JP6062263B2 - Combined power generation system operation control device, combined power generation system, and combined power generation system operation method - Google Patents

Description

  The present invention relates to a combined power generation system operation control device, a combined power generation system, and a combined power generation system operation method capable of controlling an optimal operation stop of a fuel cell.

  2. Description of the Related Art Fuel cells that generate electricity by chemically reacting fuel gas and oxygen are known. Among these, solid oxide fuel cells (hereinafter referred to as “SOFC”) use ceramics such as zirconia ceramics as an electrolyte, such as city gas, natural gas, petroleum, methanol, and coal gasification gas. Is a fuel cell operated using as a fuel.

A combined power generation system that generates power by combining a SOFC and an internal combustion engine such as a gas turbine is also known.
In Patent Document 1, in the combined power generation system, the gas supply to the combustor of the gas turbine cannot be urgently stopped when the system is shut down. Therefore, by providing a power consumption unit that consumes the power generated by the turbine generator, It is disclosed that control is performed so as to prevent the rotation and overspeed of the gas turbine from being increased.

JP 2008-293849 A

  Conventionally, the stop operation due to the occurrence of an abnormality in the SOFC has a processing step uniquely determined according to the content of the abnormality. However, in the combined power generation system, operation determination according to the state of each device is complicated, and it is desired to establish a control method for an appropriate stop operation when an abnormality occurs.

  The present invention has been made in view of such circumstances, and an operation control device for a combined power generation system and a combined power generation system capable of performing an optimal stop operation when an abnormality requiring the stop of the fuel cell occurs. And an operation method of the combined power generation system.

  In order to solve the above-described problems, the operation control apparatus, the combined power generation system, and the combined power generation system operation method of the present invention employ the following means.

  An operation control apparatus for a combined power generation system according to a first aspect of the present invention is an operation control apparatus for a combined power generation system that performs power generation by combining a fuel cell and an internal combustion engine that is operated using fuel gas discharged from the fuel cell. An abnormality detection means for detecting an abnormality of the combined power generation system, and when the abnormality detection means detects an abnormality that requires the fuel cell to stop, an abnormality state and an operation state of the combined power generation system are detected. Stop operation determining means for determining a stop operation according to the combination.

The operation control apparatus according to this configuration controls the stop of the operation of the combined power generation system that performs power generation by combining the fuel cell and the internal combustion engine that is operated using the fuel gas discharged from the fuel cell.
In this configuration, the abnormality of the combined power generation system is detected by the abnormality detection means. When an abnormality that requires stopping of the fuel cell is detected, a stop operation according to a combination of the abnormality state and the operation state of the combined power generation system is determined by the stop operation determining means.
That is, when an abnormality is detected in the combined power generation system, this configuration does not simply perform a stop operation according to the abnormality, but performs a stop operation according to the operation state of the combined power generation system when the abnormality is detected. Therefore, when an abnormality requiring stopping of the fuel cell occurs, an optimal stopping operation can be performed.

In the first aspect, the stop operation determining means performs a stop operation according to whether or not circulation is possible to return the inert gas discharged from the fuel cell to the fuel cell as the operation state as the operation state. Is preferred.

  According to this configuration, if the inert gas can be supplied, the combined power generation system can be quickly cooled by circulating the inert gas, so that a more optimal stop operation can be performed.

  In the first aspect, when the stop operation determining means is in the operation state in which inert gas cannot be circulated, as the stop operation, the supply of fuel gas to the fuel cell is stopped and the fuel gas is contained. It is preferable to stop the internal combustion engine.

  According to this configuration, a more optimal stop operation can be performed in an operation state in which the circulation of the inert gas is impossible.

  In the first aspect, when the stop operation determining means is in the operation state in which an inert gas can be supplied, as the stop operation, the supply of fuel gas to the fuel cell is stopped and the internal combustion engine is stopped. After that, the fuel cell is preferably decompressed and purged with an inert gas.

  According to this configuration, a more optimal stop operation can be performed in an operation state in which an inert gas can be supplied.

