Patent Publication Number: US-2002006535-A1

Title: Integrated power module

Description:
[0001] of U.S. Pat. No. 09/512,727 which is a continuation of this application is a continuation of application Ser. No. 09/032,625 filed Feb. 27, 1998, which is a continuation-in-part of application Ser. No. 08/742,383 filed Nov. 1, 1996. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The present invention relates generally to a power module which produces electrical current as well as heat, and which can be used for various purposes, including driving a turbine or heating a dwelling or workplace. More specifically, the present invention is an integrated module that utilizes a partial oxidizing reactor (reformer) for producing hydrogen, which is subsequently used to generate electrical current by way of a fuel cell stack. Excess hydrogen and gas product may then be used to produce additional heat in a combustion chamber downstream of the fuel cell. Alternatively, the fuel cell can be substituted with an electrochemical reactor or diffusion membrane which is designed to further process the partial oxidation product gas for downstream equipment or to purify the product gas.  
       BACKGROUND OF THE INVENTION  
       [0003] In the generation and delivery of energy sources, including heat and electricity, to both small users in residential markets and large users in industrial markets, the control of pollution products, improved energy efficiency, and cost-effectiveness are increasingly acute concerns.  
       [0004] Prior attempts to address these concerns have typically involved large-scale, capital-intensive equipment and processes. For example, the prior art has endeavored to control pollution by using complicated equipment or cleaner-burning fuels at large energy facilities. Similarly, efficiency gains, which decrease primary energy consumption, have been realized through the staging of processes and the combining of energy cycles (eg., large combined-cycle power plants).  
       [0005] In larger industrial and commercial facilities, cogeneration systems have been used to provide the combined benefits of generating electrical energy on site and being able to recover and use by-product heat energy. However, such prior art technologies have generally not been cost-effective in small-scale systems. For example, fuel cell technologies offer exceptional efficiency and environmental benefits, but the high cost of fuel cell stacks in, low-volume production and the complexity of systems packaged with individual, discrete components have continued to prevent this technology from becoming cost-competitive. Larger scale systems have been developed in an attempt to decrease the impact of system complexities, but increased capital risk per unit of these plants has prevented sufficient demonstrations to verify benefits and improve durability and therefore has prevented high-volume production of such systems. In addition, relatively simple, small-scale fuel cell units which use pure hydrogen as a fuel source show some benefits, but the high cost of pure hydrogen and the lack of an extensive hydrogen distribution infrastructure have limited this approach.  
       [0006] Representative of the prior art is U.S. Pat. No. 3,516,807, in which a reaction chamber is provided with a mixing tube fed with air that has been heated in the exit of a combustion chamber. One of the purported objectives of this structure is to provide free hydrogen for use in a fuel cell. The structure relies, however, on a ducting or path arrangement which is likely to cause carbon or other kinds of deposits which will tend to rapidly accumulate and, consequently, retard or even stop the combustion process. This and other prior art devices have also typically failed to efficiently utilize the by-product heat from hydrogen production or to produce a sufficient quantity of electrical current as to be commercially usable.  
       [0007] Furthermore, attempts to address these problems, as well as others inherent in the use of non-polluting fuels, have often resulted in much greater expense in terms of the converting apparatus and the by-product handling equipment. The use of non-polluting or low-pollution-generating fuels has similarly resulted in much greater equipment expense, as well as more cumbersome controls than could be efficiently marketed to both industrial and residential users.  
       [0008] With the world&#39;s increasing population and improving standard of living, the need for electricity and heat is expected to grow substantially. Provision of such increased energy demands using the prior art&#39;s large central facilities and massive distribution infrastructures would be exceedingly capital-intensive. The availability of a small-scale, cost-effective, and non-polluting integrated power module capable of providing both electricity and heat using existing fuel sources can eliminate the need for massive capital investments in infrastructure and electric distribution facilities while incrementally providing the energy needs of developing populations.  
       SUMMARY OF THE INVENTION  
       [0009] The present invention obviates the foregoing problems and difficulties, and provides a combined source of heat and electrical power that is substantially pollution-free. In one form of the invention, a single, integrated module is provided, the module having simplified internal heat transfer and component integration to achieve a cost-effective system. Further, utilization of incoming fuel is staged to concurrently minimize emissions and maximize efficiency.  
       [0010] In accordance with one embodiment of this invention, such objectives are achieved in a small, modular power generator that can serve as an energy source for residential appliances, commercial equipment, and industrial processes. In a preferred embodiment, the stages of the unit are integrated thermally so that the inlet process gases provide cooling to various downstream components while also providing regenerative preheating for higher temperature upstream components.  
