U.S. patent application number 10/914101 was filed with the patent office on 2005-01-20 for apparatus for producing hydrogen.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES, LTD.. Invention is credited to Fujimoto, Yoshimasa, Kobayashi, Kazuto.
Application Number | 20050013754 10/914101 |
Document ID | / |
Family ID | 15754193 |
Filed Date | 2005-01-20 |
United States Patent
Application |
20050013754 |
Kind Code |
A1 |
Kobayashi, Kazuto ; et
al. |
January 20, 2005 |
Apparatus for producing hydrogen
Abstract
An apparatus for producing hydrogen by a steam reforming
reaction, on a catalyst, of a hydrocarbon or an oxygen-containing
hydrocarbon as a raw material is disclosed. The apparatus comprises
a hydrogen separation type reformer which has a means for heating
the catalyst and which has a hydrogen separation membrane built
into a layer of the catalyst for selectively separating hydrogen; a
cooling means for cooling high temperature high purity hydrogen
obtained from the reformer; and a hydrogen storage/delivery means
disposed downstream from the cooling means and composed of a
hydrogen occluding material.
Inventors: |
Kobayashi, Kazuto; (Tokyo,
JP) ; Fujimoto, Yoshimasa; (Hiroshima-shi,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES,
LTD.
|
Family ID: |
15754193 |
Appl. No.: |
10/914101 |
Filed: |
August 10, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10914101 |
Aug 10, 2004 |
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09588903 |
Jun 9, 2000 |
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6802876 |
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Current U.S.
Class: |
422/198 |
Current CPC
Class: |
B01D 53/229 20130101;
C01B 3/501 20130101; C01B 2203/1011 20130101; C01B 2203/148
20130101; Y02E 60/32 20130101; C01B 2203/0233 20130101; C01B
2203/0816 20130101; C01B 2203/1241 20130101; C01B 2203/1052
20130101; C01B 3/38 20130101; Y02P 30/30 20151101; C01B 2203/1223
20130101; C01B 2203/1633 20130101; Y02P 30/00 20151101; C01B
2203/82 20130101; C01B 2203/0883 20130101; C01B 2203/0811 20130101;
Y02P 20/128 20151101; C01B 2203/047 20130101; C01B 2203/0822
20130101; C01B 2203/0475 20130101; C01B 2203/0866 20130101; Y02E
60/327 20130101; Y02P 20/10 20151101; C01B 3/0005 20130101; C01B
2203/041 20130101; C01B 2203/0844 20130101; C01B 3/323
20130101 |
Class at
Publication: |
422/198 |
International
Class: |
B01J 008/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 9, 1999 |
JP |
11-162416 |
Claims
1.-17. (canceled)
18. An apparatus for producing hydrogen by a steam reforming
reaction, on a catalyst, of a hydrocarbon or an oxygen-containing
hydrocarbon as a raw material, comprising: a hydrogen separation
type reformer which has a means for heating the catalyst and which
has a hydrogen separation membrane built into a layer of the
catalyst for selectively separating hydrogen; a cooling means for
cooling high temperature high purity hydrogen obtained from the
reformer, wherein: the cooling means for cooling the high
temperature high purity hydrogen comprises an indirect heat
exchanger; wherein: a fluid for cooling the high temperature high
purity hydrogen via the indirect heat exchanger is one or both of a
raw material gas and combustion air to be fed to the hydrogen
separation type reformer; and a hydrogen charge/discharge means
disposed downstream from the cooling means and composed of a
hydrogen storage material, wherein: the hydrogen charge/discharge
means composed of the hydrogen storage material comprises at least
two members of a hydrogen storing alloy incorporating a
heating/cooling means.
19. An apparatus for producing hydrogen by a steam reforming
reaction, on a catalyst, of a hydrocarbon or an oxygen-containing
hydrocarbon as a raw material, comprising: a hydrogen separation
type reformer which has a means for heating the catalyst and which
has a hydrogen separation membrane built into a layer of the
catalyst for selectively separating hydrogen; a cooling means for
cooling high temperature high purity hydrogen obtained from the
reformer; wherein: the cooling means for cooling the high
temperature high purity hydrogen comprises an indirect heat
exchanger; wherein: a fluid for cooling the high temperature high
purity hydrogen via the indirect heat exchanger is one or both of
air or cooling water; and a hydrogen charge/discharge means
disposed downstream from the cooling means and composed of a
hydrogen storage material; wherein: the hydrogen charge/discharge
means composed of the hydrogen storage material comprises at least
two members of a hydrogen storing alloy incorporating a
heating/cooling means.
