JP6783094B2 - Fuel cell control device, fuel cell protection control method, and power generation system - Google Patents

Description

The present invention relates to a fuel cell control device, a fuel cell protection control method, and a power generation system.

A fuel cell is a power generation device that uses a power generation method based on an electrochemical reaction. It has a fuel electrode, which is an electrode on the fuel side, an air electrode, which is an electrode on the air (oxidizing agent gas) side, and only ions between them. It is composed of an electrolyte that allows it to pass through, and various types have been developed depending on the shape of the battery and the constituent materials.

Of these, for example, solid oxide fuel cells (Solid Oxide Fuel Cell: hereinafter referred to as "SOFC") use ceramics such as zirconia ceramics as an electrolyte, and carbonaceous raw materials are converted into coal gas produced by a gasification facility. It is a fuel cell operated by using gas such as gas, hydrogen, city gas, natural gas, oil, methanol, etc. as fuel. This SOFC has a high operating temperature of about 700 to 1000 ° C. in order to increase ionic conductivity, and is known as a highly efficient high-temperature fuel cell.

A combined cycle system has been developed in which such an SOFC is combined with an internal combustion engine such as a micro gas turbine (hereinafter referred to as "MGT"). In the MGT, the compressed air discharged from the compressor is supplied to the air electrode of the SOFC, and the high-temperature exhaust fuel gas discharged from the SOFC is supplied to the combustor of the MGT for combustion, and the combustion gas generated in the combustor is used. The MGT turbine is driven to rotate by adiabatic expansion. Then, by transmitting the rotational drive of the turbine to the generator to generate electricity, it is possible to generate electricity with high power generation efficiency.

Such SOFCs are designed to make an emergency stop from the viewpoint of making it safer when some abnormality such as a large drop in cell voltage or a rapid temperature rise in a power generation cell is detected. For example, Patent Document 1 discloses that when an abnormality requiring the stop of SOFC occurs, an appropriate stop operation is performed according to an operating state (for example, blower operation and whether or not an inert gas can be supplied). ing.
Further, for example, Patent Document 2 discloses a system in which, when an abnormality is detected, SOFC is automatically restarted according to a risk level after power generation is stopped, and power generation is restarted.
Further, Patent Document 3 discloses that it is determined whether or not to stop the operation of the SOFC based on the SOFC output and the voltage drop amount of the fuel cell module.

Japanese Unexamined Patent Publication No. 2014-146476 Japanese Patent No. 5112107 Japanese Patent No. 4924910

In the conventional SOFC, when an abnormality is detected, the operation of the SOFC is stopped and cooled regardless of the cause of the abnormality, so it takes a considerable amount of time to restart the SOFC and restart the power generation. Was. That is, SOFC requires a temperature raising step of raising the temperature of the power generation chamber to a temperature at which power generation is possible at the time of starting, and it is necessary to start power generation after the temperature of the power generation chamber reaches a temperature at which power generation is possible. The longer the elapsed time from the operation stop due to the occurrence of an abnormality, the lower the temperature of the power generation room, and therefore the longer the time required for the temperature raising process. In particular, when restarting from a cold start after the temperature of the power generation chamber has been cooled to a room temperature level, it may take one day or more to complete the start-up.

The present invention has been made in view of such circumstances, and even when an abnormality occurs, the power generation output of the fuel cell is reduced, the time for stopping the operation is shortened, and the power generation output of the fuel cell is increased. It is an object of the present invention to provide a fuel cell control device, a fuel cell protection control method, and a power generation system that can be used.

The present invention is a fuel cell control device including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged, and the fuel cell incorporated in the control device. Based on the plurality of measurement data, the abnormality determination unit determines whether or not a specific abnormality that may be resolved by increasing or decreasing the load of the fuel cell has occurred, and the abnormality determination unit identifies the abnormality. When it is determined that the abnormality has occurred, the output control unit that reduces or increases the load of the fuel cell and the load of the fuel cell are reduced or increased according to the cause of the specific abnormality that has occurred. As a result, an abnormality resolution determination unit that determines whether or not the specific abnormality has been resolved, a storage unit that stores cause identification information that associates information on the specific abnormality with the cause of the specific abnormality, and the above-mentioned storage unit. When the abnormality determination unit determines that the specific abnormality has occurred, the extraction unit that extracts the cause identification information corresponding to the specific abnormality that has occurred from the storage unit, and the extraction unit that is extracted by the extraction unit. Provided is a fuel cell control device including a cause identification unit for identifying the cause of causing the specific abnormality by using the cause identification information .

In the fuel cell control device, the "specific abnormality" is, for example, an abnormality relating to an increase or decrease in the temperature of the power generation chamber.
In the fuel cell control device, the "fuel cell load" is the power generation output of the fuel cell.
In the fuel cell control device, the output control unit controls to maintain the load when the specific abnormality is resolved when the abnormality resolution determination unit determines that the specific abnormality has been resolved. You may do it.

According to the fuel cell control device, the output control unit reduces or increases the load when the abnormality determination unit determines that a specific abnormality has occurred. Here, since the "specific abnormality" is an abnormality that may be resolved by increasing or decreasing the load, the abnormality may be resolved by reducing or increasing the load. Then, when the abnormality is resolved, the operation is continued with the load at the time when the abnormality is resolved. Therefore, the conventional power generation system that stops the operation when the abnormality occurs regardless of the cause of the abnormality. It is possible to increase the amount of power generated.
According to the fuel cell control device, the cause of the specific abnormality that has occurred is identified by using the cause identification information that associates the information about the specific abnormality with the cause of the specific abnormality. The time required can be shortened, and the labor required to clarify the cause can be reduced.

In the fuel cell control device, the abnormality resolution determination unit holds the load of the fuel cell after the decrease or increase for a predetermined period of time, which is set in advance by reducing or increasing the load of the fuel cell by the output control unit. After that, it may be determined whether or not the specific abnormality has been resolved.

For example, since the power generation room temperature has a large heat capacity, a change in the power generation room temperature has a delay in responding to a load change. According to the fuel cell control device, it is determined whether or not a specific abnormality has been resolved after the load of the fuel cell after the decrease or increase is held for a preset predetermined period, so that the load after the change can be determined. On the other hand, it is possible to reliably determine whether or not the abnormality has been resolved.

In the fuel cell control device, the output control unit limits the target load to a predetermined protection lower limit value or a predetermined protection upper limit value until the abnormality resolution determination unit determines that the specific abnormality has been resolved. , The target load may be gradually decreased or increased by a predetermined amount.

According to the fuel cell control device, the target load can be gradually lowered or increased to a predetermined protection lower limit value or a predetermined protection upper limit value while confirming whether or not the abnormality has been resolved. .. As a result, if the abnormality is resolved while changing the load to the protection lower limit value or protection upper limit value, the load at the time when the abnormality is resolved can be maintained, and the target load can be increased to the protection lower limit value at once. It is possible to maintain a higher output than when it is lowered or raised to the upper limit of protection.
The above-mentioned "gradual decrease or increase of the target load" means, for example, repeating an operation of decreasing or increasing the target load by a predetermined amount, holding the state for a predetermined period, and then further decreasing or increasing the load by a predetermined amount. Means that.
Further, the above-mentioned "predetermined amount" when changing the target load is set to a value larger than the load change width that causes a change in the temperature of the power generation chamber.

In the fuel cell control device, the output control unit lowers or raises the target load to a predetermined protection lower limit value or a predetermined protection upper limit value, and the abnormality elimination determination unit indicates that the target load is the protection lower limit value or After reaching the protection upper limit value and holding the predetermined period, it may be determined whether or not the specific abnormality has been resolved.

Among the specific abnormalities, there are some factors that cannot be expected to be resolved even if the load is changed stepwise as described above. In the case of the cause of such an abnormality, it is determined whether or not the specific abnormality has been resolved after the target load is continuously changed to the protection lower limit value or the protection upper limit value at once. In this way, depending on the cause of the load, by omitting the process of gradually changing the load to the predetermined protection lower limit value or protection upper limit value, it is confirmed in a shorter time whether or not the abnormality can be resolved by the load change. It becomes possible to do.

In the fuel cell control device, the protection lower limit value is set to, for example, a value larger than the load of the fuel cell in which the supply of reforming water is required.

