U.S. patent application number 14/597650 was filed with the patent office on 2015-07-09 for voltage lead jumper connected fuel cell columns.
The applicant listed for this patent is Bloom Energy Corporation. Invention is credited to Matthias GOTTMANN, Martin PERRY.
Application Number | 20150194695 14/597650 |
Document ID | / |
Family ID | 41505434 |
Filed Date | 2015-07-09 |
United States Patent
Application |
20150194695 |
Kind Code |
A1 |
GOTTMANN; Matthias ; et
al. |
July 9, 2015 |
VOLTAGE LEAD JUMPER CONNECTED FUEL CELL COLUMNS
Abstract
A fuel cell system includes a plurality of fuel cell stacks, and
one or more devices which in operation of the system provide an
azimuthal direction to one or more anode or cathode feed or exhaust
fluid flows in the system.
Inventors: |
GOTTMANN; Matthias;
(Sunnyvale, CA) ; PERRY; Martin; (Sunnyvale,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bloom Energy Corporation |
Sunnyvale |
CA |
US |
|
|
Family ID: |
41505434 |
Appl. No.: |
14/597650 |
Filed: |
January 15, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12458171 |
Jul 2, 2009 |
8968958 |
|
|
14597650 |
|
|
|
|
61129621 |
Jul 8, 2008 |
|
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|
Current U.S.
Class: |
429/455 |
Current CPC
Class: |
H01M 2/202 20130101;
H01M 8/04022 20130101; Y02E 60/10 20130101; Y02E 60/50 20130101;
H01M 8/0631 20130101; H01M 8/249 20130101; H01M 8/04074 20130101;
H01M 8/2475 20130101; H01M 8/0618 20130101 |
International
Class: |
H01M 8/24 20060101
H01M008/24; H01M 8/04 20060101 H01M008/04 |
Claims
1. A fuel cell system, comprising: a plurality of vertical fuel
cell columns, each fuel cell column comprising at least one fuel
cell stack, wherein the at least one fuel cell stack comprises a
plurality of horizontal fuel cells stacked vertically; a voltage
lead jumper which electrically connects top ends of adjacent two of
the plurality of vertical fuel cell columns such that the adjacent
two vertical fuel cell columns form a column pair in which the
columns are electrically connected in series; and an electrical
output located on a bottom end of each of the adjacent two vertical
fuel cell columns; wherein each of the plurality of vertical fuel
cell columns comprises a plurality of fuel cell stacks, wherein a
first fuel cell stack in a first fuel cell column is separated from
an adjacent second fuel cell stack in the first fuel cell column by
an anode feed/return assembly; and wherein the plurality of
vertical fuel cell columns comprise solid oxide fuel cell columns
and the solid oxide fuel cell columns and the voltage lead jumper
are enclosed in a housing.
2. The system of claim 1, wherein: the electrical outputs comprise
current collection rods which extend through a bottom surface of
the system and are electrically connected to a power conditioning
module or device.
3. The system of claim 2, wherein the voltage lead jumper comprises
a flexible, thermally and electrically insulating sleeve enclosing
a metal or metal alloy wire.
4. The system of claim 1, wherein the voltage lead jumper is
located in an integrated solid oxide fuel cell and fuel processor
unit.
5. The system of claim 4, wherein the housing comprises a hot box,
and the voltage lead jumper is located in the hot box.
6. The system of claim 5, wherein: the voltage lead jumper
electrically connects top ends of adjacent two of the plurality of
vertical fuel cell columns in the hot box; and the electrical
outputs extend through a bottom surface of the hot box and are
electrically connected to a power conditioning module or
device.
7. The system of claim 6, wherein: a top electrical output of a
first vertical fuel cell column in the column pair is electrically
connected to a top electrical output of a second vertical fuel cell
column in the column pair using the voltage lead jumper; a bottom
electrical output of the first vertical fuel cell column in the
column pair is electrically connected to the power conditioning
module or device; and a bottom electrical output of the second
vertical fuel cell column in the column pair is electrically
connected to the power conditioning module or device.
8. The system of claim 7, further comprising a plurality of column
pairs in the hot box.
9. The system of claim 8, wherein each of the plurality of column
pairs comprises the voltage lead jumper which connects a top
electrical output of a first vertical fuel cell column in the
column pair to a top electrical output of a second vertical fuel
cell column in the column pair.
10. The system of claim 1, wherein the housing comprises a bottom
surface; and wherein the electrical outputs comprise current
collection rods which extend through the bottom surface.
Description
CROSS REFERENCE TO RELATED PATENT APPLICATIONS
[0001] The present application is a Continuation of U.S. patent
application Ser. No. 12/458,171, filed Jul. 2, 2009, and which
claims the benefit of U.S. Provisional Patent Application No.
61/129,621, filed Jul. 8, 2008, the entire contents of all of which
are incorporated herein by reference.
BACKGROUND
[0002] The present invention relates generally to fuel cell systems
and more specifically to fuel cell systems containing recuperators
or heat exchangers with spiral flow and methods of operating
same.