20. The apparatus for producing hydrogen as claimed in claim 18,
wherein: a pressure regulating means is interposed between the
cooling means for cooling the high temperature high purity hydrogen
and the hydrogen charge/discharge means disposed downstream from
the cooling means and composed of the hydrogen storage material, to
regulate the pressure of the high purity hydrogen to be fed to the
hydrogen charge/discharge means.
21. The apparatus for producing hydrogen as claimed in claim 19,
wherein: a pressure regulating means is interposed between the
cooling means for cooling the high temperature high purity hydrogen
and the hydrogen charge/discharge means disposed downstream from
the cooling means and composed of the hydrogen storage material, to
regulate the pressure of the high purity hydrogen to be fed to the
hydrogen charge/discharge means.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus for producing
hydrogen by a steam reforming reaction using a hydrocarbon or an
oxygen-containing hydrocarbon as a raw material.
[0003] 2. Description of the Related Art
[0004] A conventional apparatus for producing hydrogen with the use
of a hydrogen separation type reformer is proposed, for example, in
Japanese Unexamined Patent Publication No. 4-325402. Disclosed in
this proposal is an apparatus for producing hydrogen for a fuel
cell with the use of a hydrogen separation type reformer from which
hydrogen is withdrawn by a pressure reducing means. The concept of
constitution of this apparatus is illustrated in FIG. 9.
[0005] As shown in FIG. 9, a hydrogen separation membrane 02 and a
catalyst 08 are provided in a hydrogen separation type reformer 01.
A gas as a raw material (hereinafter referred to as a raw material
gas) 06 and steam 07 are fed to the hydrogen separation type
reformer 01, where a reforming reaction takes place. Hydrogen
formed by the reforming reaction is separated by the separation
membrane 02. On a hydrogen permeation side 03 where the separated
hydrogen permeates, a pressure reducing device 04 is provided to
recover high purity hydrogen 05.
[0006] With the hydrogen separation type reformer 01, the raw
material gas 06 comprising a hydrocarbon or an oxygen-containing
hydrocarbon such as methane or methanol is introduced, and reformed
on the catalyst 08 by a steam reforming reaction and a CO shift
reaction to form hydrogen and carbon dioxide mainly. The hydrogen
is selectively separated, for recovery, by the hydrogen separation
membrane 02 built into the catalyst 08. As the hydrogen separation
membrane 02, a non-porous thin film with a thickness as small as
about several to 50 .mu.m, which comprises a hydrogen-permeable
metal film of Pd or Pd alloy, is used, as shown in Japanese
Unexamined Patent Publication No. 6-321503. As the catalyst 08, a
catalyst containing a group VIII metal (Fe, Co, Ni, Ru, Rh, Pd or
Pt) is preferred, and a catalyst bearing Ni, Ru or Rh or an
NiO-containing catalyst is particularly preferred.
[0007] A perspective sectional view of the structure of a typical
hydrogen separation type reformer is shown in FIG. 7, and a cross
sectional view of the structure is shown in FIG. 8. As shown in
these drawings, a hydrogen separation type reformer 10 has an outer
tube 14 with a closed bottom 12, and an intermediate tube 16 and an
inner tube 18 disposed in this order inwardly of the outer tube 14.
The outer tube 14, the intermediate tube 16, and the inner tube 18
are each in the form of an upright cylinder. At an upper part of a
second annular space portion 26 between the intermediate tube 16
and the inner tube 18, a preliminary reforming portion 25 is
provided. Below the preliminary reforming portion 25, a plurality
of hydrogen permeable cylindrical tubes 34 having a metal film
selectively permeable to hydrogen are disposed concentrically with
the second annular space portion 26.
