Abnormality diagnosis system

Abstract

To provide an abnormality diagnosis system that can diagnose the cause of operational abnormalities in raw fuel blowers.SOLUTION: In an abnormality diagnosis system, a fuel cell device is equipped with an electrical conductivity meter that measures the electrical conductivity of recovered water at a predetermined location in the water utilization system, and when a raw fuel abnormality condition is met in which the output of the raw fuel blower is greater than the standard output corresponding to the target raw fuel flow rate by a predetermined value or more, the abnormality diagnosis system continues the stopped state for a second stop period that is longer than the first stop period in the subsequent shutdown process, and when the electrical conductivity measured by the electrical conductivity meter after the stopped state has continued for the second stop period meets the predetermined recovered water abnormality condition, the abnormality diagnosis system determines that hot water is flowing into the exhaust gas flow path in the exhaust heat recovery heat exchanger.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an abnormality diagnosis system. [Background technology]

[0002] Patent Document 1 (JP 2019-71703 A) describes a system including multiple fuel cell systems and a management device communicatively connected to the multiple fuel cell systems. The management device acquires, from at least one of the multiple fuel cell systems, degradation information for the cell components constituting the fuel cell system. The management device then detects a detected deteriorated component determined to be deteriorated based on the degradation information, identifies multiple cell components corresponding to the manufacturing lot number of the detected deteriorated component as multiple deteriorated components, and shuts down a group of deteriorated fuel cell systems, which are a group of fuel cell systems each equipped with the multiple deteriorated components, based on the degradation information for the detected deteriorated component.

[0003] In this way, the system described in Patent Document 1 attempts to use the degradation information of one fuel cell system to determine whether or not the cell components of other fuel cell systems have deteriorated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-71703 Summary of the Invention [Problem to be solved by the invention]

[0005] There are various types of abnormalities that can occur in a fuel cell system. For example, a fuel cell system as shown in Fig. 2 includes a reformer that generates fuel gas by steam reforming raw fuel, a cell stack having a plurality of fuel cell units each having an anode to which the fuel gas generated in the reformer is supplied and a cathode to which air is supplied, a raw fuel supply path through which the raw fuel supplied to the reformer flows, a raw fuel blower that supplies the raw fuel to the reformer via the raw fuel supply path, an air supply path through which air supplied to the cathode flows, an air blower that supplies air to the cathode via the air supply path, a combustion unit that burns offgas discharged from the cell stack, and an exhaust gas supply pipe through which exhaust gas including combustion exhaust gas generated in the combustion unit flows. the hot water circulation section configured to supply hot water extracted from the hot water storage tank to the heat exchanger for exhaust heat recovery and return the hot water that has flowed through the heat exchanger for exhaust heat recovery to the hot water storage tank by circulating the hot water so that the heat of the exhaust gas is recovered in the heat exchanger for exhaust heat recovery; and a water utilization system having a recovered water tank for storing recovered water that can be recovered from the exhaust gas by cooling the exhaust gas in the heat exchanger for exhaust heat recovery, and supplying the recovered water stored in the recovered water tank for steam reforming of raw fuel in the reformer.

[0006] In such a heat exchanger for exhaust heat recovery in a fuel cell system, the output of the raw fuel blower is adjusted so that the raw fuel flow rate measured by the raw fuel flow rate measuring device becomes the target raw fuel flow rate. If there are no abnormalities, the output of the raw fuel blower becomes close to the standard output corresponding to the target raw fuel flow rate.

[0007] However, if some abnormality occurs, the raw fuel blower may operate abnormally, for example, the output of the raw fuel blower may become greater than the standard output corresponding to the target raw fuel flow rate by a predetermined value or more.

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an abnormality diagnosis system that can diagnose the cause of an operational abnormality in a raw fuel blower. [Means for solving the problem]

[0009] A characteristic configuration of an abnormality diagnosis system according to the present invention for achieving the above object is an abnormality diagnosis system comprising a fuel cell device installed in a facility, and an abnormality diagnosis device that diagnoses the details of an abnormality occurring in the fuel cell device based on information received from the fuel cell device via an information communication line, The fuel cell device includes a reformer that generates fuel gas by steam reforming a raw fuel, a cell stack having a plurality of fuel cell units each having an anode to which the fuel gas generated in the reformer is supplied and a cathode to which air is supplied, a raw fuel supply path through which the raw fuel supplied to the reformer flows, a raw fuel blower that supplies the raw fuel to the reformer via the raw fuel supply path, an air supply path through which air supplied to the cathode flows, an air blower that supplies air to the cathode via the air supply path, a combustion unit that combusts off-gas discharged from the cell stack, an exhaust gas flow path through which exhaust gas containing gas generated by combustion in the combustion unit flows, a hot water storage tank that stores hot water that has recovered heat from the exhaust gas, a heat exchanger for exhaust heat recovery provided midway through the exhaust gas flow path, and a hot water circulation unit configured to supply the hot water taken out of the hot water tank to the heat exchanger for exhaust heat recovery and return the hot water that has flowed through the heat exchanger for exhaust heat recovery to the hot water storage tank, thereby circulating the hot water so that the heat of the exhaust gas is recovered in the heat exchanger for exhaust heat recovery in the hot water storage tank; a water utilization system having a recovered water tank for storing recovered water that can be recovered from the exhaust gas by cooling the exhaust gas in the heat exchanger for exhaust heat recovery, and supplying the recovered water stored in the recovered water tank for steam reforming of the raw fuel in the reformer; a control device; a raw fuel flow rate measuring device for measuring the flow rate per unit time of the raw fuel supplied to the reformer via the raw fuel supply path; and an electrical conductivity measuring device for measuring the electrical conductivity of the recovered water at a predetermined location in the water utilization system; the control device of the fuel cell device is configured to adjust the output of the raw fuel blower so that the raw fuel flow rate measured by the raw fuel flow rate measuring device becomes a target raw fuel flow rate, and when a predetermined stop condition is satisfied, to perform a stop process of stopping the supply of the raw fuel to the reformer and continuing a stop state in which power generation in the fuel cell is stopped for a first stop period; The abnormality diagnosis device is characterized in that when a raw fuel abnormality condition is met, in which the output of the raw fuel blower is greater than the standard output corresponding to the target raw fuel flow rate by a predetermined value or more, in the subsequent shutdown process, the shutdown state is continued for a second shutdown period that is longer than the first shutdown period, and if the electrical conductivity measured by the electrical conductivity measuring device after the shutdown state has continued for the second shutdown period meets a predetermined recovered water abnormality condition, it determines that the hot water is flowing into the exhaust gas flow path in the exhaust heat recovery heat exchanger.

