JP2019505975A - Reformer including an extruded guide wall perpendicular to the flow path - Google Patents

Abstract

A guide wall for a serpentine channel (15) through which steam passes during conversion to syngas used in the fuel cell (2) to produce the reformer (6) in the fuel cell system (1) ( The profile (31) with 17) is extruded.
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a reformer in a fuel cell system.

  When using a liquid fuel for a power generation fuel cell, hydrogen for the fuel cell is produced by converting the liquid fuel into a synthesis gas, also called a syngas containing a large amount of gaseous hydrogen. An example of a liquid fuel is a mixture of methanol and water, but other liquid fuels, particularly other alcohols including ethanol, can also be used. For conversion, a syngas for the fuel cell is provided by evaporating liquid fuel in the evaporator and catalytic conversion in the reformer. In order to reach the required conversion temperature of 250-300 ° C., the reformer must be heated, for example by exhaust gas from a burner. The temperature of the burner gas is typically 350-400 ° C.

  A general example of a reformer is disclosed in Patent Document of England (see, for example, Patent Document 1). For proper heat transfer between the hot exhaust gas and the reformer, the reformer is inserted into a rolled corrugated metal or extruded metal radiator core and brazed to it. This approach is similar to the heat exchanger field. In this field, the general teaching is to conduct heat transfer from the media flowing along the fins by extruding the tubes and brazing the thin fins to the outer wall of the tubes. Inside such an extrusion tube, the liquid flows in the same direction as the extrusion direction. This is in accordance with traditional ideas in the technical field of heat exchangers. From the general art of heat exchangers it is known to use a cladding or powder spray on an extruded aluminum core. In the case of an example disclosed in another patent document (see, for example, Patent Document 2), spray application of powder brazing agent is used to braze the corrugated fins onto the extruded aluminum core of the heat exchanger. Another patent document discloses that the corrugated fin is clad before brazing (see, for example, Patent Document 3).

  In addition, the cylinder body of the extrusion reformer module disclosed in another patent document has a plurality of channels along the flow direction, which reflects the traditional idea of extrusion ( For example, see Patent Document 4.)

  While extrusion is a commonly used method for conduits where the fluid flow is along a direction having a constant cross section, extrusion has a more complex structure where the flow is not along a direction having a constant cross section. It is clearly not an advantageous method to use for the reformer.

  High temperature proton exchange membrane fuel cells, also called high temperature proton electrolyte membrane (HTPEM) fuel cells, are advantageous in that they can withstand relatively high CO concentrations and thus do not require a PrOX reactor between the reformer and the fuel cell stack. is there. For this reason, a simple, lightweight and inexpensive reformer can be used. Such a reformer minimizes the overall size and weight of the system, for example in line with the objective of providing a compact fuel cell system for the automotive industry. However, to be efficient while being small in size, the reformer requires a sufficiently long reaction path. This reaction path is typically significantly longer than the outer dimensions of the small reformer. To combine the low weight, small dimensions, and long reaction path, the reaction path is potentially formed as a serpentine path so that the reactants follow a zigzag curve through the reformer. Must.

  Such a meandering flow path is also known from a microreactor as disclosed in a certain patent document (for example, see Patent Document 5). In this case, the manufacturing method is disclosed as milling or molding. Typically, milling is performed to a predetermined depth of the solid block, the base remains as a solid plate, and the structure extends from the base. Milling or molding is a common method proposed for serpentine structures in fuel cell technology. An example is the manufacture of a solid bipolar plate with a serpentine channel as disclosed in another patent document (see, for example, patent document 6).

  From these disclosures in various technical fields, extrusion is a commonly used method useful for manufacturing tubes with invariant profiles along the tube axis, in the same direction as the extrusion direction. A method in which a fluid flow flows along a direction having an invariant cross-section, whereas milling is due to a more complex profile where the flow does not follow the extrusion direction, for example along a serpentine channel. It seems to be a typical method.

  Milling is versatile and easy to adjust for complex profiles. However, milling has the disadvantage of being relatively slow and thus not optimal for mass production. Milling also implies that a large amount of material waste is generated. This is because the material removed by milling from a block, such as an aluminum block, is not useful and must be discarded. Molding is more suitable for mass production, but not for a closed structure that surrounds the volume. For these reasons, molding imposes restrictions on the manufacturing method and requires additional assembly steps. Molding also requires different molds for different sizes, which increases manufacturing costs.

  Accordingly, it is desirable to find another method of manufacturing a fuel cell reformer with a complex shape, particularly a serpentine channel.

U.S. Pat. No. 7,976,787 European Patent No. 595601 EP 417894 specification China Utility Model No. 202517022 Specification US Pat. No. 8,574,500 International Publication No. 2009/010067

  Accordingly, it is an object of the present invention to provide an improvement in technology. In particular, it is an object to provide an improved method of manufacturing a fuel reformer in a fuel cell system, especially because of the complex shape deviating from a straight tube. One significant form for a reformer is a serpentine flow path through the reformer, with the goal of finding an improved manufacturing method. This object is solved by the following manufacturing method of the fuel cell system.

  During manufacture, the metal profile is cut perpendicular to the profile to provide the metal profile by extrusion and to provide a reformer housing. The catalyst is provided inside the reformer and the volume is closed by covering the cut end with a wall element. An evaporator is connected to one end, and a fuel cell is connected to the opposite end. In preparation for heating the reformer with hot gas, a thin heat conducting layer is optionally provided on the outer surface.

