Abstract:
Apparatus and methods for the production of hydrogen using a reformer including a housing, a first plate having a first plurality of fin structures and a second plate having a second plurality of fin structures assembled such that the first plurality of fin structures is interleaved with the second plurality of fin structures. At least one inlet port is formed in at least one of the first plate and the second plate, and at least one outlet port formed in at least one of the first plate and the second plate. The fin structures may be coated with a catalytic material to enhance or stimulate reactions taking place within the apparatus. A heat exchange device may also be integrated into one or both plates of the reformer.

Description:
TECHNOLOGICAL FIELD 
       [0001]    The present invention relates generally to the production of hydrogen and, more specifically, to the production of hydrogen through the use of hydrocarbon auto-thermal reformers which may include an integral heat exchanger and systems incorporating such reformers. 
       BACKGROUND 
       [0002]    Fuel cells are widely recognized as being promising alternative energy devices. Generally, fuel cells generate clean electric power quietly without directly combusting fuels. Fuel cells operate by converting chemical energy (such as from O 2  and H 2 ) into electricity in a relatively efficient manner. For example, proton exchange membrane (PEM) fuel cells are considered to be approximately 40% efficient, phosphoric acid fuel cells (PAFC) are considered to be approximately 45% efficient and molten carbonate fuel cells (MCFC) and solid oxide fuel cells (SOFC) are considered to be between approximately 40% to 80% efficient depending on their specific configurations. The greater the efficiency of a fuel cell, the greater conservation of energy, as well as the lower the emissions of CO 2 . 
         [0003]    Considerable efforts have been expended to develop and manufacture fuel cells as alternative power sources for a variety of products. For example, fuel cells have been developed for use in automotive applications. Additionally, efforts have been made to develop fuel cells to replace batteries for a variety of electronic devices, including cell phones and laptop computers. 
         [0004]    Many fuel cells, such as PEM fuel cells, operate using a process that requires hydrogen. Hydrogen may be produced in a variety of ways including, for example, electrolysis, high temperature electrolysis, thermochemical, or through reforming processes. Considerable efforts have been made to improve the production of hydrogen. In many cases, it becomes desirable to produce hydrogen on site or “on-demand” rather than having to require bulk storage of hydrogen. 
         [0005]    Reforming is a process used to produce hydrogen gas from hydrocarbons using an appropriate catalyst. For example, one type of reforming is known as steam-methane reforming (SMR). In the SMR process, methane reacts with steam on a nickel catalyst to produce hydrogen and carbon monoxide (also know as synthesis gas or “syngas”) according to the following chemical equation: 
         [0000]      CH 4 +H 2 O→CO+3H 2  
 
         [0006]    The SMR process is conventionally carried out at temperatures of approximately 850° C. and at pressure levels of approximately 1 to 2 megaPascals (MPa). The SMR process is endothermic and conventionally uses an external source of hot gas to heat tubes in which the catalytic reaction takes place. 
         [0007]    Another reforming process is known as auto-thermal reforming (ATR). In one form, the ATR process uses oxygen and carbon dioxide in a reaction with methane to form hydrogen and carbon monoxide according to the following chemical equation: 
         [0000]      2CH 4 +O 2 +CO 2 →3H 2 +3CO+H 2 O+Heat
 
         [0008]    In another form, the ATR process uses oxygen and steam in a reaction with methane according to the following chemical equation: 
         [0000]      2CH 4 +O 2 +H 2 O→5H 2 →3CO+2CO
 
         [0009]    Yet another reforming process is known as partial oxidation which produces syngas according to the following chemical reaction: 
         [0000]      CH 4 +H 2 O→2H 2 +CO
 
         [0010]    It is desirable within the industry to continually improve hydrogen production processes including the various reforming processes. It is also desirable within the industry to improve the apparatuses, systems and methods associated with the production of hydrogen such as may be used with fuel cells and other devices. 
