JP3986430B2 - Hydrogen utilization system using solid oxide fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrogen utilization system in which a hydrogen utilization device is provided in addition to a solid oxide fuel cell.
[0002]
[Prior art]
Conventionally, a system has been proposed in which a solid oxide fuel cell (SOFC) is provided with a hydrogen utilization device that performs an action utilizing hydrogen. One of the general features of such a system is that the use efficiency is increased by providing the SOFC and the hydrogen utilization device separately from each other.
[0003]
This is mainly because the exhaust fuel of SOFC can be used in the hydrogen utilization device. Further, when the hydrogen utilization device is a fuel cell that generates power using hydrogen as a fuel, the fuel cell is a combination of fuel cells, so that the power generation system is clean, environmentally friendly, and has low noise.
[0004]
Examples of hydrogen utilization devices include phosphoric acid fuel cells (PAFC) and polymer electrolyte fuel cells (PEFC) as fuel cells that generate electricity using hydrogen as fuel, and other examples include hydrogen gas turbines and hydrogen storage devices. It is done. A solid oxide fuel cell is synonymous with a solid oxide fuel cell. The following are points to note when installing a hydrogen utilization device in SOFC.
[0005]
First, in a hydrogen utilization device, natural gas (a hydrocarbon mainly composed of methane), which is a raw fuel, cannot be used directly. Therefore, it is necessary to convert or reform it into hydrogen before introducing it into the hydrogen utilization device. is there. Here, reforming means, for example, from methane, which is a main component of natural gas, to H by steam.₂It is the following reaction to obtain (hydrogen) and CO (carbon monoxide).
CH_Four+ H₂O → CO + 3H₂
[0006]
At this time, H in SOFC₂, CO can be used as fuel.₂Can only be used. In particular, in the case of a fuel cell that generates power using hydrogen as a fuel, if CO is introduced into the fuel cell, the platinum catalyst is poisoned by the CO and cannot generate power. Therefore, it is necessary to reduce the amount of CO introduced into the hydrogen utilization device.
[0007]
On the other hand, it is necessary to increase the fuel utilization rate by effectively using the SOFC waste fuel, and to improve the power generation efficiency and the overall efficiency. Therefore, it is necessary to convert unused CO contained in the exhaust fuel or CO obtained by reforming the raw fuel described above into hydrogen, that is, to transform it. Here, transformation means that CO is converted into CO by steam.₂(Carbon dioxide), H₂It is the following reaction to convert to.
CO + H₂O → CO₂+ H₂
[0008]
In addition, it is necessary to increase the fuel utilization rate by arranging the fuel circulation system, and to improve the power generation efficiency and the overall efficiency. Further, the operating temperature of SOFC is about 900 ° C., whereas the operating temperature of PEFC is about 80 ° C., for example. Thus, since the difference in operating temperature may be very large, it is necessary to configure the system with a heat system with little heat loss, such as an optimal heat exchanger arrangement.
[0009]
As a system as described above, for example, a hybrid fuel cell power generator is disclosed (see, for example, Patent Document 1). This is mainly composed of a reformer that reforms a hydrocarbon-based or alcohol-based raw fuel into a gas containing hydrogen and carbon monoxide, and a gas reformed by the reformer and supplied with the reformer. A first fuel cell that generates power using both carbon oxides as fuel and a polymer electrolyte fuel cell to which exhaust gas from the fuel electrode of the first fuel cell is supplied as fuel gas are provided.
[0010]
Also, a hybrid fuel cell system is disclosed (see, for example, Patent Document 2). This is because, as a main configuration, a steam reformer that generates a reformed gas mainly composed of hydrogen from hydrocarbon gas is disposed in the vicinity of the solid oxide fuel cell disposed in the heat insulating container, and the solid electrolyte type A solid oxide fuel cell is obtained by utilizing the residual heat generated in the fuel cell for heating the steam reformer and disposing the polymer electrolyte fuel cell outside the heat insulating container on the downstream side of the steam reformer. It is characterized in that power generation by a polymer electrolyte fuel cell is performed in addition to power generation by.
[0011]
[Patent Document 1]
JP-A-8-306369
[Patent Document 2]
JP 2001-266924 A
[0012]
[Problems to be solved by the invention]
However, the configuration described in Patent Document 1 requires an external reformer, and an external reformer is disposed immediately before the SOFC (reformer 1). However, in order to operate the external reformer, a heat source is required, so that heat loss increases.
[0013]
Further, the amount of CO introduced into the PEFC is controlled by circulating the exhaust fuel at the SOFC outlet (by the return flow path 13) to the SOFC inlet. However, since it is very difficult to selectively circulate only CO, its control is difficult. That is, the CO concentration in the gas becomes the same no matter how it is controlled.
