Patent Publication Number: US-2004043266-A1

Title: Solid polymer type fuel cell system

Description:
TECHNICAL FIELD  
       [0001] The present invention relates to a solid polymer type fuel cell system, which efficiently recovers condensed water from an exhaust gas and provides an efficient use of thermal energy as used when recovering the condensed water from the exhaust gas.  
       BACKGROUND OF THE INVENTION  
       [0002] With respect to an energy conversion apparatus having high efficiency, a fuel cell system has recently been notice widely. Some types of the fuel cell system have been operated or research and development thereof have been carried out. Of these systems, a solid polymer type fuel cell system, which utilizes a polymer membrane having a proton conductivity as electrolyte so as to provide a high power density with a compact structure and enable an operation with a simple system, has become a focus of attention in the field of stationary distributed power sources as well as the other power source used in space or vehicles. Such a power source has a structure as shown in FIGS. 9 and 10.  
       [0003] The solid polymer type fuel cell system includes three components into which the system is broadly divided, i.e., an electricity-generating system of a cell body, a fuel reforming system and a heat recovery system. The cell body of the electricity-generating system has a structure as described below.  
       [0004] The solid polymer type cell body is composed of a membrane electrode composite  4 , which is provided with a polymer membrane  1 , a sheet-shaped fuel electrode  2  serving as a gas diffusion electrode and an oxidant electrode  3 .  
       [0005] In the membrane electrode composite  4 , the polymer membrane  1  is held between the fuel electrode  2  serving as the diffusion electrode including catalyst of platinum and the oxidant electrode  3 .  
       [0006] The membrane electrode composite  4 , which includes the polymer membrane  1 , the fuel electrode  2  and the oxidant electrode  3 , is usually formed into a sheet having a square or rectangular shape.  
       [0007] The polymer membrane  1  is provided with a gasket  5  as shown in FIG. 11, which increases an area of the polymer membrane  1  larger than the fuel electrode  2  and the oxidant electrode  3  and enables it to come sufficiently into contact with reaction gases, which are to be supplied to the respective electrodes  2 ,  3 , thus preventing occurrence of mixture or disturbance of the reaction gases In addition, the polymer membrane  1  has a through-hole  6  serving as a manifold so as to cross the reaction gas at right angles.  
       [0008] There is a need to supply a fuel gas and an oxidant gas serving as the reaction gases to the respective electrodes  2 ,  3  in order to draw electricity out of the membrane electrode composite  4 . In this case, are forming gas having a principal component of hydrogen (i.e., fuel generated from hydrocarbon) is used as the fuel gas, and oxygen contained in air is used as the oxidant gas.  
       [0009] The following chemical reaction occurs so that hydrogen included in the fuel gas, which is supplied to the fuel electrode  2 , becomes proton and an electron:  
       H 2 →2H + +2 e   −   (1)  
       [0010] In the reaction expressed by the equation (1), the proton is transferred from the fuel electrode  2  to the oxidant electrode  3  in the polymer membrane  1  having a function of electrolyte. The electron is not capable of transferring in the polymer membrane  1 , but is transferred to the oxidant electrode  3  through an external electric circuit.  
       [0011] In the oxidant electrode  3 , the following chemical reaction occurs between the proton and the electron as transferred from the fuel electrode  2  and the oxygen serving as the oxidant to generate water:  
       2H + +1/2O 2 +2 e   − →2H 2 O   (2)  
       [0012] The thus generated water is generally called “generated water”. The generated water evaporates in the oxidant gas to become water vapor and to be discharged outside of the cell.  
       [0013] At this stage, electromotive forces (EMF difference) are generated in both the electrodes  2 ,  3 . A separator  7  is provided as shown in FIG. 11 so as to utilize the electromotive forces and prevent occurrence of mixture or disturbance of the reaction gases supplied to the respective electrodes  2 ,  3 . The separator  7  is integrally formed with the sides of the fuel electrode  2  and the oxidant electrode  3  to form a unit cell  8 .  
       [0014]FIG. 11 is a schematic drawing illustrating the unit cell  8 . The unit cell  8  is composed of the membrane electrode composite  4 , the fuel electrode  2 , the oxidant electrode  3 , the separator  7  and the gasket  5 . The separator  7  has reaction gas supplying holes (supplying manifolds)  9  for supplying the reaction gases to the respective unit sell  8 , reaction gas discharging holes (discharging manifolds)  10  for discharging the reaction gases from the respective unit sell  8 , and fuel gas passages  11  and oxidant gas passages  12  for connecting the reaction gas supplying holes  9  and the reaction gas discharging holes  10  to each other.  
