U.S. patent application number 11/569920 was filed with the patent office on 2008-03-20 for fuel treating device.
This patent application is currently assigned to EBARA BALLARD CORPORATION. Invention is credited to Shin Inagaki, Kunihiko Murayama, Takashi Suzuki.
Application Number | 20080066438 11/569920 |
Document ID | / |
Family ID | 35462847 |
Filed Date | 2008-03-20 |
United States Patent
Application |
20080066438 |
Kind Code |
A1 |
Inagaki; Shin ; et
al. |
March 20, 2008 |
Fuel Treating Device
Abstract
To provide a fuel processor provided with a heat insulating
shaped body which has high heat resistance and heat insulating
properties, which is good in formability, which is strong against
external impacts, and which can be easily fixed to the fuel
processor 1 or can be filled into a narrow space or the like in the
fuel processor without forming any gap. A fuel processor 1 for
reforming a raw material gas G into a fuel gas J mainly composed of
hydrogen, having a combustion chamber 13 for generating heat for
the reforming, a solid first primary heat insulating material 17
for thermally insulating the combustion chamber 13 from an outside,
and a fabric-like secondary heat insulating material 19 covering
the outside of the first primary heat insulating material 17 for
heat insulation.
Inventors: |
Inagaki; Shin; (Tokyo,
JP) ; Suzuki; Takashi; (Tokyo, JP) ; Murayama;
Kunihiko; (Tokyo, JP) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
EBARA BALLARD CORPORATION
|
Family ID: |
35462847 |
Appl. No.: |
11/569920 |
Filed: |
June 2, 2004 |
PCT Filed: |
June 2, 2004 |
PCT NO: |
PCT/JP04/07625 |
371 Date: |
September 24, 2007 |
Current U.S.
Class: |
55/522 |
Current CPC
Class: |
Y02E 60/50 20130101;
C04B 33/13 20130101; C04B 35/6269 20130101; C04B 2235/9607
20130101; H01M 8/0631 20130101; C01B 3/384 20130101; C04B 35/6316
20130101; B01J 8/0465 20130101; C04B 2235/3445 20130101; C04B
2235/3454 20130101; C04B 38/02 20130101; C04B 2111/0081 20130101;
C04B 2235/77 20130101; B01J 2208/00504 20130101; C04B 2235/3472
20130101; B01J 2208/00495 20130101; C01B 2203/0233 20130101; C01B
2203/0816 20130101; C04B 38/02 20130101; C04B 35/80 20130101 |
Class at
Publication: |
55/522 |
International
Class: |
F23M 5/00 20060101
F23M005/00 |
Claims
1. A fuel processor for reforming a raw material gas into a fuel
gas mainly composed of hydrogen, comprising: a combustion chamber
for generating heat for the reforming; a solid first primary heat
insulating material for thermally insulating the combustion chamber
from an outside; and a fabric-like secondary heat insulating
material covering an outside of the first primary heat insulating
material for heat insulation.
2. The fuel processor as recited in claim 1, wherein an inorganic
foamed body prepared by foaming and curing a mixture containing a
silica-alumina-based fine powder is used as the first primary heat
insulating material, and wherein a secondary heat insulating shaped
body prepared from an inorganic fiber is used as the secondary heat
insulating material.
3. The fuel processor as recited in claim 1, wherein an inorganic
porous body prepared by compression molding of a mixture containing
a silica-based fine powder is used as the first primary heat
insulating material, and wherein a secondary heat insulating shaped
body prepared from an inorganic fiber is used as the secondary heat
insulating material.
4. A fuel processor for reforming a raw material gas into a fuel
gas mainly composed of hydrogen, comprising: a combustion chamber
for generating heat for the reforming; a solid first primary heat
insulating material for thermally insulating the combustion chamber
from an outside; and a fabric-like second primary heat insulating
material for thermally insulating the combustion chamber from a
second section in the fuel processor.
5. A fuel processor for reforming a raw material gas into a fuel
gas mainly composed of hydrogen, comprising: a combustion chamber
for generating heat for the reforming; and a solid first primary
heat insulating material for thermally insulating the combustion
chamber from an outside; wherein an inorganic foamed body prepared
by foaming and curing a mixture containing a silica-alumina-based
fine powder is used as the first primary heat insulating
material.
6. A fuel processor for processing to reform a raw material gas
into a fuel gas mainly composed of hydrogen, comprising: a
combustion chamber for generating heat for the reforming; and a
fabric-like second primary heat insulating material for thermally
insulating the combustion chamber from a second section in the fuel
processor, wherein an inorganic staple fiber felt prepared by
forming a mixture containing an inorganic staple fiber and a heated
expansion material into a felt-like state is used as the second
primary heat insulating material.
Description
TECHNICAL FIELD
[0001] The present invention relates to a fuel processor which
processes a raw material gas to obtain a fuel gas to be supplied to
a fuel cell and, more particularly, to a fuel processor provided
with a heat insulating shaped body which thermally insulates a
combustion section to retain the temperature thereof or thermally
isolates a combustion section.
BACKGROUND ART
[0002] In a fuel processor for producing hydrogen for a solid
polymerelectrolyte fuel cell from a fossil fuel such as natural gas
or kerosene, it is required to maintain and stabilize the
combustion section, catalyst layer, heat exchanging section and so
on of the processor at a high temperature of 100.degree. C. to
800.degree. C. or higher in order to improve the raw material
processing efficiency and to maintain the temperature balance in
the processor properly. To satisfy the requirements, it is
necessary to attach, insert or cover a heat insulating shaped body
having incombustibility, heat resistance and heat-insulating
properties to the combustion section, catalyst layer, heat
exchanging section and so on of the fuel processor in conformity
with their shape and structure. An example to satisfy the
requirements is a fuel processor having a heat insulating shaped
body for heat insulation and temperature retention, which is formed
by compression molding of silica superfine powder such as silica
fumes and is attached to and covering it.
DISCLOSURE OF INVENTION
Problem to be Solved by the Invention
[0003] However, though such a heat insulating shaped body has
satisfactory heat resistance and heat insulating properties, it is
expensive. Also, since it is formed by a method such as compression
molding, it does not have sufficient formability and is difficult
to form into a desired shape. In addition, since the heat
insulating shaped body has low surface hardness and strength, it is
weak against external impacts. Thus it may not be satisfactory in
terms of practicality. Also, such a solid heat insulating material
is difficult to fix and is conventionally fixed with a tape or the
like. In this configuration, a phenomenon occurs in which a gap is
formed between the solid heat insulating materials or between the
container and the fixed heat insulating material because of their
thermal expansion, and heat escapes to the outside. Moreover, when
the solid heat insulating material is filled into a narrow space or
the like, a gap may be formed between the heat insulating material
and the processor to cause deterioration of the heat insulating
performance.
[0004] The present invention has been made in view of the above
technological problems and it is, therefore, an object of the
present invention to provide a fuel processor provided with a heat
insulating shaped body which has high heat resistance and heat
insulating properties, which is good in formability, which is
strong against external impacts, and which can be easily fixed to
the fuel processor or can be filled into a narrow space or the like
in the fuel processor without forming any gap.
Means for Solving the Problem
[0005] In order to achieve the aforementioned object, a fuel
processor according to the present invention as a fuel processor 1
for reforming a raw material gas G into a fuel gas J mainly
composed of hydrogen, has, as shown in FIG. 1 for example, a
combustion chamber 13 for generating heat for the reforming; a
solid first primary heat insulating material 17 for thermally
insulating the combustion chamber 13 from an outside; and a
fabric-like secondary heat insulating material 19 covering an
outside of the first primary heat insulating material 17 for heat
insulation.