[0003] FIGS. 1-9 illustrate a prior art fuel cell system described
in U.S. Published Application 2007/0196704 A1 published on Aug. 23,
2007 (filed as Ser. No. 11/656,563 on Jan. 23, 2007) titled
Integrated Solid Oxide Fuel Cell And Fuel Processor and
incorporated herein by reference in its entirety. Specifically,
with reference to FIGS. 1, 2A, 2B and 3A, an integrated fuel cell
unit 10 is shown in form of an integrated solid oxide fuel cell
("SOFC")/fuel processor 10 having a generally cylindrical
construction. The unit 10 includes an annular array 12 of eight (8)
fuel cell stacks 14 surrounding a central axis 16, with each of the
fuel cell stacks 14 having a stacking direction extended parallel
to the central axis 16, with each of the stacks having a face 17
that faces radially outward and a face 18 that faces radially
inward. As best seen in FIG. 3A the fuel cell stacks 14 are spaced
angularly from each other and arranged to form a ring-shaped
structure about the axis 16. Because there are eight of the fuel
cell stacks 14, the annular array 12 could also be characterized as
forming an octagon-shaped structure about the axis 16. While eight
of the fuel cell stacks 14 have been shown, it should be understood
that the invention contemplates an annular array 12 that may
include more than or less than eight fuel cell stacks.
[0004] With reference to FIG. 1, the unit 10 further includes an
annular cathode recuperator 20 located radially outboard from the
array 12 of fuel stacks 14, an annular anode recuperator 22 located
radially inboard from the annular array 12, a reformer 24 also
located radially inboard of the annular array 12, and an annular
anode exhaust cooler/cathode preheater 26, all integrated within a
single housing structure 28. The housing structure 28 includes an
anode feed port 30, an anode exhaust port 32, a cathode feed port
34, a cathode exhaust port 36, and an anode combustion gas inlet
port 37. An anode exhaust combustor (typically in the form an anode
tail gas oxidizer (ATO) combustor), shown schematically at 38, is a
component separate from the integrated unit 10 and receives an
anode exhaust flow 39 from the port 32 to produce an anode
combustion gas flow 40 that is delivered to the anode combustion
gas inlet 37. During startup, the combustor 38 also receives a fuel
flow (typically natural gas), shown schematically by arrow 41.
Additionally, some of the anode exhaust flow may be recycled to the
anode feed port 30, as shown by arrows 42. In this regard, a
suitable valve 43 may be provided to selectively control the
routing of the anode exhaust flow to either the combustor 38 or the
anode feed port 30. Furthermore, although not shown, a blower may
be required in order to provide adequate pressurization of the
recycled anode exhaust flow 42. While FIGS. 1, 2A and 2B are
section views, it will be seen in the later figures that the
components and features of the integrated unit 10 are symmetrical
about the axis 16, with the exception of the ports 34, 36 and
37.
[0005] With reference to FIG. 1 and FIG. 2A, the cathode flows will
be explained in greater detail. As seen in FIG. 1, a cathode feed
(typically air), shown schematically by arrows 44, enters the unit
10 via the port 34 and passes through an annular passage 46 before
entering a radial passage 48. It should be noted that as used
herein, the term "radial passage" is intended to refer to a passage
wherein a flow is directed either radially inward or radially
outward in a generally symmetric 360 degree pattern. The cathode
feed 44 flows radially outward through the passage 48 to an annular
passage 50 that surrounds the array 12 and passes through the
cathode recuperator 20. The cathode feed 44 flows downward through
the annular passage 50 and then flows radially inward to an annular
feed manifold volume 52 that surrounds the annular array 12 to
distribute the cathode feed 44 into each of the fuel cell stacks 14
where the cathode feed provides oxygen ions for the reaction in the
fuel cell stacks 14 and exits the fuel cell stacks 14 as a cathode
exhaust 56. The cathode exhaust 56 then flows across the reformer
24 into an annular exhaust manifold area 58 where it mixes with the
combustion gas flow 40 which is directed into the manifold 58 via
an annular passage 60. In this regard, it should be noted that the
combustion gas flow 40 helps to make up for the loss of mass in the
cathode exhaust flow 56 resulting from the transport of oxygen in
the fuel cell stacks 14. This additional mass flow provided by the
combustion gas flow 40 helps in minimizing the size of the cathode
recuperator 20. The combined combustion gas flow 40 and cathode
exhaust 56, shown schematically by arrows 62, exits the manifold 58
via a central opening 64 to a radial passage 66. The combined
exhaust 62 flows radially outward through the passage 66 to an
annular exhaust flow passage 68 that passes through the cathode
recuperator 20 in heat exchange relation with the passage 50 to
transfer heat from the combined exhaust 62 to the cathode feed 44.
The combined exhaust 62 flows upward through the annular passage 68
to a radial passage 70 which directs the combined exhaust 62
radially inward to a final annular passage 72 before exiting the
unit 10 via the exhaust port 36.
[0006] With reference to FIG. 1 and FIG. 2B, an anode feed, shown
schematically by arrows 80, enters the unit 10 via the anode feed
inlet port 30 preferably in the form of a mixture of recycled anode
exhaust 42 and methane. The anode feed 80 is directed to an annular
passage 82 that passes through the anode recuperator 22. The anode
feed 80 then flows to a radial flow passage 84 where anode feed 80
flows radially outward to an annular manifold or plenum 86 that
directs the anode feed into the reformer 24. After being reformed
in the reformer 24, the anode feed 80 exits the bottom of reformer
24 as a reformate and is directed into an integrated pressure
plate/anode feed manifold 90. The feed manifold 90 directs the
anode feed 80 to a plurality of stack feed ports 92, with one of
the ports 92 being associated with each of the fuel cell stacks 14.