       [0011] In a preferred embodiment of the present invention, the staged consumption of fuel first involves a partial oxidation reformer which operates at a fuel-rich level (i.e., air/fuel stoichiometric ratio less than about 0.8) to create a hydrogen-containing gas stream that is subsequently processed by downstream stages. The air/fuel stoichiometric ratio in the reformer process is preferably between about 0.1 and 0.7, and is most preferably between about 0.2 and 0.4. The second stage is a stoichiometrically-balanced region, where fuel is reacted with oxygen electrochemically for high-efficiency conversion to electricity, without unwanted side reactions that create pollution in conventional combustion equipment. Finally, the third stage consumes any remaining fuel in a fuel-lean (i.e. air/fuel stoichiometric ratio greater than about 1.1) combustor. The air/fuel stoichiometric ratio in the third stage combustor is preferably above about 1.4. This third stage not only ensures the elimination of all non-reacted fuel, but also generates additional thermal energy which can be useful in a number of applications. The final stage does not create unwanted pollution (eg., thermal NO x ) because the hydrogen present in the fuel stream allows stable operation at these high stoichiometric ratios. In an alternative preferred embodiment, the second stage comprises a fuel cell for the generation of electrical current. In this alternative embodiment, a compression spring or a set of compression springs may be used to exert a mechanical force on the fuel cell.  
       [0012] A particular advantage of the present invention is the integrated design and structure of the power module that effects both preheating of the process gas and cooling of the product gas, as well as the components of the unit within the three stages, while minimizing interface complexities and equipment. According to one aspect of the present invention, cool inlet process gases enter the module and provide cooling to the fuel cell module and associated fuel cell compression hardware, while simultaneously providing preheating of the process gases for both the fuel cell and the reformer reaction, thereby increasing efficiency. As the inlet process gases progress toward the partial oxidation reformer, additional preheating is achieved in parallel with reformer product gas cooling. One embodiment would increase the air flow to achieve sufficient cooling of reformer product gases prior to introduction into the fuel cell. This excess air could then bypass the reformer and the fuel cell and enter into the fuel-lean combustion process. This would eliminate the need for water quenching. Evaporative water-to-steam quenching ultimately controls the fuel cell&#39;s anode process gas temperature.  
       [0013] Another advantage is the design of the partial oxidation reformer. Appropriate preheating and mixing of both the oxygen-containing gas (i.e. air) and the fuel gas are necessary to achieve stable operation and the generation of an appropriate amount of hydrogen gas for the downstream fuel cell and low emissions combustor. To this end, specifically-designed nozzles have been developed which, in combination with the appropriate preheating of the oxygen-containing gas after startup, will effect thorough and homogeneous mixing of the oxygen-containing gas and the fuel gas or vapor upon injection into the reaction chamber. Further, the design of the reaction chamber is such that the injected and mixed gases will be further mixed by impingement upon a wall (preferably, the rear or facing wall) of the reformer chamber, in a manner such as that disclosed in prior U.S. Pat. No. 5,229,536, the disclosure of which is incorporated herein by reference. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014]FIG. 1A is a cross-sectional block diagram illustrating the major components of an embodiment of the present invention and the process flow through the various components, and FIG. 1B is a cross-sectional detailed view of a preferred embodiment of the present invention;  
     [0015]FIGS. 2A, 2B,  2 C and  2 D are cross-sectional views of injector nozzle designs useful in the present invention;  
     [0016]FIGS. 3A and 3B are cross-sectional views of alternate embodiments of the reformer chamber of the present invention;  
     [0017]FIG. 4A is a cross-sectional view of one embodiment of the fuel cell stack and FIG. 4B is an elevational view of the fuel cell along line IVB-IVB of FIG. 1B. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0018] Referring now to the drawings, wherein like numerals designate corresponding parts, there is shown in FIG. 1 a  a cross-sectional block diagram illustrating the arrangement of major components of the integrated power module of the present invention, together with the flow path of the process air, the process fuel, and the product gas stream through the major components. As illustrated in FIG. 1A, the integrated power module comprises a housing  110 , in which reformer  116 , a fuel cell  118  and a combustor  120  are integrated into a single insulated assembly. The specific details of these components, as well as other features of the invention, will be described in conjunction with FIGS. lB through  4 B.  
     [0019] Referring in detail to FIG. 1A, inlet air  112  enter through inlet tube  113  at one end of the housing  110 , which housing may be of any desired shape, but is preferably cylindrical in shape for improved efficiency, lower cost, and simpler fabrication. The inlet air  112  moves along an outer, annular volume  114  which is in heat exchange relationship with a barrier in the form of one or more compression springs  124 . The compression spring or springs  124  surround the combustor  120  and are cooled by the inlet air  112 . The spring force of the compression spring(s)  124  is partially preserved by the cooling. The compression spring(s)  124  act between an end (preferably, the upper end) of the housing  110  and a compression plate set  133  and exert a mechanical force on the fuel cell  118 . preferably, the compression plate set  133  comprises individual plates  130 ,  131  and  132 , which are described in more detail in connection with FIG. 1B.  
     [0020] The inlet air  112  traveling along the annular volume  114  also effects cooling of the fuel cell  118  through flexible barrier wall  126 . Preferably, as illustrated in FIG. 1A, the fuel cell  118  is positioned below the combustor  120 . A portion of the inlet air  112  is diverted through orifice  128  to provide oxygen to the cathode manifold of the fuel cell  118 . The orifice  128  can be positioned at any suitable position between the top and bottom of annular volume  114  and may be of any appropriate shape so as to permit introduction and distribution of inlet air  112  into the fuel cell  118  at the appropriate flow rate and inlet temperature.  
