Patent Publication Number: US-9837670-B2

Title: Methods and systems for fuel cell stack sintering and conditioning

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 13/768,307 filed on Feb. 15, 2013, now U.S. Pat. No. 9,065,127, which claims the benefit of priority of U.S. Provisional Patent Application No. 61/600,171 filed Feb. 17, 2012, entitled “Methods And Systems For Fuel Cell Stack Sintering And Conditioning”, the entire contents of which are incorporated by reference herein. 
    
    
     FIELD 
     The present application is directed to fuel cell components and fuel cell sintering and condition methods and systems. 
     BACKGROUND 
     A single planar solid oxide fuel cell (SOFC) may consist of a solid electrolyte which has high oxygen ion conductivity, such as yttria stabilized zirconia (YSZ); a cathode material such as strontium-doped lanthanum manganite on one side of the electrolyte, which may be in contact with an oxidizing flow stream such as air; an anode material such as a cermet of nickel and YSZ on the opposing side of the electrolyte, which may be in contact with a fuel flow stream containing hydrogen, carbon monoxide, a gaseous hydrocarbon fuel. The flow channels containing electrically conductive interconnect plates are located on the exposed sides of the anode and cathode to provide the electrical connection between adjacent cells, and provide flow paths for the reactant (e.g., fuel and air) flow streams to contact the anode and cathode. Fuel cells may be combined into units called “stacks” in which the fuel cells may be electrically connected in series and separated by electrically conductive interconnects, such as gas separator plates which may function as interconnects. Glass seals are located between each cell and adjacent interconnects in the stack to keep the stack together and to keep fuel and air flows separate. 
     Fuel cells may be combined to form a stack in a linear array (configured horizontally or vertically) in which the component fuel cells may be electrically connected in series to obtain a higher voltage (as compared to the voltage output of a single cell). A fuel cell stack may contain conductive end plates on its ends. A generalization of a fuel cell stack may be the so-called fuel cell segment or column, which may contain one or more fuel cell stacks connected in series (e.g., where the end plate of one stack is connected electrically to an end plate of the next stack). A fuel cell segment or column may contain electrical leads which output the direct current from the segment or column to a power conditioning system. A fuel cell system may include one or more fuel cell columns, each of which may contain one or more fuel cell stacks, such as solid oxide fuel cell stacks. 
     SUMMARY 
     The embodiments of the invention provide a system and method for sintering and conditioning fuel cell stacks. An embodiment provides channel guides for fuel cell sintering and conditioning. Another embodiment provides channel guides with ceramic rods for fuel cell sintering and conditioning. A further embodiment provides baffles and internal compression systems for fuel cell sintering and conditioning. An additional embodiment provides a fuel cell column cartridge assembly for fuel cell sintering and conditioning. Further embodiments provide methods for sintering and conditioning fuel cells at the system level. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a perspective view of channel guide rails according to an embodiment. 
         FIG. 2  illustrates a perspective view of channel guide rails with ceramic rods according to an embodiment. 
         FIG. 3A  illustrates a perspective view of a manifold base according to an embodiment. 
         FIG. 3B  illustrates a perspective view of a spacer manifold according to an embodiment. 
         FIG. 4A  illustrates a side view of an assembled channel guide according to an embodiment. 
         FIG. 4B  illustrates a front view of an assembled channel guide according to an embodiment. 
         FIG. 5  illustrates a front view of an assembled channel guide containing a fuel cell stack column and fuel manifolds according to an embodiment. 
         FIG. 6  illustrates a front view of an assembled channel guide containing a column of fuel cell stacks, fuel manifolds, and an internal compression system according to an embodiment. 
         FIG. 7  illustrates a perspective view of a column of fuel cell stacks and fuel manifolds with plate shaped side baffles according to an embodiment. 
         FIG. 8A  illustrates a side view of an assembled channel guide containing a column of fuel cell stacks and fuel manifolds with plate shaped side baffles according to an embodiment. 
         FIG. 8B  illustrates a front view of an assembled channel guide containing a column of fuel cell stacks and fuel manifolds with plate shaped side baffles according to an embodiment. 
         FIG. 8C  illustrates a top view of an assembled channel guide containing a column of fuel cell stacks and fuel manifolds with plate shaped side baffles according to an embodiment. 
         FIG. 8D  illustrates a top view of an assembled channel guide containing a column of fuel cell stacks and fuel manifolds with plate shaped side baffles according to another embodiment. 
         FIG. 9A  illustrates a side view of an assembled channel guide containing a column of fuel cell stacks and fuel manifolds coupled to fuel bellows with plate shaped side baffles according to an embodiment. 
         FIG. 9B  illustrates a side view of an assembled channel guide containing a column of fuel cell stacks and fuel manifolds coupled to fuel bellows with plate shaped side baffles according to another embodiment. 
         FIG. 9C  illustrates a side view of an assembled channel guide containing a column of fuel cell stacks and fuel manifolds coupled to fuel bellows with plate shaped side baffles according to a third embodiment. 
         FIG. 10A  illustrates a perspective view of a fuel cell column cartridge base according to an embodiment. 
         FIG. 10B  illustrates a perspective view of a fuel cell column cartridge plate according to an embodiment. 
         FIGS. 11A-11C  illustrate front views of fuel cell column cartridge assemblies according to various embodiments. 
         FIGS. 12A-12B  illustrate top views of a fuel cell column cartridge assembly system according to various embodiments. 
         FIG. 13  illustrates a front view of a fuel cell column cartridge assembly system according to an embodiment. 
         FIG. 14  illustrates a side view of a fuel cell column cartridge assembly system according to an embodiment. 