[0006] In this configuration, since the fuel processor 1 has the
combustion chamber 13, the first primary heat insulating material
17 and the secondary heat insulating material 19, the first primary
heat insulating material 17 and the secondary heat insulating
material 19 are combined such that the solid first primary heat
insulating material 17 having high heat insulating properties
prevents the combustion heat from leaking from the combustion
chamber 13 to the outside of the processor to maintain the
combustion temperature in the combustion chamber 13 at an
appropriate value, and the fabric-like secondary heat insulating
material 19 covers and thermally insulates the outside of the solid
first primary heat insulating material 17 to reinforce the heat
insulating performance of the first primary heat insulating
material 17 and can protect the first primary heat insulating
material 17 from external impacts. That the secondary heat
insulating material 19 covers the outside of the first primary heat
insulating material 17 includes not only the case in which the
secondary heat insulating material 19 directly covers the outside
of the first primary heat insulating material 17 but also the case
in which there is an intermediate member interposed between the
secondary heat insulating material 19 and the first primary heat
insulating material 17 and the secondary heat insulating material
19 covers the outside of the intermediate member.
[0007] In the fuel processor 1 according to the present invention
as recited above, as shown in FIG. 1 for example, an inorganic
foamed body 37A prepared by foaming and curing a mixture containing
a silica-alumina-based fine powder may be used as the first primary
heat insulating material 17, and a secondary heat insulating shaped
body 39 prepared from an inorganic fiber may be used as the
secondary heat insulating material 19.
[0008] In this configuration, since the inorganic foamed body 37A
and the secondary heat insulating shaped body 39 are used in the
fuel processor 1, the inorganic foamed body 37A and the secondary
heat insulating shaped body 39 are combined such that the inorganic
foamed body 37A having excellent heat resistance and good heat
insulating properties at high temperatures and being able to be
formed as a unitary body prevents the combustion heat from leaking
from the combustion chamber 13 to the outside of the processor to
maintain the combustion temperature in the combustion chamber 13 at
an appropriate value, and the secondary heat insulating shaped body
39 having good installability and strength thermally insulates the
outside of the inorganic foamed body 37A of insufficient strength
to reinforce the heat insulating performance of the inorganic
foamed body 37A and to protect the inorganic foamed body 37A from
external impacts.
[0009] In the fuel processor 1 according to the present invention
as recited above, as shown in FIG. 1 for example, an inorganic
porous body 37B prepared by compression molding of a mixture
containing a silica-based fine powder may be used as the first
primary heat insulating material 17, and a secondary heat
insulating shaped body 39 prepared from an inorganic fiber may be
used as the secondary heat insulating material 19.
[0010] In this configuration, since the inorganic porous body 37B
and the secondary heat insulating shaped body 39 are used in the
fuel processor 1, the inorganic porous body 37B and the secondary
heat insulating shaped body 39 are combined such that the inorganic
porous body 37B having excellent heat resistance and good heat
insulating properties at high temperatures prevents the combustion
heat from leaking from the combustion chamber 13 to the outside of
the processor to maintain the combustion temperature in the
combustion chamber 13 at an appropriate value, and the secondary
heat insulating material 19 having good installability and strength
thermally insulates the outside of the inorganic porous body 37B,
which is brittle and difficult to fix, to make the inorganic porous
body 37B strong against external impacts and can fix the inorganic
porous body 37B to the fuel processor 1 reliably.
[0011] In order to achieve the aforementioned object, another fuel
processor 1 according to the present invention as a fuel processor
1 for reforming a raw material gas G into a fuel gas J mainly
composed of hydrogen has, as shown in FIG. 1 for example, a
combustion chamber 13 for generating heat for the reforming; a
solid first primary heat insulating material 17 for thermally
insulating the combustion chamber 13 from an outside; and a
fabric-like second primary heat insulating material 18 for
thermally insulating the combustion chamber 13 from a second
section in the fuel processor 1.
[0012] In this configuration, since the fuel processor 1 has the
combustion chamber 13, the first primary heat insulating material
17, and the second primary heat insulating material 18, the first
primary heat insulating material 17 and the second primary heat
insulating material 18 are combined such that the first primary
heat insulating material 17 prevents the combustion heat from
leaking from the combustion chamber 13 to the outside of the
processor to maintain the combustion temperature in the combustion
chamber 13 at an appropriate value, and the second primary heat
insulating material 18 thermally insulates the combustion chamber
13 from a second section in the fuel processor 1 to maintain the
combustion temperature in the combustion chamber 13 at an
appropriate value and to maintain the temperature of the second
section at a low temperature suitable therefor. The solid first
primary heat insulating material 17 having high heat insulating
performance and heat resistance performance is provided to
thermally insulate the combustion chamber 13 from the outside and
the second primary heat insulating material 18 with flexibility is
inserted into a space formed between the combustion chamber 13 and
the second section to thermally insulate the combustion chamber 13
from the second section, that is, the first primary heat insulating
material 17 and the second primary heat insulating material 18 are
used appropriately depending on the purposes to achieve efficient
heat insulation. The second section in the fuel processor 1 means
the section which is required to have a temperature lower than that
in the combustion chamber 13 in the fuel processor 1.
[0013] In order to achieve the aforementioned object, another fuel
processor 1 according to the present invention as a fuel processor
1 for reforming a raw material gas G into a fuel gas J mainly
composed of hydrogen has, as shown in FIG. 1 for example, a
combustion chamber 13 for generating heat for the reforming; and a
solid first primary heat insulating material 17 for thermally
insulating the combustion chamber 13 from an outside; wherein an
inorganic foamed body 37A prepared by foaming and curing a mixture
containing a silica-alumina-based fine powder is used as the first
primary heat insulating material 17.
[0014] In this configuration, since the fuel processor 1 has the
combustion chamber 13 and the first primary heat insulating
material 17 and since the inorganic foamed body 37A is used as the
first primary heat insulating material 17, the inorganic foamed
body 37A having excellent heat resistance and good heat insulating
properties at high temperatures and being able to be formed as a
unitary body can prevent the combustion heat from leaking from the
combustion chamber 13 to the outside of the processor to maintain
the combustion temperature in the combustion chamber 13 at an
appropriate value.
[0015] In order to achieve the aforementioned object, another fuel
processor 1 according to the present invention as a fuel processor
for processing to reform a raw material gas G into a fuel gas J
mainly composed of hydrogen, as shown in FIG. 1 for example, has a
combustion chamber 13 for generating heat for the reforming; and a
fabric-like second primary heat insulating material 18 for
thermally insulating the combustion chamber 13 from a second
section in the fuel processor 1, wherein an inorganic staple fiber
felt 38A prepared by forming a mixture containing an inorganic
staple fiber and a heated expansion material into a felt-like state
is used as the second primary heat insulating material 18.
[0016] In this configuration, since the fuel processor 1 has the
combustion chamber 13 and the second primary heat insulating
material 18 and since the inorganic staple fiber felt 38A having
excellent heat resistance and good heat insulating properties at
high temperatures is used as the second primary heat insulating
material 18, the combustion chamber 13 can be thermally insulated
from the second section in the fuel processor 1 to maintain the
combustion temperature in the combustion chamber 13 at an
appropriate value and to maintain the temperature of the second
section at a low temperature suitable therefor. Since the inorganic
staple fiber felt 38A, which has flexibility, is excellent in
formability, and turns into powder and foams and expands under a
high temperature condition, is inserted into a space formed between
the combustion chamber 13 and the second section for the heat
insulation between the combustion chamber 13 and the second
section, efficient heat insulation can be achieved.
Effect of the Invention
[0017] As described above, according to the present invention, the
fuel processor has the combustion chamber, the first primary heat
insulating material, and the secondary heat insulating material.
Therefore, the solid first primary heat insulating material having
high heat insulating properties can reduce the leakage of the
combustion heat from the combustion chamber to the outside of the
processor to maintain the combustion temperature in the combustion
chamber at an appropriate value, and the fabric-like secondary heat
insulating material covering the outside of the solid first primary
heat insulating material for heat insulation can reinforce the heat
insulating performance of the first primary heat insulating
material and protect the first primary heat insulating material
from external impacts.
BEST MODE FOR CARRYING OUT THE INVENTION
[0018] Description is hereinafter made of an embodiment of the
present invention with reference to the drawing.