[0008] A burner 46 burns a fuel gas, which has been introduced
through a fuel gas pipe 48, with air taken in through an air intake
pipe 50 to supply thermal energy necessary for a steam reforming
reaction to the second annular space portion 26 filled with are
forming catalyst A, thereby keeping the catalyst at a predetermined
temperature. The fuel gas passes through an inner tube hollow
portion 22, a space between the bottom 12 of the outer tube 14 and
an annular bottom portion 24, and a first annular space portion 20,
and goes outside through a combustion gas outlet 52. During this
motion, the fuel gas heats a layer of the catalyst filled into the
second annular space portion 26.
[0009] A process feed gas comprising a gas mixture of steam and a
raw material gas composed of a hydrocarbon or an oxygen-containing
hydrocarbon, such as methane or methanol, is introduced through a
feed gas inlet 54 provided at an upper part of the second annular
space portion 26. The process feed gas is partially converted into
hydrogen at the preliminary reforming portion 25, and flowed into
the layer of the catalyst filled into the second annular space
portion 26, whereby the process feed gas is converted into hydrogen
at a high temperature. The resulting hydrogen is selectively
separated and collected by the hydrogen permeable cylindrical tubes
34, passed through a third space portion 33, and flowed out through
a hydrogen outlet 56 provided above the third space portion 33. The
unreacted raw material gas and the resulting CO and CO.sub.2 gases,
which have passed through the catalyst layer, flow through an
off-gas pipe 60 having an opening at a lower part of the second
annular space portion 26, and flow out of the system through an
off-gas outlet 62.
[0010] With the foregoing conventional apparatus, the resulting
hydrogen is withdrawn from the hydrogen separation type reformer 10
by a pressure reducing device. As is well known, a hydrogen
separation membrane gives a necessary amount of hydrogen with high
efficiency, accordingly, with a small membrane area, if the
pressure of the hydrogen permeation side is minimized. Thus, a
highly efficient pressure reducing device has been demanded. A
vacuum pump or the like is conceivable as a pressure reducing
device. However, such a rotary device has difficulty in efficiently
delivering a light gas, such as hydrogen, thus requiring a high
power. Furthermore, the aforementioned Japanese Unexamined Patent
Publication No. 4-325402 does not propose a concrete apparatus
layout including a pressure reducing device, and cannot actualize a
feasible apparatus.
SUMMARY OF THE INVENTION
[0011] The present invention has been accomplished in light of
these circumstances. It is an object of this invention to actualize
such a concrete and feasible apparatus layout involving a pressure
reducing device and provide an apparatus for producing hydrogen
with the use a hydrogen separation type reformer, the apparatus
having a minimal area required, and having improved durability
while using a pressure reducing device.
[0012] A first aspect of the present invention, as a means of
attaining the above object, is an apparatus for producing hydrogen
by a steam reforming reaction, on a catalyst, of a hydrocarbon or
an oxygen-containing hydrocarbon as a raw material, the apparatus
comprising a hydrogen separation type reformer which has a means
for heating the catalyst and which has a hydrogen separation
membrane built into a layer of the catalyst for selectively
separating hydrogen, a cooling means for cooling high temperature
high purity hydrogen obtained from the reformer, and a hydrogen
storage/delivery means disposed downstream from the cooling means
and composed of a hydrogen occluding material.
[0013] According to the first aspect of the invention, the
following actions and effects are exhibited:
[0014] The high temperature high purity hydrogen that has been
separated from the reformer is once cooled by the cooler, the
indirect heat exchanger, to a temperature at which hydrogen is
easily occluded in the hydrogen occluding material. Then, the
cooled hydrogen is fed to the hydrogen occluding material. As a
result, the hydrogen occlusion rate and the amount of hydrogen
occlusion are increased, and hydrogen can be withdrawn from the
reformer at a lower pressure than the atmospheric pressure. Thus,
the membrane area of the hydrogen separation membrane can be
decreased. Moreover, a required power can be decreased markedly in
comparison with the power required for the use of a vacuum
pump.
[0015] When hydrogen stored in the hydrogen occluding material is
to be delivered, the temperature of the hydrogen occluding material
is set at an appropriate level, whereby high pressure hydrogen can
be obtained. Thus, a hydrogen compression power necessary when a
compressor is used can be cut down markedly.