       [0015] The electromotive force generated in the unit cell  8 , which includes the single membrane electrode composite  4 , is small of up to 1V. Accordingly, the unit cells  8  are placed one upon another in the form of laminate structure and subjected to an electric connection in series to provide a stack  13 , thus increasing the electromotive force. The stack  13  is fastened by means of a fastening mechanism such as a spring and a rod, after completion of the staking step of the unit sells  8 . In addition, the stack  13  is provided with a cooling plate (not shown) for cooling each of the unit cells  8 . Japanese Laid-Open Patent Application No. H01-140562 discloses measures to cool the stack  13  without using any cooling plate.  
       [0016] Now, the fuel reforming system will be described below.  
       [0017] The fuel gas supplied to the fuel electrode  2  mainly contains hydrogen. It is however difficult to supply the hydrogen with high purity. In view of these circumstances, the reforming gas is formed with the use of hydrocarbon fuel such as methane CH 4 , propane C 3 H 8 , methanol CH 3 OH and catalyst and the thus formed reforming gas is supplied to the cell body  15 . The system for forming the reforming gas is hereinafter referred to as the “fuel reforming system”  14 .  
       [0018] The fuel reforming system  14  adds water vapor to, for example, the methane CH 4  of the hydrocarbon fuel so as to reform the hydrogen in accordance with the following equation:  
       CH 4 +2H 2 O→4H 2 +CO 2    
       [0019] The above-mentioned equation is based on an endothermic reaction, thus loosing its balance with no application of heat. Accordingly, the fuel reforming system  14  returns the residual hydrogen H 2 , which has remained after supplying the hydrogen H 2  as reformed for example from the methane CH 4  to the cell body  15 , and then, adds air to the residual hydrogen to burn it.  
       [0020] With respect to the fuel reforming system  14 , there exists, as an oxygen adding system, a system of adding oxygen O 2  to, for example, the methane CH 4  of the hydrocarbon fuel to generate hydrogen H 2  and carbon monoxide CO in accordance with the following equation (3) and then supplying the hydrogen to the cell body  15 :  
       CH 4 +1/2O 2 →2H 2 +CO   (1)  
       [0021] Such a system however generates the carbon monoxide CO, thus causing unfavorable matters in operation. In vie of these aspects, there exists an improved fuel reforming system  14  in which a reforming reactor  16  is combined with a CO transformer  17  and a selective oxidizer  18 , water vapor H 2 O is added to, for example, the methane CH 4  Of the hydrocarbon fuel, the water vapor H 2 O is added to the generated carbon monoxide CO in the CO transformer  17  to generate hydrogen H2 and carbon dioxide CO 2  in accordance with the following equation (4) and oxygen O 2  contained in air is added to generate carbon dioxide CO 2  in accordance with the following equation (5):  
       CO transformer:CO+H 2 O→H 2 +CO 2    (4)  
       CO selective oxidizer:CO+1/2O 2 →CO 2    (5)  
       [0022] Now, the heat recovery system will be described below.  
       [0023] The heat recovery system includes a type of utilizing heat from refrigerant, which is supplied, for the purpose of cooling, to the cell body  15  and a type of recovering exhaust heat generated from the fuel reforming system  14 . The former heat recovery system  19  in which the refrigerant supplied for the purpose of cooling to the cell body  15  recovers heat and then is supplied as heat medium to the heat exchanger  20  as shown in FIG. 16, and then, makes a heat exchange with the other refrigerant to provide heat utilization for hot-water supply or heating, is disclosed for example in Japanese Laid-Open Patent Application No. H10-311564.  
       [0024] The latter heat recovery system  19  in which combustion exhaust gas is supplied from the fuel reforming system  14  to the heat exchanger  20  through the cell body  15 , the CO transformer  17  and the CO selective oxidizer  18  as shown in FIG. 17, and then heat-exchange with the refrigerant is made so as to provide heat utilization for hot-water supply or heating, or in which the refrigerant supplied to the heat exchanger  20  is converted into heat medium so as to provide heat utilization for hot-water supply, when supplying the combustion exhaust gas from the fuel reforming system  14  to the cell body  15  through the heat exchanger  20 , is disclosed for example in Japanese Laid-Open Patent Application No. H08-287932.  
       [0025] In addition, the heat recovering system  19  also includes recovery of water from the cell body  15  and the fuel reforming system  14 . Especially, the cell body  15  utilizes a large amount of pure water, with the result that there is need to make water in the cell body independent.  
       [0026] The concrete measures of making water independent include a type of making heat exchange between the combustion exhaust gas and the refrigerant in the heat recovering system  19  as shown for example in FIG. 19 so as to recover water contained in the combustion exhaust gas in the form of drain (i.e., condensed water), a type of making heat exchange between the combustion exhaust gas and ambient air in the heat recovering system  19  as shown for example in FIG. 20 so as to release heat into the ambient air by means of a fan  21  and recover water from the combustion exhaust gas in the form of drain (i.e., condensed water) and a type of making heat exchange between the combustion exhaust gas and refrigerant as circulated as shown for example in FIG. 21 so as to recover water from the combustion exhaust gas in the form of drain (i.e., condensed water).  
