Abstract:
There is described a fuel cell power system including a fuel processor subsystem, a fuel cell subsystem, and a power conditioning subsystem. The fuel processor subsystem comprises a main module for producing hydrogen rich streams from a hydrocarbon fuel, a balance of plant module for auxiliary components, and a control and electronic module for monitoring and controlling the fuel processor subsystem. The fuel cell subsystem comprises a main module for generation of electric power and thermal energy from hydrogen rich streams produced by the fuel processor module and air, a balance of plant module for auxiliary components, and a control and electronic module for monitoring and controlling the fuel cell subsystem. Each module has individual components attached thereto, the modules being designed and manufactured separately and assembled together to form the respective subsystems.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of U.S. patent application bearing Ser. No. 11/061,739, filed on Feb. 22, 2005, which is related to commonly assigned pending U.S. patent application entitled “Integrated Fuel Cell Power Module”, filed on Sep. 24, 2004 and bearing Ser. No. 10/948,794, the contents of which are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to devices which produce an electrical current by means of a chemical reaction or change in physical state, and more specifically, electrochemical fuel cell power generation systems comprising multiple subsystems including fuel processing, fuel cell stack, power conditioning, electronics and controls as well as the components of balance of plant. 
     BACKGROUND 
     Fuel Cells (FC&#39;s) are electrochemical devices that directly convert the chemical energy of a fuel into electricity. In contrast to energy storage batteries, fuel cells operate continuously as long as they are provided with reactant gases. In the case of hydrogen/oxygen fuel cells such as proton exchange membrane fuel cells, which are the focus of most research activities today, the only by-product is water and heat if pure hydrogen is used. The high efficiency of fuel cells and the prospects of generating electricity without pollution have made them a serious candidate to power the next generation of vehicles, houses and mobile devices. More recently, focus of fuel cell development has extended to remote power supply and applications, in which the current battery technology reduces availability because of high recharging times compared to a short period of power supply (e.g. cellular phones). 
     There are basically three major applications of fuel cells, namely, transportation, stationary and portable powers. In the case of transportation applications, pure hydrogen appears to be the most desirable fuel rather than on-board hydrogen production from hydrocarbon fuels, given the factors such as complexity, cost and slow start-up. This suggests that a fuel cell power system without fuel processing is most appropriate for transportation applications. In the case of stationary applications, especially in the low power range (&lt;10 kW), two types of application, i.e. residential and backup power (or uninterruptible power units) are typical, with the former being generally installed with both a fuel processor and a fuel cell power system, and the latter only a fuel cell power system. Depending on the applications, fuel cell manufacturers have been putting their resources on either transportation, residential or backup. The products developed and manufactured in such cases cannot be transferable, i.e. each product requires a separate, lengthy and costly process of development, manufacturing and assembly. 
     Still, one of the most important issues impeding the commercialization of fuel cells is the cost. Besides the material, the complexity in the present designs shares a significant portion of the high cost. As it is well known in the field, a fuel cell power plant commonly comprises of hundreds (if not thousands) of components, with all of these components being properly connected, integrated, and housed in a chamber. It is a common feature that these multiple components have been made to best utilize the space inside the chamber in order to make the fuel cell system more compact. However, this feature has led to poor manufacturability, poor accessibility for assembling and poor serviceability. It is often the case that the whole system or subsystem (such as fuel processor, fuel cell stack) must be replaced even though there is only one part that has actually failed. 
     SUMMARY 
     It is therefore an objective of the present invention to provide a fuel cell system and a method to design and manufacture the same. 
     According to the present invention, the fuel cell system will be suitable as a stand-alone product for hydrogen production, pure hydrogen based transportation and backup power systems and fossil fuel residential applications as a result of disclosed modular design features. The functionally grouped and mechanically integrated modules can be separately manufactured, and serviced. Once manufactured, these modules can be easily installed and integrated to form a fuel processor, a fuel cell backup power system, or a residential fuel cell combined heat and power system. It provides the great degree of flexibility in manufacturing, assembly, and service. Each module can be easily replaced once it fails without sacrificing the entire system. 