         FIG. 15  illustrates a perspective view of a hot box assembly according to an embodiment. 
         FIG. 16  illustrates a perspective view of a closed hot box assembly according to an embodiment. 
         FIG. 17A  illustrates a top perspective view of channel guide rails and an air bucket according to an embodiment. 
         FIG. 17B  illustrates a bottom perspective view of channel guide rails and an air bucket according to an embodiment. 
         FIG. 17C  illustrates a perspective view of an air bucket according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments of the invention illustrate systems and methods for sintering and conditioning fuel cell stacks. An embodiment provides channel guides for fuel cell sintering and conditioning. Additional embodiments provide channel guides with ceramic rods for fuel cell sintering and conditioning. Additional embodiments provide baffles and internal compression systems for fuel cell sintering and conditioning. Additional embodiments provide a fuel cell column cartridge assembly for fuel cell sintering and conditioning. Additional embodiments provide methods for sintering and conditioning fuel cells at the system level. 
     For purposes of this application “sintering” includes processes for heating, melting, and/or reflowing glass or glass-ceramic seal precursor material(s), such as glass or glass-ceramic forming powders and/or glass or glass-ceramic layers in the stack to form the glass or glass-ceramic seals between a fuel cell and two adjacent interconnects in the stack. Sintering may be performed at temperatures greater than 600 degrees Celsius, such as 600-1000 degrees Celsius, including 700-800 degrees Celsius, 800-900 degrees Celsius, 700-900 degrees Celsius, 900-950 degrees Celsius, and/or 950-1000 degrees Celsius. “Conditioning” includes processes for reducing a metal oxide (e.g., nickel oxide) in an anode electrode to a metal (e.g., nickel) in a cermet electrode (e.g., Ni-zirconia electrode, such as Ni—YSZ and/or Ni-scandia stabilized zirconia electrode, or Ni-doped ceria (e.g., scandia doped ceria) anode) and/or heating the stack during performance characterization/testing. Conditioning may be performed at temperatures from 750-900 degrees Celsius, such as 800-850 degrees Celsius, and may be performed with fuel and air flowing to respective cell anodes and cathodes. The sintering and conditioning processes may be conducted independently, in succession, or in any order. Preferably, the sintering and conditioning is performed on a fuel cell (e.g., SOFC) stack which is supported on the same support structure during both sintering and conditioning. These steps may be performed in the fuel cell system hot box or in a different location. A hot box may be a thermally insulated container in which the fuel cell stack(s) may be located. Additionally, the sintering and/or conditioning processes may be optional and not required for any given fuel cell stack. 
     Preferably, the sintering and the conditioning of the fuel cell stack are performed during the same thermal cycle. As used herein, “performing a process during the same thermal cycle” means the process is performed without cooling back to room temperature. Preferably, the sintering and the conditioning of the fuel cell stack are performed during the same thermal cycle (i.e., without cooling the fuel cell stack to room temperature between sintering and conditioning) while the fuel cell stack is located on and/or in the same support structure. The support structure may include a temporary base pate which supports the stack during sintering and/or conditioning and which is removed from the stack before the stack is placed on a hot box base in the hot box for operation (i.e., electricity generation). Alternatively, the support structure may include a portion of or an entire hot box base which is placed in the hot box and supports the fuel cell stack during operation (i.e., electricity generation). 
       FIG. 1  illustrates channel guide rails  102  and  104  according to one embodiment. Channel guide rail  102  may be a mirror image of channel guide rail  104 . The channel guide rails  102  and  104  may be three sided assemblies with a series of holes  106  drilled laterally through two of the three sides. Additionally, the sides of the channel guide rails may be configured to create various cutouts  108  in each of the three sides. The cutouts  108  may be configured to accept fuel tree connections, air inputs, or other connection to be made to fuel cell stacks contained within the channel guide rails  102  and  104  as discussed further below. However, in an alternative embodiment in which internally manifolded for fuel and air fuel cell stack(s) may be contained within the channel guide rails  102  and  104 , cutouts  108  may not be necessary. The channel guide rails  102  and  104  may be designed to constrain the fuel cell stacks (e.g., one stack or plural stacks in a column) during the sintering cycle and/or conditioning cycle. In this manner the fuel cell stack may be sintered and conditioned during the same thermal cycle. In an embodiment, the channel guide rails  102  and  104  may be used to constrain the fuel cell stacks during the sintering cycle and may be removed prior to a conditioning cycle. In an alternative embodiment the channel guide rails  102  and  104  may be used to constrain the fuel cell stacks during the sintering and conditioning cycles and may be removed prior to installation in the power generation system (e.g., in the fuel cell power generation system hot box). In another alternative embodiment the channel guide rails  102  and  104  may be used to constrain the fuel cell stacks during the sintering and conditioning cycles and may remain with the fuel cell stacks at installation in the power generation system (e.g., used in the closed hot box during system operation to generate power). 
     Channel guide rails  102  and  104  may be comprised of any suitable ceramic materials, such as aluminum oxide Al 2 O 3  (i.e., alumina). The channel guide rails  102  and  104  may be substantially comprised of alumina, such as 97% alumina. Alternatively, the channel guide rails  102  and  104  may be comprised of less than 97% pure alumina, or more than 97% pure alumina, such as 97% to 98%, 98% to 99%, 99% to 99.5%, 99.5% to 100%, such as about 97%, about 98%, about 99%, or about 100%. Channel guide rails  102  and  104  comprised of alumina may not yield at high temperatures, such as 800-950 degrees Celsius. Channel guide rails  102  and  104  comprised of alumina may not short the fuel cell stacks because alumina is not electrically conductive. Alumina may lend itself to tight machining tolerances which may allow control over maximum stack tilt. In a 40 stack yield test, the result for channel guide rails  102  and  104  comprised of 97% pure alumina was 100%, prescribed maximum tilt was less than 0.5 mm, and there were no cracked cells. 