Each of the ports 92 directs the anode feed 80 into a corresponding
anode feed/return assembly 94 that directs the anode feed 82 into
the corresponding fuel cell stack 14 and collects an anode exhaust,
shown schematically by arrows 96, from the corresponding stack 14
after the anode feed reacts in the stack 14. Each of the anode
feed/return assemblies 94 directs the anode exhaust 96 back into a
corresponding one of a plurality of stack ports 98 in the pressure
plate/manifold 90 (again, one port 98 for each of the fuel cell
stacks 14). The manifold 90 directs the anode exhaust 96 radially
inward to eight anode exhaust ports 100 (again, one for each stack
14) that are formed in the pressure plate/manifold 90. The anode
exhaust 96 flows through the ports 100 into a plurality of
corresponding anode exhaust tubes 102 which direct the anode
exhaust 96 to a radial anode exhaust flow passage 104. The anode
exhaust 96 flows radially inward through the passage 104 to an
annular flow passage 106 that passes downward through the anode
recuperator 22 in heat exchange relation with the flow passage 82.
The anode exhaust 96 is then directed from the annular passage 106
upward into a tubular passage 108 by a baffle/cover 110 which is
preferably dome-shaped. The anode exhaust 96 flows upwards through
the passage 108 before being directed into another annular passage
112 by a baffle/cover 114, which again is preferably dome-shaped.
The annular passage 112 passes through the anode cooler 26 in heat
exchange relation with the annular cathode feed passage 46. After
transferring heat to the cathode feed 44, the anode exhaust 96
exits the annular passage 112 and is directed by a baffle 116,
which is preferably cone-shaped, into the anode exhaust port
32.
[0007] With reference to FIGS. 3A, 3B, the reformer 24 is provided
in the form of an annular array 280 of eight tube sets 282, with
each tube set 282 corresponding to one of the fuel cell stacks 14
and including a row of flattened tubes 284. In this regard, it
should be noted that the number of tubes 284 in the tube sets 282
will be highly dependent upon the particular parameters of each
application and can vary from unit 10 to unit 10 depending upon
those particular parameters.
[0008] FIG. 3C is intended as a generic figure to illustrate
certain construction details common to the cathode recuperator 20,
the anode recuperator 22, and the anode cooler 26. The construction
of each of these three heat exchangers basically consists of three
concentric cylindrical walls A, B, C that define two separate flow
passages D and E, with corrugated or serpentine fin structures G
and H provided in the flow passages D and E, respectively, to
provide surface area augmentation of the respective flow passages.
Because the heat transfer occurs through the cylindrical wall B, it
is preferred that the fins G and H be bonded to the wall B in order
to provide good thermal conductivity, such as by brazing. On the
other hand, for purposes of assembly and/or allowing differential
thermal expansion, it is preferred that the fins G and H not be
bonded to the cylindrical walls A and C. For each of the heat
exchangers 20, 22 and 26, it should be understood that the
longitudinal length and the specific geometry of the fins G and H
in each of the flow paths D and E can be adjusted as required for
each particular application in order to achieve the desired output
temperatures and allowable pressure drops from the heat
exchangers.
[0009] Turning now to FIG. 4A-D, the anode cooler 26 includes a
corrugated or serpentine fin structure 300 to provide surface area
augmentation for the anode exhaust 96 in the passage 112, a
corrugated or serpentine fin structure 302 that provides surface
area augmentation for the cathode feed flow 44 in the passage 46,
and a cylindrical wall or tube 304 to which the fins 300 and 302
are bonded, preferably by brazing, and which serves to separate the
flow passage 46 from the flow passage 112. As best seen in FIG. 4B,
a cylindrical flow baffle 306 is provided on the interior side of
the corrugated fin 300 and includes the dome-shaped baffle 114 on
its end in order to define the inner part of flow passage 112. A
donut-shaped flow baffle 308 is also provided to direct the cathode
feed 44 radially outward after it exists the flow passage 46. The
cone-shaped baffle 116 together with the port 32 are attached to
the top of the tube 304, and include a bolt flange 310 that is
structurally fixed, by a suitable bonding method such as brazing or
welding, to the port 32, which also includes a bellows 311 to allow
for thermal expansion between the housing 28 and the components
connected through the flange 310. As seen in FIG. 4C, the
above-described components can be assembled as yet another
subassembly that is bonded together, such as by brazing.
[0010] In reference to FIGS. 1 and 4D, it can be seen that the
anode recuperator 22 includes a corrugated or serpentine fin
structure 312 (best seen in FIG. 8) in the annular flow passage 82
for surface area augmentation for anode feed 80. As best seen in
FIG. 1, the anode recuperator 22 further includes another
corrugated or serpentine fin structure 314 in the annular flow
passage 106 for surface augmentation of the anode exhaust 96.