  In the first aspect, it is preferable that the operation state is whether or not the recirculation blower that circulates the gas discharged from the fuel cell to the fuel cell can be operated and whether or not the inert gas can be supplied.

  According to this configuration, it is possible to easily determine whether or not the fuel cell using the inert gas can be cooled.

  In the first aspect, it is preferable that the stop operation determining means circulates the inert gas by operating the recirculation blower in the stop operation when the recirculation blower can be operated.

  According to this configuration, the fuel cell is rapidly cooled.

  A combined power generation system according to a second aspect of the present invention includes a fuel cell, an internal combustion engine that is operated using fuel gas discharged from the fuel cell, and the operation control device described above.

The operation method of the combined power generation system according to the third aspect of the present invention is an operation method of the combined power generation system that performs power generation combining a fuel cell and an internal combustion engine operated using fuel gas discharged from the fuel cell. Then, when an abnormality detection step for detecting an abnormality of the combined power generation system and an abnormality that requires stopping of the fuel cell are detected, a stop operation corresponding to a combination of the abnormality state and the operation state of the combined power generation system is determined. seen including a stop operation determining step, a of the stop operation determining step, as the operating state, performs the stopping operation in accordance with whether the circulation returning the inert gas discharged from the fuel cell to the fuel cell.

  According to the present invention, there is an excellent effect that an optimum stopping operation can be performed when an abnormality requiring stopping of the fuel cell occurs.

1 is a configuration diagram of a combined power generation system according to an embodiment of the present invention. It is a block diagram which shows the electric constitution of the operation control apparatus which concerns on embodiment of this invention. It is a flowchart which shows the flow of the abnormal stop determination process which concerns on embodiment of this invention.

  Hereinafter, an embodiment of an operation control device for a combined power generation system, a combined power generation system, and an operation method for the combined power generation system according to the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a combined power generation system 10 according to the present embodiment.
The combined power generation system 10 generates power by combining a fuel cell and an internal combustion engine that is operated using fuel gas discharged from the fuel cell. The combined power generation system 10 is constantly monitored.

  The SOFC 12, which is a fuel cell, generates power by supplying an oxidizing gas (air in the present embodiment) to the air electrode and supplying a fuel gas to the fuel electrode. The SOFC 12 is covered with the pressure vessel 14. The SOFC 12 is provided with a pressure sensor 15A that measures the pressure in the pressure vessel 14 and a temperature sensor 15B that measures the temperature in the pressure vessel 14.

The internal combustion engine is, for example, a small gas turbine (hereinafter, referred to as a micro gas turbine, “MGT”) 16.
The MGT 16 is supplied with a compressor 18 that supplies compressed air to the air electrode of the SOFC 12, a discharge air discharged from the air electrode, and a fuel gas discharged from at least the fuel electrode, and generates a high-temperature combustion gas. A turbine 22 that is rotationally driven by the combustion gas discharged from the combustor 20 is provided.

The SOFC 12 is supplied with reducing gas (hydrogen gas in the present embodiment), water vapor, inert gas (nitrogen gas in the present embodiment), and fuel gas (city gas in the present embodiment) via the fuel supply line 24. It can be supplied. Further, flow rate adjustment valves (hereinafter referred to as “flow control valves”) 28 </ b> A to 28 </ b> D that adjust the gas flow rate corresponding to each gas are provided.
Examples of the fuel gas include liquefied natural gas (LNG), city gas (CNG), hydrocarbon gas such as hydrogen (H ₂ ) and carbon monoxide (CO), methane (CH ₄ ), and carbonaceous materials such as coal. A gas produced by a raw material gasification facility can be used. The fuel gas is preheated by the fuel preheater 26 and then supplied to the SOFC 12.

  The fuel gas discharged from the SOFC 12 is cooled by the cooler 30, supplied to the combustor 20 by the fuel recirculation line 32, and returned to the SOFC 12. The fuel recirculation line 32 includes a control valve 34 that controls the differential pressure in the SOFC 12 and a recirculation blower 36 that circulates gas discharged from the SOFC 12 to the SOFC 12.