[0019] FIG. 1 is a cross-sectional view illustrating the general
configuration of a fuel reformer 1 as a fuel processor according to
the embodiment of the present invention. As shown in the drawing,
the fuel reformer 1 having a generally circular columnar shape is
installed in an upright position and has a combustion material
introducing section 11; a burner 12 (the combustion flame is shown
by dot-and-dash lines); a combustion chamber 13; a reforming
catalyst layer 14; a shift catalyst layer 15, a selective oxidation
catalyst layer 16; a first primary heat insulating section 17; a
second primary heat insulating section 18; a secondary heat
insulating section 19; a partition 41; a partition 42; a partition
43; a partition 44; a partition 45; a partition 46; and a partition
47. These elements except the combustion material introducing
section 11 and the secondary heat insulating section 19, are housed
in the secondary heat insulating section 19 having a circular
cylindrical shape.
[0020] The combustion material introducing section 11 is located at
the center of an upper part of the fuel reformer 1, and has a raw
material introduction port 31. Combustion materials (combustion gas
D and combustion air E) are introduced through the raw material
introduction port 31. The burner 12, which is connected to an
opening 3 formed at the center of an upper part of the fuel
reformer 1 and immediately below the combustion material
introducing section 11 and suspended along the central axis of the
fuel reformer 1, burns the combustion gas D. The combustion chamber
13 has a circular cylindrical combustion cylinder 13A as a
peripheral wall surrounding it and houses the burner 12. In the
combustion chamber 13, the combustion gas D is burned by the burner
12 to generate heat for use in reforming raw material gas G. The
reforming catalyst layer 14 has an annular shape and is located
outside the combustion cylinder 13A (radially outside of the fuel
reformer 1). The reforming catalyst layer 14 is housed between the
partition 41 and the partition 42 with its inside and outside in
direct contact with the partition 41 and the partition 42,
respectively.
[0021] The first primary heat insulating section 17 is a solid
first primary heat insulating shaped body 37 prepared by forming a
first primary heat insulating material. Since the first primary
heat insulating shaped body 37 is solid, it is brittle but has high
heat insulating and heat resistance performances. Since the first
primary heat insulating shaped body 37 is solid, it does not have
sufficient formability and thus is not suitable to fill a narrow
space to be filled. Therefore, the first primary heat insulating
shaped body 37 is filled in a large space to be filled in a lower
part of the fuel reformer 1 as shown in the drawing. The first
primary heat insulating shaped body 37 is classified, based on the
composition of the first primary heat insulating material as
described later, into (1) an inorganic foamed body 37A, (2) an
inorganic porous body 37B or (3) an inorganic combined body 37C in
which the first heat insulating material for the inorganic foamed
body 37A and the first heat insulating material for the inorganic
porous body 37B are combined like blocks.
[0022] The first primary heat insulating section 17 has a circular
columnar shape with a circular columnar recess 20 at an upper part
thereof, and is disposed in a lower part of the fuel reformer 1 in
contact with the bottom and a lower part of the inner wall of a
secondary heat insulating shaped body 39, which is described later.
In the recess 20, a lower part of the combustion chamber 13 and a
lower part of the reforming catalyst layer 14 are housed. The
recess 20 is disposed in contact with an outer peripheral surface
43A of the partition 43 or with a gap of about 1 mm between it and
the outer peripheral surface 43A. That is, the secondary heat
insulating shaped body 39 covers and thermally insulates the
outside of the first primary heat insulating section 17.
[0023] The second primary heat insulating section 18 is a
fabric-like second primary heat insulating shaped body 38 prepared
by forming a second primary heat insulating material which is
different from the first primary heat insulating material for the
first primary heat insulating shaped body 37. Preparing a heat
insulating shaped body to be fabric-like means that the heat
insulating shaped body has a fiber structure, can be freely
deformed, has a length in the thickness direction which is much
smaller than the lengths in the longitudinal and lateral
directions, and its components are so stable that they are not
changed in nature and scattered when the heat insulating shaped
body is deformed. Since the second primary heat insulating shaped
body 38 is fabric-like, it has flexibility and can be easily filled
into a space to be filled with a narrow filling port and a large
aspect ratio (ratio between the insertion length and the width of
the filling port). The second primary heat insulating shaped body
38 is an inorganic staple fiber felt 38A formed in an annular
shape, and disposed outside the reforming catalyst layer 14
(radially outside of the fuel reformer 1) and above the first
primary heat insulating section 17. The inorganic staple fiber felt
38A is housed between the partition 43 and the partition 44 with
its inside and outside in direct contact with the partition 43 and
the partition 44, respectively.
[0024] The shift catalyst layer 15 has an annular shape and is
disposed outside the second primary heat insulating section 18
(radially outside of the fuel reformer 1). The shift catalyst layer
15 is housed between the partition 44 and the partition 45 with its
inside and outside in direct contact with the partition 44 and the
partition 45, respectively. The selective oxidation catalyst layer
16 has an annular shape and is located outside the shift catalyst
layer 15 (radially outside of the fuel reformer 1). The selective
oxidation catalyst layer 16 is housed between the partition 46 and
a vertical portion 47A of the partition 47. The secondary heat
insulating shaped body 39 is disposed outside the selective
oxidation catalyst layer 16. The secondary heat insulating shaped
body 39 is disposed in contact with the outside of the vertical
portion 47A of the partition 47. The partitions 41 to 47 are each
preferably made of a stainless steel plate. The secondary heat
insulating section 19 is the secondary heat insulating shaped body
39 made of a staple fiber heat insulating material as a secondary
heat insulating material and having a generally circular
cylindrical container structure and houses the elements of the fuel
reformer 1, such as the burner 12 as described before, but the
combustion material introducing section 11.
[0025] The fuel reformer 1 further includes a combustion flue gas
passage 21, a raw material gas passage 22, and a reformate passage
23. The secondary heat insulating shaped body 39 having a container
structure has a side wall with halls through which a combustion
flue gas outlet 32, a raw material gas inlet 33, a reformate outlet
34, and a selective oxidation air inlet 35 each having a pipe-like
shape extend.
[0026] The combustion flue gas passage 21 has an annular shape part
formed between the combustion cylinder 13A and the partition 41 and
a thin disk shape part formed in an upper part of the fuel reformer
1 and immediately below a horizontal portion 47B of the partition
47 in contact with a ceiling portion 36 of the secondary heat
insulating section 19. Combustion flue gas F produced upon
combustion of the raw material gas G by the burner 12 flows through
the combustion flue gas passage 21 and is discharged to the outside
of the fuel reformer 1 from the combustion flue gas outlet 32. The
combustion flue gas F heats the reforming catalyst layer 14 while
flowing through the combustion flue gas passage 21, and the
reforming catalyst layer 14 is heated to a temperature in the range
of 300.degree. C. to 800.degree. C. Also, a part of the raw
material gas passage 22 extends immediately below the combustion
flue gas passage 21 with a disk-like shape as described later, and
the combustion flue gas F preheats the raw material gas G before
the raw material gas G contacts the reforming catalyst layer
14.
[0027] The raw material gas passage 22 is formed in an upper part
of the fuel reformer 1 and immediately below the combustion flue
gas passage 21. The raw material gas passage 22 has in its
intermediate portion a passage 22A having an annular shape and a
passage 22B also having an annular shape. In the passage 22A, the
raw material gas G flows downward between the selective oxidation
catalyst layer 16 and the shift catalyst layer 15, and flows
through a heat exchanging section 25 in which the raw material gas
G exchanges heat with the selective oxidation catalyst layer 16 via
the partition 46, whereby the raw material gas G is preheated by
the selective oxidation catalyst layer 16. In the passage 22B, the
raw material gas G reverses its direction of flow, further flows
upward between the selective oxidation catalyst layer 16 and the
shift catalyst layer 15, and flows through a heat exchanging
section 26 in which the raw material gas G exchanges heat with the
shift catalyst layer 15 via the partition 45, whereby the raw
material gas G is preheated by the shift catalyst layer 15.
