Abstract:
An apparatus includes a housing, a pullout drawer and at least one purification bed container. The housing is adapted to house at least one electrochemical cell, and the purification bed container(s) are mounted to the pullout drawer.

Description:
[0001]     This application claims the benefit under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 60/793,763, entitled “MODULAR FUEL BLOWER AND DESULFURIZATION DESIGN,” which was filed on Apr. 21, 2006, and is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND  
       [0002]     The invention generally relates to a modular fuel delivery subsystem for an electrochemical cell-based system.  
         [0003]     A fuel cell is an electrochemical device that converts chemical energy directly into electrical energy. There are many different types of fuel cells, such as a solid oxide fuel cell (SOFC), a molten carbonate fuel cell, a phosphoric acid fuel cell, a methanol fuel cell and a proton exchange member (PEM) fuel cell.  
         [0004]     As a more specific example, a PEM fuel cell includes a PEM membrane, which permits only protons to pass between an anode and a cathode of the fuel cell. A typical PEM fuel cell may employ polysulfonic-acid-based ionomers and operate in the 50° Celsius (C.) to 75° temperature range. Another type of PEM fuel cell may employ a phosphoric-acid-based polybenziamidazole (PBI) membrane that operates in the 150° to 200° temperature range.  
         [0005]     At the anode of the PEM fuel cell, diatomic hydrogen (a fuel) is reacted to produce protons that pass through the PEM. The electrons produced by this reaction travel through circuitry that is external to the fuel cell to form an electrical current. At the cathode, oxygen is reduced and reacts with the protons to form water. The anodic and cathodic reactions are described by the following equations:
 