Further, a flow control valve 38 is provided in a line for returning fuel to the SOFC 12 in the fuel recirculation line 32, and a shutoff valve 40 is provided in a line for supplying fuel to the combustor 20.
The fuel recirculation line 32 is branched, and the fuel gas can be purged by the discharge line 42. The discharge line 42 is provided with a pressure reducing valve 44. That is, the fuel gas in the combined power generation system 10 is purged when the pressure reducing valve 44 is opened.

The SOFC 12 is compressed by the compressor 18, and air preheated by the air preheater (regenerative heat exchanger) 48 is supplied via the air supply line 46. The air supply line 46 is provided with a flow control valve 50 that adjusts the flow rate of air from the compressor 18. The air supply line 46 can be supplied to the combustor 20 via the exhaust air supply line 56 without supplying a part of the air to the SOFC 12 by the branched bypass line 54. The bypass line 54 is provided with a flow control valve 58 that adjusts the flow rate of air passing through the bypass line 54.
The air exhausted from the SOFC 12 is supplied to the combustor 20 through the exhaust air supply line 56. The exhaust air supply line 56 is provided with a control valve 60 that controls the flow rate of air to be circulated.
The exhaust air supply line 56 is branched, and air can be purged by the exhaust line 62. The discharge line 62 is provided with a pressure reducing valve 64. That is, the air in the combined power generation system 10 is vented when the pressure reducing valve 64 is opened.

  FIG. 2 is a block diagram showing an electrical configuration of the operation control device 80 according to the present embodiment. The operation control device 80 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), and a computer-readable recording medium. A series of processes for realizing various functions is recorded on a recording medium or the like in the form of a program as an example, and the CPU reads the program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions are realized.

  The operation control device 80 includes an abnormality detection unit 82, a stop operation determination unit 84, and a stop instruction unit 86.

  The abnormality detection unit 82 detects an abnormality of the combined power generation system 10. Specifically, the abnormality detection unit 82 receives measurement results at a plurality of measurement points of the combined power generation system 10 (hereinafter referred to as “always monitoring data”), and detects an abnormality based on the constantly monitoring data. The constantly monitored data includes, for example, the pressure at each location, the differential pressure between the fuel electrode and the air electrode of the SOFC 12, the temperature at each location, the gas concentration at each location, the drain pot level at each location, the gas flow rate at each location, And the generated current of the SOFC 12.

  When the abnormality detection unit 82 detects an abnormality that requires the SOFC 12 to stop, the stop operation determination unit 84 determines a stop operation according to the combination of the abnormality state and the operation state of the combined power generation system 10.

  Specifically, the stop operation pattern storage unit 88 stores a stop operation pattern corresponding to the combination of the stored abnormal state and operation state. Then, the stop operation determination unit 84 reads the stop operation corresponding to the combination of the abnormal state and the operation state of the combined power generation system 10 from the stop operation pattern storage unit 88. The stop operation pattern is set to a plurality of patterns based on a trip state B, a trip state A, and a trip state A ′, which will be described in detail later. The trip state indicates a state where power generation is stopped when the combined power generation system 10 detects an abnormality.

  The stop instruction unit 86 outputs a control instruction for performing the stop operation determined by the stop operation determination unit 84 to various devices.

  FIG. 3 is a flowchart showing a flow of determination processing (hereinafter referred to as “abnormal stop determination processing”) when the combined power generation system 10 is abnormally stopped. The abnormal stop determination process is performed by the operation control device 80 together with the start of operation of the combined power generation system 10.

  First, in step 100, an input of constant monitoring data is accepted.

  In the next step 102, the state of the combined power generation system 10 (hereinafter referred to as “system state”) is confirmed based on the inputted constant monitoring data. Specifically, the value for each measurement point indicated by the constantly monitored data is compared with an allowable range that is predetermined for each measurement point.

  In the next step 104, it is determined whether or not there is a measurement point that is out of the allowable range. If the determination is affirmative, the process proceeds to step 106. If the determination is negative, the process returns to step 100. The system status check is repeated periodically.

