Chemistry: electrical current producing apparatus – product – and – With pressure equalizing means for liquid immersion operation
Reexamination Certificate
2000-08-15
2003-05-13
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
With pressure equalizing means for liquid immersion operation
C429S006000, C429S006000, C429S006000, C427S115000
Reexamination Certificate
active
06562505
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a sealing structure of a cell tube of tubular type fuel cell, which increases sealability of the cell tube to enhance the electrical characteristics of the fuel cell.
2. Description of the Related Art
FIG. 3
outlines the structure of a tubular type solid electrolyte fuel cell module.
FIG. 4
is a perspective schematic view of a cell tube portion of the module.
FIG. 5
is a schematic structural view of a sealing structure at the end of the cell tube.
As shown in
FIG. 3
, a top plate
02
, an upper tube sheet
03
and a lower tube sheet
04
are disposed in a module body
01
surrounded by a heat insulator. Below the lower tube sheet
04
, a cell chamber
01
a
is formed. Between the top plate
02
and the upper tube sheet
03
of the module body
01
, a fuel supply chamber
05
is formed. Between the upper tube sheet
03
and the lower tube sheet
04
, a fuel discharge chamber
06
is formed. To the top plate
02
of the fuel supply chamber
05
, an external pipe
07
for establishing communication between the fuel supply chamber
05
and the outside of the module body
01
is connected in such a manner as to pass through the module body
01
. Inside of the external pipe
07
, an internal pipe
08
passing through the upper tube sheet
03
is disposed for establishing communication between the fuel discharge chamber
06
and the outside of the module body
01
.
Cell tubes
010
, each comprising unit cell films (not shown) formed on an outer peripheral surface thereof, pass through and are supported by the lower tube sheet
04
such that the upper end of the cell tube
010
is positioned in the fuel discharge chamber
06
, and that a lower portion of the cell tube
010
is positioned in the cell chamber
01
a
of the module body
01
. Inside the cell tube
010
, a fuel injection pipe
011
passing through the upper tube sheet
03
is disposed for establishing communication between the inner lower portion of the cell tube
010
and the interior of the fuel supply chamber
05
. Inside the injection pipe
011
, a current collecting rod
012
is disposed which has an upper end positioned in the fuel supply chamber
05
and a lower end positioned near the lower end of the cell tube
010
. The lower end of the current collecting rod
012
is coupled to a current collecting member
013
which is electrically connected to the above-mentioned unit cell films and which closes the lower end of the cell tube
010
. The upper end of the current collecting rod
012
is electrically connected to the outside of the module body
01
via a current collecting member
013
of nickel and a conductive rod
014
.
To the upper end of the cell tube
010
, a current collecting connector
015
electrically connected to the unit cell films is attached. The current collecting connector
015
is series connected to other cell tubes
01
via the same current collecting connectors
015
.
In a lower portion of the cell chamber
01
a
of the module body
01
, a partition plate
016
of a porous ceramic material is provided. Below the partition plate
016
, an air preheating chamber
017
communicating with the cell chamber
01
a
via the partition plate
016
is provided. To the air preheating chamber
017
, an air supply pipe
018
communicating with the outside of the module body
01
is connected. Inside the cell chamber
01
a
of the module body
01
, an end of an air discharge pipe
019
is located. The air discharge pipe
019
has the other end located outside the module body
01
, and its intermediate portion is disposed in such a manner as to pass through the interior of the air preheating chamber
017
for the purpose of heat exchange.
The cell tube
010
suspended from the lower tube sheet
04
of the module body
01
, as shown in
FIGS. 4 and 5
, is formed by laminating a fuel electrode
032
a,
an electrolyte
032
b,
and an air electrode
032
c
in this order on a surface of a substrate tube
031
, and further laminating a dense conductive connecting material (interconnector)
033
for connecting the fuel electrode and the air electrode. In this manner, a plurality of unit cell films
032
are formed in a lateral-striped pattern. That is, the unit cell film
032
is constituted by the fuel electrode
032
a,
the solid electrolyte
032
b,
and the air electrode
032
c
laminated on the substrate tube
031
. The interconnectors
033
each seal the interface between the inside and the outside of the substrate tube
031
in the space between the unit cell films
032
, thus connecting the unit cell films
032
in series.
The film configuration of a sealed portion of the foregoing cell tube
010
will be described with reference to
FIGS. 5 and 6
.
As shown in
FIGS. 5 and 6
, a lead film (Ni—Al)
034
connected via the interconnector
033
to the air electrode
032
c
and located on the outer surface of the substrate tube (15%CaO—ZrO
2
)
031
is formed on the outer peripheral surface of a lower end portion of the substrate tube
031
. The lead film
034
is provided with a current collecting terminal member
013
, from which current is collected by the current collecting rod
012
. On the upper surface of the lead film
034
, an airtight film (Al
2
O
3
)
035
with high airtight properties is formed. A cap-like sealing member
037
is bonded to the airtight film
035
via an inorganic adhesive
036
. A similar sealing structure is provided for the outer peripheral surface near the upper end, beside the aforementioned tube sheet
04
, of the substrate tube
031
. The airtight film
035
is minimally porous as indicated by its porosity of about 5 to 10%, and thus prevents an escape of gas. Moreover, the airtight film
035
has a relatively large thickness of about 100 to 150 &mgr;m to prevent oxidation of the lead film
034
located underneath.
The actions of the tubular type solid electrolyte fuel cell module with the foregoing structure will be described. The interior of the cell chamber
01
a
of the module body
01
is heated to an operating temperature (about 900 to 1,000° C.). A fuel gas
020
such as hydrogen is supplied through the external pipe
07
, while air
021
as an oxidant gas is supplied through the air supply pipe
018
. The fuel gas
020
fed through the external pipe
07
flows from the fuel supply chamber
05
to the lower end of the cell tube
010
via the injection pipe
011
. On the other hand, the air
021
that has passed through the partition plate
016
via the air preheating chamber
017
flows into the cell chamber
01
a.
The fuel gas
020
permeates through the porous substrate tube
031
, and is fed to the fuel electrode
032
a
of the unit cell film
032
. Whereas the air (oxygen)
021
contacts the air electrode
032
c.
At this time, the unit cell film
032
reacts the hydrogen and the air (oxygen) electrochemically to generate power. This power is transmitted to the outside via the current collecting member
013
, current collecting rod
012
, current collecting member
013
, and conductive rod
014
. A residual fuel gas
022
remaining after power generation flows into the fuel discharge chamber
06
from the upper end of the cell tube
010
, and is discharged to the outside via the internal pipe
08
for reuse. Residual air
023
remaining after power generation is discharged to the outside via the air discharge pipe
019
.
The above-described cell tube
010
has so far been laborious to produce, because the fuel electrode
032
a,
electrolyte
032
b,
and air electrode
032
c
are sequentially formed as films on the surface of the substrate tube
031
by means of a thermal spray gun
040
as shown in FIG.
7
(A). Moreover, there has been a raw material loss
041
during film formation owing to the spraying of raw materials from the thermal spray gun
040
, and the production cost has been high. Thus, a low cost for mass production has been desired.
Under these circumstances, a proposal has been made for a sintering process performed by forming films of raw materials for the fuel ele
Hisatome Nagao
Houjyou Tohru
Tsukuda Hiroshi
Watanabe Yoshiharu
Alejandro R
Birch Stewart Kolasch & Birch, LLP.
Mitsubishi Heavy Industries Ltd.
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