[0028] The raw material gas G, to which water H has been added,
enters the raw material gas passage 22 from the raw material gas
inlet 33, and is supplied to the reforming catalyst layer 14
through the raw material gas passage 22. The reformate passage 23
includes a passage 23A formed in an annular shape between the first
primary heat insulating section 17 and the reforming catalyst layer
14, a passage 23B formed above the shift catalyst layer 15, a
passage 23C formed below the shift catalyst layer 15 and the
selective oxidation catalyst layer 16, and a passage 23D formed
above the selective oxidation catalyst layer 16. The shift catalyst
layer 15 and the selective oxidation catalyst layer 16 each also
form a part of the reformate passage 23.
[0029] The raw material gas G and the water H are preheated to
100.degree. C. to 500.degree. C. while flowing through the heat
exchanging section 25 and the heat exchanging section 26 as the raw
material gas passage 22 between the selective oxidation catalyst
layer 16 and the shift catalyst layer 15. The raw material gas G is
reformed into a reformate (reformed gas) M mainly composed of
H.sub.2 and CO through a reforming reaction in the reforming
catalyst layer 14. The reformate M is fed from the reforming
catalyst layer 14 to the shift catalyst layer 15 through the
passages 23A and 23B. The CO in the reformate M is shifted to
H.sub.2 and CO.sub.2 through a shift converter reaction in the
shift catalyst layer 15, whereby the amount of CO in the reformate
M decreases. The reformate M is fed from the shift catalyst layer
15 to the selective oxidation catalyst layer 16 through the passage
23C. The CO in the reformate M is oxidized through a selective
oxidation reaction with air K fed from the selective oxidation air
inlet 35 in the selective oxidation catalyst layer 16 and removed
therefrom, whereby the reformate M is turned into fuel gas J mainly
composed of H.sub.2. To be mainly composed of H.sub.2 means to
contain a sufficient amount of hydrogen necessary to generate
electric power through an electrochemical reaction with an
oxidizing material in a fuel cell. In general, it means to contain
50% or more by volume, preferably approximately 80% by volume, of
hydrogen. The reformate M, from which CO has been removed, flows
through the passage 23D and is discharged to the outside of the
fuel reformer 1 through the reformate outlet 34. The reformate M is
then supplied to a solid polymer electrolyte fuel cell (not shown)
as fuel gas J mainly composed of H.sub.2 and used for fuel cell
power generation.
[0030] The first primary heat insulating section 17 prevents heat
from the high-temperature section, that is, (1) the combustion
chamber 13, (2) the reforming catalyst layer 14, and (3) a heat
exchanging section 24 in which the combustion flue gas F and the
reforming catalyst layer 14 exchange heat via the partition 41,
from escaping to the outside (the outside of the fuel reformer 1,
the same applies hereinafter) (that is referred to as first primary
heat insulation). The second primary heat insulating section 18
thermally insulates the radial outer periphery of the
high-temperature section, and isolates the high-temperature section
with a generally circular columnar shape from a low-temperature
section with an annular shape surrounding the high-temperature
section, that is, (1) the shift catalyst layer 15, (2) the
selective oxidation catalyst layer 16, and (3) the heat exchanging
sections 25 and 26 (that is referred to as second primary heat
insulation) The low-temperature section is a second section in the
fuel processor of the present invention. Here, the low-temperature
section has a temperature which is relatively lower than that of
the high-temperature section and higher than that of the ambient
air. The secondary heat insulating section 19 is formed like it
makes the circular cylindrical outer wall of the fuel reformer 1,
and covers and thermally insulates the outside of the first primary
heat insulating shaped body 37 in order to prevent heat from
escaping from the outer surface of the fuel reformer 1 to the
outside (secondary heat insulation).
[0031] In the present invention, the first primary heat insulation
means to prevent heat from escaping from the high-temperature
section including the combustion chamber 13 and so on to the
outside as described before, and the second primary heat insulation
means to insulate and thermally isolate the high-temperature
section including the combustion chamber 13 and so on from the
low-temperature section including the shift catalyst layer 15 and
so on and surrounding the high-temperature section.
[0032] Next, the heat insulating materials for the first primary
heat insulating section 17, the second primary heat insulating
section 18, and the secondary heat insulating section 19 are
described in greater detail.
[0033] The first primary heat insulating shaped body 37 forming the
first primary heat insulating section 17 is formed by the first
primary heat insulating material. The first primary heat insulating
shaped body 37 is attached to and covers the inside of the fuel
reformer 1 and can insulate the high-temperature section (600 to
800.degree. C.) from the outside. The first primary heat insulating
shaped body 37 is formed in a three-dimensional shape and in a
solid state.
[0034] The second primary heat insulating shaped body 38 forming
the second primary heat insulating section 18 is formed by the
second primary heat insulating material. The second primary heat
insulating shaped body 38 is formed in an annular shape and in a
fabric-like state, is inserted and attached between the
high-temperature section and the low-temperature section, and can
insulate and thermally isolate the high-temperature section from
the low-temperature section. By using the first primary heat
insulating shaped body 37 and the second primary heat insulating
shaped body 38 the temperature of the high-temperature section can
be maintained and by insulating and thermally isolating the
high-temperature section from the low-temperature section, the fuel
reformer 1 can process the raw material gas G efficiently and
produce the fuel gas J efficiently.
[0035] In addition, the secondary heat insulating shaped body 39 is
formed by the second heat insulating material. The secondary heat
insulating shaped body 39, which is formed in a circular
cylindrical shape, is attached to and covers the outer peripheries
(side, top and bottom surfaces) of the fuel reformer 1 provided
with the primary heat insulation and can decrease the surface
temperature of the fuel reformer 1 to a temperature low enough not
to cause burn injury even when touching the fuel reformer 1.
[0036] As the first primary heat insulating shaped body 37, (1) an
inorganic foamed body 37A mainly composed of a silica-alumina-based
fine powder, (2) an inorganic porous body 37B mainly composed of a
silica superfine powder, or (3) an inorganic combined body 37C in
which the heat insulating material for the inorganic foamed body
37A and the heat insulating material for the inorganic porous body
37B are combined like blocks can be used.
[0037] As the second primary heat insulating shaped body 38, an
inorganic staple fiber felt 38A mainly composed of rock wool,
ceramic wool or mixed wool obtained by mixing them can be used.
[0038] The secondary heat insulating shaped body 39 is prepared by
forming rock wool as an inorganic staple fiber or glass wool as an
inorganic staple fiber into a circular cylindrical shape, providing
an outer skin material 40 such as ALGC (aluminum glass cross) on
the outer peripheries (side, top and bottom surfaces) thereof, and
cutting holes for the pipes for the combustion flue gas F, the raw
material gas G, the fuel gas J, the selective oxidation air K
(piping nozzles respectively connected to the raw material
introduction port 31, the combustion flue gas outlet 32, the raw
material gas inlet 33, the reformate outlet 34 and the selective
oxidation air inlet 35).
[0039] The primary heat insulating materials (the first primary
heat insulating material and the second primary heat insulating
material) are made of inorganic materials which are inferior in
mechanical strength but excellent in heat resistance and can
perform a high temperature insulation at 1000.degree. C. or higher.
Therefore, even when the high-temperature section inside has a
temperature of 600 to 800.degree. C., the temperature of the
external surfaces of the fuel reformer 1 provided with the primary
heat insulation (first primary heat insulation and second primary
heat insulation) can be decreased to 100.degree. C. to 200.degree.
C. The second primary heat insulating material for use in this
embodiment of the present invention is superior in heat resistance
but inferior in mechanical strength since the heated expansion
material turns into powder and becomes brittle when heated as
described later. Also, the secondary heat insulating material,
which is made of a material which is slightly inferior in heat
resistance to the primary heat insulating material but is
inexpensive and has practical strength, can be easily attached to
and cover the inside of the fuel reformer 1, and is intended for
protection of the first primary heat insulating shaped body 37 as
well as for heat insulation and temperature retention in a
temperature range of 300.degree. C. or lower. As described above,
the production efficiency of the fuel reformer 1 can be improved by
the primary heat insulation and secondary heat insulation, and it
is, therefore, possible to provide the fuel reformer 1 provided
with heat insulating shaped bodies having high practicality.