[0016] A second aspect of the invention is the apparatus for
producing hydrogen as the first aspect of the invention, wherein
the cooling means for cooling the high temperature high purity
hydrogen comprises an indirect heat exchanger.
[0017] According to the second aspect of the invention, the
sensible heat of the high temperature high purity hydrogen can be
utilized for heating of the raw material gas and steam. Thus, the
energy efficiency of the apparatus can be increased.
[0018] A third aspect of the invention is the apparatus for
producing hydrogen as the first or second aspect of the invention,
wherein a fluid for cooling the high temperature high purity
hydrogen via the indirect heat exchanger is one or both of a raw
material gas and combustion air to be fed to the hydrogen
separation type reformer. As the raw material gas, a mixture of a
hydrocarbon or an oxygen-containing hydrocarbon can be named.
[0019] According to the third aspect of the invention, it becomes
unnecessary to use cooling water, separately, for heat exchange.
Also, preheating increases the reforming efficiency, and can
improve the thermal efficiency of the entire apparatus.
[0020] A fourth aspect of the invention is the apparatus for
producing hydrogen as any one of the first to third aspects of the
invention, wherein a fluid for cooling the high temperature high
purity hydrogen via the indirect heat exchanger is one or both of
air or cooling water.
[0021] According to the fourth aspect of the invention, the
sensible heat of the high temperature high purity hydrogen can be
recovered and utilized.
[0022] A fifth aspect of the invention is the apparatus for
producing hydrogen as any one of the first to fourth aspects of the
invention, wherein the hydrogen storage/delivery means composed of
the hydrogen occluding material comprises at least two members of a
hydrogen storing alloy incorporating a heating/cooling means.
[0023] According to the fifth aspect of the invention, efficient
occlusion of hydrogen can be performed.
[0024] A sixth aspect of the invention is the apparatus for
producing hydrogen as the fifth aspect of the invention, wherein a
fluid for cooling the high temperature high purity hydrogen via the
indirect heat exchanger is cooling water, and hot water heated by
heat exchange performed by the heat exchanger is used for heating
of a hydrogen delivery means in the hydrogen storage/delivery means
composed of the hydrogen occluding material.
[0025] According to the sixth aspect of the invention, cooling
water used to cool high temperature high purity hydrogen is
utilized for heating the hydrogen occluding material. Thus,
effective use of heat can be achieved.
[0026] A seventh aspect of the invention is the apparatus for
producing hydrogen as any one of the first to sixth aspects of the
invention, wherein a pressure regulating means is interposed
between the cooling means for cooling the high temperature high
purity hydrogen and the hydrogen storage/delivery means disposed
downstream from the cooling means and composed of the hydrogen
occluding material, to regulate the pressure of the high purity
hydrogen to be fed to the hydrogen storage/delivery means.
[0027] According to the seventh aspect of the invention, the
pressure regulator is installed between the hydrogen occluding
material and the cooling means. This prevents a rapid decrease in
pressure on the hydrogen permeation side of the hydrogen separation
membrane, thus improving the durability of the hydrogen separation
membrane. Moreover, a rapid rise in the temperature of the hydrogen
occluding material associated with its hydrogen occlusion can also
be prevented. Thermal shock to the hydrogen occluding material can
be lessened. Furthermore, changes over time in the amount of
hydrogen production from the apparatus for producing hydrogen can
be minimized and leveled off.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The above and other objects, features and advantages of the
present invention will become more apparent from the following
description taken in connection with the accompanying drawings, in
which:
[0029] FIG. 1 is a schematic view of a first embodiment of the
present invention;
[0030] FIG. 2 is a schematic view of a second embodiment of the
invention;
[0031] FIG. 3 is a schematic view of a third embodiment of the
invention;
[0032] FIG. 4 is a schematic view of a fourth embodiment of the
invention;
[0033] FIG. 5 is a schematic view of a fifth embodiment of the
invention;
[0034] FIG. 6 is a graph of changes in the pressure of low
temperature high purity hydrogen during hydrogen occlusion;
[0035] FIG. 7 is a perspective sectional view of an apparatus for
producing hydrogen;
[0036] FIG. 8 is a schematic cross sectional view of the apparatus
for producing hydrogen shown in FIG. 7; and
[0037] FIG. 9 is a schematic view of a conventional apparatus for
producing hydrogen.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] Embodiments of the present invention will now be described
in detail with reference to the accompanying drawings, which in no
way limit the invention.