[0011] As best seen in FIG. 4D, corrugated fins 312 and 314 are
preferably bonded to a cylindrical wall of tube 316 that serves to
separate the flow passages 82 and 106 from each other, with the
dome-shaped baffle 110 being connected to the bottom end of the
wall 316. Another cylindrical wall or tube 320 is provided radially
inboard from the corrugated fin 314 (not shown in FIG. 4D, but in a
location equivalent to fin 300 in cylinder 304 as seen in FIG. 4B)
to define the inner side of the annular passage 106, as best seen
in FIG. 4D. As seen in FIG. 2A, an insulation sleeve 322 is
provided within the cylindrical wall 320 and a cylindrical exhaust
tube 324 is provided within the insulation sleeve 322 to define the
passage 108 for the anode exhaust 96. Preferably, the exhaust tube
324 is joined to a conical-shaped flange 328 provided at a lower
end of the cylindrical wall 320. With reference to FIG. 4D, another
cylindrical wall or tube 330 surrounds the corrugated fin 312 to
define the radial outer limit of the flow passage 82 and is
connected to the inlet port 30 by a conical-shaped baffle 332. A
manifold disk 334 is provided at the upper end of the wall 316 and
includes a central opening 336 for receiving the cylindrical wall
320, and eight anode exhaust tube receiving holes 338 for sealingly
receiving the ends of the anode exhaust tubes 102, with the plate
308 serving to close the upper extent of the manifold plate 334 in
the assembled state.
[0012] With reference to FIGS. 2B and 4E, a heat shield assembly
350 is shown and includes an inner cylindrical shell 352 (shown in
FIG. 2B), an outer cylindrical shell 354, an insulation sleeve 356
(shown in FIG. 2B) positioned between the inner and outer shells
352 and 354, and a disk-shaped cover 358 closing an open end of the
outer shell 350. The cover 358 includes eight electrode clearance
openings 360 for through passage of the electrode sleeves 211. As
seen in FIG. 4E, the heat shield assembly 350 is assembled over an
insulation disk 361 the outer perimeter of the assembled array 12
of fuel cells 14 and defines the outer extent of the cathode feed
manifold 52. The heat shield 350 serves to retain the heat
associated with the components that it surrounds. FIG. 5 shows the
heat shield assembly 350 mounted over the stacks 14.
[0013] With reference to FIG. 1 and FIG. 6, the cathode recuperator
20 includes a corrugated or serpentine fin structure 362 to provide
surface enhancement in the annular flow passage 68 for the combined
exhaust 62, a corrugated or serpentine fin structure 364 to provide
surface enhancement in the annular flow passage 50 for the cathode
feed 44, and a cylindrical tube or wall 366 that separates the flow
passages 50 and 68 and to which the fins 362 and 364 are bonded. A
disk-shaped cover plate 368 is provided to close the upper opening
of the cylindrical wall 366 and includes a central opening 370, and
a plurality of electrode clearance openings 372 for the passage of
the electrode sleeve 211 therethrough. A cylindrical tube or sleeve
376 is attached to the cover 368 to act as an outer sleeve for the
anode cooler 26, and an upper annular bolt flange 378 is attached
to the top of the sleeve 376. A lower ring-shaped bolt flange 380
and an insulation sleeve 382 are fitted to the exterior of the
sleeve 376, and a cylindrical wall or shield 384 surrounds the
insulation sleeve 382 and defines an inner wall for the passage 72,
as best seen in FIGS. 1 and 6.
[0014] With reference to FIG. 7, the components of FIG. 6 are then
assembled over the components shown in FIG. 5 with the flange 378
being bolted to the flange 310.
[0015] With reference to FIG. 4A, the outer housing 28 is assembled
over the remainder of the unit 10 and bolted thereto at flange 380
and a flange 400 of the housing 28, and at flange 402 of the
assembly 237 and a flange 404 of the housing 28, preferably with a
suitable gasket between the flange connections to seal the
connections.
[0016] FIG. 9 is a schematic representation of the previously
described integrated unit 10 showing the various flows through the
integrated unit 10 in relation to each of the major components of
the integrated unit 10. FIG. 9 also shows an optional air cooled
anode condenser 460 that is preferably used to cool the anode
exhaust flow 39 and condense water therefrom prior to the flow 39
entering the combustor 38. If desired, the condenser may be
omitted. FIG. 9 also shows a blower 462 for providing an air flow
to the combustor 38, a blower 464 for providing the cathode feed
44, and a blower 466 for pressurizing the anode recycle flow 42. If
desired, in an alternate embodiment of the unit 10 shown in FIG. 9
also differs from the previously described embodiment shown in FIG.
1 in that an optional steam generator (water/combined exhaust heat
exchanger) 440 is added in order to utilize waste heat from the
combined exhaust 62 to produce steam during startup. In this
regard, a water flow 442 is provided to a water inlet port 444 of
the heat exchanger 440, and a steam outlet port directs a steam
flow 448 to be mixed with the anode feed 80 for delivery to the
anode feed inlet port 30.
SUMMARY
[0017] One embodiment of the invention provides a fuel cell system,
comprising a plurality of fuel cell stacks, and one or more devices
which in operation of the system provide an azimuthal direction to
one or more anode or cathode feed or exhaust fluid flows in the
system.
[0018] Another embodiment of the invention provides a method of
operating a fuel cell system which includes a plurality of fuel
cell stacks, the method comprising providing an azimuthal direction
to one or more anode or cathode feed or exhaust fluid flows in the
system.