  In more detail, the following advantageous forms are provided. The extruded profile includes two extruded opposing walls facing each other with a predetermined distance between the walls and a predetermined volume between the walls. This volume is ultimately used for the conversion of steam to syngas. Each of the two walls is an integral group of extruded spaced apart guide walls extending from each of the two walls toward the opposite wall by a distance greater than half the distance between the walls. Including. For example, the length of the guide wall is 60% to 90% of the distance between the opposing walls. The guide wall forms a comb-like structure on each of the two walls. The two comb structures face each other and are offset from each other in the lateral direction so as to mesh with each other and form a serpentine channel in a direction perpendicular to the extrusion direction. Thus, the gas cannot travel along a straight line across the volume in a direction perpendicular to the extrusion direction, but must follow a meandering elongated path.

  For example, a profile provides a box with a square cross-sectional profile by extruding two opposing walls as a box profile joined by additional walls, typically two additional walls facing each other. Alternatively, the profile is provided as two extruded halves of the box profile. These halves are extruded and then assembled into box profiles. For example, each half includes only one of two opposing walls and one group of mutually spaced guide walls extending from one of the walls, and the assembly is on opposite sides. A guide wall is provided to form a serpentine flow path.

  For example, when the guide walls are provided at equal intervals in a certain period and are offset asymmetrically in the direction perpendicular to the extrusion direction by a quarter period in the half profile, The two halves can be provided by extruding a single profile and then cutting the profile into two equal length sections. During assembly, one section is provided in the extrusion direction and the other half is rotated 180 degrees around the extrusion direction and 180 degrees around a line perpendicular to the extrusion direction. Due to the offset of a quarter period, the guide walls mesh with each other with half the period between the meshing guide walls extending opposite to each other.

  An example of a useful material is aluminum or an aluminum alloy, such as a wrought alloy. The thermal conductivity is relatively high because it conducts heat from outside the profile into the volume inside the reformer. This is because this volume will be used for the catalytic conversion of fuel vapor to syngas, which typically requires temperatures above about 250 ° C. For example, to withstand burner gases at temperatures above 300 degrees, the alloy is advantageously a 5000 series aluminum alloy containing aluminum and magnesium, or a 6000 series aluminum alloy containing aluminum, magnesium and silicon. .

  A steam inlet and a syngas outlet are provided in the profile at opposite ends of the serpentine steam channel to allow the steam to flow into the volume and the syngas to flow out of the volume. For example, holes are formed in the metal profile and conduits are attached to these holes. The conduit is later used to fluidly connect the liquid fuel evaporator to the vapor inlet and the fuel cell to the syngas outlet.

  Depending on the desired width of the reformer, the profile is cut perpendicular to the extrusion direction and also perpendicular to the serpentine channel. Extrusion allows a single extrusion profile to provide portions for multiple reformer housings. Each of these parts is cut from the extruded profile at a length suitable for the purpose. For example, one cut piece of profile is short and can be used for a reformer connected to a single fuel cell stack, and another cut piece is long and syngas is applied to multiple fuel cell stacks. It can be used for the reformer provided.

  Thus, it can be seen that extrusion not only simplifies the production of the reformer, but is also flexible in terms of size adjustment. In the case of molding, such flexibility is not given. This is because each size change requires a different molding type. The work associated with small and large reformers is not much different when using extrusion. This is also in stark contrast to the case where milling is used in manufacturing. Although milling is generally versatile, the larger the reformer, the more time it takes to perform the milling process, and the milling that is performed to a very deep depth is mechanical in terms of accuracy and stability. It is difficult to. For these reasons, milling is not suitable for large reformers, in addition to the disadvantage that a large amount of milling material is discarded. Overall, extrusion to produce a reformer is advantageous in several aspects.

  A catalyst material, such as catalyst pellets, is inserted into the volume. The volume is then closed by a wall element that provides a closed reformer housing for catalytic conversion of fuel vapor to syngas in the volume inside the housing.

  In operation, a suitable temperature for the catalytic conversion process inside the housing, typically 250-300 degrees when the fuel is a mixture of methanol and water, and higher alcohol or diesel is used as the fuel In some cases, the reformer housing is heated to provide a higher temperature.

  Although electrical heating is possible to regulate the temperature in the reformer, a useful way to provide this necessary heat is to direct hot gas along the outside of the metal profile, The metal introduces heat into the reformer volume. A thin layer of parallel metal is brazed to the outside of the housing for efficient heat transfer from the hot gas. For example, to provide such a thin layer, a thin sheet material is folded into a corrugated structure and brazed on its surface before brazing to the outside of the reformer housing. Optionally, the thin layer is provided on at least two sides of the profile, for example on opposite sides. In order to obtain a high heat transfer effect, it is advantageous if one or more of the largest sides of the profile are covered with a thin layer. For example, if the reformer volume has a rectangular cross section with two long sides and two short sides, the thin layer is provided on the long side.

  In order to guide the hot gas along the lamina, the reformer housing is surrounded by a casing. The casing has a burner gas inlet at one end of the parallel metal lamina and a burner gas outlet at the opposite end so that the gas is guided along the lamina surface. The burner gas inlet is then fluidly connected to the burner.

  As long as the profiled material is extruded, as long as the profiled profile has an invariable cross section along the extrusion direction of the profiled material, the wall can be easily made with various cross-sectional shapes, including straight or bent shapes, for example wave shapes Can be formed. The shape of the guide wall affects the flow rates of the steam and syngas that pass through the serpentine channel perpendicular to the extrusion direction. In addition, the guide wall optionally comprises vanes to create turbulence and mixing and to guide the gas toward the center of the serpentine channel for optimization of the catalytic conversion process. For example, in cross-section, the guide wall includes a straight or curved stem that extends from one of the two opposing walls to the other. The stem then includes vanes extending from the stem, eg, vanes extending laterally from the stem, to provide obstructions and corresponding turbulence along the serpentine steam flow path. When the stem is provided with a plurality of blades, the shape of the fish bone is one option when viewed in cross section.

