JPS63254675A - Fuel cell power generating system - Google Patents

Abstract

PURPOSE:To mitigate the fluctuation of the system pressure and improve the reliability of a cell by maintaining the flow of the raw fuel constant against the flow change of the fuel gas fed to the fuel cell by the temperature control of a reforming reaction catalyst layer. CONSTITUTION:The flow of the raw fuel 1 is controlled to the fixed value given in response to the load current of a fuel cell 12. Only the reformed gas excessive for the target fuel reforming pressure is released through a bypass flow control valve 11 provided on a bypass line 10, the pressure of a fuel reforming system is thereby controlled. In this case, the fuel flow for a burner 9 is controlled in response to the combustion heat of the reformed gas flow flowing into an auxiliary burner 9, the fluctuation of the system pressure due to the fluctuation of the combustion quantity by the burner 9 is thereby mitigated. When an absorber tank is provided between the valve 11 and the burner 9, the pressure control can be supplemented. The fluctuation of the system pressure is thereby mitigated, and the reliability is improved.

Description

Detailed Description of the Invention [Objective of the Invention (Industrial Application Field) The present invention relates to a fuel cell power generation system comprising a fuel cell, a fuel reformer, and an air supply device, and particularly relates to a fuel cell power generation system comprising a fuel cell, a fuel reformer, and an air supply device. The present invention relates to a fuel cell power generation system in which the flow rate of raw fuel can be kept constant despite changes in the flow rate of fuel gas supplied to the fuel electrode of a fuel cell due to temperature control of a reforming reaction catalyst layer of a reforming device.

(Prior Art) Fuel cells are conventionally known as devices that directly convert chemical energy contained in fuel into electrical energy. This fuel cell usually has a pair of electrodes, a fuel electrode and an oxidizer electrode, with an electrolyte layer in between, and a fuel gas such as hydrogen gas is supplied to the fuel electrode, and an oxidant gas such as air is supplied to the oxidizer electrode. The system uses the electrochemical reaction that occurs at this time to extract electrical energy from between the two electrodes, and as long as the fuel gas and oxidant gas are supplied, electrical energy can be extracted with high conversion efficiency. It is something that can be taken out.

Currently, fuel cells that are being considered include fuel cells that use hydrazine as fuel, alkaline aqueous electrolytes, and phosphoric acid aqueous electrolytes as electrolytes. Among these, fuel cells that use phosphoric acid aqueous electrolytes as electrolytes Since it can use reformed gas, it can be used in general, and it is being used for industrial purposes and power generation projects. This type of fuel cell is equipped with a fuel reformer to obtain reformed gas containing a large amount of hydrogen gas, which is the fuel gas, and an air supply device to obtain compressed air, which is the oxidant gas. It often constitutes a fuel cell power generation system.In addition, in this type of fuel cell power generation system,
(a) Pressure control of the fuel reforming system, (b) Temperature control of the reforming reaction catalyst layer of the fuel reformer, (C) Exhaust gas discharged from the oxidizer electrode of the fuel cell and exhaust gas discharged from the fuel reformer. The three main control factors are pressure control at the confluence point with high-temperature exhaust gas (hereinafter referred to as system pressure).

The fourth factor shows an example of this type of conventional fuel cell power generation system. In FIG. 4, a raw fuel 1 made of fossil fuel such as natural gas or coal gas and steam from a steam supply device 2 are supplied to a raw fuel flow control valve 3, respectively.
The steam and carbon are controlled by the steam flow rate control valve 4 so that the mixing molar ratio of steam and carbon is about 3 to 5, and then introduced into the reforming reaction tube 6 in the fuel reformer 5. Here, the raw fuel 1 and steam are heated to about 500 to 800°C to perform a reforming reaction, and then the high temperature shift converter 7 and the low temperature shift converter 8
After that, it becomes a reformed gas with a high hydrogen content, that is, a fuel gas. This fuel gas with a high hydrogen content is sent to the auxiliary burner 9 through a bypass line 10. Bypass flow control valve 11
is also sent to the fuel electrode 12A of the fuel cell 12 via the fuel gas supply line 13 and the fuel flow control valve 14, respectively.