       [0027] The conventional solid polymer type fuel cell system utilizes the cell body, the fuel reforming system and the heat recovering system in a skillful combination to provide an energy conversion with high efficiency.  
       [0028] The conventional solid polymer type fuel cell system as shown in FIGS.  9  to  21  has some problems, especially, the problems of recovery of drain (i.e., condensed water) when making water independent.  
       [0029] The conventional solid polymer type fuel cell system makes heat exchange between the refrigerant or air and the combustion exhaust gas as described above, when recovering the water contained in the combustion exhaust gas in the form of drain, thus causing many problems on defects and inconvenience of fluctuations in amount of drain due to temperature of ambient air, failure in making the water independent at a high atmospheric temperature in the summer season, an excessively increased heat transfer face in case of a gas/gas heat exchange and a limited dew point of the combustion exhaust gas due to limitation in temperature effectiveness with the use of a fan.  
       [0030] An object of the present invention, which was made in view of the above-described circumstances, is to provide a solid polymer type fuel cell system, which provides effective and sufficient recovery of drain contained in a combustion exhaust gas and an effective utilization of the drain as recovered.  
       DISCLOSURE OF THE INVENTION  
       [0031] In order to achieve the aforementioned object, the solid polymer type fuel cell system, in which a fuel reforming system and a heat recovery system are combined with an electricity-generating system for chemically generating electricity, is characterized in that the heat recovery system comprises a water supply unit; a condensation heat exchange unit for converting water supplied from the water supply unit into hot water; and a hot water storage unit for temporarily storing the hot water from the condensation heat exchange unit and supplying same to a heat application unit.  
       [0032] In a preferred embodiment of the above-described aspect of the solid polymer type fuel cell system, the condensation heat exchange unit is divided into a first condensation heat exchange section and a second condensation heat exchange section, the first condensation heat exchange section being connected with a side of a fuel electrode of a cell body and the second condensation heat exchange section being connected with a side of at least an oxidant electrode of the cell body, in order to achieve the aforementioned object.  
       [0033] The condensation heat exchange unit may be divided into a gas-liquid separation section and a second condensation heat exchange section, the gas-liquid separation section being connected with a side of a fuel electrode of a cell body and the second condensation heat exchange section being connected with a side of at least an oxidant electrode of the cell body.  
       [0034] The first condensation heat exchange section and the second condensation heat exchange section may be provided at respective bottoms thereof with a common drain pool.  
       [0035] The gas-liquid separation section and the second condensation heat exchange section may be provided at respective bottoms thereof with a common drain pool.  
       [0036] The drain pool may be provided with an air supply unit.  
       [0037] The hot water storage unit may be a hot water tank.  
       [0038] The hot water storage unit may be provided with a sub-burning unit for heating the hot water, which is supplied from the condensation heat exchange unit, utilizing at least one of a part of fuel supplied to the fuel reforming system and unreacted fuel discharged from the electricity-generating system.  
       [0039] The hot water storage unit may be provided with a control valve for controlling a flow rate of the hot water supplied from the condensation heat exchange unit and with a valve-opening computing unit for processing a valve opening signal based on a temperature signal for the hot water and supplying same to the control valve.  
       [0040] The hot water storage unit may be a bathtub.  
       [0041] The bathtub may be provided with a heat exchange section received in a wall portion thereof, the heat exchange section being provided with a device for supplying the hot water from the condensation heat exchange unit and with a device for returning the hot water from the heat exchange section to an inlet of the condensation heat exchange unit.  
       [0042] Further, In order to achieve the aforementioned object, the solid polymer type fuel cell system, in which a fuel reforming system and a heat recovery system are combined with an electricity-generating system for chemically generating electricity, is characterized in that the heat recovery system comprises a water supply unit; a condensation heat exchange unit for converting water supplied from the water supply unit into hot water; a bathtub for utilizing the hot water from the condensation heat exchange unit as a hot bath; a heat exchange section for converting air into a hot-air with a use of the hot water from the condensation heat exchange unit as a heating source and supplying the hot-air to a heat application unit; and a device for returning the hot-water discharged from the heat exchange section to a water supply side of the condensation heat exchange unit.  
       [0043] Further, In order to achieve the aforementioned object, the solid polymer type fuel cell system, in which a fuel reforming system and a heat recovery system are combined with an electricity-generating system for chemically generating electricity, is characterized in that the heat recovery system comprises a water supply unit; a condensation heat exchange unit for converting water supplied from the water supply unit into hot water; and a hot water storage unit for temporarily storing the hot water from the condensation heat exchange unit and supplying same to a heat application unit, and the electricity-generating system is provided with a line for supplying part of condensed water, which is generated in the condensation heat exchange unit, to at least one of sides of a fuel electrode of a cell body and an oxidant electrode.  