[0040] The first primary heat insulating shaped body 37 may be an
inorganic foamed body 37A prepared by foaming a mixture of a
silica-alumina-based fine powder, a heat reflecting material, a
heat resistance fiber, a foam stabilizer and a curing agent to a
density of approximately 500 kg/m.sup.3 or less and curing the
foamed mixture to be formed.
[0041] The first primary heat insulating shaped body 37 may be an
inorganic porous body 37B prepared by compression molding of a
mixture of a silica-based fine powder, a heat resistance fiber and
a heat reflecting material to a density of approximately 500
kg/m.sup.3 or less.
[0042] The second primary heat insulating shaped body 38 may be an
inorganic staple fiber felt 38A prepared by shaping a mixture of an
inorganic staple fiber and a heated expansion material into a
felt-like state. The inorganic staple fiber is preferably selected
from the group consisting of rock wool, ceramic wool, and a mixed
fiber of rock wool and ceramic wool. An inorganic staple fiber
having been subjected to shot removing treatment may be used. The
inorganic staple fiber felt 38A may be prepared by shaping a
mixture of an inorganic fiber selected from the group consisting of
rock wool, ceramic wool, and a mixed fiber of rock wool and ceramic
wool; a sintering material; a binding agent; and a heated expansion
material into a felt-like state.
[0043] The secondary heat insulating shaped body 39 is preferably
prepared by forming and curing an inorganic staple fiber to which a
binding agent has been applied into a circular cylindrical shape
and attaching a nonflammable fabric around the outer periphery of
the circular cylindrical shaped body. The inorganic staple fiber is
preferably a rock wool staple fiber or a glass wool staple fiber.
As the binding agent, a compound selected from the group consisting
of a water-soluble phenol resin, a melamine resin, and colloidal
silica is preferably used.
[0044] The first primary heat insulating shaped body 37 for the
first primary heat insulation, the second primary heat insulating
shaped body 38 for the second primary heat insulation, and the
secondary heat insulating shaped body 39 for the secondary heat
insulation are described below in detail.
[0045] The heat insulating material for the first primary heat
insulating section 17 is composed of the first primary heat
insulating shaped body 37. As the first primary heat insulating
shaped body 37, the inorganic foamed body 37A is formed by mixing
and stirring a mixture of 100 parts by weight of a matrix material
containing a silica-alumina-based fine powder as a primary
component; a heat reflecting material; a heat resistance fiber; a
fine powder weight reduction material; and an organic binding
agent; 50 to 100 parts by weight of a curing agent; 5 to 15 parts
by weight of a foaming agent; and 0.1 to 0.2 parts by weight of a
foam stabilizer, and injecting the resulting mixture into a mold so
that it can be formed into a predetermined shape as shown in the
drawing.
[0046] The silica-alumina-based fine powder is composed of
metakaolin, bauxite, amorphous silica, fly ash, cement and so on.
As the heat reflecting material, a titanium oxide fine powder is
preferably used. As the heat resistance fiber, a glass chopped
fiber is preferably used since it can also serve as a dimensional
stabilizer and a reinforcing material. As a particulate
weight-reducing material, pearlite, glass balloon, or volcanic ash
balloon is preferably used. As an organic binding agent intended to
improve the strength of the inorganic foamed body 37A, a
water-soluble modified acrylic resin, poval (polyvinyl alcohol) or
the like is used. As the curing agent, a sodium- or potassium-based
alkali metal silicate is preferably used. An aluminum powder or
hydrogen peroxide aqueous solution is preferably used as the
foaming agent, and casein, a silicone resin, castor oil
ethylene-propylene oxide or the like is preferably used as the foam
stabilizer.
[0047] After the injection, the mixture is allowed to foam and cure
at a temperature of 50 to 70.degree. C. for 30 minutes to 2 hours,
and is matured and dried at a temperature around 100.degree. C. for
approximately 2 hours. The resulting product is then treated at a
temperature of 500 to 600.degree. C. for a short period of time in
order to reinforce heat resistance and dimensional stability to it,
whereby the inorganic foamed body 37A can be obtained. The density
and thermal conductivity of the inorganic foamed body 37A prepared
as described above depend on the type of the foam stabilizer, the
amount of the foaming agent, the amount of the weight-reducing
material, and so on. From the viewpoint of practicality, the
density is preferably in the range of 200 to 500 kg/m.sup.3, more
preferably in the range of 200 to 300 kg/m.sup.3. Then, a
performance of a thermal conductivity of 0.030 to 0.060 W/mK as an
indicator of heat insulating properties can be obtained. Also,
since the heat resistance temperature of the inorganic foamed body
37A is as high as approximately 1000.degree. C., it is a heat
insulating material for the primary heat insulation which satisfies
the requirements suitable for heat insulation of the aforementioned
high-temperature section (600 to 800.degree. C.).
[0048] A first primary heat insulating shaped body 37 of a second
embodiment described below may be used for the first primary heat
insulating section 17. The primary heat insulating shaped body 37
of the second embodiment can be an inorganic porous body 37B
prepared by compression molding of a mixture containing a
silica-based fine powder as a primary component, a heat reflecting
material and a heat resistance fiber. As the silica-based fine
powder, silica fume, which is a silica superfine powder, or the
like is used. As the heat reflecting material, fine powder titanium
oxide or zirconium oxide is preferably used. The heat resistance
fiber also functions as a reinforcing material, and a glass chopped
fiber is preferably used for it. This inorganic porous body 37B is
preferably used at a low density since its materials are expensive.
From the viewpoint of shape-retaining property and economic
efficiency, the inorganic porous body 37B has a density preferably
in the range of 200 to 500 kg/m.sup.3, more preferably in the range
of 200 to 300 kg/m.sup.3. When the density is in the above range, a
performance of a thermal conductivity of 0.020 to 0.030 W/mK can be
obtained. Also, the heat resistance temperature of the inorganic
porous body 37B is as high as approximately 1000.degree. C.
[0049] Although the inorganic porous body 37B is expensive as a
material, it can provide excellent high-temperature heat insulation
effect and satisfies the requirements for primary heat
insulation.
[0050] The inorganic foamed body 37A or the inorganic porous body
37B is light in weight and excellent in heat resistance and heat
insulating properties, and have sufficient performance for heat
insulation and temperature retention of the combustion chamber 13
and so on of the fuel reformer 1 having a high temperature of 600
to 800.degree. C. However, the first primary heat insulating shaped
body 37 as the inorganic foamed body 37A or the inorganic porous
body 37B has low strength and low surface hardness and is not
sufficient in machinability. In order to overcome the problems, a
combination with the secondary heat insulating shaped body 39 for
thermally insulating and covering the first primary heat insulating
shaped body 37 is preferred from the viewpoint of economic
efficiency.
[0051] In the fuel reformer 1 according to this embodiment, a
felt-like second primary heat insulating shaped body which can be
easily inserted or attached into a narrow, circular cylindrical gap
can be used for heat insulation and temperature retention as the
second primary heat insulation for separating the temperature
regions in the fuel reformer 1 (separating the high-temperature
section and the low-temperature section).
[0052] The heat insulating material for the second primary heat
insulating section 18 is composed of a felt-like second primary
heat insulating shaped body 38, which is easy to insert or attach.
The second primary heat insulating shaped body 38 of this
embodiment can be an inorganic staple fiber felt 38A which is
prepared by forming a slurry obtained by dispersing in water a
mixture of 100 parts by weight of an inorganic staple fiber; 5 to
40 parts by weight of a heated expansive inorganic powder; 5 to 15
parts by weight of a sinterable inorganic powder; and 10 parts by
weight or less, preferably 7 parts by weight or less in view of
incombustibility, of a binding agent containing a binding aid
material into a felt-like state with a sheet making machine like a
circular net type or a long net type papermaking machine, and
drying and curing the felt-like product.