  In step 106, it is determined whether or not the value of the measurement point that is out of the allowable range is a serious abnormality that requires the SOFC 12 to stop. If the determination is affirmative, the process proceeds to step 110, and if the determination is negative. Control goes to step 108. The transition to step 108 is a case where the abnormality is a minor abnormality that does not require the combined power generation system 10 to be stopped. In the case of a serious abnormality, the combined power generation system 10 needs to be stopped.

  In step 108, since it is a minor abnormality, an alarm is issued and the process returns to step 100. In the process, the operator confirms the minor abnormality and eliminates the minor abnormality.

In step 110, input of operation monitoring data is accepted.
The operation monitoring data is data for monitoring the operation state of the combined power generation system 10, and in this embodiment, the recirculation blower operation data indicating whether or not the recirculation blower 36 can be operated and the nitrogen gas flow for performing nitrogen venting. This is nitrogen continuous supply data indicating whether continuous supply (hereinafter referred to as “nitrogen continuous supply”) is possible.

  In step 112, the driving state is confirmed based on the driving monitoring data. The operation state according to the present embodiment is whether or not the recirculation blower 36 can be operated and whether or not nitrogen as an inert gas can be supplied. Thereby, the operation control device 80 can easily determine whether or not the SOFC 12 can be cooled using nitrogen gas.

  In step 114, it is determined whether the operation of the control device related to the operation monitoring data is normal. If the determination is affirmative, the process proceeds to step 116. If the determination is negative, the process proceeds to step 110. In this process, the control device is operated so as to operate normally, and the operation state is confirmed again based on the operation monitoring data.

In step 116, the SOFC 12 is stopped based on the system state and the operating state, and the abnormal stop determination process is terminated.
As described above, when the abnormality is detected in the combined power generation system 10, the operation control device 80 according to the present embodiment does not simply stop in accordance with the abnormality, but operates the combined power generation system 10 when the abnormality is detected. The combined power generation system 10 is stopped according to the state. Therefore, the operation control device 80 can perform an optimal stop operation of the combined power generation system 10 when an abnormality that requires the SOFC 12 to stop occurs.

  Steps 100 to 114 correspond to the function of the abnormality detection unit 82, and step 116 corresponds to the functions of the stop operation determination unit 84 and the stop instruction unit 86.

  Further, in the abnormal stop determination process described above, a mode has been described in which the occurrence of an abnormality is detected when there is a measurement point that is out of the allowable range. It is good also as a form which detects.

Next, the stop operation corresponding to the combination of the serious abnormality in the system state and the operation state will be described with reference to the examples in Tables 1 to 4.
Tables 1 to 4 display the stop operation as “A”, “A ′”, and “B” based on the trip state. In addition, the serious abnormality of the system state shown in Table 1 to Table 4 is an example. Further, whether or not the recirculation flow path can be operated in Tables 1 to 4 depends on whether or not the recirculation blower 36 can be operated.

  The trip state B is a normal stop performed on the fuel electrode side of the SOFC 12 when the combined power generation system 10 is difficult to operate but the recirculation blower 36 is operable (operation continuation difficult state). Specifically, in the trip state B, the auxiliary machine of the combined power generation system 10 is stopped, the supply of gas to the SOFC 12 is stopped, and the gas is temporarily contained, and then the MGT 16 is stopped, and the pressure vessel of the SOFC 12 The inside of the combined power generation system 10 including the inside 14 is decompressed. In the trip state B, the fuel gas is vented (purged) with nitrogen gas using the recirculation blower 36, and the supply of the nitrogen gas used for purging is stopped after the temperature is sufficiently lowered.