       [0044] Further, in order to achieve the aforementioned object, the solid polymer type fuel cell system, in which a fuel reforming system and a heat recovery system are combined with an electricity-generating system for chemically generating electricity, is characterized in that the heat recovery system comprises a water supply unit; a condensation heat exchange unit for converting water supplied from the water supply unit into hot water; a device for supplying the hot water from the condensation heat exchange unit to a first heat application unit; a device for supplying the hot water to a second heat application unit, which is provided in parallel with the first heat application unit; a device for returning water, which has passed through the second heat application unit, to a water supply side of the condensation heat exchange unit; and an adjusting device for controlling an amount of heat supplied to the first or second heat application unit.  
       [0045] There may be comprised a hot water storage unit provided on an upstream hot-water side of the first heat application unit and a device for connecting a hot-water discharging side of the hot water storage unit with a hot-water supply side of the second heat application unit.  
       [0046] According to the present invention as described above, the solid polymer type fuel cell system comprises the fuel reforming system, the electricity-generating system and the heat recovery system so that electricity is generated in accordance with the chemical reaction, which is caused in the electricity-generating system, of reformed fuel generated in the fuel reforming system with air, there is made effective and sufficient recovery of drain that is included in the combustion exhaust gas as generated at this stage, to provide effective utilization of the drain as recovered, the exhaust gas is supplied to the heat recovery system to heat water from the water supply unit to provide hot water, utilizing the exhaust gas as a heating source, and supply the hot water to the heat application unit, on the one hand, and the drain as isolated from the exhaust gas is utilized in at least one of generation of the reformed fuel in the fuel reforming system and hot-water supply, on the other hand, thus making the water independent and providing effective utilization of heat. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0047]FIG. 1 is a schematic descriptive view illustrating a first embodiment of a solid polymer type fuel cell system according to the present invention;  
     [0048]FIG. 2 is a schematic descriptive view illustrating a second embodiment of the solid polymer type fuel cell system according to the present invention;  
     [0049]FIG. 3 is a schematic descriptive view illustrating a third embodiment of the solid polymer type fuel cell system according to the present invention;  
     [0050]FIG. 4 is a schematic descriptive view illustrating a fourth embodiment of the solid polymer type fuel cell system according to the present invention;  
     [0051]FIG. 5 is a schematic descriptive view illustrating a fifth embodiment of the solid polymer type fuel cell system according to the present invention;  
     [0052]FIG. 6 is a schematic descriptive view illustrating a sixth embodiment of the solid polymer type fuel cell system according to the present invention;  
     [0053]FIG. 7 is a schematic descriptive view illustrating a seventh embodiment of the solid polymer type fuel cell system according to the present invention;  
     [0054]FIG. 8 is a schematic descriptive view illustrating an eighth embodiment of the solid polymer type fuel cell system according to the present invention;  
     [0055]FIG. 9 is a schematic descriptive view illustrating a membrane electrode composite of a conventional solid polymer type fuel cell;  
     [0056]FIG. 10 is a plan view as viewed in a direction of an arrow “A” as shown in FIG. 8;  
     [0057]FIG. 11 is a schematic descriptive view illustrating a unit cell of the conventional solid polymer type fuel cell;  
     [0058]FIG. 12 is a schematic descriptive view illustrating a stack of the conventional solid polymer type fuel cell;  
     [0059]FIG. 13 is a schematic descriptive view illustrating a water vapor adding type fuel reforming system in the conventional solid polymer type fuel cell;  
     [0060]FIG. 14 is a schematic descriptive view illustrating an oxygen adding type fuel reforming system in the conventional solid polymer type fuel cell;  
     [0061]FIG. 15 is a schematic descriptive view illustrating the other fuel reforming system in the conventional solid polymer type fuel cell;  
     [0062]FIG. 16 is a schematic descriptive view illustrating the heat recovery system in the conventional solid polymer type fuel cell;  
     [0063]FIG. 17 is a schematic descriptive view illustrating the heat recovery system in the conventional water vapor adding type fuel reforming system;  
     [0064]FIG. 18 is a schematic descriptive view illustrating the heat recovery system in the conventional water vapor adding type fuel reforming system;  
     [0065]FIG. 19 is a schematic descriptive view illustrating the other heat recovery system in the conventional water vapor adding type fuel reforming system;  
     [0066]FIG. 20 is a schematic descriptive view illustrating the other heat recovery system in the conventional water vapor adding type fuel reforming system; and  
     [0067]FIG. 21 is a schematic descriptive view illustrating the other heat recovery system in the conventional water vapor adding type fuel reforming system. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
     [0068] Now, embodiments of a solid polymer type fuel cell system according to the present invention will be described hereunder in detail with reference to the accompanying drawings and reference numerals given thereon.  
     [0069]FIG. 1 is a schematic descriptive view illustrating the first embodiment of the solid polymer type fuel cell system according to the present invention.  
     [0070] The solid polymer type fuel cell system according to this embodiment has a structure in which an electricity-generating system  23  and a heat recovery system  24  are combined with a fuel reforming system  22 .  