       FIG. 2  illustrates channel guide rails  102  and  104  with technical ceramic rods  202  according to another embodiment. The technical ceramic rods  202  may be coupled to the interior walls of the channel guide rails  102  and  104 . The technical ceramic rods  202  may be comprised of alumina, such as 97% pure alumina. Alternatively, the technical ceramic rods  202  may be comprised of less than 97% pure alumina, or more than 97% pure alumina, such as 97% to 98%, 98% to 99%, 99% to 99.5%, 99.5% to 100%, such as about 97%, about 98%, about 99%, or about 100%. In an embodiment, the technical ceramic rods  202  may be created from powder pressed to form the technical ceramic rods  202  while the channel guides rails  102  and  104  may be created from alumina cast ceramic. In the embodiment illustrated in  FIG. 2  the technical ceramic rods  202  may be disposed within the channel guides rails  102  and  104  adjacent to the vertical bar portions  209  which bound the cutouts  108  in the channel guide rails  102  and  104  so as to not overlap any of the cutouts  108  in each of the three sides. In an embodiment the channel guide rail  102  and  104  bar portions  209  may provide the outer support skeleton while the technical ceramic rods  202  may create rails that act as the mechanical fuel cell interface during sintering. 
       FIG. 3A  illustrates a manifold base  302  for use with the channel guide rails  102  and  104  described above with reference to  FIGS. 1 and 2 . The manifold base  302  may be comprised of any suitable ceramic, such as alumina such as 97% pure alumina. Alternatively, the manifold base  302  may be comprised of less than 97% pure alumina, or more than 97% pure alumina, such as 97% to 98%, 98% to 99%, 99% to 99.5%, 99.5% to 100%, such as about 97%, about 98%, about 99%, or about 100%. In an embodiment the manifold base  302  may include holes  304  which are gas interfaces which line up with internal fuel cell stack riser channels and allow gases (e.g., fuel inlet and exhaust flows) to pass between the manifold base  302  and the fuel cell stack riser channels or bellows to be described below. In an embodiment, the manifold base  302  may include channels  306  (e.g., grooves) on the upper surface of the manifold base  302 . The manifold base  302  may be configured to support both the channel guide rails  102  and  104  as well as fuel cell stacks placed on top of the manifold base  302 , as will be described below. 
       FIG. 3B  illustrates an optional spacer manifold  308  for use with the channel guide rails  102  and  104  described above with reference to  FIGS. 1 and 2 . The spacer manifold  308  may be comprised of any suitable ceramic, such as alumina such as 97% pure alumina. Alternatively, the spacer manifold  308  may be comprised of less than 97% pure alumina, or more than 97% pure alumina, such as 97% to 98%, 98% to 99%, 99% to 99.5%, 99.5% to 100%, such as about 97%, about 98%, about 99%, or about 100%. In an embodiment, the spacer manifold  308  may include channels  312  (e.g., grooves) on the upper surface of the spacer manifold  308  and channels  314  (e.g., grooves) in the lower surface of the spacer manifold  308 . In an embodiment, the spacer manifold  308  may include gas interface openings  310  which pass through the spacer manifold  308  and line up with internal fuel cell stack riser channels. In an optional embodiment, the spacer manifold  308  may be configured to act as a separator between multiple stacks of fuel cells within the channel guide rails  102  and  104 . 
       FIGS. 4A and 4B  illustrate views of an assembled channel guide  400  according to an embodiment.  FIG. 4A  illustrates a side view of the channel guide  400  and  FIG. 4B  illustrates a front view of the channel guide  400 . The channel guide  400  may be comprised of the channel guide rails  102  and  104  as described above with reference to  FIG. 1 . The channel guide rails  102  and  104  may be placed on top of the manifold base  302 . Ceramic bolts or tie rods  402  may be used to clamp the channel guide rails  102  and  104  together. The ceramic bolt or tie rod  402  may have threading along a shaft  404  which may be passed through the holes  106  in the channel guide rails  102  and  104 . A ceramic nut  406  may be coupled to the ceramic bolt or tie rod  402  and the ceramic nut  406  may be tightened on the ceramic bolt or tie rod  402  may to clamp the channel guide rail  102  and  104  together on the manifold base  302  to form the channel guide  400 . The ceramic bolt or tie rod  402  and the ceramic nut  406  may be comprised of any suitable ceramic, such as alumina such as 97% pure alumina. Alternatively, the ceramic bolt or tie rod  402  and the ceramic nut  406  may be comprised of less than 97% pure alumina, or more than 97% pure alumina, such as 97% to 98%, 98% to 99%, 99% to 99.5%, 99.5% to 100%, such as about 97%, about 98%, about 99%, or about 100%. In alternative embodiments the channel guide rails  102  and  104  may be coupled together by other coupling means, such as fasteners, clamps, brazing, etc. While both the bolt or tie rod  402  and the nut  406  are preferably made from ceramic material, in alternative embodiments the bolt or tie rod  402  and the nut  406  may be made from metals, such as tungsten. 