[0019] Another embodiment of the invention provides a fuel cell
system, comprising a plurality of vertical fuel cell columns, each
fuel cell column comprising at least one fuel cell stack, a voltage
lead jumper which electrically connects one end of adjacent two of
the plurality of vertical fuel cell columns, and electrical outputs
for each adjacent two of the plurality of vertical fuel cell
columns located on a second end thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a sectional view of a prior art fuel cell unit
with an integrated SOFC and fuel processor embodying the present
invention;
[0021] FIGS. 2A and 2B are sectional views showing one half of the
fuel cell unit of FIG. 1, with FIG. 2A illustrating the flows of
the cathode feed and exhaust gases and FIG. 2B illustrating the
flows of the anode feed and exhaust gases;
[0022] FIG. 3A is a sectional view taken from line 3A-3A in FIG. 1,
but showing only selected components of the fuel cell unit;
[0023] FIG. 3B is an enlarged, somewhat schematic view taken from
line 3B-3B in FIG. 3A;
[0024] FIG. 3C is a partial section view illustrating construction
details common to several heat exchangers contained within the
integrated unit of FIG. 1;
[0025] FIGS. 4A and 4B are exploded perspective views of the
components of an anode exhaust cooler of the integrated unit of
FIG. 1;
[0026] FIG. 4C is a perspective view showing the components of
FIGS. 4A and B in their assembled state;
[0027] FIG. 4D is an exploded perspective view showing the
assembled components together with an anode recuperator of the
integrated unit of FIG. 1;
[0028] FIG. 4E is an exploded perspective view showing the
components of the fuel cell stacks, anode recuperator and anode
cooler together with an insulation disk and heat shield housing of
the integrated unit of FIG. 1;
[0029] FIG. 5 is a perspective view showing the assembled state of
the components of FIG. 4E;
[0030] FIG. 6 is an exploded perspective view showing a cathode
recuperator assembly together with other components of the
integrated unit of FIG. 1;
[0031] FIG. 7 is an exploded perspective view showing the assembled
components of FIG. 6 together with the assembled components of FIG.
4;
[0032] FIG. 8 is an exploded perspective view showing the assembled
components of FIG. 7 together with an outer housing of the
integrated unit of FIG. 1;
[0033] FIG. 9 is a schematic representation of the fuel cell unit
if FIG. 1.
[0034] FIGS. 10A-10E are three dimensional views of an assembly
according to the first embodiment of the invention.
[0035] FIG. 11A is three dimensional view of an unit according to
the second embodiment of the invention. FIGS. 11B and 11C are side
view and side cross sectional view, respectively, of a bottom
portion of the unit of FIG. 11A.
[0036] FIGS. 12A and 12B are exploded perspective views of
components of the third embodiment of the invention.
[0037] FIG. 13A is three dimensional view of an unit according to
the fourth embodiment of the invention. FIGS. 13B and 13C are side
views of portion of the unit of FIG. 13A.
[0038] FIGS. 13D and 13E are three dimensional views of heat
exchangers according to the fourth embodiment of the invention.
FIGS. 13F and 13G are side views of a portion of the heat exchanger
of FIG. 13D and FIG. 13H is a side view of a portion of the heat
exchanger of FIG. 13E.
[0039] FIG. 14 is a three dimensional view of a jumper according to
a fifth embodiment of the invention.
DETAILED DESCRIPTION
[0040] In the embodiments of the invention, the present inventors
realized that in the prior art unit 10 shown in FIGS. 1-9, the
azimuthal flow mixing could be improved to avoid flow streams
concentrating hot zones or cold zones on one side of the hot box 28
or another. Azimuthal flow as used herein includes flow in angular
direction that curves away in a clockwise or counterclockwise
direction from a straight line representing a radial direction from
a center of a cylinder to an outer wall of the cylinder, and
includes but is not limited to rotating, swirling or spiraling
flow. The embodiments of the invention provide several methods and
structures for introducing swirl to the fluid flows in the unit 10
to promote more uniform operating conditions, such as temperature
and composition of the fluid flows, such as the cathode exhaust
flow 56.
[0041] Thus, in the embodiments of the invention, an improved
structure and method are provided to move or mix the cathode
airstreams (e.g., the cathode or air exhaust streams) 56 coming out
of the fuel cell stacks 14 shown in FIGS. 1-9. This would allow for
mixing of heat between fuel cell columns or stacks. A hotter radial
section of the hot box (the air flow tends to not mix in the radial
direction) can transfer its heat to a cooler section of the hot box
and vice versa for a cooler section of the hot box. In this way the
radial temperature gradients can be decreased. In the embodiments
of the invention, the anode tail gas oxidizer 38 may comprise a
cylindrical tube or two concentric cylindrical tubes extending
parallel to the central axis of the unit 10 and located between the
anode recuperator 22 and the reformer tubes 24 (instead being
located of outside of the housing or hot box 28).
[0042] In the first embodiment of the invention, a turning vane
assembly 501 is provided to move heat azimuthally and/or radially
across the hot box to reduce radial temperature gradients. FIG. 10A
shows one exemplary structure of the turning vane assembly 501. In
one embodiment, the assembly 501 may be located in place of the
central opening 64 above the pressure plate 90 shown in FIG. 1.
Alternatively, the assembly 501 may be located below pressure plate
90 (e.g., between plate 90 and the bottom plate 239 of housing 28)
inside passage 66 shown in FIG. 1.