[0010] If an abnormality occurs in the exhaust heat recovery heat exchanger and hot water flows into the exhaust gas flow path in the exhaust heat recovery heat exchanger, impurities contained in the hot water also flow into the water utilization system, and the water containing the impurities is supplied to the reformer for steam reforming. The impurities may then precipitate in the reformer or in a stage preceding the reformer, causing a large pressure drop in that area. Therefore, in this characteristic configuration, if a raw fuel abnormality condition is met, in which the output of the raw fuel blower is greater than the standard output corresponding to the target raw fuel flow rate by a predetermined value or more, the abnormality diagnosis device continues the stopped state for a second stop period, which is longer than the first stop period, during the subsequent shutdown process. In other words, if hot and cold water is flowing into the water utilization system in the exhaust heat recovery heat exchanger as described above, extending the shutdown process from the first stop period to the second stop period is likely to increase the total amount of impurities flowing into the water utilization system during that shutdown period. This is likely to increase the electrical conductivity of the recovered water measured by the electrical conductivity meter. Therefore, if the electrical conductivity measured by the electrical conductivity meter after the shutdown state has continued for the second stop period meets the predetermined recovered water abnormality condition, the abnormality diagnosis device can determine that hot and cold water is flowing into the exhaust gas flow path in the exhaust heat recovery heat exchanger. Therefore, it is possible to provide an abnormality diagnosis system that can diagnose the cause of an operational abnormality in a raw fuel blower.

[0011] Another characteristic configuration of the abnormality diagnosis system of the present invention is that the abnormality diagnosis device determines that the recovered water abnormality condition is met if the electrical conductivity measured by the electrical conductivity measuring instrument is equal to or greater than a set value after the stopped state has continued for the second stop period.

[0012] According to the above characteristic configuration, the abnormality diagnostic device can determine that the recovered water abnormality condition is satisfied when the electrical conductivity of the recovered water after the stopped state has continued for the second stop period is equal to or higher than the set value.

[0013] Another characteristic configuration of the abnormality diagnosis system of the present invention is that the abnormality diagnosis device determines that the recovered water abnormality condition is satisfied if the electrical conductivity measured by the electrical conductivity meter after the stopped state has continued for the second stop period is equal to or greater than a set value, or if the electrical conductivity measured by the electrical conductivity meter after the stopped state has continued for the second stop period is greater by a predetermined value or more than the electrical conductivity measured by the electrical conductivity meter after the stopped state has continued for the first stop period.

[0014] According to the above characteristic configuration, the abnormality diagnosis device can determine that the recovered water abnormality condition is met if the electrical conductivity of the recovered water after the stopped state has continued for the second stop period is equal to or greater than a set value, or if the electrical conductivity of the recovered water after the stopped state has continued for the second stop period is greater than the electrical conductivity of the recovered water after the stopped state has continued for the first stop period by a predetermined value or more. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating a configuration of an abnormality diagnosis system including an abnormality diagnosis device. [Figure 2] FIG. 1 is a diagram showing the configuration of a fuel cell device. [Figure 3] 10 is a flowchart illustrating an example of an abnormality diagnosis process. DETAILED DESCRIPTION OF THE INVENTION

[0016] An abnormality diagnosis system according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of an abnormality diagnosis system including an abnormality diagnosis device 4. As shown in the figure, a fuel cell device 10 is installed in a facility 1, such as a residence or a business. The facility 1 also includes an electricity consumption device 5, a gas consumption device 6, and a Home Energy Management System (HEMS) 7. The HEMS 7 controls the operation of control target devices such as the electricity consumption device 5, the fuel cell device 10, and the gas consumption device 6. The HEMS 7 communicates with the control target devices via communication lines to receive information from each device and transmit information to each device. The HEMS 7 can also transmit information received from each device to the abnormality diagnosis device 4 and the like via an information communication line 2. The operation of the fuel cell device 10 is controlled by a fuel cell control unit 49, as described below. As described above, the abnormality diagnosis system includes the fuel cell device 10 installed in the facility 1 and the abnormality diagnosis device 4 that diagnoses the nature of an abnormality occurring in the fuel cell device 10 based on information received from the fuel cell device 10 via the information communication line 2.

[0017] The power consumption device 5 and the fuel cell device 10 are connected to a power line 8 that is connected to the power grid, and can receive power from the power grid. Power generated by the fuel cell device 10 can also be supplied to the power grid via the power line 8. The gas consumption device 6 and the fuel cell device 10 can receive gas, such as city gas, supplied from a gas supply pipe 9. Although two facilities 1 are depicted in FIG. 1, the number can be changed as appropriate. The gas, such as city gas, supplied from the gas supply pipe 9 corresponds to the "raw fuel" of the present invention, and may also be referred to as the raw fuel in the following description.

[0018] The fuel cell device 10 can access the information and communication line 2 either via the HEMS 7 or without the HEMS 7. The fuel cell device 10 can communicate information with the abnormality diagnosis device 4, the information providing server device 3, the maintenance staff terminal device 60, the manufacturing staff terminal device 61, the manager terminal device 62, and the like, which are connected to the information and communication line 2.

[0019] 2 is a diagram showing the configuration of the fuel cell device 10. The fuel cell device 10 comprises a hot module 13 having an outer container 11 and an inner container 12 provided in an inner space 48 inside the outer container 11. The fuel cell device 10 comprises various components inside the outer container 11. Below, the configuration of the fuel cell device 10 will be explained by dividing it into the hot module 13, a raw fuel supply system, an air supply system, a reflux gas supply system, a water utilization system (water recovery system, reforming water supply system), and an exhaust heat recovery system.

