JP5834419B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system.

  As one type of fuel cell system, one shown in Patent Document 1 is known. As shown in FIG. 1 of Patent Document 1, the fuel cell system includes a first flow path (circulation path 6) for circulating the first fluid (8) toward the heat source (drive source 2), the first The first pump (10, circulation pump 10A) for pumping the fluid of the second, the second flow path (circulation path 12) for flowing the second fluid (14, hot water 14A), the second for pumping the second fluid By controlling one or both of the pump (20, circulation pump 20A), heat exchange means (heat exchanger 16, 16A) for exchanging heat between the first and second fluids, the first pump or the second pump A heat exchanging device including a control means (control unit 18) for adjusting a temperature difference before and after the heat source of the first fluid and adjusting a flow rate of the second fluid, and a processing method for realizing the heat exchanging process, Without exchanging endurance performance on the side, and without depending on the amount of heat on the heat source side. It is adapted to achieve the optimization.

  Moreover, what is shown by patent document 2 is known as another form of a fuel cell system. As shown in FIG. 1 of Patent Document 2, a fuel cell system includes a fuel reformer 11 that reforms fuel to obtain hydrogen, and a fuel cell body 12 that generates hydrogen by supplying hydrogen from the fuel reformer. An exhaust heat recovery device 14 that recovers exhaust heat generated from the fuel cell main body and the fuel reformer, and a control device 15 that controls the fuel reformer, the fuel cell main body, and the exhaust heat recovery device, and a temperature. The control device 15 includes a sensor 20 and switches between a continuous operation method and an intermittent operation method in which the start and stop are performed once or more in a day based on the output of the temperature sensor. The control device switches the operation based on the date, switches the operation based on the temperature of the city water, and switches the operation depending on the temperature and the state of the hot water tank.

JP 2003-139396 A JP 2004006217 A

  The fuel cell systems described in Patent Document 1 and Patent Document 2 described above have an exhaust heat recovery system that recovers exhaust heat, but when the exhaust heat recovery system becomes abnormal (for example, exhaust heat) The fuel cell system is not stopped when the recovered water becomes hot. On the other hand, it is required to provide a safety device that stops the fuel cell system when the exhaust heat recovery system becomes abnormal. In this case, it can be considered that the fuel cell system is stopped and operated by stopping the supply of the power supply voltage to the auxiliary machines constituting the fuel cell system. However, there has been a problem that it cannot be determined whether the supply of power supply voltage has been stopped due to an abnormality in the power supply for auxiliary equipment or whether the supply of power supply voltage has been stopped due to an abnormality in the exhaust heat recovery system.

  The present invention has been made to solve the above-described problems. In the fuel cell system, when a safety device for stopping the fuel cell system is provided when the exhaust heat recovery system becomes abnormal, an abnormality occurs. The purpose is to accurately determine the location.

In order to solve the above-described problems, the invention according to claim 1 is directed to a fuel cell that generates power with fuel and an oxidant gas, and heat exchange between the exhaust heat of the fuel cell and hot water storage to store the waste heat. Waste heat recovery system that recovers and stores in water, auxiliary power supply that supplies driving voltage to auxiliary equipment that supplies fuel, oxidant gas, and hot water, and driving voltage from the auxiliary power supply is supplied to the auxiliary equipment A power shut-off device provided in the power supply circuit that communicates and shuts off the power supply circuit according to the temperature of the hot water storage, a voltage detection device that detects the output voltage of the power supply for auxiliary equipment, and a temperature of the hot water storage A temperature sensor and a control device that controls the supply of fuel, oxidant gas, and hot water, and the power shut-off device senses the temperature of the hot water and deforms in accordance with the temperature. And a switch part that communicates and shuts off the power supply circuit according to deformation. Temperature sensor detects the temperature of hot water is sensed by the heat-sensitive part of the power shutoff device, the control device of the hot water detected by the output voltage and the temperature sensor of the power supply detected auxiliary device by the voltage detection device Judgment means for judging which of the auxiliary power supply and the exhaust heat recovery system is abnormal from the temperature is provided.

According to a second aspect of the present invention, in the first aspect , the judging means has the output voltage of the auxiliary power source detected by the voltage detecting device equal to or lower than a predetermined voltage and the hot water detected by the temperature sensor. When the temperature is lower than the predetermined temperature, it is determined that the auxiliary power supply is abnormal.

According to a third aspect of the present invention, in the first aspect of the present invention, the determining means is configured such that the output voltage of the auxiliary power source detected by the voltage detecting device is equal to or lower than a predetermined voltage, and the hot water detected by the temperature sensor. When the temperature is equal to or higher than a predetermined temperature, it is determined that the exhaust heat recovery system is abnormal.

According to a fourth aspect of the present invention, in the first aspect , the determining means has the output voltage of the auxiliary power source detected by the voltage detecting device equal to or lower than a predetermined voltage and the hot water detected by the temperature sensor. When the state where the temperature is equal to or higher than the predetermined temperature continues for the first predetermined time, it is determined that the exhaust heat recovery system is abnormal.

According to a fifth aspect of the present invention, in the first aspect, the determining means is configured such that the output voltage of the auxiliary power source detected by the voltage detection device is equal to or lower than a predetermined voltage and the hot water detected by the temperature sensor. When the state where the temperature is lower than the predetermined temperature continues for the second predetermined time, it is determined that the auxiliary power supply is abnormal.