[0039] [First Embodiment]
[0040] FIG. 1 is a schematic view of an apparatus layout for
implementing the present invention. As shown in FIG. 1, an
apparatus for producing hydrogen according to the present
embodiment is an apparatus for producing hydrogen by a steam
reforming reaction, on a catalyst, of a hydrocarbon or an
oxygen-containing hydrocarbon as a raw material, the apparatus
comprising a hydrogen separation type reformer 100 which has a
means for heating the catalyst and which has a hydrogen separation
membrane built into a layer of the catalyst for selectively
separating hydrogen, a cooler 106 for cooling high temperature high
purity hydrogen obtained from the reformer 100, and a hydrogen
storage/delivery means 108 disposed downstream from the cooler 106
and composed of a hydrogen occluding material.
[0041] The hydrogen separation type reformer (hereinafter referred
to as "reformer") 100 may be, but not restricted to, one having a
structure as shown in FIGS. 7 and 8. In the following description,
the same reference numerals as used in the apparatus shown in FIGS.
7 and 8 will be used, and overlapping explanations of the
constitution of the apparatus will be omitted.
[0042] The reformer 100 is supplied with a raw material gas 101,
which comprises a hydrocarbon or an oxygen-containing hydrocarbon
such as methane or methanol, and steam 102. These materials are
reformed mainly by a steam reforming reaction to form a mixed gas
mainly composed of hydrogen, carbon monoxide and carbon dioxide.
Hydrogen in this gas is selectively separated, and withdrawn from
the reformer 100 as high temperature (400 to 550.degree. C.) high
purity hydrogen 103. The residual gas after separation of hydrogen
is taken out of the reformer 100 as an off-gas 104. The off-gas 104
is fed to a combustion side of the reformer 100, mixed with
combustion air 105 in a burner of the reformer 100 (the burner 46
of the reformer shown in FIG. 7), and then subjected to combustion.
Alternatively, the off-gas 104 may be mixed with a portion 101a of
the raw material gas 101 supplied, and then may be used as
fuel.
[0043] The high temperature high purity hydrogen 103 separated from
the reformer 100 is cooled by the cooler 106 to become low
temperature (30 to 200.degree. C.) high purity hydrogen 107. This
hydrogen 107 is stored in the hydrogen storage/delivery means 108
composed of a hydrogen occluding material, and delivered from the
hydrogen storage/delivery means 108 as high pressure hydrogen (2
atm or higher) 109. The low temperature high purity hydrogen 107
contains trace amounts of impurities such as carbon dioxide and
carbon monoxide. Therefore, the low temperature high purity
hydrogen 107 during storage or delivery is intermittently sent to
the reformer 100 as purge hydrogen 110a for use as part of fuel.
When the low temperature high purity hydrogen 107 is not sent to
the reformer 100, it is discharged out of the system as low purity
hydrogen 110b.
[0044] In the cooler 106 of the present First Embodiment, a gas
mixture 111 of the raw material gas 101 and steam 102 is heat
exchanged with the high temperature high purity hydrogen 103
indirectly, and thereby preheated. The preheated gas mixture 111 is
supplied to the reformer 100.
[0045] The hydrogen occluding material of the hydrogen
storage/delivery means 108 for carrying out the invention may be
any material, without being restricted to the one disclosed in the
embodiment, as long as it selectively occludes hydrogen from the
mixed gas containing hydrogen, and releases the occluded hydrogen
upon heating. As a practical hydrogen occluding material, a
hydrogen storing alloy is known. Its examples are rare earth
metal-Ni alloys such as LaNi.sub.5, misch metal alloys,
titanium-zirconium alloys such as TiFe, Mg alloys such as
Mg.sub.2Ni, V alloys, and calcium alloys such as CaNi.sub.5. In the
invention, the hydrogen occluding material is not restricted to
these alloys. Occluding materials which occlude hydrogen, such as
those composed of a carbon nanotube, are also usable.