Aqueduct for reforming is required to reform the fuel gas supplied to the fuel cell. The exhaust fuel gas discharged from the fuel cell is recirculated to the fuel cell, but since the flow rate of water vapor contained in the exhaust fuel gas differs depending on the operating condition of the fuel cell, it becomes the exhaust fuel gas depending on the operating condition of the fuel cell. The water for reforming may be insufficient only with the contained water vapor. In addition, at the start of supply of reforming water, some disturbances such as pressure fluctuations and flow fluctuations occur. By setting the lower limit of protection to a value larger than the load that requires the supply of reforming water, abnormalities will occur in a stable state without being affected by pressure fluctuations and flow fluctuations due to the supply of reforming water. It is possible to determine whether or not the problem has been resolved.

In the fuel cell control device, the output control unit controls to recover the load of the fuel cell to the required load when it is determined that the specific abnormality is resolved and the specific abnormality does not recur. You may do it.

According to the fuel cell control device, when it is determined that the specific abnormality is resolved and the specific abnormality does not recur, the load is from the currently maintained load to a predetermined load (for example, rated load). Therefore, for example, the time required for load recovery can be shortened as compared with the case of recovering from a state where the load is zero to a predetermined load.

The fuel cell control device may further include a display unit that displays the cause identified by the cause identification unit.

According to the fuel cell control device, it is possible to notify the operator of the cause of the abnormality by displaying the cause of the abnormality on the display unit. As a result, the operator can confirm the cause and take appropriate measures for the abnormality that has occurred promptly without having to clarify the abnormality by himself / herself.

The fuel cell control device may further include a cause elimination unit that eliminates the cause identified by the cause identification unit.

According to the fuel cell control device, it is possible to automatically eliminate the cause of the abnormalities that have occurred. This makes it possible to automatically recover the load.

The present invention comprises a micro gas turbine, a fuel cell including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged, and a control device for any of the above fuel cells. Provide a power generation system to be equipped.

The present invention is a protection control method for a fuel cell including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged, and can be applied to a plurality of measurement data related to the fuel cell. Based on this, a step of determining whether or not a specific abnormality that may be resolved by increasing or decreasing the load of the fuel cell has occurred, and a step that occurs when it is determined that the specific abnormality has occurred. A step of increasing or decreasing the load of the fuel cell according to the cause of the specific abnormality, and a step of determining whether or not the specific abnormality has been resolved by increasing or decreasing the load of the fuel cell. And the step of storing the cause identification information in which the information about the specific abnormality is associated with the cause of the specific abnormality, and when it is determined that the specific abnormality has occurred, it is generated from the cause identification information. A fuel cell protection control method including a step of extracting the cause identification information corresponding to the specific abnormality and a step of identifying the cause causing the specific abnormality by using the extracted cause identification information. provide.

The fuel cell protection control method may further include a step of maintaining the load of the fuel cell when the specific abnormality is resolved when it is determined that the specific abnormality has been resolved.

According to the present invention, even if an abnormality occurs in a fuel cell or a power generation system including a fuel cell, the power generation output of the fuel cell can be reduced or the time for stopping operation can be shortened to increase the power generation output of the fuel cell. It has the effect of being able to.

It is a schematic block diagram which showed the schematic structure of the power generation system which concerns on one Embodiment of this invention. It is a figure which showed one aspect of the cell stack of SOFC which concerns on one Embodiment of this invention. It is a figure which showed one aspect of the SOFC module which concerns on one Embodiment of this invention. It is sectional drawing of one aspect of the SOFC cartridge which concerns on one Embodiment of this invention. It is a functional block diagram which expanded and showed the function related to protection control among the functions provided in the SOFC control device which concerns on 1st Embodiment of this invention. It is a flowchart which showed the procedure of protection control executed by the control device of SOFC which concerns on 1st Embodiment of this invention. It is a figure which showed an example of the temporal transition of the output current command when a specific abnormality occurs in the SOFC control apparatus which concerns on 1st Embodiment of this invention. It is a functional block diagram which expanded and showed the function related to protection control among the functions provided in the SOFC control device which concerns on 2nd Embodiment of this invention. It is a figure which showed the schematic structure of the abnormality cause identification part which concerns on 2nd Embodiment of this invention. It is a flowchart which showed the procedure of the abnormality cause identification control executed by the control device of SOFC which concerns on 2nd Embodiment of this invention.

[Power generation system configuration]
First, a schematic configuration of a power generation system according to an embodiment of the present invention will be described.
FIG. 1 is a schematic configuration diagram showing a schematic configuration of a power generation system 10 according to an embodiment of the present invention. As shown in FIG. 1, the power generation system 10 includes a micro gas turbine (hereinafter referred to as “MGT”) 11, a generator 12, and SOFC 13. The power generation system 10 is configured to obtain high power generation efficiency by combining power generation by the MGT 11 and power generation by the SOFC 13.

The MGT 11 has a compressor 21, a combustor 22, and a turbine 23, and the compressor 21 and the turbine 23 are integrally rotatably connected by a rotating shaft 24. The compressor 21 is rotationally driven by the rotation of the turbine 23, which will be described later. The compressor 21 compresses the air A taken in from the air take-in line 25.
A part of compressed air (hereinafter, simply referred to as “air”) A from the compressor 21 is supplied to the combustor 22 via the first air supply line 26, and the first fuel gas supply line 27 is provided. The fuel gas L1 is supplied through the fuel gas L1. The first air supply line 26 is provided with a control valve 65 for adjusting the amount of air supplied to the combustor 22, and the first fuel gas supply line 27 adjusts the flow rate of fuel gas supplied to the combustor 22. A control valve 70 is provided for this purpose. Further, a part of the exhaust fuel gas L3 circulating in the fuel gas recirculation line 49 of the SOFC 13 described later is supplied to the combustor 22 through the exhaust fuel gas supply line 45. The exhaust fuel gas supply line 45 is provided with a control valve 47 for adjusting the amount of exhaust fuel gas supplied to the combustor 22. Further, a part of the exhaust air A2 used in the air electrode 13B of the SOFC 13 is supplied to the combustor 22 through the exhaust air supply line 36 described later.

The combustor 22 mixes and burns the fuel gas L1, a part of the air A, the exhaust fuel gas L3, and the exhaust air A2 to generate the combustion gas G. The combustion gas G is supplied to the turbine 23 through the combustion gas supply line 28. The turbine 23 rotates due to the adiabatic expansion of the combustion gas G, and the exhaust gas is discharged from the combustion exhaust gas line 55. The generator 12 is provided coaxially with the turbine 23, and generates electricity by rotationally driving the turbine 23.

The fuel gas L1 supplied to the combustor 22 and the fuel gas L2 described later are flammable gases, for example, gas such as coal gas produced by gasifying a carbonaceous raw material, carbon monoxide (CO) and methane. Hydrocarbon gas such as (CH ₄ ), liquefied natural gas (LNG), city gas, hydrogen (H ₂ ), methanol, petroleum and the like are used. As the fuel gases L1 and L2 in the present embodiment, for example, city gas is used, and fuel gas containing methane as a main component is used. The fuel gases L1 and L2 do not necessarily have to be the same gas, and different gases may be used.

The SOFC 13 is configured by accommodating a fuel electrode 13A, an air electrode 13B, and a solid electrolyte 111 (see FIG. 2) in a pressure vessel. The detailed configuration of SOFC 13 will be described later.
The SOFC 13 reacts at a predetermined operating temperature to generate electricity by supplying an oxidizing agent gas to the air electrode 13B and supplying a fuel gas (reducing agent gas) to the fuel electrode 13A.
The oxidant gas is, for example, a gas containing approximately 15% to 30% of oxygen, and air is typically preferable. However, in addition to air, a mixed gas of combustion exhaust gas and air or a mixed gas of oxygen and air is used. Etc. can be used. In the present embodiment, a case where at least a part of the air A compressed by the compressor 21 is adopted as the oxidant gas supplied to the SOFC 13 will be illustrated and described.

