JP2006032001A - Fuel cell power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell power generation system in which an operation control without problem in an environment is performed by suppressing the generation of a carbon monoxide. <P>SOLUTION: The fuel cell power generation system includes an operation control means C for controlling a combustion air supply means 15 to control an original fuel supply means 12 for controlling to increase or decrease the amount of supply of the original fuel according to the electric load of a fuel cell 1, and to control to supply combustion air of the amount of a target corresponding to the original fuel obtained according to the amount of supply of the original fuel to a combustor 5. When the operation control means C controls to reduce the amount of supply of the original fuel, the combustion air is supplied to the combustor 5 with the amount of supply of increasing more than the amount of the target corresponding to the original fuel obtained according to the amount of supply of the original fuel. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell that generates electricity by reacting an anode gas and a cathode gas, and an anode exhaust gas discharged from the fuel cell is combusted in a combustor together with combustion air to reform the raw fuel while heating the reforming catalyst. Therefore, the reformer that generates the anode gas and the raw fuel supply means for increasing / decreasing the supply amount of the raw fuel according to the electric load of the fuel cell are controlled, and is determined according to the supply amount of the raw fuel. The present invention relates to a fuel cell power generation system provided with operation control means for controlling combustion air supply means for controlling so as to supply a target amount of combustion air corresponding to the raw fuel to the combustor.

  When the anode gas supplied to the fuel cell is generated in the reformer, reforming is performed in order to adjust the temperature of the reforming catalyst to which raw fuel such as methane and steam are supplied to a temperature suitable for the reforming reaction. The catalyst is heated by a combustor. The combustor is configured such that anode exhaust gas that is unreacted anode gas discharged from the fuel cell is burned together with combustion air, or when the anode exhaust gas is insufficient, raw fuel is supplied and burned. It is configured. In this combustor, in order to suppress the generation of carbon monoxide due to incomplete combustion, the anode exhaust gas supplied to the combustor or the amount of combustion air supplied to the amount of anode exhaust gas and raw fuel supplied are appropriately set. Need to control. Therefore, in the conventional fuel cell power generation system, based on the assumption that the amount of anode exhaust gas generated is estimated based on the amount of raw fuel supplied, the target amount of combustion air determined according to the amount of raw fuel supplied is burned. It is made to supply to a container (for example, refer patent document 1).

JP 2001-165431 A

  In the conventional fuel cell power generation system, a target amount of combustion air required according to the supply amount of raw fuel is supplied to the combustor. Therefore, when control is performed to change the electric load of the fuel cell, Simultaneously with the control for changing the electric load, the control for changing the supply amount of raw fuel and the amount of combustion air is performed. However, even if the supply load of the raw fuel is controlled to decrease at the same time as the electric load of the fuel cell is controlled to decrease, at that time, the raw fuel is generated with the supply amount before the decrease control and supplied to the fuel cell. Since the amount of unreacted anode gas increases, the amount of anode exhaust gas supplied to the combustor increases. For this reason, if the supply amount of combustion air is also controlled to decrease in accordance with the reduction control of the supply amount of raw fuel, the supply amount of combustion air becomes too small relative to the supply amount of anode exhaust gas, resulting in monoxide due to incomplete combustion. The problem of carbon generation occurs. Therefore, since the combustion exhaust gas discharged from the combustor contains carbon monoxide, it becomes a serious environmental problem.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel cell power generation system in which the generation of carbon monoxide is suppressed and environmentally-friendly operation control is performed. .

  In order to achieve the above object, a first characteristic configuration of a fuel cell power generation system according to the present invention includes a fuel cell that generates electricity by reacting an anode gas and a cathode gas, and an anode exhaust gas discharged from the fuel cell for combustion. A reformer that reforms raw fuel while combusting with a combustor and heating the reforming catalyst to generate the anode gas, and a supply amount of the raw fuel according to an electric load of the fuel cell. Combustion air supply means for controlling the raw fuel supply means for increasing / decreasing control and for controlling the supply of combustion air in a target quantity corresponding to the raw fuel obtained according to the supply quantity of the raw fuel to the combustor. An operation control means for controlling the fuel cell power generation system, wherein when the operation control means performs a decrease control on the supply amount of the raw fuel, the operation control means is obtained according to the supply amount of the raw fuel. There combustion air of more increasing the supply amount than the raw fuel corresponding target amount to a point that is configured to supply to the combustor.

