JP4751589B2 - Fuel cell power generation system - Google Patents

Description

  The present invention generally relates to a fuel cell power generation system that generates power using a fuel containing hydrogen, and more particularly to a fuel cell power generation system having a heat supply function using heat generated by power generation.

  In recent years, as a fuel cell power generation system, practical use of a relatively small fuel cell power generation system for home use or small-scale business has been promoted. This system is generally used as a so-called cogeneration apparatus that supplies heat using electric power generated by power generation and exhaust heat generated by power generation.

  Conventionally, the fuel cell power generation system generally uses a hydrocarbon-based fuel such as city gas because of the limitation of the fuel supply base. Hereinafter, the configuration of the fuel cell power generation system will be briefly described.

  The system has a structure in which components including a fuel cell main body that generates direct current (DC) power are integrally stored in a package unit. Specifically, a reformer that generates hydrogen, a CO converter that converts carbon monoxide contained in a large amount of reformed gas into hydrogen, a CO selective oxidizer that oxidizes a slight amount of remaining carbon monoxide, and in the exhaust Contains a condenser that condenses the moisture of the battery, a battery cooling water system for controlling heat generated by power generation, a heat utilization system for supplying exhaust heat, and a heat exchanger that transfers heat from the battery cooling water system to the heat utilization system Has been.

  Moreover, since the demand for electricity and heat does not match, it is often the case that hot water is stored in a hot water tank provided outside the package unit and the hot water is supplied from the hot water tank to the user.

  In such a system, the reaction to convert hydrocarbon fuel such as city gas in the reformer into hydrogen is an endothermic reaction, so unreacted hydrogen contained in the exhaust from the fuel electrode of the fuel cell body is burned. Heat of reaction is given. These are designed to realize an optimally designed system so as to obtain high power generation efficiency and total efficiency including exhaust heat utilization.

  By the way, in the future, the development of a hydrogen supply infrastructure is planned, and it is thought that a hydrogen-circulating society will arrive. The fuel cell power generation system is expected to be an important component of a hydrogen recycling society. That is, a pure hydrogen type fuel cell cogeneration power generator supplies energy for home or small-scale business.

  In addition, as an effective system until a large-scale hydrogen supply base is established, a system that supplies hydrogen in units of apartment houses or local communities has been proposed (see, for example, Patent Document 1). Such a fuel cell cogeneration system installed in each home does not require a fuel processing device including a reformer, a CO converter, and a CO selective oxidizer, so that a simple configuration is possible.

  On the other hand, since the package unit of the fuel cell cogeneration installed in each home does not have a reformer, it has an afterburner for treating unreacted hydrogen contained in the exhaust from the fuel electrode of the fuel cell main body. A system is adopted in which heat is recovered from the combustion exhaust gas of the afterburner as hot water.

The combustion amount of the afterburner is determined by the fuel utilization rate of the fuel electrode of the fuel cell body. In such a fuel cell cogeneration system, it is proposed to control the ratio of heat output and power generation output by varying the fuel utilization rate. (For example, see Non-Patent Document 1). According to such a cogeneration system with variable thermoelectric ratio, it is possible to supply electric power and hot water most efficiently to homes having various energy consumption patterns.
Special Table 2002-544389 Design options for achieving a rapidly variable heat-to-power ratio in a combined heat and power (CHP) fuel cell system (FCS), W. Colella, Journal of Power Sources 4687 (2002) 1-8

  The thermoelectric ratio variable fuel cell cogeneration system using the afterburner as described above has the following technical problems to realize, and is difficult to realize. First, as a first problem, in a conventional system that uses pure hydrogen or a gas rich in hydrogen (hydrogen-rich gas) as a fuel, the fuel to the fuel cell main body is generally supplied at a flow rate installed upstream of the fuel cell main body. A fuel flow rate corresponding to the power generation output is supplied by a flow rate control function such as a regulating valve or a variable fuel pump. This fuel flow rate control function controls to flow a flow rate that combines the amount of hydrogen consumed in power generation in the fuel cell body and the amount of hydrogen corresponding to the amount of heat required for the afterburner.