[0046] As the indirect type heat exchanger for the cooler 106, an
ordinary shell & tube type heat exchanger or an ordinary plate
type heat exchanger can be used. Any type of heat exchanger, which
can perform cooling without direct contact with the high
temperature high purity hydrogen 103, can be used without its
embodiment being restricted.
[0047] According to the present embodiment, the high temperature
(400 to 550.degree. C.) high purity hydrogen 103 that has been
separated from the reformer 100 is once cooled by the cooler 106,
the indirect heat exchanger, to a temperature of about 30 to
200.degree. C. at which hydrogen is easily occluded in the hydrogen
occluding material. Then, the cooled hydrogen is fed to the
hydrogen storage/delivery means 108, the hydrogen occluding
material. As a result, the hydrogen occlusion rate and the amount
of hydrogen occlusion can be increased. Also, hydrogen can be
withdrawn from the reformer 100 at a lower pressure than the
atmospheric pressure. Thus, the membrane area of the hydrogen
separation membrane of the reformer 100 can be decreased. Moreover,
a required power for the withdrawal of hydrogen can be decreased
markedly in comparison with the power required when a vacuum pump
is used.
[0048] When hydrogen stored in the hydrogen occluding material is
to be delivered, the temperature of the hydrogen storage/delivery
means 108, the hydrogen occluding material, is set at an
appropriate level (e.g., about 80.degree. C.), whereby hydrogen
released at a high-pressure can be obtained. Thus, a hydrogen
compression power necessary when a compressor is used can be cut
down markedly.
[0049] Besides, the sensible heat of the high temperature high
purity hydrogen 103 reformed by the reformer 100 can be utilized
for heating of the raw material gas and steam in the cooler 106.
Thus, the energy efficiency of the entire apparatus can be
increased.
[0050] [Second Embodiment]
[0051] FIG. 2 is a schematic view of an apparatus layout for a
second embodiment of the present invention.
[0052] According to the First Embodiment, the gas mixture 111 of
the raw material gas 101 and steam 102 is fed to the cooler 106 for
heat exchange, in order to utilize the sensible heat of the high
temperature high purity hydrogen 103. In the present embodiment, on
the other hand, combustion air 105 is supplied as shown in FIG.
2.
[0053] As the aforementioned cooler 106, an indirect type heat
exchanger, for example, can be used. In the case of FIG. 2, heat
exchange between the combustion air 105 and high temperature high
purity hydrogen 103 takes place to cool the hydrogen, making it low
temperature high purity hydrogen 107. Heated combustion air 105a
after heating by heat exchange, on the other hand, is fed to a
burner of a reformer 100 (the burner 46 of the reformer illustrated
in FIG. 7).
[0054] In the embodiment shown in FIG. 2, as indicated above, the
combustion air 105 is indirectly heat exchanged with the high
temperature high purity hydrogen 103, and thereby preheated. The
preheated combustion air is fed to the reformer 100, whereby the
energy efficiency of the entire apparatus can be increased.
[0055] [Third Embodiment]
[0056] FIG. 3 shows a third embodiment of the invention. According
to this embodiment, air or cooling water is fed to a cooler 106 as
a low temperature fluid 120a, which is heat exchanged with high
temperature high purity hydrogen 103 to obtain low temperature high
purity hydrogen 107. A low temperature fluid 120b after heat
exchange is discharged out of the system, and utilized as other
heat source.
[0057] [Fourth Embodiment]
[0058] FIG. 4 shows a fourth embodiment of the invention. According
to this embodiment, a hydrogen storage/delivery means is composed
of two members, a hydrogen occluding material 108A and a hydrogen
occluding material 108B. In FIG. 4, the hydrogen occluding material
108A is defined as a hydrogen occlusion side, while a hydrogen
occluding material 108B is defined as a hydrogen delivery side.
[0059] In the hydrogen occluding material 108A on the hydrogen
occlusion side, low temperature high purity hydrogen 107 is flowed,
and cooling water 121a is supplied to cool the entire hydrogen
occluding material 108A. By this measure, hydrogen is efficiently
occluded and stored. Also, low purity hydrogen 110b is
intermittently discharged, or sent to a reformer 100 as purge
hydrogen 110a.