Hydrogen in the fuel gas that has flowed into the fuel electrode 12A of the fuel cell 12 undergoes a catalytic reaction with oxygen in the oxidant gas that has flowed into the oxidizer electrode 12B of the fuel cell 12, and as a result, a portion of the fuel gas is Electrical energy and reaction water are obtained by being consumed. The fuel exhaust gas exiting the fuel electrode 12A containing a part of the reaction water generated in the fuel cell 12 is passed through the fuel gas discharge line 15 as a combustion fuel for the burner 16 of the fuel reformer 5. Sent. And burner 1
The fuel exhaust gas sent to 6 is burned in the fuel reformer 5,
After heating the reforming reaction tube 6, it is discharged as high-temperature exhaust gas 17. Furthermore, this high-temperature exhaust gas 17 is introduced into a mixer 19 after being combined with the oxidant exhaust gas sent from the oxidizer electrode 12B of the fuel cell 12 via the oxidizer gas discharge line 18, and is introduced into the mixer 19, which is supplied with air from the turbine 2OA and the compressor 20B. It is used as part of the energy for driving the device 20. On the other hand, the auxiliary burner fuel supply line 21. The fuel for the auxiliary burner is sent through the auxiliary burner fuel flow control valve 22 and burns in the auxiliary burner 9 together with the above-mentioned fuel gas sent to the auxiliary burner 9, and the combustion gas passes through the mixer 19. Then, the turbine 20A of the air supply device 20 is driven.

On the other hand, the air discharged from the compressor 2OB connected to and driven by the turbine 2OA is supplied to the auxiliary burner 9 and the burner 16.
The air/fuel is adjusted and sent to the fuel cell 12 via the oxidant gas supply line 25 and the oxidant gas flow rate control valve 26 by the oxidant gas flow rate control valve 23.1 and other gas flow temperature control valve 24, respectively. The surplus is sent to the oxidizer electrode 12B of the air supply bag through the system differential pressure control valve 27! 20 is sent to the mixer 19 as part of the driving energy.

A part of the oxidant gas that has flowed into the oxidizer electrode 12B of the fuel cell 12 is consumed by reacting with hydrogen in the fuel gas that has flowed into the fuel electrode 12A of the fuel cell 12.
It is discharged containing the water produced in B. This discharged oxidizer exhaust gas is a high-temperature exhaust gas 1 from the fuel reformer 5.
It will join up with 7. Note that 28 is an inverter that converts the DC output obtained from the fuel cell 12 into AC.

Now, in such a fuel cell power generation system, the pressure control of the fuel reforming system is based on the deviation between the pressure value detected by the pressure detector 29 of the reformed gas on the outlet side of the low temperature shift converter 8 and the pressure setting value. By controlling the opening degree of the raw fuel flow rate control valve 3 provided on the supply line of the raw fuel 1 by the pressure control device 30, the pressure of the reformed gas on the outlet side of the low temperature reformer 8 is kept constant. It will be held in Further, temperature control of the reforming reaction catalyst layer of the fuel reformer 5 is performed based on the detected humidity value of the reforming reaction catalyst layer A layer of the fuel reformer 5 by the temperature detector 31 and the load current value of the fuel cell 12. The temperature control device 32 compares the corresponding temperature setting value, and the flow rate control device 34 compares the comparison value with the detected value of the flow rate of the fuel gas flowing through the fuel gas supply line 13 by the flow rate detector 33. By controlling the opening degree of the fuel flow control valve 14 provided on the fuel gas supply line 13, the fuel reformer 5
The temperature of the reforming reaction catalyst 1711H is kept constant. Furthermore, the system pressure can be controlled by pressure sensor 3.
Based on the deviation between the system pressure detection value and the pressure setting value by 5, the system pressure control device 36 controls the fuel flow control valve 2 provided on the supply line of the auxiliary burner fuel 21.
By controlling the opening degree of 2, the system pressure is maintained at the system specification pressure.