[0043] As discussed with respect to FIGS. 1, 2A and 9 above, the
cathode exhaust 56 flows out of the stacks 14 and down through
manifold 58 toward passage 66. If desired, the cathode exhaust 56
may be mixed with the output flow 40 of the ATO 38. However,
instead of passing straight down through the central opening 64
into the radial passage 66, the cathode exhaust is provided to the
turning vane assembly 501 which azimuthally redirects the cathode
exhaust 56 and optional the ATO output 40 flows into the radial
passage 66. The amount of redirection can be varied depending on
the length and number of vanes.
[0044] FIG. 10B shows an exemplary counterclockwise azimuthal flow
direction of cathode exhaust 56 through assembly 501 where the flow
has an angular component and a vertical component (e.g., up to down
component). If desired, the turning vane assembly 501 may also
exhaust the air in a radial ("r"-hat) direction into passage 66
(e.g., in a line or ray from the central axis toward the outer wall
of housing 28) after being rotated in the azimuthal direction in
assembly 501 in order to minimize pressure drop, as shown in FIG.
10C. In other words, the cathode exhaust 56 may be rotated in the
azimuthal direction in the assembly 501 and then provided into the
radial passage 66 either in the azimuthal direction (as shown in
FIG. 10B) or in the radial direction (as shown in FIG. 10C).
[0045] As shown in FIG. 10A, the assembly 501 may comprise two or
more vanes 503 (which may also be referred to as deflectors or
baffles) located inside an enclosure 505. The enclosure contains
side and bottom surfaces (where the bottom surface may comprise the
top surface of the plate 90), but is generally open on top to
receive the cathode exhaust 56 flow. The vanes 503 may be curved as
shown in FIG. 10A or they may be straight. Preferably, the vanes
503 are curved such that the shape of turning vane 503 curve is in
a golden ratio arc or in catenary curve shape in order to minimize
pressure drop per rotation effect.
[0046] The vanes 503 are slanted (i.e., positioned diagonally) with
respect to the vertical direction at an angle of 10 to 80 degrees,
such as 30 to 60 degrees, to direct the cathode exhaust 56 in the
azimuthal direction. At the base of each vane 503, an opening 564
through the plate 90 is provided instead of the common central
opening 64. The plurality of openings 564 provide the cathode
exhaust azimuthally from the assembly 501 into the radial passage
66 located below plate 90. While the assembly 501 is referred to as
turning vane assembly, it should be noted that the assembly 501
does not rotate or turn about its axis. The term "turning" refers
to the turning of the cathode exhaust stream 56 in the azimuthal
direction.
[0047] In an alternative configuration of the system of the first
embodiment shown in FIG. 10D, more than one turning vane assembly
501, 511 is provided. For example, the vanes 503 in assembly 501
move the cathode exhaust stream in opposite azimuthal direction
from that of the vanes 513 in assembly 511. In other words, the
vanes 503 may be slanted to the left to direct the cathode exhaust
counter-clockwise while vanes 513 may be slanted to the right to
direct the cathode exhaust clockwise. This creates a better
heat/temperature averaging throughout the hot box 28. The assembly
501 may be located inwardly or outwardly to assembly 511 with
respect to the central axis of the unit 10. There may be more than
two turning vane assemblies if desired, separated from each other
in the radial direction.
[0048] In another alternative configuration, the assemblies 501,
511 may have different vane 503, 513 lengths to create different
angular directions of cathode exhaust 56 flow for better
heat/temperature averaging throughout the hot box 28. The
assemblies 501, 511 may direct the cathode exhaust 56 in the same
direction or in opposite directions (i.e., one clockwise the other
counterclockwise, or both in the same clockwise or counterclockwise
direction) but at different radial angles.
[0049] In another configuration shown in FIG. 10E, one of the
assemblies 501, 503 (such as the inner assembly 503 for example) is
replaced with the central opening 64 (e.g., a bypass opening) shown
in FIG. 1. Thus, one portion of the cathode exhaust 56A moves
straight down into passage 66 while the remaining portion of the
cathode exhaust 56B is provided azimuthally into passage 66 by the
turning vane assembly.
[0050] If desired, an additional mixer similar in structure to the
turning vane assembly may be located in manifold 58. The additional
mixer is used to mix the cathode exhaust streams 56 exiting the
stacks 14 together into one exhaust stream and then distributes
back out at the bottom of the reformer 24. This may create even
better heat/temperature averaging throughout the hot box 28. The
additional mixer may be used together with the assembly 501 or
instead of the assembly 501.
[0051] In a second embodiment of the invention, spiral deflectors
601 (which may also be referred to as vanes or baffles) are
provided in the base of the unit (e.g., in the radial passage 66
between plates 90 and 139) to direct cathode exhaust flow to the
side (e.g., in the radial and/or azimuthal direction). The
direction should be consistent with reformer 24 tubes and pitched
fins 503 (if any) of the assembly 501. In other words, the
deflectors 601 may be used together with the assembly 501 of the
first embodiment or without the assembly 501 of the first
embodiment.