  Examples of materials for extruded profiles are aluminum, aluminum alloys, and those typically suitable for extrusion are 1000-6000-7000 series aluminum alloys.

  An example of a material for the thin layer is a bent aluminum alloy foil with a brazing cladding cladding layer that can be melted at a temperature of 580-600 ° C.

  Examples of the catalyst material are platinum or nickel-based catalysts, or CuZn-based catalysts. These catalysts are typically well suited for applications that reform methanol and other alcohols and hydrocarbons. For example, the catalyst is provided as a cylindrical or spherical pellet having a diameter of 0.5-10 mm and a height of 0.5-10 mm. Alternatively, the pellets have a similar size, but other geometric shapes, such as trapezoids, cubes, hexahedral cross sections, or combinations thereof, with or without hollow portions.

  For the above reasons, using extrusion in the manufacture of such reformers compared to traditional milling or molding of fuel cell reformers with serpentine channels reduces production speed and cost, In addition, many advantages are implied from the viewpoint of ease of size adjustment.

  The present invention will be described in more detail with reference to the drawings.

FIG. 1 shows an example of a fuel cell system. FIG. 2 shows an example of a compact reformer with a serpentine channel. FIG. 3 shows an extrusion reformer with a thin layer brazed. FIG. 4 shows different profiles for the brazed lamina.

  FIG. 1 discloses a fuel cell system 1. The fuel cell system 1 includes a fuel cell stack 2. A liquid fuel, for example, a mixture of methanol and water, is supplied from the fuel supply tank 3 to the fuel cell stack 2. Within the liquid conduit 4, the liquid fuel is guided into the evaporator 5. Within the evaporator 5, the temperature of the liquid fuel is raised until the fuel evaporates. The steam is supplied into the reformer 6 through the steam inlet 23. The reformer catalytically converts the steam to syngas, for example by using a catalyst 7 optionally containing copper. Syngas is mainly composed of hydrogen, carbon dioxide, low water mist and carbon monoxide. The syngas is supplied to the anode side of the proton electrolyte membrane of the fuel cell stack 2 through the syngas outlet 24 and the conduit 8 outside the reformer 6, while oxygen derived from air is typically supplied. The gas is supplied from the gas part 10 to the cathode side of the proton electrolyte membrane.

  In order to reach a temperature suitable for the conversion process in the reformer 6, for example about 280 ° C., it is advantageous to employ a burner 11 which typically uses the anode waste gas 12 for combustion. For example, the exhaust gas 13 of the burner 11 has a temperature of 350 to 400 ° C., and is typically reformed by guiding the exhaust gas 13 along the outer wall of the reformer 6 inside the casing 32 as illustrated. Used to heat vessel 6 wall. The gas 13 is also advantageously used to heat the evaporator 5.

  Optionally, when evaporating in the evaporator 5, the coolant 14 having a high temperature of 120 to 200 ° C., for example, 170 ° C. is transferred from the outlet portion of the fuel cell stack 2 to the evaporator 5, and from the coolant to the liquid fuel. Guided to transfer heat to evaporate.

  As an example, the following parameters are applied. For an HTPEM stack delivering 5 kW, a typical dimension is 0.5 m × 0.25 m × 0.15 m. For example, the weight of the fuel cell stack including the burner, the evaporator, and the reformer is about 20 kg, and the weight of the entire fuel cell system including the electronic device, the coolant pump, the first heat exchanger, and the valve is 40 to 45 kg. It is an order.

  FIG. 2 is a cross-sectional view showing a possible reformer 6 with a serpentine channel 15. The serpentine channel 15 is provided by two comb-like sets 16 of guide walls 17. The guide walls 17 extend from facing walls 18 and 19 facing each other and are offset from each other by half of a comb-period 20. The length 21 of the guide wall 17 is greater than half the distance 22 between the opposing walls 18, 19, thereby preventing straight movement of the steam and forcing the steam along the serpentine channel 15. move. For example, the length 21 of the guide wall is 60% to 90% of the distance 22 between the opposing walls 18 and 19.

  The reformer 6 includes an inlet 23 for fuel vapor at one end of the serpentine channel 15 and an outlet 24 for syngas at the opposite end of the serpentine channel 15. Inside the reformer 6, along with the meandering flow path 15, the reformer catalyst material 25 is provided as pellets as shown in the figure, for example. The pellets 25 are shown only at one corner of the reformer 6, but in reality are distributed throughout the serpentine channel 15 and along the serpentine channel 15.

  As another embodiment, the serpentine channel 15 may be larger in that the cross section of the serpentine channel 15 increases toward the syngas outlet 24. In this way, the steam and the generated syngas can be gradually expanded during the conversion. In this case, the comb period 20 is not constant, and increases along the distance from the steam inlet 23 to the syngas outlet 24.

  The reformer 6 of FIG. 2 is provided as a box-shaped extruded profile 31. However, a reformer can also be formed by assembling two extruded profiles 31a, 31b. The two extruded profiles have an assembly contact area along the location of the profile 31 as indicated by the break line 34.