[0053] The inorganic staple fiber for the inorganic staple fiber
felt 38A is rock wool, ceramic wool, or a mixture thereof. Rock
wool and ceramic wool are obtained by melting a mixture of raw
material mineral substances (35 to 55 wt % of SiO.sub.2; 10 to 20
wt % of Al.sub.2O.sub.3; 5 to 40 wt % of MgO; 5 to 40 wt % of CaO;
0 to 10 wt % of FeO; and 0 to 10 wt % of minor components such as
Cr.sub.2O.sub.3, Na.sub.2O, K.sub.2O, TiO.sub.2 and MnO for rock
wool, 47 to 52 wt % of SiO.sub.2; 47 to 52 wt % of Al.sub.2O.sub.3;
0 to 10 wt % in total of minor components such as CaO, MgO,
TiO.sub.2 and ZrO.sub.2 for ceramic wool) in a cupola furnace or an
electric furnace at a temperature of 1400 to 1600.degree. C. and
fiberizing the molten mixture by a blowing method or a spinning
method using a high-speed spinner. Since such an inorganic staple
fiber contains approximately 30 wt % of unfiberized particles
called "shot", it is used after removing shot therefrom.
[0054] As the heated expansive inorganic powder (heated expansion
material), an unburned vermiculite powder or expansive graphite is
preferably used. As the sinterable inorganic powder, a sinterable
inorganic powder such as pyroborate, sepiolite, attapulgite,
low-melting-point glass frit, potassium titanate whisker is
preferably used. As the organic binding agent and inorganic binding
agent, an acrylic resin, modified acrylic resin, vinyl acetate
resin, phenol resin, colloidal silica or the like is used. As the
binding aid material, polyethylene pulp, polyethylene-polypropylene
composite fiber, nylon fiber or the like is preferably used.
[0055] This inorganic staple fiber felt 38A properly has a
thickness of 2 to 5 mm and a basis weight of 300 to 2000 g/m.sup.2
although they depend on the shape in which it is inserted or
attached. Since the inorganic staple fiber felt 38A after
heat-foaming of felt has a thermal conductivity in the range of
0.030 to 0.050 W/mK and a heat resistance as high as 700 to
1000.degree. C., it can be used as the insertion-type second
primary heat insulating shaped body 38 for heat insulation and
temperature retention to isolate the high-temperature section from
the low-temperature section in the fuel reformer 1.
[0056] The heat insulating material for the secondary heat
insulating section 19 is composed of the secondary heat insulating
shaped body 39. One basic form of the secondary heat insulating
shaped body prepared by forming rock wool or glass wool staple
fiber as an inorganic staple fiber into a circular cylindrical
shape can be produced in a production facility for a heat
insulating cylinder made of aforementioned rock wool or glass wool
composed of 60 to 72 wt % of SiO.sub.2; 1 to 5 wt % of
Al.sub.2O.sub.3; 0 to 5 wt % of MgO; 6 to 11 wt % of CaO; 0 to 7 wt
% of B.sub.2O.sub.3; and 14 to 19 wt % of R.sub.2O
(Na.sub.2O+K.sub.2O). To prepare the secondary heat insulating
shaped body 39, the before-mentioned ingredients of rock wool or
glass wool are melted in a cupola furnace or electric furnace and
fiberizing the molten mixture with a high-speed spinner or the
like. In this process, a mat having fibers on which a water-soluble
binder solution of a water-soluble phenol resin, a water-soluble
melamine resin and colloidal silica, which may be mixed with a
wax-based water repellent agent and/or a silane coupling agent as
needed, has been sprayed and coated is wound around a circular
cylindrical core pipe and thermally cured for 5 to 20 minutes at a
temperature of 150 to 250.degree. C. When the mat is cut and the
core is removed, a mating-halves type heat insulating material with
a circular cylindrical shape is obtained. The circular cylindrical
heat insulating material has a density of 80 to 150 kg/M.sup.3, a
thermal conductivity of 0.030 to 0.050 W/mK, and heat resistance
suitable for a temperature range of 300 to 700.degree. C. Also,
aforementioned circular cylindrical heat insulating material is
fabricated into the secondary heat insulating shaped body 39 by
bonding an outer skin material 40 of ALGC (aluminum glass cross) as
a nonflammable fabric or ALK (aluminum craft paper) as a
nonflammable fabric thereto and cutting holes for piping
therethrough. The secondary heat insulating shaped body 39 is
attached to cover the fuel reformer 1 provided with the primary
heat insulation in a circular cylindrical shape.
[0057] As described above, even when the internal temperature of
the fuel reformer 1 according to the present invention for
producing the fuel gas J, which the first primary heat insulating
shaped body 37, the second primary heat insulating shaped body 38,
the secondary heat insulating shaped body 39 is inserted into, is
attached to and covers, is 600 to 800.degree. C., the outer surface
temperature of the fuel reformer 1 can be decreased to 30 to
50.degree. C. That means they are excellent in heat insulating and
temperature retaining properties and light in weight, and have high
maintainability. Also, workability in inserting, attaching and
providing the first primary heat insulating shaped body 37, the
second primary heat insulating shaped body 38, and the secondary
heat insulating shaped body 39 is good and both economic efficiency
and practicality are satisfied. They can flexibly follow the
expansion and contraction of the container due to repetition of
start and stop of the operation and exhibits good heat insulating
properties. Therefore, the technological problems to be solved by
the present invention can be solved.
EXAMPLES
[0058] The first primary heat insulating shaped body 37 formed by
the first primary heat insulating material, the second primary heat
insulation shaped body 38 formed by the second primary heat
insulating material, and the secondary heat insulating shaped body
39 formed by the secondary heat insulating material for the fuel
processor of the present invention are described with examples.
[0059] An example of the inorganic foamed body 37A (first primary
heat insulating shaped body 37) is described (Example 1). 220 Grams
of a fine powder mixture, with a particle size of 10 .mu.m or less,
of 30 wt % of metakaolin; 28 wt % of wallstonite; 20 wt % of talc;
2 wt % of muscovite; and 2 wt % of a castor oil ethylene propylene
oxide-based foam stabilizer was stirred with 50 g of 40 wt %
concentration potassium silicate and 30 g of 17 wt % hydrogen
peroxide aqueous solution at room temperature for 3 minutes. The
resulting mixture was injected into a steel mold, with a size of
approximately 250 mm (length) x approximately 250 mm (width) x
approximately 20 mm (thickness), subjected to a releasing
treatment, and the mold was sealed by a lid. Then, the mold was put
into a drier at 50.degree. C. and the mixture was allowed to foam
and cure for 1 hour. Then, the mold was removed to obtain an
inorganic foamed body 37A. The foamed body 37A was matured at room
temperature for a whole day and night. After the maturing, the
foamed body 37A was dried at 100.degree. C. for 2 hours and then
subjected to a heat treatment at 600.degree. C. for 10 minutes,
thereby obtaining a final product as the inorganic foamed body
37A.
[0060] The performances of the obtained inorganic foamed body 37A
are summarized in Table 1.
TABLE-US-00001 TABLE 1 Performance Item Unit value Density
kg/m.sup.3 225 Thermal conductivity W/mK 0.041 Heat resistance
temperature .degree. C. 1010 Compressive strength kg/cm.sup.2
7.3
[0061] The inorganic foamed body 37A shown in Table 1 is tested by
the following methods. The thermal conductivity is evaluated by
measuring the thermal conductivity according to the plate method
specified in JIS A 1412. The heat resistance temperature is
evaluated as the temperature at which the sample is contracted in
size by 2% when heated in an electric furnace at a temperature
rising rate of 10.degree. C./min. The compressive strength is
evaluated as the maximum compressive strength at 5% compressive
deformation.