[0020] [Hot Module 13] A hot module 13 is provided inside the outer vessel 11, accommodating devices such as a cell stack 18 that operate in a high-temperature environment. Specifically, the hot module 13 includes a vaporizer 14, a reformer 15, a manifold 16, and a cell stack 18 in an inner space 47 inside the inner vessel 12. The vaporizer 14 vaporizes the reforming water that is supplied. The reformer 15 steam reforms the raw fuel using steam supplied from the vaporizer 14 to generate fuel gas containing hydrogen.

[0021] The cell stack 18 has a plurality of fuel cell units 17 that generate electricity using fuel gas supplied from the reformer 15 via a fuel gas supply path L2. For example, the fuel gas generated in the reformer 15 passes through the fuel gas supply path L2 and reaches the manifold 16, where the fuel gas is distributed to each of the fuel cell units 17.

[0022] The space above the cell stack 18 serves as a combustion section 19 that combusts the off-gas discharged from the cell stack 18. The heat of this combustion is transferred to the vaporizer 14 and reformer 15 above it. An igniter 20 ignites the off-gas.

[0023] The inner container 12 included in the hot module 13 is provided with an air inlet 21 used to supply air from the outside to the internal space 47 inside, and an exhaust port 22 used to exhaust air from the internal space 47 to the outside. Specifically, an air supply path L10 is connected to the air inlet 21 of the hot module 13, and air is supplied to the inside of the hot module 13. Gas present inside the hot module 13 is exhausted to the outside of the hot module 13 from the exhaust port 22 of the hot module 13. The exhaust port 22 is provided with a combustion catalyst unit 23 that catalytically combusts hydrogen, carbon monoxide, etc. contained in the exhaust gas (exhaust gas) using oxygen.

[0024] The exhaust gas that has passed through the combustion catalyst section 23 is supplied to the exhaust heat recovery heat exchanger 34. In the exhaust heat recovery heat exchanger 34, the exhaust gas, which is discharged to the outside of the inner container 12 and contains gas generated by combustion in the combustion section 19, is heat exchanged with hot water as a heat medium, which will be described later, i.e., the exhaust gas is cooled, and the moisture contained in the exhaust gas is condensed.

[0025] The fuel cell device 10 includes an exhaust gas flow path L4 through which exhaust gas flows after heat exchange with hot water in the exhaust heat recovery heat exchanger 34, a gas-liquid separation unit 35 that separates condensed water contained in the exhaust gas after heat exchange with hot water in the exhaust heat recovery heat exchanger 34, a water recovery path L5 through which the condensed water separated by the gas-liquid separation unit 35 flows, and a water purifier 37 that removes impurities contained in the condensed water recovered by the water recovery path L5. Specifically, the gas-liquid separation unit 35 is provided downstream of the exhaust heat recovery heat exchanger 34. Gas-phase components in the exhaust gas are discharged to the outside of the outer container 11 through the exhaust gas flow path L4, and liquid-phase components in the exhaust gas are supplied to the water purifier 37 through the water recovery path L5.

[0026] The fuel cell device 10 is provided with an air intake port 66, which is provided in the outer container 11, for taking in air from the outside into the outer container space 48 inside the outer container 11, and an air exhaust port 67, which is provided in the outer container 11, for exhausting air from the outer container space 48 to the outside. In addition, the fuel cell device 10 is provided with a ventilation fan 59 that ventilates the air in the outer container space 48 via the air intake port 66 and the air exhaust port 67.

[0027] When ventilation fan 59 is operating normally, the deviation of the actual rotation speed from the target rotation speed of ventilation fan 59 is less than the set value. In other words, when the deviation of the actual rotation speed from the predetermined target rotation speed of ventilation fan 59 is equal to or greater than the set value, there is a high possibility that an abnormality has occurred in ventilation fan 59.

[0028] [Raw and fuel supply system] The raw fuel supply system is a system that supplies raw fuel to the reformer 15 via a raw fuel supply path L1. Specifically, the raw fuel supply system includes a shutoff valve 26, a pressure measuring device 27, a raw fuel flow rate measuring device 28, a zero governor 29, a raw fuel blower 30, and a desulfurizer 31. In the raw fuel supply path L1, raw fuel that is supplied to the reformer 15 from outside the inner space 47 flows.

[0029] The shutoff valve 26 is switched between a state allowing or blocking the flow of raw fuel into the raw fuel supply line L1. The pressure measuring device 27 measures the pressure of the raw fuel flowing into the raw fuel supply line L1. The raw fuel blower 30 supplies the raw fuel to the reformer 15 via the raw fuel supply line L1. Specifically, the raw fuel blower 30 adjusts the flow rate per unit time of the raw fuel supplied to the reformer 15. The raw fuel flow rate measuring device 28 measures the flow rate per unit time of the raw fuel supplied to the reformer 15 via the raw fuel supply line L1. For example, the raw fuel blower 30 increases or decreases its output, such as the duty ratio of the PWM control of the raw fuel blower 30, so that the flow rate of the raw fuel measured by the raw fuel flow rate measuring device 28 becomes the target raw fuel flow rate. The fuel cell control unit 49 can also obtain information on the rotation speed of the raw fuel blower 30 at that time. The zero governor 29 adjusts the pressure of the raw fuel flowing through the raw fuel supply line L1 to the same as atmospheric pressure. The desulfurizer 31 removes sulfur compounds and the like contained in the raw fuel.

[0030] When the raw fuel blower 30 is supplying raw fuel normally, the correlation between the output of the raw fuel blower 30 and its rotational speed deviates by less than a reference value. For example, if a standard rotational speed (200 rpm) or a standard measurement value of the raw fuel flow rate measuring device 28 is determined for each output of the raw fuel blower 30 (e.g., 30%), if the raw fuel blower 30 is supplying raw fuel normally, the actual rotational speed will deviate from the standard rotational speed by less than the reference value (e.g., less than ±30%), and the actual measurement value of the raw fuel flow rate measuring device 28 will deviate from the standard measurement value by less than the reference value (e.g., less than ±30%). Furthermore, when the raw fuel blower 30 is supplying raw fuel normally, the output of the raw fuel blower 30 will deviate from the standard output determined according to the target raw fuel flow rate by less than the reference value.