     [0071] The fuel reforming system  22  comprises a reforming unit  29 , which includes a fuel reforming section  25 , a CO transformer  26 , a CO selective oxidizer  27  and a burning section  28 ; a gas-liquid separation unit  30  of pre-mixing, when supplying fuel, for example methane CH 4  from a fuel supply unit (not shown) to the reforming unit  29 , the fuel with water vapor H 2 O; and a blower  31  of supplying air to the CO selective oxidizer  27 .  
     [0072] The electricity-generating system  23  comprises a cell body  32 , which includes a stack (not shown) in which unit cells (not shown), each of which is composed of a fuel electrode, a polymer membrane and an oxidant electrode (all of them are not shown), are placed one upon another in the form of laminate structure; and a hot water heater  34 , which is provided on the side of the fuel electrode of the cell body  32  so as to circulate water in a circulation passage  45  provided with a heating section  33   a  and a pump  33   b,  heat the water in the heating section  33   a,  utilizing heat generated when generating electricity on the side of the fuel electrode and supply the hot water to a heat application unit such as a toilet seat.  
     [0073] The heat recovery system  24  comprises a water supply unit  66 , a condensation heat exchange unit  38  and a hot water storage unit  41 .  
     [0074] The water supply unit  66  is provided with a faucet  36  and a valve  37  so that water supplied from the outside, for example, service water is supplied to the condensation heat exchange unit  38 .  
     [0075] The condensation heat exchange unit  38  is divided into the first condensation heat exchange section  40   a  and the second condensation heat exchange section  40   b  so that the first condensation heat exchange section  40   a  is connected with the side of the fuel electrode of the cell body  32  through a fuel-exhaust gas pipe  35  and the second condensation heat exchange section  40   b  is connected with the side of the oxidant electrode of the cell body  32  through an oxidant-exhaust gas pipe  39 .  
     [0076] The first condensation heat exchange section  40   a  and the second condensation heat exchange section  40   b  are provided at the respective bottoms thereof with a common drain pool  53  and a blower  42  for supplying air to the drain pool  53 .  
     [0077] The hot water storage unit  41  temporarily stores the hot water, which is generated in the first condensation heat exchange section  40   a  and the second condensation heat exchange section  40   b  and supplies it to a heat application unit for the purpose of, for example, anus washing.  
     [0078] In the solid polymer type fuel cell system having such a structure, fuel, for example methane CH 4  supplied from the fuel supply unit is subjected to addition of water vapor H 2 O from the gas-liquid separation unit  30  and then supplied to the reforming unit  29  of the fuel reforming system  22 .  
     [0079] The water vapor reforming system is applied to the reforming-unit  29  so that air is supplied to the CO selective oxidizer  27  by means of the blower  31  when passing the mixture medium of methane CH 4  and water vapor H 2 O through the fuel reforming section  25 , the CO transformer  26  and the CO selective oxidizer  27  in this order, and a reforming gas mainly containing hydrogen H2 generates. The reforming gas generated in the reforming unit  29  has a CO concentration of about 50 ppm.  
     [0080] The reforming gas generated in the reforming unit  29  is supplied to the side of the fuel electrode of the cell body  32 , while air is supplied to the side of the oxidant electrode of the cell body  32  by means of the blower  42 . The blower  42  also supplies air to the burning section  28  of the reforming unit  29  as well as the drain pool  53  of the first condensation heat exchange section  40   a  and the second condensation heat exchange section  40   b  in the heat recovery system  24 . The air, which is to be supplied to the drain pool  53  of the first condensation heat exchange section  40   a  and the second condensation heat exchange section  40   b,  causes bubbling in the drain to remove CO 2  therein.  
     [0081] The cell body  23  causes the fuel electrode and the oxidant electrode to react with each other to generate water H 2 O and then the exhaust gas on the side of the fuel electrode is supplied to the first condensation heat exchange section  40   a  through the fuel-exhaust gas pipe  35 . At this stage, water, for example, service water supplied from the water supply unit  66  is heated to be hot water. The hot water is temporarily stored in the hot water storage unit  41  and then supplied to the heat application unit for the purpose of, for example, anus washing. The exhaust gas, which is supplied to the first condensation heat exchange section  40   a  heats water from the water supply unit and is then supplied as a fuel source to the burning section  28  of the reforming unit  29  through an exhaust gas pipe  46 .  
     [0082] The cell body  32  supplies the exhaust gas on the side of the oxidant electrode to the second condensation heat exchange section  40   b  through the oxidant-exhaust gas pipe  39 , together with the exhaust gas from the burning section  28 . At this stage, the water from the water supply unit  66  is also heated to be hot water. The hot water is temporarily stored in the hot water storage unit  41 , while part of the drain is returned to the gas-liquid separation unit  30  and the remaining part is discharged out of the system through a blowpipe  44 . The exhaust gas supplied to the second condensation heat exchange section  40   b  heats the water from the water supply unit  66  and is then released in the atmosphere as exhaust.  
