JP5550327B2 - Solid oxide fuel cell power generation system - Google Patents

Description

  The present invention relates to a solid oxide fuel cell power generation system, and more particularly to utilization of air in a solid oxide fuel cell.

  A solid oxide fuel cell (SOFC) supplies a fuel gas to a fuel electrode, an oxidant gas to an air electrode, and a fuel contained in the fuel gas and an oxygen contained in the oxidant gas. Is generated by a chemical reaction via a solid electrolyte body. In general, natural gas, LPG, petroleum, methanol, coal gasification gas, or the like is used as the fuel gas, and air is used as the oxidant gas.

  In this solid oxide fuel cell, self-heating by power generation may be used as temperature control for maintaining the efficiency of power generation. This self-heating is generated by Joule heat of a cell having a fuel electrode and an air electrode during power generation of the solid oxide fuel cell, and the cell has high conductivity during steady operation of the solid oxide fuel cell. Is used to maintain the temperature range.

  On the other hand, if the cell is overheated by self-heating, the allowable temperature range of the cell may be exceeded. Therefore, the air supplied to the air electrode is also used as a refrigerant for maintaining the solid oxide fuel cell at an appropriate operating temperature. At this time, the air needs an air amount necessary for power generation and an air amount necessary for cooling.

  However, when air is used for cooling the heat generated by power generation, the amount of air required for cooling is generally larger than the amount of air required for power generation (more precisely, the amount of oxygen in the air). Therefore, when the amount of air necessary for cooling increases, the ratio of the amount of air used for power generation to the total amount of air led to the solid oxide fuel cell (hereinafter referred to as “air utilization rate”) decreases. As a result, there is a problem that the efficiency of the entire solid oxide fuel cell power generation system is lowered because the air utilization rate is lowered.

  Patent Document 1 discloses a molten carbonate fuel cell as an example of reducing the amount of air necessary as a refrigerant in a fuel cell that operates at a high temperature. This molten carbonate fuel cell has a plurality of molten carbonate fuel cells installed in series and connected in series, and a cathode gas that connects the cathode outlet of the upstream fuel cell and the cathode inlet of the downstream fuel cell. A heat exchanger is installed in the middle of the line.

  Patent Document 2 discloses that a solid oxide fuel cell is connected in series to an air flow, and air and heat derived from the solid oxide fuel cell are connected to a downstream solid oxide fuel cell. It is disclosed to lead to.

Japanese Patent Laid-Open No. 4-12463 Japanese Patent No. 3349273

  According to the fuel cells disclosed in Patent Document 1 and Patent Document 2 described above, the amount of air supplied for cooling can be reduced by connecting the fuel cells in series with the air flow. However, since a difference occurs in the oxygen concentration in the air introduced into each fuel cell, an output difference occurs between the fuel cells, resulting in a difference in heat generation.

  In this way, when a temperature difference occurs between the solid oxide fuel cells due to the difference in the calorific value, there is a possibility of damaging the elements in the solid oxide fuel cell. There was a problem that operation management of the battery system became difficult.

  The present invention has been made in view of such circumstances, and improves the air utilization rate and optimizes the amount of air and the amount of fuel led to a plurality of solid oxide fuel cells. To provide a solid oxide fuel cell power generation system capable of improving the efficiency of the entire system by reducing the output difference between solid oxide fuel cells and facilitating the operation management of the system. With the goal.

In order to solve the above problems, the solid oxide fuel cell power generation system of the present invention employs the following means.
That is, according to the solid oxide fuel cell power generation system of the present invention, a plurality of solid oxide fuel cells are arranged in series with respect to the air flow and the fuel flow, and the air is upstream of the air flow. The solid oxide fuel cell on the side is supplied to the solid oxide fuel cell on the downstream side with respect to the air flow, and the fuel is supplied to the solid oxide fuel cell on the downstream side with respect to the air flow. To the solid oxide fuel cell upstream of the air flow.