[0014]
In addition, as described above, there is a fuel recirculation system around the SOFC for the purpose of reducing the amount of CO introduced into the PEFC, but since there is no fuel recirculation system for the purpose of improving the fuel utilization rate, the power generation efficiency is lowered. .
[0015]
In the configuration described in Patent Document 2, an external reformer is similarly required, and an external reformer is disposed immediately before the SOFC (preliminary reformer A, reformer B). ). However, as described above, in order to operate the external reformer, a heat source is required, so that heat loss increases.
[0016]
In addition, part of the SOFC exhaust fuel and raw fuel are supplied to the PEFC via a reformer, a shift reactor, and the like (CO converter). The remaining SOFC exhaust fuel that is not supplied to the PEFC is used to keep the external reformer warm by burning it. For this reason, the fuel is not effectively used for power generation, and the fuel utilization rate is low, so the power generation efficiency is also low. Furthermore, since there is no fuel recirculation system, the fuel utilization rate is not improved and the power generation efficiency is lowered.
[0017]
In view of such problems, the present invention provides a hydrogen utilization system using a solid oxide fuel cell that has a high fuel utilization rate and further improves the overall efficiency including power generation efficiency and heat utilization rate. The purpose is to do.
[0018]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a solid oxide fuel cell that generates power using the fuel while reforming the fuel into a gas containing hydrogen and carbon monoxide;
A CO converter that converts carbon monoxide contained in the exhaust fuel from the solid oxide fuel cell into hydrogen, and the exhaust fuel from the solid oxide fuel cell is recycled to the solid oxide fuel cell. A system having a first recirculation system and a second recirculation system that recirculates from the latter stage of the CO transformer to the first recirculation system;
And a hydrogen utilization device that performs an action utilizing hydrogen contained in the exhaust fuel from the solid oxide fuel cell.
[0019]
In addition, a solid oxide fuel cell that generates power using the fuel while reforming the fuel into a gas containing hydrogen and carbon monoxide, and an action utilizing hydrogen contained in the exhaust fuel from the solid oxide fuel cell A hydrogen utilization device for performing
At least one of the exhaust fuel and the exhaust air from the solid oxide fuel cell is provided with a combustor that is partially branched and mixed with the other to burn.
[0020]
Further, a solid oxide fuel cell that generates power using the fuel while reforming the fuel into a gas containing hydrogen and carbon monoxide, and carbon monoxide contained in the exhaust fuel from the solid oxide fuel cell is converted to hydrogen. A CO converter that converts to hydrogen, and a hydrogen utilization device that operates using hydrogen contained in the exhaust fuel from the solid oxide fuel cell,
At least one of the exhaust fuel and the exhaust air from the solid oxide fuel cell is provided with a combustor that is partially branched and mixed with the other to burn.
[0021]
Further, the present invention is characterized in that a heat recovery device for recovering exhaust heat generated in the solid oxide fuel cell is provided. Further, the present invention is characterized in that a heat recovery device for recovering exhaust heat generated in the CO transformer is provided. In addition, a heat recovery device that recovers exhaust heat generated in the combustor is provided. The hydrogen utilization device may be a fuel cell, a hydrogen gas turbine, or a hydrogen storage device that generates electricity using hydrogen as a fuel.
[0022]
Further, the predetermined state quantities in the solid oxide fuel cell and the hydrogen utilization device are controlled in cooperation with a thermoelectric ratio command for feedforward control. The predetermined state quantities are the fuel side inlet temperature, the air side inlet temperature, the inlet fuel side, the air side pressure difference in the solid oxide fuel cell, and the fuel side inlet temperature in the hydrogen utilization device. And the air side inlet temperature, and the inlet fuel side and air side pressure difference.
[0023]
Further, as the predetermined state quantities, a combustor that mixes and burns an inlet temperature of a CO converter disposed immediately before the hydrogen utilization device and exhaust fuel and exhaust air from the solid oxide fuel cell. The outlet temperature is added. Further, the thermoelectric ratio command is changed by manipulating a distribution ratio of a branch portion where the exhaust fuel from the solid oxide fuel cell branches to the CO converter and the combustor.
[0024]
In addition, the drive gas flow rate of the ejector for recirculating the exhaust fuel from the solid oxide fuel cell is switched depending on the operation mode.
[0025]
In addition, the hydrogen utilization device is a gas turbine, and the predetermined state quantities include a fuel side inlet temperature and an air side inlet temperature, and an inlet fuel side and air side pressure difference in the solid oxide fuel cell, And the turbine inlet temperature. In addition, as the predetermined state quantities, an outlet temperature of a combustor for mixing and burning exhaust fuel and exhaust air from the solid oxide fuel cell is added.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. In the present invention, in order to solve the above-mentioned considerations and problems of the prior art when the hydrogen utilization device is provided in the SOFC, the following system configuration is adopted.