According to the first characteristic configuration, when the electric load of the fuel cell is controlled to decrease, the raw fuel supply means controls to reduce the supply amount of the raw fuel, and the combustion air supply means obtains according to the supply amount of the raw fuel. The operation control means controls the raw fuel supply means and the combustion air supply means so as to supply an increased supply amount of combustion air larger than the raw fuel-corresponding target amount to the combustor.
That is, when reducing the supply amount of raw fuel in accordance with the reduction control of the electric load of the fuel cell, the unreacted portion of the anode gas supplied to the fuel cell at the time of the reduction control of the electric load of the fuel cell. In consideration of the increase in the amount of anode exhaust gas supplied to the combustor due to an increase in the amount of fuel, the target amount of raw fuel corresponding to the amount of supply of combustion air to the combustor is determined according to the amount of raw fuel supplied Will be increased to a greater increase in supply. As a result, an amount of combustion air that can completely burn the anode exhaust gas supplied to the combustor is supplied to the combustor. Therefore, incomplete combustion in the combustor is suppressed, and carbon monoxide Occurrence can be suppressed.
Accordingly, there is provided a fuel cell power generation system in which generation control of carbon monoxide is suppressed and operation control without environmental problems is performed.

  According to a second characteristic configuration of the fuel cell power generation system according to the present invention, in addition to the first characteristic configuration, the operation control means controls the increased supply amount before the supply control of the raw fuel is reduced. The combustion air is configured to be supplied to the combustor.

  According to the second characteristic configuration, before the combustion air supply means controls to reduce the electric load of the fuel cell and at the same time to reduce the supply amount of the raw fuel, that is, the fuel cell has not reacted yet. Combustion with an increased supply amount greater than the target amount corresponding to the raw fuel required according to the supply amount of raw fuel before the anode exhaust gas supplied from the fuel cell to the combustor increases due to the increase in anode gas Since the combustion air is supplied to the combustor, an amount of combustion air that can completely burn the anode exhaust gas is surely supplied to the combustor before the increased anode exhaust gas flows into the combustor. It is possible to create a state that is. As a result, incomplete combustion of the anode exhaust gas in the combustor can be reliably suppressed, and generation of carbon monoxide can be suppressed.

  According to a third characteristic configuration of the fuel cell power generation system of the present invention, in addition to the first or second characteristic configuration, the operation control means starts supplying the combustion air with the increased supply amount, and then the anode When a period in which the amount of exhaust gas discharged is greater than a reference amount corresponding to the amount of raw fuel supplied, combustion air corresponding to the amount of raw fuel required for the amount of raw fuel supplied is supplied to the combustor. The point is that it is configured to do.

  According to the third characteristic configuration, after the combustion air supply means starts supplying the increased supply amount of combustion air, a period in which the discharge amount of the anode exhaust gas is larger than the reference amount corresponding to the supply amount of the raw fuel When a period of time elapses, the combustion air in a target amount corresponding to the raw fuel required for the supply amount of the raw fuel is supplied to the combustor, and an excessive amount of combustion is performed with respect to the supply amount of anode exhaust gas to the combustor. Air is not continuously supplied to the combustor. As a result, the temperature of the reforming catalyst cannot be maintained because it is possible to prevent the heat in the combustor from being taken away by the excess combustion air that does not participate in the combustion of the anode exhaust gas, thereby hindering the temperature maintenance of the reforming catalyst. In this case, it is possible to avoid problems such as a reduction in raw fuel reforming efficiency and a corresponding decrease in fuel cell operation efficiency.

  In order to achieve the above object, a fourth characteristic configuration of a fuel cell power generation system according to the present invention includes a fuel cell that generates electricity by reacting an anode gas and a cathode gas, and an anode exhaust gas discharged from the fuel cell for combustion. A reformer that reforms raw fuel while combusting with a combustor and heating the reforming catalyst to generate the anode gas, and a supply amount of the raw fuel according to an electric load of the fuel cell. Combustion air supply means for controlling the raw fuel supply means for increasing / decreasing control and for controlling the supply of combustion air in a target quantity corresponding to the raw fuel obtained according to the supply quantity of the raw fuel to the combustor. And an operation control means for controlling the fuel cell power generation system, wherein when the operation control means controls the supply amount of the raw fuel to be reduced, the operation control means is derived based on the supply amount of the raw fuel. The discharge amount of the anode exhaust gas is derived based on the supply amount of the anode gas to the fuel cell and the consumption amount of the anode gas by the power generation reaction performed in the fuel cell. The combustion air corresponding to the exhaust gas required in accordance with the exhaust amount is supplied to the combustor.