The trip state A is an emergency stop performed on the fuel electrode side of the SOFC 12 when the combined power generation system 10 cannot be operated (operation disabled state). Specifically, in the trip state A, the auxiliary machine of the combined power generation system 10 is stopped, the gas supply to the SOFC 12 is stopped and the gas is temporarily contained, and then the MGT 16 is stopped, and the pressure vessel of the SOFC 12 The inside of the combined power generation system 10 including the inside 14 is decompressed. In the trip state A, the fuel gas is vented (purged) with nitrogen gas without using the recirculation blower 36, and the supply of the nitrogen gas used for purging is stopped after the temperature is sufficiently lowered.
As described above, the trip state B and the trip state A are selected based on the difference in whether or not the recirculation blower 36 can be operated. In the trip state B, the recirculation blower 36 can be used to purge with less nitrogen gas than in the trip state A.

  The trip state A ′ is a state in which the operation is not possible, and when the continuous supply of nitrogen is impossible together with the operation of the recirculation blower 36, that is, when purging with nitrogen gas is impossible and the urgency is higher than the emergency stop, the SOFC 12 This is an emergency stop performed on the fuel electrode side. Specifically, in the trip state A ′, after stopping the auxiliary machine of the combined power generation system 10 and stopping the supply of gas to the SOFC 12, the MGT 16 is stopped and the gas is kept sealed. To do.

  As described above, the trip state B, trip state A, and trip state A ′ are selected based on whether or not the nitrogen gas that is an inert gas can be circulated, that is, whether or not the recirculation blower 36 can be operated and whether nitrogen is continuously supplied. Based on whether or not. This is because the combined power generation system 10 can be cooled by circulating the nitrogen gas in an operating state in which the nitrogen gas can be circulated. In particular, in the trip state B, since the nitrogen gas is circulated using the recirculation blower 36, the fuel electrode side of the SOFC 12 is rapidly cooled.

Table 1 shows a case where the cause of the abnormality is an abnormality of the MGT 16 and the detected abnormality is subdivided into an abnormality of the MGT control panel, an abnormality of the air temperature at the inlet of the combustor 20, and an abnormality of the original pressure of the compressor 18. It is an example.
An abnormality in the MGT control panel and an abnormality in the air temperature at the inlet of the combustor 20 have a significant effect on other devices. Therefore, even if the recirculation blower 36 can be operated and nitrogen can be continuously supplied, the trip state A The stop operation is performed by.
In addition, when “-” is displayed in Tables 1 to 4, a combination with a factor that is not directly related to the SOFC 12 other than the operation state such as whether the recirculation flow path is operable or whether nitrogen is continuously supplied as the operation state is selected. Items that are judged in consideration are collectively indicated as “-”, and do not indicate that the stop operation is not performed. The explanation is omitted so as not to confuse the judgment state of the trip state due to the increase in the number of examples of the driving state.
For example, in Table 1, the MGT control panel abnormality is monitored as the system state, and in the determination when the nitrogen supply is not possible as the operation state, the operation state not displayed is MGT16 operation availability. When the operation is stopped, air cannot be supplied, so that the trip state A ′ is stopped. In addition, as a case where there are a plurality of causes of the abnormality, for example, those caused by a combination of a control abnormality (see Table 3) and a power failure or a raw material abnormality (see Table 4) of the combined power generation system 10 are shown in Table 3 and Table 4. Judgment corresponding to the combination of abnormal causes is performed, and the trip state A ′ stop operation is performed.

Table 2 shows the case where the cause of the abnormality is an abnormality of the SOFC 12, and the detected abnormality is an abnormality of the air inlet / outlet temperature of the SOFC 12, an abnormality of the air flow rate, an abnormality of the fuel inlet / outlet temperature, an abnormality of the fuel flow rate / concentration. It is an example that is subdivided into abnormal pressure, and abnormal voltage.

Table 3 shows the case where the cause of the abnormality is a control abnormality. The detected abnormality cannot be controlled by the control valves 34 and 60, and the control device (for example, Distributed Control System: DCS) of the combined power generation system 10 cannot be controlled. This is an example of subdivided. When the control by the control device is disabled, it is an abnormality that makes it impossible to control parameters that lead to the failure of the SOFC 12, such as the temperature and pressure between the SOFC 12 and the MGT 16, and therefore the stop based on the trip state A ′ is performed.