     [0083] In addition, the cell body  32  heats water (i.e., cooling water) passing through the circulation passage  45 , in the heating section  33   a,  utilizing heat, which is generated during reaction between the fuel electrode and the oxidant electrode to generate water H 2 O so that the hot water is supplied to the hot water heater  34  by means of the pump  33   b  to heat water in the heat application unit such as the toilet seat.  
     [0084] According to the embodiment of the present invention, the water vapor, which is included in each of the exhaust gas generated from the fuel electrode of the cell body  32  and the exhaust gas generated from the oxidant electrode thereof, is recovered as a heat source for the first and second condensation heat exchange sections  40   a,    40   b,  in this manner, thus making the water independent and providing an effective utilization of heat.  
     [0085]FIG. 2 is a schematic descriptive view illustrating the second embodiment of the solid polymer type fuel cell system according to the present invention. The same reference numerals are added to the same structural components as those of the first embodiment.  
     [0086] In the solid polymer type fuel cell system according to the second embodiment, the condensation heat exchange unit  38  of the heat recovery system  24  is divided into the gas-liquid separation section  47  and the second condensation heat exchange section  40   b  so that the gas-liquid separation section  47  is connected with the side of the fuel electrode of the cell body  32  through the fuel-exhaust gas pipe  35  and the second condensation heat exchange section  40   b  is connected with the side of the oxidant electrode of the cell body  32  through the oxidant-exhaust gas pipe  39 .  
     [0087] In addition, in the solid polymer type fuel cell system according to the second embodiment, water, for example, service water from the valve  36  of the water supply unit  66  is subjected to the heat exchange in the second condensation heat exchange section  40   b  and a hot water storage bath  49 , which temporarily stores the hot water obtained through the heat exchange so as to supply the hot water to the heat application unit, is provided with a sub-burning unit  51  for burning the fuel, for example, methane CH 4 , which is supplied from the fuel supply system (not shown) through a fuel pipe  50 . The sub-burning unit  51  is operative under instructions from a temperature sensor  52  provided in the hot water storage bath  49 .  
     [0088] In the solid polymer type fuel cell system according to the second embodiment, the gas-liquid separation section  47  and the second condensation heat exchange section  40   b  are provided at the respective bottoms thereof with a common drain pool  53  so that drain from the drain pool  53  is supplied to the gas-liquid separation section  30  through a pump  43  and the remaining part of drain is supplied to the side of the fuel electrode of the cell body  32  through a drain supply pipe  55 , and further, heat generated on the sides of the polymer membrane, the fuel electrode and the oxidant electrode along with generation of electricity in the cell body  32  is removed, thus causing a so-called latent heat cooling, when moving the drain from the side of the fuel electrode to the side of the oxidant electrode. The remaining structural components are the same as those of the first embodiment and redundant description is therefore omitted.  
     [0089] According to the embodiment of the present invention, the water vapor, which is included in each of the exhaust gas generated from the burning section  28  of the reforming unit, the exhaust gas generated from the fuel electrode of the cell body  32  and the exhaust gas generated from the oxidant electrode thereof, is recovered by means of each of the gas-liquid separation section  47  and the second condensation heat exchange section  40   b  so that the recovered drain is supplied to each of the hot water storage bath  49  and the fuel electrode of the cell body  32 , thus making the water independent and providing an effective utilization of heat.  
     [0090]FIG. 3 is a schematic descriptive view illustrating the third embodiment of the solid polymer type fuel cell system according to the present invention. The same reference numerals are added to the same structural components as those of the first embodiment.  
     [0091] The solid polymer type fuel cell system according to the third embodiment is provided with the first drain supply pipe  57 , which performs the so-called latent heat cooling system in which the drain generated in each of the first condensation heat exchange section  40   a  and the second condensation heat exchange section  40   b  of the condensation heat exchange unit  38  is supplied to the side of the fuel electrode of the cell body  32  by means of the pump  56  so as to cool the sides of the fuel electrode and the oxidant electrode with the use of the drain water, on the one hand, and the second drain supply pipe  60  for supplying the above-mentioned drain to the CO transformer  26  of the reforming unit  29  in the form of water vapor H 2 O through the pump  58  and the gas-liquid separation unit  59 .  
     [0092] In addition, in the solid polymer type fuel cell system according to the third embodiment, there is provided a gas supply pipe  61  for supplying the gas generated in the first condensation heat exchange section  40   a  to the sub-burning unit  51  of the hot water storage bath  49 , a temperature sensor  52  detects the temperature of the hot water supplied from the second condensation heat exchange section  40   b  to the hot water storage bath  49  and there is provided a valve-opening computing unit  63  for controlling the valve opening of a temperature control valve  62 , when the detected signals exceed the predetermined temperature.  