According to the fourth characteristic configuration, when the operation control means decreases the supply amount of the raw fuel in response to the reduction control of the electric load of the fuel cell, the anode to the fuel cell is based on the supply amount of the raw fuel. The exhaust amount of the anode exhaust gas is derived based on the gas supply amount and the consumption amount of the anode gas by the power generation reaction performed in the fuel cell, and the target amount of exhaust gas corresponding to the exhaust gas corresponding target amount obtained according to the derived anode exhaust gas emission amount is derived. The raw fuel supply means and the combustion air supply means are controlled so as to supply combustion air to the combustor.
That is, when the supply amount of the raw fuel is decreased in accordance with the decrease in the electric load of the fuel cell, the unreacted portion of the anode gas supplied to the fuel cell increases when the electric load of the fuel cell is controlled to decrease. In view of the increase in the amount of anode exhaust gas supplied to the combustor, the anode exhaust gas obtained in accordance with the derived anode exhaust gas emission amount, that is, the anode exhaust gas supply amount to the combustor The combustion air corresponding to the exhaust gas corresponding to the exhaust gas is completely supplied to the combustor. As a result, the anode exhaust gas supplied to the combustor is completely combusted together with the target amount of combustion air corresponding to the exhaust gas, so that incomplete combustion in the combustor is suppressed and carbon monoxide generation is suppressed. It becomes possible.
Accordingly, there is provided a fuel cell power generation system in which generation control of carbon monoxide is suppressed and operation control without environmental problems is performed.

<First Embodiment>
The fuel cell power generation system according to the first embodiment will be described below with reference to the drawings.
FIG. 1 shows that an anode gas mainly composed of hydrogen generated by an anode gas generator R is supplied to the fuel cell 1 and the electric power generated by reacting the anode gas and the cathode gas is used for the fuel cell. It is an example of the block diagram of the fuel cell power generation system comprised so that it may supply via the power supply line L2 and the inverter 8 to the power supply line L to which the electric load apparatus 9 is connected. Although omitted in FIG. 1, air is used as the cathode gas supplied to the fuel cell 1.

  In this fuel cell power generation system, the electric load device 9 is configured to receive power supply from both the commercial system 11 and the fuel cell 1. The control unit C as an operation control unit of the fuel cell power generation system includes a commercial power measurement unit P1 provided in the commercial power supply line L1 and a fuel cell provided in the fuel cell power supply line L2. Each power is monitored using the power measuring unit P2, and the recovered power in the surplus power recovery device 10 is monitored, and a reverse power flow from the fuel cell power supply line L2 to the commercial system 11 occurs. In order to avoid this, surplus power that is generated by the fuel cell 1 but not consumed by the electric load device 9 is recovered by the surplus power recovery device 10. The surplus power recovery device 10 stores hot water in a hot water storage tank (not shown) or the like while circulating a load device such as an electric heater whose power consumption is variable under the control of the control unit C and hot water heated by the electric heater. Such a heat storage device can be combined.

The anode gas generator R includes a desulfurizer 2 for removing sulfur compounds contained in hydrocarbon-based raw fuels such as city gas (13A), and a steam generator for heating the supplied raw water to generate steam. 3, a reformer 4 that reforms desulfurized raw fuel and steam using a reforming catalyst (not shown) to generate a reformed gas mainly composed of hydrogen, and a reformer 4 The carbon monoxide converter 6 that converts carbon monoxide contained in the reformed gas produced in step 1 to carbon dioxide, and selectively oxidizes the carbon monoxide contained in a small amount in the reformed reformed gas A carbon monoxide selective oxidizer 7 is provided.
Then, the control processing of the anode gas generation processing performed in the anode gas generation device R, the control of the inverter 8 and the control of the surplus power recovery device 10 are performed by the control unit C.

