
104 to which the gas separator fixing structure is fitted.
The ring-shaped metal member
4 is provided with gland packings
11
and
12 as seal members in such a manner that the gland packings contact
with outer peripheral surface of the gas separator
10. In this case, there
may be provided stuffing boxes
13, each of which can contain at least one
of packings
11 and
12, and the gland packings
11 and
12
are stored in the stuffing boxes
13. However, it is necessary that the gland
packings
11 and
12 directly contact with the outer peripheral surface
of the gas separator
10.
The ring-shaped packing pressers
110 and
120 can give a tightening
pressure to the gland packings
11 and
12 in the axial direction of
the tubular support
31, and the ring-shaped stopper
130 and
140
inhibit the movement of the gland packings
11 and
12 in axial direction
caused by the application of tightening pressure to the gland packings
11
and
12. In this case, the gland packings
11 and
12 inhibited
from movement actually stick to the surface of the gas separation membrane
30
under a proper pressure in the inner direction of diameter of the gas separator
10, namely, in the direction perpendicular to the membrane surface with
undergoing some deformation, thereby securing the air-tightness between the gas
separator
10 and the ring-shaped metal member
4. The tightening pressure
given to the gland packings
11 and
12 stored in the stuffing box
13 can be more effectively transferred to the gas separator
10 by
the stuffing box
13.
Furthermore, from the viewpoints of reducing the number of parts and
more easily securing the air-tightness, it is preferred that the ring-shaped packing
pressers
110 and
120 have a convex shape which directly presses the
gland packings
11 and
12 by its tip portion, and the ring-shaped
stoppers
130 and
140 have a concave shape which directly contacts
with the gland packings
11 and
12 and can fit to the convex shape
of the ring-shaped packing pressers
110 and
120.
A thread groove
20 may be formed at the portion where the ring-shaped
packing
pressers
110 and
120 and the ring-shaped stoppers
130 and
140 contact with each other in order to give a tightening pressure to the
gland packings
11 and
12 and hold the tightening pressure. Moreover,
in the peripheral part of the ring-shaped packing pressers
110 and
120
and the ring-shaped stoppers
130 and
140, there may be formed a chamfer
21 in order to make easy the screwing which is carried out using a wrench
or the like.
As mentioned above, in the gas separator fixing structure shown in FIG. 3, the
direction of the tightening pressure given to the gland packing by the ring-shaped
packing presser may also be any of upper and lower directions as far as it is axial
direction of the tubular support, and free design can be made depending on the
purpose and use.
In the gas separator fixing structure of the present invention, the gas separator
is fixed to each metal member through a gland packing as a seal material without
utilizing glass bonding or brazing. Therefore, breakage of the gas separator caused
by difference in thermal expansion hardly occurs, and, furthermore, even when temperature
rises in real use of the gas separator, air-tightness is sufficiently secured and
the structure shows excellent endurance against load of heat cycles. Moreover,
there is no need to carry out increase of clamping of packing presser even at high
temperatures, and troubles of maintenance and examination can be diminished.
Moreover, in the present invention, the maximum value of operating temperature
range of the gland packing is preferably 300° C. or higher, more preferably
350° C. or higher, especially preferably 450° C. or higher. This is because
in order to increase diffusion rate of hydrogen atom or the like in a gas separation
membrane, it is preferred that the gas separator fixing structure can be used at
high temperatures. In the present invention, the upper limit of the maximum value
of the operating temperature range of the gland packing is not particularly limited,
and it may be about 1650° C. or lower from the viewpoints of substantial heat
resistance and the like.
Furthermore, in the present invention, the maximum value of operating
temperature range of the gland packing in a non-oxidizing atmosphere is preferably
350° C. or higher, more preferably 450° C. or higher, especially preferably
600° C. or higher. In the present invention, the upper limit of the maximum
value of the operating temperature range of the gland packing in a non-oxidizing
atmosphere is not particularly limited, and it may be about 1650° C. or lower
from the viewpoints of substantial heat resistance and the like.
Moreover, in the present invention, it is preferred that the main component
of the gland packing is expanded graphite. Since the gland packing mainly composed
of expanded graphite shows high heat resistance and high pressure resistance and
besides is an excellent elastic material, the air-tightness between the gas separator
and the cap-like metal member and ring-shaped metal member can be sufficiently
secured in the gas separator fixing structure of the present invention in which
the gland packing mainly composed of expanded graphite is used, and this gas separator
fixing structure can be used under the conditions of high temperature and high pressures.
In addition to the expanded graphite, asbestos fibers, metal fibers, etc. can
be mentioned as materials of packing which have such a heat resistance that the
maximum value of the operating temperature range is 300 or higher, but the asbestos
fibers are not preferred because they may adversely affect the human bodies (causing
troubles in health) and the metal fibers are not preferred because they may mar
the surface of gas separation membrane to which the packing is compression-fixed.