     [0021] The remaining inlet air  112  which flows through the annular volume  114  and below fuel cell  118  will continuously absorb heat from (i.e. be preheated by) the product gas of reformer  116  through heat exchange wall  172 . Preferably, the inlet air  112  is preheated to at least 1000° F., and, most preferably is heated to between 1000 and 1800° F. (or higher) to enhance efficiency.  
     [0022] At least a portion of (i.e. all or a portion thereof) the inlet fuel  156  is supplied to the fuel injector  160  through a conduit  158  located at any suitable position on the housing  110 . The inlet fuel may comprise any combustible fuel or fuel/steam mixture. The conduit  158  is inserted in annular volume  114  so that the inlet fuel  156  is preheated through contact with either heat exchange wall  172  (which is in thermal contact with reformer product gas) or the now-preheated inlet air  112 , or both. The inlet fuel  156  is preferably preheated to between 500° F. and 1000° F. Other embodiments of conduit  158  are feasible, including a separate shell surrounding annular volume  114  or other means of preheating the inlet fuel  156  through contact with heat exchange wall  172  or preheated air in annular volume  114 .  
     [0023] The preheated inlet air  112  and inlet fuel  156  are introduced to the reformer  116  through a nozzle  169 , which comprises a fuel injector  160  and an air injector  22 , which are described in greater detail below. The inlet air  112  and the inlet fuel  156  become mixed upon injection into the reformer  116 . Various nozzle designs capable of providing air/fuel intermixing will be apparent to those skilled in the art. Examples of suitable nozzle configurations are discussed in greater detail in conjunction with FIGS. 2A, 2B,  2 C and  2 D. In addition, the fuel and the gas can be mixed prior to introduction into the reformer, such that the fuel injector and the air injector may be the same (eg. the nozzle may comprise a single injector for both fuel and gas).  
     [0024] Referring again to FIG. 1A, once the preheated inlet air  112  and inlet fuel  156  are injected through the nozzle  169  into the reformer  116 , partial oxidation combustion at a fuel-rich level (i.e. air/fuel stoichiometric ratio less than about 0.8) can occur. The air/fuel stoichiometric ratio is preferably between about 0.1 and 0.7 and most preferably is between about 0.2 and 0.4).  
     [0025] The air/fuel mixture is ignited (eg. by way of a spark plug) and, typically, reforming temperatures in the 2300-3000° F. range are achieved. Reformer product gases then pass out of the reformer  116  and into passage  168  and thereby heat the heat exchange wall  172 , which is in heat exchange relationship with annular volume  114 . The velocity of the gas in passage  168  is preferably maintained high to enhance heat transfer. Water and/or steam may be introduced through input  166  and injected into the reformer product gas in passage  168 ; input  166  may be placed at any suitable position. Input  166  may be in thermal contact with heat exchange wall  172  to facilitate evaporation of water in input  166  prior to injection into passage  168 . The water vapor thereby quenches the temperature of the reformer product gas stream. Preferably, the temperature of the reformer product gas is lowered to approximately 1300° F. based on fuel cell requirements and product gas stability.  
     [0026] The partially-cooled reformer product gas stream flows from passage  168  into the anode manifold of the fuel cell through channel  190  located in current collector wall  31 , which is positioned between the fuel cell  118  and the reformer  116 . Inlet air  112 , diverted at orifice  128  to the fuel cell  118 , enters the cathode manifold of the fuel cell. Preferably, the fuel cell is operated under stoichiometrically-balanced conditions, so that fuel is reacted with oxygen electrochemically to yield electricity with high efficiency, without unwanted side reactions that create pollution. The fuel cell  118  generates direct current which may be drawn off for external use through terminals  10  and  12 , which may be placed at any of various positions on the module as appropriate. The voltage and current output is dependent on the fuel cell area, number of cells, and performance.  
     [0027] The anode exhaust gas exiting the fuel cell  118  passes through exit passage  134  into combustor  120  after undergoing some temperature quenching by virtue of contact with the flexible heat transfer barrier wall  126 , which is in thermal contact with the relatively cooler inlet air  112 . The temperature of the anode exhaust gas is approximately 1500° F., but is dependent on the fuel cell type and performance, and the extent of heat transfer through flexible barrier wall  126  and water injected at input  166 . The cathode exhaust gas from the fuel cell  118  is directed to the combustor  120  through conduit  129  (shown in FIG. 4B).  
     [0028] The combustor  120 , described in greater detail below, is preferably operated at a fuel-lean level (i.e. air/fuel stoichiometric ratio above about 1.1; most preferably, above about 1.4). The combustor preferably includes a heat recovery device, such as a heat transfer coil  142 , to deliver the hear energy recovered from the process and/or generated by combustion to a downstream user or appliance. The exhaust gas  144  from the module passes out of the system through exhaust duct  141  (shown in FIG. 1B).  