  FIG. 3 is a three-dimensional view showing the structure of the extrusion reformer 6, similar to the reformer of FIG. The metal profile 31 of the reformer 6 includes two comb sets of guide walls 17 that are offset by half a fixed period, the length of the guide walls being approximately 75 of the distance between the opposing walls. %. The reformer 6 includes a steam inlet 23 at one end and a corresponding syngas outlet at the opposite end that is not visible in the image. The end 26 of the reformer 6 when viewed from a direction perpendicular to the serpentine channel 15 is shown open, but is usually closed with a wall element. The four corners 27 include a stabilizing quadrant 28. These quadrants 28 join each of the two wall sections that meet at one of the four corners.

  As can be seen from the normal direction to the meandering flow path 15, the reformer 6 is a rectangle, which has two opposing long sides from which the comb-like assembly of the guide walls 17 extends, It has short sides provided with a steam inlet 23 and a syngas outlet, respectively. A thin metal layer 29 is provided on the long side, and the thin metal layer is typically brazed to the long side of the extruded portion of the reformer 6. These thin layers 29 ensure proper heat transfer from the exhaust gas 13 of the burner 11. The exhaust gas 13 is guided along the thin layer 29 and heats the thin layer 29. The thin layer 29 then conducts heat to the extruded portion of the reformer 6. Heat is then conducted through the walls to provide heat on the reformer inner walls 18,19.

  In manufacturing, the deformed material is extruded in a direction parallel to the guide wall 17. Useful materials include aluminum and aluminum containing alloys. When extruded, the deformed material is cut in a direction perpendicular to the extrusion direction 30. Before starting the reformer 6, the open end 26 is covered with a wall element. Each end of the serpentine channel 15 is provided with an opening 23 for the steam inlet and a further opening for the syngas outlet. A thin metal layer 29 on one side, or two sides, or more than two sides, to increase the surface area that can receive heat from the hot air 13 guided along the outside of the reformer 6 cover. For example, as shown in FIG. 3, the two largest sides are covered with a thin layer 29. The thin layer 29 extends parallel to the serpentine flow path 15. The serpentine channel 15 is perpendicular to the extrusion direction 30 and perpendicular to the guide wall 17. As can be seen in FIG. 3, a funnel-shaped guide 31 is provided at the end of the thin layer 29 to collect the exhaust gas before it is released.

  The reformer 6 is pushed out in a direction perpendicular to the serpentine flow path 15, and steam and syngas flow across the reformer 6 along the serpentine flow path 15. Or it can be easily cut into an accurate width with respect to the width of the plurality of fuel cell stacks 2. As shown in FIG. 3, the reformer 6 provides syngas to the three fuel cell stacks 2 and has a width corresponding to the entire width of the three fuel cell stacks. The open side 26 remaining after cutting the extruded profile is covered by a wall element (not shown) when preparing the reformer 6 for use.

  As shown in FIG. 4, the thin layer 29 can be formed into various forms, such as a plain, perforated, serrated, or herringbone type thin layer. The illustrations are not exhaustive of possible shapes. Although the illustrated lamina is folded into a corrugation shape with a square cross-sectional profile, a triangular or quasi-sinusoidal cross-sectional profile is also possible.

  In one embodiment shown in FIG. 5, the guide wall 17 includes a stem 32 and vanes 33 extending laterally from the stem 32. The vanes 34 may have shapes other than those shown and other angles with respect to the stem 32. Alternatively, the stem 33 is curved and not straight as shown in FIG.

  The present invention relates to a method for manufacturing a reformer in a fuel cell system.

  When using a liquid fuel for a power generation fuel cell, hydrogen for the fuel cell is produced by converting the liquid fuel into a synthesis gas, also called a syngas containing a large amount of gaseous hydrogen. An example of a liquid fuel is a mixture of methanol and water, but other liquid fuels, particularly other alcohols including ethanol, can also be used. For conversion, a syngas for the fuel cell is provided by evaporating liquid fuel in the evaporator and catalytic conversion in the reformer. In order to reach the required conversion temperature of 250-300 ° C., the reformer must be heated, for example by exhaust gas from a burner. The temperature of the burner gas is typically 350-400 ° C.

  A general example of a reformer is disclosed in Patent Document of England (see, for example, Patent Document 1). For proper heat transfer between the hot exhaust gas and the reformer, the reformer is inserted into a rolled corrugated metal or extruded metal radiator core and brazed to it. This approach is similar to the heat exchanger field. In this field, the general teaching is to conduct heat transfer from the media flowing along the fins by extruding the tubes and brazing the thin fins to the outer wall of the tubes. Inside such an extrusion tube, the liquid flows in the same direction as the extrusion direction. This is in accordance with traditional ideas in the technical field of heat exchangers. From the general art of heat exchangers it is known to use a cladding or powder spray on an extruded aluminum core. In the case of an example disclosed in another patent document (see, for example, Patent Document 2), spray application of powder brazing agent is used to braze the corrugated fins onto the extruded aluminum core of the heat exchanger. Another patent document discloses that the corrugated fin is clad before brazing (see, for example, Patent Document 3).

In addition, the cylinder body of the extrusion reformer module disclosed in another patent document has a plurality of channels along the flow direction, which reflects the traditional idea of extrusion ( For example, see Patent Document 4.) A flow parallel to the extrusion direction is disclosed in a fluid processing apparatus disclosed in Caze et al. (See, for example, Patent Document 5). A small integrated heat exchanger having a flow in an opposing direction is disclosed in a certain non-patent document (for example, see Non-patent document 1). The heat exchanger is also disclosed in another non-patent document (for example, see Non-patent document 2).