     [0093] In the solid polymer type fuel cell system according to the third embodiment, the reforming unit  29  is provided with a heat exchange section  64  to cool the reforming unit  29 . There is provided a medium supply and discharge pipe  65  for supplying the medium as heated to the heat application unit (not shown). The remaining structural components are the same as those of the first embodiment and redundant description thereof is therefore omitted herein.  
     [0094] According to the third embodiment of the present invention, there is provided the first drain supply pipe  57  for causing the fuel electrode side of the cell body  32  to recover part of the drain, which is generated in the drain pool  53  of the first condensation heat exchange section  40   a  and the second condensation heat exchange section  40   b,  on the one hand, and the second drain supply pipe  60  for causing the CO transformer  26  of the reforming unit  29  to recover the remaining of the drain in the form of water vapor H2O, on the other hand, thus making the water independent.  
     [0095] In addition, in the third embodiment, there is provided the gas supply pipe  61  for supplying the gas generated from the first condensation heat exchange section  40   a  to the sub-burning unit  51  of the hot water storage bath  49 , the reforming unit  29  is provided with the heat exchange section  64  and there is provided the medium supply and discharge pipe  65  for supplying the obtained medium as heated to the heat application unit, thus providing an effective utilization of heat.  
     [0096]FIG. 4 is a schematic descriptive view illustrating the fourth embodiment of the solid polymer type fuel cell system according to the present invention. The same reference numerals are added to the same structural components as those of the first and second embodiments.  
     [0097] In the solid polymer type fuel cell system according to this fourth embodiment, the exhaust gas supplied from the side of the oxidant electrode of the cell body  32  through the oxidant-exhaust gas pipe  39  is utilized as the source of heat in the second condensation heat exchange section  40   b  of the condensation heat exchange unit  38  so as to heat water from the water supply unit  66  into hot water, and there are provided a bathtub  67  for storing the above-mentioned hot water to use same as bath, the sub-burning unit  51  for burning the fuel, for example, methane CH 4 , which is supplied from the fuel supply system (not shown) through the fuel pipe  50  and the temperature control valve  69  disposed on the inlet side of the bathtub  67  for controlling the valve opening under instructions of the temperature sensor  68  for detecting the temperature of the bath in the bathtub  67 . The remaining structural components are the same as those of the first and second embodiments and description thereof is therefore omitted herein.  
     [0098] According to the fourth embodiment, there are provided the bathtub  67  for utilizing, as the bath, the hot water generated in the second condensation heat exchange section  40   b  of the condensation heat exchange unit  38 , the sub-burning unit  51  for burning the fuel supplied from the fuel pipe  50  of the fuel supply system to reheat the hot water, and the temperature control valve  69  for controlling the bath temperature, thus providing an effective utilization of heat under a proper temperature control.  
     [0099]FIG. 5 is a schematic descriptive view illustrating the fifth embodiment of the solid polymer type fuel cell system according to the present invention. The same reference numerals are added to the same structural components as those of the first and second embodiments.  
     [0100] In the solid polymer type fuel cell system according to this fifth embodiment, water, for example, service water, which is supplied through a faucet  36 , valves  70 ,  71  of the water supply unit  66  to each of the first condensation heat exchange section  40   a  that is connected from the side of the fuel electrode of the cell body  32  through the fuel-exhaust pipe  35  and the second condensation heat exchange section  40   b  that is connected from the side of the oxidant electrode of the cell body  32  through the oxidant-exhaust gas pipe  39 , is heated to be hot water, and there are provided a bathtub  67  for storing part of the above-mentioned hot water to use same as bath, a heat exchange section  73  embedded in a wall portion  72  of the bathtub  67  for utilizing the remaining hot water as the heating source for the bath, and a hot water returning pipe  74  for returning the hot water discharged from the heat exchange section  73  to the outlet side of the faucet  36  of the water supply unit  66  by means of a pump  78 .  
     [0101] In addition, the solid polymer type fuel cell system according to the fifth embodiment is provided with a bath pipe  79  for supplying the hot water, which is generated in the first condensation heat exchange section  38  and the second condensation heat exchange section  40  of the condensation heat exchange unit  38 , to the bathtub  67  in the form of bath, and with a temperature control valve  69  for controlling the valve opening under instructions of the temperature sensor  68 , which is provided in the bath pipe  79 . The remaining structural components are the same as those of the first and second embodiments and description thereof is therefore omitted herein.  
     [0102] According to the fifth embodiment, the water from the water supply unit  66  is heated to be the hot water by means of the first condensation heat exchange section  40   a  and the second condensation heat exchange section  40   b,  part of the hot water is subjected to control with the use of the temperature control valve  69  and the remaining hot water is supplied to the heat exchange section  73  provided in the wall portion  72  for the purpose of heating the bath, when supplying the hot water to the bathtub  67  in the form of bath, and there is provided a hot water returning pipe  74  for returning the hot water as reheated to the water supply unit  66 , thus providing an effective utilization of heat under a proper temperature control.  