       BRIEF SUMMARY 
       [0011]    Embodiments described herein include apparatuses for producing hydrogen, reformers, reformer systems and related methods. For example, in accordance with one embodiment described herein, an apparatus for producing hydrogen comprises a first plate having a first plurality of fin structures and a second plate having a second plurality of fin structures. The first plate and the second plate are assembled such that the plurality of fin structures on the first plate is interleaved with the plurality of fin structures on the second plate. At least one inlet port is formed in at least one of the first plate and the second plate, and at least one outlet port formed in at least one of the first plate and the second plate. 
         [0012]    In certain embodiments described herein, the apparatus may further include an integrated heat exchange device associated with either the first plate, or the second plate, or both the first plate and the second plate. Additionally, the second plate may include a third plurality of fin structures. The apparatus may include a third plate having a further plurality of fin structures on one side thereof or both sides thereof. The third plate and the second plate may be assembled such that the third plurality of fin structures and the fourth plurality of fin structures are interleaved with one another. The first plate, the second plate, and the third plate may be assembled such that the first plurality of fin structures of the first plate are interleaved with the third plurality of fin structures of the third plate and the second plurality of fin structures of the second plate are interleaved with the fourth plurality of fin structures of the third plate. One or more fin structures of the first plate, the second plate, and the third plate may be configured to include a flow path through at least a portion thereof. Another flow path may be configured between adjacent fin structures. Additionally, the fin structures may be coated with a catalytic material to enhance or stimulate a desired reaction taking place within the apparatus. 
         [0013]    In accordance with another embodiment described herein, a method of forming a reformer apparatus is described. The method includes providing a first plate having a first plurality of fin structures and providing a second plate having a second plurality of fin structures. The first plate and the second plate are assembled such that the first plurality of fin structures and the second plurality of fin structures are interleaved with respect to each other. A first flow path is provided through at least a portion of at least one fin structure of the first and second pluralities. A second flow is provided path between adjacent fin structures of the first and second pluralities of fin structures. A coating of catalytic material may be deposited on the fin structures of the first and second plates, if desired. Adjacent fin structures may be arranged and spaced approximately 0.04 inch apart from one another. A heat exchange device with at least one channel is formed in either the first plate and/or the second plate in one embodiment described herein. In accordance with another embodiment described herein, a system comprises at least one water-gas shift reactor, at least one preferential oxidation reactor, and at least one auto thermal reformer, a first plate having a first plurality of fin structures, and a second plate having a second plurality of fin structures. The first plate and the second plate are assembled such that the first plurality of fin structures is interleaved with the second plurality of fin structures. At least one inlet port is formed in at least one of the first plate and the second plate, and at least one outlet port formed in at least one of the first plate and the second plate. 
         [0014]    In certain embodiments described herein, the apparatus may further include an integrated heat exchange device associated with the first plate, the second plate, or both. Additionally, the second plate may include a third plurality of fin structures and apparatus may include a third plate having a further plurality of fin structures. The third plate and the second plate may be assembled such that the third and fourth pluralities of fin structures are interleaved with one another. 
         [0015]    One or more fin structures may be configured to include a flow path through at least a portion thereof. Another flow path may be configured between adjacent fin structures. Additionally, the fin structures may be coated with a catalytic material to enhance or stimulate a desired reaction taking place within the apparatus. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0016]    The foregoing and other advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: 
           [0017]      FIG. 1A  is a perspective view of a reformer according to an embodiment of the present invention; 
           [0018]      FIG. 1B  is a perspective view of the reformer of  FIG. 1A  with a section cut away to show a partial cross-section of the reformer; 
           [0019]      FIG. 2A  is a perspective view of a first portion of the reformer of  FIG. 1A ; 
           [0020]      FIG. 2B  is a perspective view of a second portion of the reformer of  FIG. 1A ; 
           [0021]      FIG. 3  is an enlarged view of a cross-sectioned region of a reformer; 
           [0022]      FIG. 4  is a cross-sectional view of a portion of the reformer shown in  FIG. 1A  including showing various inlet ports according to an embodiment of the present invention; 
           [0023]      FIG. 5A  is a perspective view of a fin of a reformer; 
           [0024]      FIG. 5B  is a partial cross-sectional view of the fin shown in  FIG. 5A ; 
           [0025]      FIG. 6  is a perspective view of a system incorporating a reformer in accordance with an embodiment of the present invention; and 
           [0026]      FIG. 7  is a schematic of the system shown in  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Referring to  FIGS. 1A and 1B , an auto thermal reformer  100  is shown in accordance with an embodiment described herein. The auto thermal reformer  100  includes a first (or top) plate  102 A stacked on, or otherwise coupled with, a second (or bottom) plate  102 B. In one embodiment, a plurality of suitable type fasteners may be used to couple the first plate  102 A to the second plate  102 B, each plate having a well known suitable type seal therewith. When assembled, the plates create a fluid tight chamber therewithin or therebetween. The reformer  100  may be disposed in or mounted to a housing  104  or other type suitable structure depending on the intended environment for the operation of the reformer  100 . In one embodiment, the housing  104  may include an insulating material. For example, in one particular embodiment, the housing  104  may include an alumina silicate material, hydrated calcium carbonate material, magnesium carbonate material, etc. as the insulating material. 