     While this invention will be discussed mostly in relation to a Proton Exchange Membrane Fuel Cells (PEMFC), operated at either commonly referred low-temperature (e.g. &lt;100° C.) or high-temperature (e.g. 120-250° C.) conditions, it is also applicable to other types of fuel cells such as alkaline fuel cell (AFC), phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC), and solid oxide fuel cell (SOFC). 
     The present invention discloses a fuel cell system that is comprised of functionally grouped and mechanically integrated modules at all levels of system, subsystem and components, with the objective to increase the manufacturability, assembling ability and serviceability. Another objective is to increase the simplicity, and compactness of fuel cell systems. Yet another objective is to reduce the costs associated with fuel cell manufacturing, assembly, maintenance and service. Still another objective is to provide a method that allows quick development of various fuel cell products, e.g. fossil fuel residential or stationary CHP units, direct hydrogen fueled backup power units, and hydrogen production fuel processor. 
     The fuel cell power generation system is an integrated package from some or all of four major subsystems including fuel process subsystem, fuel cell subsystem, power conditioning subsystem and heat recovery subsystem. Furthermore, the fuel processor subsystem consists of three modules: fuel processor module, balance of plant module and electronics and controls module. Similarly, the fuel cell subsystem is made of three modules: fuel cell module, balance of plant module and electronics and controls module. The fuel processor module and fuel cell module each contain several separately manufactured and serviceable component modules, which are appropriately integrated. Linkage between the modules can be flexible and/or quick-connectable type. All the modules from component, subsystem to system are designed and constructed separately, and once manufactured they are linked or somehow stacked together according to the flow scheme to form an integrated compact device. The modular design feature as presented in this invention allows ease of manufacturing, leak testing, assembling and maintenance. It also allows repairing or replacing individual modules easily and cost effectively, once a failure has been detected. 
     In accordance with the present invention, there is provided a fuel cell power system including a fuel processor subsystem, a fuel cell subsystem, and a power conditioning subsystem. The fuel processor subsystem comprises a main module for producing hydrogen rich streams from a hydrocarbon fuel, a balance of plant module for auxiliary components, and a control and electronic module for monitoring and controlling the fuel processor subsystem. The fuel cell subsystem comprises a main module for generation of electric power and thermal energy from hydrogen rich streams produced by the fuel processor module and air, a balance of plant module for auxiliary components, and a control and electronic module for monitoring and controlling the fuel cell subsystem. Each module has individual components attached thereto, the modules being designed and manufactured separately and assembled together to form the respective subsystems. 
     In accordance with a second broad aspect, there is provided a fuel cell power system including a fuel processor module, a fuel cell module, and a power conditioning module, wherein a balance of plant module regroups all system balance of plant components and is separate from the fuel processor module, fuel cell module, and power conditioning module; and an electrical and control module regroups all electrical and control devices to control and operate the system and is separate from the fuel processor module, fuel cell module, and power conditioning module. 
     In accordance with a further broad aspect, there is provided a fuel cell power system including a fuel processor subsystem, a fuel cell subsystem, and a power conditioning subsystem, characterized in that: the fuel processor subsystem comprises a first main module for producing hydrogen rich streams from a hydrocarbon fuel, a first balance of plant module for auxiliary components, and a first control and electronic module for monitoring and controlling the fuel processor subsystem, the first main module, the first balance of plant module, and the first control and electronic module being physically regrouped together; and the fuel cell subsystem comprises a second main module for generation of electric power and thermal energy from hydrogen rich streams produced by the fuel processor module and air, a second balance of plant module for auxiliary components, and a second control and electronic module for monitoring and controlling the fuel cell subsystem, the second main module, the second balance of plant module, and the second control and electronic module being physically regrouped together, the fuel processor subsystem and the fuel cell subsystem being physically disposed separately from one another within the fuel cell power system; each the module having individual components attached thereto, the modules being designed and manufactured separately and assembled together to form the respective subsystems, each the module removable from the fuel cell power system as a single unit independently. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which: 
         FIG. 1 . is a block diagram of the fuel cell power generation system in accordance with a preferred embodiment of the present invention; 
         FIG. 2   a  illustrates the separate modules that make up the fuel processor subsystem in accordance with a preferred embodiment of the present invention; 
         FIG. 2   b  illustrates the separate modules that make up the fuel processor subsystem in accordance with another preferred embodiment of the present invention; 
         FIG. 3   a  illustrates the separate modules that make up the fuel cell subsystem in accordance with a preferred embodiment of the present invention; 
         FIG. 3   b  illustrates the separate modules that make up the fuel cell subsystem in accordance with another preferred embodiment of the present invention; 
         FIG. 4  illustrates the separate modules that make up the power conditioning subsystem in accordance with a preferred embodiment of the present invention; 
         FIG. 5  illustrates the separate modules that make up the heat recovery subsystem in accordance with a preferred embodiment of the present invention; 
         FIG. 6  illustrates the modular design at the component level for the fuel processor subsystem in accordance with a preferred embodiment of the present invention; 
         FIG. 7  illustrates the modular design at the component level for the fuel cell subsystem in accordance with a preferred embodiment of the present invention; and 
         FIG. 8 . is a block diagram of the fuel cell power generation system for a high-temperature system in accordance with a preferred embodiment of the present invention. 