By the way, in the above description, regarding the temperature control of the reforming reaction catalyst layer of the fuel reformer 5, the fuel electrode 1 of the fuel cell 12
The pressure fluctuation in the fuel reforming system by controlling the flow rate of the fuel gas supplied to the fuel electrode 2A is controlled by the flow rate control of the raw fuel.
Although it will change depending on the flow rate of fuel gas supplied to the fuel reformer [5, the reforming reaction is an endothermic reaction,
Further, this reaction heat is transferred to the reforming reaction catalyst layer faster than the combustion heat of the fuel reformer M5. For this reason, the fuel cell 12
For controlling the flow rate of fuel gas supplied to the fuel electrode 12A,
The temperature of the reforming reaction catalyst layer responds in a reverse manner as shown in FIG. 5, and this makes temperature control of the reforming reaction catalyst layer extremely difficult. In other words, the flow rate of the raw fuel changes with the control of the flow rate of fuel gas supplied to the fuel electrode 12A of the fuel cell 12, and the amount of reformed material changes, which is a serious impediment to the above-mentioned temperature control. .

(Problems to be Solved by the Invention) As described above, in the conventional fuel cell power generation system, the pressure of the fuel reforming system is controlled by controlling the raw fuel flow rate, so the reforming reaction catalyst layer When the flow rate of fuel gas supplied to the fuel cell changes due to temperature control, the amount of raw fuel also changes, and this change in the amount of heat absorbed makes temperature control difficult.

The present invention was made to solve the above-mentioned problems, and its purpose is to keep the flow rate of raw fuel constant despite changes in the flow of fuel gas supplied to the fuel cell by controlling the temperature of the reforming reaction catalyst layer. A highly reliable fuel N pond that can easily control the temperature of the reforming reaction catalyst layer and minimize fluctuations in system pressure caused by the pressure control of the fuel reforming system. Our goal is to provide power generation systems.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention includes a fuel reformer, an air supply device, a fuel cell, an auxiliary burner, and a mixer. In the above-mentioned fuel cell power generation system, which is configured with A flow control means for controlling the opening degree of the raw fuel flow rate control valve provided on the raw fuel supply line, and a comparison between the detected pressure value of the reformed gas on the outlet side of the fuel reformer and the pressure set value. Based on the results, the fuel reforming system pressure control means consisting of pressure control means for controlling the opening degree of the bypass flow rate υ110 valve provided on the bypass line, and the detected temperature value of the reforming reaction catalyst layer of the fuel reformer. Based on the comparison result between the temperature set value and the detected flow rate of the fuel gas flowing through the fuel gas supply line to the fuel electrode of the fuel cell, the first temperature control means for the reforming reaction catalyst layer that controls the opening degree of the fuel flow control valve, and the pressure at the confluence point of the exhaust gas discharged from the oxidizer electrode of the fuel cell and the high-temperature exhaust gas discharged from the fuel reformer. A system pressure control means that controls the opening degree of a second fuel flow control valve provided on the auxiliary burner fuel supply line based on the comparison result between the detected value and the pressure set value, or the oxidizer of the fuel cell. Auxiliary burner fuel obtained based on the detected pressure at the confluence of the exhaust gas discharged from the pole and the high-temperature exhaust gas discharged from the fuel reformer, the pressure setting value, and the detected flow rate of the reformed gas flowing through the bypass line. Based on the comparison result between the flow rate command value and the detected flow rate value of the auxiliary burner fuel flowing through the auxiliary burner fuel supply line, the second
system pressure control means for controlling the opening degree of the fuel flow control valve, or bypass flow on the bypass line] II i
An absorber tank for absorbing pressure fluctuations is provided between the ll valve and the auxiliary burner.