         [0028]    Each plate  102 A and  102 B may include one or more ports  106 A for introducing fluid components into the reformer  100  (or more specifically, into the fluid chamber formed by the plate  102 A assembled to the plate  102 B) and one or more ports  106 B for discharging fluid components from the reformer  100 . One, or both, of the plates  102 A and  102 B may be configured to incorporate or otherwise be coupled with a heat exchanger. For example, a recess  108  may be formed in a plate (e.g., plate  102 A) to complementarily receive one or more heat exchange devices as will be discussed in further detail hereinbelow. 
         [0029]    Referring to  FIG. 1B  in conjunction with  FIGS. 2A and 2B , the plates  102 A and  102 B may include a plurality of fin structures (referred to as fins herein for purposes of convenience and designated as fin structure  110 A for a fin structure associated with the first plate  102 A and fin structure  110 B for a fin structure associated with the second plate  102 B). The fin structure  110 A or fin structure  110 B for a plate  102 A or plate  102 B runs in a generally parallel direction to one another and may run along the length of the plate  102 A and plate  102 B. The plate  102 A and plate  102 B are configured such that their respective fin structure  110 A and fin structure  110 B are interleaved with one another when the plate  102 A and plate  102 B are assembled such as illustrated in  FIG. 1A  and  FIG. 3 . In other words, except for a laterally outermost fin of a fin structure  110 A and fin structure  100 B, the fins of fin structure  110 A of the first plate  102 A are generally disposed between fins of fin structure  110 B of the second plate  102 B. Such a configuration results in an alternating lateral arrangement of a fin of fin structure  110 A from the first plate  102 A and a fin of fin structure  110 B from the second plate  102 B. The fins  110 A and  110 B of the two plates  102 A and  102 B do not laterally touch or engage each other. Thus, a fluid flow path is formed or exists between adjacent fins of fin structure  110 A and fin structure  110 B. Additionally, the fins of fin structure  110 A and fin structure  110 B may be coated with a suitable catalytic material to assist in a desired reaction of products flowing through the reformer  100 . Examples of suitable catalytic materials include platinum, palladium, and alloys thereof. 
         [0030]    As illustrated in  FIG. 3 , and discussed herein, a heat exchanger  112  may be associated with the first plate  102 A (or the second plate  102 B or both plate  102 A and plate  102 B). The heat exchanger  112  may include any suitable material configured to conduct heat away from the plate  102 A and to another device, system or environment. In one embodiment, the heat exchanger  112  may include a fluid flowing through channels  108 ′ of the recess  108  such that the fluid carries the heat away from the plates  102 A and  102 B. In such, the fluid may carry transfer heat to another device, system or environment, or it may utilize the heat (or a portion of the heat) to further an associated process or otherwise preparing a fluid for subsequent process operations. In one instance, heat from the heat exchanger  112  may be utilized to vaporize a hydrocarbon fuel, water and air prior to their entry into the reformer  100 . 