  In the invention according to claim 1 configured as described above, in the fuel cell system, when the temperature of the hot water becomes equal to or higher than a predetermined operating temperature, the power shutoff device compensates for the drive voltage from the auxiliary power source. The power supply circuit supplying to the machine can be shut off. Therefore, a power shut-off device can be provided as a safety device for stopping the fuel cell system when the exhaust heat recovery system becomes abnormal (for example, when the stored hot water becomes hot). Further, the determining means determines which of the auxiliary power source and the exhaust heat recovery system is abnormal based on the output voltage of the auxiliary power source detected by the voltage detector and the temperature of the hot water detected by the temperature sensor. judge. As a result, when the fuel cell system is configured to stop the supply of the power supply voltage to the auxiliary machine, the supply of the power supply voltage is stopped due to an abnormality in the auxiliary power supply. It is possible to accurately determine whether the supply of the power supply voltage has been stopped due to an abnormality in the heat recovery system, that is, where the abnormality has occurred.

Also, power shut-off device is provided with a heat-sensitive portion that deforms in response to the sensed temperature change the temperature of the hot water, a switch portion communicating and blocking the power supply circuit according to the deformation of the heat-sensitive part, the The temperature sensor is installed in the vicinity of the power shut-off device and detects the temperature of the hot water stored in the heat-sensing part of the power shut-off device. Can be determined more accurately.

In the invention according to claim 2 configured as described above, in claim 1 , the determination means is configured such that the output voltage of the auxiliary power source detected by the voltage detection device is equal to or lower than a predetermined voltage, and the temperature sensor When the detected temperature of the stored hot water is lower than a predetermined temperature, it is determined that the auxiliary power supply is abnormal. This makes it possible to accurately determine that the auxiliary power supply is abnormal.

In the invention according to claim 3 configured as described above, in claim 1 , the determination means is configured such that the output voltage of the auxiliary power source detected by the voltage detection device is equal to or lower than a predetermined voltage, and the temperature sensor When the detected hot water temperature is equal to or higher than a predetermined temperature, it is determined that the exhaust heat recovery system is abnormal. Thereby, it can be determined accurately that the exhaust heat recovery system is abnormal.

In the invention according to claim 4 configured as described above, in claim 1 , the determination means is configured such that the output voltage of the auxiliary power source detected by the voltage detection device is equal to or lower than a predetermined voltage, and the temperature sensor When the detected hot water temperature is equal to or higher than the predetermined temperature continues for the first predetermined time, it is determined that the exhaust heat recovery system is abnormal. This makes it possible to accurately and accurately determine that the exhaust heat recovery system is abnormal.

In the invention according to claim 5 configured as described above, in claim 1, the determination means is configured such that the output voltage of the auxiliary power source detected by the voltage detection device is equal to or lower than a predetermined voltage, and the temperature sensor When the state where the detected hot water temperature is lower than the predetermined temperature continues for the second predetermined time, it is determined that the auxiliary power supply is abnormal. This makes it possible to accurately and accurately determine that the auxiliary power supply is abnormal.

It is a schematic diagram showing an outline of one embodiment of a fuel cell system according to the present invention. It is sectional drawing which shows the structure of the power supply interruption | blocking apparatus shown in FIG. 1, (a) has shown the state which closed the power supply circuit, (b) has shown the state which has opened the power supply circuit. It is a block diagram which shows the fuel cell system shown in FIG. It is a flowchart of the control program (abnormality determination) performed with the control apparatus shown in FIG. It is a time chart of one Example when the flowchart shown in FIG. 4 is performed. It is a flowchart of the control program (abnormality determination) performed with the control apparatus shown in FIG. It is a time chart of one Example when the flowchart shown in FIG. 6 is performed. It is a flowchart of the control program (process after power supply failure determination for auxiliary machines) executed by the control device shown in FIG. It is a flowchart of the control program (process after exhaust heat recovery system abnormality determination) performed with the control apparatus shown in FIG.

  Hereinafter, an embodiment of a fuel cell system according to the present invention will be described. FIG. 1 is a schematic diagram showing an outline of this fuel cell system. The fuel cell system includes a box-shaped casing 11, a fuel cell module 20, an exhaust heat recovery system 30, an inverter device 50, and a control device 60.

  The case 11 includes a partition member 12 that partitions the inside of the case 11 and forms a first chamber R1 and a second chamber R2. The first chamber R1 forms a first space, and the second chamber R2 forms a second space. The partition member 12 is a plate-like member that partitions (divides) the casing 11 in the vertical direction. A first chamber R1 and a second chamber R2 are formed in the housing 11 above and below the partition member 12.

  The fuel cell module 20 is accommodated in the first chamber R1 with a space from the inner wall surface of the first chamber R1. The fuel cell module 20 includes at least a casing 21 and a fuel cell 24. In the present embodiment, the fuel cell module 20 includes a casing 21, an evaporation unit 22, a reforming unit 23, and a fuel cell 24.

  The casing 21 is formed in a box shape with a heat insulating material. The casing 21 is supported in the first chamber R1 by a support structure (not shown) with a space from the inner wall surface of the first chamber R1. In the casing 21, an evaporation unit 22, a reforming unit 23, and a fuel cell 24 are disposed. At this time, the evaporation unit 22 and the reforming unit 23 are disposed above the fuel cell 24.