[0031] [Air supply system] The air supply system supplies air to the hot module 13 via the air supply path L10. Air supplied from outside the inner container 12 to the air inlet 21 flows through the air supply path L10. The air blower 41 supplies air to the internal space 47 of the inner container 12 via the air supply path L10 and the air inlet 21. Specifically, the air blower 41 adjusts the flow rate per unit time of air supplied to the interior of the inner container 12. The air flow meter 42 measures the flow rate per unit time of air supplied to the internal space 47 of the inner container 12 by the air blower 41. For example, the air blower 41 increases or decreases the output of the air blower 41, for example, the duty ratio of the PWM control of the air blower 41, so that the air flow rate measured by the air flow meter 42 becomes a target air flow rate. The fuel cell control unit 49 can also obtain information on the rotation speed of the air blower 41 at that time. The foreign matter removing filter 40 removes (captures) foreign matter contained in the air supplied to the inner container 12 by the air blower 41.

[0032] When the air blower 41 is supplying air normally, the correlation between the output of the air blower 41 and its rotational speed deviates only by less than the reference value. Furthermore, when the air blower 41 is supplying air normally, the correlation between the output of the air blower 41 and the measurement value of the air flow measuring device 42 deviates only by less than the reference value. For example, if a standard rotational speed (200 rpm) or a standard measurement value of the air flow measuring device 42 is determined for each output of the air blower 41 (e.g., 30%), when the air blower 41 is supplying air normally, the actual rotational speed deviates only by less than the reference value (e.g., less than ±30%) from the standard rotational speed, and the actual measurement value of the air flow measuring device 42 deviates only by less than the reference value (e.g., less than ±30%) from the standard measurement value. Furthermore, when the air blower 41 is supplying air normally, the deviation of the measurement value (air flow rate) of the air flow measuring device 42 from a predetermined target air flow rate will not exceed the set value. Furthermore, when the air flow measurement by the air flow measuring instrument 42 is performed normally, the correlation between the output of the air blower 41 and the air flow measured by the air flow measuring instrument 42 will not deviate by more than the reference value.

[0033] [Reflux gas supply system] The reflux gas supply system supplies a portion of the fuel gas generated in the reformer 15 to the raw fuel supply path L1 via the reflux gas supply path L3. The reflux gas supply path L3 branches off from a branch point 24 in the fuel gas supply path L2 and merges with a junction point 25 in the raw fuel supply path L1 upstream of the desulfurizer 31. The reflux gas supply path L3 supplies a portion of the fuel gas flowing through the fuel gas supply path L2 to the raw fuel supply path L1. This allows hydrogen to be supplied to the desulfurizer 31. The reflux gas supply path L3 extends from the inside to the outside of the hot module 13. An orifice 33 is provided in the reflux gas supply path L3 and adjusts the flow rate per unit time of the fuel gas flowing through the reflux gas supply path L3. A temperature control member 32 is provided around at least a portion of the reflux gas supply path L3 to maintain the temperature of the reformed gas flowing through the reflux gas supply path L3. The condensed water recovery device 36 recovers condensed water generated in the recirculation gas supply line L3.

[0034] [Water recovery system] The water recovery system is a system that recovers water generated in the fuel cell device 10. The condensed water recovered using the water recovery line L5 is supplied to the reforming water tank 38. In the example shown, the water recovery line L5 has a first recovery line L5a that recovers water from the gas-liquid separator 35 and a second recovery line L5b that recovers water from the condensed water recovery unit 36. The condensed water recovered by the first recovery line L5a and the second recovery line L5b is supplied to the reforming water tank 38 via the water purifier 37. That is, the reforming water tank 38 stores the water from which impurities have been removed by the water purifier 37 as reforming water to be used for steam reforming. The water purifier 37 is a device for removing impurities contained in the recovered condensed water. For example, the water purifier 37 is filled with an ion exchange resin or the like, and converts electrolyte ions (e.g., ionized dissolved salts, ammonia, etc.) contained in the recovered condensed water into, for example, H + , O.H. - By replacing the electrolyte with the ion, the concentration of electrolyte contained in the recovered condensed water is relatively lowered (i.e., the electrical conductivity is lowered).

[0035] [Reformed water supply system] The reforming water supply system is a system that supplies reforming water to the reformer 15 via a reforming water supply passage L6. The fuel cell device 10 includes, as the reforming water supply system, a reforming water tank 38 that stores reforming water, a reforming water supply passage L6 through which the reforming water to be supplied to the vaporizer 14 flows, and a reforming water pump 39 that supplies the reforming water stored in the reforming water tank 38 to the vaporizer 14 via the reforming water supply passage L6. Specifically, the reforming water pump 39 is provided midway along the reforming water supply passage L6, and adjusts the flow rate per unit time of the reforming water flowing through the reforming water supply passage L6.

[0036] In the present application, the water recovery system and the reforming water supply system are collectively referred to as a water utilization system. That is, the water utilization system has a reforming water tank 38 as a recovered water tank for storing recovered water that can be recovered from the exhaust gas by cooling the exhaust gas in the exhaust heat recovery heat exchanger 34, and supplies the recovered water (reforming water) stored in the reforming water tank 38 for steam reforming of the raw fuel in the reformer 15.

[0037] An electrical conductivity meter 57 is provided in the reforming water supply passage L6 to measure the electrical conductivity of the reforming water supplied from the reforming water tank 38 to the vaporizer 14 via the reforming water supply passage L6. That is, the electrical conductivity meter 57 measures the electrical conductivity of the recovered water (reforming water) at a predetermined location in the water utilization system (water recovery system, reforming water supply system).