Air (oxidizer gas) A1 is supplied to the SOFC 13 as an oxidant gas through the second air supply line 31 branched from the first air supply line 26 to the air supply unit which is the introduction portion of the air electrode 13B. The second air supply line 31 is provided with a control valve 64 for adjusting the flow rate of the supplied air A1. Further, in the first air supply line 26, a heat exchanger 58 is provided on the upstream side (in other words, the compressor 21 side) of the air A1 from the branch point of the second air supply line 31. In the heat exchanger 58, the air A is heat-exchanged with the exhaust gas discharged from the combustion exhaust gas line 55 to raise the temperature. Further, the second air supply line 31 is provided with a bypass line 62 that bypasses the heat exchanger 58. The bypass line 62 is provided with a control valve 66 so that the bypass flow rate of the air A can be adjusted. By controlling the opening degree of the control valves 64 and 66 by the control device 60 described later, the flow rate ratio of the air A passing through the heat exchanger 58 and the air A bypassing the heat exchanger 58 is adjusted, and the second The temperature of the air A1 supplied to the SOFC 13 through the air supply line 31 is adjusted.
The temperature of the air A1 supplied to the SOFC 13 does not damage the constituent materials of the SOFC cartridge 203, including the air supply section for introducing the air A1 into the SOFC cartridge 203 (see FIG. 3) constituting the SOFC 13 and the air supply branch pipe. The upper limit of temperature is limited.

Further, an air electrode fuel supply line 80 that supplies the fuel gas L2 as a flammable gas is connected to the second air supply line 31. The air electrode fuel supply line 80 is provided with a control valve 82 for adjusting the amount of fuel gas supplied to the second air supply line 31. By controlling the valve opening degree of the control valve 82 by the control device 60 described later, the supply amount of the fuel gas L2 added to the air A1 is adjusted. The amount of the fuel gas L2 added to the air A1 is supplied at a flammable limit concentration or less, and more preferably at 3% by volume or less.

An exhaust air discharge line 34 for discharging the exhaust air A2 used in the air electrode 13B is connected to the SOFC 13. An exhaust air supply line 36 for supplying the exhaust air A2 to the combustor 22 is connected to the exhaust air discharge line 34. The exhaust air supply line 36 is provided with a shutoff valve 38 for disconnecting the system between the SOFC 13 and the MGT 11.
Further, the exhaust air discharge line 34 is provided with a control valve (or shutoff valve) 37 for adjusting the amount of exhaust air discharged to the outside.

The SOFC 13 is further subjected to a second fuel gas supply line 41 for supplying the fuel gas L2 to the fuel gas supply unit 207 (see FIG. 3) which is an introduction unit of the fuel electrode 13A, and after being used for the reaction at the fuel electrode 13A. It is connected to the exhaust fuel gas line 43 that discharges the exhaust fuel gas L3. The second fuel gas supply line 41 is provided with a control valve 42 for adjusting the flow rate of the fuel gas L2 supplied to the fuel electrode 13A, and the exhaust fuel gas line 43 adjusts the amount of exhaust fuel gas discharged to the outside. A control valve (or shutoff valve) 46 is provided for this purpose. The excess pressure can be quickly adjusted by the control valve (or shutoff valve) 46 of the exhaust fuel gas line 43 and the control valve (or shutoff valve) 37 of the exhaust air discharge line 34. Further, the fuel air differential pressure between the fuel electrode 13A and the air electrode 13B of the SOFC 13 is controlled by the control valve 47 so that the fuel electrode 13A side becomes higher in a predetermined pressure range. Further, a fuel gas recirculation line 49 for recirculating the exhaust fuel gas L3 to the inlet of the fuel electrode 13A of the SOFC 13 is connected to the exhaust fuel gas line 43. The fuel gas recirculation line 49 is provided with a recirculation blower 50 for recirculating the exhaust fuel gas L3.

Further, the fuel gas recirculation line 49 is provided with a pure water supply line 44 for supplying pure water for reforming the fuel gas L2 to the fuel electrode 13A. A pump 48 is provided on the pure water supply line 44. By controlling the discharge flow rate of the pump 48 by the control device 60, the pure water flow rate supplied to the fuel electrode 13A is adjusted.

[SOFC configuration]
Next, the configuration of the SOFC 13 will be described with reference to FIGS. 2 to 4.
First, a cylindrical cell stack used for SOFC of the SOFC combined cycle power generation system (fuel cell combined cycle power generation system) according to the present embodiment will be described with reference to FIG. FIG. 2 is a diagram showing one aspect of the cell stack 101 according to the present embodiment. The cell stack 101 includes a cylindrical base tube 103, a plurality of fuel cell 105 formed on the outer peripheral surface of the base tube 103, and an interconnector 107 formed between adjacent fuel cell 105. The fuel cell 105 is formed by laminating a fuel electrode 13A, a solid electrolyte 111, and an air electrode 13B. Further, the cell stack 101 is an air electrode 13B of the fuel cell 105 formed at one end of the plurality of fuel cell 105 formed on the outer peripheral surface of the base tube 103 in the longitudinal axis direction of the base tube 103. The lead film 115 is electrically connected to the fuel cell 105 at the other end of the fuel cell 105, and is electrically connected to the fuel pole 13A of the fuel cell 105 (not shown). To be equipped.

Substrate tube 103 is made of a porous material, for example, CaO-stabilized _ZrO 2 (CSZ), a mixture of CSZ and nickel oxide (NiO) (CSZ + NiO) , or _Y 2 _{O 3} stabilized ZrO ₂ (YSZ), or The main component is MgAl ₂ O _{4 and the} like. The base tube 103 supports the fuel cell 105, the interconnector 107, and the lead film 115, and the fuel gas supplied to the inner peripheral surface of the base tube 103 is supplied to the inner peripheral surface of the base tube 103 through the pores of the base tube 103. It is diffused into the fuel electrode 13A formed on the outer peripheral surface of the fuel cell.

The fuel electrode 13A is composed of an oxide of a composite material of Ni and a zirconia-based electrolyte material, and for example, Ni / YSZ is used. The thickness of the fuel electrode 13A is 50 to 250 μm. In this case, in the fuel electrode 13A, Ni, which is a component of the fuel electrode 13A, has a catalytic action on the fuel gas. This catalytic action reacts a fuel gas supplied via the substrate tube 103, for example, a mixed gas of methane (CH ₄ ) and water vapor, and reforms it into hydrogen (H ₂ ) and carbon monoxide (CO). .. Further, the fuel electrode 13A is an interface between hydrogen (H ₂ ) and carbon monoxide (CO) obtained by reforming and oxygen ions (O ^2- ) supplied via the solid electrolyte 111 with the solid electrolyte 111. It reacts electrochemically in the vicinity to produce water (H ₂ O) and carbon dioxide (CO ₂ ). At this time, the fuel cell 105 generates electricity by the electrons emitted from the oxygen ions.

The solid electrolyte 111 is mainly composed of YSZ having airtightness that does not allow gas to pass through and high oxygen ion conductivity at high temperature. The solid electrolyte 111 moves oxygen ions (O ^2- ) generated at the air electrode 13B to the fuel electrode. The film thickness of the solid electrolyte 111 located on the surface of the fuel electrode 13A is 10 to 100 μm.

The air electrode 13B is composed of, for example, a LaSrMnO _3- based oxide or a LaCoO _3- based oxide. The air electrode 13B dissociates oxygen in the supplied oxidant gas such as air in the vicinity of the interface with the solid electrolyte 111 to generate oxygen ions (O ^2- ). The air electrode 13B may have a two-layer structure. In this case, the air electrode layer (air electrode intermediate layer) on the solid electrolyte 111 side is made of a material having high ionic conductivity and excellent catalytic activity. The air electrode layer (air electrode conductive layer) on the air electrode intermediate layer may be composed of a perovskite-type oxide represented by Sr and Ca-doped LaMnO ₃ . By doing so, the power generation performance can be further improved.

The interconnector 107 is composed of a conductive perovskite-type oxide represented by M _1-x L _x TiO ₃ (M is an alkaline earth metal element and L is a lanthanoid element) such as SrTiO ₃ system. The interconnector 107 has a dense film so that the fuel gas and air do not mix with each other, and has stable durability and electrical conductivity in both an oxidizing gas atmosphere and a reducing gas atmosphere. In the adjacent fuel cell 105, the interconnector 107 electrically connects the air electrode 13B of one fuel cell 105 and the fuel electrode 13A of the other fuel cell 105, and the adjacent fuel cell 105 are connected to each other. Are connected in series. Since the lead film 115 needs to have electron conductivity and a coefficient of thermal expansion close to that of other materials constituting the cell stack 101, Ni such as Ni / YSZ and a zirconia-based electrolyte material are used. It is composed of a composite material. The lead film 115 derives the DC power generated by the plurality of fuel cell 105s connected in series by the interconnector to the vicinity of the end of the cell stack 101.