(Function) In the above-described fuel cell power generation system, the flow rate of raw fuel is controlled to a constant value given according to the load current of the fuel cell, and the amount of reforming after reforming that is excessive to achieve the target fuel reforming pressure is controlled. The pressure of the fuel reforming system is controlled by letting only the quality gas escape through a bypass flow control valve provided on the bypass line. In addition, in this case, by controlling the pressure of the fuel reforming system, the flow rate of fuel for the auxiliary burner supplied to the auxiliary burner is controlled by considering the amount of reformed gas flowing into the auxiliary burner that is commensurate with the combustion heat. By doing so, fluctuations in the system pressure due to fluctuations in the amount of combustion in the auxiliary burner accompanying the pressure control of the fuel reforming system can be suppressed. Alternatively, by providing an absorber tank for absorbing pressure fluctuations between the bypass flow control valve and the auxiliary burner on the bypass line, it is possible to prevent fluctuations in the combustion amount in the auxiliary burner due to pressure control of the fuel reforming system. Fluctuations in system pressure are similarly mitigated.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows in block form an example of the configuration of a fuel cell power generation system according to the present invention. The same parts as in FIG. I will only talk about.

That is, FIG. 1 shows a raw fuel flow rate calculation device 38A that obtains a flow rate command value of the raw fuel 1 according to a detection signal 37 of the load current of the fuel cell 12, and a raw fuel flow rate calculation device 38A that calculates the flow rate command value of the raw fuel 1 flowing through the raw fuel 1 supply line. The flow rate detector 39 detects the flow rate and the detected flow rate value of the raw fuel 1 flowing through the raw fuel 1 supply line by the flow rate detector 39.

The opening degree of the raw fuel flow rate control valve 3 provided on the raw fuel supply line is controlled based on the deviation that is the result of comparison with the raw fuel flow rate command value from the raw fuel flow rate calculation device 38A. Flow rate control means consisting of a flow rate calculation device 38B,
and the pressure detector 29 that detects the pressure of the reformed gas on the outlet side of the low temperature shift converter 8, and the deviation that is the comparison result between the pressure detection value from this pressure detector 29 and the pressure setting value. Reforming system pressure control device 40 that controls the opening degree of the bypass flow control valve 11 provided on the bypass line 10
A pressure control system for a fuel reforming system is constructed by a pressure control means consisting of the following. Here, raw fuel 1
The flow rate command value is set in advance to a value slightly larger than the steady value of the raw fuel flow rate required to obtain a predetermined reforming pressure at each load.

Next, the operation of the fuel cell power generation system configured as described above will be described.

In FIG. 1, the raw fuel 1 for reforming and steam are introduced into the fuel reformer 5, and the flow rate of the raw fuel 1 at this time is determined by the load current detection signal of the fuel cell 12 from the raw fuel flow rate calculation device 38A. Given according to 37.

The flow rate command value of the raw fuel 1 is set in advance to a value slightly larger than the steady value of the raw fuel flow rate required to obtain a predetermined reforming pressure at each load, and the raw fuel 1 is determined by the flow rate detector 39.
The raw fuel flow rate υ1m is controlled by the raw fuel flow rate υ1m device 38B based on the deviation from the detected flow rate value of the raw fuel 1 flowing through the supply line. The thus controlled mixed gas of the raw fuel 1 and steam is reformed into a reformed gas through the reforming reaction tube 6 of the fuel reformer 5, and further reformed into a reformed gas through the high temperature shift converter 7. The gas is transformed through the low-temperature transformer 8 and becomes a hydrogen-rich reformed gas.

On the other hand, the pressure of the reformed gas on the outlet side of the low-temperature shift converter 8 is detected by a pressure detector 29, and the reforming system pressure is controlled based on the deviation between the pressure detection value from the pressure detector 29 and the pressure setting value. By controlling the opening degree of the bypass flow control valve 11 provided on the bypass line 10 using the bag [40], the pressure of the fuel reforming system is controlled. That is, if the flow rate of fuel gas supplied to the fuel electrode 12A of the fuel cell 12 increases and the pressure of the fuel reforming system decreases, the bypass flow rate to the auxiliary burner 9 through the bypass line 10 is reduced, and vice versa. When the flow rate of fuel gas supplied to the fuel electrode 12A of the fuel cell 12 decreases and the pressure of the fuel reforming system increases, the auxiliary burner 9 through the bypass line 10
Increase bypass flow to.