Solid oxide fuel cells arranged in series with respect to the air flow include a solid oxide fuel cell upstream of the air flow and a solid oxide fuel cell downstream of the air flow. A difference occurs in the supplied oxygen concentration. Therefore, when the amount of fuel supplied to each solid oxide fuel cell is the same amount, an output difference is generated in each solid oxide fuel cell, and a difference is generated in the amount of heat generated by power generation. Due to the difference in the amount of heat, a temperature difference occurs between the solid oxide fuel cells, making it difficult to manage the operation of the solid oxide fuel cell power generation system.
In the present invention, a plurality of solid oxide fuel cells are arranged in series with respect to the direction in which air passes, and from the solid oxide fuel cell upstream of the air flow to the downstream of the air flow. Air was supplied to the solid oxide fuel cell. Furthermore, a plurality of solid oxide fuel cells are arranged in series with respect to the direction in which the fuel passes, and a solid oxide upstream of the air flow from the solid oxide fuel cell downstream of the air flow. Fuel was supplied to the fuel cell. Accordingly, the solid oxide fuel cell on the downstream side with respect to the air flow having a low oxygen concentration is supplied with a fuel having a high fuel concentration, and the upstream side with respect to the air flow having a high oxygen concentration to be supplied The solid oxide fuel cell can be supplied with a fuel having a low fuel concentration. Therefore, the output balance between the solid oxide fuel cells can be achieved, and the temperature difference between the solid oxide fuel cells can be suppressed. Therefore, it becomes possible to facilitate the operation management of the solid oxide fuel cell power generation system.

  In addition, by leveling the output between the solid oxide fuel cells, the temperature difference between the cells in the solid oxide fuel cells can also be suppressed, so overheating even when cells are integrated. In addition, the reliability in the cell can be improved, and the durability of the solid oxide fuel cell power generation system in the long-term operation can be improved.

According to the solid oxide fuel cell power generation system according to the reference example of the present invention, the air that is provided between the air flows and has passed through the solid oxide fuel cell upstream of the air flows; A heat exchanger for exchanging heat with the air supplied to the solid oxide fuel cell upstream of the air flow is provided.

When a solid oxide fuel cell generates electricity with air and fuel, heat is generated. In order to cool the generated heat, air is introduced into the solid oxide fuel cell.
In the reference example of the present invention, a heat exchanger is provided between the air flows of the solid oxide fuel cell. As a result, the heat supplied between the air supplied to the solid oxide fuel cell upstream of the air flow and the increased temperature passing through the solid oxide fuel cell upstream of the air flow is exchanged. Is done. Therefore, it is possible to cool the air whose temperature is derived from the solid oxide fuel cell air upstream of the air flow. Therefore, it is possible to secure the amount of air necessary for cooling and improve the efficiency of the entire solid oxide fuel cell power generation system.

According to the solid oxide fuel cell power generation system according to the present invention, air that is provided between the air flows and that has passed through the solid oxide fuel cell on the upstream side with respect to the air flows is guided , the supplied raw fuel characterized in that it comprises a reformer for reforming into fuel to be supplied to the solid oxide fuel cell.

  In the reformer, the fuel supplied by the endothermic reaction is reformed into a reformed fuel. Therefore, the air whose temperature has risen through the solid oxide fuel cell upstream of the air flow is guided to the reformer. Therefore, the fuel can be reformed into a reformed fuel using the heat of the air that has passed through the upstream solid oxide fuel cell. Therefore, the efficiency of the entire solid oxide fuel cell power generation system can be increased.

According to the solid oxide fuel cell power generation system according to the reference example of the present invention, the air that is provided between the air flows and has passed through the solid oxide fuel cell upstream of the air flows; It comprises an economizer that exchanges heat with water.

  The air whose temperature has risen after passing through the solid oxide fuel cell upstream of the air flow is guided to the economizer. Therefore, the water supplied to the economizer exchanges heat with the heat of the air whose temperature has passed through the solid oxide fuel cell on the upstream side with respect to the air flow, and becomes steam. Therefore, the air that has passed through the solid oxide fuel cell can be effectively used as a heat source.

According to the solid oxide fuel cell power generation system according to the present invention, it includes an oxygen supply means, for supplying to the downstream side with respect to air flow of the reformer according oxygen generated by the oxygen supply means on SL It is characterized by that. Further, according to the solid oxide fuel cell power generation system according to the reference example of the present invention, the oxygen supply means is provided, and the oxygen generated by the oxygen supply means is converted into the heat exchanger described above or the economizer described above. It supplies to the downstream side with respect to any one of these air flows.

  Oxygen was supplied to the downstream side of the air flow of the heat exchanger, reformer, or economizer by oxygen supply means. Therefore, it is possible to prevent a decrease in oxygen concentration in the air supplied to the solid oxide fuel cell downstream of the air flow. Therefore, it is possible to increase the efficiency of the entire solid oxide fuel cell power generation system by suppressing the output decrease of the solid oxide fuel cell downstream of the air flow.

  According to the solid oxide fuel cell power generation system of the present invention, an additional fuel supply means is provided between the fuel flows.

  The fuel derived from the solid oxide fuel cell downstream of the air flow was additionally supplied by the fuel additional supply means. Therefore, it is possible to prevent a decrease in the concentration of fuel supplied to the solid oxide fuel cell upstream of the air flow. Therefore, it is possible to suppress the output decrease of the solid oxide fuel cell on the upstream side and increase the efficiency of the entire solid oxide fuel cell power generation system.