[0027]
1. Reforming is performed inside the SOFC and does not require an external reformer
2. A system in which a CO transformer is arranged on the inlet side of the hydrogen utilization device to reduce the amount of CO to the hydrogen utilization device
3. A system that uses SOFC exhaust fuel as the fuel for hydrogen utilization equipment
4). System for providing a fuel recirculation system
5. A heat system incorporating the above 1 to 4 and composed of efficient heat recovery equipment
[0028]
FIG. 1 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a first embodiment of the present invention. This figure shows a basic system that employs an ejector system for SOFC fuel recirculation. In the figure, the supplied fuel (for example, natural gas) is heated by exchanging heat with exhaust fuel, which will be described later, in the regenerative heat exchanger 1 and introduced into the SOFC 3 through the ejector 2. The fuel temperature immediately before introduction is about 900 ° C., which is the operating temperature of SOFC.
[0029]
In the SOFC 3, the fuel is internally reformed and a cell reaction is performed with air described later. Due to the heat generated at this time, the exhausted fuel from the SOFC 3 is about 1000 ° C. Part of the exhausted fuel from the SOFC 3 returns to the ejector 2 due to negative pressure and is recirculated to the SOFC 3. The remainder of the exhausted fuel is cooled by exchanging heat with air in the fuel cooler 4, and further cooled by exchanging heat with fuel in the regenerative heat exchanger 1, and introduced into the CO converter 5. The exhaust fuel temperature immediately before introduction is about 350 ° C. to 450 ° C., which is the operating temperature of the CO transformer.
[0030]
The exhaust fuel transformed by the CO transformer 5 is condensed by the condenser 6 to remove moisture, and then partly mixed with new fuel via a gas recirculation fan (GRF) 7 and recirculated to the SOFC 3. Is done. This is performed in order to improve the fuel utilization rate and to secure the pressure for driving the ejector 2. The remaining exhaust fuel is introduced into the hydrogen utilization device 8.
[0031]
On the other hand, the air supplied to this system is heated by exchanging heat with the exhaust fuel in the fuel cooler 4 via the pushing fan (FDF) 9, and further exchanging heat with the exhaust air from the SOFC 3 in the high-temperature air preheater 10. Then, it is heated and introduced into SOFC3. In SOFC3, a cell reaction is performed with fuel as described above. The exhausted air from the SOFC 3 is cooled by exchanging heat with the supplied air in the high-temperature air preheater 10 and is discharged from the chimney 11 to the atmosphere.
[0032]
In the figure, * 1 branching immediately after the regenerative heat exchanger 1 and * 2 branching immediately after the high-temperature air preheater 10 are paths for taking out SOFC exhaust fuel and exhaust air, respectively. It is a system used for an increase operation system. This is similarly provided in the following embodiments. In addition, when the hydrogen utilization device 8 is a PEFC, a separate humidifier is required to maintain an internal saturated water-containing state.
[0033]
FIG. 2 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a second embodiment of the present invention. In the present embodiment, in addition to the configuration of the first embodiment shown in FIG. 1, an exhaust heat recovery device is incorporated so that heat can be used for air conditioning and hot water supply.
[0034]
Specifically, heat from the reaction in the CO transformer 5 is taken into water or air, and this heat is recovered by the exhaust heat recovery device 12, and then the remaining water (water vapor) or air is discharged from the chimney 13 to the atmosphere. Further, an exhaust heat recovery device 14 is provided between the high temperature air preheater 10 and the chimney 11, and the heat in the exhaust air from the high temperature air preheater 10 is recovered by the exhaust heat recovery device 14.
[0035]
FIG. 3 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a third embodiment of the present invention. In this embodiment, the fuel supply position is different from that of the first embodiment shown in FIG. Specifically, the fuel is supplied from a position immediately before a part of the exhaust fuel from the SOFC 3 returns to the ejector 2. Thereby, the suction flow rate of the gas to the ejector 2 can be increased. Further, by combining the configurations of the first and third embodiments, it is possible to adjust the gas flow rate to the ejector 2 and thus to the SOFC 3.
[0036]
FIG. 4 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a fourth embodiment of the present invention. In the present embodiment, in addition to the configuration of the third embodiment shown in FIG. 3, an exhaust heat recovery device is incorporated so that heat can be used for air conditioning and hot water supply.
[0037]
Specifically, in the same manner as the configuration of the second embodiment shown in FIG. 2 above, heat from the reaction in the CO transformer 5 is taken into water or air, and this heat is recovered by the exhaust heat recovery device 12. Thereafter, the remaining water (water vapor) or air is discharged from the chimney 13 to the atmosphere. Further, an exhaust heat recovery device 14 is provided between the high temperature air preheater 10 and the chimney 11, and the heat in the exhaust air from the high temperature air preheater 10 is recovered by the exhaust heat recovery device 14.