     [0029] Referring now to a preferred embodiment of the present invention, as illustrated in FIG. 1B, the housing  110  is thermally insulated to minimize heat loss and to provide external thermal protection for users. Any of a variety of insulating materials can be used, including but not limited to fiberboards, foams, and/or blanks which are selected for their insulation properties and temperature compatibility. The housing  110  also includes a cover flange  111  which optionally can be removed for direct access to the combustor  120  and compression spring(s)  124 . Withdrawal of the combustor  120  and compression spring(s)  124  through the cover flange  111  permits access to and withdrawal of the fuel cell  118  and reformer  116 . Accessibility to the individual components of the integrated power module is useful for maintenance, inspection, and repair of the components, if necessary. In one embodiment, compression springs  124  are composed of materials which when heated expand in such a way as to increase the compressive force.  
     [0030] In this embodiment, compression spring(s)  124  provide mechanical force between the underside of the cover flange  111  and compression plate  130 , the topmost plate of the compression plate set  133  (shown in FIG. 1A), which plate set comprises plates  130 ,  131 , and  132 . the flexible barrier wall  126 , which can resemble a bellows, surrounds the fuel cell  118  and extends downward from the underside or the periphery of the compression plate set  133  to sealingly engage the current collector wall  31 , located above the reformer  116 . Preferably, a ring seal or weld is used to provide a gas-tight interface seal between the lower end of the flexible barrier wall  126  and the outer periphery of compression plate  130 . Similarly, a ring seal or weld provides a gas-tight seal between current collector wall  31  and (i) flexible barrier wall  126 , and (ii) heat exchange wall  172 . The compression spring(s)  124  and the flexible barrier wall  126  permit thermal expansion and contraction of the fuel cell  118  during operation of the module.  
     [0031] An electrical insulation plate  131  is positioned between compression plate  130  and current collector plate  132 . In FIG.  1 B, current collector plate  132  is positive (cathode side), but the stack polarity can be reversed, if desired. Positive terminal  10 , which is in electrical contact with current collector plate  132 , provides a user connection to the electrical current produced by the fuel cell.  
     [0032] As illustrated in FIG. 1B, the combustor  120 , is provided with an exhaust duct  141  attached to the cover flange  111  to direct exhaust gas  144  out of the module. The exhaust duct  141  can be moved with the cover flange  111  when the cover flange  111  is removed from the housing  110 . The bottom of exhaust duct  141  engages or interfaces with a perforated surface element  14 , which serves as the base for and defines the physical dimensions of the combustor  120 . Surface element  14  can be catalyzed to enhance spontaneous ignition or the combustion chamber  120  can be equipped with a spark ignition source (not shown). A removable heat transfer coil  142  located in the exhaust duct  141  is provided to recover heat for downstream or external use.  
     [0033] The reformer  116  in FIG. 1B is located proximate to the bottom of the integrated power module and is insulated thermally from a bottom seal plate  300 , which is supported against the base  162  at the bottom of the module assembly. A spark plug  174  extends into the reformer  116  through bottom seal plate  300  and the base  162  to provide ignition during start-up of the reforming combustion.  
     [0034] The housing  110  may optionally be provided with valved tubes  164  and  176 , which will serve to allow bleeding off of air from annular volume  114  or addition of additional air to annular volume  114 . These bleed tubes will allow adjustment of the air flow which may be required to control the amount of oxygen delivered to the reformer  116 , temperature of the preheated air  112 , and/or the level of cooling provided to the reformer product gas and the fuel cell  118 . These will be utilized to control the temperature and mass flow of the incoming air to provide the proper mixture at air injector  22 . Appropriate sensors may be employed within the annular volume  114  to control air valves  178  and  179  provided in the valved tubes  176  and  164 , respectively. Additionally, the housing  110  may be provided with an ancillary input  166  to supply steam or methane or a mixture of these to the passage  168 . Thus, the constituents of the gas products can be optimized prior to introduction to the fuel cell  118 .  
     [0035] In the embodiment illustrated in FIG. 1B, inlet process air  112  is introduced through inlet tube  113  into annular volume  114 , which is created by the space between the inside wall of the housing  110  and (i) the compression spring(s)  124 , (ii) the flexible barrier wall  126 , and (iii) the heat exchange wall  172 . The relatively cool inlet air  112  serves to cool the compression spring(s)  124 . A portion of the inlet air  112  is diverted through orifice  128  to provide oxygen to the fuel cell  118 . the diverted inlet air  112  ultimately flows through the fuel cell  118 , in which oxygen from the inlet air  112  is consumed. Typically, the temperature of the preheated air entering orifice  128  will be approximately 1000-1300° F., but the temperature will be fuel cell type dependent. The placement of orifice  128  can be at any appropriate position to achieve the desired temperature. An extension tube down along heat exchange wall  172  can be used to effect increased temperatures. The diverted, now oxygen-depleted air stream exits the fuel cell  118  and enters cathode outlet manifold  238  (shown in FIG. 4B), eventually passing through conduit  129  (shown in FIG. 4B) and through insulation plate  131  and compression plate  130 . The depleted air finally enters pre-combustion zone  16  and passes through port(s)  140  into the combustor  120 .  