[0052] As shown in FIGS. 11A and 11B, the deflectors 601 comprise
plates, such as heat resistant metal or ceramic plates, which are
positioned in the passage 66 to deflect the cathode exhaust 56 in
the azimuthal and/or radial direction. The deflectors 601 may be
arranged in a spiral configuration to rotate the cathode exhaust 56
in the clockwise or counterclockwise direction. FIG. 11C
illustrates the use of the turning vane assembly 501 together with
the deflectors 601. The deflectors are arranged below the openings
564 in the assembly 501 to receive the cathode exhaust 56 from the
openings 564 and to provide an additional twist or swirl in the
azimuthal and/or radial direction to the cathode exhaust 56.
Alternatively, two or more rows of spiral deflectors may be
provided in the base (e.g., in passage 66), with the bottom row
directing the cathode exhaust 56 flow clockwise, and the top row
directing flow counterclockwise or vise versa. The deflectors 601
may have any suitable height in the base. Thus, the deflectors 601
may extend to the full height of the passage 66. Alternatively, the
deflectors 601 may extend to the partial height of the passage 66
and be fixed either to the top or bottom surface of the passage
66.
[0053] In a third embodiment of the invention, as shown in FIGS.
12A and 12B, respective vanes or deflectors 701A, 701B are provided
on the top of the heat shield 350 and/or on cover plate 368 of the
cathode recuperator 20 to direct the respective cathode feed (air
inlet flow) 44 and/or the cathode exhaust 56 in the azimuthal
and/or radial directions in the upper portions of the unit 10. The
vanes or deflectors 701A, 701B may extend in the same or different
directions from each other and may extend either in azimuthal or
radial directions. For example, vanes 701A may point in a clockwise
azimuthal direction while vanes 701B may point in the
counterclockwise azimuthal direction (or vice versa). The vanes or
deflectors 701A, 701B may comprise reinforcing ribs which protrude
from the respective heat shield 350 or cover plate 368. While
straight vanes or deflectors are shown, it should be understood
that the vanes or deflectors may be curved (e.g., spiral shaped).
The vanes or deflectors may be used in the reformer header to
direct flow to the side.
[0054] In a fourth embodiment of the invention, the fins or ribs in
one or more of the heat exchangers are pitched (e.g., extend in a
diagonal or helical direction) rather than comprising corrugated or
serpentine fins which extend in the vertical direction as shown in
FIGS. 1 and 3C. The fins or ribs of the fourth embodiment may
comprise individual fins or they may comprise a corrugated or
serpentine sheet which is arranged to provide a pitched fin
configuration.
[0055] For example, as shown in FIG. 13A, the outer fins 362 on the
outer surface of the tube 366 are pitched. In other words, the fins
362 are spiraling and are arranged diagonally with respect to the
vertical orientation. The pitched fins may be used on one or both
surfaces of the cathode recuperator 20 tube 366. If both surfaces
use pitched fins, the inside fin 364 pitch should be opposite to
the outside fin 362 pitch (e.g., if fins 362 are tilted to the
right, then fins 364 should be tilted to the left). The pitch for
the cathode exhaust should be in the same direction as the pitch of
the reformer 24 tubes 282 shown in FIG. 3A. Alternatively, the
pitched fins may be located on one or both surfaces of the anode
recuperator 22 and/or of the anode cooler 26. If both surfaces use
pitched fins, the inside pitch should be opposite to the outside
pitch. Thus, fins 300, 302, 312 and/or 312 may also be pitched.
[0056] Likewise, the fins inside and/or outside the ATO 38 may
pitched. If both surfaces use pitched fins, the inside pitch should
be opposite to the outside pitch. The fin backbone may could run at
an angle, such as at an angle of 30-60 degrees from the vertical
direction. For manufacturing purposes, the fins may need to be
installed in multiple segments of pitched fins. FIG. 13B shows four
segments 802A, 802B, 802C and 802D of pitched fins 801. The figure
shows the pitch with the same rotation for each horizontal segment.
It is also possible to reverse the fin rotation for alternate
segments, such that the fins 801 in odd numbered segments 802A, C
which circle the ATO 38 are slanted or tilted to the left and those
in even numbered segments 802B, D are slanted or tilted to the
right.
[0057] In an alternative configuration, vertical fins with pitched
transitions between segments may be used as shown in FIG. 13C. As
shown in FIG. 13C, vertical fin 803 segments 804 are separated by
pitched (i.e., slanted) fin 801 segments 802. The fin to fin
distance between adjacent fins 801 and between adjacent fins 803
may be the same. Alternatively, fin to fin distance between
adjacent fins 801 is at least 10% greater, such as at least 50%
greater, for example between 2 and 10 times greater than the
distance between adjacent fins 803 to induce flow with some
horizontal component. Alternatively, instead of using segments, the
slanted fins 801 may be formed by welding a channel on one surface
of the inner or outer or both shells of the ATO 38 annulus. In
conjunction with any of the above, rotation or swirl may be
introduced by appropriately slanted baffles or deflectors in the
inlet cone to the ATO 38 annulus.
[0058] The pitched fins may be provided to the unit 10 using any
one of several different configurations or methods. In one
configuration, pitched (e.g., slanted) fins are individually
attached to the surface of the desired heat exchanger 20, 22, 26
and/or 38. Such fins may extend the entire height of the region of
the heat exchanger in which fins are located, as shown in FIG.
13A.