     
    
    
     It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows a fuel cell power system  10  comprising of four major subsystems, namely, a fuel processor subsystem (FPS)  20 , a fuel cell subsystem (FCS)  30 , a power conditioning subsystem (PCS)  40  and a heat recovery subsystem (HRS)  50 . If designed and manufactured separately, FPS  20 , FCS  30  and PCS  40  can be independent devices for hydrogen production and pure hydrogen based fuel cell power generators. When combined in a way such as shown in  FIG. 1 , it becomes an integrated fossil fuel based fuel cell power system for either small or large stationary applications. When they are further integrated with HRS  50 , it can provide both heat and power for users. This provides a modular design at the system level. 
     For the fuel processor subsystem module, as schematically illustrated in  FIG. 2   a  and  FIG. 2   b , it further consists of four general sub-modules, namely,
         a fuel processor module  21 , in which all fuel processor sub-components such as steam reformer, shift reactor, desulfurizer, preferential oxidation reactor (PROX) and heat exchangers are independently manufactured, and interconnected according to the fuel processing flow and thermal management in a preferably compact fashion;   a fuel processor balance of plant module  22 , which is a platform on which all the auxiliary components in relation to the fuel processing, such as hand valves, solenoid valves, pressure regulators, check valves, compressors, flowmeters, and filters, are installed and connected. There are also connecting ports in predetermined locations for quick connections of streams from the supply sources and to the above mentioned fuel processor module  21 ;   an electrical module  23 , which controls and coordinates the fuel processor operation by collectively installed all electrical devices such as I/O boards;   a control module  24 , which monitors and controls the fuel processing subsystem operation, including data acquisition and display (GUI).       

     On FPS  20   a , there is a fuel stream  100  supplying the fuel (e.g. natural gas, liquefied petroleum gas), and a water stream  300  for use in hydrocarbon reforming. Air  200  is shown here only for illustration purposes because it will actually be taken from surrounding space. There is another stream, anode off gas recycling stream  190 , which supplies the majority of burning fuel for the fuel processor in the case that the fuel processor is part of the fuel cell power system. In the case of stand-alone, this stream will be compensated by a burning fuel stream which is generally the same as, and will be split within the fuel processor balance of plant module  22  from, fuel  100  supplied to the reformer. In case of cogeneration applications, the cogeneration water  360  from HRS  50  can be supplied to the FPS  20  to recover the available heat from combustion flue gases. All incoming fluid streams ( 100 ,  200 ,  360 ,  190 ,  300 ) and exhausting streams (hydrogen rich reformate stream  180 , flue gas  240 , warm cogeneration water  370 , and water condensate  600 ) are connected to and from the ports on fuel processor balance of plant module  22  of FPS  20   a . Fluids are fluidly communicating between fuel processor module  21  and balance of plant module  22  by means of quick connectable, either rigid or flexible tubes between ports  21   a  and  22   a  (i.e. hydrocarbon fuel  101 , anode off gas  191 , air  201 , cogeneration water  361 , deionized water  301 , reformate  179 , flue gas  239 , warm cogeneration water  369 , water condensate  599 ). The electric power  430 , preferred as DC power, used to operate the electrical components collectively installed on electrical module  23  and controllers  24  of FPS  20  can be either supplied from an external power source (FPS stand-alone) or from the PCS  40  that converts and conditions the DC power output from the fuel cell stack (FPS integrated with FCS and PCS). Part of the electrical power  432  is supplied to operate the fuel processor balance of plant components on  22  that require electrical power such as solenoid valves, air blowers, compressors, and electrical heaters. And the rest of electrical power  431  is supplied to fuel processor control module, which may receive a control signal  500  from, and send a control signal  505  to the central control system of fuel cell system  10 . The control signals  501  and  504  can be passed between fuel processor control module  24  and fuel processor electrical module  23 , and signals  503  and  504  can be passed between fuel processor electrical module  23  and fuel processor balance of plant module  22 . 