[0038] [Waste heat recovery system] The exhaust heat recovery system is a system that recovers heat generated by the fuel cell device 10. The exhaust heat recovery system includes a hot water storage tank 45 as a heat medium tank, a water supply line L8, a hot water outlet line L9, a hot water circulation line L7, and a circulation pump 44. The hot water storage tank 45 stores hot water as a heat medium. The hot water circulation line L7 circulates hot water between the hot water storage tank 45 and the exhaust heat recovery heat exchanger 34. The hot water storage tank 45 stores hot water such that relatively low temperature hot water is stored in the lower part and relatively high temperature hot water is stored in the upper part, i.e., in a state where temperature stratification is formed. The hot water circulation line L7 has an outward line L7a through which hot water flows from the hot water storage tank 45 to the exhaust heat recovery heat exchanger 34, and a return line L7b through which hot water flows from the exhaust heat recovery heat exchanger 34 to the hot water storage tank 45. A circulation pump 44 for circulating hot and cold water in the hot and cold water circulation path L7 is provided midway along the outgoing path L7a.

[0039] With this configuration, hot water supplied from the bottom of the hot water storage tank 45 to the exhaust heat recovery heat exchanger 34 via the outward line L7a of the hot water circulation path L7 is heated by the exhaust heat recovery heat exchanger 34, and the heated hot water is supplied to the top of the hot water storage tank 45 via the return line L7b of the hot water circulation path L7. A temperature measuring device T1 is provided along the return line L7b to measure the temperature of the hot water transferred from the exhaust heat recovery heat exchanger 34 to the hot water storage tank 45. In this embodiment, the fuel cell control unit 49 increases or decreases the output of the circulation pump 44, for example, the duty ratio of the PWM control of the circulation pump 44, so that the temperature of the hot water flowing through the return line L7b and into the hot water storage tank 45 (the temperature of the hot water measured by the temperature measuring device T1) reaches a predetermined hot water storage target temperature (e.g., 65°C). The fuel cell control unit 49 also obtains information on the rotational speed of the circulation pump 44 at that time. In this way, hot water is stored in the hot water storage tank 45 in a state where temperature stratification is formed, i.e., heat is stored.

[0040] When the circulation pump 44 is flowing hot and cold water normally, the correlation between the output of the circulation pump 44 and its rotational speed deviates by less than a reference value. For example, if a standard rotational speed (200 rpm) is determined for each output of the circulation pump 44 (e.g., 30%), then as long as the circulation pump 44 is flowing hot and cold water normally, the actual rotational speed will deviate from the standard rotational speed by less than the reference value (e.g., less than ±30%).

[0041] Additionally, the fuel cell device 10 includes a radiator 56 that cools the hot water flowing through the outgoing path L7a by circulating the air present in the outer container space 48 of the outer container 11. Specifically, the radiator 56 is provided midway along the outgoing path L7a of the hot water circulation path L7, and rotates a radiator fan 56a to circulate the air present inside the outer container 11, thereby cooling the hot water flowing through the outgoing path L7a.

[0042] The fuel cell device 10 also includes a temperature measuring device T2 as a first hot water temperature measuring device that measures the temperature of hot water flowing between the radiator 56 and the heat exchanger 34 for exhaust heat recovery, along the forward path L7a of the hot water circulation path L7, and a temperature measuring device T3 as a second hot water temperature measuring device that measures the temperature of hot water flowing between the hot water storage tank 45 and the radiator 56, along the forward path L7a of the hot water circulation path L7.

[0043] When the temperature of hot water measured by temperature measuring device T3 is equal to or higher than the set heat medium temperature, fuel cell control device 49 rotates radiator fan 56a of radiator 56. For example, when the temperature of hot water measured by temperature measuring device T3 is equal to or higher than the upper limit heat medium temperature, fuel cell control device 49 increases or decreases the output of radiator fan 56a of radiator 56, for example, the duty ratio of PWM control, so that the temperature of hot water measured by temperature measuring device T2 becomes equal to or lower than a target heat medium temperature that is lower than the above-mentioned upper limit heat medium temperature. In addition, fuel cell control device 49 can obtain information on the rotation speed of radiator fan 56a at that time.

[0044] When the radiator fan 56a is operating normally, the correlation between the output of the radiator fan 56a and its rotational speed has a deviation less than a reference value. For example, if a standard rotational speed (200 rpm) is determined for each output of the radiator fan 56a (e.g., 30%), when the radiator fan 56a is operating normally, the actual rotational speed will deviate from the standard rotational speed by less than the reference value (e.g., less than ±30%).

[0045] A water supply line L8 for supplying clean water to the hot water storage tank 45 is connected to the bottom of the hot water storage tank 45, and a hot water outlet line L9 for discharging the hot water stored in the hot water storage tank 45 is connected to the top of the hot water storage tank 45. The water supply pressure applied inside the water supply line L8 is applied to the hot water stored in the hot water storage tank 45. With this configuration, for example, when a water faucet (not shown) connected to the hot water outlet line L9 is opened, hot water is discharged from the hot water storage tank 45 into the hot water outlet line L9, and clean water is supplied to the hot water storage tank 45 from the water supply line L8.

[0046] The fuel cell device 10 includes a power conversion circuit unit 46 in an inner space 48 of the outer container 11, which converts the output power of the cell stack 18 into desired AC power and supplies the AC power to a single-phase three-wire power line 8 connected to the power grid. The power line 8 has a first voltage line, a second voltage line, and a neutral line.

[0047] The fuel cell device 10 includes a fuel cell control unit 49 as a control device that controls the operation of the fuel cell device 10, a memory unit 50 that stores information handled by the fuel cell device 10, and a communication unit 51. Measurement results from various measuring instruments included in the fuel cell device 10, the operating status of the devices, etc. are transmitted to the fuel cell control unit 49 via signal transmission lines (not shown) or the like, and the measurement results are stored in the memory unit 50. The fuel cell control unit 49 then transmits these measurement results and operating status from the communication unit 51 to the abnormality diagnosis device 4 at a predetermined timing. The fuel cell control unit 49 also transmits any abnormalities that appear in these measurement results and operating status from the communication unit 51 as part of the measurement results and operating status to the abnormality diagnosis device 4.

[0048] The fuel cell control unit 49 controls the operation of various devices such as the igniter 20, shutoff valve 26, raw fuel blower 30, reforming water pump 39, air blower 41, circulation pump 44, power conversion circuit unit 46, radiator 56, and ventilation fan 59.

[0049] Next, a method will be described in which the abnormality diagnosis device 4 diagnoses the details of an abnormality occurring in the fuel cell device 10 based on information received from the fuel cell device 10 installed in the facility 1 via the information communication line 2. The abnormality diagnosis device 4 includes a memory unit 4a and a diagnosis processing unit 4b.