  The evaporation unit 22 is heated by a combustion gas, which will be described later, to evaporate the supplied reforming water to generate water vapor, and to preheat the supplied reforming raw material. The evaporation unit 22 mixes the steam generated in this way with the preheated reforming raw material and supplies it to the reforming unit 23. Examples of the reforming raw material include natural gas, gas fuel for reforming such as LPG, and liquid fuel for reforming such as kerosene, gasoline, and methanol. In the present embodiment, description will be made on natural gas.

  One end (lower end) of the water supply pipe 41 provided in the water tank 13 is connected to the evaporation unit 22. The water supply pipe 41 is provided with a reforming water pump 41a. The reforming water pump 41a supplies reforming water to the evaporation unit 22 and adjusts the reforming water supply amount.

  The evaporating unit 22 is supplied with a reforming material from a fuel supply source (not shown) through a reforming material supply pipe 42. The reforming raw material supply pipe 42 is provided with a pair of raw material valves (not shown), a desulfurizer 42a, and a raw material pump 42b in order from the upstream. The raw material valve is an electromagnetic on-off valve that opens and closes the reforming raw material supply pipe 42. The desulfurizer 42a removes a sulfur content (for example, a sulfur compound) in the reforming raw material. The raw material pump 42b adjusts the amount of fuel supplied from the fuel supply source.

  The reforming unit 23 is heated by a combustion gas, which will be described later, and supplied with heat necessary for the steam reforming reaction, so that the reformed gas is generated from the mixed gas (reforming raw material, steam) supplied from the evaporation unit 22. Is generated and derived. The reforming unit 23 is filled with a catalyst (for example, Ru or Ni-based catalyst), and the mixed gas reacts with the catalyst to be reformed to generate hydrogen gas and carbon monoxide gas (so-called so-called). Steam reforming reaction). At the same time, a so-called carbon monoxide shift reaction occurs in which carbon monoxide generated in the steam reforming reaction reacts with steam to transform into hydrogen gas and carbon dioxide. These generated gases (so-called reformed gas) are led out to the fuel electrode of the fuel cell 24. The reformed gas contains hydrogen, carbon monoxide, carbon dioxide, water vapor, and unreformed natural gas (methane gas). The steam reforming reaction is an endothermic reaction, and the carbon monoxide shift reaction is an exothermic reaction.

  The fuel cell 24 is configured by laminating a fuel electrode, an air electrode (oxidant electrode), and a plurality of cells 24a made of an electrolyte interposed between the two electrodes. The fuel cell of the present embodiment is a solid oxide fuel cell, and uses zirconium oxide, which is a kind of solid oxide, as an electrolyte. Hydrogen, carbon monoxide, methane gas, etc. are supplied to the fuel electrode of the fuel cell 24 as fuel. The operating temperature is about 400-1000 ° C. Not only hydrogen but also natural gas and coal gas can be used directly as fuel. In this case, the reforming unit 23 can be omitted.

  On the fuel electrode side of the cell 24a, a fuel flow path 24b through which a reformed gas that is a fuel flows is formed. An air flow path 24c through which air (cathode air) that is an oxidant gas flows is formed on the air electrode side of the cell 24a.

  The fuel cell 24 is provided on the manifold 25. The reformed gas from the reforming unit 23 is supplied to the manifold 25 through the reformed gas supply pipe 43. The lower end (one end) of the fuel flow path 24b is connected to the fuel outlet port of the manifold 25, and the reformed gas led out from the fuel outlet port is introduced from the lower end and led out from the upper end. . Cathode air sent out by the cathode air blower 44a (cathode air sending (blowing) means) is supplied via the cathode air supply pipe 44, introduced from the lower end of the air flow path 24c, and led out from the upper end. .

  The cathode air blower 44a is disposed in the second chamber R2. The cathode air blower 44a sucks the air in the second chamber R2 and discharges it to the air electrode of the fuel cell 24. The discharge amount is adjusted and controlled (for example, the load power amount (power consumption amount) of the fuel cell 24). Are controlled accordingly).

In the fuel cell 24, power generation is performed by the fuel supplied to the fuel electrode and the oxidant gas supplied to the air electrode. That is, the reaction shown in Chemical Formula 1 and Chemical Formula 2 below occurs at the fuel electrode, and the reaction shown in Chemical Formula 3 below occurs at the air electrode. That is, oxide ions (O ²⁻ ) generated at the air electrode permeate the electrolyte and react with hydrogen at the fuel electrode to generate electrical energy. Therefore, the reformed gas and the oxidant gas (air) that have not been used for power generation are derived from the fuel flow path 24b and the air flow path 24c.

(Chemical formula 1)
H ₂ + O ²⁻ → H ₂ O + 2e ⁻

(Chemical formula 2)
CO + O ²⁻ → CO ₂ + 2e ⁻

(Chemical formula 3)
1 / 2O ₂ + 2e ⁻ → O ²⁻

  The reformed gas derived from the fuel flow path 24b and the air flow path 24c and not used for power generation is generated in the combustion space R3 between the fuel cell 24 and the evaporation section 22 (reforming section 23). The oxidant gas (air) that has not been used is combusted, and the evaporation part 22 and the reforming part 23 are heated by the combustion gas. Furthermore, the inside of the fuel cell module 20 is heated to the operating temperature. Thereafter, the combustion gas is exhausted out of the fuel cell module 20 through the exhaust port 21a.