[0038]
FIG. 5 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a fifth embodiment of the present invention. In the present embodiment, the positions of the regenerative heat exchanger 1 and the fuel cooler 4 are exchanged on the fuel side and the exhaust from the SOFC 3 is exchanged on the air side with respect to the configuration of the first embodiment shown in FIG. A heat exchanger 15 is installed between the fuel and the inlet air to the SOFC 3. As a result, the heat utilization rate (heat exchange rate) in the system is increased, the SOFC 3 can be operated at a high temperature, and the power generation efficiency is increased.
[0039]
Further, in the same manner as described above, the exhaust heat recovery devices 12 and 14 are incorporated so that heat can be used for air conditioning and hot water supply. The same applies to the following embodiments. In addition, a condenser 19 is inserted between the heat exchanger 15 and the hydrogen utilization device 8.
[0040]
FIG. 6 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a sixth embodiment of the present invention. In the present embodiment, the fuel cooler and the heat exchanger are omitted from the configuration of the fifth embodiment shown in FIG. 5 above, and the system is simplified and the cost is reduced.
[0041]
FIG. 7 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a seventh embodiment of the present invention. This figure shows a system that employs a high-temperature recirculation fan system for SOFC fuel recirculation. In the present embodiment, a gas recirculation fan 16 corresponding to a high temperature is provided instead of the ejector 2 to recirculate the fuel with respect to the configuration of the first embodiment shown in FIG.
[0042]
Here, the regenerative heat exchanger and the fuel cooler are unnecessary, and the system is simplified and the cost is reduced. Further, before the exhaust fuel from the SOFC 3 is introduced into the hydrogen utilization device 8, the heat recovery is performed by the exhaust heat recovery device 17 so that the heat can be used for air conditioning and hot water supply.
[0043]
However, in order to suppress overheating of the recirculated fuel, a temperature regulator 18 such as air cooling or water cooling is provided immediately after the gas recirculation fan 16. The same applies to the eighth, eleventh, and twelfth embodiments described later. Alternatively, although not shown, a heat exchanger may be inserted between the fuel side inlet and the air side inlet of the SOFC 3 instead of the temperature regulator 18. As a result, the heat of the recirculated fuel can be used, the fuel-side and air-side inlet temperatures of the SOFC 3 can be made uniform, and the size of the high-temperature air preheater 10 can be reduced.
[0044]
FIG. 8 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to an eighth embodiment of the present invention. In the present embodiment, a fuel cooler 4 is provided in place of the exhaust heat recovery device 17 with respect to the configuration of the seventh embodiment shown in FIG. 7, and the air introduced into the SOFC 3 is heat exchanged with the exhaust fuel. It is set as the structure heated by doing. As a result, the SOFC 3 can be operated at a high temperature, and the power generation efficiency is improved.
[0045]
FIG. 9 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a ninth embodiment of the present invention. In the present embodiment, a normal recirculation fan 7 is employed for SOFC fuel recirculation as compared with the configuration of the seventh embodiment shown in FIG. Thereby, an inexpensive fan can be used. However, the regenerative heat exchanger 1 and the condenser 19 are required.
[0046]
FIG. 10 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a tenth embodiment of the present invention. In the present embodiment, a fuel cooler 4 is provided in place of the exhaust heat recovery device 17 with respect to the configuration of the ninth embodiment shown in FIG. 9, and the air introduced into the SOFC 3 is exchanged with the exhaust fuel for heat exchange. It is set as the structure heated by doing. As a result, the SOFC 3 can be operated at a high temperature, and the power generation efficiency is improved.
[0047]
FIG. 11 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to an eleventh embodiment of the present invention. In the present embodiment, in addition to the configuration of the seventh embodiment shown in FIG. 7 above, a configuration in which the hydrogen-rich gas at the CO transformer 5 outlet is partially returned to the fuel recirculation system and supplied to the SOFC 3 side. It is said. Thereby, a fuel utilization rate improves.
[0048]
FIG. 12 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a twelfth embodiment of the present invention. In this embodiment, in addition to the configuration of the eighth embodiment shown in FIG. 8 above, the hydrogen-rich gas at the CO converter 5 outlet is partially returned to the fuel recirculation system and supplied to the SOFC 3 side. It is configured. Thereby, a fuel utilization rate improves.
[0049]
In the eleventh or twelfth embodiment, by setting the return system from the CO transformer 5 outlet to the return system from the condenser 6 outlet, it is possible to remove excess moisture from the gas to be returned, Increases SOFC efficiency. Further, since the cooling can be performed, the temperature controller 18 becomes unnecessary.