  In such a fuel flow rate control system, the pressure downstream of the control function greatly fluctuates due to a change in the thermoelectric ratio, so that feedback control based on fuel flow rate measurement is required. When the power generation ratio is increased, hydrogen is consumed in the fuel cell, so the pressure decreases.However, when the heat output ratio is increased, the fuel flow rate through the fuel cell increases, and combustion in the afterburner As the load increases, the pressure on the downstream side of the control function increases.

  In general, when a fuel cell power generation system is operated in a state in which sufficient fuel is not supplied for power generation, the structural member is corroded and rapidly deteriorates. However, in such a system, when the heat load demand becomes low, the fuel utilization rate of the fuel cell body increases, so the difference between the fuel supplied by the fuel flow rate control function and the fuel flow rate consumed by the fuel cell body is different. As the fuel cell body becomes smaller, it is operated in a dangerous state.

  As a second problem, a variable thermoelectric ratio fuel cell cogeneration system using an afterburner can store hot water at a high temperature by recovering heat from the afterburner. Therefore, supply hot water in a relatively small hot water tank. Is possible. However, in this system, most of the exhaust heat obtained when the operation with a high power ratio is performed is usually low-temperature water of about 60 ° C., and thus it has not been an effective means.

  Further, as a third problem, the load change required for the afterburner in the system is very large, and it is difficult to cover with a normal combustor. For this reason, application of a catalytic combustor has been proposed (see Non-Patent Document 1 above).

  If a catalytic combustor is applied, a lean fuel containing hydrogen as a main component can be stably burned over a wide load range. However, since the surface of the catalyst used in the catalytic combustor is slightly oxidized at the time of stopping, it is necessary to reduce the oxidized surface at the time of startup. For example, when a combustion catalyst such as Pt or Pd is used, the reduction reaction rate is slow when the catalyst temperature is 70 ° C. or less, and there is a problem that the combustion reaction does not start for several minutes even when fuel is introduced.

  For this reason, in the catalytic combustor, the catalyst is preheated by an electric heater or the like. The catalyst layer has a structure such as a porous body, a packed bed of granular catalyst, a honeycomb, a wire mesh, etc. in order to allow the gas to flow with low pressure loss and to take a large contact area with the catalyst. However, there is a problem that it takes a long time to raise the temperature by the heating source. The temperature rise by the electric heater may be about 70 ° C., but when the catalytic combustion starts, the combustion temperature becomes a high temperature of about 400 ° C. to 600 ° C. For this reason, the electric heater is required to have high heat resistance, which is a high cost factor and a factor of reducing reliability.

  Therefore, the object of the present invention is to realize a fuel cell cogeneration system with a variable thermoelectric output ratio that uses a stable fuel control performance with a simple configuration, a highly reliable and highly efficient afterburner that can recover heat as high-temperature water. It is to provide a fuel cell power generation system that can be used.

A fuel cell power generation system according to an aspect of the present invention includes a fuel cell main body that generates power using a fuel containing hydrogen, and an exhaust gas containing a combustible component discharged from a fuel electrode included in the fuel cell main body. A combustor that burns with air discharged from an air electrode included in the fuel cell body; heat exchange means that recovers heat generated from the fuel cell body or the combustor as hot water; and fuel supply to the fuel electrode. And a flow rate adjusting means for adjusting a flow rate of the exhaust gas introduced from the fuel electrode into the combustor , wherein the flow rate adjusting means adjusts the pressure on the primary side by the flow rate of the exhaust gas. The pressure drop is set so that does not fluctuate .

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell cogeneration system of the thermoelectric output ratio variable type which uses together the afterburner which can recover heat | fever as high temperature water with high fuel efficiency, high reliability with high reliability by simple structure is realizable.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a main part of the fuel cell power generation system according to the first embodiment.

  The system includes a fuel cell package unit 1, a hydrogen gas source 2, and a hot water tank 4. For example, as shown in FIG. 3, the hydrogen gas source 2 is a hydrogen distribution system that supplies hydrogen in units of housing complexes or local communities.

  In this system, the centrally installed fuel processing apparatus 300 generates pure hydrogen or hydrogen rich gas (gas containing abundant hydrogen) from raw fuel and supplies it to the fuel cell package unit 1 installed in each household. . The hydrogen gas source 2 is a supply source or storage facility that distributes hydrogen gas through a pipeline. Hereinafter, pure hydrogen or hydrogen-rich gas is generically referred to as hydrogen gas.