  The exhaust heat recovery system 30 is an exhaust heat recovery system that recovers and stores exhaust heat in stored hot water by exchanging heat between the exhaust heat of the fuel cell 24 and the stored hot water. The exhaust heat recovery system 30 includes a hot water tank 31 for storing hot water, a hot water circulation line 32 for circulating the hot water, and heat exchange in which heat is exchanged between the combustion exhaust gas from the fuel cell module 20 and the hot water. A device 33 is provided.

  The hot water storage tank 31 is provided with one columnar container, in which hot water is stored in a layered manner, that is, the temperature of the upper part is the highest and lower as it goes to the lower part, and the temperature of the lower part is the lowest. It has become so. Water (low-temperature water) such as tap water is replenished to the lower part of the columnar container of the hot water tank 31, and hot hot water stored in the hot water tank 31 is led out from the upper part of the columnar container of the hot water tank 31. ing.

  One end of the hot water circulation line 32 is connected to the lower part of the hot water tank 31, and the other end is connected to the upper part of the hot water tank 31. On the hot water circulating line 32, there are a hot water circulating pump 32a, a first temperature sensor 32b, a heat exchanger 33, a second temperature sensor 32c, and a third temperature sensor 32d, which are hot water circulating means in order from one end to the other end. It is arranged. The hot water circulating pump 32a sucks in hot water stored in the lower part of the hot water tank 31, passes the hot water circulating line 32 in the direction of the arrow in the drawing, and discharges it to the upper part of the hot water tank 31, and its flow rate (delivery amount) is controlled. It has come to be. The hot water circulating pump 32a is controlled in its delivery amount so that the temperature detected by the third temperature sensor 32d (the inlet temperature of the hot water storage tank 31) is within a predetermined temperature or temperature range.

  The first temperature sensor 32 b is a hot water circulation line 32 on the hot water introduction side of the heat exchanger 33, and is disposed between the heat exchanger 33 and the hot water tank 31. The first temperature sensor 32 b detects the inlet temperature of the hot water storage heat exchanger 33, that is, the outlet temperature of the hot water storage hot water tank 31, and transmits the detection result to the control device 60.

  The second temperature sensor 32 c is a hot water circulation line 32 on the hot water discharge side of the heat exchanger 33, and is disposed between the heat exchanger 33 and the hot water tank 31. In other words, the second temperature sensor 32 c is disposed in the vicinity of the power shutoff device 56 and detects the temperature of the hot water stored in the power shutoff device 56 (temperature sensing). The second temperature sensor 32 c detects the outlet temperature of the hot water storage heat exchanger 33, that is, the temperature in the vicinity of the hot water power shutoff device 56, and transmits the detection result to the control device 60. Yes.

  The third temperature sensor 32 d is disposed between the hot water circulation line 32 on the hot water discharge side of the heat exchanger 33 and the power shut-off device 56 and the hot water storage tank 31. The third temperature sensor 32 d detects an outlet temperature of the hot water storage heat exchanger 33, that is, an inlet temperature of the hot water storage tank 31, and transmits the detection result to the control device 60. The second temperature sensor 32c and the third temperature sensor 32d may be integrated into one instead of being separated.

  The heat exchanger 33 is a heat exchanger that is supplied with the combustion exhaust gas exhausted from the fuel cell module 20 and is supplied with hot water from the hot water storage tank 31 to exchange heat between the combustion exhaust gas and the hot water. The heat exchanger 33 is disposed in the housing 11. In the present embodiment, the heat exchanger 33 is provided in the lower part of the fuel cell module 20, and at least the lower part of the heat exchanger 33 penetrates the partition member 12 and is protruded into the second chamber R <b> 2. ing.

  The heat exchanger 33 includes a casing 33a. Connected to the upper part of the casing 33a is a connecting pipe 45 that is provided at the lower part of the casing 21 of the fuel cell module 20 and communicates with an exhaust port 21a through which combustion exhaust gas is led out. An exhaust pipe 46 connected to the first exhaust port 11a is connected to the lower part of the casing 33a. A condensed water supply pipe 47 connected to the deionizer 14 is connected to the bottom of the casing 33a. A heat exchanging part (condensing part) 33 b connected to the hot water circulation line 32 is disposed in the casing 33 a.

  In the heat exchanger 33 configured as described above, the combustion exhaust gas from the fuel cell module 20 is introduced into the casing 33a through the connection pipe 45, and passes through the heat exchange section 33b through which the hot water is circulated. Heat is exchanged with water to be condensed and cooled. The condensed combustion exhaust gas passes through the exhaust pipe 46 and is discharged from the first exhaust port 11a to the outside. Further, the condensed water condensed is supplied to the pure water device 14 through the condensed water supply pipe 47 (water falls by its own weight). On the other hand, the hot water stored in the heat exchanger 33b is heated and discharged.

  Further, on the hot water storage line 32, a power shutoff device 56 is provided between the heat exchanger 33 and the hot water tank 31 in the hot water circulation line 32 on the hot water discharge side of the heat exchanger 33. The power shutoff device 56 is provided in the power supply circuit 57 that supplies the drive voltage from the auxiliary machine power supply 55 (inverter device 50) to the auxiliary machine, and communicates and cuts off the power supply circuit 57 according to the temperature of the hot water storage water. Is. In this embodiment, the power shut-off device 56 is provided between the auxiliary power source 55 and the auxiliary drive circuit 60a, but between the auxiliary drive circuit 60a and the auxiliary device, between the inverter device 50 and the auxiliary device. You may make it provide between the power supplies 55 for machines.