  According to the above-described invention, the plurality of solid oxide fuel cells are arranged in series with respect to the direction in which air passes, and the solid oxide fuel cells upstream from the air flow are downstream from the air flow. Air was supplied to the solid oxide fuel cell on the side. Furthermore, a plurality of solid oxide fuel cells are arranged in series with respect to the direction in which the fuel passes, and a solid oxide upstream of the air flow from the solid oxide fuel cell downstream of the air flow. Fuel was supplied to the fuel cell. Thus, the solid oxide fuel cell on the downstream side with respect to the air flow having a low oxygen concentration is supplied with the fuel having a high fuel concentration, and the solid oxide fuel on the upstream side with respect to the air flow having a high oxygen concentration The battery can be supplied with a fuel having a low fuel concentration. Therefore, the output balance between the solid oxide fuel cells can be achieved, and the temperature difference between the solid oxide fuel cells can be suppressed. Therefore, operation management of the solid oxide fuel cell power generation system becomes easy. Furthermore, by optimizing the supply amounts of air and fuel, the amount of air to be supplied can be reduced, so that the system efficiency can be improved.

1 is a schematic configuration diagram of a solid oxide fuel cell power generation system having a heat exchanger according to a first reference embodiment of the present invention. It is a schematic block diagram of the 1st modification of the solid oxide fuel cell electric power generation system which concerns on 1st reference embodiment of this invention. It is a schematic block diagram of the 2nd modification of the solid oxide fuel cell electric power generation system which concerns on 1st reference embodiment of this invention. It is a schematic block diagram of the 3rd modification of the solid oxide fuel cell electric power generation system which concerns on 1st reference embodiment of this invention. It is a schematic block diagram of the 4th modification of the solid oxide fuel cell electric power generation system which concerns on 1st reference embodiment of this invention. It is a modification of the solid oxide fuel cell power generation system which has a reformer concerning a 1st embodiment of the present invention. It is a schematic block diagram of the solid oxide fuel cell power generation system which has the economizer which concerns on 2nd reference embodiment of this invention. It is a schematic block diagram of the solid oxide fuel cell power generation system which has an oxygen supply means and fuel additional supply means which concern on 2nd Embodiment of this invention.

Embodiments according to the present invention will be described below with reference to the drawings.
First reference Embodiment
Hereinafter, a first reference embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a schematic configuration diagram of a solid oxide fuel cell power generation system 1.
The solid oxide fuel cell power generation system 1 includes a plurality of solid oxide fuel cells 2 and a heat exchanger 3 that exchanges heat between air and refrigerant introduced into the solid oxide fuel cells 2. Yes.

  The solid oxide fuel cell system 1 is a system in which a solid oxide fuel cell 2 that has been integrated in the past is separated into solid oxide fuel cells 2, and in FIG. 1, the system is separated into two. . In FIG. 1, the solid oxide granular fuel cell system 1 has two solid oxide fuel cells 2 arranged in series, but the number of solid oxide fuel cells 2 connected in series is arbitrarily selected. Is possible.

  The solid oxide fuel cell 2 is composed of a plurality of power generation elements (hereinafter referred to as “single cells”) that generate electricity by an electrochemical reaction between a fuel such as hydrogen or carbon monoxide and oxygen in the air. However, the structural unit may be a cartridge unit composed of a plurality of cells (not shown). Further, it may be a submodule unit composed of a plurality of cartridges (not shown). Further, it may be a module unit composed of a plurality of submodules (not shown). For example, two solid oxide fuel cells 2 are provided. Each solid oxide fuel cell 2A, 2B is arranged in series with the introduced air flow. The solid oxide fuel cell (solid oxide fuel cell upstream of the air flow) 2A is more than the solid oxide fuel cell (solid oxide fuel cell downstream of the air flow) 2B. It arrange | positions upstream with respect to an air flow.

  The heat exchanger 3 is provided between the air flows of the solid oxide fuel cells 2A and 2B. In the heat exchanger 3, the air having an increased temperature derived from the solid oxide fuel cell 2 </ b> A is a refrigerant introduced from an air supply pipe (not shown) installed in the solid oxide fuel cell power generation system 1. Exchange heat with some air.

Next, a description will be given air flow of the solid oxide fuel cell power generating system 1 according to the present reference embodiment.
Air is led from the air supply pipe provided in the solid oxide fuel cell power generation system 1 to the heat exchanger 3 through the pipe 20. The air guided to the heat exchanger 3 passes through the heat exchanger 3 and then is led out to the pipe 21. The air led out to the pipe 21 is introduced into the solid oxide fuel cell 2A.