Next, the SOFC module and the SOFC cartridge according to the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a view showing one aspect of the SOFC module according to the present embodiment, and FIG. 4 is a cross-sectional view of one aspect of the SOFC cartridge according to the present embodiment.

As shown in FIG. 3, the SOFC module 201 includes, for example, a plurality of SOFC cartridges 203 and a pressure vessel 205 for accommodating the plurality of SOFC cartridges 203. Although FIG. 3 illustrates a cylindrical SOFC cell stack, this does not necessarily have to be the case, and for example, a flat cell stack may be used. Since the pressure vessel 205 is operated at an internal pressure of 0.1 MPa to about 1 MPa and an internal temperature of atmospheric temperature to about 550 ° C., it has resistance and corrosion resistance to an oxidant gas such as oxygen contained in the oxidant gas. The material that owns is used. For example, a stainless steel material such as SUS304 is suitable.

The SOFC module 201 includes a fuel gas supply unit 207 and a plurality of fuel gas supply branch pipes 207a, and a fuel gas discharge unit 209 and a plurality of fuel gas discharge branch pipes 209a. Further, the SOFC module 201 includes an air supply unit (not shown), an air supply branch pipe (not shown), an air discharge unit (not shown), and a plurality of air discharge branch pipes (not shown).

The fuel gas L2 from the second fuel gas supply line 41 (see FIG. 1) is supplied to the plurality of SOFC cartridges 203 through the fuel gas supply unit 207 and the plurality of fuel gas supply branch pipes 207a. The fuel gas supply branch pipe 207a guides the fuel gas L2 supplied through the fuel gas supply unit 207 to the plurality of SOFC cartridges 203 at a substantially equal flow rate, and substantially equalizes the power generation performance of the plurality of SOFC cartridges 203.

The exhaust fuel gas L3 discharged from the SOFC cartridge 203 is guided to the exhaust fuel gas line 43 (see FIG. 1) at a substantially equal flow rate by passing through the fuel gas discharge branch pipe 209a and the fuel gas discharge unit 209.

In the present embodiment, a mode in which a plurality of SOFC cartridges 203 are assembled and stored in the pressure vessel 205 is described, but the present invention is not limited to this, and for example, the SOFC cartridge 203 is not assembled and is stored in the pressure vessel 205. It may be stored inside.

As shown in FIG. 4, the SOFC cartridge 203 includes a plurality of cell stacks 101, a power generation chamber 215, a fuel gas supply chamber 217, a fuel gas discharge chamber 219, an air supply chamber 221 and an air discharge chamber 223. I have. Further, the SOFC cartridge 203 includes an upper tube plate 225a, a lower tube plate 225b, an upper heat insulating body 227a, and a lower heat insulating body 227b. In the present embodiment, the SOFC cartridge 203 is provided with the fuel gas by arranging the fuel gas supply chamber 217, the fuel gas discharge chamber 219, the air supply chamber 221 and the air discharge chamber 223 as shown in FIG. The structure is such that air as an oxidant gas flows opposite to the inside and outside of the cell stack 101, but the embodiment is not necessarily limited to this example, and for example, the inside and outside of the cell stack are parallel to each other. Or the air may flow in a direction orthogonal to the longitudinal axis direction of the cell stack.

The power generation chamber 215 is a region formed between the upper heat insulating body 227a and the lower heat insulating body 227b. The power generation chamber 215 is an area in which the fuel cell 105 of the cell stack 101 is arranged, and is an area in which fuel gas and air are electrochemically reacted to generate electricity. For example, the temperature near the central portion of the cell stack 101 in the power generation chamber 215 in the longitudinal direction is monitored by a temperature sensor 92 or the like, which will be described later, and becomes a high temperature atmosphere of about 700 ° C. to 1000 ° C. during steady operation of the SOFC module 201.

The fuel gas supply chamber 217 is an area surrounded by the upper casing 229a and the upper pipe plate 225a of the SOFC cartridge 203, and the fuel gas supply branch pipe 207a is provided by the fuel gas supply hole 231a provided in the upper part of the upper casing 229a. Is communicated with. The plurality of cell stacks 101 are joined to the upper pipe plate 225a by the seal member 237a, and the fuel gas supply chamber 217 receives the fuel gas supplied from the fuel gas supply branch pipe 207a through the fuel gas supply hole 231a. It is guided inside the base tubes 103 of the plurality of cell stacks 101 at a substantially uniform flow rate, and the power generation performance of the plurality of cell stacks 101 is substantially made uniform.

The fuel gas discharge chamber 219 is an area surrounded by the lower casing 229b and the lower pipe plate 225b of the SOFC cartridge 203, and the fuel gas discharge branch pipe 209a is provided by the fuel gas discharge hole 231b provided in the lower part of the lower casing 229b. Is communicated with. The plurality of cell stacks 101 are joined by a lower pipe plate 225b and a sealing member 237b, and the fuel gas discharge chamber 219 passes through the inside of the base pipe 103 of the plurality of cell stacks 101 and is supplied to the fuel gas discharge chamber 219. The exhaust fuel gas L3 to be generated can be aggregated and led to the fuel gas discharge branch pipe 209a through the fuel gas discharge hole 231b.

The air supply chamber 221 is an area surrounded by the lower casing 229b, the lower pipe plate 225b, and the lower heat insulating body 227b of the SOFC cartridge 203, and is illustrated by the air supply hole 233a provided on the side surface of the lower casing 229b. Not communicated with the air supply branch pipe. The air supply chamber 221 can guide a predetermined flow rate of air supplied from an air supply branch pipe (not shown) through the air supply hole 233a to the power generation chamber 215 through the air supply gap 235a at a substantially uniform flow rate.

The air discharge chamber 223 is an area surrounded by the upper casing 229a of the SOFC cartridge 203, the upper pipe plate 225a, and the upper heat insulating body 227a, and is illustrated by the air discharge holes 233b provided on the side surface of the upper casing 229a. It is communicated with the air discharge branch pipe. The air discharge chamber 223 can guide the exhaust air supplied from the power generation chamber 215 to the air discharge chamber 223 through the air discharge gap 235b to an air discharge branch pipe (not shown) through the air discharge hole 233b.

The DC power generated in the power generation chamber 215 is led out to the vicinity of the end of the cell stack 101 by a lead film 115 (see FIG. 2) made of Ni / YSZ or the like provided in the plurality of fuel cell 105, and then the SOFC cartridge. The current is collected by the current collecting rod (not shown) of 203 via the current collecting plate (not shown), and is taken out to the outside of each SOFC cartridge 203. The electric power led out to the outside of the SOFC cartridge 203 is led out to the outside of the SOFC module 201, converted into AC power by a power conversion device such as a power conditioner, and is converted into AC power to a power supply destination (for example, load equipment or power system). ) Is supplied.

As described above, in the SOFC 13 according to the present embodiment, the fuel gas L2 and the air A1 flow so as to face the inside and the outside of the cell stack 101. As a result, the exhaust air A2 exchanges heat with the fuel gas L2 supplied to the power generation chamber 215 through the inside of the base pipe 103, and the upper pipe plate 225a and the like made of a metal material are deformed such as buckling. It is cooled to a temperature that does not allow it to be supplied to the air discharge chamber 223. Further, the fuel gas L2 is heated by heat exchange with the exhaust air A2 discharged from the power generation chamber 215 and supplied to the power generation chamber 215. As a result, the fuel gas L2 preheated to a temperature suitable for power generation can be supplied to the power generation chamber 215 without using a heater or the like. Further, the exhaust fuel gas L3 that has passed through the inside of the base pipe 103 and passed through the power generation chamber 215 is heat-exchanged with the air A1 supplied to the power generation chamber 215, and the lower pipe plate 225b and the like made of a metal material are formed. It is cooled to a temperature at which it does not deform such as buckling and is supplied to the fuel gas discharge chamber 219. Further, the air A1 is heated by heat exchange with the exhaust fuel gas L3 and supplied to the power generation chamber 215. As a result, air heated to a temperature required for power generation can be supplied to the power generation chamber 215 without using a heater or the like.