[0050]
FIG. 13 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a thirteenth embodiment of the present invention. In the present embodiment, in addition to the configuration of the ninth embodiment shown in FIG. 9 described above, a configuration in which hydrogen-rich gas at the CO transformer 5 outlet is partially returned to the fuel recirculation system and supplied to the SOFC 3 side. It is said. Thereby, a fuel utilization rate improves.
[0051]
FIG. 14 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a fourteenth embodiment of the present invention. In this embodiment, in addition to the configuration of the tenth embodiment shown in FIG. 10 above, a configuration in which hydrogen-rich gas at the CO converter 5 outlet is partially returned to the fuel recirculation system and supplied to the SOFC 3 side. It is said. Thereby, a fuel utilization rate improves.
[0052]
In each of the above-described embodiments, the CO transformer 5 is used. However, when a device that does not require the purity of hydrogen is used as the hydrogen utilization device 8, such a CO transformer is preferably used. It is not necessary. Further, the fuel supply position and the branch position of the SOFC exhaust fuel and exhaust air are not limited to the positions shown in the above embodiments.
[0053]
FIG. 15 is a system diagram of a heat supply increase operation system added to the hydrogen utilization system using the solid oxide fuel cell of the present invention. As shown in the figure, in this example, in the first to fourteenth embodiments, part or all of the SOFC exhaust fuel from the path indicated by * 1, and the SOFC exhaust air from the path indicated by * 2. Mix part or all of And after burning this with the combustor 20 and collect | recovering the exhaust heat of the obtained high temperature gas with the exhaust heat recovery apparatus 21, this gas is discharge | released from the chimney 22 to air | atmosphere. Thereby, the heat supply amount to air conditioning, hot water supply, etc. can be increased.
[0054]
FIG. 16 is a system diagram of a control system applicable to a hydrogen utilization system using the solid oxide fuel cell of the present invention. This figure illustrates the case of controlling a system that employs an ejector system for SOFC fuel recirculation. And as a hydrogen utilization apparatus, fuel cells other than SOFC are used. Furthermore, the heat supply amount increasing operation system is added. In the figure, Qin indicated by an arrow indicates heat input, and Qout indicates heat output. In addition, # 1 to # 6 indicate a fuel or air supply or recirculation system and a gas flow rate thereof.
[0055]
In this system, there are the following eight state quantities as main control quantities.
(1) SOFC fuel side inlet temperature
(2) SOFC air side inlet temperature
(3) Pressure difference between SOFC inlet fuel side and air side
▲ 4 ▼ Hydrogen side equipment fuel side inlet temperature
(5) Hydrogen side air inlet temperature
▲ 6 ▼ Hydrogen side inlet fuel side, air side pressure difference
(7) Combustor outlet temperature
▲ 8 ▼ CO transformer inlet temperature
Further, in a system using a gas turbine as a hydrogen utilization device, the turbine inlet temperature becomes a controlled variable instead of the above (4), (5), (6), and (8).
[0056]
In the figure, the fuel supplied from # 1 is heated by the heat input amount Qin1, and is introduced into the SOFC 3 through the ejector 2. Exhaust fuel from the SOFC 3 is branched at the branch portion 31, and a part thereof returns to the ejector 2 due to negative pressure and is recirculated to the SOFC 3. Further, the remainder of the exhausted fuel is further branched at the branching portion 32, and a part thereof is cooled by the heat output amount Qout 3 and introduced into the CO converter 5.
[0057]
The exhaust fuel transformed by the CO transformer 5 is cooled by the heat output Qout4 and then branched by the branching part 34, and partly from # 3 through the gas recirculation fan 7 and from the # 1 by the mixing part 41 It is mixed with fresh fuel and recycled to SOFC3. The remaining exhaust fuel is introduced into the hydrogen utilization device 8.
[0058]
On the other hand, the air supplied from # 2 is heated by the heat input amount Qin2 through the pushing fan 9 and introduced into the SOFC 3. Exhaust air from the SOFC 3 is cooled by the heat output amount Qout1 and branched at the branching portion 33. Then, a part is further cooled by the amount of heat output Qout2, and further branched by the branching part 37. A part is mixed with fresh fuel from # 1 by the mixing part 41 from the gas recirculation fan 7 from # 6, Recirculated to SOFC3. Alternatively, it is released into the atmosphere from the chimney as will be described later. Further, the remaining exhaust fuel branched at the branching portion 37 is introduced into the hydrogen utilization device 8.