  As shown in FIG. 2, the power shut-off device 56 includes a housing 56a, a heat sensitive part 56b, a cap 56c, a switch part 56d, and a drive pin 56e. The housing 56a includes a bottomed cylindrical main body case 56a1 and a support 56a2.

  The heat sensitive part 56b senses the temperature of the hot water and deforms according to the temperature change. The heat sensitive part 56b is held on the outer surface of the support 56a2, and is made of, for example, a bimetal or a shape memory alloy. When the temperature of the heat sensitive part 56b becomes higher than a predetermined operating temperature (for example, 97 ° C.) due to the temperature rise of the hot water, the heat sensitive part 56b is deformed due to the difference in thermal expansion coefficient of the metal constituting the heat sensitive part 56b (downward). The drive pin 56e is driven to deform the movable spring piece 56d2. In addition, once the heat-sensitive part 56b is deformed once the operating temperature is exceeded, in order to return to the original shape, the target temperature must be a predetermined return temperature (for example, 70 ° C.) lower than the operating temperature. That is, if the temperature of the heat sensitive part 56b becomes less than the return temperature, the heat sensitive part 56b returns with the upper side protruding as shown in FIG.

  The cap 56c is fitted to the outside of the main body case 56a1 from above the support 56a2, and fixes the heat sensitive part 56b to the support 56a2. At this time, the peripheral part of the heat sensitive part 56b is sandwiched between the cap 56c and the support 56a2, and the central part of the heat sensitive part 56b can be deformed according to the temperature of the hot water stored. An opening 56c1 is formed in a portion of the cap 56c that faces the heat sensitive portion 56b. Thereby, the heat sensitive part 56b can receive the heat of the vicinity where this power supply interruption | blocking apparatus 56 is installed.

  The switch portion 56d is a switch that communicates and shuts off the power supply circuit 57 according to the deformation of the heat sensitive portion 56b, and is provided inside the housing 56a. The switch portion 56d has a fixed contact 56d1 fixed to a substantially central portion of the cylindrical portion of the main body case 56a1 and connected to the terminal 56f, and a base end fixed to the cylindrical portion of the main body case 56a1 and connected to the terminal 56g. The movable spring piece 56d2 and the movable contact 56d3 provided at the tip of the movable spring piece 56d2 and facing the fixed contact 56d1 are configured. The switch unit 56d is connected to the power supply circuit 57 via terminals 56f and 56g.

  The movable spring piece 56d2 is urged so that the movable contact 56d3 contacts the fixed contact 56d1, and when a drive pin 56e described later is not pressed downward, the movable contact 56d3 contacts the fixed contact 56d1. Therefore, the switch part 56d is in a closed state (see FIG. 2A). At this time, the power supply circuit 57 is in communication. On the other hand, when the drive pin 56e is pressed downward, the movable spring piece 56d2 is pressed downward against its urging force, so that the movable contact 56d3 is separated from the fixed contact 56d1, so that the switch portion 56d is opened. Yes (see FIG. 2 (b)). At this time, the power supply circuit 57 is shut off.

  The drive pin 56e is pivotally supported at the central portion of the support 56a2 so as to be slidable in the central axis direction of the main body case 56a1. The drive pin 56e is disposed between the heat sensitive part 56b and the movable spring piece 56d2 of the switch 56d, and is movably held by the heat sensitive part 56b and the movable spring piece 56d2 of the switch 56d. The drive pin 56e is driven by the deformation of the heat sensitive part 56b and transmits the deformation to the switch part 56d.

  Further, the fuel cell system includes a water tank 13 and a deionizer 14 as shown in FIG. The water tank 13 and the deionizer 14 are disposed in the second chamber R2. The water tank 13 stores pure water derived from the pure water device 14. The pure water tank 13 is provided with a water amount sensor (water level sensor) (not shown) that detects the amount of pure water in the pure water tank 13. The water amount sensor is, for example, a float type or capacitance type water level gauge. The water amount sensor transmits a detection signal to the control device.

  The pure water device 14 contains activated carbon and an ion exchange resin, and is filled with, for example, flaky activated carbon and a granular ion exchange resin. Depending on the state of the water to be treated, a hollow fiber filter may be installed. The deionizer 14 purifies the condensed water from the heat exchanger 33 with activated carbon and ion exchange resin. The deionizer 14 communicates with the deionized water tank 13 through a pipe 48, and the deionized water in the deionizer 14 is led to the deionized water tank 13 through the pipe 48.

  Further, the fuel cell system includes an air inlet port 11c formed in the casing 11 forming the second chamber R2, an air outlet port 11b formed in the casing 11 forming the first chamber R1, and a partition member 12. And a ventilation air blower 15 provided in the air inlet 12a formed in the above. When the ventilation air blower 15 is activated, outside air is sucked into the second chamber R2 through the air inlet port 11c, and is sent into the first chamber R1 by the ventilation air blower 15, and the air in the first chamber R1. Is discharged to the outside through the air outlet 11b.

  Further, the fuel cell system includes an inverter device 50. The inverter device 50 has a first function of inputting a DC voltage output from the fuel cell 24, converting the DC voltage to a predetermined AC voltage, and outputting the AC voltage to a power line 52 connected to an AC system power supply 51 and an external power load 53. The second function is to input an AC voltage from the system power supply 51 through the power supply line 52, convert the AC voltage to a predetermined DC voltage, and output it to the control power supply 54 and the auxiliary power supply 55.