  The fuel cell package unit 1 includes a fuel cell main body 10, a secondary pressure control valve 11, an exhaust flow rate adjustment valve 12, an air filter 13, an air blower 14, an exhaust heater 15, and an afterburner 20.

  The fuel cell body 10 includes a fuel electrode 10A to which hydrogen gas is supplied and an air electrode 10B to which air is supplied, and generates DC power. The hydrogen gas supplied to the fuel cell package unit 1 is always supplied to the fuel electrode 10A at a constant pressure by the secondary pressure control valve 11. In the fuel electrode 10A, a part of the hydrogen gas is consumed by the power generation reaction.

The exhaust flow rate adjustment valve 12 adjusts at the set flow rate, and supplies the fuel exhaust gas containing hydrogen gas from the fuel electrode 10 </ b> A to the afterburner 20. The exhaust flow rate adjusting valve 12 is set so that the pressure drop is sufficiently large so that the pressure on the primary side does not fluctuate due to the flow rate of the fuel exhaust gas from the fuel electrode 10A. That is, the exhaust of the fuel exhaust gas from the fuel electrode 10A is configured so that the opening in by that control of the exhaust flow rate adjusting valve 12, i.e., the flow rate have regulations that require feedback by measurement control becomes possible.

  Note that the secondary pressure control valve 11 is not required when the fuel supply pressure to the fuel cell package unit 1 is stably controlled on the supply equipment side that is the hydrogen gas source 2.

  The exhaust flow rate adjusting valve 12 has a fuel electrode 10A so that the flow rate determined by the power generation output of the fuel cell main body 10 or the flow rate determined by the load of the afterburner 20 required by the heat output command is larger. Is controlled (see FIG. 2).

  The afterburner 20 is a catalytic combustor having a combustion catalyst layer 20A inside so as to be able to cope with a wide combustion load range. A combustion catalyst temperature sensor 20B is installed in the vicinity of the combustion catalyst layer 20A.

  The air 3 from which impurities and dust are removed by the air filter 13 is supplied to the air electrode 10B of the fuel cell main body 10 by the air blower 14. This air flow rate can be adjusted by variable speed control of the air blower 14 or a flow rate adjusting valve. Further, the air flow rate is determined as a function of the opening command of the exhaust flow rate adjustment valve 12 of the fuel electrode 10A and the power generation amount of the fuel cell body 10. That is, an air flow rate proportional to the total fuel input amount to the fuel cell package unit 1 is supplied to the air electrode 10B. The exhaust heater 15 is provided in the air pipe downstream of the air electrode 10B and upstream of the fuel mixing unit 20C, and preheats the air exhausted from the air electrode 10B.

  Further, the fuel cell package unit 1 includes a battery cooling water circulation system 16, a battery cooling water heat exchanger 17, a bypass pipe 17A, a battery cooling water temperature sensor 18, a bypass flow rate adjustment valve 19, a combustion gas heat exchanger 21, and a condenser 22. And an exhaust heat recovery circulation system 23.

(Operational effects of the first embodiment)
Next, the operation of the system of this embodiment will be described.

  In the fuel cell main body 10, the fuel electrode 10 </ b> A consumes part of the supplied hydrogen gas by a power generation reaction, and exhausts fuel exhaust gas containing hydrogen gas. The exhaust flow rate adjustment valve 12 adjusts at the set flow rate, and supplies the fuel exhaust gas from the fuel electrode 10 </ b> A to the afterburner 20.

  On the other hand, the air exhausted from the air electrode 10B is preheated by the exhaust heater 15 and then mixed with the fuel exhaust gas in the mixing unit 20C and supplied to the afterburner 20. At the time of system start-up, the afterburner 20 starts with a purge before ignition with air, but when the catalyst layer temperature is a low state of 70 ° C. or lower, the air preheated by the exhaust heater 15 is mixed with the fuel exhaust gas. Supplied.

  After the burner 20 confirms that the temperature of the combustion catalyst 20A is 70 ° C. or higher by the combustion catalyst temperature sensor 20B, the afterburner 20 introduces the fuel exhaust gas (mixed with air). Such a method is not affected by the low thermal conductivity of the combustion catalyst 20A as compared with the conventional method of heating the combustion catalyst with a heater, so that the entire combustion catalyst 20A is uniform in a short time. It is possible to raise the temperature.