Table 4 shows the case where the cause of the abnormality is a power failure or an abnormal supply of raw materials.
When a power failure occurs, the control device maintains an operating state with a backup power source. On the other hand, the auxiliary machines such as the recirculation blower 36 and the control valves 34 and 60 are cut off from power supply and stopped. Therefore, when a power failure occurs, the control device detects the stop of the power supply in the distribution board, and the stop operation in the trip state A ′ is performed as an optimal stop operation in a state where the recirculation blower 36 cannot be used. Note that a power failure includes a manual emergency stop.
The supply abnormality of the raw material is that supply of main raw materials such as hydrogen gas, air, and nitrogen gas is interrupted. Since the material supply abnormality has a significant effect on each apparatus, a stop operation is performed in the trip state A ′.

Next, the stop operation for each abnormality in the system state will be described in detail.
In the example described above, the abnormality of the MGT 16 is an abnormality of the MGT control panel, an abnormality of the air temperature at the inlet of the combustor 20, and an abnormality of the original pressure of the compressor 18.
When the SOFC 12 and MGT 16 are operated in a combined cycle, an abnormality in one of the SOFC 12 and MGT 16 may cause a serious failure in the other apparatus, so a stop operation is required based on a rapid abnormality detection. To do.

  An abnormality of the MGT control panel is detected when, for example, an alarm for the MGT 16 or an emergency stop of the MGT 16 is detected. When an abnormality of the MGT control panel is detected and nitrogen continuous supply is possible, a stop operation by the trip state A is performed.

  An abnormality in the air temperature at the inlet of the combustor 20 is detected when air of a predetermined value (for example, 650 ° C.) or more is supplied. When an abnormality in the air temperature at the inlet of the combustor 20 is detected and nitrogen continuous supply is possible, a stop operation in the trip state A is performed.

  An abnormality in the original pressure of the compressor 18 is detected when the specified pressure value in the steady state derived from the air intake temperature of the MGT 16 and the detected value deviate by a predetermined value or more. When an abnormality in the original pressure of the compressor 18 is detected and nitrogen continuous supply is possible, a stop operation by the trip state B is performed.

  In addition, when abnormality of MGT16 is detected and nitrogen continuous supply is impossible, the stop operation by trip state A 'is performed.

  Further, in the above-described example, the SOFC 12 abnormality may be the SOFC 12 air inlet / outlet temperature abnormality, the air flow rate abnormality, the fuel inlet / outlet temperature abnormality, the fuel flow rate / concentration abnormality, the pressure abnormality, and the voltage abnormality. It is said.

  An abnormality is detected when the air inlet temperature or the air outlet temperature of the SOFC 12 is higher than a predetermined value (for example, 750 ° C.). The predetermined value is preferably set to a temperature that exceeds the endurance temperature of the metal member used in the SOFC 12. Then, it is preferable that the stop operation is performed when detection of the predetermined temperature that is abnormal is continued for a predetermined time (for example, 3 seconds). When the nitrogen supply is possible as the operation state, the stop operation by the trip state B is performed, and when the nitrogen supply is not possible, the stop operation by the trip state A 'is performed.

  Also, in the SOFC 12, when the air flow rate abnormality, fuel inlet / outlet temperature abnormality, fuel flow rate / concentration abnormality, pressure abnormality, and voltage abnormality exceed a predetermined value corresponding to each of them for a predetermined time In addition, it is preferable that a stop operation is performed. In this case as well, when nitrogen continuous supply is possible as the operating state, a stop operation by trip state B is performed, and when nitrogen continuous supply is not possible, a stop operation by trip state A 'is performed.

In the above-described example, the control abnormality is made impossible to control the control valves 34 and 60 and the control device.
When the control valves 34, 60, etc. are uncontrollable and can be continuously supplied with nitrogen, the stop operation by the trip state A is performed.

  More specifically, the stop operation in the trip state A when the control valves 34, 60, etc. cannot be controlled and nitrogen continuous supply is possible will be described.