  The system power supply (or commercial power supply) 51 supplies power to the power load 53 via a power supply line 52 connected to the system power supply 51. The fuel cell 24 is connected to the power supply line 52 via the inverter system 15. The power load 53 is a load driven by an AC power supply, and is an electrical appliance such as a dryer, a refrigerator, or a television.

  The control power supply 54 converts (eg, steps down) the DC voltage output from the inverter device 50 into a predetermined DC voltage (eg, 5V) and supplies the converted voltage to the control device 60 as a power supply voltage.

  The auxiliary power source 55 converts the direct current voltage output from the inverter device 50 into a predetermined direct current voltage (for example, 24 V) (for example, step-down), and is used for the auxiliary device provided in the power shut-off device 56 and the control device 60. The power supply voltage is supplied to the auxiliary machine via the drive circuit 60a. The auxiliary power source 55 is controlled by an instruction from the control device 60. The voltage sensor 55a, which is a voltage detection device, detects the output voltage from the auxiliary power source 55 and transmits it to the control device 60.

  The auxiliary equipment includes motor-driven pumps 41a and 42b for supplying reforming raw materials, water, and air to the fuel cell module 20, a ventilation air blower 15, a cathode air blower 44a, and the like. This auxiliary machine is driven by a DC voltage.

  Further, the fuel cell system includes a control device 60. The control device 60 is connected to the temperature sensors 32b, 32c, 32d, the voltage sensor 55a, the pumps 32a, 41a, 42b, the blowers 15, 44a, and the auxiliary power source 55 (see FIG. 3). The control device 60 includes a microcomputer (not shown), and the microcomputer includes an input / output interface, a CPU, a RAM, and a ROM (all not shown) connected via a bus. The CPU is operating the fuel cell system. The RAM temporarily stores variables necessary for executing the program, and the ROM stores the program.

  Next, the operation of the above-described fuel cell system will be described. The control device 60 monitors the output voltage V of the auxiliary power source 55. If the output voltage V is not output due to a failure of the auxiliary power source 55 or the like, the fuel cell system Stop operation to stop the power generation operation (or start-up operation). The stop operation is an operation for stopping supply of the reforming raw material, reforming water, and cathode air supplied to the fuel cell system. Specifically, driving of the raw material pump 42b, the reforming water pump 41a, and the cathode air blower 44a which are auxiliary machines is stopped. In addition, in order to seal the fuel cell system, closing an electromagnetic valve as an auxiliary machine is also included.

  In the fuel cell system, in order to cope with the temperature abnormality of the exhaust heat recovery system, countermeasures (software countermeasures) and mechanical countermeasures are taken. A soft countermeasure is to monitor the temperature of hot water (for example, the temperature of hot water supplied from the heat exchanger 33 to the hot water tank 31), and when the temperature reaches a predetermined temperature (for example, 90 ° C.) or higher, the system Is to stop operation. A mechanical countermeasure is to provide the power shut-off device 56 described above. As a result, even if the temperature of the exhaust heat recovery system becomes abnormal, the system can be stopped.

  A first control example of abnormality determination among the operations of the fuel cell system described above will be described with reference to FIGS. 4 and 5. When a start switch (not shown) is turned on, the control device 60 starts executing a program corresponding to the flowchart shown in FIG. The control device 60 operates the auxiliary power source 55 (step 102), and reads the output voltage V of the auxiliary power source 55 from the voltage sensor 55a (step 104).

  In step 106, the control device 60 determines whether or not the read output voltage V is lower than the determination voltage VL for a predetermined time TM0. If the state in which the output voltage V is equal to or lower than the determination voltage VL is not continued for the predetermined time TM0, the control device 60 determines “NO” in step 106 and repeats the processing in steps 104 and 106. On the other hand, when the state where the output voltage V is equal to or lower than the determination voltage VL continues for the predetermined time TM0, the control device 60 determines “YES” in step 106 and advances the program to step 108. The determination voltage VL is preferably set to a value equal to or lower than the lower limit value of the output rating of the auxiliary power source 55. In this embodiment, since the output rating is 24V ± 10%, for example, the determination voltage VL is set to 21V.

  In step 108, the control device 60 reads the temperature Th1 of the hot water power shutoff device 56 from the temperature sensor 32c. In step 110, the control device 60 determines whether or not the read temperature Th1 is equal to or higher than the determination temperature ThU. If the temperature Th1 of the hot water supply power shutoff device 56 is equal to or higher than the determination temperature ThU, the control device 60 determines “YES” in step 110 and determines that the temperature of the exhaust heat recovery system is abnormal ( Step 112).

  On the other hand, when the temperature Th1 of the hot water supply power shutoff device 56 is lower than the determination temperature ThU, the control device 60 determines “NO” in step 110 and determines that the auxiliary power supply 55 is in failure. (Step 114).

  The determination temperature ThU is preferably set to be higher than the temperature of the hot water to be supplied to the hot water tank 31 because it is set to 75 to 85 ° C. It is preferable to set it to a low temperature. The temperature abnormality of the exhaust heat recovery system is that the temperature of the stored hot water is higher than the judgment temperature, and the hot water storage water circulation line is caused by the pump 32a being air-engaged, the supply error of hot water at the time of construction, water leakage, etc. Occurs when the required amount of hot water is not allowed to flow through 32.