     [0103] In the fifth embodiment, the water from the water supply unit  66  is heated to be the hot water by means of the first condensation heat exchange section  40   a  and the second condensation heat exchange section  40   b  and the above-mentioned hot water is supplied to the bathtub  67  in the form of bath so as to utilize part of the hot water as the reheating source. However, the present invention is not limited only to such an embodiment, and there may be adopted, for example, measures as shown in FIG. 6 of supplying the hot water from the second condensation heat exchange section  40   b  of the condensation heat exchange unit  38  to the bathtub  67 , while supplying part of the hot water to a heat exchange section  76  provided in the outside of the bathtub, under the control of the temperature sensor  75 , raising the temperature of air sucked by means of the fan  77  and supplying hot air having the raised temperature to the heat application unit such as a drying room or a bath room. The hot water, which has been subjected to the temperature-raising process of the air supplied from the fan  77 , is returned to the water supply unit  66  through the hot water returning pipe  74 .  
     [0104]FIG. 7 is a schematic descriptive view illustrating the seventh embodiment of the solid polymer type fuel cell system according to the present invention. The same reference numerals are added to the same structural components as those of the first and sixth embodiments.  
     [0105] In the solid polymer type fuel cell system according to this seventh embodiment, water from the water supply unit  66  is heated to be hot water in the second condensation heat exchange section  40   b  of the condensation heat exchange unit  38 , utilizing, as the heating source, the exhaust gas supplied from the side of the oxidant electrode of the cell body  32  through the oxidant-exhaust gas pipe  39 , the hot water is supplied to the hot water storage unit  41  through pipes  79 ,  84 ,  85  and then supplied to the first heat application unit for the purpose of hot water supply or taking a shower, as an occasion demands.  
     [0106] In addition, there is adopted a structure in which a heat exchange section  76  serving as the second heat application unit for the purpose of floor heating is provided in parallel with the hot water storage unit  41  so that the heat is retuned to the water supply side of the condensation heat exchange unit  38  by means of a pipe  88  and a pump  78 , after supplying the heat to the floor. Application of the heat exchange section  76  is not limited only to the floor heating, but it may be applied to a heating device or a hot air supplying device which is built in a wall.  
     [0107] In addition, an air-cooled heat exchange section  81  is provided, through a valve  83 , a pump  78 , and a pipe  87 , as a temperature (thermal energy) control device for the hot water, which has passed through the condensation heat exchange unit  38 , so that the above-mentioned hot water is introduced into the air-cooled heat exchange section  81  by the operation of the pump  78  and cooled with air supplied by the fan  82  and then retuned to the water supply side of the condensation heat exchange unit  38 .  
     [0108] The heat exchange section  81  and the fan  82  are used in case where the heat utilization is not conducted in the first and second heat application units or the thermal energy as utilized is to be decreased. With respect to the control device thereof, the temperature sensor  75  detects the temperature of the hot water, which is to be supplied to the hot water storage unit  41  and the heat exchange section  76  for the floor heating, and the detected signals are fed back relative to the opening of the valves  80  and  83 , and the number of rotations of the pump  78 , thus making a control. The opening control of the valve  36  for the water supply unit may also be made.  
     [0109] According to the seventh embodiment, the water from the water supply unit  66  is heated to be the hot water in the second condensation heat exchange section  40   b,  and there is provided the temperature control unit such as the air-cooled heat exchange section  81  and the temperature sensor  75  for controlling the temperature or flow rate of the hot water, when supplying the hot water to the first heat application unit through the hot water storage unit  41  or to the second heat application unit provided in parallel with it, thus providing an effective utilization of heat under a proper temperature control.  
     [0110] Providing the pipe  92  and the valve  93  as the device for connecting the hot water storage unit  41  to the pipe  86 , which is disposed on the upstream side of the heat exchange section  76  for the floor heating, makes it possible to supply the hot water as stored in the hot water storage unit  41  by the operation of the pump  78  in case where the solid polymer type fuel cell system has not as yet been initiated or during a period of time from the initiating of the system to the generation of electricity. In addition, circulation of the water in the hot water storage unit  41  leads to prevention of occurrence of corrosion. In this case, the pipe  92  may not be directly connected to the hot water storage unit  41 , but be connected to the pipe  89 .  
     [0111] Industrial Applicability  
     [0112] As described above in detail, the solid polymer type fuel cell system according to the present invention comprises the fuel reforming system, the electricity-generating system and the heat recovery system so that electricity is generated in accordance with the chemical reaction, which is caused in the electricity-generating system, of reformed fuel generated in the fuel reforming system with air, and the thus generated exhaust gas is supplied to the heat recovery unit and the water from the water supply unit is heated to be hot water, utilizing the exhaust gas as the heating source so that the hot water is supplied to the heat application unit, while utilizing the drain as isolated from the exhaust gas in at least one of generation of the reformed fuel in the fuel reforming system and hot-water supply, on the other hand, thus making the water independent and providing effective utilization of heat.