         [0031]    As also shown in  FIG. 3 , one or more plenums  114  may be formed upon assembly of the plate  102 A and the plate  102 B. Such plenums  114  may act as exhaust plenums with product fluid flowing between the fins  110 A and  110 B into such plenums  114  and then out exhaust ports  106 B. The plenums  114  may also be associated with a desulfurization process as the plenums allow for the insertion of a suitable replaceable desulfurization cartridge  114 ′ (a removable and replaceable sulfur filter). 
         [0032]    Referring briefly to  FIG. 4 , a perspective end view of another embodiment of a reformer  200  is shown. The reformer  200  includes a first (top) plate  202 A, a second (bottom) plate  202 B and a third (central) plate  202 C. Each plate  202 A,  202 B and  202 C includes a plurality of fins  210 A,  210 B and  210 C respectively. The first plate  202 A and the second plate  202 B are generally similar to those described hereinabove with respect to  FIGS. 1A ,  1 B,  2 A,  2 B and  3 . The third plate  202 C includes fins  210 C extending from two opposing sides thereof. When assembled, the fins  210 A of the first plate  202 A are interleaved with fins  210 C on one side of the third plate  202 C in a manner such as described herein, while the fins  210 B of the second plate  202 C are interleaved with the fins  210 C of the second side of the third plate  202 C in a manner similar to that which has been described herein. The use of a third plate  202 C such as illustrated in  FIG. 4  provides additional surface area for reactions to take place within the reformer  200 . The additional plates, such as plate  202 C having fins on multiple sides, may be used in any reformer to further example flow capacity thereof. 
         [0033]    Referring now to  FIGS. 5A and 5B , further details are shown of a fin (referred to generally as fin  110  for convenience). The fin  110  includes a plurality of longitudinally extending channels  120  ( FIG. 5B , see also  FIG. 4 ) within the fin  110  that extend from one end of the fin  110  towards the opposing end of the fin  110  for any desired distance. One or more cross channels  122  extend from a surface  110 ′ of the fin  110  intersecting the channels  120 , or of the plate (e.g., plate  102 A or plate  102 B) that includes the fin  110 , with the cross channels  122  intersecting the channels  120  at any desired angle relative to the longitudinally extending channels  120 . The longitudinally extending channels  120  and the cross channels  122  are in fluid communication with one another such that fluid flowing through the longitudinally extending channels  120  and fluid flowing through the cross channels  122  mix with one another and then exit the fin  110  through a plurality of apertures  124  or exit ports. 
         [0034]    For example, in one embodiment, a fuel product may flow through the longitudinally extending channels  120  and intermix with air flowing through the cross channels  122 . The two fluids may react to form a desired product which flows out of the apertures  124  and along the external surfaces of the fins  110  initially in a direction substantially counter or perpendicular to the direction of fluid flow in the longitudinally extending channels  120 . 
         [0035]    A reformer configured according to the example embodiments described herein provides numerous advantages. For example, the components of a reformer as described herein are readily manufactured with each plate being individually constructed and the reformer subsequently assembled from such plates. Additionally, catalyst materials are readily deposited onto the fins of the plates. Not only is such an advantage during initial manufacturing, but also during reconditioning of the reformer wherein new layers of catalytic material may be applied to the fins. The example embodiments also provide the advantage of minimizing thermal mass of the reformer which enables a faster start-up of the reformer during operation. Further, temperature gradients are minimized across the height of the reformer which helps to maintain the integrity of the fins as well as the flow paths therebetween. 
         [0036]    Referring now to  FIGS. 6 and 7 , a system  300  is illustrated which includes an autothermal reformer (ATR)  302 , a water gas shift (WGS) reactor  304 , and a preferential oxidation (PROX) reactor  306 . The ATR  302  may be constructed in a manner such as described herein with respect to the various embodiments of a reformer. A bulkhead  308  (not shown in  FIG. 6 , shown in  FIG. 7 ) is typically positioned between the ATR  302  and the PROX reactor  306  to segregate, or selectively segregate, some or all of the fluid flows that occur in each device. 