[0059]
In addition, the remaining exhausted fuel branched at the branching portion 32 described above is introduced into the combustor 20 from * 1. Further, the remaining exhausted air branched at the branching portion 33 described above is introduced into the combustor 20 from * 2. These are mixed and burned in the combustor 20, and the obtained high temperature gas is cooled by Qout5, that is, exhaust heat is recovered. Further, this gas is branched at the branching portion 36, and a part thereof is mixed with fresh fuel from # 1 from the # 5 through the gas recirculation fan 7 and recirculated to the SOFC 3. Further, the remaining gas is mixed with the exhausted air from # 6 in the mixing unit 42 and released into the atmosphere from the chimney.
[0060]
In addition, the exhausted fuel from the hydrogen utilization device 8 is branched at the branching portion 35, and a part thereof is mixed with new fuel from # 1 at the mixing portion 41 via the gas recirculation fan 7 from # 4 to the SOFC 3. And recirculated.
[0061]
Hereinafter, the control content of this control system is demonstrated. FIG. 17 is a block diagram of the present control system. As shown in the figure, here, the thermoelectric ratio command of the SOFC exhaust fuel is used as a preceding signal of FF (feed forward) control. Here, the thermoelectric ratio includes the concepts of both the power generation ratio of the SOFC and the hydrogen utilization device (other fuel cells) and the ratio of heat generation and power generation including heat generation in the CO converter and the combustor. Yes.
[0062]
When the FF control 51 is performed in response to the thermoelectric ratio command, the target values for the control amounts (1) to (8) are determined. At this time, in order to perform the FB (feedback) control 52 so that the actual observed amount of (1) to (8) matches the target value, the manipulated variables indicated by Qin, Qout, and # are changed. Specific examples thereof are shown in the following examples.
[0063]
[Example 1]
The SOFC fuel side inlet temperature of (1) is adjusted by the heat input amount Qin1. Qin1 may be from an external heat source such as an electric heater or from heat recovery from a high temperature part in the system. Incidentally, in each of the above embodiments, a regenerative heat exchanger or a high-temperature recirculation fan is used. According to this embodiment, the SOFC fuel side inlet temperature control can be performed.
[0064]
[Example 2]
The SOFC air side inlet temperature of (2) is adjusted by the heat input amount Qin2. Qin2 may be from an external heat source such as an electric heater or from heat recovery from a high temperature part in the system. Incidentally, in each said embodiment, it mainly uses the high temperature air preheater. According to this embodiment, SOFC air side inlet temperature control can be performed.
[0065]
Example 3
The pressure difference between the SOFC inlet fuel side and the air side in (3) is adjusted by the air flow rate # 2 or the ejector drive gas flow rate (# 3or # 4or # 5or # 6). This embodiment enables SOFC inlet differential pressure control.
[0066]
Example 4
The hydrogen utilization device fuel side inlet temperature of (4) is adjusted by the amount of heat output Qout4. Qout4 may be an external cooler or boiler, or may be a heat release to the low temperature part of the system. Incidentally, in each said embodiment, it is mainly based on the condenser. According to this embodiment, the fuel side inlet temperature control of the hydrogen utilization device can be performed.
[0067]
Example 5
The hydrogen utilization device air side inlet temperature of (5) is adjusted by the heat output amount Qout2. Qout2 may be an external cooler or boiler, or may be a heat release to the low temperature part of the system. According to the present embodiment, the hydrogen utilization device air side inlet temperature control can be performed.
[0068]
Example 6
The difference in pressure between the hydrogen side inlet fuel side and air side of (6) is adjusted by the air flow rate # 6. According to this embodiment, the hydrogen utilization device inlet differential pressure control can be performed.
[0069]
Example 7
The combustor outlet temperature of (7) is adjusted by the heat output Qout5. Qout5 may be an external cooler or boiler, or may be a heat release to the low temperature part of the system. Incidentally, in the embodiment shown in FIG. 15, the exhaust heat recovery device is used. According to the present embodiment, the combustor outlet temperature can be controlled.
[0070]
Example 8
The CO transformer inlet temperature of (8) is adjusted by the heat output Qout3. Qout3 may be an external cooler or boiler, or may be a heat release to the low temperature part of the system. Incidentally, in each of the above embodiments, a regenerative heat exchanger or a fuel cooler is used. This embodiment makes it possible to control the CO transformer inlet temperature.
[0071]
Note that the control from the first embodiment to the eighth embodiment is not normally performed independently, but the SOFC and the hydrogen utilization device are coordinated by appropriately combining them.
[0072]
Example 9
  Manipulate the distribution ratio of the branching section 32,Thermoelectric ratiochange. According to the present embodiment, the thermoelectric ratio variable operation according to the request from the user becomes possible.
[0073]
Example 10
The ejector drive gas flow rate (# 3or # 4or # 5or # 6) is switched according to the operation mode such as temperature increase, temperature decrease, or power generation. According to the present embodiment, it is possible to select an optimum (highly efficient) driving gas composition according to the operation mode.