       FIG. 5  illustrates a front view of an assembled channel guide  500 , similar to channel guide  400  described above with reference to  FIGS. 4A and 4B  with the addition of fuel cell stack(s)  502  and optional fuel manifolds  504  placed between adjacent stacks within the channel guide  500 . The fuel manifolds  504  may include protruding fuel feed/return assemblies configured to input fuel into a feed port  504 A and export fuel from an exhaust port  504 B. The fuel manifolds  504  may be similar to those described in U.S. patent application Ser. No. 11/656,563 filed on Jan. 23, 2007 and published as U.S. Patent Publication No. 2007/0196704 A1, herein incorporated by reference in its entirety. The fuel manifolds  504  may be used in the hot box of the assembled power generation system. The fuel manifolds  504  may separate adjacent fuel cell stack(s)  502  and provide fuel into fuel cell stacks located above and below the fuel manifolds  504 . In an embodiment, the channel guide  500  may be suitable for sintering any number of fuel cell stack(s)  502 , such as 1-10 fuel cell stack(s)  502  containing at total of 25-250 cells, or any number in between, such as 100-150 fuel cells and adjacent interconnects in 2-4 stacks, at a temperature greater than 900 degrees Celsius (e.g., 950-1000 degrees Celsius) in air or inert (e.g., N 2 ) ambient. Channel guide rails  102  and  104  may prevent stack tilting and shifting when seals melt during sintering. 
       FIG. 6  illustrates a front view of an assembled channel guide  600 , similar to channel guide  500  described above with reference to  FIG. 5  with the addition of an internal compression system  602 . While illustrated as a leaf spring system, the internal compression system  602  may utilize any type of internal compression, such as a ceramic leaf spring system, coil springs, torsion springs, volute springs, pistons, air cylinders, fluid cylinders, rod shaped spacers, etc. The internal compression system  602  may be used to apply a compressive load to the fuel cell stack(s)  502  during sintering and conditioning of the fuel cell stack. The internal compression system  602  may comprise the system described in U.S. application Ser. No. 12/892,582 filed on Sep. 28, 2010, herein incorporated by reference in its entirety. The application of internal compression to the fuel cell stack(s)  502  during the sintering and/or conditioning cycle may enable flexibility in the sintering and condition cycles, such as by allowing the use of a continuous furnace or simplified batch furnace. Additionally, the use of internal compression may enable the channel guide  600  to be laid on its side in a furnace, such as on a moving conveyor in the furnace, during the sintering and conditioning cycles. In an embodiment, the internal compression system  602  may be added to the assembled channel guide  600  prior to sintering and conditioning to compress the fuel cell stack(s)  502 . In an embodiment the internal compression system  602  may be used to compress the fuel cell stack(s)  502  during the sintering cycle and may be removed prior to a conditioning cycle. In an alternative embodiment, the internal compression system  602  may be used to constrain the fuel cell stack(s)  502  during the sintering and conditioning cycles and may be removed prior to installation in the power generation system. In another alternative embodiment, the internal compression system  602  may be used to constrain the fuel cell stack(s)  502  during the sintering and conditioning cycles and may remain with the fuel cell stack(s)  502  after installation in the hot box of a power generation system and may be used during the power generation operations of the power generation system. 
       FIG. 7  illustrates a column of fuel cell stack(s)  502  and fuel manifolds  504  with plate shaped side baffles  702  according to an embodiment. Exemplary side baffles  702  are described in U.S. application Ser. No. 12/892,582 noted above. The side baffles  702  may place a compressive load upon the fuel cell stack(s)  502  and may direct the cathode feed flow stream, such as air or another oxidizer to the fuel cell stack(s)  502  in the hot box during power generation system operation. The side baffles  702  may be comprised of high temperature material such as alumina, ceramic matrix composite, or other suitable ceramic. The side baffles  702  may have cutouts  704  for mating two side baffles  702  together. A bow tie shaped ceramic insert  706 , narrower at the middle portion and wider at the ends may be placed in the cutouts  704  to join two side baffles  702 . A top piece  708  and bottom piece  714  may join the side baffles  702  together as one unit enclosing the fuel cell stack(s)  502  and fuel manifolds  504 . The top piece  708  may have a cutout  710  similar to the cutouts  704  in the side baffles  702 . The bottom piece  714  may have a cutout  716  similar to the cutouts  704  in the side baffles  702 . A bow tie shaped ceramic insert  706  may join the top piece  708  and the bottom piece  714 , respectively, to the side baffles  702 . The top piece may include a hole  712  to allow a tie rod or another device to apply additional external compression to the fuel cell stack(s)  502  if needed. In an embodiment, an internal compression system  602  as described above may be placed below the top piece  708  within the side baffles  702  to provide internal compression to the fuel cell stack(s)  502 . In an embodiment, the internal compression system  602  may be added to the assembled channel guide  600  prior to sintering and conditioning to compress the fuel cell stack(s)  502 . In an embodiment, the side baffles  702  and the internal compression system  602  may be used to compress the fuel cell stack(s)  502  during the sintering cycle and may be removed prior to a conditioning cycle. In an alternative embodiment, the side baffles  702  and the internal compression system  602  may be used to constrain the fuel cell stack(s)  502  during the sintering and conditioning cycles and may be removed prior to installation in the hot box of power generation system. In another alternative embodiment, the side baffles  702  and the internal compression system  602  may be used to constrain the fuel cell stack(s)  502  during the sintering and conditioning cycles and may remain with the fuel cell stack(s)  502  after installation in the hot box of the power generation system, and may be used during power generation operations of the power generation system. 