As shown in FIG. 1, the power generation system 10 is provided with various sensors at each location. For example, the power generation system 10 is provided with a differential pressure sensor 90 and temperature sensors 92 to 97. The differential pressure sensor 90 measures the differential pressure between the fuel electrode 13A and the air electrode 13B. The temperature sensor 92 measures the temperature of the power generation room. The temperature sensor 93 is provided on the recirculation blower 50 and measures the bearing temperature of the recirculation blower 50. The temperature sensor 94 is provided near the suction port of the compressor 21 of the MGT 11 and measures the outside air temperature, which is the temperature of the air A sucked by the compressor 21. The temperature sensor 95 is provided in the exhaust fuel gas line 43 and measures the exhaust fuel outlet temperature. The temperature sensor 96 is provided on the exhaust air discharge line 34 and measures the exhaust air outlet temperature. The temperature sensor 97 is provided in the second air supply line 31 and measures the inlet air temperature. Further, the various control valves included in the power generation system 10 are provided with a valve opening degree detecting unit (not shown) for detecting the valve opening degree of the various control valves.

Further, the above-mentioned various sensors are an example, and the power generation system 10 is provided with various sensors for acquiring various data necessary for normal operation of the power generation system 10, various sensors for detecting an abnormality, and the like. Has been done. The measurement data measured by these various sensors is transmitted to the control device 60.

The control device 60 performs arithmetic processing based on the measurement data, and controls the operation of each part of the power generation system 10 so as to satisfy the required load, which is the power generation load required for the SOFC 13. Further, the control device 60 monitors whether or not an abnormality has occurred in the SOFC 13 based on the measurement data, and when the abnormality is detected, executes the protection control described below.

[Protective control of power generation system]
[First Embodiment]
Next, a first embodiment of protection control executed by the control device 60 of the power generation system 10 having the above configuration will be described.
The control device 60 is, for example, a computer or a sequencer, and has a CPU, a ROM (Read Only Memory) for storing a program executed by the CPU, and a RAM (Random Access Memory) that functions as a work area when each program is executed. ) Etc. are provided. A series of processing processes for realizing various functions described later is recorded in a recording medium or the like in the form of a program, and the CPU reads this program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions described later are realized.

FIG. 5 is a functional block diagram showing mainly the functions related to protection control among various functions included in the control device 60. As shown in FIG. 5, the control device 60 includes an abnormality determination unit 141, an output control unit 142, and an abnormality elimination determination unit 143.

The abnormality determination unit 141 determines whether or not a specific abnormality has occurred in the power generation system 10 based on the above-mentioned measurement data. Here, the "specific abnormality" is an abnormality that may be resolved by increasing or decreasing the load of the SOFC 13, and more specifically, an abnormality relating to an increase or decrease in the temperature of the power generation chamber 215. Here, the “load” is the power generation output of the SOFC 13, and corresponds to the output current of the SOFC 13 in the present embodiment.
The abnormality determination unit 141 includes, for example, abnormality determination information in which determination criteria for determining that a specific abnormality has occurred are described, and the measurement data received from various sensors and the abnormality determination information are used. Determine if a particular anomaly has occurred.

In the present embodiment, for example, the abnormality determination information describes a plurality of conditions (1) to (9) for determining that a specific abnormality has occurred. The abnormality determination unit 141 determines that a specific abnormality has occurred when any one of the plurality of conditions described in the abnormality determination information is met. The conditions shown below are an example, and the judgment criteria for determining a specific abnormality are not limited to this example.

(1) When the state where the temperature of the power generation room is equal to or higher than the first threshold is maintained for the first predetermined period (2) When the state where the internal temperature of the recirculation blower 50 is equal to or higher than the second threshold is maintained for the second predetermined period (3) ) When the exhaust fuel outlet temperature is maintained above the third threshold value for the third predetermined period (4) When the exhaust air outlet temperature is maintained above the fourth threshold value for the fourth predetermined period (5) Air utilization rate When the state where is above the fifth threshold value is maintained for the fifth predetermined period (6) When the state where the outside air temperature is above the sixth threshold value is maintained for the sixth predetermined period (7) The valve opening degree of the control valve 47 is the third When the state of 7 thresholds or more is maintained for the 7th predetermined period (8) When the valve opening degree of the control valve 47 is maintained for the 8th predetermined period of the 8th threshold or less (9) The power generation room temperature is the 9th threshold When the following conditions are maintained for the 9th predetermined period

The threshold values for the conditions (1) to (9) and each predetermined period in the present embodiment are shown below as examples.
The first threshold value is set, for example, in a temperature range of 101% or more and 105% or less of the power generation room temperature at the rated load.
The first predetermined period is set, for example, in the range of 60 seconds or more and 400 seconds or less.
The second threshold value is set, for example, in a temperature range of 101% or more and 120% or less of the internal temperature of the recirculation blower at the rated load.
The second predetermined period is set, for example, in the range of 60 seconds or more and 400 seconds or less.
The third threshold value is set, for example, in a temperature range of 101% or more and 120 or less of the exhaust fuel outlet temperature at the rated load.
The third predetermined period is set, for example, in the range of 60 seconds or more and 400 seconds or less.

The fourth threshold value is set, for example, in a temperature range of 101% or more and 120% or less of the exhaust air outlet temperature at the rated load.
The fourth predetermined period is set, for example, in the range of 60 seconds or more and 400 seconds or less.
The fifth threshold value is set, for example, in the air utilization rate range of 101% or more and 120% or less of the air utilization rate at the rated load.
The fifth predetermined period is set, for example, in the range of 60 seconds or more and 400 seconds or less.
The sixth threshold value is set, for example, in a temperature range of 40 ° C. or higher and 50 ° C. or lower.
The sixth predetermined period is set, for example, in the range of 60 seconds or more and 400 seconds or less.

The seventh threshold value is set, for example, in a valve opening range of 90% or more and 100% or less.
The seventh predetermined period is set, for example, in the range of 30 seconds or more and 200 seconds or less.
The eighth threshold value is set, for example, in a valve opening range of 1% or more and 10% or less.
The eighth predetermined period is set, for example, in the range of 30 seconds or more and 200 seconds or less.
The ninth threshold value is set, for example, in a temperature range of 80% or more and 90% or less of the temperature of the power generation room at the rated load.
The ninth predetermined period is set, for example, in the range of 60 seconds or more and 200 seconds or less.

When the abnormality determination unit 141 determines that a specific abnormality has occurred, the output control unit 142 increases or decreases the load by a predetermined amount according to the cause of the occurrence of the abnormality. Specifically, among the above conditions, the conditions (1) to (8) are considered to be due to the increase in the temperature of the power generation room, and the conditions (9) are considered to be due to the decrease in the temperature of the power generation room.

For example, the conditions (1) to (4) are considered to be phenomena caused by an increase in the temperature of the power generation chamber. By reducing the load of the SOFC 13, the power generation reaction can be lowered and the amount of heat generated by the power generation reaction can be reduced. As a result, the temperature of the power generation room can be lowered. By lowering the load and lowering the temperature of the power generation chamber in this way, it can be expected that the abnormalities related to (1) to (4) will be eliminated.

Further, regarding the conditions (5) and (6), it is considered that the temperature of the power generation chamber rises due to the relative decrease in the supply amount of the air A1 supplied to the air electrode 13B. That is, since the air A1 supplied to the air electrode 13B acts as a coolant, the temperature of the power generation chamber rises as the supply amount of the air A1 decreases. Further, when the outside air temperature measured by the outside air temperature sensor 94 rises, the air density decreases and the supply amount of the air A1 decreases, so that the power generation room temperature rises. Even in such a case, by reducing the load, the oxidant gas (oxygen in the air) required for power generation is reduced, so that the amount of air that contributes to cooling the temperature of the power generation room can be substantially increased. The temperature of the power generation room can be lowered. As described above, with respect to the conditions (5) and (6), the abnormality can be expected to be eliminated by lowering the load and lowering the temperature of the power generation chamber.