[0050] The storage unit 4a of the abnormality diagnosis device 4 stores, for each of a plurality of abnormalities, the measurement results of at least one of the plurality of measuring devices possessed by the fuel cell device 10, an abnormality appearing in the operating state of the fuel cell device 10, and an abnormality diagnosis process for identifying one of a plurality of possible diagnosis results for the abnormality, including at least one of the cause of the abnormality and a method for dealing with the abnormality. Specifically, the abnormality diagnosis process is composed of a combination of a plurality of judgment processes for determining whether or not at least one of the measurement results of the measuring devices of the fuel cell device 10, the operating state of the devices, and the operating environment of the fuel cell device 10 meets predetermined judgment conditions. The judgment results of the judgment processes, which are determined depending on whether or not the judgment conditions are met, include at least one of a case where a transition to another judgment process is instructed and a case where a diagnosis result of the abnormality diagnosis process is identified.

[0051] The measurement results of the measuring instruments of the fuel cell device 10 described above include, for example, the measurement results of the temperature measuring instruments T1 to T3, the pressure measuring instrument 27, the raw fuel flow measuring instrument 28, the air flow measuring instrument 42, the electrical conductivity measuring instrument 57, and the like.

[0052] The operating status of the above-mentioned equipment includes, for example, whether the equipment is operating normally, whether an alarm has been issued, what the actual operating status of the equipment is (for example, what the values ​​of the output, target flow rate, target rotation speed, actual rotation speed, etc. of the raw fuel blower 30, reforming water pump 39, air blower 41, circulation pump 44, radiator 56, ventilation fan 59, etc. are, etc.), what process the fuel cell device 10 is currently performing, such as the start-up process, power generation process, or shutdown process, etc.

[0053] The operating environment of the fuel cell device 10 described above includes, for example, the state of the power system connected to the fuel cell device 10 (e.g., whether there is a power outage, etc.), whether the system is disconnected, the length of the system disconnection, the state of supply of raw fuel to the fuel cell device 10, the calorific value (gas type) of the raw fuel actually supplied, and the calorific value of the raw fuel expected to be used by the fuel cell device 10. Information on the state of the power system connected to the fuel cell device 10 (e.g., whether there is a power outage, etc.) may be provided by the information providing server device 3.

[0054] When an abnormality appears in the measurement results, operating state, or operating environment received from the fuel cell device 10 via the information communication line 2, the diagnostic processing unit 4b of the abnormality diagnostic device 4 identifies a diagnostic result for the abnormality based on the details of the abnormality diagnostic process corresponding to the abnormality stored in the memory unit 4a and at least one of the measurement results of the measuring instruments of the fuel cell device 10, the operating state of the equipment, and the operating environment of the fuel cell device 10. Here, whether or not the abnormality appears may be determined by the fuel cell device 10 or by the abnormality diagnostic device 4.

[0055] [Abnormality diagnosis processing] FIG. 3 is a flowchart showing the contents of the abnormality diagnosis process. In this embodiment, the fuel cell control unit 49 adjusts the output of the raw fuel blower 30 so that the raw fuel flow rate measured by the raw fuel flow rate measuring device 28 becomes equal to the target raw fuel flow rate. As described above, when the raw fuel blower 30 is supplying raw fuel normally, the output of the raw fuel blower 30 deviates from the standard output determined according to the target raw fuel flow rate by less than a reference value. For example, when the standard output of the raw fuel blower 30 is determined to supply raw fuel at a flow rate corresponding to the target raw fuel flow rate, the output of the raw fuel blower 30 will not exceed the standard output by more than a reference value as long as the raw fuel blower 30 is supplying raw fuel normally. On the other hand, for example, when pressure loss is large in the raw fuel supply system that supplies raw fuel to the reformer 15 via the raw fuel supply path L1, the output of the raw fuel blower 30 may become greater than the standard output determined according to the target raw fuel flow rate by a predetermined value or more (i.e., the target raw fuel flow rate cannot be achieved unless the output of the raw fuel blower 30 is increased).

[0056] In this way, abnormalities in the fuel cell system 10 can be diagnosed based on the relationship between the actual output of the raw fuel blower 30 and the standard output determined according to the target raw fuel flow rate. For example, it can be diagnosed that an abnormality has occurred in the exhaust heat recovery heat exchanger 34, which exchanges heat between hot water and exhaust gas, such that hot water is flowing into the exhaust gas flow path L4. Specifically, if an abnormality occurs in the exhaust heat recovery heat exchanger 34, causing hot water to flow into the exhaust gas flow path L4, impurities contained in the hot water will also flow into the exhaust gas flow path L4, and the water containing these impurities will be supplied to the vaporizer 14 and the reformer 15 for steam reforming. These impurities may then precipitate inside the vaporizer 14, the reformer 15, and other devices, potentially increasing pressure loss in the vaporizer 14, the reformer 15, and other devices. Furthermore, if an abnormality has occurred in the exhaust heat recovery heat exchanger 34, such as hot water flowing into the exhaust gas flow path L4, the electrical conductivity of the reforming water measured by the electrical conductivity meter 57 will also likely increase. Therefore, in this embodiment, the presence or absence of such an abnormality is diagnosed by executing the flowchart of the abnormality diagnosis process shown in FIG.

[0057] First, when a predetermined stop condition is satisfied, the fuel cell control unit 49 is configured to perform a stop process of stopping the supply of raw fuel to the reformer 15 and continuing a stopped state in which power generation in the fuel cell cells 17 is stopped for a first stop period. For example, if the raw fuel containing hydrocarbons, such as city gas, used in the fuel cell device 10 is supplied via a microcomputer meter with a gas leak detection function, the fuel cell control unit 49 stops power generation in the fuel cell device 10 as frequently as once every 27 days to avoid erroneously determining that the raw fuel has leaked. In this case, the fuel cell control unit 49 performs a stop process of stopping the supply of raw fuel to the reformer 15 and continuing a stopped state in which power generation in the fuel cell cells 17 is stopped for, for example, seven hours (an example of a first stop period).