  First, the operation control device 80 stops the combined operation by disconnecting the combined power generation system 10 and the power system, stopping the MGT 16, stopping city gas, and purging nitrogen. Thereafter, the operation control device 80 starts up the steam line while reducing the pressure of the SOFC 12, and supplies city gas and steam to the SOFC 12, thereby generating hydrogen gas as a reducing gas by the internal reforming reaction of the SOFC 12. However, the temperature of the power generation chamber of the SOFC 12 is lowered by an endothermic endothermic reaction and heat removal by gas circulation.

  Then, for example, after the power generation chamber reaches 700 ° C. in the container temperature in 4 hours, nitrogen gas is supplied to the fuel supply line 24, and after the temperature further decreases to 400 ° C., the supply of city gas and steam is stopped. Then, hydrogen gas is supplied. Further, after the temperature reaches 100 ° C., the gas supply is stopped, the pressure reducing valves 44 and 64 provided in the discharge lines 42 and 62 are opened, and the fuel supply line 24 and the air supply line 46 are opened to the atmosphere. . Since the combined operation is stopped by detecting an abnormality, the compressed air from the MGT 16 bypasses the SOFC 12 and is directly supplied to the combustor 20.

Further, the pressure reducing valve 44 is controlled so that the differential pressure between the fuel electrode side and the air electrode side of the SOFC 12 becomes a predetermined value (for example, 0.5 kPa). This is because the differential pressure becomes too large to prevent damage to the constituent layers in the SOFC 12. Then, city gas, water vapor, or hydrogen gas is supplied to the fuel supply line 24, and the atmosphere is opened while air is supplied to the air supply line 46, so that oxygen components are not mixed into the fuel electrode side. The power generation chamber is cooled while the stop operation is performed in a state where the pressure on the pole side is kept higher than that on the air electrode side.
In this way, in the trip state A when the control valves 34, 60, etc. are uncontrollable and can be continuously supplied with nitrogen, the flow rates of city gas, steam, and hydrogen gas are controlled according to the temperature in the power generation chamber of the SOFC 12. Then, the SOFC 12 is stopped more safely.

  When the control valves 34, 60, etc. are not controllable and cannot be continuously supplied with nitrogen, a stop operation by the trip state A 'is performed.

On the other hand, when the control device becomes uncontrollable, parameters required for stopping the SOFC 12 such as an air vent, a temperature drop and a pressure drop between the SOFC 12 and the MGT 16 cannot be controlled, and a quicker stop operation is performed. It is preferable.
In this case, the operation control device 80 stops the recirculation blower 36 and performs a stop operation based on the trip state A ′.
In the stop operation in the trip state A ′, the gas flow through the SOFC 12 is shut off and the gas is not released, so that the power generation chamber is held at the temperature and pressure during rated operation. In the power generation chamber during the rated operation, the differential pressure control between the fuel electrode and the air electrode is performed. However, since the gas is neither vented nor released in the trip state A ′, this differential pressure is maintained.

  Moreover, in order to improve the reliability of the stop operation, the power generation chamber may be cooled by an external cooling means. Examples of the external cooling means include water cooling, air cooling, and water spray. In addition, since it is cooling at the time of a power failure or control failure of the control apparatus, cooling which does not require power is preferable. As a specific example of cooling that does not require power, there is a means of causing water to flow or spray using gas (air, nitrogen, etc.) stored in a container, for example.

The cooling when the trip state A ′ is performed will be described in detail.
When venting with air is impossible, the combined operation is canceled, the air on the air electrode side of the SOFC 12 is contained, and supply and discharge of new air are shut off. In this case, after the safety of the fuel supply line 24 is confirmed, the recirculation blower 36 is restarted, and while supplying nitrogen gas as an inert gas, the fuel recirculation line 32 (fuel exhaust air supply line) is used. By performing ventilation, the fuel electrode may be cooled while maintaining the differential pressure.
When nitrogen gas cannot be vented, the fuel supply line 24 and the discharge line 42 are closed, and the supply and discharge of gas on the fuel electrode side of the SOFC 12 are shut off. In such a case, it is preferable that the power generation chamber is cooled by the external cooling means as described above.