In this way, while controlling the flow rate of the raw fuel 1 to a constant value given according to the load current of the fuel cell 12, only the reformed gas after reforming that is excessive to achieve the target fuel reforming pressure is
Bypass flow rate υ11 provided on the bypass line 10
[The pressure of the fuel reforming system is controlled by releasing the fuel through the l valve 11. Note that the reason why the raw fuel flow rate is set to be slightly larger than the required steady-state value in the above is because it is possible to cope with a decrease in the fuel reforming system pressure.

As described above, in this embodiment, in order to control the temperature of the reforming reaction catalyst layer of the fuel reformer 5, even if the flow rate of the fuel gas supplied to the fuel electrode 12A of the fuel cell 12 changes, the fuel reforming is performed. The reformed amount of the reformed gas in the device 5 is always kept constant under the same load current, and as a result, there is no immediate reverse response decrease depending on temperature, so that the reforming reaction catalyst in the fuel reformer 25 It becomes possible to further improve the controllability (responsiveness, stability) of the layer. Therefore, if the responsiveness of the reforming reaction catalyst layer of the fuel reforming bag [5 is improved, the responsiveness of the system will be improved, the load responsiveness will be improved, and strict specifications can be satisfactorily met.

Next, other embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows in block form another example of the configuration of the fuel cell power generation system according to the present invention, and the same parts as in FIG. Only the different parts will be described.

That is, FIG. 2 shows the detection of the system pressure at the confluence point of the exhaust gas discharged from the oxidizer electrode 12B of the fuel cell 12 and the high-temperature exhaust gas 17 discharged from the fuel reformer 5 in the configuration shown in FIG. 1 described above. a pressure detector 41 that detects the flow rate of the reformed gas flowing through the bypass line 10; a flow rate detector 42 that detects the flow rate of the reformed gas flowing through the bypass line 10; System pressure control device 4 that obtains the flow rate command value of fuel for auxiliary burner
3A, a flow rate detector 44 that detects the flow rate of the auxiliary burner fuel flowing through the auxiliary burner fuel supply line 21, a flow rate value of the auxiliary burner fuel detected by the flow rate detector 44, and a flow rate value from the system pressure control device 43A. Auxiliary burner fuel that controls the opening degree of the auxiliary burner fuel flow control valve 22 provided on the auxiliary burner fuel supply line 21 based on the deviation that is the result of comparison with the auxiliary burner fuel flow rate command value. The flow mountain control device 43B constitutes a separate system pressure system.

Next, the operation of the fuel cell power generation system configured as described above will be described.

That is, in the embodiment shown in FIG. 1 described above, the reformed gas flowing into the auxiliary burner 9 through the bypass line 10 changes the amount of combustion in the auxiliary burner 9, causing a disturbance to the system pressure illt[. In this regard, in this embodiment, the above-mentioned disturbance is detected by the flow rate detector 42 and inputted together with the detected value of the system pressure by the pressure detector 41 to the system pressure control device 43A. The fuel flow rate for the auxiliary burner is determined by subtracting the operating fuel that is calorifically equal to the disturbance fuel from the operating fuel flow rate commensurate with the deviation between the pressure detection value and the pressure setting value by 41, as the auxiliary burner fuel flow rate command value. The auxiliary burner fuel flow control device 43B controls the auxiliary burner fuel based on the deviation between the auxiliary burner fuel flow rate command value and the auxiliary burner fuel flow rate detected by the flow rate detector 44. By controlling the opening degree of the auxiliary burner fuel flow control valve 22 provided on the supply line 21 to control the flow rate of the auxiliary burner fuel, the influence of the above-mentioned disturbance can be suppressed.

FIG. 3 is a block diagram showing another configuration example of the fuel cell power generation system according to the present invention, and the same parts as in FIG. Only the different parts will be described.

That is, FIG. 3 shows a configuration in which an absorber tank 45 for absorbing pressure fluctuations is provided between the bypass flow control valve 11 and the auxiliary burner 9 on the bypass line 10 in the configuration shown in FIG. 1 described above. .

That is, in the embodiment of FIG.
As mentioned above, the reformed gas flowing into the auxiliary burner 9 through the auxiliary burner 9 changes the amount of combustion in the auxiliary burner 9 and causes a disturbance to the system pressure control. By providing this, disturbance fluctuations can be mitigated to assist in system pressure control.