Therefore, these problems can be solved by using expanded graphite as the main
component of the gland packing.
The tubular support comprising porous ceramics which is one of the members constituting
the gas separator fixing structure of the present invention supports the gas separation
membrane because the gas separation member alone is low in mechanical strength.
The term "porous" here means, for example, having a large number of three-dimensionally
communicating fine pores, and the pore diameter is preferably 0.003-20 μm,
more preferably 0.005-5 μm. If the pore diameter is less than 0.003 μm,
resistance against passing of gas is high, and if the pore diameter exceeds 20
μm, pin holes are apt to be formed in the gas separation membrane, which
is not preferred.
In the present invention, the porous ceramics constituting the tubular support
is preferably alumina, with which the gas to be treated does not react. Furthermore,
the porous tubular support comprising alumina can be easily made to a desired shape,
and can be easily produced by a method disclosed, for example, in JP-A-62-273030.
In the present invention, it is preferred that the tubular support has a plurality
of through holes arranged in rows. However, the shape of the tubular support is
not limited to a columnar shape, and, for example, it may be of a square pillar,
and may be of a column or square pillar which is curved along its axis. Moreover,
shape of the through holes is not limited to linear shape, and may be of a curve.
Moreover, in the present invention, the gas separation membrane is preferably
a hydrogen separation membrane through which hydrogen is selectively permeated,
and metals which constitute the gas separation membrane which shows the selective
permeability are preferably palladium or metals containing palladium. The metals
containing palladium include palladium simple substance and palladium alloys. In
the case of the palladium alloys, content of the metal other than palladium is
preferably 10-30 mass % as mentioned in Journal of Membrane Science, 56(1991) 315-325:"Hydrogen
Permeable Palladium-Silver Alloy Membrane Supported on Porous Ceramics" and JP-A-63-295402.
The main object to make palladium alloyed is to protect palladium against hydrogen
embrittlement and to improve separation efficiency at high temperatures. Furthermore,
for protection of palladium against hydrogen embrittlement, it is preferred that
silver is contained as a metal other than palladium.
The surface covered with the gas separation membrane may be outer surface and/or
inner surface of the tubular support, and the method for covering the tubular support
with the gas separation membrane can be any generally known methods, and there
may be employed, for example, a chemical plating method, a vacuum evaporation method,
a sputtering method, etc.
In the present invention, it is preferred that the thermal expansion coefficient
of the material constituting the cap-like metal member and/or ring-shaped metal
member at a temperature within the range of operating temperature is preferably
10×10
-6/° C. or smaller, more preferably 9×10
-6/°
C. or smaller, and especially preferably 8×10
-6/° C. or smaller.
The thermal expansion coefficient of the tubular support comprising porous ceramics
is usually 10×10
-6/° C. or smaller because the thermal expansion
coefficient of the tubular support and that of cap-like metal member and/or ring-shaped
metal member are preferably close to each other from the viewpoints of control
of change in stress value of the gland packing and inhibition of breakage of the
tubular support. Therefore, leakage of the gas to be separated or breakage of the
tubular support under high temperature conditions can be inhibited by reducing
the thermal expansion coefficient of the cap-like metal member and/or ring-shaped
metal member to lower than the above value.
In the present invention, the lower limit of the thermal expansion coefficient
of the materials constituting the cap-like metal member and/or ring-shaped metal
member is not particularly limited, and they can be used without any problems when
the thermal expansion coefficient is about 0.4×10
-6/° C. or
higher from the viewpoint of easy availability of the materials.
Furthermore, as the suitable metals constituting the cap-like metal
member and/or ring-shaped metal member which have a thermal expansion coefficient
of 10×10
-6/° C. or lower, mention may be made of Permalloy,
Kovar, Invar, Super Invar, molybdenum, tungsten, iron-nickel alloys, etc., and
Permalloy is especially preferred. Thus, leakage of the gas to be separated or
breakage of the tubular support under high temperature conditions can be effectively inhibited.
An extremely small amount of gas to be treated (unseparated gas) which unavoidably
incorporates from the sealing face between the gas separator
10 and the
gland packings
11 and
12 is present in the separated gas which permeates
from the outer peripheral side to the inner peripheral side of the gas separator
10 (FIG.
1). However, considering the use of the resulting separated
gas, presence of an extremely small amount of the gas to be treated may be permitted
as far as the amount of the gas is such that the use of the separated gas is not
affected. For example, when it is supposed that the resulting separated gas is
hydrogen and is to be used for hydrogen purifier for fuel cells, 99 vol % or higher
is enough as the purity of the hydrogen gas.