Here, the air utilization rate is a value obtained by dividing the amount of oxygen consumed by power generation by the amount of oxygen supplied to the air electrode, that is, the amount of oxygen supplied in the air A1 supplied to the air electrode 13B.
The oxygen consumption due to power generation includes, for example, an oxygen flow rate calculated using the flow rate and oxygen concentration of air A1 supplied to the air electrode 13B, and an oxygen flow rate calculated using the flow rate and oxygen concentration of exhaust air A2. It can be obtained by the difference of. Further, as another calculation example of the oxygen consumption by power generation, for example, by using the fuel flow rate and gas composition supplied to the fuel electrode 13A and the flow rate and gas composition of the exhaust fuel gas L3, the reacted fuel component can be obtained. Examples thereof include a method of calculating from this quantitative reaction amount, a method of calculating using the current value, the flow rate and oxygen concentration of air A1, and the quantitative reaction amount.
The amount of oxygen supplied to the air electrode 13B can be calculated using, for example, the flow rate and oxygen concentration of the air A1 supplied to the air electrode 13B.

Regarding the condition (7), the fuel air differential pressure between the fuel electrode 13A and the air electrode 13B of the SOFC 13 is controlled by the control valve 47 so that the fuel electrode 13A side becomes higher in a predetermined pressure range, such as pipe blockage. Is considered as one of the factors. If the power generation reaction decreases due to the decrease in the load of the SOFC 13, the flow rate of the exhaust fuel gas discharged to the exhaust fuel gas line 43 decreases. As a result, the pressure loss due to the pipe blockage or the like is alleviated, the opening degree of the control valve 47 can be reduced, and the abnormality related to the condition (7) can be expected to be eliminated.
Further, regarding the condition (8), it is considered that one of the factors is that the airtightness between the fuel electrode 13A and the air electrode 13B is lowered. Therefore, regarding the condition (8), if the cell or a part of the support portion of the cell is damaged, the differential pressure may not be recovered, but due to, for example, the seal position deviation of the seal members 237a and 237b. In that case, it is possible that the abnormality can be resolved by reducing the load and changing the state of the power generation chamber.
Regarding the condition (9), for example, the temperature of the power generation chamber is lowered due to the fact that the fuel inlet temperature is lowered due to the influence of supplying pure water which is the reforming water to be supplied to the fuel electrode 13A. It is thought that there is. Therefore, contrary to the cases (1) to (8) described above, by increasing the load, the amount of heat generated by the power generation reaction is increased, and by raising the temperature of the power generation chamber, the abnormality can be expected to be resolved.

As described above, the output control unit 142 gradually reduces the load by a predetermined amount when any of the conditions (1) to (7) is met. For example, after reducing the target load by a predetermined amount and holding the state for a predetermined period, the process of further reducing the target load by a predetermined amount is repeated until the target load reaches a predetermined protection lower limit value. Further, in the process of lowering the load to the lower limit of protection, when the abnormality elimination determination unit 143, which will be described later, determines that the abnormality has been eliminated, the output control unit 142 determines that the abnormality has been eliminated. maintain.

Here, the above-mentioned "predetermined amount" when changing the target load is set to be equal to or larger than the desired change range in which the temperature of the power generation chamber is lowered to the extent that it contributes to the elimination of the abnormality. In the present embodiment, the "predetermined amount" is set in the range of 5% or more and 15% or less with respect to the rated load, for example.
Further, the "predetermined period" to be retained is set to be longer than the time during which the abnormality can be confirmed with respect to the time delay to the follow-up response such as the temperature and pressure of the power generation system 10, as will be described later, and after the change. By maintaining the target load of, the power generation system 10 is set within the time range that does not lead to failure.
The "predetermined amount" does not necessarily have to be the same value at each stage of the load change. The predetermined amount may be increased little by little or decreased little by little in consideration of the responsiveness of the power generation system 10 according to each step and the target load.
Further, the "protection lower limit value" may be set to, for example, a load that does not need to supply pure water, which is reforming water, to the fuel electrode 13A. For example, in a load region where the load is equal to or higher than a predetermined value, the amount of water vapor generated in the power generation reaction is large, so that the amount of water vapor contained in the exhaust fuel gas of SOFC 13 is large. Therefore, the water vapor contained in the exhaust fuel gas re-injected into the fuel electrode 13A through the fuel gas recirculation line 49 can supply the reforming water required for reforming. However, when the load of the SOFC 13 decreases, the amount of water vapor generated by the power generation reaction decreases, so that the amount of water vapor circulating in the fuel gas recirculation line 49 decreases, and the amount of water vapor required for reforming cannot be covered. Therefore, when the load is equal to or less than a predetermined value, pure water is supplied from the outside via the pure water supply line 44 to supplement the shortage of water vapor. Here, the load when pure water is supplied from the pure water supply line 44 is set to a predetermined value in the range of, for example, 40% or more and 50% or less of the rated load. Here, in a load that requires the supply of pure water, the input of pure water may cause pressure fluctuations, flow rate fluctuations, etc. in each system of the power generation system 10. Therefore, in the present embodiment, the lower limit of protection is set to pure water. Is set to more than the unnecessary load. That is, in the present embodiment, the "protection lower limit value" is set to, for example, a load of a predetermined value or more in the range of 40% or more and 50% or less of the rated load, and each system of the power generation system 10 is abnormal in a stable state. It is possible to judge whether or not the problem has been resolved.

Further, when the abnormality determination unit 141 determines that the condition (8) is satisfied, the output control unit 142 does not gradually reduce the load by a predetermined amount, but at once to the lower limit of protection. Decrease. That is, when the condition (8) is satisfied, it is considered that the airtightness between the fuel electrode 13A and the air electrode 13B may not be ensured as described above, so that the load is gradually applied. Even if the load is lowered or the load is lowered to the lower limit of the load at one time, it is highly possible that the result of whether or not the abnormality is resolved does not change. Therefore, when the condition (8) is met, unlike the cases (1) to (7), for example, the load is continuously reduced to the lower limit of protection at a predetermined rate of change, and the target load is protected. When a predetermined period has elapsed after reaching the lower limit value, the abnormality resolution determination unit 143 determines the abnormality resolution.

Further, when the abnormality determination unit 141 determines that the condition (9) is satisfied, the output control unit 142 raises the load stepwise by a predetermined amount up to the protection upper limit value. The "stepwise" and "predetermined amount" here are as described above.
Here, the "protection upper limit value" is set to be equal to or higher than the load in which the supply of pure water, which is the reforming water to be supplied to the fuel electrode 13A, is not required, the fuel inlet temperature does not decrease, and the power generation room temperature does not decrease. At the same time, it is set within the range below the rated load. In the present embodiment, the value is set in the range of 100% or less of the rated load at a value between 40% and 50% of the rated load.

When the load is changed by a predetermined amount by the output control unit 142, the abnormality elimination determination unit 143 determines whether or not the abnormality has been resolved after the changed load is held for a predetermined period. The "predetermined period" is set to be longer than the time during which abnormality resolution can be confirmed with respect to the time delay to the follow-up response such as temperature and pressure of the power generation system 10, and the power generation system is maintained by holding the changed load. 10 is set in the range of time or less that does not lead to failure.
For example, in the case of the power generation room temperature, this "predetermined period" is set to be longer than the time required for the power generation room temperature to change and stabilize in accordance with the load change after the target load is lowered or raised. .. Since the power generation room temperature has a large heat capacity, there is a delay in responding to changes in the load. The predetermined period is set in consideration of this response delay, and in the present embodiment, it is set in the range of, for example, 60 seconds or more and 400 seconds or less.

Next, the protection control method of the power generation system according to the present embodiment will be described with reference to FIG.
First, the above measurement data is input (step SA1), and it is determined whether or not a specific abnormality has occurred based on these measurement data (step SA2). As a result, if it is determined that no specific abnormality has occurred (“NO” in step SA2), monitoring is continued. On the other hand, when it is determined in step SA2 that a specific abnormality has occurred (“YES” in step SA2), the load is reduced or increased according to the cause of the abnormality (step SA3). Specifically, when the above conditions (1) to (8) are met, an increase in the temperature of the power generation chamber is considered to be a factor. Therefore, when the target load is reduced by a predetermined amount and the condition (9) is met. Is considered to be due to a decrease in the temperature of the power generation room, so the target load is increased by a predetermined amount. If the condition (8) is met, the target load is reduced to the lower limit of protection.

Subsequently, when the target load is lowered or raised and the state is maintained for a predetermined period (step SA4), it is determined whether or not the abnormality has been resolved (step SA5). Here, the "predetermined period" in step SA4 is set according to the cause of the abnormality that has occurred, and may be different depending on the above conditions (1) to (9).