In addition, the present invention is not limited to the embodiments described above, and can be implemented with various modifications without changing the gist thereof.

(Effects of the Invention) As explained above, according to the present invention, the reforming reaction catalyst can maintain the raw fuel flow rate constant in response to changes in the flow rate of fuel gas supplied to the fuel cell due to temperature control of the reforming reaction catalyst layer. It is possible to provide an extremely reliable fuel cell power generation system in which the temperature of the layer can be easily controlled and fluctuations in the system pressure caused by the pressure control of the fuel reforming system can be suppressed to the minimum possible level.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the fuel cell power generation system according to the present invention, FIGS. 2 and 3 are block diagrams showing other embodiments of the fuel cell power generation system according to the present invention, and FIG. 4 is a block diagram showing one embodiment of the fuel cell power generation system according to the present invention. A block diagram showing an example of a conventional fuel cell power generation system. Figure 5 shows the reforming reaction catalyst that occurs when the flow rate of fuel supplied to the cell for one-time control of the fuel reformer is changed in steps by conventional reforming system pressure control. It is a figure which shows the inverse response of I temperature. DESCRIPTION OF SYMBOLS 1... Raw fuel, 2... Steam supply device, 3... Raw fuel flow control valve, 4... Steam flow control valve, 5...
・Fuel reformer, 6... Reforming reaction tube, 7... High temperature shift converter, 8... Low temperature shift converter, 9... Auxiliary burner, 1o
...Bypass line, 11...Bypass flow control valve, 12...Fuel cell, 12A...Fuel electrode, 12B...
...Oxidizer electrode, 13...Fuel gas supply line, 14.
...Fuel flow control valve, 15...Fuel gas discharge line,
16...Burner, 17...High temperature exhaust gas, 18...
Oxidizing gas discharge line, 19... mixer, 20...
Air supply device, 2OA...turbine, 20B...compressor, 21...fuel supply line for auxiliary burner,
22... Auxiliary burner fuel flow control valve, 23...
Oxidizing gas flow control valve, 24... Oxidizing gas flow control valve, 25... Oxidizing gas supply line, 26... Oxidizing gas flow rate control valve, 27... System differential pressure control valve,
28... Inverter, 29... Pressure detector, 30
...pressure control device, 31...temperature detector, 32.
...Temperature control device, 33...Flow rate detector, 34...
・Flow rate control device, 35... Pressure detector, 36... System pressure control device, 37... Load current detection signal,
38A... Raw fuel flow rate calculation device, 38B... Raw fuel flow rate control device, 39... Flow rate detector, 40... Reforming system pressure control device, 41... Pressure detector, 42...・
Flow rate detector, 43A... System pressure control device, 43
B...Fuel flow rate control device for auxiliary burner, 44...Flow rate detector, 45...Absorber tank.

Claims (3)