  While extrusion is a commonly used method for conduits where the fluid flow is along a direction having a constant cross section, extrusion has a more complex structure where the flow is not along a direction having a constant cross section. It is clearly not an advantageous method to use for the reformer.

  High temperature proton exchange membrane fuel cells, also called high temperature proton electrolyte membrane (HTPEM) fuel cells, are advantageous in that they can withstand relatively high CO concentrations and thus do not require a PrOX reactor between the reformer and the fuel cell stack. is there. For this reason, a simple, lightweight and inexpensive reformer can be used. Such a reformer minimizes the overall size and weight of the system, for example in line with the objective of providing a compact fuel cell system for the automotive industry. However, to be efficient while being small in size, the reformer requires a sufficiently long reaction path. This reaction path is typically significantly longer than the outer dimensions of the small reformer. To combine the low weight, small dimensions, and long reaction path, the reaction path is potentially formed as a serpentine path so that the reactants follow a zigzag curve through the reformer. Must.

Such a meandering flow path is also known from a microreactor as disclosed in a certain patent document (for example, see Patent Document 6 ). In this case, the manufacturing method is disclosed as milling or molding. Typically, milling is performed to a predetermined depth of the solid block, the base remains as a solid plate, and the structure extends from the base. Milling or molding is a common method proposed for serpentine structures in fuel cell technology. An example is the manufacture of a solid bipolar plate with serpentine channels as disclosed in another patent document (see, for example, patent document 7 ). Another example of milling or molding is disclosed in another patent document (for example, see Patent Document 8). In still another patent document, the flow path is serpentine and is parallel to the longitudinal direction of the extended protrusions extending from the two plates arranged opposite to each other. Casting and forging for the production of a vessel has been disclosed (for example, see Patent Document 9). In this document, extrusion is mentioned as an alternative, but is not described or exemplified.

  From these disclosures in various technical fields, extrusion is a commonly used method useful for manufacturing tubes with invariant profiles along the tube axis, in the same direction as the extrusion direction. A method in which a fluid flow flows along a direction having an invariant cross-section, whereas milling is due to a more complex profile where the flow does not follow the extrusion direction, for example along a serpentine channel. It seems to be a typical method.

  Milling is versatile and easy to adjust for complex profiles. However, milling has the disadvantage of being relatively slow and thus not optimal for mass production. Milling also implies that a large amount of material waste is generated. This is because the material removed by milling from a block, such as an aluminum block, is not useful and must be discarded. Molding is more suitable for mass production, but not for a closed structure that surrounds the volume. For these reasons, molding imposes restrictions on the manufacturing method and requires additional assembly steps. Molding also requires different molds for different sizes, which increases manufacturing costs.

  Accordingly, it is desirable to find another method of manufacturing a fuel cell reformer with a complex shape, particularly a serpentine channel.

U.S. Pat. No. 7,976,787 European Patent No. 595601 EP 417894 specification China Utility Model No. 202517022 Specification US Patent Application Publication No. 2010/143215 US Pat. No. 8,574,500 International Publication No. 2009/010067 US Patent Application Publication No. 2007/068076 US Patent Application Publication No. 2006/0141295

“High-temperature fuel cell system” on pages 282 to 294 of “Journal of Power Sources” No. 183 (2008), written by Huisheng Zhang, Lijin Wang, Shilie Weng, Ming Su et al. Article titled "Performance research on the compact heat exchange reformer used for high temperature fuel cell systems" At the COOML meeting in Stuttgart in 2011 by SAS SYNGAS P. Gateau, SIMTAC Patrick Namy and COMSOL France Nicolas Huc, “Honeycomb heat exchanger and fin heat Conference paper entitled `` Comparison between honeycomb and fin heat exchangers ''

  Accordingly, it is an object of the present invention to provide an improvement in technology. In particular, it is an object to provide an improved method of manufacturing a fuel reformer in a fuel cell system, especially because of the complex shape deviating from a straight tube. One significant form for a reformer is a serpentine flow path through the reformer, with the goal of finding an improved manufacturing method. This object is solved by the following manufacturing method of the fuel cell system.

  During manufacture, the metal profile is cut perpendicular to the profile to provide the metal profile by extrusion and to provide a reformer housing. The catalyst is provided inside the reformer and the volume is closed by covering the cut end with a wall element. An evaporator is connected to one end, and a fuel cell is connected to the opposite end. In preparation for heating the reformer with hot gas, a thin heat conducting layer is optionally provided on the outer surface.

  In more detail, the following advantageous forms are provided. The extruded profile includes two extruded opposing walls facing each other with a predetermined distance between the walls and a predetermined volume between the walls. This volume is ultimately used for the conversion of steam to syngas. Each of the two walls is an integral group of extruded spaced apart guide walls extending from each of the two walls toward the opposite wall by a distance greater than half the distance between the walls. Including. For example, the length of the guide wall is 60% to 90% of the distance between the opposing walls. The guide wall forms a comb-like structure on each of the two walls. The two comb structures face each other and are offset from each other in the lateral direction so as to mesh with each other and form a serpentine channel in a direction perpendicular to the extrusion direction. Thus, the gas cannot travel along a straight line across the volume in a direction perpendicular to the extrusion direction, but must follow a meandering elongated path.

  For example, a profile provides a box with a square cross-sectional profile by extruding two opposing walls as a box profile joined by additional walls, typically two additional walls facing each other. Alternatively, the profile is provided as two extruded halves of the box profile. These halves are extruded and then assembled into box profiles. For example, each half includes only one of two opposing walls and one group of mutually spaced guide walls extending from one of the walls, and the assembly is on opposite sides. A guide wall is provided to form a serpentine flow path.