  Further, the exhaust heater 15 only needs to heat the air temperature from about 70 ° C. to about 150 ° C. Further, when in the operating state, only the exhaust gas from the air electrode 10B at about 60 ° C. to 80 ° C. passes. Therefore, according to the so-called preheating method for starting according to the present embodiment, it is not necessary to install a heater around the combustion catalyst 20A exposed to a high temperature. As the exhaust heater 15, a standard electric heater can be used, and relatively high durability can be maintained.

  By the afterburner 20, the combustion exhaust gas from the fuel electrode 10 </ b> A becomes a high-temperature combustion gas, and is discharged out of the fuel cell package unit 1 as the low-temperature exhaust gas 5 through the combustion gas heat exchanger 21 and the condenser 22. .

  Heat utilization of the fuel cell system of the present embodiment is performed by the exhaust heat recovery circulation system 23. Hereinafter, the heat supply system using the hot water of the hot water tank 4 will be described. In addition, the supply form of the heat to the user is not limited to the hot water storage tank 4, and the medium flowing through the exhaust heat recovery circulation system 23 is not limited to water.

  The hot water tank 4 stores hot water having a relatively low temperature in advance. Low-temperature water from the hot water tank 4 is supplied to the condenser 22 by the exhaust heat recovery circulation system 23 to recover condensation latent heat from the combustion gas containing a large amount of water vapor. At the same time, the condenser 22 collects water necessary for fuel cell power generation. Water from the condenser 22 is heated from about 60 ° C. to about 80 ° C. by the battery cooling water heat exchanger 17 and supplied to the hot water tank 4 as high-temperature water at 80 ° C. or more by the combustion gas heat exchanger 21.

  Further, the battery cooling water circulation system 16 has a battery cooling water heat exchanger 17, and the exhaust heat recovery circulation system 23 has a bypass pipe 17 </ b> A and a bypass flow rate adjustment valve 19. The flow rate of the exhaust heat recovery circulation system 23 is controlled so as to maintain the exhaust heat supply temperature at a set temperature.

  When the heat utilization load increases and a command to extract a large amount of heat output is issued, the amount of combustion of the afterburner 20 increases, and the amount of circulating water in the exhaust heat recovery circulation system 23 increases. The bypass flow rate adjustment valve 19 adjusts the flow rate of bypassing the battery cooling water heat exchanger 10 so as to maintain the battery cooling water temperature sensor 18 installed in the battery cooling water circulation system 16 in a predetermined temperature range. The battery cooling water temperature sensor 18 is normally installed at the outlet of the fuel cell main body 10, but is preferably installed at an optimum location for temperature control of the fuel cell main body 10 in the battery cooling water system 16.

  In the combined heat and power fuel cell system using the afterburner 20 of the present embodiment as described above, the secondary pressure control valve 11 can always supply fuel to the fuel electrode 10A of the fuel cell body 10 at a constant pressure. The risk of fuel shortage can be avoided in advance. In addition, since the fuel exhaust gas supplied to the afterburner 20 can be directly controlled by the exhaust flow rate adjusting valve 12, a heat supply system with good load followability of the afterburner 20 can be realized.

  In the conventional system, a fuel flow control valve that adjusts the hydrogen consumed by the afterburner in addition to the hydrogen consumed by the fuel cell main body is used. Therefore, a relatively large control valve is required. On the other hand, the exhaust flow rate adjustment valve 12 of the present embodiment adjusts only the supply of the fuel exhaust gas to the afterburner 20, so that a relatively small valve can be used. Accordingly, the overall size of the fuel cell package unit 1 can be reduced.

  Furthermore, if it is the system of this embodiment, a comparatively high temperature warm water can be preserve | saved in the hot water storage tank 4. FIG. Therefore, when realizing a combined heat and power system, the temperature of the fuel cell body 10 can be stabilized within a predetermined temperature range without being overcooled even if high temperature water can be taken out and the thermoelectric output ratio is variable. And can be maintained.

(Second Embodiment)
FIG. 4 is a diagram illustrating a configuration of a fuel cell system according to the second embodiment. In addition, about the same structure as 1st Embodiment, the same code | symbol as FIG. 1 is attached | subjected and description is abbreviate | omitted.