       FIGS. 8A, 8B, 8C , illustrate views of an assembled channel guide  800  combined with a column of fuel cell stack(s)  502 , fuel manifolds  504 , compression system  602 , and plate shaped side baffles  702  according to an embodiment. Channel guide  800  is similar to channel guide  600  described above with reference to  FIG. 6  with the addition of side baffles  702  and bow tie shaped ceramic inserts  706  as described above with reference to  FIG. 7 .  FIG. 8A  illustrates a side view of the channel guide  800 . The channel guide rails  102  and  104  encompass (e.g., enclose and/or surround) the side baffles  702 , fuel cell stack(s)  502 , and fuel manifolds  504 , all of which are placed on top of the manifold base  302 . In an embodiment, internal compression may be provided by internal compression system  602  disposed within the side baffles  702  as described above with reference to  FIG. 7 .  FIG. 8B  illustrates a front view of the channel guide  800  where the edges of the fuel cell stack(s)  502  are exposed in the cutouts  108  between the vertical bar  209  portions of the channel guide rails  102  and  104 .  FIG. 8C  illustrates a top view of the channel guide  800 . 
       FIG. 8D  illustrates an alternative embodiment channel guide  800 A in which technical ceramic rods  202  are coupled to the vertical bar  209  portions of the channel guide rails  102  and  104  as described above with reference to  FIG. 2 . The technical ceramic rods  202  may provide the interface between the side baffles  702  and the channel guide rails  102  and  104 . 
       FIG. 9A  illustrates a side view of an assembled channel guide  900 A similar to channel guide  800  described above with reference to  FIGS. 8A-8C  with the addition of fuel connection  902  and fuel bellows  904 . Fuel connections  902  serve to connect the fuel manifolds  504  to the fuel bellows  904 . Fuel bellows  904  may be a series of flexible tubes configured to accommodate axial (e.g., vertical) thermal expansion of the fuel cell stack and each fuel bellow  904  may be tied to a fuel supply or a fuel exhaust to provide or exhaust fuel from the ports  504 A,  504 B of the fuel manifold  504  accordingly. The combination of fuel connections  902  and fuel bellows  904  may constitute a fuel tree for providing and recycling fuel to the fuel cell stack(s)  502 . While only one set of fuel bellows  904  is shown in  FIG. 9A  for providing fuel flow (or fuel exhaust) to the inlet or exhaust ports of the manifold  504  it should be understood that another set of bellows for collecting fuel exhaust (or providing inlet fuel) is located below the plane of the figure. Connections  902  may comprise caps which fit over openings in protruding port  504 A,  504 B portions of the fuel manifold  504 . In an alternative embodiment, flexible fuel tubes are used instead of the fuel bellows  904 . The flexibility of the tubes may also be attained by the use of an L-bend or additional service loops in the flexible tubes. 
       FIG. 9B  illustrates a side view of an assembled channel guide  900 B similar to channel guide  900 A described above with reference to  FIG. 9A  except that the individual fuel bellows  904  are replaced with common fuel bellows  906  interconnecting each of the fuel manifolds  504 . Exemplary fuel bellows are described in U.S. patent application Ser. No. 11/656,563 filed on Jan. 23, 2007 and published as U.S. Patent Publication No. 2007/0196704 A1 as noted above. The fuel bellows  906  may be flexible tubes configured to accommodate thermal expansion of the fuel cell stack. Preferably, the fuel bellows  906  are removed after sintering and/or conditioning if these steps are conducted outside the hot box of a power generation system. In the channel guide  900 B the upper most fuel connection  902  may also serve as an end cap to the fuel supply and exhaust return systems. The combination of fuel connections  902  and fuel bellows  906  may constitute a fuel tree for providing and recycling fuel to the fuel cell stack(s)  502 . While only one fuel bellow  906  is shown in  FIG. 9B  for providing fuel flow (or fuel exhaust) to the inlet or exhaust ports of the manifold  504  it should be understood that another bellows for collecting fuel exhaust (or providing inlet fuel) is located below the plane of the figure. 
       FIG. 9C  illustrates a side view of an assembled channel guide  900 C similar to channel guide  900 B described above with reference to  FIG. 9B  except that common fuel bellows  908  are installed directly between the fuel manifolds  504  without the use of fuel connections  902 . Fuel bellows  908  may be connected directly between the manifolds  504  and the ends of fuel bellows  908  may be configured with fluid connections  910  which may couple the fuel bellows  908  to the inlet and/or exhaust ports of the manifold  504 . The combination of fuel bellows  908  may constitute a fuel tree for providing and recycling fuel to the fuel cell stack(s)  502 . While only one fuel bellow  908  is shown in  FIG. 9C  for providing fuel flow (or fuel exhaust) to the inlet or exhaust ports of the manifold  504  it should be understood that another bellows for collecting fuel exhaust (or providing inlet fuel) is located below the plane of the figure. In an embodiment in which the fuel bellows  908  may be connected between the manifolds  504 , during conditioning an electrical insulating element may be required in the fuel bellows  908  to avoid shorting the fuel cell stack(s)  502 . 
       FIG. 10A  illustrates a fuel cell column cartridge base  1000  and  FIG. 10B  illustrates a fuel cell column cartridge plate  1002  according to an embodiment. The fuel cell column cartridge base  1000  and fuel cell column cartridge plate  1002  may enable a fuel cell column to be assembled and transported (e.g., into the hot box or into the sintering/conditioning furnace) in a pre-processed condition. The fuel cell column cartridge base  1000  and fuel cell column cartridge plate  1002  may contain multiple technological elements, such as mechanical compression, mechanical guides, mechanical constraints, voltage sensing, cathode gas (e.g., air) delivery, and anode gas (e.g., fuel) delivery. The fuel cell column cartridge base  1000  and fuel cell column cartridge plate  1002  may interface with the process furnace and may enable the production of a sintered/conditioned fuel cell column. The fuel cell column cartridge base  1000  and fuel cell column cartridge plate  1002  may be reusable in a mass production environment. The fuel cell column cartridge base  1000  and fuel cell column cartridge plate  1002  may enable the fuel cell columns to be built via automation. The fuel cell column cartridge base  1000  and fuel cell column cartridge plate  1002  may provide a method for securing and transporting a fuel cell column to facilitate less handling, improved component organization, provide a common interface for system components, and standardize interfaces for measurement equipment. 