  The oxygen in the air led to the solid oxide fuel cell 2A undergoes an electrochemical reaction with the fuel led to the solid oxide fuel cell 2A through a pipe 30 described later. The solid oxide fuel cell 2A generates electric power by causing an electrochemical reaction between oxygen and fuel in the solid oxide fuel cell 2A. When the solid oxide fuel cell 2A generates power, heat is generated.

  The generated heat is led out from the solid oxide fuel cell 2 </ b> A to the pipe 22 together with the air having a reduced oxygen concentration. The heat led out to the pipe 22 and the air with reduced oxygen concentration (hereinafter referred to as “exhaust air”) are led to the heat exchanger 3. The exhausted air guided to the heat exchanger 3 exchanges heat with the air guided to the heat exchanger 3 by the pipe 20 described above. The temperature of the exhausted air heat-exchanged in the heat exchanger 3 is lowered. The exhaust air whose temperature has been lowered by heat exchange is led out from the heat exchanger 3 to the pipe 23. The temperature of the exhaust air led out to the pipe 23 is set to a temperature suitable for performing an electrochemical reaction in the solid oxide fuel cell 2B described later.

  On the other hand, heat is given to the air guided from the pipe 20 to the heat exchanger 3 by exchanging heat with the exhaust air. The air whose temperature has been increased by the application of heat has a temperature suitable for the electrochemical reaction and is led to the solid oxide fuel cell 2A.

  The exhaust air led out to the pipe 23 is led to the solid oxide fuel cell 2B. The residual oxygen in the exhausted air led to the solid oxide fuel cell 2B undergoes an electrochemical reaction with the fuel led to the solid oxide fuel cell 2B through a pipe 31 described later. The solid oxide fuel cell 2B generates electric power by causing an electrochemical reaction between oxygen and fuel in the solid oxide fuel cell 2B.

  The heat generated by the power generation in the solid oxide fuel cell 2B is led out from the solid oxide fuel cell 2B to the pipe 24 together with the air whose oxygen concentration is further reduced. The heat and air led out to the pipe 24 are led to an air discharge pipe (not shown) provided in the solid oxide fuel cell power generation system 1.

Next, a description is given of a fuel flow of the solid oxide fuel cell power generating system 1 according to the present reference embodiment.
Fuel is guided to the solid oxide fuel cell 2B from a pipe 31 connected to a fuel storage tank or the like (not shown) provided in the solid oxide fuel cell power generation system 1. The fuel guided to the solid oxide fuel cell 2B performs an electrochemical reaction with the oxygen in the exhaust air guided by the pipe 23 described above.

  The solid oxide fuel cell 2B generates power by the fuel introduced to the solid oxide fuel cell 2B and oxygen in the exhaust air. After power generation in the solid oxide fuel cell 2B, the fuel whose fuel concentration has decreased (hereinafter referred to as “fuel exhaust gas”) is led out from the solid oxide fuel cell 2B to the pipe 30.

  The fuel exhaust gas led out to the pipe 30 is led to the solid oxide fuel cell 2A. The fuel exhaust gas led to the solid oxide fuel cell 2A performs an electrochemical reaction with oxygen in the air led from the pipe 21 described above. The solid oxide fuel cell 2A generates electric power by causing an electrochemical reaction between oxygen and fuel in the solid oxide fuel cell 2A.

  After power generation in the solid oxide fuel cell 2 </ b> A, the fuel whose fuel concentration has further decreased is led out to the pipe 32. The fuel led out to the pipe 32 is led to a fuel collecting pipe (not shown) provided in the solid oxide fuel cell power generation system 1.

As described above, according to the solid oxide fuel cell power generation system according to this reference embodiment has the following advantages.
Two (plural) solid oxide fuel cells 2A and 2B are arranged in series with respect to the direction in which air passes, and a solid oxide fuel cell (solid oxide fuel cell upstream of the air flow) ) Air was supplied from 2A to the solid oxide fuel cell (solid oxide fuel cell downstream of the air flow) 2B. Furthermore, two solid oxide fuel cells 2A and 2B are arranged in series with respect to the direction in which the fuel passes, and fuel is supplied from the solid oxide fuel cell 2B to the solid oxide fuel cell 2A. did.

  As a result, the fuel having a high fuel concentration is supplied to the solid oxide fuel cell 2B having a low oxygen concentration, and the fuel exhaust gas having a low fuel concentration is supplied to the solid oxide fuel cell 2A having a high oxygen concentration. can do. Therefore, the output balance between the solid oxide fuel cells 2A and 2B can be balanced, and the temperature difference between the solid oxide fuel cells 2A and 2B can be suppressed. Therefore, the operation management of the solid oxide fuel cell power generation system 1 is facilitated.