  In the fuel cell package unit 1 of the present embodiment, the fuel supply flow of the afterburner 20 that bypasses the fuel electrode 10A and the exhaust flow rate adjustment valve 12 downstream of the secondary pressure control valve 11 that adjusts the fuel supply pressure to the fuel electrode 10A. A passage 32 and a fuel flow rate adjusting valve 31 for controlling the fuel amount of the afterburner 20 are provided in the passage 32. The fuel flow rate adjustment valve 31 is controlled to increase the fuel of the after burner 20 when the required fuel amount of the after burner 20 cannot respond to the heat output increase command only by the amount controlled by the exhaust flow rate adjustment valve 12. The

  Further, downstream of the air blower 14 for supplying air to the air electrode 10B of the fuel cell main body 10, the air supply flow path 33 of the afterburner 20 that bypasses the air electrode 10B, and the air amount of the afterburner 20 in the flow path 33 An air flow rate adjusting valve 30 is controlled. The air flow rate adjusting valve 30 is controlled so as to supply an air amount proportional to the fuel amount of the after burner 20 supplied by the fuel flow rate adjusting valve 31 of the after burner 20.

  The first embodiment described above can realize a system that is effective when the thermoelectric output ratio is close to 1: 1 in the thermoelectric ratio variable system. On the other hand, according to the system of the present embodiment, the same effect as that of the first embodiment can be obtained even when the thermoelectric output ratio is double or triple.

(Third embodiment)
FIG. 5 is a diagram illustrating a configuration of a fuel cell system according to the third embodiment. In addition, about the same structure as 1st and 2nd embodiment, the same code | symbol as FIG.1 and FIG.4 is attached | subjected and description is abbreviate | omitted.

  The fuel cell package unit 1 of the present embodiment has a high-temperature water extraction heat exchanger 34 provided between the afterburner 20 and the combustion gas heat exchanger 21. This high-temperature water take-out heat exchanger 34 is connected to the absorption refrigerator 36 via a high-temperature water flow path 35 on the secondary side, and supplies high-temperature water. In addition, although this embodiment is a structure which uses the absorption refrigerator 36 as a utilization place of high temperature water, as a utilization place of high temperature water, it is not restricted to an absorption refrigerator.

  In such a system, as described above, the fuel input amount of the afterburner 20 is controlled by the exhaust flow rate adjusting valve 12. Here, when the high-temperature water take-out heat exchanger 34 takes out the high-temperature water and supplies it to the absorption chiller 36, the amount of fuel in the after burner 20 necessary for supplying the high-temperature water can be determined only by controlling the exhaust flow rate adjusting valve 12. It may not be secured. In such a case, the fuel flow control valve 31 of the afterburner 20 is controlled to increase the fuel of the afterburner 20.

  Further, the air flow rate of the afterburner 20 is controlled so as to supply an air amount proportional to the fuel amount supplied by the fuel flow rate adjusting valve 31 of the afterburner 20 as in the second embodiment.

  If it is the system of this embodiment, it will become possible to perform the utilization of the high-temperature water heat using the absorption chiller 36 etc. together with the low-temperature water heat utilization using the hot water tank 4 or the like.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram which shows the principal part of the fuel cell power generation system regarding the 1st Embodiment of this invention. The figure for demonstrating the exhaust flow control of the fuel electrode regarding the embodiment. The figure for demonstrating the hydrogen distribution system regarding the embodiment. The block diagram which shows the principal part of the fuel cell power generation system regarding 2nd Embodiment. The block diagram which shows the principal part of the fuel cell power generation system regarding 3rd Embodiment.

Explanation of symbols

1 ... Fuel cell package unit, 2 ... Hydrogen gas source, 4 ... Hot water tank,
DESCRIPTION OF SYMBOLS 10 ... Fuel cell main body, 10A ... Fuel electrode, 10B ... Air electrode, 11 ... Secondary pressure control valve,
12 ... Exhaust flow rate adjusting valve, 13 ... Air filter, 14 ... Air blower, 15 ... Exhaust heater,
16 ... Battery cooling water circulation system, 17 ... Battery cooling water heat exchanger, 18 ... Battery cooling water temperature sensor,
19 ... Bypass flow control valve, 20 ... Afterburner, 20A ... Combustion catalyst layer,
20B ... Combustion catalyst temperature sensor, 21 ... Combustion gas heat exchanger, 22 ... Condenser,
23 ... Waste heat recovery circulation system, 30 ... Air flow rate adjustment valve, 31 ... Fuel flow rate adjustment valve,
32 ... Fuel supply flow path, 33 ... Air supply flow path, 34 ... High temperature water extraction heat exchanger,
35 ... high-temperature water flow path, 36 ... absorption refrigerator.