[0062] As shown in Table 1, the inorganic foamed body 37A used in
the present invention is light in weight and excellent in heat
resistance and heat insulating properties, satisfies the
requirements for primary heat insulation, and can be foamed into a
prescribed shape. It can be therefore understood that the inorganic
foamed body 37A can be used as the primary heat insulating shaped
body 37.
[0063] An example of the inorganic porous body 37B is next
described (Example 2).
[0064] A mixture of 100 parts by weight of superfine powder
silica-aerogel with a particle size of 50 nm or less manufactured
by Nippon Microtherm Co., Ltd.; 50 parts by weight of fine powder
titanium oxide with a particle size of 1 .mu.m or less; and 8 parts
by weight of glass chopped fiber was mixed with 1 part by weight of
ammonium carbonate as a forming aid agent, and the resulting
mixture was subjected to compression molding at a room temperature.
The molded product was matured under pressure at 125.degree. C. to
obtain an inorganic porous body with a size of approximately 250 mm
(length) x approximately 250 mm (width) x approximately 20 mm
(width) (Note: This method corresponds to the method for producing
Microtherm Block Type of Nippon Microtherm Co., Ltd.).
[0065] The performances of the obtained inorganic porous body 37B
(first primary heat insulating shaped body 37) are summarized in
Table 2.
TABLE-US-00002 TABLE 2 Performance Item Unit value Density in
normal state kg/m.sup.3 360 Density in dry state kg/m.sup.3 350
Thermal conductivity in normal state W/mK 0.028 Thermal
conductivity in dry state W/mK 0.023 Heat Resistance temperature
.degree. C. 1030
[0066] The inorganic porous body 37B shown in Table 2 is tested by
the following methods. The thermal conductivity is evaluated by
measuring the thermal conductivity according to the plate method
specified in JIS A 1412. The heat resistance temperature is
evaluated as the temperature at which the sample is contracted in
size by 2% when heated in an electric furnace at a temperature
rising rate of 10.degree. C./min.
[0067] As shown in Table 2, the inorganic porous body 37B is
excellent in heat resistance and heat insulating properties and
satisfies the requirements for the primary heat insulation.
However, it is slightly insufficient in formability and uses
expensive materials. It is therefore preferred to use it in a part
as a heat insulating shaped body with a simple shape.
[0068] An example of the inorganic staple fiber felt 38A-1 (with
the same shape as 38A in the drawing) (second primary heat
insulating shaped body 38) is next described (Example 3-1).
[0069] A mixture of 40 wt % of rock wool with a fiber length of 100
to 1000 .mu.m obtained by dispersing in water granulated rock wool
composed of 48 wt % of SiO.sub.2, 1 wt % of CaO, 28 wt % of MgO, 19
wt % of Al.sub.2O.sub.3, and 4 wt % in total of other minor
components, defiberizing and cutting the fibers with a pulper, and
removing shot from the dispersion with a cleaner; 40 wt % of
unburned vermiculite with a particle size of 0.5 to 2.0 mm; 10 wt %
of defiberized and purified sepiolite; 3 wt % of a mixture of
potassium titanate and pulp; 2 wt % of 3-denier
polyethylene-polypropylene composite fiber with a fiber length of
approximately 10 mm; and 5 wt % of a thermal self-crosslinking
acrylic resin emulsion with a glass transition point of -14.degree.
C. and a solid content of 45 wt % was dispersed with a mixer to
prepare an approximately 1 wt % aqueous slurry. The aqueous slurry
was formed into a sheet with a rotoformer type sheet making
machine. After suction drying, the sheet was dried at 150.degree.
C. for 20 minutes to obtain a felt with a thickness of
approximately 5 mm. Then, an inorganic staple fiber felt 38A-1 was
prepared by needle-punching a 20 g/m.sup.2 polyester fiber nonwoven
fabric.
[0070] An inorganic staple fiber felt 38A-2 (with the same shape as
38A in the drawing) (second primary heat insulating shaped body 38)
according to another example is described (Example 3-2).
[0071] An inorganic staple fiber felt 38A-2 with a thickness of
approximately 5 mm was prepared in the same manner as in Example
(3-1) from a mixture of 70 wt % of rock wool of Example 1; 10 wt %
of expansive graphite with an average grain size of approximately
1.5 mm; 10 wt % of defiberized and purified sepiolite; 3 wt % of a
mixture of potassium titanate and pulp; 2 wt % of 3-denier
polyethylene-polypropylene composite fiber with a fiber length of
approximately 10 mm; and 5 wt % of a thermal self-cross linking
acrylic resin emulsion with a glass transition point of -14.degree.
C. and a solid content of 45 wt %.
[0072] An inorganic staple fiber felt 38A-3 (with the same shape as
38A in the drawing) according to yet another example is described
(Example 3-3).
[0073] An inorganic staple fiber felt 38A-3 with a thickness
approximately 5 mm was prepared from the same ingredients and in
the same manner as in Example (3-1) except that 40 wt % of ceramic
wool with a fiber length of 100 to 1000 .mu.m obtained by treating
ceramic wool composed of 48 wt % of SiO.sub.2; 48 wt % of
Al.sub.2O.sub.3; and 4 wt % of other minor components in the same
manner as the rock wool of the inorganic foamed body of Example 1
and removing shot therefrom was used.
[0074] The performances of the inorganic staple fiber felts 38A-1
to 38A-3 obtained in Examples (3-1) to (3-3) are summarized in
Table 3.
TABLE-US-00003 TABLE 3 Unit Example (3-1) Example (3-2) Example
(3-3) Thickness mm Approximately Approximately Approximately 5 5 5
Density kg/m.sup.3 240 220 230 Weight (per g/m.sup.2 1200 1100 1150
unit area) Outer -- Good in Good in Good in appearance flexibility
flexibility flexibility (visual and surface and surface and surface
observation) smoothness smoothness smoothness Fireproof -- Flame
Flame Flame retardance retardance retardance grade 1 (non- grade 1
(non- grade 1 (non- combustible) combustible) combustible) Heat
.degree. C. 790 810 980 Resistance temperature Heated Times 2 to 3
4 to 5 2 to 3 expansion factor Thermal W/mK 0.037 0.041 0.036
conductivity (before heated expansion) thermal W/mK 0.031 0.035
0.031 conductivity (after heated expansion)
[0075] The inorganic staple fiber felts 38A-1 to 3 shown in Table 3
are tested by the following methods. The fireproof is evaluated
according to the base material test and surface test specified in
JIS A 1321. The heat resistance temperature is evaluated as the
temperature at which the felt is contracted in size in the
longitudinal and lateral directions by 5% when heated in an
electric furnace at a temperature rising rate of 10.degree. C./min.
The heated expansion factor is the expansion factor in the
thickness direction of the felt which is obtained when it is heated
in an electric furnace at 600.degree. C. for 2 minutes. The thermal
conductivity is evaluated by the thermal conductivity according to
the plate method specified in JIS A 1412. It can be understood from
Table 3 that the inorganic staple fiber felt 38A of this embodiment
is a sheet having heat resistance, heat insulating properties and
flexibility and can be used as an insertion type second primary
heat insulating shaped body 38.
[0076] An example of an inorganic staple fiber circular cylindrical
heat insulating shaped body (secondary heat insulating shaped body
39) is next described (Example 4).
[0077] Onto rock wool with an average fiber diameter of 4 .mu.m
obtained by melting the ingredients of rock wool consisting of 40
wt % of SiO.sub.2; 13 wt % of Al.sub.2O.sub.3; 5 wt % of MgO; 37 wt
% of CaO; and 5 wt % in total of other minor components at 1450 to
1500.degree. C. in an electric furnace and fiberizing the molten
mixture with a 2-wheel type high-speed spinner using a centrifugal
force was sprayed a binder liquid composed of colloidal silica and
a water-soluble melamine resin through a plurality of nozzles
arranged around the spinner to prepare an uncured cotton having
fibers with 5 wt % of solid content coated thereon. Then, the
uncured cotton was wound around a steel core pipe with an outside
diameter approximately 160 mm to a thickness of approximately 20 mm
and thermally cured at 200.degree. C. for 30 minutes in a curing
furnace. The core was removed and the product was cut into a
mating-halves type circular cylindrical heat insulating material.