Therefore, when the material of the cap-like metal member
1 and
the ring-shaped metal member
4 is SUS304 (thermal expansion coefficient:
17×10
-6/° C.), since the thermal expansion coefficient is
2-3 times that of the porous ceramics, leakage of the extremely small amount of
the gas to be treated is supposed to occur with decrease of stress of the gland
packings
11 and
12 under high temperature conditions, but the gas
separator fixing structure of the present invention can be suitably employed depending
on the use of the resulting separated gas (FIG.
1).
The gas separator fixing structure of the present invention is suitably usable
at a temperature in the range of 250-1650° C., and more suitably usable at
a temperature in the range of 300-600° C. due to its excellent endurance against
thermal stress or heat cycle. Moreover, it is suitably usable in the pressure range
of 0.1-10 MPa in total pressure of the gas to be treated.
Next, the third aspect of the present invention will be explained. The third
aspect of the present invention is a gas separating device provided with a pressure
container, characterized in that the ring-shaped metal member which is a part of
any one of the above-mentioned gas separator fixing structures is fixed to the
inner surface of the pressure container. The detail thereof will be explained below.
Explanation will be made taking the case where the gas separator fixing
structure shown in FIG. 1 is incorporated into the device. The ring-shaped metal
member
4, more specifically, a part of the second packing presser
5,
is bonded to the flange
8 or the like by a suitable bonding method such
as welding, whereby the ring-shaped metal member is fixed to the inner surface
of the pressure container (not shown) which is a constituting element of the gas
separating device. Since one of the open ends of the gas separator
10 is
air-tightly closed by the cap-like metal member
1 through the packing
11,
the separated gas which permeates through the gas separator
10 flows towards
the open end (through hole
7) to which the ring-shaped metal member
4
is fixed and is discharged from the pressure container. Other gases in the gas
to be treated do not permeate the gas separator and are discharged from an outlet
(not shown) provided at the pressure container.
Here, in the gas separating device of the present invention, the portion where
the gas separator fixing structure is fixed to the inner surface of the pressure
container is only the one end portion having through hole
7, and the cap-like
metal member
1, namely, another end, is not fixed to the inner surface of
the pressure container (FIG.
1). Therefore, there hardly occurs the breakage
due to the expansion and shrink of the gas separator which are caused by the load
of heat cycle, and there is exhibited the effect of being able to use the device
for a long period of time.
Next, the fourth aspect of the present invention will be explained. The fourth
aspect of the present invention is a gas separating device in which a specific
gas component in a gas to be treated which flows into the device through an inlet
is allowed to permeate through a gas separation member and to flow out from a first
outlet, and the gas which does not permeate through the gas separation member is
allowed to flow out from a second outlet, characterized in that any one of the
above-mentioned gas separator fixing structures in which the ring-shaped metal
members are respectively fixed to both open ends of the gas separator through seal
members is fixed in a container having said inlet, said first outlet and said second
outlet. The detail of the device will be explained below.
FIG. 4 is a sectional view which shows one embodiment of the gas separating
device of the present invention. In FIG. 4, the gas to be treated which is introduced
from an inlet
101 enters into the gas separator
10 from one end thereof
through the through hole
7 of the flange
8. The separated gas selectively
permeates through a gas separation member
30 and flows out of the gas separator
10, and flows out from an outlet
102. On the other hand, the gas
which does not permeate is discharged from another end of the gas separator
10
through an outlet
103. In FIG. 4, the reference numeral
105 indicates
a lid and
106 indicates a fixing member.
As mentioned above, in the case of introducing the gas to be treated from the
inside of the gas separator, when the gas to be treated is introduced from one
end of the gas separator and the gas which does not permeate is discharged from
the another end, it is necessary that one end of the gas separator is supported
inside the container body and besides both ends of the gas separator are allowed
to communicate with the outlet or the inlet of the container body. Therefore, there
is the possibility that the gas separating device is broken or the structure connecting
the gas separator with the outlet or the inlet of the container body is damaged
owing to the difference in thermal expansion of the gas separator and the container
body. In the present invention, it is preferred to provide a buffer which absorbs
the expansion of the gas separator, by which occurrence of the above problems can
be avoided.
Specifically, in order to inhibit the gas separating device from breaking
due to the difference in thermal expansion of the container body
104 and
the gas separator
10, the outer peripheral surface of the container body
104 may be provided with bellows to form a structure to permit extension
and contraction in the axial direction of the gas separator
10 as shown
in FIG.
4. The portion of the bellows undergoes a pressure of the permeating
gas, but the pressure of the permeating gas is generally low, namely, from negative
pressure to 0.2 MPa, and hence the force which extends the bellows can be ignored.
Moreover, there is another method of using a pipe having elasticity and
wound in the form of a spring for connecting the through hole with the outlet or
inlet of the container.