[0074]
Example 11
  In a system using a gas turbine as a hydrogen utilization device, the turbine inlet air temperature is adjusted by combustion gas from exhaust fuel and exhaust air. In this case, the supply amount of exhaust fuel and exhaust air is the thermoelectric ratio.CommandAs a preceding signal. According to this embodiment, the turbine inlet temperature can be controlled.
[0075]
Note that the heat recovery device referred to in the claims corresponds to various heat exchangers, exhaust heat recovery devices, and the like in the embodiments.
[0076]
【The invention's effect】
As described above, according to the present invention, there is provided a hydrogen utilization system using a solid oxide fuel cell that has a high fuel utilization rate and further improves the overall efficiency including power generation efficiency and heat utilization rate. can do. In addition, a control system applicable to the present system enables an operation that complies with the restrictions on the control amount.
[Brief description of the drawings]
FIG. 1 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a first embodiment of the present invention.
FIG. 2 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a second embodiment of the present invention.
FIG. 3 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a third embodiment of the present invention.
FIG. 4 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a fourth embodiment of the present invention.
FIG. 5 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a fifth embodiment of the present invention.
FIG. 6 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a sixth embodiment of the present invention.
FIG. 7 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a seventh embodiment of the present invention.
FIG. 8 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to an eighth embodiment of the present invention.
FIG. 9 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a ninth embodiment of the present invention.
FIG. 10 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a tenth embodiment of the present invention.
FIG. 11 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to an eleventh embodiment of the present invention.
FIG. 12 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a twelfth embodiment of the present invention.
FIG. 13 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a thirteenth embodiment of the present invention.
FIG. 14 is a system diagram of a hydrogen utilization system using a solid oxide fuel cell according to a fourteenth embodiment of the present invention.
FIG. 15 is a system diagram of a heat supply increase operation system added to a hydrogen utilization system using the solid oxide fuel cell of the present invention.
FIG. 16 is a system diagram of a control system applicable to a hydrogen utilization system using the solid oxide fuel cell of the present invention.
FIG. 17 is a block diagram of the present control system.
[Explanation of symbols]
1 Regenerative heat exchanger
2 Ejector
3 SOFC
4 Fuel cooler
5 CO transformer
6,19 Condenser
7 Gas recirculation fan
8 Hydrogen utilization equipment
9 Pushing fan
10 Hot air preheater
11, 13 Chimney
12, 14 Waste heat recovery equipment
15 Heat exchanger
16 Gas recirculation fan
17 Waste heat recovery equipment
18 Temperature controller
20 Combustor
21 Waste heat recovery equipment
22 Chimney
31-37 Branch
41, 42 mixing section

Claims (16)

A solid oxide fuel cell that generates power using the fuel while reforming the fuel into a gas containing hydrogen and carbon monoxide;
A CO converter that discharges hydrogen by reacting carbon monoxide contained in the exhausted fuel from the solid oxide fuel cell with water , and the exhausted fuel from the solid oxide fuel cell as the solid oxide fuel A system having a first recirculation system that recirculates to the battery, and a second recirculation system that recirculates gas discharged from the CO converter to the solid oxide fuel cell ;
And hydrogen contained in the exhaust fuel from said solid oxide fuel cell, characterized by comprising a hydrogen utilization device that performs an action using hydrogen, the discharged from the CO transformer, the solid oxide Hydrogen utilization system using physical fuel cells.   A recirculation fan provided between the CO transformer and the second recirculation system to increase the pressure of the gas flowing through the second recirculation system;
  An ejector for connecting the second recirculation system and the first recirculation system,
  The exhaust fuel flowing through the first recirculation system flows into the ejector due to the negative pressure generated in the ejector by the gas flowing through the second recirculation system, and the exhaust fuel flowing through the first recirculation system and the 2. The solid oxide fuel cell according to claim 1, wherein the gas flowing through the second recirculation system merges through the ejector and is supplied to the solid oxide fuel cell. Hydrogen utilization system.   At least one of the gas discharged from the CO converter, the gas discharged from the hydrogen utilization device, and the exhaust fuel and exhaust air from the solid oxide fuel cell is partially branched and mixed with the other. At least one of a gas discharged from a combustor to be burned and exhaust air discharged from the solid oxide fuel cell flows through the second recirculation system and flows into the ejector;
  The solid oxide according to claim 2, wherein the flow rate of the gas supplied to the solid oxide fuel cell is switched by switching the flow rate of the gas flowing through the second recirculation system. Using hydrogen fuel cell. A heat exchanger for exchanging heat between the gas flowing through the second recirculation system and the exhaust fuel discharged from the solid oxide fuel cell;