  Also, the failure of the auxiliary machine power supply 55 is caused by, for example, a failure of the auxiliary machine power supply 55 itself, a current abnormality due to a failure of the auxiliary machine at the power supply destination, etc. When stopping the operation, overvoltage is applied to the power line (circuit component failure, lightning, noise, etc.).

  For example, as shown in FIG. 5, when the output voltage V of the auxiliary power supply 55 starts to decrease at time t1, and then the output voltage V becomes 0V, the output voltage V becomes equal to or lower than the determination voltage VL at time t2. The state continues from time t2 to time t3, that is, for a predetermined time TM0. At this time, as shown by the solid line in FIG. 5B, when the temperature of the hot water storage system rises due to an abnormality in the exhaust heat recovery system, the temperature Th1 of the hot water power shutoff device 56 at time t3. Is equal to or higher than the determination temperature ThU, the control device 60 determines that the temperature of the exhaust heat recovery system is abnormal (step 112). On the other hand, when there is no temperature abnormality in the exhaust heat recovery system, as indicated by the broken line in FIG. 5B, the temperature Th1 of the hot water power shutoff device 56 is less than the determination temperature ThU at time t3. The control device 60 determines that the auxiliary power supply 55 is out of order (step 114).

  Further, a second control example of abnormality determination among the operations of the fuel cell system described above will be described with reference to FIGS. When a start switch (not shown) is turned on, the control device 60 starts executing a program corresponding to the flowchart shown in FIG. The control device 60 operates the auxiliary power source 55 (step 202), and reads the output voltage V of the auxiliary power source 55 from the voltage sensor 55a (step 204).

  The control device 60 reads the temperature Th1 of the hot water supply power shutoff device 56 from the temperature sensor 32c (step 206). In step 208, the control device 60 determines whether or not the state where the read output voltage V is equal to or lower than the determination voltage VL and the read temperature Th1 is equal to or higher than the determination temperature ThU continues for a predetermined time TM1. Determine. When the above-described state continues for the predetermined time TM1, when the predetermined time TM1 elapses, the control device 60 determines “YES” in step 208, and the temperature of the exhaust heat recovery system is abnormal. (Step 210).

  On the other hand, when the above-described state does not continue for the predetermined time TM1, the control device 60 reads the output voltage V of the auxiliary power source 55 from the voltage sensor 55a (step 212). Then, the control device 60 determines whether or not the read output voltage V is equal to or lower than the determination voltage VL for a predetermined time TM2 longer than the predetermined time TM1. The control device 60 repeats the processes of steps 204 to 214 when the above-described state is not continued for the predetermined time TM2. On the other hand, when the above-described state continues for the predetermined time TM2, when the predetermined time TM2 elapses, the control device 60 determines “YES” in step 214, and the auxiliary power supply 55 fails. (Step 216).

  For example, as shown in FIG. 7, when the output voltage V of the auxiliary power supply 55 starts to decrease at time t11 and then the output voltage V becomes 0V, the output voltage V becomes equal to or lower than the determination voltage VL at time t12. The state continues at least from time t12 to time t14, that is, for a predetermined time TM2.

  At this time, as shown by the solid line in FIG. 7B, when the exhaust heat recovery system is abnormal and the temperature of the stored hot water is rising, at time t13 (when a predetermined time TM1 has elapsed from time t12). The state where the output voltage V is equal to or lower than the determination voltage VL and the read temperature Th1 is equal to or higher than the determination temperature ThU continues for a predetermined time TM1. Therefore, the control device 60 determines “YES” in step 208 and determines that the temperature of the exhaust heat recovery system is abnormal (step 210).

  On the other hand, when there is no temperature abnormality in the exhaust heat recovery system, as shown by the broken line in FIG. 7B, at time t13, the output voltage V is equal to or lower than the determination voltage VL, but the temperature Th1 is lower than the determination temperature ThU. Therefore, the control device 60 determines “NO” in steps 208 and 214, respectively. Thereafter, at time t14 (when the predetermined time TM2 has elapsed from time t12), the state where the output voltage V is equal to or lower than the determination voltage VL continues for the predetermined time TM2. Therefore, the control device 60 determines “YES” in step 214, and determines that the auxiliary power supply 55 is out of order (step 216).

  Next, the control after the above-described fuel cell system abnormality determination is performed (whether or not the system can be restarted) will be described. First, a case where it is determined that the auxiliary power supply 55 is in failure will be described with reference to FIG. When a start switch (not shown) is turned on, the control device 60 starts executing a program corresponding to the flowchart shown in FIG. The control device 60 repeatedly executes the determination in step 302 until it determines that the auxiliary power supply 55 is out of order. When it is determined that the auxiliary power supply 55 is out of order, the control device 60 determines “YES” in step 302, advances the program to step 304, and stops the system started in another flowchart. It is determined whether or not the operation process has been completed.

  The control device 60 repeatedly executes the determination in step 304 until the system stop operation process is completed. When it is determined that the system stop operation process has been completed, the control device 60 determines “YES” in step 304 and advances the program to step 306.

  In step 306, the control device 60 reads the output voltage V of the auxiliary power source 55 from the voltage sensor 55a, and determines whether or not the output voltage V is equal to or lower than the determination voltage VL. For example, when the output voltage V is lower than the determination voltage VL due to a problem such as a temporary temperature rise around the circuit of the auxiliary power supply 55, the disturbance is removed and the voltage is restored to determine the output voltage V. When the voltage becomes higher than the voltage VL, the control device 60 determines “NO” in step 306, permits the system to be restarted, and starts the start-up operation (power generation operation) (step 308).