       FIG. 2   b  illustrates an alternative to  FIG. 2   a , in which the exhausting streams are directly connected from fuel processor module  21  of FPS  20   b . This may be advantageous over  20   a , because the fluid communication between fuel processor module  21  and fuel processor balance of plant module  22  can be simpler. 
     The produced hydrogen rich gas  180  can be used in any way, or directly supplied to a fuel cell power subsystem  30  ( 30   a  or  30   b ). As for FPS  20 , the FCS  30  can also be made up of four independently manufactured sub-modules, namely,
         a fuel cell module  31 , which is an entirely integrated compact assembly including at lease one fuel cell stack, at least one fuel cell heat exchanger, a fuel cell stack cooling loop with a coolant expansion tank and a coolant filter, at least one cathode blower, and necessary water condensate drainage valves. All these components are mechanically manufactured and integrated in a preferred compact fashion;   a fuel cell balance of plant module  32 , which is a mechanical platform on which all necessary auxiliary components (such as valves, regulators, pumps, etc.) to make the fuel cell module operable and functional are collectively installed. There are also connecting ports in predetermined locations for quick connections of streams from the supply sources and to the fuel cell module  31 ;   a fuel cell electrical module  33 , a mechanical platform where all electrical and control devices such as power supplies, switches, delays, and I/O boards, are collectively installed, and   a fuel cell control module  34 , which monitors and controls the fuel cell subsystem operation, including data acquisition and display (GUI).       

     In case of direct hydrogen systems, the stream  180  can be replaced by a pure hydrogen source. Again, an air stream  250  to cathode of the fuel cell stack is shown here only for illustration purpose. The water stream  370 , flowing from either the FPS  20  or directly from HRS  50 , enters the FCS  30  to remove the heat produced by the electrochemical reactions of fuel cells. The incoming fluid streams  180 ,  250  and  370  are supplied to fuel cell subsystem  30  by means of quick connectable, rigid of flexible, tubes to ports on fuel cell balance of plant module  32 , from where they are sent to fuel cell module  31  by collecting either rigid or flexible tubes  181 ,  251 , and  371  between ports  31   a  and  32   a . A stack coolant stream,  700  and  701 , may flow between fuel cell module  31  and fuel cell balance of plant module  32 . The residue fuel  182  flowing out the fuel cell stack  31  is sent to fuel cell balance of plant module  32 , from where it can be discharged or recycled to fuel processor subsystem  20  as anode off gas stream  190 . The fuel cell module generally includes a fuel cell stack having a plurality of fuel cells, at least one heat exchanger to transfer fuel cell produced heat to cogeneration water, and possibly humidifiers for humidifying fuel stream and/or cathode air. The fuel cell balance of plant module generally includes all components such as air blowers, pumps, filters, and solenoid valves necessary for operating fuel cell system. The warmed water  380 , which connects to stream  379  from fuel cell module  31 , flows out the fuel cell balance of plant module  32  of FCS  30  and returns to HRS  50  while useful heat can be utilized in any appropriate way by, for instance, flowing water streams  350  and  390 . On the FCS  30 , there is still another output port for discharging a water condensate stream  601  that may be produced in fuel cell module  31  and flows as stream  602 . The DC power  400  produced is generally subject to a converter and power conditioner PCS  40 . The electric power  420  used to operate the electronics collectively installed on fuel cell electrical module  33  and controllers collectively installed on fuel cell control module  34  of FCS  30  is generally supplied from the PCS  40 , which produces the power  440  for end users. The electrical power  421  and  422 , required by the fuel cell control module  34  and fuel cell balance of plant module  32  respectively, are supplied from fuel cell electrical module  33 . There may be electrical power supply  423  to the fuel cell module  31 . The fuel cell control module, when stands alone, sends to, and receives from, fuel cell electrical module  33  the control signals  511  and  514  to control operations of electrical components there. Similarly, there may have control signals  512  and  513  between fuel cell electrical module and fuel cell balance of plant module for control electrical components operation. 