  4. The solid oxidation according to claim 2, wherein the fuel supplied to the solid oxide fuel cell is supplied from a front stage of the heat exchanger of the second recirculation system. 5. Hydrogen utilization system using physical fuel cells. 5. The solid according to claim 2, wherein the fuel supplied to the solid oxide fuel cell is supplied from a front stage of the ejector of the first recirculation system. Hydrogen utilization system using an oxide fuel cell. The hydrogen using the solid oxide fuel cell according to any one of claims 1 to 5, further comprising a heat recovery device that recovers exhaust heat generated in the solid oxide fuel cell. Usage system. The hydrogen utilization system using a solid oxide fuel cell according to any one of claims 1 to 6, further comprising a heat recovery device that recovers exhaust heat generated in the CO converter. Wherein at least one of the exhaust fuel and exhaust air from the solid oxide fuel cell is branched part, any of claims 1 to 7, characterized in that it comprises a combustor for mixing with the other combustion A hydrogen utilization system using a solid oxide fuel cell according to claim 1. The hydrogen utilization system using a solid oxide fuel cell according to claim 8, further comprising a heat recovery device that recovers exhaust heat generated in the combustor. The solid oxide fuel cell according to any one of claims 1 to 9 , wherein the hydrogen utilization device is a fuel cell, a hydrogen gas turbine, or a hydrogen storage device that generates electricity using hydrogen as fuel. The hydrogen utilization system used. Fuel side inlet temperature and air side inlet temperature in the solid oxide fuel cell, inlet fuel side, air side pressure difference, and fuel side inlet temperature and air side inlet temperature in the hydrogen utilization device for generating power , and Feedforward control is performed to control the state quantities of the inlet fuel side and the air side pressure difference in coordination with each other.
A thermoelectric ratio command, which is a command for setting a thermoelectric ratio, which is a ratio of a calorific value of the hydrogen utilization system and a power generation amount of the solid oxide fuel cell and the hydrogen utilization device, to a desired value is the feedforward. The solid oxide fuel according to any one of claims 1 to 10, wherein control is performed by determining a target value for each control amount of the state amount as a control preceding signal. Hydrogen utilization system using batteries. Fuel side inlet temperature and air side inlet temperature in the solid oxide fuel cell, inlet fuel side, air side pressure difference, and fuel side inlet temperature and air side inlet temperature in the hydrogen utilization device for generating power, and inlet fuel side, air side pressure difference, performs the CO transformer inlet temperature, and the combustor outlet temperature, the state quantity of the feed-forward control in order to control that coordinates each,
A thermoelectric ratio command, which is a command for setting a thermoelectric ratio, which is a ratio of a calorific value of the hydrogen utilization system and a power generation amount of the solid oxide fuel cell and the hydrogen utilization device, to a desired value is the feedforward. 10. The solid oxide fuel cell according to claim 8, wherein the control is performed by determining each target value in each control amount of the state quantity using the control preceding signal. 10. Hydrogen using system. Wherein the exhaust fuel from the solid oxide fuel cell by operating the distribution ratio of the branching portion that branches to the CO transformer and the combustor, to claim 12, characterized in that it has to change the thermoelectric ratio The hydrogen utilization system using the solid oxide fuel cell as described.   The hydrogen utilization system using a solid oxide fuel cell according to claim 12 or 13, wherein the hydrogen utilization device is a fuel cell or a hydrogen gas turbine that generates electricity using hydrogen as fuel. The hydrogen utilization device is a hydrogen gas turbine ;
In order to coordinately control the state quantities of the fuel side inlet temperature, the air side inlet temperature, the inlet fuel side, the air side pressure difference, and the turbine inlet temperature in the solid oxide fuel cell , a feedforward is performed. Control
A thermoelectric ratio command, which is a command for setting a thermoelectric ratio, which is a ratio of a calorific value of the hydrogen utilization system and a power generation amount of the solid oxide fuel cell and the hydrogen utilization device, to a desired value is the feedforward. The solid oxide according to any one of claims 1 to 9, wherein the control is performed by determining each target value in each control amount of the state quantity as a control preceding signal . Using hydrogen fuel cell. The hydrogen utilization device is a hydrogen gas turbine;
Fuel-side inlet temperature of the solid oxide fuel cell, and air-side inlet temperature, and the inlet fuel side, air side pressure difference, cooperative turbine inlet temperature, and the combustor outlet temperature, the, respectively that of the amount of state Feed forward control to control
A thermoelectric ratio command, which is a command for setting a thermoelectric ratio, which is a ratio of a calorific value of the hydrogen utilization system and a power generation amount of the solid oxide fuel cell and the hydrogen utilization device, to a desired value is the feedforward. 10. The solid oxide fuel cell according to claim 8 , wherein a target value in each control amount of the state quantity is determined and controlled as a control preceding signal . 10. Hydrogen utilization system.

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