As described above, the operation control device 80 according to the present embodiment controls the stop of the operation of the combined power generation system 10 that generates power by combining the SOFC 12 and the MGT 16 that is operated using the fuel gas discharged from the SOFC 12. . Then, the operation control device 80 detects the abnormality of the combined power generation system 10, and when the abnormality detection unit 82 detects an abnormality that requires the SOFC 12 to stop, A stop operation determining unit 84 that determines a stop operation according to the combination of operation states.
Therefore, when an abnormality is detected in the combined power generation system 10, the operation control device 80 does not simply perform a stop operation according to the abnormality, but according to the operation state of the combined power generation system 10 when the abnormality is detected. Since the stop operation is performed, an optimal stop operation can be performed when an abnormality requiring the SOFC 12 to stop occurs.
In this way, the operation control device 80 can perform a stop operation for protecting the SOFC 12 by performing an optimal stop operation based on the detected abnormal state when an abnormality that requires the SOFC 12 to stop occurs. It becomes.

  As mentioned above, although this invention was demonstrated using said each embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various changes or improvements can be added to the above-described embodiments without departing from the gist of the invention, and embodiments to which the changes or improvements are added are also included in the technical scope of the present invention.

  The flow of the abnormal stop determination process described in each of the above embodiments is also an example, and unnecessary steps are deleted, new steps are added, or the processing order is changed within a range not departing from the gist of the present invention. Or you may.

10 Combined power generation system 12 SOFC
16 MGT
36 Recirculation blower 80 Operation control device 82 Abnormality detection unit 84 Stop operation determination unit

Claims (7)

An operation control device for a combined power generation system that performs power generation combining a fuel cell and an internal combustion engine that is operated using fuel gas discharged from the fuel cell,
An abnormality detecting means for detecting an abnormality of the combined power generation system;
When the abnormality detection unit detects an abnormality that requires the fuel cell to stop, a stop operation determination unit that determines a stop operation according to a combination of the abnormality state and the operation state of the combined power generation system;
Equipped with a,
The operation control device of the combined power generation system, wherein the stop operation determining means performs a stop operation according to whether or not circulation of returning the inert gas discharged from the fuel cell to the fuel cell as the operation state is performed . In the operation state in which the inert gas cannot be circulated, the stop operation determining means includes, as the stop operation, the supply of the fuel gas to the fuel cell and the containment of the fuel gas, and the stop of the internal combustion engine. operation control device for a hybrid power system of claim 1 wherein performing. The stop operation determining means stops the supply of the fuel gas to the fuel cell as the stop operation and stops the fuel cell after stopping the internal combustion engine in the operation state in which an inert gas can be supplied. The operation control device of the combined power generation system according to claim 1 or 2 , wherein the pressure is reduced and purging with an inert gas is performed. The operating conditions, any one of claims 3 to gas discharged from the fuel cell whether the operation of the recirculation blower for circulating to the fuel cell, and from the claims 1 a possibility of the supply of inert gas The combined power generation system operation control device described. 5. The operation control apparatus for a combined power generation system according to claim 4 , wherein when the recirculation blower is operable, the stop operation determining means circulates the inert gas by operating the recirculation blower in the stop operation. A fuel cell;
An internal combustion engine operated using fuel gas discharged from the fuel cell;
The operation control device according to any one of claims 1 to 5 ,
A combined power generation system comprising: An operation method of a combined power generation system for generating power by combining a fuel cell and an internal combustion engine operated using fuel gas discharged from the fuel cell,
An abnormality detection step of detecting an abnormality of the combined power generation system;
When detecting an abnormality that requires stopping of the fuel cell, a stop operation determining step of determining a stop operation according to a combination of the abnormal state and the operation state of the combined power generation system;
Only including,
The operation method of the combined power generation system, wherein the stop operation determining step performs a stop operation according to whether or not circulation of returning the inert gas discharged from the fuel cell to the fuel cell as the operation state is performed .

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