If the abnormality is not resolved in step SA5 (“NO” in step SA5), it is determined whether or not the load is the protection lower limit value or the protection upper limit value (step SA6). As a result, if the load is not the protection lower limit value or the protection upper limit value (“NO” in step SA6), the process returns to step SA3, and the subsequent processing is repeated. On the other hand, in step SA6, when the load is the protection lower limit value or the protection upper limit value, it is determined that it is difficult to resolve the abnormality, and the operation of the SOFC 13 is stopped (step SA7).

On the other hand, if it is determined in step SA5 that the abnormality has been resolved, an operation for maintaining the current load is performed (step SA8). Subsequently, it is determined whether or not the abnormality that occurred this time does not recur while the load is maintained, in other words, whether or not the root cause of the specific abnormality that has occurred this time is eliminated (step SA9). For example, when the abnormality that occurred this time is eliminated by the operator (for example, when the measured value shows an abnormal value due to a failure of the temperature sensor, the measured value of this temperature sensor is replaced with the design value. Is performed, etc.), it is determined that the abnormality that occurred this time does not recur (“YES” in step SA9), and the SOFC load is increased according to the required load, which is the power generation load required for the SOFC 13. Alternatively, the temperature is lowered to shift to normal operation (step SA10).
On the other hand, if it is not determined in step SA9 that the specific abnormality that occurred this time does not recur (“NO” in step SA9), the current load is until it is determined that the specific abnormality that occurred this time does not recur. Is maintained.

FIG. 7 is a diagram showing an example of a temporal transition of the target load when an abnormality corresponding to any of the conditions (1) to (7) occurs among the above conditions (1) to (9). ..
For example, at time t1 in FIG. 7, when it is determined that a specific abnormality has occurred by satisfying any of the conditions (1) to (7), a predetermined amount of the target load (for example, 10% with respect to the rated load) is determined. Is shown) is reduced by a predetermined load change rate (for example, several% / minute of the rated load). The predetermined load change rate is appropriately set in consideration of the responsiveness of the power generation system 10 to the load change control. Then, when the target load drops by a predetermined amount at time t2, this state is maintained for a predetermined period. Then, at the time t3 when the holding for the predetermined period has elapsed, it is determined whether or not the abnormality has been resolved. As a result, if the abnormality is not resolved, the target load is further reduced by a predetermined amount. Then, when the target load drops by a predetermined amount at time t4, this state is maintained for a predetermined period. Then, at time t5 when the holding for a predetermined period has elapsed, it is determined whether or not the abnormality has been resolved. As a result, if the abnormality is resolved, the current target load is maintained. Then, at time t6, for example, when the operator inputs that the cause of this abnormality has been eliminated, the output control unit 142 determines that the abnormality that has occurred this time does not recur, and sets the target load as the required load. Set the value according to the value (for example, rated load), and increase the target load at a predetermined load change rate toward the rated load. Then, when the target load reaches the required load at time t7, the state is maintained until the required load changes.

In the above example, the predetermined period (for example, the period of time t2 to t3 and the period of time t4 to t5) does not necessarily have to be the same period every time. For example, the predetermined period may be changed according to the target load.
Further, under the same target load, the abnormality resolution determination unit 143 may determine the abnormality resolution a plurality of times during a predetermined period. As a result, the reliability of the determination result as to whether or not the abnormality has been resolved can be improved.

As described above, according to the fuel cell control device, the fuel cell protection control method, and the power generation system according to the present embodiment, a specific abnormality that may be resolved by increasing or decreasing the load occurs. If so, the load is increased or decreased depending on the cause of the specific abnormality that has occurred. Then, when the abnormality is resolved by increasing or decreasing the load, the operation is continued with the load when the abnormality is resolved. Therefore, as compared with the conventional power generation system in which the operation is stopped in the event of an abnormality regardless of the cause of the abnormality, it is possible to shorten the operation stop time and increase the amount of generated power. ..

Further, according to the present embodiment, when the load is reduced or increased, the load decrease or load increase is controlled according to the cause of a specific abnormality. For example, the target load is gradually increased or decreased until a specific abnormality is resolved or the target load reaches a predetermined protection upper limit value or a predetermined protection lower limit value. In this way, by gradually reducing or increasing the load while determining whether or not the abnormality has been resolved, it is possible to maintain operation near the load where the abnormality is resolved and protect the target load. It is possible to shorten the time for reducing the power generation output and increase the power that can be output, as compared with the case of determining whether or not the abnormality has been resolved by lowering the value all at once to the lower limit value.

In addition, depending on the cause of the abnormality that has occurred, there are some that the result does not change even if the target load is gradually lowered while confirming whether or not the abnormality is resolved. In such a case, the target load is lowered to the lower limit of protection at once, and the process of gradually changing the load to the predetermined lower limit of protection or the upper limit of protection is omitted to save time. It is possible to confirm in a shorter time whether or not the abnormality can be resolved by the load change. As a result, the amount of generated power can be increased by reducing the power generation output and shortening the time for stopping the operation.

Further, according to the present embodiment, by eliminating the cause causing the specific abnormality, the specific abnormality does not recur while the load is maintained when the specific abnormality is eliminated. When it is determined, the load is recovered from the currently maintained load to a predetermined load (for example, the rated load). Therefore, for example, the load is reduced to zero and the power generation room temperature is lowered to the predetermined load. Compared with the case, the time required for load recovery can be shortened, and the time for zeroing or reducing the power generation output can be shortened to increase the amount of power generated.

[Second Embodiment]
Next, a second embodiment of protection control executed by the control device 60 of the power generation system 10 having the above configuration will be described. In the second embodiment, as in the first embodiment, when a specific abnormality that may be resolved by increasing or decreasing the load occurs, the load is increased according to the cause of the specific abnormality that has occurred. Alternatively, if the abnormality is resolved by increasing or decreasing this load, the operation is continued with the load when the abnormality is resolved, but the part for identifying the cause of the abnormality (step SA9 in the first embodiment). After that) is mainly different. The same configuration as that of the control device 60 according to the first embodiment described above will be designated by the same reference numerals, description thereof will be omitted, and differences will be mainly described.

FIG. 8 is a functional block diagram of the control device 60'according to the second embodiment of the present invention. As shown in FIG. 8, the control device 60'includes the abnormality cause identification unit 144 in addition to the abnormality determination unit 141, the output control unit 142, and the abnormality elimination determination unit 143 described above. When the abnormality determination unit 141 determines that a specific abnormality has occurred, the abnormality cause identification unit 144 identifies the cause of the occurrence of the abnormality.
As shown in FIG. 9, the abnormality cause identification unit 144 includes a storage unit 151, an extraction unit 152, a cause identification unit 153, a cause elimination unit 154, and a display unit 155.

The storage unit 151 stores cause identification information in which information on a specific abnormality is associated with the cause of the specific abnormality. Examples of the information related to the specific abnormality include conditions (1) to (9) of the abnormality determination information used by the abnormality determination unit 141, measurement data in a predetermined period before and after the occurrence of the abnormality, and the like.
Examples of the cause of the specific abnormality include sensor failure, disconnection, pipe damage, auxiliary equipment failure of the recirculation blower 50, control valve 47, and the like.

This cause-specific information is, for example, information created based on past experience. For example, when a specific abnormality has occurred in the past and the cause of the specific abnormality has been clarified, the cause-identifying information is found. It is created by associating information about a specific anomaly with the elucidated cause.
For example, every time a specific abnormality occurs and the cause causing the abnormality is clarified, the cause identification information is created, stored in the storage unit, and stored in a database to generate a similar abnormality. When it occurs, it is possible to easily identify the cause by referring to the past history.

When the abnormality determination unit 141 determines that a specific abnormality has occurred, the extraction unit 152 extracts the cause identification information corresponding to the generated specific abnormality from the storage unit 151.
The cause identification unit 153 identifies the cause that caused the specific abnormality by using the cause identification information extracted by the extraction unit 152.

The cause elimination unit 154 eliminates the cause when the cause identified by the cause identification unit 153 can be eliminated. For example, in the case of a cause related to a sensor failure or disconnection, it is possible to eliminate the cause by performing software processing. For example, measurement data measured by a sensor that has a failure or disconnection is based on design values or simulations. The cause can be eliminated by performing a process of replacing with a value or the like.
On the other hand, in the case of a cause that cannot be eliminated by software, such as a failure of the recirculation blower or a failure of the control valve, the cause elimination unit 154 does not eliminate the cause.