     [0036] Below the fuel cell location, non-diverted inlet air  112  will pass in heat exchange relationship with heat exchange wall  172  to take up heat from and thereby cool the product gases in annular volume  168 . Inlet air  112  is preheated as a result of movement along the annular volume  114  and enters the reformer  116  through air injector  22  at a temperature of approximately 1000-1600° F., or even higher.  
     [0037] Concurrent with the air flow described above, inlet fuel  156  enter the module through conduit  158  and is preheated by heat exchange surfaces  159 , which are in thermal contact with heat exchange wall  172 . Preheated inlet fuel  156  is injected into reformer  116  through fuel injector  160 . Simultaneously, as described above, preheated inlet air  112  is injected into reformer  116  through air injector  22 . The inlet air and fuel begin to mix upon injection into reformer  116 , and are further mixed by impingement upon the rear wall  23  (top wall of reformer  116  in FIG. 1B), which faces the injectors and whose plane is transverse to the direction of the injected air and fuel. Such an approach is described in detail in U.S. Pat. Nos. 5,207,185, 5,529,484, and 5,441,546, the disclosures of which are incorporated herein by reference. This design results in enhanced mixing of fuel and air, which in turn results in enhanced combustion efficiency. FIG. 1B illustrates the process flow path  42  of the air/fuel mixture within the reformer  116 . Flow ring  170  promotes increased recirculation of the fuel/air mixture within the reformer  116  to enhance combustion and mixing.  
     [0038] Once combustion is initiated inside the reformer  116 , such as by spark plug  174 , burning will take place and the gas expansion and heat will cause expulsion of reformer product gases back through reformer port  20 . In the reformer  116 , partial oxidation reforming of the fuel occurs at a temperature typically within the range of 2300-3000° F.  
     [0039] Following partial oxidation combustion within the reformer  116 , reformer product gases exit through passage  168  which extends the length of the reformer  116  and enters the anode manifold of the fuel cell  118  through conduit  190 . Optionally, the reformer product gases may be temperature-quenched with water, steam, methane, or other fluid or gas from input  166  prior to introduction into the fuel cell  118 . Alternatively, catalyst can be disposed in passage  168  and a steam/fuel mixture can be introduced through input  166 , thereby promoting an endothermic steam reforming-type reaction that achieves the desired quenching effect. In the fuel cell  118 , reformer product gas carbon monoxide (CO) is converted into carbon dioxide (CO 2 ) and hydrogen (H 2 ) via a shift reaction. Water produced by the fuel cell  118  is vaporized and exits with the depleted fuel stream through exit passage  134  located in insulation plate  131  and compression plate  130 . The depleted fuel then enters the fuel distribution zone  18  and enters the combustor  120  through perforated surface element  14 .  
     [0040] As shown in FIG. 1B, the fuel cell  118  is equipped with terminals  10  and  12  to supply current to an external device. Electrical energy from the fuel cell  118  is collected in current collector wall  31  and flows through conductive flexible barrier wall  126  into compression plate  130 , where it subsequently passes into compression spring(s)  124  and into ground terminal  12  located on cover flange  111 . Ground terminal  12  can be located at any other appropriate location on the housing  110  which is in electrical contact with current collector wall  31 . The electrical energy then flows to a customer&#39;s load. Electrons from the customer load enter the positive terminal  10  and flow to the current collector plate  132 , where they are transferred back into the fuel cell  118 . Insulation layer  175  provides isolation of the positive terminal  10  from the grounded cover flange  111  and compression plate  130 . Insulation plate  131  provides electrical isolation between current collector plate  132 , compression plate  130 , and flexible barrier wall  126 .  
     [0041] The anode exhaust gas from the fuel cell  118  will be passed to combustor  120  through exit passage  134  at a temperature of typically 1500° F. to 1800° F., but this again will depend on the fuel cell type, performance, and the extent of heat transfer through flexible barrier wall  126 . The cathode exhaust gas will exit the fuel cell  118  and be passed also to combustor  120 , but through a conduit  129  (shown in FIG. 4B), again at approximately the same temperature.  
     [0042] Within the combustor  120 , depleted air from port(s)  140  and depleted fuel from perforated surface element  14  react and combust to liberate heat, which can be recovered by a downstream user or appliance through a heat transfer coil  142 . For example, the thermal energy recovered in this manner can be used to heat water that is then circulated through a residence or workplace to provide either hot water or heat, as needed. Finally, exhaust gas  144  exits the integrated power module through exhaust duct  141 .  
     [0043] In an alternative embodiment of the present invention, where the module is a liquid-fueled system, steam or a small amount of air may be introduced via tube  157  so that it becomes premixed with the inlet fuel  156 , thereby enhancing the reforming process and preventing particulate formation within the reformer  116 .  
     [0044] In another alternate embodiment, additional heat can be generated by enhancing combustion within the combustor  120  by adding air through conduit  138  to mix with the depleted air from conduit  129 , and/or adding fuel through conduit  136  to mix with the depleted air from exit passage  134 .  