  Specifically, the raw fuel is desulfurized through a raw fuel on-off valve 11 provided in the raw fuel supply passage 19 for intermittently supplying the raw fuel and a raw fuel control valve 12 for adjusting the supply amount of the raw fuel. Is supplied to the vessel 2. The reformer 4 is supplied with the desulfurized raw fuel desulfurized in the desulfurizer 2 through the desulfurized raw fuel gas supply path 20, and the steam generated by the steam generator 3 is steamed. It is supplied through a water vapor supply path 21 provided with a water vapor adjusting valve 13 for adjusting the amount. The reformer 4 is provided with a combustor 5 that heats the temperature of the reforming catalyst to a temperature preferable for the reforming reaction, and the reforming reaction proceeds in a state in which the temperature is controlled using the temperature sensor T. . In the combustor 5, anode exhaust gas, which is unreacted gas of the anode gas mainly composed of hydrogen generated by the anode gas generator R and supplied to the fuel cell 1, is supplied to the anode exhaust gas supply path 25. Air provided through the anode exhaust gas on-off valve 17 that intermittently supplies anode exhaust gas to the combustor 5 and whose flow rate was adjusted by the blower 15 was provided in the combustion air supply path 26. The air is supplied to the combustor 5 through the air on-off valve 16 that intermittently supplies the air and burned. Then, the combustion exhaust gas from the combustor 5 is discharged from the combustion exhaust gas passage 28. Further, when the combustion fuel for the combustor 5 is insufficient with only the anode exhaust gas in order to maintain the temperature of the reforming catalyst of the reformer 4, the raw fuel adjustment provided in the combustion raw fuel supply path 27 is performed. Raw fuel is supplied through valve 18.

The control unit C that performs operation control of the fuel cell power generation system configured as described above generates an amount of anode gas required for power generation in the fuel cell 1 in the anode gas generation device R. Further, the control valve 12 for raw fuel is controlled as a raw fuel supply means for increasing / decreasing the supply amount of the raw fuel according to the electric load of the fuel cell 1. Further, the control unit C is unreacted anode gas discharged from the fuel cell in order to adjust the temperature of the reforming catalyst to which desulfurized raw fuel and steam are supplied to a temperature suitable for the reforming reaction. When the anode exhaust gas and the combustion air are burned in the combustor 5, in order to suppress the generation of carbon monoxide due to incomplete combustion, the raw material having a certain relationship with the supply amount of the anode exhaust gas supplied to the combustor 5. The blower 15 is controlled as a combustion air supply means for controlling the combustion air to be supplied to the combustor 5 with a target amount corresponding to the raw fuel obtained in accordance with the fuel supply amount.
In this control, the raw fuel-corresponding target amount is determined by the raw fuel whose supply amount is adjusted by the raw fuel control valve 12 being the desulfurizer 2, reformer 4, carbon monoxide converter 6 and carbon monoxide selective oxidation. The combustion air is supplied to the fuel cell 1 as an anode gas through the combustor 7 and can be completely burned in an amount of the anode exhaust gas supplied to the combustor 5 as the anode exhaust gas not used in the power generation reaction in the fuel cell 1. It corresponds to the supply amount, and can be derived based on the internal structure of the anode gas generator R and the reaction state performed, the internal structure of the fuel cell 1 and the reaction state performed, and the flow rates of these gases.

  Further, when the control unit C controls to reduce the supply amount of the raw fuel simultaneously with the reduction control of the electric load of the fuel cell 1, the fuel cell is generated with the supply amount of the raw fuel before the reduction control at that time. Since the amount of unreacted anode gas supplied to the fuel gas increases and the amount of anode exhaust gas supplied to the combustor 5 increases, the supply of combustion air is performed in accordance with the reduction control of the raw fuel supply amount. When the amount is also controlled to decrease, the above-mentioned raw fuel required according to the amount of raw fuel supplied in order to avoid the problem that the supply amount of combustion air becomes too small and carbon monoxide is generated due to incomplete combustion. The blower 15 is controlled so as to supply an increased supply amount of combustion air larger than the corresponding target amount to the combustor 5.