  Furthermore, the temperature difference between the cells in the solid oxide fuel cells 2A and 2B can be suppressed by leveling the output between the solid oxide fuel cells 2A and 2B. Therefore, even when the cells are integrated, the reliability in the cells can be improved without overheating. Therefore, the durability of the solid oxide fuel cell power generation system 1 in the long-term operation can be improved.

  The heat exchanger 3 is provided between the air flows of the solid oxide fuel cells 2A and 2B. Thereby, in the heat exchanger 3, the air supplied from the pipe 20 via the pipe 21 to the solid oxide fuel cell 2A and the exhaust air whose temperature has passed through the solid oxide fuel cell 2A is heat-exchanged. Is done. Therefore, exhaust air having a high temperature derived from the solid oxide fuel cell 2A can be cooled. Therefore, it is possible to secure an air amount necessary for cooling the exhaust air and to improve the efficiency of the solid oxide fuel cell power generation system 1 as a whole. Moreover, the temperature required for cooling can also be ensured in the air supplied to the solid oxide fuel cell 2B.

In the solid oxide fuel cell power generating system 1 of the present reference embodiment, the solid oxide fuel cell 2A, although during 2B been described as having only the heat exchanger 3, the present invention is not limited thereto Instead of this, the combustor 8 may be provided on the upstream side of the heat exchanger 3. Note that the solid oxide fuel cell power generation system of Modification 1 of the present reference embodiment is different from the first reference embodiment in that it has a combustor 8, and the others are the same. Therefore, the description of the same configuration, air flow, and fuel flow is omitted.
The combustor 8 is provided between the solid oxide fuel cell 2 </ b> A and the exhaust air from the heat exchanger 3, as in Modification 1 shown in FIG. 2.
The first blower 9 compresses the introduced gas and blows it.

The air flow of the solid oxide fuel cell power generation system 1 according to Modification 1 of the reference embodiment will be described.
Exhaust air led out from the solid oxide fuel cell 2 </ b> A to the pipe 22 is led to the combustor 8. Exhaust air guided to the combustor 8 becomes exhaust gas having a high temperature by combustion. The exhaust gas whose temperature has risen is led to the heat exchanger 3. The exhaust air guided to the heat exchanger 3 exchanges heat with the air guided by the pipe 20 and the temperature is lowered. The exhaust gas whose temperature has dropped is led out from the heat exchanger 3 to the pipe 26. The exhaust gas led out to the pipe 26 contains residual oxygen. The exhaust gas derived from the heat exchanger 3 is guided to the solid oxide fuel cell 2B through the pipe 26.

Next, the fuel flow of the solid oxide fuel cell power generation system 1 according to Modification 1 of the reference embodiment will be described.
A part of the fuel exhaust gas derived from the solid oxide fuel cell 2 </ b> A flowing through the pipe 32 is branched and led to the pipe 36. The fuel exhaust gas guided to the pipe 36 is pressurized by the first blower 9 provided on the pipe 36. The fuel exhaust gas pressurized by the first blower 9 is led out to the pipe 37. The fuel exhaust gas led out to the pipe 37 is joined to the pipe 31. The fuel exhaust gas joined to the pipe 31 and the fuel led from the fuel storage tank or the like are led to the solid oxide fuel cell 2B through the pipe 31.

As described above, the solid oxide fuel cell power generation system according to Modification 1 has the following operational effects.
Even if only the heat exchanger 3 cannot heat the air to a temperature for operating the solid oxide fuel cell 2B, the combustor 8 is provided to guide the solid oxide fuel cell 2B. Air can be heated to a predetermined temperature.
The predetermined temperature refers to a temperature for operating the solid oxide fuel cell 2B.

In the present invention, a gas turbine may be provided instead of the heat exchanger.
In this case, the gas turbine 11 is provided between the exhaust air of the solid oxide fuel cell 2A and the solid oxide fuel cell 2B as in Modification 2 shown in FIG. Incidentally, the solid oxide fuel cell power generation system of Modification Example 2 of the present reference embodiment is different from the first reference embodiment in that a gas turbine 11, the others are similar. Therefore, the description of the same configuration, air flow, and fuel flow is omitted.
The gas turbine 11 includes a combustor 11a, a turbine 11b to which exhaust gas discharged from the combustor 11a is guided, a shaft 11c connected to the turbine 11b, and a compressor 11d provided on the shaft 11c. ing.
The first blower 9 compresses the introduced gas and blows it.