Then, the circular cylindrical heat insulating material was covered
with a commercially available ALGC (aluminum glass cross) sheet
using a chloroprene adhesive to prepare a rock wool type heat
insulating shaped body as the secondary heat insulating shaped body
39.
[0078] Another example of the inorganic staple fiber circular
cylindrical heat insulating shaped body (secondary heat insulating
shaped body 39) is described below (Example 5).
[0079] Onto glass wool with an average fiber diameter of 6 .mu.m
obtained by melting the ingredients of glass consisting of 63 wt %
of SiO.sub.2; 3 wt % of Al.sub.2O.sub.3; 3 wt % of MgO; 7 wt % of
CaO; 5 wt % of B.sub.2O.sub.3; 5 wt % of K.sub.2O; 12 wt % of
Na.sub.2O; and 2 wt % in total of other minor components at 1350 to
1400.degree. C. in an electric furnace and fiberizing the molten
mixture with a high-speed spinner using a centrifugal force was
sprayed a binder liquid composed of colloidal silica and
water-soluble phenol through a plurality of nozzles arranged around
the spinner to prepare an uncured cotton having fibers with 7 wt %
solid content coated thereon. As in the case with the rock wool of
Example 4, the uncured cotton was wound around a steel core pipe
with an outside diameter of approximately 160 mm to a thickness of
approximately 20 mm and thermally cured at 200.degree. C. for 30
minutes in a curing furnace. The core was removed and the product
was cut into a mating-halves type circular cylindrical heat
insulating material. Then, the circular cylindrical heat insulating
material was covered with a commercially available ALGC (aluminum
glass cross) sheet with a chloroprene adhesive to prepare a glass
wool type heat insulating shaped body as the secondary heat
insulating shaped body 39.
[0080] The performances of the heat insulating shaped bodies
obtained in Examples 4 and 5 are summarized in Table 4.
TABLE-US-00004 TABLE 4 Item Unit Example 4 Example 5 Density of
kg/m.sup.3 95 64 thick part Fireproof -- Flame Flame retardance
retardance (non- grade 1 (non- combustible) combustible) Heat
Resistance .degree. C. 680 400 temperature Thermal W/mK 0.036 0.037
conductivity
[0081] In Example 4 or 5, the thermal conductivity of the thick
part is evaluated using a flat heat-insulating plate shaped with
the same density. As shown in Table 4, the circular cylindrical
heat insulating shaped bodies used in the present invention are
inferior in heat resistance to the primary heat insulating material
but excellent in heat insulating properties, mechanical strength,
moisture proofness, and attaching and covering properties. Also,
since the circular cylindrical heat insulating shaped bodies are
made of inexpensive heat-insulating materials, they can be used as
an economical secondary heat insulating shaped body 39. The
inorganic staple fiber circular cylindrical heat insulating shaped
bodies of Examples 4 and 5 as the secondary heat insulating shaped
body 39 thermally insulate the outside of the first primary heat
insulating shaped body 37.
[0082] The performance evaluation in an example in which the
following heat insulating material is used in the fuel reformer 1
is next described (Example 6-1).
[0083] The first primary heat insulating shaped body 37 has an
outside diameter of approximately 170 mm and a length of
approximately 180 mm and has a recess 20 with an inside diameter of
approximately 90 mm and a depth of approximately 130 mm, the second
primary heat insulating shaped body 38 has an inside diameter of
approximately 90 mm, a thickness of approximately 5 mm and a length
of approximately 390 mm, and the secondary heat insulating shaped
body 39 has an outside diameter of approximately 200 mm, a
thickness of approximately 20 mm, and a length of approximately 640
mm. The first primary heat insulating shaped body 37 composed of
the inorganic foamed body 37A of Example 1, the second primary heat
insulating shaped body 38 composed of the inorganic staple fiber
felt 38A-2 of Example 3-2, and a rock wool type circular
cylindrical secondary heat insulating shaped body 39 of Example 4
were inserted into, attached to and covered a fuel reformer 1 made
of stainless steel and having a combustion chamber 13 (combustion
temperature: 600 to 800.degree. C.) and heat exchanging sections
24, 25 and 26 for thermal insulation and temperature retention such
that the fuel reformer 1 had an outside diameter of approximately
200 mm and a length of approximately 640 mm.
[0084] Next, as another Example (Example 6-2), in the fuel reformer
1 of Example 6-1, the inorganic porous body 37B used in Example 2
was used in place of the inorganic foamed body 37A and the
inorganic staple fiber felt 38A-1 used in Example 3-1 was used in
place of the inorganic staple fiber felt 38A-2 used in Example 3-2
for heat insulation and temperature retention.
[0085] When a fuel gas production test was conducted in Examples
6-1 and 6-2, the production efficiency was high and the outer
temperature of fuel reformer 1 thermally insulated to retain the
temperature thereof was as low as 40 to 50.degree. C. even when the
temperature in the combustion chamber was 600 to 800.degree. C.
That is, the heat insulation and temperature retention using the
heat insulating shaped bodies 37, 38 and 39 according to an
embodiment of the present invention gives excellent results.
[0086] As described in Examples (1 to 6), when heat insulating
materials consisting of a combination of the inorganic foamed body
37A or the inorganic porous body 37B as the first primary heat
insulating shaped body 37, the annular inorganic staple fiber felt
38A-1 or 38A-2 as the primary heat insulating shaped body 38, and
the circular cylindrical secondary heat insulating shaped body 39
of these Examples are inserted into, attached to and cover the fuel
reformer 1 for the purpose of heat insulation and temperature
retention of the fuel reformer 1, high-temperature heat insulation
and temperature retention which improve the fuel gas production
efficiency can be achieved. Also, since the heat insulating shaped
bodies 37, 38 and 39 of Examples (1 to 6) are light in weight and
high in maintainability and are easy to be inserted into, be
attached to and cover the fuel reformer 1 and since they are formed
based on inexpensive materials, they have an effect of being able
to provide economical heat insulation and temperature retention and
being excellent in practicality. When the inorganic combined body
37C is used as the first primary heat insulating shaped body 37 or
when the inorganic staple fiber felt 38A-3 is used as the second
primary heat insulating shaped body 38, the similar effect can be
achieved.
BRIEF DESCRIPTION OF DRAWINGS
[0087] FIG. 1 is a cross-sectional view illustrating the
configuration of a fuel reformer of the present invention.
DESCRIPTION OF REFERENCE NUMERALS AND SYMBOLS
[0088] 1: fuel reformer [0089] 3: opening [0090] 11: combustion
material introducing section [0091] 12: burner [0092] 13:
combustion chamber [0093] 13A: combustion cylinder [0094] 14:
reforming catalyst layer [0095] 15: shift catalyst layer [0096] 16:
selective oxidation catalyst layer [0097] 17: first primary heat
insulating section [0098] 18: second primary heat insulating
section [0099] 19: secondary heat insulating section [0100] 20:
recess [0101] 21: combustion flue gas passage [0102] 22: raw
material gas passage [0103] 23: reformate passage [0104] 24, 25,
26: heat exchanging section [0105] 31: raw material introduction
port [0106] 32: combustion flue gas outlet [0107] 33: raw material
gas inlet [0108] 34: reformate outlet [0109] 35: selective
oxidation air inlet [0110] 36: ceiling portion [0111] 37: first
primary heat insulating shaped body [0112] 37A: inorganic foamed
body [0113] 37B: inorganic porous body [0114] 37C: inorganic
combined body [0115] 38: second primary heat insulating shaped body
[0116] 38A: inorganic staple fiber felt [0117] 39: secondary heat
insulating shaped body [0118] 40: outer skin material [0119] 41 to
47: partition [0120] D: combustion gas [0121] E: combustion air
[0122] F: combustion flue gas [0123] G: raw material gas [0124] H:
water [0125] J: fuel gas [0126] M: reformate
* * * * *