       FIG. 10A  illustrates a fuel cell column cartridge base  1000  according to an embodiment. The fuel cell column cartridge base  1000  may be comprised of a base surface  1004  and an air bucket  1006 . The fuel cell column cartridge base  1000  may have an air input conduit  1008  to provide air from an external air source (e.g., an air blower) to the air manifold (e.g., air bucket)  1006 . The air bucket  1006  has an open surface  1007  facing the area where the fuel cell stack(s) will be positioned on the base  1002  inside the channel guide rails  102  and  104 . The fuel cell column cartridge base  1000  may have a fuel inlet conduit  1010  to provide fuel from an external fuel source to the fuel inlet coupling  1014 . A fuel exhaust conduit  1012  may receive fuel exhaust from the fuel exhaust coupling  1016  and pass fuel exhaust out of the fuel cell column cartridge base  1000  via fuel exhaust conduit  1012 . Conduits  1008 ,  1010 ,  1012  may have one end in the side of the base  1000  and another end in the top surface  1004 . While shown in a configuration in which conduit  1010  is above conduit  1012 , conduits  1010  and  1012  may be provided in any other configuration, such as side by side. Additionally, conduits  1008 ,  1010 , and  1012  may take any path through the fuel cell column cartridge base  1000 . The air bucket  1006  may contain a current and voltage measurement device  1026  configured to measure current and voltage along a linear array of current or voltage sources (e.g., the fuel cell stacks in the column or the interconnects in each stack). An exemplary current and voltage measurement device  1026  is described in U.S. Provisional Application No. 61/511,308 filed on Jul. 25, 2011, which is incorporated herein by reference in its entirety. The current and voltage measurement device  1026  may be comprised of two sensing probes  1034  on a carriage  1035 . The carriage  1035  may be driven up and down (e.g., along the height) along the side of the air bucket  1006  facing the fuel cell column via a drive screw  1032  driven by an electrical motor  1020  housed within the fuel cell column cartridge base  1000 . Signal carrying members  1028  and  1030  (e.g., cables or wires) may connect the sensing probes  1034  to the probe output wires  1022  and  1024 . The probe output wires  1022  and  1024  may enable remote sensing of the current and/or voltage external from the fuel cell column cartridge base  1000 . In an alternative embodiment, the measurement device  1026  may only measure voltage while current may be measured using a shunt outside the furnace hot zone. While shown as a rectangular surface, the fuel cell column cartridge base  1000  and base surface  1004  may be made in any shape, such as circular. In an embodiment, the fuel cell column cartridge base  1000  may be indexible by a robot and/or forklift. In this manner, the fuel cell column cartridge base  1000  may be indexible from a build area to a conditioning and/or sintering area, to a hot box, and/or to a post processing area where channel guide rails may be removed from the fuel cell stack(s). 
       FIG. 10B  illustrates a fuel cell column cartridge plate  1002  according to an embodiment. The fuel cell column cartridge plate  1002  may enable the fuel cell column to be built up and moved to the fuel cell column cartridge base  1000 . The fuel cell column cartridge plate  1002  may comprise a top surface  1036  and a cutout  1038 . The cutout  1038  may be configured to engage the air bucket  1006  of the fuel cell column cartridge base  1000  when the fuel cell column cartridge plate  1002  is placed on top of the fuel cell column cartridge base  1000 . The fuel cell column cartridge plate  1002  may have a fuel riser opening  1040  configured to connect to the fuel inlet coupling  1014  of the fuel cell column cartridge base  1000  and to a fuel bellow. The fuel cell column cartridge plate  1002  may have a fuel exhaust riser opening  1042  configured to connect to the fuel exhaust coupling  1016  of the fuel cell column cartridge base  1000  and to a fuel bellow. In an embodiment the fuel cell column cartridge plate  1002  may have tie rod pass through opening(s)  1044  for passing tie rods through the fuel cell column cartridge plate  1002 . 
       FIGS. 11A, 11B, and 11C  illustrate fuel cell column cartridge assemblies  1100 A,  1100 B, and  1100 C, respectively, according to various embodiments. A fuel cell column cartridge assembly,  1100 A,  1100 B, or  1100 C may be formed by coupling a fuel cell column to the fuel cell column cartridge plate  1002  as described above with reference to  FIG. 10B . In an embodiment the column cartridge plate  1002  may be placed on the fuel cell column cartridge base  1000  and the column cartridge plate  1002  and the fuel cell column cartridge base  1000  may be placed on a hot box base of a power generation system after sintering and conditioning the fuel cell column. In an alternative embodiment, the fuel cell column may be directly coupled to the fuel cell column base  1000  without the use of a fuel cell column cartridge plate  1002 . In a further embodiment, a fuel tree may be placed on the base plate and connected to the fuel cell column, such as by bellows connected to a fuel manifold of the fuel cell column. In an embodiment, the fuel cell column cartridge base  1000 , column cartridge plate  1002 , fuel tree, and fuel cell column may be enclosed on the hot box base with a hot box lid. In an alternative embodiment, the fuel tree may be removed from the fuel cell column after sintering and/or conditioning, and the fuel cell column cartridge base  100 , column cartridge plate  1002 , and fuel cell column may be placed on a hot box base of a power generation system. 