     [0045] In yet other embodiments, increased control over characteristics such as the preheating temperature, process cooling, humidity and process stoichiometric composition/ratios can be achieved through various features or modifications. Examples of such features or modifications include: (i) passing additional air through inlet port  113  and/or withdrawing a portion of the inlet air  112  through air valve  178  and/or air valve  179  to enhance the cooling effect on the fuel cell  118  (this procedure also results in better control of the preheating temperatures for air entering the fuel cell through orifice  128 ); (ii) passing additional air into the module through air valve  178  to enhance the cooling effect of reformer product gases exiting in passage  168  or to better control the preheating temperature of the air entering the reformer  116 ; (iii) adding or removing air via air valve  179  to better control the preheating temperature of reformer air and the reformer stoichiometric ratios; and (iv) withdrawing air from air valves  178  and  179  and reinjecting the air into the module through conduit  138  to enhance heat recovery and overall efficiency. In sum, the performance of the integrated power module may be optimized by controlling one or more parameters by directing through the one or more valves, conduits, or inlets at least one process enhancer such as but not limited to an oxygen-containing gas, a combustible fuel, water (or steam), carbon dioxide, or air. The parameters which can be controlled include the inlet gas, the inlet fuel, the injected fuel, the injected gas, the reformer product gas, the fuel cell inlet gas, the anode exhaust gas, the cathode exhaust gas, the combustor inlet gas, and the combustor exhaust gas. Other features and modifications to improve the efficiency and performance of the integrated power module of the present invention will be apparent to those skilled in the art.  
     [0046] With reference now to FIG. 2A, there is shown an enlarged cross-sectional view of a coaxial nozzle  169  useful in the present invention. Specifically, the reformer port  20  at the entrance to the reformer  116  is defined by flow ring  170 , which may preferably have a thickness for from one-half to three inches in the direction of flow from the end of the injectors  160  and  22 . In this nozzle design, the fuel injector  160  comprises the inner volume of the coaxial nozzle, and the air injector  22  comprises the outer annular volume of the coaxial nozzle. The inlet fuel may comprise any suitable liquid or gaseous fuel, including but not limited to natural gas, ethanol, methanol, gasoline, kerosene, methane, and mixtures thereof with steam. The two injectors  22  and  160  are preferably coterminous at nozzle end  27 . With such an arrangement, the flow from nozzle end  27  will collapse on itself and enhance inlet air/fuel mixing prior to combustion. In addition, the nozzle end  27  of the fuel injector  160  and the air injector  22  is preferably located in a plane that is coplanar or lower relative to the reformer port  20  as shown in FIG. 2A. The positioning of the nozzle end  27  may be adjusted to achieve different reaction characteristics, if desired. The flow of reformer product gases is indicated by arrows. The reformer port  20  defined by flow ring  170  is of sufficient size to permit unimpeded injection of the fuel and air.  
     [0047] With reference to FIG. 2B, it will be seen that the nozzle is constructed from concentric tubes  23  and  24 , together with a central rod  25 . preferably, air is fed through air injector  22 , while fuel is fed through fuel injector  160 ; however, alternate combinations are feasible. The presence of the central rod  25  will enhance the gas mixing at the nozzle end  27 .  
     [0048] In the embodiment of FIG. 2C, the central rod  25  is replaced by a plug  25 , provided with a fuel passage  33  centrally therein. A deflector  29  is located in line with the axis of the fuel passage  33  and defines diverging fuel outlets  37 . The deflector  29  can be supported by struts (not shown) extending across the fuel outlets  37 . With this arrangement, a steam/fuel mixture is preferably supplied through injector  180  and air through air injector  22 , although these supplies can be interchanged. This configuration, with deflector  29  and with the appropriate dimensioning of the diameters of the tubes  23  and  24 , and with the appropriate pressure for the steam, creates a suction on the inlet fuel passage as the steam flows past fuel outlets  37 , thereby enhancing mixing and promoting vaporization at the exit end of the nozzle. Deflector  29  can also be constructed from a capped tube with holes providing fuel outlet  37 . Holes can also be added in tube  24  to allow air and fuel premixing prior to injection into reformer  116 .  
     [0049] In the embodiment of FIG. 2D, the central rod  25  is made of a tube  400  surrounding a spark igniter  402 , which replaces spark plug  174  of FIG. 1B. Spark igniter  402  is made from a conductive rod  404  and a non-conductive insulation sleeve  406 . Seal ring  408  is used as a pressure seal.  