Claims (13)

A fuel cell body that generates power using fuel containing hydrogen;
A combustor for combusting exhaust gas containing a combustible component discharged from a fuel electrode included in the fuel cell body with air discharged from an air electrode included in the fuel cell body;
Heat exchange means for recovering heat generated from the fuel cell body or the combustor as hot water;
A flow rate adjusting means for maintaining a constant pressure of fuel supply to the fuel electrode and adjusting a flow rate of the exhaust gas introduced from the fuel electrode to the combustor ;
The fuel cell power generation system according to claim 1, wherein the flow rate adjusting means is set so that a pressure on the primary side does not fluctuate depending on the flow rate of the exhaust gas . The flow rate adjusting means is
The exhaust gas flow rate is configured to be controlled at a flow rate which is larger of a flow rate required for the combustor according to a hot water supply amount by the heat exchange means or a minimum flow rate determined according to a power generation output of the fuel cell body. The fuel cell power generation system according to claim 1. Air supply control means for controlling an air supply amount when supplying air to the air electrode;
The air supply control means includes
3. The fuel cell power generation system according to claim 1, wherein the air supply amount is controlled as a function of a power generation output of the fuel cell main body and the exhaust gas flow rate. 4. The heat exchange means includes
A condensation heat exchanger for releasing latent heat of condensation of water vapor contained in the combustion gas, and first heat for generating hot water obtained by heating the hot water obtained by the condensation heat exchanger with the circulating water of the fuel cell body 4. The heat exchanger according to claim 1, further comprising: an exchanger; and a second heat exchanger that generates hot water obtained by heating hot water obtained by the first heat exchanger with heat of the combustion gas. The fuel cell power generation system according to any one of claims.   The fuel cell power generation system according to any one of claims 1 to 4, further comprising supply means for supplying hot water obtained by the heat exchange means to a hot water storage tank. The heat exchange means includes
Having bypass means for supplying hot water from the condensation heat exchanger to the second heat exchanger;
5. The fuel cell power generation system according to claim 4, wherein the bypass means controls the flow rate of the bypass so as to keep the temperature of the circulating water in the fuel cell main body constant. Temperature detecting means for detecting the hot water temperature of the second heat exchanger;
5. The fuel cell power generation according to claim 4, further comprising flow rate control means for performing flow rate control of the hot water so as to maintain the temperature of the hot water at a predetermined temperature according to a detection result of the temperature detection means. system.   The fuel cell power generation system according to any one of claims 1 to 7, wherein the combustor includes a combustion catalyst and catalyst temperature detection means for detecting the temperature of the upstream portion of the combustion catalyst. .   The heating means for heating the air discharged from the air electrode, and means for mixing the air heated by the heating means and the exhaust gas and supplying the mixed gas to the combustor. The fuel cell power generation system according to claim 8. First bypass means for supplying a part of the fuel to the combustor by bypassing the fuel electrode;
10. The fuel cell according to claim 1, further comprising second bypass means for supplying a part of the air to the combustor by bypassing the air electrode. 11. Power generation system. The first bypass means includes means for controlling a flow rate of the fuel to be bypassed according to a heat output of the combustor,
11. The fuel cell power generation system according to claim 10, wherein the second bypass means includes means for controlling the flow rate of the air in proportion to the flow rate of the fuel by the first bypass means.   The fuel cell power generation system according to any one of claims 1 to 11, further comprising a high-temperature water extraction heat exchanger provided on an output side of the combustor. The first bypass means includes means for controlling the flow rate of the fuel in response to the heat output of the combustor sufficient to remove hot water in a hot water removal heat exchanger;
The fuel cell power generation system according to claim 12, wherein the second bypass means includes means for controlling the flow rate of the air in proportion to the flow rate of the fuel by the first bypass means.

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