[0060] In the hydrogen occluding material 108B on the hydrogen
delivery side, on the other hand, the low temperature hydrogen 107
is not flowed. However, separately fed high temperature water (50
to 100.degree. C.) 122a heats the entire alloy to release hydrogen
stored in the hydrogen storing alloy, and the hydrogen is delivered
out of the system as high pressure hydrogen 109.
[0061] In the hydrogen occluding material 108A on the hydrogen
supply side, at a time when hydrogen has been occluded up to a set
value for the amount of occlusion in the hydrogen occluding
material, the supply of the low temperature high purity hydrogen
107 and the supply of the cooling water 121a are stopped. Instead,
high temperature water 122b is flowed to liberate high-pressure
hydrogen 109.
[0062] At the same time, in the hydrogen occluding material 108B on
the hydrogen release side, the supply of the high temperature water
122a and the release of the high-pressure hydrogen 109 are stopped.
With cooling water 121b being flowed, low temperature high purity
hydrogen 107 is supplied to have hydrogen occluded.
[0063] By repeating the above procedures alternately, high-pressure
hydrogen 109 is delivered. On this occasion, low purity hydrogen
110c present in the hydrogen occluding material 108B on the
hydrogen delivery side can be discharged intermittently.
[0064] As the high temperature water 122a, 122b fed for hydrogen
release, it is permissible to use waste heat of cooling water 123
that has been fed to a cooler 106 for cooling high temperature high
purity hydrogen 103, in order to utilize the thermal energy within
the apparatus efficiently.
[0065] According to the present embodiment, the waste heat of the
cooling water 123 used for cooling of the high temperature high
purity hydrogen 103 is utilized for heating of the hydrogen
occluding material 108B on the hydrogen delivery side, whereby
effective use of heat can be achieved.
[0066] [Fifth Embodiment]
[0067] FIG. 5 shows a fifth embodiment of the invention. According
to this embodiment, a pressure regulator 130 for low temperature
high purity hydrogen 107 is installed between a cooler 106 and a
hydrogen storage/delivery means 108. As the pressure regulator 130,
an ordinary valve can be used, and a valve involving a decreased
loss in pressure is preferred. High purity hydrogen 131 after
pressure regulation is fed to the hydrogen storage/delivery means
108.
[0068] According to the present embodiment, the pressure regulator
130 is installed between the hydrogen storage/delivery means 108
and the cooler 106. As a result, a buffer zone is formed for
preventing a rapid pressure drop on the hydrogen permeation side of
a hydrogen separation membrane inside are former 100. Consequently,
the durability of the hydrogen separation membrane can be improved.
Moreover, a rapid rise in the temperature of the hydrogen
storage/delivery means 108 associated with its hydrogen occlusion
can also be prevented. Thermal shock to the hydrogen
storage/delivery means 108 can be cushioned. Furthermore, changes
over time in the amount of hydrogen production from the apparatus
for producing hydrogen can be minimized and leveled off. After all,
well balanced hydrogen production can be performed.
EXAMPLES
[0069] The present invention will be described in further detail
with reference to Examples, which are not limitative of the
invention.
Example 1
[0070] A first example of the invention will be explained based on
the apparatus layout shown in FIG. 3. A hydrogen separation type
reformer 100 had the structure shown in FIGS. 7 and 8, as with the
preceding Embodiments. A heat exchanger, a cooler 106, was of a
plate fin type, and used cooling water as a low temperature fluid
120a to cool high temperature high purity hydrogen 103. A hydrogen
occluding material of a hydrogen storage/delivery means 108 was
composed of two members of a hydrogen storing alloy of
LaNi.sub.5.
[0071] Hydrogen was produced under the following concrete
conditions in accordance with the flow shown in FIG. 3.
[0072] (1) Hydrogen Separation Type Reformer (100)
[0073] Main Constitution
[0074] The catalyst of the reformer 100 was an NiO catalyst in
particle form, and the hydrogen separation membrane was made of a
Pd alloy. The membrane area was 0.68 cm.sup.2.
[0075] Operating Conditions
[0076] The reaction temperature of the reformer was 550.degree. C.,
and the reaction pressure was 6 atm. Methane was used as the raw
material gas. The reformer was run, with the flow rate of the raw
material gas being 1.5 m.sup.3 N/h and the steam-carbon ratio being
3.