     [0050] With reference now to FIG. 3A, there is shown an alternate embodiment of a reactor chamber  54 , the interior  56  of which serves as a combustion zone and which is provided with a helical tube  62  which receives a fuel gas through an inlet  58  and an oxygen-containing gas through an inlet  60 . The fuel and oxygen-containing gases are heated during their passage through the helical tube  62  to provide an intimate mixture, which is then injected into the chamber  56  through outlet  64 . The gases are further mixed by directly impinging on the rear wall  66  as shown. A sparking device  74  is provided to initiate ignition. The reaction products will then in turn heat the contents of the helical tube  62  before exiting through the outlet  68 . The foregoing structures are described in more detail in prior U.S. Pat. No. 5,299,536, the disclosure of which is incorporated herein by reference. It will be appreciated by those skilled in the art that the reaction chamber of FIG. 3A can be readily incorporated in place of reformer  116  of the FIG. 1B embodiment. The FIG. 3A embodiment is better for low-volume production. In FIG. 3B, a modification of the arrangement of FIG. 3A is shown where the fuel and air flows are maintained separate as heating of both flows takes place in separate helical tubes  62   a  and  62   b . In addition, a flow ring  70  is, positioned approximately coplanar with outlet  64  to enhance recirculation of the air/fuel mixture within the reformer. In these embodiments, the functional heat exchange walls  172  and  159  in FIG. 1B are replaced by the walls of components  58 ,  60 ,  62 ,  62   a  and  62   b . The function of conduit  190  in FIG. 1B is replaced by outlet  68 .  
     [0051] In general, the structures of the present invention are not limited in their applications by the scale of the parts although there may be a practical commercial upper limit for the fuel cells.  
     [0052] Referring now to FIGS. 4A and 4B, there are shown schematically two views of a fuel cell stack that can be usefully employed with the present invention It will be understood, of course, that other electrochemical converters can also be employed so long as these devices are capable of making use of the hydrogen generated by reformer  116 .  
     [0053] Further, while stacked rectangular plates are illustrated in FIGS. 4A and 4B, with external manifold areas defined by the intersection of the stacked corners with the inside surface of the flexible barrier wall  126 , it will be readily appreciated by those skilled in this technology that circular planar cells with internal manifolds or tubular arrays of cells could be fully employed with modifications to the placement of interface passages  190 ,  134 ,  128 , and  129 . In the illustrated form, corner seals  127  are required to separate the gas flows through the cell.  
     [0054] In FIG. 4A, a cathode plate series  180  and cathode gas passage  180   a  is interleaved with anode plate series  182  and anode gas passage  182   a , with the anode plates and cathode plates separated by suitable electrolytic layers  184  and a separator plate  302 . Due to the elevated temperature of the reaction gases, and the high hydrogen content on the anode plates and high oxygen content on the cathode plates, the following reactions will take place with a solid oxide fuel cell:  
     [0055] Anode H 2 +O═→H 2 O+2e −   
     [0056] Cathode  ½ O 2 +2e − →O═ 
     [0057] Overall →H 2 + ½ O 2 →H 2 O+electricity+heat  
     [0058] In the fuel cell  118 , the electrochemical reaction uses an electrolyte which is preferably a solid oxide or a molten carbonate, but other electrolyte layers are feasible that are electrically conducting and/or conduct positive or negative ions (i.e., are ionically conducting). Typically, such fuel cells operate at a temperature of 1000 to 1800° F. (600°-100° C). At these operating temperatures, water that is generated will be quickly evaporated and moved with the gas flowing out of the fuel cell. Any suitable porous metal oxides, conductive ceramics, or metal can, of course, be employed as the electrodes.  
     [0059] Preferably, with the combustor  120  operating at a fuel-rich stoichiometric ratio of greater than 1.4, the fuel cell exhaust anode and cathode gases can be fed to the combustor  120  and combusted. When maintained at a ratio greater than 1.4, combustion will occur with low emissions, in particular, low thermal NO x .  
     [0060] Steam may be provided in the reformer product gas flow to the anodes of the fuel cell stack to facilitate the reactions producing carbon dioxide, hydrogen and heat This will eliminate carbon monoxide in the fuel cell anode passages and thereby minimize objectionable pollutants.  
     [0061] Referring again to FIG. 1B, the anode off-gases will pass through exit passage  134  and can be mixed with additional methane or natural gas fuel through conduit  136  before being fed to the combustor  120 . This is useful particularly at start-up to be supplied through heat transfer coil  142  or when additional heat is needed by the user. Additional air can be supplied through conduit  138  and port(s)  140  to assist in complete combustion. The cathode off-gases are fed through a cathode outlet manifold  238  (as shown in FIG. 4B), located in compression plate  130 , into prechamber  16  and then to combustor  120 .  
     [0062] The current collector plate  132  will be connected on one face thereof to terminal  10  which is insulated by a ceramic collar  175 , which extends through the cover flange  111 . Above the current collector plate  132  is a ceramic insulation plate  131  which includes the anode off-gas exit passage  134 . A compression plate  130  is set atop insulation plate  131 . The fuel cell  118  is preferably surrounded by a conductive stainless steel flexible barrier wall  126 , which is impervious to air or gases and which is yieldable to accommodate expansion and contraction of the fuel cell  118  during operation of the module. Electrical isolation is achieved between flexible barrier wall  126  and the fuel cell plates by the corner seals  127 . The flexible barrier wall  126  will be provided with the oppositely-located orifice  128  (to receive incoming air from the air inlet  112 ) and conduit  129  (to allow exhaust of cathode off-gases from within the fuel cell).  
     [0063] It will also be understood that the reaction gas products from the partial oxidation reformer can also be employed in connection with a shift reactor to modify the gas products for discharge to the atmosphere or for other reactions. To this end, a shift reactor may be substituted for the fuel cell stack  118 .  