The display unit 155 notifies the operator of the cause of the current abnormality by displaying the cause identified by the cause identification unit 153.

Next, the protection control of the power generation system according to the present embodiment, mainly the identification of the cause, will be described with reference to FIG. The cause identification described below is, for example, a process executed when the control for maintaining the load when the abnormality is resolved is performed in step SA8 of the flowchart shown in FIG.

First, the cause identification information in the storage unit 151 is searched using the information related to the generated abnormality as a key, and the corresponding cause identification information is extracted from the storage unit 151 (step SB1). If the corresponding cause identification information is not stored in the storage unit 151, it is possible to take measures such as displaying the fact on the display unit 155 and notifying the operator.
Next, the cause of this abnormality is identified by referring to the cause described in the extracted cause identification information (step SB2).
Next, it is determined whether or not the identified abnormality can be automatically eliminated (step SB3), and if the cause can be eliminated by software processing, it is determined that the identified abnormality can be automatically eliminated (“YES” in step SB3). The process of eliminating the abnormality is executed (step SB4). For example, if it is related to sensor failure, disconnection, etc., processing to replace the measured value measured by the failed sensor with a design value or a value by simulation, processing to invalidate the measured value of the failed sensor, etc. By doing so, the cause is eliminated.
When the abnormality is eliminated in this way, the load is recovered by increasing or decreasing the load according to the required load (step SB5).

On the other hand, when it is determined in step SB3 that the specified abnormality cannot be automatically eliminated (“NO” in step SB3), for example, when the recirculation blower 50 or various control valves are mechanically failed, the automatic elimination Is determined to be impossible. In this case, the cause of the abnormality is displayed on the display unit 155 and the operator is notified (step SB6).
The operator confirms the cause of the abnormality displayed on the display unit 155, and if the cause can be manually eliminated, the operator manually takes countermeasures to eliminate the cause (step SB7). When the cause is eliminated, the load is recovered in the same manner as in step SB5. If the cause of the displayed abnormality cannot be eliminated manually, the operator decides whether to maintain the operation with the current load or stop the operation according to the importance of the abnormality. The Rukoto. Even if time elapses without the operator making a decision, the presence or absence of an abnormality is detected by another measurement data taken from the power generation system 10. Therefore, if an abnormality occurs in another event, the power generation system Before 10 fails, the operation is stopped and the operation is stopped safely.

As described above, according to the fuel cell control device, the fuel cell protection control method, and the power generation system according to the present embodiment, the cause identification information in which the information on the specific abnormality is associated with the cause of the specific abnormality is previously provided. It is stored in the storage unit 151, and when a specific abnormality occurs, the storage unit 151 is searched using the information related to the specific abnormality as a key, the corresponding abnormality identification information is extracted, and the extracted cause identification information is used. Since the cause of the abnormality is identified by using it, the time required for elucidating the cause of the abnormality and taking measures can be shortened, and the labor required for elucidating the cause can be reduced.

If the cause of the abnormality is a cause that can be eliminated by taking software-like measures, the cause elimination unit 154 automatically eliminates the cause. As a result, even if an abnormality is detected, the cause of the abnormality can be automatically eliminated and the load can be automatically restored, the time for reducing the power generation output can be shortened, and the amount of power generated can be reduced. It is possible to increase it.

Further, when the cause of the abnormality is identified, the cause is displayed on the display unit 155, so that the operator can also confirm the cause of the abnormality. This makes it possible for the operator to take appropriate measures against the abnormalities that have occurred without having to clarify the abnormalities themselves, reduce the power generation output, shorten the time to stop operation, and increase the amount of power generated. It becomes possible to make it.

10: Power generation system 11: MGT (micro gas turbine)
12: Generator 13: SOFC (fuel cell)
13A: Fuel pole 13B: Air pole 60, 60': Control device 105: Fuel cell cell 111: Solid electrolyte 141: Abnormality determination unit 142: Output control unit 143: Abnormality resolution determination unit 144: Abnormality cause identification unit 151: Storage unit 152: Extraction unit 153: Cause identification unit 154: Cause elimination unit 155: Display unit 215: Power generation room

Claims (13)

A fuel cell control device including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged.
Abnormality determination for determining whether or not a specific abnormality that may be resolved by increasing or decreasing the load of the fuel cell has occurred based on a plurality of measurement data related to the fuel cell taken into the control device. Department and
When the abnormality determination unit determines that the specific abnormality has occurred, the output control unit that reduces or increases the load on the fuel cell according to the cause of the specific abnormality that has occurred.
An abnormality resolution determination unit that determines whether or not the specific abnormality has been resolved by reducing or increasing the load on the fuel cell .
A storage unit that stores cause-specific information that associates information on the specific abnormality with the cause of the specific abnormality.
When the abnormality determination unit determines that the specific abnormality has occurred, an extraction unit that extracts the cause identification information corresponding to the generated specific abnormality from the storage unit, and an extraction unit.
A fuel cell control device including a cause identification unit that identifies the cause that caused the specific abnormality by using the cause identification information extracted by the extraction unit. The fuel cell control device according to claim 1, wherein the specific abnormality is an abnormality relating to an increase or decrease in the temperature of the power generation chamber. The output control unit controls to maintain the load of the fuel cell when the specific abnormality is resolved when the abnormality resolution determination unit determines that the specific abnormality has been resolved. Alternatively, the fuel cell control device according to claim 2. In the abnormality resolution determination unit, the load of the fuel cell is reduced or increased by the output control unit, and the load of the fuel cell after the decrease or increase is held for a preset predetermined period, and then the specific abnormality is determined. The fuel cell control device according to any one of claims 1 to 3, which determines whether or not the problem has been resolved. The output control unit limits the target load to a predetermined protection lower limit value or a predetermined protection upper limit value, and sets the target load by a predetermined amount until the abnormality resolution determination unit determines that the specific abnormality has been resolved. The fuel cell control device according to any one of claims 1 to 4, wherein the fuel cell is gradually lowered or raised. The output control unit lowers or raises the target load to a predetermined protection lower limit value or a predetermined protection upper limit value.
The abnormality dissolution decider may claim after the target load is held between reached office periodically to the protective lower limit value or the protection upper limit value, whether the particular abnormality is eliminated from the determination section determines 1 4. The fuel cell control device according to any one of 4. The fuel cell control device according to claim 5 or 6, wherein the protection lower limit value is set to a value larger than the load of the fuel cell in which the supply of reforming water is required. Claims 1 to 7 are such that the output control unit controls to recover the load of the fuel cell to the required load when it is determined that the specific abnormality is resolved and the specific abnormality does not recur. The fuel cell control device according to any one of. The fuel cell control device according to claim 1 , further comprising a display unit that displays the cause identified by the cause identification unit. The fuel cell control device according to claim 1 or 9 , further comprising a cause elimination unit that eliminates the cause identified by the cause identification unit. With a micro gas turbine
A fuel cell including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged.
A power generation system including the fuel cell control device according to any one of claims 1 to 10 . A method for protecting and controlling a fuel cell including a power generation chamber in which a plurality of fuel cell cells including a fuel electrode, a solid electrolyte, and an air electrode are arranged.
A step of determining whether or not a specific abnormality that may be resolved by increasing or decreasing the load of the fuel cell has occurred based on a plurality of measurement data related to the fuel cell.
A step of increasing or decreasing the load of the fuel cell according to the cause of the specific abnormality when it is determined that the specific abnormality has occurred.
By the increase or decrease of the load of the fuel cell, and determining whether the particular error is eliminated,
A step of storing cause-specific information in which information on the specific abnormality is associated with the cause of the specific abnormality, and
A step of extracting the cause identification information corresponding to the generated specific abnormality from the cause identification information when it is determined that the specific abnormality has occurred.
A method for protecting and controlling a fuel cell, which comprises a step of identifying the cause of causing the specific abnormality by using the extracted cause identification information . The fuel cell protection control method according to claim 12 , further comprising a step of maintaining the load of the fuel cell when the specific abnormality is resolved when it is determined that the specific abnormality has been resolved.

Images