Next, the air flow of the solid oxide fuel cell power generation system 1 according to Modification 2 will be described.
The exhaust air led out from the solid oxide fuel cell 2 </ b> A to the pipe 22 is led to the combustor 11 a of the gas turbine 11. The exhaust gas discharged from the combustor 11a after being discharged is guided from the combustor 11a to the turbine 11b. The exhaust gas guided to the turbine 11b rotates the turbine 11b. The shaft 11c is rotationally driven by the turbine 11b being rotationally driven. Since the shaft 11c is rotationally driven, the compressor 11d provided on the coaxial 11c is rotationally driven. Thereby, the compressor 11d compresses air. The air compressed by the compressor 11d is led out to the pipe 21. The compressed air led out to the pipe 21 is led to the solid oxide fuel cell 2A.
Exhaust air containing oxygen that has not been used for combustion in the combustor 11a is led out to the pipe 23 and led to the solid oxide fuel cell 2B.

Next, the fuel flow of the solid oxide fuel cell power generation system 1 according to Modification 2 will be described.
A part of the fuel exhaust gas derived from the solid oxide fuel cell 2 </ b> A flowing through the pipe 32 is branched and led to the pipe 36. The fuel exhaust gas guided to the pipe 36 is pressurized by the first blower 9 provided on the pipe 36. The fuel exhaust gas pressurized by the first blower 9 is led out to the pipe 37. The fuel exhaust gas led out to the pipe 37 is joined to the pipe 31. The fuel exhaust gas joined to the pipe 31 and the fuel led from the fuel storage tank or the like are led to the solid oxide fuel cell 2B through the pipe 31.

As described above, the solid oxide fuel cell power generation system according to Modification 2 has the following operational effects.
The gas turbine 11 having the combustor 11a is provided between the air flows of the solid oxide fuel cells 2A and 2B. Thereby, the gas turbine 11 can supply the compressed air to the solid oxide fuel cell 2A. The exhaust gas derived from the gas turbine 11 contains oxygen that has not been used for combustion. The exhaust gas containing oxygen was led to the solid oxide fuel cell 2B. Thereby, the efficiency of the whole solid oxide fuel cell system 1 can be improved, without installing the apparatus which pressurizes air separately.

Further, in addition to the first blower 9 shown in FIGS. 2 and 3, the fuel exhaust gas derived from the solid oxide fuel cell 2B is boosted as shown in Modification 3 in FIG. 4 and Modification 4 in FIG. The second blower 10 may be additionally provided.
In this case, the fuel exhaust gas derived from the solid oxide fuel cell 2 </ b> B is guided from the pipe 38 to the second blower 10. The fuel exhaust gas guided to the second blower 10 is pressurized by the second blower 10 and led out to the pipe 40. A part of the pressurized fuel exhaust gas led to the pipe 40 is led to the solid oxide fuel cell 2A through the pipe 39.

  In addition, the remainder of the pressurized fuel exhaust gas led to the pipe 40 is joined to the pipe 37. The pressurized fuel exhaust gas joined to the pipe 37 and the fuel exhaust gas led from the solid oxide fuel cell 2 </ b> A flowing through the pipe 37 are joined to the pipe 31. The fuel exhaust gas joined to the pipe 31 is led to the solid oxide fuel cell 2B through the pipe 31 together with the fuel led from the fuel storage tank or the like.

First Embodiment
Hereinafter, a first embodiment of the present invention will be described with reference to FIG. The solid oxide fuel cell power generation system of this embodiment is different from that of the first embodiment in that it has a reformer, and the others are the same. Therefore, the description of the same configuration, air flow, and fuel flow is omitted.
FIG. 6 shows a schematic configuration diagram of a solid oxide fuel cell power generation system 1 including a reformer.

  The reformer 4 performs a steam reforming reaction by reacting raw fuel (fuel) and steam on a catalyst. The reformer 4 reforms the raw fuel into a reformed fuel containing hydrogen as a main component by performing a steam reaction. The reformer 4 is provided between the air flows of the solid oxide fuel cells 2A and 2B.

Next, the air flow of the solid oxide fuel cell power generation system 1 according to this embodiment will be described.
Air is introduced into the solid oxide fuel cell 2 </ b> A from a pipe 25 connected to an air supply pipe (not shown) provided in the solid oxide fuel cell power generation system 1. The oxygen in the air led to the solid oxide fuel cell 2A performs an electrochemical reaction with the reformed fuel led to the solid oxide fuel cell 2A through the pipe 30. In the solid oxide fuel cell 2A, oxygen and the reformed fuel undergo an electrochemical reaction, whereby the solid oxide fuel cell 2A generates electric power.