[0059] In another configuration, the pitched fins are provided in
narrow segments as shown in FIGS. 13B and 13C. The fins and/or fin
segments may be attached to the heat exchanger cylinders or shells
using any suitable methods, such as brazing. Alternatively, rather
than attaching fins or segment strips to cylindrical heat exchanger
walls, grooves may be formed in the heat exchanger walls by
machining or other methods to leave a plurality of pitched grooves
separated by pitched fins.
[0060] Alternatively, the segments or strips may be attached
without using brazing. As shown in FIG. 13D, the strips 812 have
heat exchanger fins 801 which are at a bias to the vertical
direction (i.e., are inclined with respect to the strip height and
length by 10-80 degrees, such as by 30 to 60 degrees) to result in
rotating flow. Because the strips are not brazed, they can be
flexed into a circle around the desired cylindrical heat exchanger
shell and/or be inserted between the heat exchanger cylindrical
shells If desired, the unit may have a hot zone with this type of
construction (where radiation heat transfer is more dominant) and a
colder zone where brazing is used and strips have fins which are
not biased or slanted. Alternatively, diffusion bonding, such as
oxide growth, may be used to create the rigid conduction path for
heat with the fins. Preferably, the strips 812 are relatively thin
(e.g., have a relatively small height and thickness) to allow easy
bending. The heat exchanger is formed by several rows of strips 812
arranged around the heat exchanger's inner or outer cylindrical
surface in the vertical direction, as shown in FIG. 13D.
[0061] In another configuration shown in FIG. 13E, the fins 811 are
not biased or slanted on each strip 822. Instead, the fins 811 are
arranged so that they extend in the strip's height direction (e.g.,
perpendicular to the strip length direction). For example, in this
configuration, the strip 822 shown in FIG. 13H is a straight
corrugated sheet metal strip, for ease of manufacturing. The strip
822 is wrapped in a helical fashion as shown in FIG. 13E around the
heat exchanger's inner or outer cylindrical surface. Sufficiently
thin material is desired to achieve the required pliability.
[0062] Thus, as shown in more detail in FIGS. 13F and 13G, the
strips 812 of FIG. 13D are arranged horizontally inside or outside
each cylinder, but the fins 801 are slanted in a diagonal direction
to provide swirl or spiral fluid flow. In contrast, as shown in
more detail in FIG. 13H, the strips 822 of FIG. 13E are arranged in
a helical or diagonal direction inside or outside each cylinder,
but on each strip 822, the fins 811 are arranged in the strip
height direction. Since the strips 822 are arranged in a helical
direction, the fins 811 are arranged in the same direction as fins
801 on the heat exchanger to provide the same effect for the fluid
spiral or swirl flow.
[0063] In the prior art configuration, as shown in FIGS. 4E, 5, 6,
7 and 8, the electrodes 210 in electrode sleeves 211 protrude
through clearance openings 372 in the top of the unit 10. In
another embodiment of the invention, the electrode connection
through the top of the unit 10 using sleeves and openings 372 may
be omitted. Instead, as shown in FIG. 14, a voltage lead jumper 900
electrically connects the tops of two adjacent vertical columns of
stacks 14 (the stacks 14 are shown in FIG. 4E). Thus, two adjacent
stack columns are electrically connected in series and are referred
to as a stack column pair. Therefore, if there are eight columns of
stacks 14 in the unit 10, then there are four jumpers 900, each
located in one of four pairs of stack columns. The electrical
outputs for each stack column pair may be located on the bottom of
the unit 10. Thus, one electrical output may be connected to the
first stack column and the other electrical output may be connected
to the second stack column of each stack column pair. The
electrical outputs may comprise current collection rods or other
current take off devices which extend through the bottom surface of
the unit 10 to a power conditioning module or device.
[0064] The jumper 900 may comprise a flexible, high temperature
resistant, electrically insulating sleeve 903. For example, the
sleeve 903 may comprise a plurality of hollow ceramic cylinders,
such as 10 to 30, for example 20 alumina cylinders which can move
with respect to adjacent cylinders to provide flexibility to the
sleeve 903. A high temperature metal or metal alloy strand rope
wire 901, such as an Inconel or other nickel alloy wire, is located
in the sleeve 903. Additional electrical insulation may be provided
over the wire 901 inside the sleeve. The wire 901 is electrically
connected on both ends to electrically conductive terminals, such
as steel or Inconel terminals 905 which can be bolted to the stacks
through bolt holes 907. The terminals 905 may be connected to the
wire 901 using Inconel or other connectors.
[0065] Each component or method of the first, second, third, fourth
or fifth embodiment may be used alone or in combination with any
one or more other components or methods of the remaining
embodiments. While the first through fourth embodiments for
introducing rotation or swirl to the fluid flows are illustrated
with respect to the unit 10 shown in FIG. 1, it should be
understood that the components and methods of any one or more of
the first through fourth embodiments may be used in a unit having a
different overall structure or method of operation than unit 10.
Likewise, the jumper 900 may be used in other fuel cell systems
with or without devices for introducing rotation or swirl to the
fluid flows.
[0066] The foregoing description of the invention has been
presented for purposes of illustration and description. It is not
intended to be exhaustive or to limit the invention to the precise
form disclosed, and modifications and variations are possible in
light of the above teachings or may be acquired from practice of
the invention. The description was chosen in order to explain the
principles of the invention and its practical application. It is
intended that the scope of the invention be defined by the claims
appended hereto, and their equivalents.
* * * * *