FIG. 2 schematically shows the electric output of the fuel cell 1 during the reduction control of the supply amount of raw fuel, and the increase / decrease in the supply amount of anode exhaust gas and the supply amount of combustion air to the combustor 5. FIG. The transition of the concentration of carbon monoxide contained in the combustion exhaust gas discharged from the combustor 5 is also displayed.
The control unit C indicates that the electric load of the electric load device 9 is smaller than the output power of the fuel cell 1 and that the output of the fuel cell 1 should be reduced. If it determines based on monitoring results, such as the collection | recovery electric power in the electric power measurement part P2 and the surplus electric power collection | recovery apparatus 10, the inverter 8 will be controlled and the control which reduces the electric power supplied to the electric power supply line L2 for fuel cells will be performed . In the fuel cell 1, the power generation reaction between the anode gas and the cathode gas is limited to a necessary amount in conjunction with the control of the inverter 8, and the anode gas remains (that is, the anode exhaust gas that is an unreacted anode gas increases). Therefore, the control unit C controls the raw fuel control valve 12 so as to reduce the supply amount of the raw fuel, and decreases the amount of the anode gas generated by the anode gas generation device R.
In the graph shown in FIG. 2, the control unit C performs inverter 8 from time t2 to time t3 so that the fuel cell 1 that has generated power of about 97% of the rated output is operated for power generation at 75% of the rated output. The state which controlled is shown.

  Further, as described above, the control unit C avoids the problem that the supply amount of combustion air in the combustor 5 becomes too small and carbon monoxide is generated due to incomplete combustion. Is controlled to reduce the electrical load of the fuel cell 1 (that is, the output of power generation), and the blower 15 is controlled so as to increase the supply amount of combustion air to the combustor 5 from time t1. In this control, the control unit C determines how much the supply amount of the combustion air is increased, that is, a specific increase supply amount that is greater than the target amount corresponding to the raw fuel obtained according to the supply amount of the raw fuel. Regarding the values, the relationship between the raw fuel supply amount before the decrease control and the raw fuel supply amount after the decrease control, the internal structure of the anode gas generation device R and the reaction state to be performed, the internal structure of the fuel cell 1 and the flow to be performed. The value preset and stored based on the reaction state is used.

  As a result, the anode exhaust gas is completely burned in the combustor 5 when the electric load of the fuel cell 1 is controlled to decrease and at the same time the supply amount of the raw fuel is decreased. The presence of carbon is no longer confirmed.

Furthermore, the control unit C determines that the amount of anode gas that has not reacted in the fuel cell 1 has elapsed when the amount of anode exhaust gas discharged from the fuel cell 1 is longer than a reference amount corresponding to the amount of raw fuel supplied. When the reference amount is reached, the blower 15 is controlled so as to supply the combustor 5 with the combustion air of the target amount corresponding to the raw fuel obtained according to the supply amount of the raw fuel at time t3.
In this control, the supply amount of the raw fuel is adjusted by the raw fuel control valve 12 during a period in which the discharge amount of the anode exhaust gas from the fuel cell 1 is larger than the reference amount corresponding to the supply amount of the raw fuel. After that, the anode was supplied to the fuel cell 1 as an anode gas through the desulfurizer 2, the reformer 4, the carbon monoxide converter 6 and the carbon monoxide selective oxidizer 7, and was not used for the power generation reaction in the fuel cell 1. This corresponds to the period required until the exhaust gas is supplied to the combustor 5, and the internal structure of the anode gas generation device R and the reaction state performed, the internal structure of the fuel cell 1 and the reaction state performed, and the flow rates of these gases Can be derived on the basis of
As a result, since it is possible to prevent heat in the combustor 5 from being taken away by excess combustion air that is not involved in the combustion of the anode exhaust gas, the temperature of the reforming catalyst can be prevented from being maintained. It is possible to avoid problems such as a decrease in the reforming efficiency of the raw fuel that occurs when it cannot be performed and a decrease in the operation efficiency of the fuel cell that accompanies it.