     Similarly, the fuel cell subsystem  30  can be constructed as other alternatives to one illustrated in  FIG. 3   a . One of such alternatives is illustrated in  FIG. 3   b , in which the output of the fluid streams from fuel cell subsystem can be from the fuel cell module  31 . 
       FIG. 4  illustrates a modular power conditioning subsystem  40 . On PCS  40 , it first has a control module  46  which controls the PCS operation. The control module  46  may be communicating with a centralized control system of fuel cell system  10  by receiving a control signal  520  and sending a control signal  535 . The control module  46  also sends to, and receives from the electrical module  45  the control signals  521  and  522 . There is also an electrical module  45  which collectively installs all electronic devices such as I/O boards, power sources and switches. Interacting with the PCS control module  46  and electrical module  45 , there generally have three modular components, namely:
         a DC/AC converter module, which converts the fuel cell produced DC power into AC power for end use. The DC/AC converter module may have an electrical input  441  and an electrical output  446 , and it may receive a control signal  523  and send a feedback control signal  524 .   a DC/DC converter module, which converts the fuel cell produced unregulated DC power to regulated DC power, which is then possibly used for fuel cell system auxiliaries. The DC/DC converter module may have an electrical input  442  and an electrical output  443 , and it may receive a control signal  525  and send a feedback control signal  526 .   an AC/DC converter module, which will convert the AC power from commercial grid to regulated DC power for use of fuel cell system auxiliaries. The AC/DC conversion is often necessary during fuel cell system start up when there is no electrical power production from fuel cell system. On the AC/DC converter module, there may have an electrical input  447  and an electrical output  445 , and it may receive a control signal  527  and send a feedback control signal  528 .       

     On PCS electrical module  45 , there is generally a DC electrical power input port to receive the fuel cell produced DC power  440 , and another input port to receive the AC power  450  from commercial grid. There is also an output port to deliver the converted AC power  400  for end use, and another output port for the regulated DC power  410 , either converted from fuel cell produced DC power or from commercial grid AC power. 
       FIG. 5  shows a modular design of heat recovery subsystem according to one of the preferred embodiments of the present invention. The HRS  50  can generally be constructed by assembling several independently manufactured sub-modules, namely:
         a heat recovery control module  55 , which controls the HRS operation by collectively installed devices for data acquisition and display. The control module  55  may receive a control signal  540  from, and send a control signal  550  to, a centralized control subsystem of fuel cell system  10 . The control system  55  is powered by preferably a DC power  411  supplied from an electrical module  54 , and it may send a control signal  541  to, and receive a control signal  542  from the electrical module  54 .   an electrical module  54 , which collectively houses all electronic devices for operating the HRS  50 . The electrical module  54  is powered by preferably a DC power  410 , and outputs a portion of the power  411  to the control module  55  and another portion  412  to a heat recovery balance of plant module  53 . On the module  54 , there may be input ports and output ports for sending and receiving control signals  541  to  544 .   a heat recovery balance of plant module  53 , which is a platform to house, install all necessary auxiliaries such as valves, pumps and regulators in order to make the HRS  50  functionally operational. The hot water stream  380  from the fuel cell system  10  returns to the heat recovery balance of plant module  53 , from where it further flows to a heat storage module (generally a thermal storage tank)  52  by collecting the stream  381 . The circulation cogeneration water  382  from the storage module  52  is send back to the fuel cell system via the heat recovery balance of plant module  53  as water stream  360 . Between the heat recovery balance of plant module  53  and the heat storage module  52  there may have control signals  545  and  546  for operation control;   a heat storage module  52 , which generally is a water storage tank in which the heat recovered by the HRS is temporally stored. Whenever there is a thermal demand from the end use, the heat stored will be withdrawn by supplying a hot water stream  350 . A city water stream  390  may be supplied to the storage module to make up the water withdraw in any preferred method;   a supplementary heat production module  51 , which, in most cases, includes a supplementary gas burner, and may preferably be integrated with the heat storage module  52 . The supplementary heat production module  51  is generally provided to supply the heat demands that are beyond the thermal production capacity of fuel cell system  10 , or that are not available during the moments of fuel cell operations. A city water stream  390 , a fuel stream  102 , and an air stream  202  can be supplied to the supplementary heat production module  51  for heat production.       