H 2 →2H + 2 e   −  at the anode of the cell, and  Equation 1
 
O 2 +4H + +4 e   − →2H 2 O at the cathode of the cell  Equation 2
 
         [0006]     A typical fuel cell has a terminal voltage near one volt DC. For purposes of producing much larger voltages, several fuel cells may be assembled together to form an arrangement called a fuel cell stack, an arrangement in which the fuel cells are electrically coupled together in series to form a larger DC voltage (a voltage near 100 volts DC, for example) and to provide more power.  
         [0007]     The fuel cell stack may include flow plates (graphite composite or metal plates, as examples) that are stacked one on top of the other, and each plate may be associated with more than one fuel cell of the stack. The plates may include various surface flow channels and orifices to, as examples, route the reactants and products through the fuel cell stack. Several PEMs (each one being associated with a particular fuel cell) may be dispersed throughout the stack between the anodes and cathodes of the different fuel cells. Electrically conductive gas diffusion layers (GDLs) may be located on each side of each PEM to form the anode and cathodes of each fuel cell. In this manner, reactant gases from each side of the PEM may leave the flow channels and diffuse through the GDLs to reach the PEM.  
       SUMMARY  
       [0008]     In an embodiment of the invention, an apparatus includes a housing, a pullout drawer and at least one purification bed container. The housing is adapted to house at least one electrochemical cell, and the purification bed container(s) are mounted to the pullout drawer.  
         [0009]     In another embodiment of the invention, an apparatus includes a housing, a pullout drawer and a fuel blower. The housing is adapted to house at least one electrochemical cell, and the fuel blower is mounted to the pullout drawer.  
         [0010]     Advantages and other features of the invention will become apparent from the following drawing, description and claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0011]      FIG. 1  is a perspective view of a fuel cell system according to an embodiment of the invention.  
         [0012]      FIG. 2  is a perspective view of a modular delivery subsystem of the fuel cell system of  FIG. 1  according to an embodiment of the invention.  
         [0013]      FIG. 3  is a schematic diagram of the fuel cell system according to an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0014]     Referring to  FIG. 1 , in accordance with some embodiments of the invention, a fuel cell system  10  is housed inside a cabinet  20  (shown with its front panel removed in  FIG. 1 ), which serves as a housing for the system  10 . Among its various components, the fuel cell system  10  includes a fuel cell stack  50  and a modular fuel delivery subsystem  39 , which is mounted on a pullout drawer  40  that is slidably mounted with respect to the cabinet  20 . In this regard, the pullout drawer  40  is mounted on drawer guides (not depicted), which allow the drawer  40  to be extended (as depicted in  FIG. 1 ) and retracted with respect to the other fuel cell system components that are mounted to the cabinet  20 . More specifically, the drawer  40  may be extended from the cabinet  20  by grasping a knockout handle opening  94  that is formed in the drawer  40 , in accordance with some embodiments of the invention.  
         [0015]     Referring to both  FIGS. 1 and 2 , as described herein, the fuel delivery subsystem  39  is packaged in a way, which maximizes the serviceability of its desulfurization canisters, or cans  52  and  56 , and minimizes occupied space, cost and manufacturing time. More specifically, in accordance with embodiments of the invention described herein, the desulfurization cans  52  and  56  are closely packaged together with a fuel blower  60  and flow monitoring equipment  80  (all part of the fuel delivery subsystem  39 ) on the pullout drawer  40 , which permits accessibility to the subsystem after undoing only two mechanical connections: the natural gas inlet (which connects to an inlet  54  of one of the cans  52 , for example) to the fuel delivery subsystem  39  and a wire harness  84 .  
         [0016]     In accordance with some embodiments of the invention, the desulfurization cans  52  and  56  are associated with two desulfurization beds, such as Siliporite and Selexorb. For purposes of reducing the height of each purification module, two cans are provided for each of the absorption beds. For example, in accordance with some embodiments of the invention, the cans  52  may form a Siliporite purification bed, and the cans  56  may form a Selexorb bed.  
         [0017]     The cans  52  and  56  are serially connected, or plumbed, together. More specifically, the natural gas inlet to the fuel cell subsystem may be connected to a top connector  54  of one of the cans  52  so that natural gas flows from the top of the can  52  to its bottom. Plumbing (not shown) that is contained beneath a floor  92  of the pullout drawer  40  connects a bottom connection of the can  52  to the bottom connection of the other can  52 . Thus, natural gas flows through this other can from bottom to top to its top connection  54 . The top connection  54  of this can  52  may then be connected to the top connection  58  of one of the cans  56 . Similarly, the cans  56  are connected together at their bottom ends via plumbing that is present in the space  94  beneath the floor  92 .  
         [0018]     From the last can  56  in the serial connection, the natural gas flows to the fuel blower  60 . In this regard, the suction inlet of the fuel blower  60  may connected to the top outlet  58  of the last can  56  in the series so that the fuel blower  60  produces a flow that exits an exhaust port  90  of the fuel subsystem. As depicted best in  FIG. 2 , flow monitoring equipment  80  may be connected to the outlet of the fuel blower  60  for such purposes as monitoring the flow rate and pressure of the outgoing fuel flow. As specific examples, in accordance with some embodiments of the invention, the equipment  80  may include a pressure sensor and/or a flow metering device. Electrical cables that are used for such purposes as controlling, powering and receiving feedback from the equipment  80  and fuel blower  60  are connected via the wire harness  84 .  
         [0019]     Due to the compact design of the fuel delivery subsystem  39 , all fuel delivery parts may be easily pre-assembled, tested and leak-checked by a vendor and installed by manufacturing by simply sliding the pullout drawer  40  into place; and making the inlet and outlet natural gas connections; and connecting the wire harness  84 .  
         [0020]     Many variations are possible and are within the scope of the appended claims. For example, in accordance with some embodiments of the invention, fewer or more desulfurization cans  52  and  58  may be provided in accordance with other embodiments of the invention. For example, if the system footprint instead of the height were more important, the four desulfurization cans  52  and  56  may be replaced with two taller desulfurization cans (one to establish the Siliporite bed and the other to establish the Selexorb bed, for example).  
         [0021]     The advantages of the above-described modular fuel delivery subsystem  39  may include one or more of the following: 1.) the subsystem results in a true “module,” containing all fuel delivery parts; 2.) the subsystem may be pre-assembled, tested and leak checked by a vendor resulting in lower cost and higher reliability; 3.) in-house manufacturing may install the subsystem by simply setting it in place, connecting inlet, outlet and wire harness reducing manufacturing cost and increasing reliability; and 4.) the desulfurization cans system may be serviced by pulling out the drawer  40  from the cabinet  20  and changing the cans, thereby saving service time. Other and different advantages are possible, depending on the particular embodiment of the invention.  
         [0022]      FIG. 3  generally depicts a schematic diagram of the fuel cell system  10  in accordance with some embodiments of the invention. Natural gas flows through the desulfurization bed cans  52  and  56  and to the suction inlet of the fuel blower  60 . The fuel monitoring equipment  80  monitors the flow out of the desulfurization bed cans  56  and may be connected to a system controller (not depicted in  FIG. 3 ) of the fuel cell system  10  for purposes of monitoring the flow and controlling the reformer  120  and/or fuel blower  60  accordingly, in accordance with the various possible embodiments of the invention.  
         [0023]     The outlet of the fuel blower  60  furnishes a fuel flow to a reformer  120 , which produces a reformate flow to the fuel cell stack  50 . Among its other features, the fuel cell system  10  may include power conditioning circuitry  110  that converts the electrical output from the fuel cell stack  50  into the appropriate form for a load  200  to the fuel cell system  10 . For example, in embodiments of the invention in which the fuel cell system  10  provides power to a DC load, the power conditioning circuitry  150  transforms the DC stack voltage from the fuel cell stack  50  into the appropriate DC level for the DC load. Alternatively, in embodiments of the invention in which the load  200  is an AC load, the power conditioning circuitry  150  transforms the DC stack output from the fuel cell stack  50  into the appropriate AC voltage for the AC load. Additionally, it is noted that other variations are possible and are within the scope of the appended claims. For example, in other embodiments of the invention, the fuel cell system  10  may supply heat and not electrical power for a particular application. As another example, in another embodiment of the invention, the fuel cell system  10  may supply both electrical power and heat for a particular application.  
         [0024]     While the invention has been disclosed with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of the invention.