[0058] If a raw fuel abnormality condition is met that the output of the raw fuel blower 30 is greater than the standard output corresponding to the target raw fuel flow rate by a predetermined value or more, the fuel cell control unit 49 executes the abnormality diagnosis process shown in the flowchart of FIG.

[0059] In step #10, the diagnostic processing unit 4b of the abnormality diagnostic device 4 makes the stop period in the stop processing performed on the fuel cell device 10 longer than the stop period performed in the previous stop processing. Then, the diagnostic processing unit 4b communicates the changed stop period to the fuel cell device 10. In other words, the diagnostic processing unit 4b causes the fuel cell device 10 to continue the stopped state for a second stop period, which is longer than the first stop period, in the stop processing performed thereafter.

[0060] When hot water is flowing into the exhaust gas flow path L4 in the exhaust heat recovery heat exchanger 34, a longer period of time that the stop state continues means that the total amount of hot water flowing into the exhaust gas flow path L4 in the exhaust heat recovery heat exchanger 34 during that time will increase. Also, in the stopped state, the reforming water pump 39 is not operating. Therefore, when hot water is flowing into the exhaust gas flow path L4 in the exhaust heat recovery heat exchanger 34, the longer the period of time that the stop state continues, the higher the concentration of impurities in the reforming water in the water utilization system (water recovery system, reforming water supply system).

[0061] Therefore, in step #11, if the electrical conductivity measured by the electrical conductivity meter 57 after the stopped state has continued for the second stop period satisfies a predetermined recovered water abnormality condition (i.e., if the answer is "Yes" in step #11), the diagnostic processing unit 4b determines that hot water is flowing into the exhaust gas flow path L4 in the exhaust heat recovery heat exchanger 34 (step #12). For example, if the electrical conductivity measured by the electrical conductivity meter 57 after the stopped state has continued for the second stop period is equal to or greater than a set value, the diagnostic processing unit 4b determines that the recovered water abnormality condition is satisfied.

[0062] Alternatively, the diagnostic processing unit 4b determines that the recovered water abnormality condition is met if the electrical conductivity measured by the electrical conductivity meter 57 after the stopped state has continued for the second stop period is equal to or greater than the set value, or if the electrical conductivity measured by the electrical conductivity meter 57 after the stopped state has continued for the second stop period is greater than the electrical conductivity measured by the electrical conductivity meter 57 after the stopped state has continued for the first stop period by a predetermined value or more.

[0063] On the other hand, if the electrical conductivity measured by the electrical conductivity meter 57 does not satisfy the recovered water abnormality condition, the process returns to the start of this flowchart. Then, in step #10, the length of the shutdown period in the shutdown process is further extended. If hot or cold water is flowing into the exhaust gas flow path L4 in the exhaust heat recovery heat exchanger 34, extending the length of the shutdown period further increases the concentration of impurities in the reforming water in the water utilization system (water recovery system, reforming water supply system), increasing the possibility that the recovered water abnormality condition will be satisfied.

[0064] 3. In addition, when the raw fuel abnormality condition, that is, the output of the raw fuel blower 30 is greater than the standard output corresponding to the target raw fuel flow rate by a predetermined value or more, is no longer satisfied, the diagnostic processing unit 4b does not need to execute the flowchart shown in Fig. 3. In addition, the diagnostic processing unit 4b may change the stop period in the stop process performed in the fuel cell device 10 to an initial value, and transmit the initial value of the stop period to the fuel cell device 10.

[0065] As described above, the abnormality diagnosis device 4 can automatically perform the process from the occurrence of an abnormality to the identification of a diagnosis result for that abnormality according to a pre-created abnormality diagnosis processing procedure. The identified diagnosis result is then stored in the memory unit 4a of the abnormality diagnosis device 4. The memory unit 4a of the abnormality diagnosis device 4 also stores at least one of the contact information for the manager (e.g., the owner) who manages the fuel cell device 10, the contact information for the maintenance staff of the fuel cell device 10, and the contact information for manufacturing personnel (e.g., the assembler or component manufacturer of the fuel cell device 10). The diagnosis processing unit 4b outputs the identified diagnosis result to at least one of the contact information for the manager, the contact information for the maintenance staff, and the contact information for manufacturing personnel. For example, the diagnosis processing unit 4b transmits the diagnosis result to the email addresses of the manager of the fuel cell device 10, the email addresses of the maintenance staff of the fuel cell device 10, and the email addresses of manufacturing personnel of the fuel cell device 10. As a result, the manager of the fuel cell device 10 can check the diagnosis result on his / her manager terminal device 62, the maintenance staff of the fuel cell device 10 can check the diagnosis result on their maintenance staff terminal device 60, and the manufacturing personnel of the fuel cell device 10 can check the diagnosis result on their manufacturing personnel terminal device 61. In this way, the abnormality diagnosis device 4 automatically identifies the diagnosis result for the abnormality, so that maintenance personnel can be dispatched after making preparations in advance according to the diagnosis result.

[0066] For example, before arriving at the site where repairs are to be performed on the fuel cell device 10, the person in charge of maintaining the fuel cell device 10 can prepare for repairs based on the diagnostic results, and the person involved in manufacturing the fuel cell device 10 can prepare the parts necessary for repairs based on the diagnostic results. As a result, it is possible to avoid problems such as a lack of skilled personnel at the site where repairs are to be performed, or problems such as not having the parts necessary for repairs brought with them.

[0067] In the above example, the diagnosis result of the abnormality diagnosis process includes the details of the malfunction occurring in a specific part of the fuel cell device 10 as the cause of the abnormality, such as "hot water is flowing into the exhaust gas flow path L4 in the exhaust heat recovery heat exchanger 34." If the details of the malfunction occurring in a specific part of the fuel cell device 10 as the cause of the abnormality are known, the manager, maintenance staff, manufacturing personnel, etc. of the fuel cell device 10 can determine the necessary work, such as repairing or replacing parts in that part.

[0068] The diagnostic results are not limited to the above-mentioned examples, but can be changed as appropriate. As a specific example, the diagnostic result may include an instruction to replace or repair a component of the fuel cell device 10 related to the diagnostic result as a measure to deal with the abnormality. For example, in the above embodiment, the diagnostic result may include an instruction to replace or repair the exhaust heat recovery heat exchanger 34.