A comparative example of the fuel cell power generation system of the first embodiment will be described below with reference to FIG.
In this comparative example, as in the conventional fuel cell power generation system, as shown in FIG. 3, when the control unit C controls to reduce the electric load of the fuel cell 1 and simultaneously controls to reduce the supply amount of raw fuel, The supply amount of combustion air is controlled to decrease at the time. As a result, at the time when the supply amount of the raw fuel is reduced and controlled in accordance with the reduction control of the electric load of the fuel cell 1, the anode generated by the supply amount of the raw fuel before the reduction control and supplied to the fuel cell Since the amount of unreacted gas in the gas increases and the supply amount of anode exhaust gas supplied to the combustor increases, the supply amount of combustion air that is controlled to decrease becomes too small, and the combustion exhaust gas from the combustor 5 is reduced. In FIG. 3, carbon monoxide generated by incomplete combustion appears.

Second Embodiment
In the fuel cell power generation system of the second embodiment, when the control unit C controls to reduce the electric load of the fuel cell 1 and simultaneously controls to reduce the supply amount of the raw fuel, it is discharged from the fuel cell 1 and combustor. The supply amount of the anode exhaust gas (unreacted anode gas in the fuel cell 1) supplied to the fuel cell 5 is derived, and combustion air corresponding to the derived supply amount of the anode exhaust gas is supplied to the combustor 5. This is different from the fuel cell power generation system described in the first embodiment. The fuel cell power generation system of the second embodiment will be described below, but the description of the same configuration as that of the first embodiment will be omitted.

The flowchart shown in FIG. 4 shows the control of the control unit C from the control for reducing the electric load of the fuel cell 1 to the supply control of the combustion air.
The control unit C indicates that the electric load of the electric load device 9 is smaller than the output power of the fuel cell 1 and that the output of the fuel cell 1 should be reduced. If it determines based on monitoring results, such as the collection | recovery electric power in the electric power measurement part P2 and the surplus electric power collection | recovery apparatus 10, the inverter 8 will be controlled and the control which reduces the electric power supplied to the electric power supply line L2 for fuel cells will be performed . In step 102, the control unit C supplies the fuel cell 1 with an amount of anode gas necessary for the power generation reaction in the fuel cell 1, so that the amount of raw fuel supplied to the anode gas generator R decreases. Thus, the control valve 12 for raw fuel is controlled.

  Next, in step 104, the control unit C, based on the supply factor of the raw fuel to the anode gas generator R and the variation factor of the reforming reaction such as the temperature of the reforming catalyst monitored by the temperature sensor T, The supply amount of the anode gas supplied from the anode gas generator R to the fuel cell 1 is derived. Further, since the control unit actively controls the inverter 8 to reduce the power supplied to the fuel cell power supply line L2, it is consumed for the power generation reaction in the fuel cell 1. The amount of anode gas consumed can also be derived.

In step 106, the control unit C discharges the anode exhaust gas from the fuel cell 1 to the combustor 5 based on the supply amount of the anode gas to the fuel cell 1 and the consumption amount of the anode gas derived as described above. In step 108, the blower 15 is controlled so as to supply the combustion air with the target amount of exhaust gas corresponding to the exhaust amount corresponding to the discharge amount of the anode exhaust gas to the combustor. In this control, the target amount corresponding to exhaust gas corresponds to the amount of combustion air that can completely burn the amount of anode exhaust gas derived as described above in the combustor 5, and the control unit C is set in advance. Use the stored value.
As a result, as in the case of the first embodiment, the anode exhaust gas is completely burned in the combustor 5 when the electric load of the fuel cell 1 is controlled to decrease and simultaneously the supply amount of raw fuel is controlled to decrease. Thus, incomplete combustion of the anode exhaust gas is suppressed in the combustor 5, and it becomes possible to prevent carbon monoxide from being included in the combustion exhaust gas of the combustor 5.