  For example, when the guide walls are provided at equal intervals in a certain period and are offset asymmetrically in the direction perpendicular to the extrusion direction by a quarter period in the half profile, The two halves can be provided by extruding a single profile and then cutting the profile into two equal length sections. During assembly, one section is provided in the extrusion direction and the other half is rotated 180 degrees around the extrusion direction and 180 degrees around a line perpendicular to the extrusion direction. Due to the offset of a quarter period, the guide walls mesh with each other with half the period between the meshing guide walls extending opposite to each other.

  An example of a useful material is aluminum or an aluminum alloy, such as a wrought alloy. The thermal conductivity is relatively high because it conducts heat from outside the profile into the volume inside the reformer. This is because this volume will be used for the catalytic conversion of fuel vapor to syngas, which typically requires temperatures above about 250 ° C. For example, to withstand burner gases at temperatures above 300 degrees, the alloy is advantageously a 5000 series aluminum alloy containing aluminum and magnesium, or a 6000 series aluminum alloy containing aluminum, magnesium and silicon. .

  A steam inlet and a syngas outlet are provided in the profile at opposite ends of the serpentine steam channel to allow the steam to flow into the volume and the syngas to flow out of the volume. For example, holes are formed in the metal profile and conduits are attached to these holes. The conduit is later used to fluidly connect the liquid fuel evaporator to the vapor inlet and the fuel cell to the syngas outlet.

  Depending on the desired width of the reformer, the profile is cut perpendicular to the extrusion direction and also perpendicular to the serpentine channel. Extrusion allows a single extrusion profile to provide portions for multiple reformer housings. Each of these parts is cut from the extruded profile at a length suitable for the purpose. For example, one cut piece of profile is short and can be used for a reformer connected to a single fuel cell stack, and another cut piece is long and syngas is applied to multiple fuel cell stacks. It can be used for the reformer provided.

  Thus, it can be seen that extrusion not only simplifies the production of the reformer, but is also flexible in terms of size adjustment. In the case of molding, such flexibility is not given. This is because each size change requires a different molding type. The work associated with small and large reformers is not much different when using extrusion. This is also in stark contrast to the case where milling is used in manufacturing. Although milling is generally versatile, the larger the reformer, the more time it takes to perform the milling process, and the milling that is performed to a very deep depth is mechanical in terms of accuracy and stability. It is difficult to. For these reasons, milling is not suitable for large reformers, in addition to the disadvantage that a large amount of milling material is discarded. Overall, extrusion to produce a reformer is advantageous in several aspects.

  A catalyst material, such as catalyst pellets, is inserted into the volume. The volume is then closed by a wall element that provides a closed reformer housing for catalytic conversion of fuel vapor to syngas in the volume inside the housing.

  In operation, a suitable temperature for the catalytic conversion process inside the housing, typically 250-300 degrees when the fuel is a mixture of methanol and water, and higher alcohol or diesel is used as the fuel In some cases, the reformer housing is heated to provide a higher temperature.

  Although electrical heating is possible to regulate the temperature in the reformer, a useful way to provide this necessary heat is to direct hot gas along the outside of the metal profile, The metal introduces heat into the reformer volume. A thin layer of parallel metal is brazed to the outside of the housing for efficient heat transfer from the hot gas. For example, to provide such a thin layer, a thin sheet material is folded into a corrugated structure and brazed on its surface before brazing to the outside of the reformer housing. Optionally, the thin layer is provided on at least two sides of the profile, for example on opposite sides. In order to obtain a high heat transfer effect, it is advantageous if one or more of the largest sides of the profile are covered with a thin layer. For example, if the reformer volume has a rectangular cross section with two long sides and two short sides, the thin layer is provided on the long side.

  In order to guide the hot gas along the lamina, the reformer housing is surrounded by a casing. The casing has a burner gas inlet at one end of the parallel metal lamina and a burner gas outlet at the opposite end so that the gas is guided along the lamina surface. The burner gas inlet is then fluidly connected to the burner.

  As long as the profiled material is extruded, as long as the profiled profile has an invariable cross section along the extrusion direction of the profiled material, the wall can be easily made with various cross-sectional shapes, including straight or bent shapes, for example wave shapes Can be formed. The shape of the guide wall affects the flow rates of the steam and syngas that pass through the serpentine channel perpendicular to the extrusion direction. In addition, the guide wall optionally comprises vanes to create turbulence and mixing and to guide the gas toward the center of the serpentine channel for optimization of the catalytic conversion process. For example, in cross-section, the guide wall includes a straight or curved stem that extends from one of the two opposing walls to the other. The stem then includes vanes extending from the stem, eg, vanes extending laterally from the stem, to provide obstructions and corresponding turbulence along the serpentine steam flow path. When the stem is provided with a plurality of blades, the shape of the fish bone is one option when viewed in cross section.

  Examples of materials for extruded profiles are aluminum, aluminum alloys, and those typically suitable for extrusion are 1000-6000-7000 series aluminum alloys.

  An example of a material for the thin layer is a bent aluminum alloy foil with a brazing cladding cladding layer that can be melted at a temperature of 580-600 ° C.

  Examples of the catalyst material are platinum or nickel-based catalysts, or CuZn-based catalysts. These catalysts are typically well suited for applications that reform methanol and other alcohols and hydrocarbons. For example, the catalyst is provided as a cylindrical or spherical pellet having a diameter of 0.5-10 mm and a height of 0.5-10 mm. Alternatively, the pellets have a similar size, but other geometric shapes, such as trapezoids, cubes, hexahedral cross sections, or combinations thereof, with or without hollow portions.