       FIG. 11A  illustrates a fuel cell column cartridge assembly  1100 A comprised of an assembled channel guide  900 B as described above with reference to  FIG. 9B  coupled to the fuel cell column cartridge plate  1002 . The assembled channel guide  900 B may be coupled to the fuel cell column cartridge plate  1002  via a tie bar system comprised of tie bars  1104  connected by a retaining member  1102  (e.g., a metal or ceramic cap or tie bar). Respective inlet and exhaust fuel bellows  906 A,  906 B may be coupled to the fuel riser  1040  and the fuel exhaust riser  1042 . 
       FIG. 11B  illustrates a fuel cell column cartridge assembly  1100 B similar to fuel cell column cartridge assembly  1100 A described above with reference to  FIG. 11A  except that tension is placed on the tie bar system via a cylinder  1108  attached to a tension member (e.g., tension plate)  1106  connected between the tie rods or bars  1104  below plate  1002 . The cylinder  1108  may be any type pneumatic cylinder, such as an air cylinder or oil cylinder. In another embodiment, the cylinder  1108  and tension member  1106  may be decoupled from the fuel cell column cartridge plate  1002 . In an alternative embodiment, the cylinder  1108  may be replaced by a spring which may exert force on the tension member  1106  thereby tensioning the tie bar system. 
       FIG. 11C  illustrates a fuel cell a fuel cell column cartridge assembly  1100 C in which an assembled channel guide similar to assembled channel guide  500  described above with reference to  FIG. 5  is coupled to the fuel cell column cartridge plate  1002 . No internal compression system is used, rather external compression is provided by a cylinder  1110 . The cylinder  1110  may be any type pneumatic cylinder, such as an air cylinder or oil cylinder and may be decoupled from the fuel cell column cartridge assembly  1100 C. The cylinder  1110  may apply pressure to the fuel cell stack(s)  502  through hole  712  in top piece  708 , discussed above with reference to  FIGS. 7, 8C, and 8D . In an alternative embodiment, the cylinder  1110  may be replaced by a spring which may apply pressure to the fuel cell stack(s)  502  through hole  712 . 
       FIGS. 12A, 12B, 13, and 14  illustrates different views of a fuel cell column cartridge assembly system  1200  according to an embodiment. The fuel cell column cartridge assembly system  1200  may be comprised of a fuel cell column cartridge assembly  1100 A described above with reference to  FIG. 11A , coupled to a fuel cell column cartridge base  1000  described above with reference to  FIG. 10A .  FIG. 12A  illustrates a top view of the fuel cell column cartridge assembly system  1200 . The fuel cell column cartridge assembly  1100 A may be placed on the fuel cell column cartridge base  1000  such that the opens side  1007  of the air bucket  1006  contacts the partially open back of the channel guide rail  104  to provide air into fuel cell stacks.  FIG. 12A  illustrates an embodiment in which the conduits  1010  and  1012  are vertically aligned, with conduit  1010  above conduit  1012 .  FIG. 12B  illustrates an alternative embodiment in which conduits  1010  and  1012  may be horizontally aligned. In an embodiment, conduit  1012  may take a non-linear path through the fuel cell column cartridge plate  1002 . In the various embodiments, conduits  1008 ,  1010 , and  1012  may take any path through the fuel cell column cartridge plate  1002 . 
       FIG. 13  illustrates a front view of the fuel cell column cartridge assembly system  1200 . The fuel cell column cartridge plate  1002  may be positioned on the fuel cell column cartridge base  1000  such that fuel inlet streams and fuel exhaust streams may pass through the riser opening  1040 ,  1042  in fuel cell column cartridge plate  1002  and to and from the fuel inlet and exhaust bellows  906 A and  906 B.  FIG. 14  illustrates a side view of the fuel cell column cartridge assembly system  1200  illustrating the positioning of the fuel cell column cartridge assembly  1100 A described above with reference to  FIGS. 11A and 11B , coupled to a fuel cell column cartridge base  1000 . 
       FIG. 15  illustrates a hot box assembly  1500  according to an embodiment. The hot box assembly  1500  may be populated with unsintered fuel cell stacks within assembled channel guides  1504 ,  1506 , and  1508  similar to assembled channel guide  600  described with reference to  FIG. 6 . The assembled channel guides  1504 ,  1506 , and  1508  may be placed upon a hot box base  1502 . A hot box base  1502  may be any structure in the hot box that supports one or more fuel cell stacks. Instead of processing each assembled channel guide  1504 ,  1506 ,  1508  and its respective fuel cell stacks separately on a subsystem level, the assembled channel guides  1504 ,  1506 , and  1508  may be inserted into the heating structure (e.g., a furnace) that facilitates stack sintering and conditioning as a group on the hot box base  1502 . Specialized gas supplies and stack compression mechanism may be provided before and/or after the sintering and/or conditioning process as described above. The assembled channel guides  1504 ,  1506 , and  1508  may be permanently attached to the fuel cell stack columns. The hot box base  1502  may provide fuel and air flow manifolds to the fuel cell stack columns. In an embodiment, the hot box base  1502  may comprise the fuel cell column cartridge plate  1000  and/or the fuel cell column cartridge plate  1002 . In an embodiment the hot box base  1502  with the permanently attached channel guides  1504 ,  1506 , and  1508  may be sintered and/or conditioned in a furnace. A benefit of the group sintering and conditioning on the hot box base  1502  may be that stacks and cells are sintered and conditioned together for uniformity, less handling may be required to assemble the overall power generation system, and the stacks and cells may still be accessible after the sintering and conditioning cycle. Also, an external heating mechanism may be used to attain the temperatures required for stack sintering and/or conditioning. In an embodiment, thermally inductive heating and/or microwave heating may be used to heat the metal interconnects to greater than 950 degrees Celsius while maintaining the temperature at the ceramic channel guides  1504 ,  1506 , and  1508  at less than 850 degrees Celsius. After sintering and conditioning further components (e.g., heat exchanger(s), fuel inlet tube(s), splitter(s), valve(s), etc) necessary for power generation may be added to the assembled channel guides  1504 ,  1506 , and  1508 , or optionally components (e.g., fuel bellows  906  and fuel caps  902 ) may be removed. After sintering and conditioning the hotbox assembly  1500  may be closed and insulated, as shown in  FIG. 16 . 