  The heat generated in the solid oxide fuel cell 2A is guided to the pipe 22 together with the exhaust air. The exhaust air containing the heat guided to the pipe 22 is guided to the reformer 4. The heat in the exhaust air led to the reformer 4 is used for the steam reforming reaction of the raw fuel led to the reformer 4 from a pipe 33 described later.

  The steam reforming reaction in the reformer 4 is an endothermic reaction. Therefore, the heat in the exhaust air led from the pipe 22 to the reformer 4 is used for the steam reforming reaction in the reformer 4.

  Due to the steam reforming reaction in the reformer 4, the temperature of the exhausted air in which heat is used is lowered. The exhaust air whose temperature has been lowered is led out from the reformer 4 to the pipe 23. The exhaust air having a lowered temperature led to the pipe 23 is led to the solid oxide fuel cell 2B. The exhaust air led from the pipe 23 to the solid oxide fuel cell 2B is set to a temperature suitable for performing an electrochemical reaction in the solid oxide fuel cell 2B.

Next, the fuel flow of the solid oxide fuel cell power generation system 1 according to this embodiment will be described.
The raw fuel and water vapor are guided to the reformer 4 by a pipe 33 connected to a fuel storage tank (not shown) provided in the solid oxide fuel cell power generation system 1. The raw fuel guided to the reformer 4 is reformed into reformed fuel containing hydrogen as a main component by exhaust air containing heat guided from the pipe 22 described above.

  The reformed fuel is led out from the reformer 4 to the pipe 34. The reformed fuel led out to the pipe 34 is led to the solid oxide fuel cell 2B. The reformed fuel led to the solid oxide fuel cell 2B performs an electrochemical reaction with the exhaust air led by the pipe 23 described above.

As described above, the solid oxide fuel cell power generation system according to this embodiment has the following operational effects.
The exhaust air whose temperature has risen after passing through the solid oxide fuel cell (solid oxide fuel cell upstream of the air flow) 2A is guided to the reformer 4. Therefore, the raw fuel (fuel) can be reformed into reformed fuel using the heat of the exhaust air that has passed through the solid oxide fuel cell 2A. Accordingly, it is possible to increase the efficiency of the solid oxide fuel cell power generation system 1 as a whole.

Second Reference Embodiment
Hereinafter, a second reference embodiment of the present invention will be described with reference to FIG. The solid oxide fuel cell system of the present embodiment is different from the first embodiment in that it has an economizer, and the others are the same. Therefore, the description of the same configuration, air flow, and fuel flow is omitted.
FIG. 7 shows a schematic configuration diagram of a solid oxide fuel cell power generation system 1 including an economizer 5.

  The economizer 5 uses exhaust heat to heat the water supply. The economizer 5 is provided between the air flows of the solid oxide fuel cells 2A and 2B.

Next, the air flow of the solid oxide fuel cell power generation system 1 according to this embodiment will be described.
Air is introduced into the solid oxide fuel cell 2 </ b> A by a pipe 25 connected to an air supply pipe (not shown) provided in the solid oxide fuel cell power generation system 1. The oxygen in the air led to the solid oxide fuel cell 2A performs an electrochemical reaction with the fuel led to the solid oxide fuel cell 2A through the pipe 30. The solid oxide fuel cell 2A generates electric power by causing an electrochemical reaction between oxygen and fuel in the solid oxide fuel cell 2A. When the solid oxide fuel cell 2A generates power, heat is generated.

The heat generated by the power generation is guided to the pipe 22 together with the exhaust air derived from the solid oxide fuel cell 2A. The exhaust air containing the heat guided to the pipe 22 is guided to the economizer 5. Heat in the exhaust air guided to the economizer 5 is heat-exchanged with water guided to the economizer 5 via a pipe 40 from a water supply pipe (not shown) provided in the solid oxide fuel cell system 1. The The exhaust air heat-exchanged in the economizer 5 gives heat to the water led to the economizer 5 and the temperature is lowered. The exhaust air whose temperature has decreased is led out to the pipe 23.
Further, the water led to the economizer 5 is heated by heat exchange and led out from the pipe 41.

  The exhaust air having a lowered temperature led to the pipe 23 is led to the solid oxide fuel cell 2B. The exhaust air introduced from the pipe 23 to the solid oxide fuel cell 2B is set to a temperature suitable for performing an electrochemical reaction in the solid oxide fuel cell 2B.

Next, the fuel flow of the solid oxide fuel cell power generation system 1 according to this embodiment will be described.
The fuel is led to the solid oxide fuel cell 2B by a pipe 31 connected to a fuel storage tank (not shown) provided in the solid oxide fuel cell power generation system 1. The fuel guided to the solid oxide fuel cell 2B performs an electrochemical reaction with oxygen in the exhaust air guided by the pipe 23 described above.