     Now referring further to  FIGS. 6 and 7  for the concepts of modular design at subsystem levels. In  FIG. 6 , the fuel processor subsystem FPS  20  is made of four modules, i.e. fuel processor module  21 , a balance of plant panel module  22  and a fuel processor related electrical module and a control module (not shown). All these modules can be manufactured separately, and once finished they can be simply integrated by quick connections. The fuel processor module  21  is preferably a mechanically integrated, compact fuel processor with only input (QC- 109  to QC- 114 ) and output ports (QC- 115  to QC- 117 ) for fluids. As will be described later, the fuel processor  21  generally consists of multiple devices such as reformer, burner, steam generator, water-gas shift reactor, preferential oxidizer and heat exchangers, which are all connected and integrated inside the fuel processor module  21 . One will only view the input ports and output ports for streams of hydrogen rich gas  180 , combustion flue gas exhaust  240  and warmed cogeneration water  370 . On the fuel processor balance of plant panel module  22 , all fuel processor accessories such as valves, flow meters, filters, check valves, pressure regulators, compressors are preferably arranged in a two-dimensional fashion. The components on the panel  22  can be connected preferably by flexible tubing. The panel  22  holds all components of the balance of plant and the collecting ports for accepting input streams of fuel  100 , anode off gas recycling  190 , cogeneration water  360  and water to boiler  300 . It also has the connectors for connection of gas streams to the fuel processor module  21  through preferably flexible tubing  101  for fuel,  191  for anode off gas recycling,  201  for burner air,  210  for PROX air,  361  for cogeneration water and  301  for water to boiler. All the ports are preferably of the quick-connection type, which allow quick and easy installation. The modules  23  and  24  contain all power electronics and controls, connecting to the panel  22  by preferably a cable and interface connectors. 
     Similar to fuel processor subsystem module shown in  FIG. 2 , fuel cell subsystem module  30 , as shown in  FIG. 7 , is further divided into three modules: fuel cell module  31 , the module of balance of plant  32  and fuel cell electronics and controls modules  33  and  34 . Again, all these modules can be manufactured separately, and once finished they can be simply integrated by quick connections. The fuel cell module  31  is preferably a mechanically integrated, compact subsystem with only input and output ports for fluids, and inside there are sub-modules of fuel cell stack, humidifier, heat exchangers, coolant tank and coolant circulation pump. However, only the input connection ports and output ports can be seen. On the balance of plant panel module  32 , all fuel cell accessories such as valves, pressure regulators, air blowers (compressors) are preferably arranged and installed in a two-dimensional fashion. The hydrogen or hydrogen rich reformate  180 , nitrogen (used for stack purging generally)  310 , and the cogeneration water  370  are connected to the panel  32 , and after proper flow arrangement they, together with the cathode air  251  and cooling air  260 , are sent to the fuel cell module  31  through the connection ports  32   a  on the panel  32 . All the ports are preferably of the quick-connection type, which allow quick and easy installation. The modules  33  and  34  contain all power electronics and controls, connecting to the panel  32  by preferably a cable and interface connectors. 
     The modular design concept at subsystem level described above can be further illustrated in  FIGS. 6 and 7 , which demonstrate the modular design concept at component level. It should be understood that they are provided here only for illustration purpose and in practice, the flow arrangement and the involved components can be determined by the actual process and application characteristics, which are beyond the scope of this invention. 