[0077] (2) Cooler (106)
[0078] The heat exchanger, the cooler 106, was of a plate fin type,
and used cooling water as a cooling medium. The inlet temperature
of cooling water was 25.degree. C., and the outlet temperature of
cooling water was 80.degree. C. The inlet temperature of the high
temperature high purity hydrogen 103 fed to the cooler 106 was
450.degree. C., and the outlet temperature of low temperature high
purity hydrogen 107 after heat exchange was 40.degree. C.
[0079] (3) Hydrogen Storage/Delivery Means (108)
[0080] The hydrogen occluding material, the hydrogen
storage/delivery means 108, was composed of two members of an
LaNi.sub.5 alloy. The inlet temperature of cooling water during
occlusion by the hydrogen storing alloy was 30.degree. C., while
the inlet temperature of cooling water during release of hydrogen
was 80.degree. C. The occluding capacity of the hydrogen storing
alloy was 4 m.sup.3 N/member.
[0081] (4) Amount of Hydrogen Production
[0082] The amount of hydrogen production through the use of the
hydrogen storing alloy as in the present Example was 3.0 m.sup.3
N/h. Whereas the amount of hydrogen production without the use of
the hydrogen storing alloy in the present Example was about a half,
i.e., 1.5 m.sup.3 N/h.
[0083] (5) Power for Hydrogen Supply
[0084] In the present Example, the power required for supply of 3.0
m.sup.3N/h of hydrogen at 6 atm by the hydrogen storing alloy was
about 0.05 kW. Whereas the power required for compression of 3.0
m.sup.3 N/h of hydrogen from 1 atm to 6 atm by a compressor was
about 0.9 kW.
Example 2
[0085] A second example of the invention will be explained based on
the apparatus layout shown in FIG. 3.
[0086] (1) Hydrogen Separation Type Reformer (100)
[0087] The constitution and operating conditions were the same as
in Example 1.
[0088] (2) Cooler (106)
[0089] The same constitution and operating conditions as in Example
1 were adopted, except that the outlet temperature of low
temperature high purity hydrogen 107 in the cooler 106 was
80.degree. C.
[0090] (3) Hydrogen Storing Alloy
[0091] The same constitution and operating conditions as in Example
1 were adopted.
[0092] (4) Amount of Hydrogen Production
[0093] When the high purity hydrogen outlet temperature was
40.degree. C. as in Example 1, the amount of hydrogen production
was 3.0 m.sup.3 N/h. When the high purity hydrogen outlet
temperature was 80.degree. C., on the other hand, the amount of
hydrogen production was 2.0 m.sup.3 N/h.
Example 3
[0094] A third example of the invention will be explained based on
the apparatus layout shown in FIG. 5.
[0095] A hydrogen separation type reformer 100, a cooler 106, and a
hydrogen storage/delivery means 108 had the same constitutions as
in Example 1. A pressure regulator 130 comprises a pressure
regulating valve, and mitigates a rapid pressure fall at the start
of hydrogen occlusion by the hydrogen storage/delivery means 108.
Thus, the pressure regulator 130 curbs a rapid pressure change of
low temperature high purity hydrogen 107 flowing out of the cooler
106.
[0096] Hydrogen was produced under the following concrete
conditions:
[0097] The constitutions and operating conditions of the hydrogen
separation type reformer 100, cooler 106, and hydrogen
storage/delivery means 108 were the same as in Example 1.
[0098] FIG. 6 shows changes in the pressure of low temperature high
purity hydrogen during hydrogen occlusion. Regulation of the
pressure results in the mitigation of a rapid pressure drop
occurring at the start of occlusion.
[0099] The amount of hydrogen production was 3.5 m.sup.3 N/h when
the pressure regulator 130 was installed. Whereas the amount of
hydrogen production was 3.0 m.sup.3 N/h when the pressure regulator
was not used.
[0100] The entire disclosure of Japanese Patent Application
No.11-162416 filed on Jun. 9, 1999, including specification,
claims, drawings and summary, is incorporated herein by reference
in its entirety.
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