  For the above reasons, using extrusion in the manufacture of such reformers compared to traditional milling or molding of fuel cell reformers with serpentine channels reduces production speed and cost, In addition, many advantages are implied from the viewpoint of ease of size adjustment.

  The present invention will be described in more detail with reference to the drawings.

FIG. 1 shows an example of a fuel cell system. FIG. 2 shows an example of a compact reformer with a serpentine channel. FIG. 3 shows an extrusion reformer with a thin layer brazed. FIG. 4 shows different profiles for the brazed lamina.

  FIG. 1 discloses a fuel cell system 1. The fuel cell system 1 includes a fuel cell stack 2. A liquid fuel, for example, a mixture of methanol and water, is supplied from the fuel supply tank 3 to the fuel cell stack 2. Within the liquid conduit 4, the liquid fuel is guided into the evaporator 5. Within the evaporator 5, the temperature of the liquid fuel is raised until the fuel evaporates. The steam is supplied into the reformer 6 through the steam inlet 23. The reformer catalytically converts the steam to syngas, for example by using a catalyst 7 optionally containing copper. Syngas is mainly composed of hydrogen, carbon dioxide, low water mist and carbon monoxide. The syngas is supplied to the anode side of the proton electrolyte membrane of the fuel cell stack 2 through the syngas outlet 24 and the conduit 8 outside the reformer 6, while oxygen derived from air is typically supplied. The gas is supplied from the gas part 10 to the cathode side of the proton electrolyte membrane.

  In order to reach a temperature suitable for the conversion process in the reformer 6, for example about 280 ° C., it is advantageous to employ a burner 11 which typically uses the anode waste gas 12 for combustion. For example, the exhaust gas 13 of the burner 11 has a temperature of 350 to 400 ° C., and is typically reformed by guiding the exhaust gas 13 along the outer wall of the reformer 6 inside the casing 32 as illustrated. Used to heat vessel 6 wall. The gas 13 is also advantageously used to heat the evaporator 5.

  Optionally, when evaporating in the evaporator 5, the coolant 14 having a high temperature of 120 to 200 ° C., for example, 170 ° C. is transferred from the outlet portion of the fuel cell stack 2 to the evaporator 5, and from the coolant to the liquid fuel. Guided to transfer heat to evaporate.

  As an example, the following parameters are applied. For an HTPEM stack delivering 5 kW, a typical dimension is 0.5 m × 0.25 m × 0.15 m. For example, the weight of the fuel cell stack including the burner, the evaporator, and the reformer is about 20 kg, and the weight of the entire fuel cell system including the electronic device, the coolant pump, the first heat exchanger, and the valve is 40 to 45 kg. It is an order.

  FIG. 2 is a cross-sectional view showing a possible reformer 6 with a serpentine channel 15. The serpentine channel 15 is provided by two comb-like sets 16 of guide walls 17. The guide walls 17 extend from facing walls 18 and 19 facing each other and are offset from each other by half of a comb-period 20. The length 21 of the guide wall 17 is greater than half the distance 22 between the opposing walls 18, 19, thereby preventing straight movement of the steam and forcing the steam along the serpentine channel 15. move. For example, the length 21 of the guide wall is 60% to 90% of the distance 22 between the opposing walls 18 and 19.

  The reformer 6 includes an inlet 23 for fuel vapor at one end of the serpentine channel 15 and an outlet 24 for syngas at the opposite end of the serpentine channel 15. Inside the reformer 6, along with the meandering flow path 15, the reformer catalyst material 25 is provided as pellets as shown in the figure, for example. The pellets 25 are shown only at one corner of the reformer 6, but in reality are distributed throughout the serpentine channel 15 and along the serpentine channel 15.

  As another embodiment, the serpentine channel 15 may be larger in that the cross section of the serpentine channel 15 increases toward the syngas outlet 24. In this way, the steam and the generated syngas can be gradually expanded during the conversion. In this case, the comb period 20 is not constant, and increases along the distance from the steam inlet 23 to the syngas outlet 24.

  The reformer 6 of FIG. 2 is provided as a box-shaped extruded profile 31. However, a reformer can also be formed by assembling two extruded profiles 31a, 31b. The two extruded profiles have an assembly contact area along the location of the profile 31 as indicated by the break line 34.

  FIG. 3 is a three-dimensional view showing the structure of the extrusion reformer 6, similar to the reformer of FIG. The metal profile 31 of the reformer 6 includes two comb sets of guide walls 17 that are offset by half a fixed period, the length of the guide walls being approximately 75 of the distance between the opposing walls. %. The reformer 6 includes a steam inlet 23 at one end and a corresponding syngas outlet at the opposite end that is not visible in the image. The end 26 of the reformer 6 when viewed from a direction perpendicular to the serpentine channel 15 is shown open, but is usually closed with a wall element. The four corners 27 include a stabilizing quadrant 28. These quadrants 28 join each of the two wall sections that meet at one of the four corners.

  As can be seen from the normal direction to the meandering flow path 15, the reformer 6 is a rectangle, which has two opposing long sides from which the comb-like assembly of the guide walls 17 extends, It has short sides provided with a steam inlet 23 and a syngas outlet, respectively. A thin metal layer 29 is provided on the long side, and the thin metal layer is typically brazed to the long side of the extruded portion of the reformer 6. These thin layers 29 ensure proper heat transfer from the exhaust gas 13 of the burner 11. The exhaust gas 13 is guided along the thin layer 29 and heats the thin layer 29. The thin layer 29 then conducts heat to the extruded portion of the reformer 6. Heat is then conducted through the walls to provide heat on the reformer inner walls 18,19.