       FIG. 6  shows one example of the embodiments according to the present invention with regard to the fuel processor module  21  and its balance of plant module  22 . As already mentioned earlier, there are for input ports on the module  22  to be connected to the external streams: QC- 100  for fuel  100 , QC- 101  for anode off gas recycling  190 , QC- 102  for water to boiler  300  and QC- 103  for cogeneration water  360 . A hand valve HV- 100  is positioned right after the fuel is entered through QC- 100 , which will be manually opened or shutdown for security needs of system operations. Fuel is passed through a dust filter FL- 100  before flowing through two successively installed solenoid valves SOV- 100  and SOV- 101 , which in this case are installed based on safety regulations, and will be actually controlled by a regulatory recognized reliable electronic controller (not shown). The fuel is then split into two streams; one is to be sent to the reformer as feed, and the other to be supplied as supplementary fuel to anode off gas as burner fuel. On the feed line, there may be installed a solenoid valve SOV- 102 , a compressor CPM- 100  to lift the feed supply pressure high enough to overcome the downstream flow resistance (pressure drop), a flow meter FM- 100  to measure and monitor the feed flow rate, and a check valve CV- 100  to prevent any possible backflow, before the feed stream reaching to the outlet connector QC- 104 . The supplementary fuel line will likely see a compressor CMP- 101 , a solenoid valve SOV- 103 , and a pressure regulator PR- 100 , before it is connected to the output connector QC- 105 . The supplementary fuel flow rate is adjusted by a control mechanism likely based on burner temperature and on the anode off gas flow rate that is supplied from the connector QC- 101  and mixed with the fuel prior to the QC- 105 . On the panel module  24 , there may also be installed one water pump P- 100  to deliver the water to the boiler, and two air blowers BL- 100  and BL- 101  to supply the air separately to burner, and preferential oxidizer (PROX) reactor, all inside the fuel processor module  21 . 
     It should be understood that all the components within the module  24  can be mounted on a two-dimensional panel or plate; therefore it can also be referred to as plate of balance of plant. This module can be manufactured separately, and the components can be installed and connected independently. The module will be eventually installed on a system frame structure, which will integrate all the system modules into the desired product. The module will be easily removable from such a frame structure, and be repaired or replaced. 
     Now referring to the fuel processor module  21  in  FIG. 6 , there are six input connectors QC- 109  to QC- 114  to be connected with the panel module  22  for various streams input, and three output connectors QC- 115  to QC- 117  for exiting the streams. The fuel processor shown schematically herein is a stream reforming based process developed by the author of the present invention. The fuel processor consists of several key components, including a hydrodesulfurizer (HDS), an integrated steam reformer and burner (SMR+Burner), three heat exchangers (HX- 1 , HX- 2 , and HX- 3 ), a desulfurized feed a superheated steam mixer, a steam boiler, a medium temperature water gas shift reactor (MTS), a low temperature water gas shift reactor (LTS), and a preferential oxidizer (PROX). All the components herein are preferably designed and constructed separately, and once manufactured they are linked or somehow stacked together according to the flow scheme to form an integrated compact device. This feature will allow ease of manufacturing, leak testing, and assembling. It also allows repairing or replacing individual components without destroying the entire fuel processor, once a failure has been detected in a component. 
     Now referring to  FIG. 7  for fuel cell module  31  and its balance of plant module  32 . Three connectors QC- 200 , QC- 201  and QC- 202  are placed on the panel module  32  to receive fuel stream  180 , nitrogen stream  310  and cogeneration water  370 . On each of the fuel and nitrogen line, there may be installed a solenoid valve (SOV- 200  and SOV- 201 ) and pressure regulator (PR- 200  and PR- 201 ). Before either fuel or nitrogen (only used when purging) is connected to the output connector QC- 203 , there is a hand valve HV- 200  for manual control. Two air blowers or compressors BL- 200  and BL- 201  are installed on the panel to supply air to the cathode of the fuel cell stack and a backup air cooling heat exchanger HX- 2 , respectively. The cogeneration water from the connector QC- 202  flows to the connector QC- 206 , while it might be partially or completely bypassed through a solenoid valve SOV- 202  to the output connector QC- 207 , which eventually is connected to the stream after the output connector QC- 213  on the fuel cell module  31 . 