     [0064] In alternate embodiments of this invention, a shift reactor/hydrogen purification electrochemical reaction device replaces the fuel cell  118 . In such embodiments, the overall function of the system is to generate and purify hydrogen gas for use external to the system. In the embodiment illustrated in FIG. 1B, orifice  128  is connected to input  166  which provides steam to the cathode gas passages  180   a  (see FIG. 4A). The steam pressure in the cathode gas passages  180   a  is maintained greater than the process gas pressure in anode gas passages  182   a  to promote any cross-leakage to be steam and/or hydrogen from passages  180   a  back into anode gas passages  182   a , and not the other direction. Orifice  128  is not connected to inlet air  112 . The fuel cell hardware is operated as a hydrogen concentrator, which may require modifying the materials of construction of the cathode plates  180 . Such modification would be apparent to one skilled in the art. Current from an external source or power supply is used to force electron flow through the electrochemical device. For example, the following reaction takes place with a solid oxide electrolyte cell:  
     [0065] Anode H 2 +O═→H 2 O+2e −   
     [0066] CO +H 2 O→H 2+CO   2    
     [0067] Cathode H 2 O+2e − →H 2 +O═ 
     [0068] Overall H 2 O+CO→CO 2 +heat  
     [0069] H 2  mixed gas stream →H 2  in purified gas stream.  
     [0070] The net result is to promote the CO/H 2 O shift reaction to CO 2 and to move H 2  from the mixed gas stream in anode gas passages  182   a to cathode gas passages  180   a . In this embodiment, cathode outlet manifold  238  is connected to conduit  129 , but conduit  129  is not connected to combustion prechamber  16 . Conduit  129  is connected to the outside of housing  110  to provide purified and humidified hydrogen to some other use or appliance. In this embodiment, air is provided through conduit  138  to combustor  120  downstream of the electrochemical reaction device to facilitate combustion of any remaining hydrogen or carbon monoxide that exhausts the shift reactor/purification electrochemical device through passage  134 .  
     [0071] In another embodiment of the hydrogen generation/purification system, a small amount of inlet air  112  can be combined with steam from input  166  prior to entering orifice  128 . This mixture passes into cathode gas passages  180   a , where the oxygen reacts on the cathode surfaces generating potentials that drive the hydrogen concentration process discussed above. The external electrical connections are used to extract or supplement energy needed by the electrochemical device.  
     [0072] In another embodiment of the hydrogen generation/purification system, the device  118  is constructed of metal and/or ceramic diffusion membranes that are porous to hydrogen but not to other gases in the mixed gas stream, such as nitrogen, carbon dioxide, and carbon monoxide, among others. These diffusion membranes consist of two sides (i.e., a mixed gas side and a purified product gas side), and can be supported or unsupported by porous ceramic structures. Because the diffusion membrane is porous to hydrogen gas, but not the other components of the mixed gas stream, only hydrogen gas is able to diffuse through the membrane from the mixed gas side to the purified product gas side. The membranes would replace electrolytic layers  184  and separator plate  302  of the fuel cell, and cathode plates  180  and anode plates  182  would be eliminated. A surface coating can be added to the membrane surface in anode gas passage  182   a . In this embodiment, the partial pressure of the hydrogen gas in the mixed gas stream in the anode gas passage  182   a  drives the movement of hydrogen through the membrane and into the cathode gas passage  180   a . purified hydrogen flows through conduit  129  and out of the housing  110 . Steam from input  166  flows through orifice  128  and into cathode gas passage  180   a . The pressure of the steam in the cathode gas passage  180   a  is maintained greater than the pressure of the mixed gas stream in anode gas passage  182   a . This steam has two critical functions. The first function is to ensure any cross-leakage that may occur is from cathode gas passage  180   a  into anode gas passage  182   a , thereby maintaining product gas purity in passage  180   a . The second function is to decrease the hydrogen partial pressure in cathode gas passage  180   a  with water vapor that is easily separated and removed downstream by use of a condenser. With counter-flow directions of the mixed gas stream in anode gas passage  182   a  and steam/purified hydrogen in cathode gas passage  180   a , a positive hydrogen partial pressure driving force can be maintained even with extremely high recovery factors (for example, most if not all the hydrogen is moved from the mixed gas stream in anode gas passage  182   a  to the purified hydrogen stream in cathode gas passage  180   a ).  
     [0073] As described above, the present invention provides several embodiments that have a wide range of applications, as scaling of the configurations can be readily accomplished by those skilled in the art to provide the necessary heat, electrical energy, and/or purified hydrogen output for a particular application. Various modifications and equivalent substitutes may be incorporated into the invention as described above without varying from the spirit of the invention, as will also be apparent to those skilled in this technology. In addition, while particular terminology is used in the foregoing description to describe certain aspects and elements of the present invention, one skilled in the art would understand that other equivalent descriptive terms may be substituted therefor. For example, the term “air” is used herein, for convenience sake, to refer to any oxygen-containing gas suitable for use in the integrated power module. Furthermore, the Examples presented herein are intended for illustration purposes only and are not intended to act as a limitation on the scope of the following claims.