As described above, the solid oxide fuel cell system according to the present embodiment has the following effects.
The exhaust air whose temperature has risen after passing through the solid oxide fuel cell (solid oxide fuel cell upstream of the air flow) 2 </ b> A is guided to the economizer 5. Therefore, the water supplied to the economizer 5 is heated by exchanging heat with the heat of exhaust air whose temperature has passed through the solid oxide fuel cell 2A. Therefore, the exhaust air that has passed through the solid oxide fuel cell 2A can be effectively used as a heat source.

[ Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. The solid oxide fuel cell power generation system of this embodiment is different from the first embodiment in that it has an oxygen supply means and an additional fuel supply means, and the others are the same. Therefore, the description of the same configuration, air flow, and fuel flow is omitted.
FIG. 8 shows a schematic configuration diagram of a solid oxide fuel cell power generation system 1 including an oxygen supply means 6 and an additional fuel supply means 7.
The oxygen supply means 6 supplies oxygen.
The additional fuel supply means 7 supplies additional fuel.

Next, the air flow of the solid oxide fuel cell power generation system 1 according to this embodiment will be described.
The heat is exchanged in the heat exchanger 3, the temperature is lowered, and the exhaust air is led out to the pipe 23. The exhaust air led out to the pipe 23 has a reduced oxygen concentration. Therefore, oxygen is supplied into the pipe 23 by the oxygen supply means 6. Thereby, the oxygen concentration in the exhausted air led to the solid oxide fuel cell 2B can be made the same as the oxygen concentration in the air led to the solid oxide fuel cell 2A.

Next, the fuel flow of the solid oxide fuel cell power generation system 1 according to this embodiment will be described.
The fuel exhaust gas led out from the solid oxide fuel cell 2B to the pipe 30 has a reduced fuel concentration. Therefore, the fuel is supplied into the pipe 30 by the additional fuel supply means 7. Thereby, the fuel concentration led to the solid oxide fuel cell 2A and the fuel concentration led to the solid oxide fuel cell 2B can be made the same.

As described above, the solid oxide fuel cell power generation system according to this embodiment has the following operational effects.
Oxygen is supplied from the oxygen supply means 6 to the exhaust air flowing through the pipe 23 on the downstream side of the heat exchanger 3. Therefore, the output of the solid oxide fuel cell 2B is reduced by preventing a decrease in the oxygen concentration in the exhaust air supplied to the solid oxide fuel cell (solid oxide fuel cell downstream of the air flow) 2B. Can be suppressed. Accordingly, it is possible to increase the efficiency of the solid oxide fuel cell power generation system 1 as a whole.

  The fuel exhaust gas derived from the solid oxide fuel cell 2 </ b> B is supplied with fuel by the fuel additional supply means 7. Therefore, a decrease in the concentration of the fuel exhaust gas supplied to the solid oxide fuel cell (solid oxide fuel cell upstream of the air flow) 2A is prevented to reduce the output of the solid oxide fuel cell 2A. Can be suppressed. Accordingly, it is possible to increase the efficiency of the solid oxide fuel cell power generation system 1 as a whole.

  In this embodiment, although demonstrated using the heat exchanger 3, this invention is not limited to this, A reformer, an economizer, etc. may be sufficient.

DESCRIPTION OF SYMBOLS 1 Solid oxide fuel cell power generation system 2 Solid oxide fuel cell 2A Solid oxide fuel cell upstream of air flow (solid oxide fuel cell)
2B Solid oxide fuel cell downstream of the air flow (solid oxide fuel cell)

Claims (3)

Arranging a plurality of solid oxide fuel cells in series with the air stream and the fuel stream;
Air is supplied from the solid oxide fuel cell upstream of the air flow to the solid oxide fuel cell downstream of the air flow;
Fuel is supplied from the solid oxide fuel cell downstream of the air flow to the solid oxide fuel cell upstream of the air flow;
Air that is provided between the air flows and that has passed through the solid oxide fuel cell on the upstream side with respect to the air flow is guided, and the supplied raw fuel is supplied to the solid oxide fuel cell. A solid oxide fuel cell power generation system including a reformer that reforms into a solid fuel. With oxygen supply means, a solid oxide fuel cell power generation system according to claim 1 to be supplied to the downstream side of the oxygen generated by the oxygen supply means to the air flow before Kiaratameshitsu device. Wherein between the fuel flow, the solid oxide fuel cell power generation system according to claim 1 or 2 comprising a fuel supply additional means.

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