     The fuel cell module shown schematically in  FIG. 7  is typical of the PEMFC system, which consists of several key components, including fuel cell stack having an anode, a cathode and a cooling side. There is an air humidifier, which humidifies the incoming cool and unsaturated air by exchanging humid and heat with the cathode exhausting air that is generally saturated at or near the stack temperature. There may also have another humidifier, in which the incoming dry hydrogen or semi-hydrated reformate can be humidified by exchanging humid and heat with the exhausting wet anode off gas. A heat exchanger HX- 1  is placed to remove the heat that the stack produced to the cogeneration water. A second heat exchanger HX- 2 , which differs from the HX- 1 , is also designed to serve as a backup heat exchanger, i.e. to remove the extra heat not sufficiently removed by the HX- 1 , to ensure an appropriate temperature of coolant before it flows into the coolant tank. A coolant circulation pump circulates the coolant back to the stack. All these components are preferably designed and constructed separately, and once manufactured they are linked or somehow stacked together according to the flow scheme to form an integrated compact device. 
     One may remove the PROX reactor, and probably LTS, from the fuel processor module shown in  FIG. 6 , when the produced reformate is supplied to a high temperature membrane fuel cell, in which the fuel cell stack can safely be operated with reformate containing up to a few percentage CO (e.g. 5%), therefore only a high and/or medium temperature water gas shift reactor can satisfy this CO level requirement. For high temperature fuel cells, it is also possible to remove one or two humidifiers shown in  FIG. 7  because humidification for high temperature membrane such as polybenzimidazoles (PBI) based is unnecessary. Instead, there may be an additional heat exchanger, arranged in a preferred way, to pre-heat the incoming cold air to close to the stack temperature, which is generally between 120 and 200° C. 
     Furthermore, there may be other variations to the fuel cell power system  10  of  FIG. 1 , by separating, combining or rearranging the basic subsystems, modules and components based on the present invention. One such example is schematically shown in  FIG. 8 , which is one of the preferred embodiments in accordance with the present invention for a combined heat and power plant based on a steam reforming based fuel processor and a high temperature membrane based fuel cell stack. In  FIG. 8 , the fuel processor module  21  can be similar to what is shown in  FIG. 6  but without LTS and PROX, and the fuel cell module  31  can be similar to what is shown in  FIG. 7  but without two humidifiers, and they can be manufactured separately as they are for low temperature fuel cell systems. Given the fact that the MTS temperature is in the same range as the high temperature fuel cell stack (i.e. 160-200° C.), the fuel processor module  21  and fuel cell module  31  can even be designed and manufactured as an integral assembly  60  as shown in  FIG. 8 , in which the MTS is expected to be placed in the neighborhood of the fuel cell stack. Accordingly, the balance of plant modules  22  and  32  for fuel processor subsystem  20  and for fuel cell subsystem  30  can be integrated to form an integrated balance of plant module  25  in  FIG. 8 , and all the electrical and control modules shown in  FIGS. 2 ,  3 ,  4  and  5  can be designed and manufactured as an integrated assembly  45 . In such an arrangement, a steam reforming and high temperature fuel cell based CHP system  10   a  will include five major modules, namely,
         an electrical and control module, in which all electrical and control devices are collectively installed, to control and operate the CHP system by interacting with other system modules;   a balance of plant module, in which all system balance of plant components such as valves, blowers, compressors, regulators, filters and pumps are collectively installed. It receives a fuel stream  100  and a water stream  300  from external supplying sources, and sends a feed stream  101 , a fuel stream  191 , an air stream  201  and a water stream  301  to the combined fuel processor and fuel cell module  60 . It may also receive electrical power and control signals from the electrical and control module  45  by preferably connecting with a cable  560 ;   a combined fuel processor and fuel cell module  60 , in which hydrocarbon feed is first converted to a hydrogen rich reformate in fuel processor part  21 , which is subsequently supplied to fuel cell  31  to react with air to generate electricity  400  and usable thermal energy, with the latter to be recovered by flowing a cogeneration stream  360  from, and  380  to, a heat recovery module  50 . The combined fuel processor and fuel cell module  60  may receive an electrical power and a control signal from, and send a control signal to, the aforementioned electrical and control module  45  through a connecting cable  561 ;   a power conditioning module  40 , which converts and conditions the fuel cell produced power  400  to generate an AC power  440  for end use. This module is essentially the same as one shown already in  FIG. 4 . The PCS module  50  is controlled by interacting with the electrical and control module  45  by connecting a cable  562 ; and   a heat recovery module  50 , which is essentially the same as one shown in  FIG. 5 .       

     The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.