<Another embodiment>
<1>
In the above embodiment, the control of the supply amount of combustion air when the anode exhaust gas is combusted together with the combustion air in the combustion unit 5 has been described. However, in the combustion unit 5, the raw fuel and the anode exhaust gas are combusted together with the combustion air. Also good.
When the raw fuel and the anode exhaust gas are burned together with the combustion air in the combustion unit 5, the control unit C uses the amount of combustion air required to completely burn the anode exhaust gas in the combustor 5 in the same manner as in the above embodiment. Can be derived as the target amount corresponding to the raw fuel. On the other hand, the control unit C adjusts the supply amount of the raw fuel to the combustor 5 by controlling the raw fuel control valve 18, so that the raw fuel supplied to the combustor 5 is completely burned. The amount of combustion air required can be derived. Therefore, even when the raw fuel and anode exhaust gas are burned together with the combustion air in the combustion section 5, the amount of combustion air required to completely burn the raw fuel and anode exhaust gas supplied to the combustor 5 Can be derived.
In addition, when the reduction control of the supply amount of the raw fuel is performed simultaneously with the reduction control of the electric load of the fuel cell 1 described in the above embodiment, the target amount corresponding to the raw fuel calculated according to the supply amount of the raw fuel is used. The value of the increased supply amount and the value of the target amount corresponding to exhaust gas can be derived in the same manner. Specifically, the amount of combustion air necessary to completely burn the raw fuel supplied to the combustor 5 is derived separately as described above, and the anode exhaust gas supplied to the combustor 5 is completely burned. What is necessary is just to add to the quantity of combustion air required in order to make it.

<2>
In the above embodiment, the control unit C is configured to control the inverter 8 to reduce the electric load of the fuel cell 1 and simultaneously to reduce the supply amount of raw fuel for generating the anode gas. However, the timing for reducing the electric load of the fuel cell 1 and the timing for reducing the supply amount of the raw fuel for generating the anode gas may be mixed in time rather than simultaneously. . In addition, as described above, it is preferable to supply the increased supply amount of combustion air to the combustor 5 prior to the decrease control of the supply amount of the raw fuel. However, the increased supply amount of combustion air may be supplied to the combustor 5 at a timing close to time.

Block diagram of fuel cell power generation system The figure which shows the supply amount control of the combustion air of this embodiment The figure which shows the supply amount control of the combustion air of a comparative example Flow chart of combustion air supply amount control

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell 4 Reformer 5 Combustor 12 Control valve for raw fuel (raw fuel supply means)
15 Blower (combustion air supply means)
C control unit (operation control means)

Claims (4)

A fuel cell that generates electricity by reacting an anode gas and a cathode gas; and
A reformer for generating anode gas by reforming raw fuel while heating the reforming catalyst by combusting anode exhaust gas discharged from the fuel cell together with combustion air in a combustor;
A raw fuel supply means for increasing or decreasing the supply amount of the raw fuel according to the electric load of the fuel cell is controlled, and a target amount of combustion air corresponding to the raw fuel required for the supply amount of the raw fuel is obtained. A fuel cell power generation system provided with operation control means for controlling combustion air supply means for controlling to supply to the combustor,
When the operation control means controls to decrease the supply amount of the raw fuel, the combustion air is supplied to the combustor with an increased supply amount that is larger than the target amount corresponding to the raw fuel obtained in accordance with the supply amount of the raw fuel. A fuel cell power generation system configured to.   2. The fuel cell power generation according to claim 1, wherein the operation control means is configured to supply the increased supply amount of combustion air to the combustor prior to reducing the supply amount of the raw fuel. system.   After the operation control means starts to supply the increased supply amount of combustion air, when a period in which the discharge amount of the anode exhaust gas is larger than a reference amount corresponding to the supply amount of the raw fuel elapses, the raw fuel The fuel cell power generation system according to claim 1 or 2, wherein the combustion air is supplied to the combustor with a target amount corresponding to a raw fuel obtained in accordance with a supply amount of the fuel. A fuel cell that generates electricity by reacting an anode gas and a cathode gas; and
A reformer for generating anode gas by reforming raw fuel while heating the reforming catalyst by combusting anode exhaust gas discharged from the fuel cell together with combustion air in a combustor;
A raw fuel supply means for increasing or decreasing the supply amount of the raw fuel according to the electric load of the fuel cell is controlled, and a target amount of combustion air corresponding to the raw fuel required for the supply amount of the raw fuel is obtained. A fuel cell power generation system provided with operation control means for controlling combustion air supply means for controlling to supply to the combustor,
The operation control means is
When the supply amount of the raw fuel is controlled to decrease, the supply amount of the anode gas to the fuel cell derived based on the supply amount of the raw fuel, and the anode gas generated by a power generation reaction performed in the fuel cell The discharge amount of the anode exhaust gas is derived based on the consumption amount of the exhaust gas, and the combustion air of the target amount corresponding to the exhaust gas calculated according to the derived discharge amount of the anode exhaust gas is supplied to the combustor. Fuel cell power generation system.

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