EXAMPLES
The present invention will be specifically explained by examples, which should
not be construed as limiting the invention in any manner.
(Gas Separator and Gas Separator Fixing Structure)
As a gas separator was used a porous tubular support which was made of alumina,
had an outer diameter of 10.7 mm, an inner diameter of 7.5 mm and a length of 40
mm and a small pore diameter of 0.1 μm, and was plated with metallic palladium
in a thickness of 18 μm. Furthermore, braided gland packings made of expanded
graphite were used as the gland packings constituting the gas separator fixing
structure and as the metal members, those made of 45 Permalloy were used. The thermal
expansion coefficients of the porous tubular support were 7.1×10
-6/°
C. (40-300° C.) and 7.7×10
-6/° C. (40-600° C.),
and those of the metal members were 7.3×10
-6/° C. (40-300°
C.) and 9.9×10
-6/° C. (40-600° C.).
(Production of Gas Separator Fixing Structure)
A gas separator fixing structure as shown in FIG. 1 was produced. First, two
of
the gland packings 11 and 12 were stored in the stuffing boxes 13,
respectively, and the first packing presser 2 and the second packing presser
5 were lightly screwed until they contacted with the gland packings 11
and 12, thereby tentatively fixing the gland packings 11 and 12.
Then, the above gas separator 10 was inserted into the cap-like metal member
1 and the ring-shaped metal member 4. In this case, the insertion
was carried out until the open ends of the gas separator 10 were positioned
deeper than the gland packings 11 and 12. Then, the first packing
presser 2 and the second packing presser 5 were fastened in by a
torque wrench so that the tightening pressure in axial direction reached 20 MPa
and the tightening pressure in inner direction of diameter (in the direction perpendicular
to the surface of the gas separation membrane) reached about 10 MPa, and thus a
gas separator fixing structure was produced.
(Air-Tightness Test)
The air-tightness test was conducted by fixing the above gas separator fixing
structure in a pressure container through a metal gasket.
The air-tightness test was conducted in the following manner. Argon gas was introduced
into the side of the gas separator which was to be treated (outer peripheral side)
under a pressure of 0.9 MPa and held therein. In this state, the gas separator
was heated from room temperature to 600° C. and then cooled to room temperature.
This temperature cycle was repeated 5 times, and flow rates of argon gas which
leaked to the separated gas side (inner peripheral side) at room temperature (25°
C.), 300° C. and 600° C. were measured. The results are shown in Table 1.
| |
TABLE 1 |
| |
| |
Flow rate of argon |
| |
gas (ml/min.) |
| |
Temperature of |
| |
measurement |
| |
Example |
25° C. |
300° C. |
600° C. |
| |
| |
Number |
1 |
0.4 |
0.1 |
0.3 |
| |
of |
2 |
0.7 |
0.4 |
0.3 |
| |
cycles |
3 |
0.8 |
0.4 |
0.3 |
| |
(times) |
4 |
1.0 |
0.5 |
0.4 |
| |
|
5 |
1.1 |
0.5 |
0.4 |
| |
(Discussion)
The permissible amount of the gas which leaks from the seal portion (permissible
amount of gas leaking from the seal portion) depends on the area of the separation
membrane, the amount of hydrogen permeating through the separation membrane, and
the amount of the gas to be treated permeating through pin holes of the separation
membrane. Taking these conditions into consideration, the permissible amount of
the gas leaking from the seal portion at 300° C. is assumed to be about 30
ml/min. In this case, as is clear from the results shown in Table 1, in the gas
separator fixing structure of the present invention, the amount of leaking argon
gas is extremely small even after being subjected to the temperature cycles, namely,
is reduced to about 1/60 (1/several tens) of the permissible amount of the gas
leaking from the seal portion, and a sufficient air-tightness is secured from low
temperature area (25° C.) to high temperature area (600° C.). Therefore,
it is considered that a gas separating device which is less in leakage of gas and
can be used for a long period of time can be provided by using the gas separator
fixing structure of the present invention.
Industrial Applicability
As explained above, in the gas separator fixing structure of the present invention,
a given metal member is fixed to an open end of the gas separator through a gland
packing, and hence there hardly occurs breakage of a tubular support constituting
the gas separator caused by thermal stress and reduction of air-tightness between
the gas separator and the metal member as a supporter supporting the gas separator
caused by load of heat cycles, and besides there is a merit that the gas separator
fixing structure can be used even under the conditions of high temperatures.
Furthermore, in the gas separating device of the present invention,
the above gas separator fixing structure is fixed to the inner surface of a pressure
container in a given state, and hence there hardly occurs breakage due to the expansion
and shrink of the gas separator caused by the load of heat cycles, and the device
can be used for a long period of time.
*