         [0037]    In one example, a liquid flow of fuel and water is vaporized and enters the ATR  302  as indicated by flow line  310 . The fuel-water mixture flows through the fins of the ATR, such as through the longitudinally extending channels  120  of the fin  110  ( FIG. 5B ) as is indicated by flow line  312 . Air enters the ATR  302 , as indicated by flow line  314 , and is mixed with the fuel-water mixture to react and form a desired product. For example, a fuel such as JP-8 (a jet fuel standard specified by the United States government in 1990, also know as NATO code F-34, MIL-DTL-83133 and British Defence Standard 91-87), may be mixed with water and vaporized. The reaction product, which may include H 2 , flows between fins (see, e.g., fins  110 A,  110 B and  110 C in  FIG. 4 ) as indicated by flow line  316 . 
         [0038]    The ATR may utilize a catalytic partial oxidation reaction, which is an exothermic reaction, combined with an endothermic catalytic steam reforming reaction to produce an H 2  and CO rich stream. The partial oxidation reaction may include a chemical reaction according to the following equation: 
         [0000]      CH 4 +½O 2 →2H 2 +CO
 
         [0039]    The steam reforming reaction may include a chemical reaction according to the following equation: 
         [0000]      CH 4 +H 2 O→3H 2 +CO
 
         [0040]    The reaction products may then flow through the WGS reactor  304  and be subjected to further processing as indicated by flow line  318 . Cooling air may also flow through the WGS reactor  304  as indicated by flow line  320 . 
         [0041]    Generally, the WGS process may include a water splitting process which may be used to obtain additional H 2 . The WGS  304  reactor may employ a chemical process according to the following equation: 
         [0000]      CO+H 2 O→CO 2 +H 2  
 
         [0042]    The product stream may then enter the PROX reactor  306  for further processing of the product as indicated by flow line  322 . The PROX reactor  306  may use a process to convert CO to CO 2  and to produce additional H 2 . Cooling air may also flow through the PROX reactor as indicated by flow line  324 . H 2  product then exits the PROX reactor  306  as indicated by flow line  326 . 
       Example 
       [0043]    One particular example of an auto thermal reformer (ATR) is now set forth with general reference to drawing figures. The ATR according to the present example is configured to provide an appropriate volume of H 2  to a 2 kW PEM fuel cell. 
         [0044]    The ATR (e.g., ATR  302 ) is sized to provide 37 standard liters per minute (SLPM) of H 2  for a fuel cell that will have an efficiency of approximately 50%. A fuel of JP-8 with water and air will be used to produce H 2 . A combined flow through of JP-8, air and H 2 O will be 100.15 SLPM. The molar fractions of JP-8, H 2 O and O 2  will be, respectively, 0.013269639, 0.291932059 and 0.694798301. The steam-to-carbon ratio will be 2.0 and the oxygen-to-carbon ration will be 1.0. The Volumetric Hourly Space Velocity will be 30,000 per hour. 
         [0045]    The plates (e.g., plate  102 A and plate  102 B) of the ATR are configured of a ferritic alloy material (e.g., FeCrAl) that will be capable of continual operation at approximately 1400° C. The fins (e.g.,  110 ) of the ATR will exhibit a length of approximately 10 inches, a height of approximately 0.5 inch, and a width of approximately 0.088 inch. A catalytic material comprising platinum, palladium, and alloys thereof may be deposited on the fins of the ATR at a thickness of approximately 0.006 inch. The flow path width (i.e., the spacing between adjacent, opposing catalytic walls of the fins) will be approximately 0.04 inch. The catalyst surface area per flowpath volume will be approximately 700 to 800 square feet per cubic feet (ft 2 /ft 3 ). 
         [0046]    The various reactants (i.e., JP-8, H 2 O and air) will be at a temperature of approximately 350° C. or greater prior to entry into the ATR and the product temperature upon exiting the ATR will be approximately 310° C. or less. The operating pressure of the ATR will be approximately 20 pounds per square inch absolute. 
         [0047]    Such an ATR, combined with a WGS reactor and a PROX reactor such as has been described above, will be capable of producing high purity hydrogen from JP-8, water and air with less than 10 parts per million (ppm) of carbon monoxide with the hydrogen being suitable for use in a PEM fuel cell. 
         [0048]    While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.