     In an embodiment, unsintered and/or unconditioned fuel cell stack(s)  502  may be placed on hot box base  1502  and the fuel cell stack(s)  502  may be placed in a heating structure that facilitates fuel cell stack(s)  502  sintering and/or conditioning, such as a furnace. The fuel cell stack(s)  502  may be sintered and/or conditioned in the heating structure. During conditioning (e.g., reduction of NiO to Ni in the fuel cell anodes) fuel (e.g., a reducing ambient) may be provided, such as hydrogen or hydrocarbon fuel, to the anode(s) of the fuel cell stack(s)  502  and air may be provided to the cathode(s) of the fuel cell stack(s)  502 . During sintering air or inert gas may be provided. In an embodiment, inductive or microwave heating may be used to increase the temperature of the fuel cell stack(s)  502  during sintering and/or conditioning. After sintering and conditioning of the fuel cell stack(s)  502  the hot box base  1502  and fuel cell stack(s)  502  may be removed from the heating and structure and a hot box lid may be placed on the hot box base. 
     In an alternative embodiment, the fuel cell column cartridge plate  1000  and/or the fuel cell column cartridge plate  1002  may be temporary structures different from the hot box base  1502 . The fuel cell column cartridge plate  1000  and/or the fuel cell column cartridge plate  1002  may be removed from the stack before the stack is placed on the hot box base. Alternatively, the fuel cell column cartridge plate  1000  and/or the fuel cell column cartridge plate  1002  may comprise a portion of a hot box base and may be attached to the rest of the hot box base  1502  after sintering and/or conditioning. 
       FIG. 16  illustrates a closed hot box assembly  1600  according to an embodiment. The closed hot box assembly  1600  may be populated with unsintered and unconditioned fuel cell stacks within assembled channel guides  1604 ,  1606 , and  1608 . The assembled channel guides  1604 ,  1606 , and  1608  may be permanently attached to the fuel cell stack columns. The assembled channel guides  1604 ,  1606 , and  1608  may be placed upon a hot box base  1502  and all necessary components, such as internal compression systems, fuel bellows, tie bars, and any additional power generation equipment (e.g., heat exchanger(s), fuel inlet tube(s), splitter(s), valve(s), etc) may be coupled to the assembled channel guides  1604 ,  1606 , and  1608 . The closed hot box assembly  1600  may be completed by the addition of a hot box shell  1602  placed over the assembled channel guides  1604 ,  1606 , and  1608  and coupled to the hot box base  1502 . The closed hot box assembly  1600  may be entirely closed up before the stacks are heated for sintering and/or conditioning. Temperature and gas supplies to the closed hot box assembly  1600  may then be manipulated to provide the appropriate environment for sintering and conditioning and anode reduction. In an embodiment, the sintering and/or conditioning inside the closed hot box assembly  1600  may be the initial operating step of a power generation system which includes the closed hot box assembly  1600  to generate electricity. In an embodiment, both sintering and conditioning may be performed inside the hot box assembly  1600 . In an alternative embodiment, only conditioning may be performed in the hot box assembly  1600 , while sintering may be performed in a furnace. 
       FIG. 17A  illustrates channel guide rails  1702  and  1704  positioned next to the air bucket  1006  according to an embodiment. Channel guide rails  1702  and  1704  may be similar to channel guide rails  102  and  104  discussed above, except that channel guide rails  1702  and  1704  may be configured to create larger cutouts  1706  which lack any vertical rods and are thus configured differently than cutouts  108  in channel guide rails  102  and  104 .  FIG. 17B  illustrates channel guide rails  1702  and  1704  positioned next to the air bucket  1006  shown from a bottom perspective view. In an embodiment, in the bottom of the air bucket  1006  an outlet opening  1708  may function to exhaust air from the air bucket  1006 .  FIG. 17C  illustrates the air bucket  1006  according to an embodiment. The air manifold or “bucket”  1006  may be configured to remove air from a fuel cell stack placed within the channel guide rails  1702  and  1704 . Air exhausted from the fuel cell stack may exit pass through cutout  1706  into an opening  1710  in the open surface  1007  of the air bucket  1006  and may pass through the air bucket  1006  to the outlet opening  1708  in the bottom surface of the air bucket  1006 . In an embodiment, the outlet opening  1708  may be coupled to conduit  1008  discussed above with reference to  FIG. 10A . The air bucket  1006  may be made from any material, such as preferably ceramics, such as alumina, such as 97% pure alumina. Alternatively, the air bucket  1006  may be comprised of less than 97% pure alumina, or more than 97% pure alumina, such as 97% to 98%, 98% to 99%, 99% to 99.5%, 99.5% to 100%, such as about 97%, about 98%, about 99%, or about 100%. 
     The preceding description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the described embodiment. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the disclosure. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed herein. 
     U.S. application Ser. No. 11/656,563 filed on Jan. 23, 2007 and published as U.S. Patent Publication No. 2007/0196704 A1, U.S. application Ser. No. 12/892,582 filed on Sep. 28, 2010, and U.S. Provisional Application No. 61/511,308 filed on Jul. 25, 2011, are incorporated herein by reference in their entirety.