[0069] If instructions for replacing or repairing components of the fuel cell device 10 as described above are included as a way to deal with abnormalities, the components to be replaced can be prepared in advance and the personnel required for the replacement or repair work can be determined in advance.

[0070] Additionally, when issuing an instruction to replace or repair a specific component of the fuel cell system 10, it is preferable to know the degree of difficulty. For this reason, the memory unit 4a stores information indicating the degree of difficulty of the repair or replacement work for each of the multiple components of the fuel cell system 10, and the diagnosis result may include information indicating the degree of difficulty as a way to deal with the abnormality. If information indicating the degree of difficulty of the component repair or replacement work is included as a way to deal with the abnormality, preparations can be made in advance to dispatch personnel with the skills appropriate to the degree of difficulty.

[0071] In addition, when issuing an instruction to replace or repair a specific component of the fuel cell system 10, it is preferable for the maintenance personnel who will actually perform the replacement or repair to be able to view video data explaining the repair or replacement work in advance or on-site. Therefore, the storage unit 4a stores video data explaining the repair or replacement work for each of multiple components of the fuel cell system 10, and the diagnosis results may include the video data as a way to deal with the abnormality. If video data explaining the repair or replacement work for the component of the fuel cell system 10 is included as a way to deal with the abnormality, the person performing the repair or replacement work for the component can review the video data and reliably perform the repair or replacement work.

[0072] <Another embodiment> In the above embodiment, the configuration of the abnormality diagnosis system has been specifically described, but the configuration can be changed as appropriate. Furthermore, the contents of the diagnosis results can be changed as appropriate.

[0073] In the above embodiment, the abnormality diagnosis system of the present invention has been described using numerical examples, but these numerical values ​​are given for illustrative purposes only and can be changed as appropriate.

[0074] The configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0075] The present invention can be used in an abnormality diagnosis system that can diagnose the cause of an operational abnormality in a raw fuel blower. [Explanation of symbols]

[0076] 1: Facility 2: Information and communication lines 4: Abnormality diagnosis device 10:Fuel cell device 15: Reformer 17: Fuel cell 18: Cell stack 19: Combustion section 28: Raw fuel flow rate measuring device 30: Raw fuel blower 34: Heat exchanger for exhaust heat recovery 38: Reformed water tank (recovered water tank) 41: Air blower 45: Hot water tank 49: Fuel cell control unit (control device) 57: Electrical conductivity measuring instrument L1: Raw fuel supply path L4: Exhaust gas flow path L10: Air supply line

Claims

1. An abnormality diagnosis system comprising: a fuel cell device installed in a facility; and an abnormality diagnosis device that diagnoses the details of an abnormality occurring in the fuel cell device based on information received from the fuel cell device via an information communication line, The fuel cell device includes a reformer that generates fuel gas by steam reforming a raw fuel, a cell stack having a plurality of fuel cell units each having an anode to which the fuel gas generated in the reformer is supplied and a cathode to which air is supplied, a raw fuel supply path through which the raw fuel supplied to the reformer flows, a raw fuel blower that supplies the raw fuel to the reformer via the raw fuel supply path, an air supply path through which air supplied to the cathode flows, an air blower that supplies air to the cathode via the air supply path, a combustion unit that combusts off-gas discharged from the cell stack, an exhaust gas flow path through which exhaust gas containing gas generated by combustion in the combustion unit flows, a hot water storage tank that stores hot water that has recovered heat from the exhaust gas, a heat exchanger for exhaust heat recovery provided midway through the exhaust gas flow path, and a hot water circulation unit configured to supply the hot water taken out of the hot water tank to the heat exchanger for exhaust heat recovery and return the hot water that has flowed through the heat exchanger for exhaust heat recovery to the hot water storage tank, thereby circulating the hot water so that the heat of the exhaust gas is recovered in the heat exchanger for exhaust heat recovery in the hot water storage tank; a water utilization system having a recovered water tank for storing recovered water that can be recovered from the exhaust gas by cooling the exhaust gas in the heat exchanger for exhaust heat recovery, and supplying the recovered water stored in the recovered water tank for steam reforming of the raw fuel in the reformer; a control device; a raw fuel flow rate measuring device for measuring the flow rate per unit time of the raw fuel supplied to the reformer via the raw fuel supply path; and an electrical conductivity measuring device for measuring the electrical conductivity of the recovered water at a predetermined location in the water utilization system; the control device of the fuel cell device is configured to adjust the output of the raw fuel blower so that the raw fuel flow rate measured by the raw fuel flow rate measuring device becomes a target raw fuel flow rate, and when a predetermined stop condition is satisfied, to perform a stop process of stopping the supply of the raw fuel to the reformer and continuing a stop state in which power generation in the fuel cell is stopped for a first stop period; The abnormality diagnosis device is an abnormality diagnosis system that, when a raw fuel abnormality condition is met in which the output of the raw fuel blower is greater than the standard output corresponding to the target raw fuel flow rate by a predetermined value or more, continues the stopped state for a second stop period longer than the first stop period in the subsequent shutdown process, and if the electrical conductivity measured by the electrical conductivity measuring device after the stopped state has continued for the second stop period meets a predetermined recovered water abnormality condition, determines that the hot water is flowing into the exhaust gas flow path in the exhaust heat recovery heat exchanger.

2. The abnormality diagnosis system described in claim 1, wherein the abnormality diagnosis device determines that the recovered water abnormality condition is satisfied if the electrical conductivity measured by the electrical conductivity measuring device is greater than or equal to a set value after the stopped state continues for the second stopped period.

3. The abnormality diagnosis system described in claim 1, wherein the abnormality diagnosis device determines that the recovered water abnormality condition is satisfied when the electrical conductivity measured by the electrical conductivity meter after the stopped state has continued for the second stop period is equal to or greater than a set value, or when the electrical conductivity measured by the electrical conductivity meter after the stopped state has continued for the second stop period is greater by a predetermined value or more than the electrical conductivity measured by the electrical conductivity meter after the stopped state has continued for the first stop period.

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