  In manufacturing, the deformed material is extruded in a direction parallel to the guide wall 17. Useful materials include aluminum and aluminum containing alloys. When extruded, the deformed material is cut in a direction perpendicular to the extrusion direction 30. Before starting the reformer 6, the open end 26 is covered with a wall element. Each end of the serpentine channel 15 is provided with an opening 23 for the steam inlet and a further opening for the syngas outlet. A thin metal layer 29 on one side, or two sides, or more than two sides, to increase the surface area that can receive heat from the hot air 13 guided along the outside of the reformer 6 cover. For example, as shown in FIG. 3, the two largest sides are covered with a thin layer 29. The thin layer 29 extends parallel to the serpentine flow path 15. The serpentine channel 15 is perpendicular to the extrusion direction 30 and perpendicular to the guide wall 17. As can be seen in FIG. 3, a funnel-shaped guide 31 is provided at the end of the thin layer 29 to collect the exhaust gas before it is released.

  The reformer 6 is pushed out in a direction perpendicular to the serpentine flow path 15, and steam and syngas flow across the reformer 6 along the serpentine flow path 15. Or it can be easily cut into an accurate width with respect to the width of the plurality of fuel cell stacks 2. As shown in FIG. 3, the reformer 6 provides syngas to the three fuel cell stacks 2 and has a width corresponding to the entire width of the three fuel cell stacks. The open side 26 remaining after cutting the extruded profile is covered by a wall element (not shown) when preparing the reformer 6 for use.

  As shown in FIG. 4, the thin layer 29 can be formed into various forms, such as a plain, perforated, serrated, or herringbone type thin layer. The illustrations are not exhaustive of possible shapes. Although the illustrated lamina is folded into a corrugation shape with a square cross-sectional profile, a triangular or quasi-sinusoidal cross-sectional profile is also possible.

  In one embodiment shown in FIG. 5, the guide wall 17 includes a stem 32 and vanes 33 extending laterally from the stem 32. The vanes 34 may have shapes other than those shown and other angles with respect to the stem 32. Alternatively, the stem 33 is curved and not straight as shown in FIG.

Claims (8)

In the manufacturing method of the fuel cell system (1),
The manufacturing method is
Providing a metal profile (31) by extrusion, wherein the extruded profile (31) is extruded into two opposing walls (18, 19) and the two opposing walls (18 , 19) with a predetermined distance (22) and a predetermined volume between the two opposing walls, each of the two opposing walls (18, 19) being A plurality of extruded, spaced-apart, plurality extending from each of the two opposing walls (18, 19) by a distance (21) longer than half of the distance (22) between the walls (18, 19). A group of guide walls (17) is integrally included, and the guide wall (17) forms a comb-like structure on each of the two opposing walls (18, 19). Are facing each other, meshing with each other and Serial serpentine vapor flow path in a direction perpendicular to the extrusion direction (30) (15) so as to form a are offset laterally, the steps,
Providing a steam inlet (23) and a syngas outlet (24) in the profile (31) at opposite ends of the serpentine steam channel (15),
The manufacturing method further comprises:
For cutting the profile (31) in a direction perpendicular to the extrusion direction (30), inserting a catalyst material (25) into the volume, and catalytic conversion of fuel vapor into syngas in the volume Closing the volume with a wall element to provide a closed reformer (6) housing; and
Brazing a thin parallel metal layer (29) to the outside of the housing to conduct heat from the parallel metal thin layer (29) to the metal profile (31) and into the volume;
The housing and the thin parallel metal layer (29) are surrounded by a casing (32), the casing (32) having a burner gas inlet at one end of the thin parallel metal layer (29) and the opposite end. Having a burner gas outlet in the part, and
Connecting a liquid fuel evaporator (5) to the vapor inlet (23), connecting a fuel cell to the syngas outlet (24), and connecting a burner (11) to the burner gas inlet. Manufacturing method of fuel cell system (1).   The method according to claim 1, wherein the length (21) of the guide wall (27) is between 60% and 90% of the distance (22) between the two opposing walls (18, 19).   The guide wall (17) includes a stem (33) extending from the two opposing walls (18, 19) when viewed in a cross-sectional view, the stem obstructing along the serpentine steam channel (15) 3. A method according to claim 1 or 2, comprising a plurality of vanes (34) extending from said stem (33) to provide an object and corresponding turbulence.   4. The method according to claim 3, wherein the guide wall (17) is extruded as a fish bone shape when viewed in cross-section.   5. The method according to claim 1, wherein the profile (31) is extruded as a box profile with the two opposing walls (18, 19) joined by a further wall. 6. .   Said profile (31) is provided as two extruded halves (31a, 31b) of the box profile (31), each half (31a, 31b) being said two opposing walls (18 , 19) and a group of extruded guide walls (17) spaced apart from each other, the method comprising said two halves (31a, 31b) 5. The method according to any one of claims 1 to 4, wherein the box profile (31) is assembled by assembling after extrusion.   The catalyst material (25) is provided as catalyst pellets, and the method comprises filling the volume between the guide walls (17) with the catalyst pellets, wherein the catalyst pellet size is 0.5 to The method according to claim 1, which is 11 mm.   A fuel cell system (1) manufactured by the method according to any one of claims 1-7.