[Claims] (1) A mixed gas of raw fuel and steam is introduced inside a reforming reaction tube in which a reforming reaction catalyst layer is provided, and combustion fuel and combustion air are combusted outside the reforming reaction tube. The air supply system consists of a fuel reformer that generates reformed gas by circulating high-temperature combustion gas obtained by combustion in a burner in the chamber, a turbine, and a compressor, and compresses air in the atmosphere to obtain compressed air. The reformed gas from the fuel reformer is introduced into the fuel electrode as a fuel gas, and the compressed air from the air supply device is introduced into the oxidizer electrode as an oxidant gas, and an electrochemical reaction occurs at this time. A fuel cell that extracts electrical energy from between both electrodes, fuel supplied via an auxiliary burner fuel supply line, and a portion of reformed gas introduced from the fuel reformer via a bypass line, an auxiliary burner that is combusted by a portion of the compressed air from the air supply device; combustion gas discharged from the auxiliary burner; exhaust gas discharged from the oxidizer electrode of the fuel cell; and exhaust gas discharged from the fuel reformer. a mixer that mixes high-temperature exhaust gas and a portion of the compressed air from the air supply device and supplies this mixed gas as driving energy for the air supply device; A fuel cell power generation device in which exhaust gas discharged from the fuel reformer is introduced as combustion fuel for the fuel reformer, and a portion of compressed air from the air supply device is introduced as combustion air for the fuel reformer. In the system, based on a comparison result between a raw fuel flow rate command value given as a function of the load current of the fuel cell and a detected flow rate value of raw fuel flowing through the raw fuel supply line, Flow control means for controlling the opening degree of a raw fuel flow control valve provided in A fuel reforming system pressure control means comprising a pressure control means for controlling the opening degree of a bypass flow control valve provided on the line; and a temperature detection value and a temperature setting value of a reforming reaction catalyst layer of the fuel reformer. and a detected flow rate value of the fuel gas flowing through the fuel gas supply line to the fuel electrode of the fuel cell, a first fuel flow rate control provided on the fuel gas supply line. a reforming reaction catalyst layer temperature control means for controlling the opening degree of a valve; a detected pressure value at a confluence point of exhaust gas discharged from the oxidizer electrode of the fuel cell and high temperature exhaust gas discharged from the fuel reformer; System pressure control means for controlling the opening degree of a second fuel flow control valve provided on the auxiliary burner fuel supply line based on a comparison result with a pressure setting value. A fuel cell power generation system. (2) Fuel cell power generation according to claim (1), characterized in that an absorber tank for absorbing pressure fluctuations is provided between the bypass flow control valve and the auxiliary burner on the bypass line. system. (3) A mixed gas of raw fuel and steam is introduced into the reforming reaction tube in which a reforming reaction catalyst layer is provided, and combustion fuel and combustion air are combusted outside the reforming reaction tube. The air supply system consists of a fuel reformer that generates reformed gas by circulating high-temperature combustion gas obtained by combustion in a burner in the chamber, a turbine, and a compressor, and compresses air in the atmosphere to obtain compressed air. The reformed gas from the fuel reformer is introduced into the fuel electrode as a fuel gas, and the compressed air from the air supply device is introduced into the oxidizer electrode as an oxidant gas, and an electrochemical reaction occurs at this time. A fuel cell that extracts electrical energy from between both electrodes, fuel supplied via an auxiliary burner fuel supply line, and a portion of reformed gas introduced from the fuel reformer via a bypass line, an auxiliary burner that is combusted by a portion of the compressed air from the air supply device; combustion gas discharged from the auxiliary burner; exhaust gas discharged from the oxidizer electrode of the fuel cell; and exhaust gas discharged from the fuel reformer. a mixer that mixes high-temperature exhaust gas and a portion of the compressed air from the air supply device and supplies this mixed gas as driving energy for the air supply device; A fuel cell power generation device in which exhaust gas discharged from the fuel reformer is introduced as combustion fuel for the fuel reformer, and a portion of compressed air from the air supply device is introduced as combustion air for the fuel reformer. In the system, based on a comparison result between a raw fuel flow rate command value given as a function of the load current of the fuel cell and a detected flow rate value of raw fuel flowing through the raw fuel supply line, Flow control means for controlling the opening degree of a raw fuel flow control valve provided in A fuel reforming system pressure control means comprising a pressure control means for controlling the opening degree of a bypass flow control valve provided on the line; and a temperature detection value and a temperature setting value of a reforming reaction catalyst layer of the fuel reformer. and a detected flow rate value of the fuel gas flowing through the fuel gas supply line to the fuel electrode of the fuel cell, a first fuel flow rate control provided on the fuel gas supply line. a reforming reaction catalyst layer temperature control means for controlling the opening degree of the valve; a detected pressure value at the confluence point of the exhaust gas discharged from the oxidizer electrode of the fuel cell and the high temperature exhaust gas discharged from the fuel reformer; A flow rate command value of auxiliary burner fuel obtained based on a pressure setting value and a detected flow rate value of reformed gas flowing through the bypass line, and a detected flow rate value of auxiliary burner fuel flowing through the auxiliary burner fuel supply line. A system pressure control means for controlling the opening degree of a second fuel flow control valve provided on the fuel supply line for the auxiliary burner based on the comparison result of the fuel cell power generation. system.