  On the other hand, when the output voltage does not recover, specifically, when the state where the output voltage V is equal to or lower than the determination voltage VL continues for the predetermined time TM3, the control device 60 performs steps 306 and 310. Each is determined as “YES”, and the standby state is maintained without permitting restart of the system (step 310). The predetermined time TM3 is set to a time sufficiently longer than the predetermined times TM1 and TM2 described above, and is set to a time sufficient for cooling the inside of the system. The predetermined time TM3 may be an elapsed time from the time when it is determined that an abnormality has occurred, or may be an elapsed time from the time when the system stop operation process is completed. The standby state is a state in which the system is shut down, and the control device 60, the control power source 54, the auxiliary power source 55, etc. are operating, but the auxiliary devices are not operating. . If the system is in a standby state and is prohibited from being restarted, that state is maintained until the inspection / repair is performed, and the system is not started or operated for power generation.

  Next, the case where it is determined that the temperature of the exhaust heat recovery system is abnormal will be described with reference to FIG. When a start switch (not shown) is turned on, the control device 60 starts executing a program corresponding to the flowchart shown in FIG. The control device 60 repeatedly executes the determination in step 402 until it is determined that the temperature of the exhaust heat recovery system is abnormal. When it is determined that the temperature of the exhaust heat recovery system is abnormal, the control device 60 determines “YES” in step 302, advances the program to step 404, and counts up the number of error occurrences. The number of occurrences of errors indicates the number of times that a temperature abnormality has occurred in the exhaust heat recovery system.

  In step 406, the control device 60 determines whether or not the system stop operation process started in another flowchart has been completed. The control device 60 repeatedly executes the determination in step 406 until the system stop operation process is completed. When it is determined that the system stop operation process has been completed, the control device 60 determines “YES” in step 406 and advances the program to step 408.

  In step 408, the control device 60 determines whether or not the number of error occurrences counted up first is equal to or greater than a predetermined value n. When the error occurrence count is smaller than the predetermined value n, the control device 60 advances the program to step 410, and the temperature of the hot water supplied from the heat exchanger 33 to the hot water tank 31 is sufficiently lowered (cooled). Confirm that this is the case and restart the system.

  Specifically, in step 410, control device 60 reads stored hot water temperature Th1 in the vicinity of power shutoff device 56 from temperature sensor 32c, and determines whether or not read temperature Th1 is equal to or lower than determination temperature ThH. When the temperature Th1 is equal to or lower than the determination temperature ThH, the temperature of the hot water supplied from the heat exchanger 33 to the hot water tank 31 is sufficiently lowered. The determination is made and the system is restarted as in step 308 (step 412). On the other hand, when temperature Th1 is higher than determination temperature ThH, control device 60 determines “NO” in step 410 and advances the program to step 411. When the temperature Th1 is higher than the determination temperature ThH when a predetermined time has elapsed from the time when it is determined in step 411 that the number of error occurrences is smaller than the predetermined value n, the control device 60 restarts in the same manner as in step 312 above. A standby state is maintained until inspection and repair without permission (step 414). When the temperature Th1 is lower than the determination temperature ThH after the elapse of a predetermined time in step 411, the control device 60 restarts the system in the same manner as in step 308 (step 412).

  On the other hand, when the number of occurrences of the error is equal to or greater than the predetermined value n, that is, when the same abnormality is detected continuously n times, the control device 60 does not allow the restart as in the above step 312 until the inspection and repair. The standby state is maintained (step 414).

  Instead of the process in step 410, it may be determined whether the hot water stored in the hot water storage tank 31 is hot and full. For example, the hot water storage tank 31 is detected by communication with a temperature sensor group (not shown) provided in the hot water tank 31 that the hot water stored at a high temperature (predetermined temperature (for example, 75 ° C. or higher)) is not full. That's fine. Further, instead of the process of step 410, it may be determined whether or not the temperature of the hot water supplied from the hot water storage tank 31 to the heat exchanger 33 has been sufficiently lowered (cooled). For example, the temperature of the stored hot water may be detected by the temperature sensor 32b.

  As is clear from the above description, in the present embodiment, in the fuel cell system, when the temperature of the hot water becomes equal to or higher than the predetermined operating temperature, the power shut-off device 56 drives the drive voltage from the auxiliary power source 55. Can be cut off from the power supply circuit 57 supplying the auxiliary equipment. Therefore, the power shut-off device 56 can be provided as a safety device for stopping the fuel cell system when the exhaust heat recovery system becomes abnormal (for example, when the stored hot water becomes high temperature). Further, the determination means (control device 60; flowchart shown in FIG. 4 or FIG. 6) includes a hot water storage detected by the output voltage V of the auxiliary power source 55 detected by the voltage detection device (voltage sensor 55a) and the temperature sensor 32c. It is determined from the water temperature which of the auxiliary power source 55 and the exhaust heat recovery system is abnormal. Thereby, when the fuel cell system is configured to stop operation by stopping the supply of the power supply voltage to the auxiliary machine, whether the supply of the power supply voltage is stopped due to an abnormality of the auxiliary power supply 55, It is possible to accurately determine whether the supply of the power supply voltage has been stopped due to an abnormality in the exhaust heat recovery system, that is, where the abnormality has occurred.

  Therefore, in the fuel cell system, when the power supply voltage of the auxiliary machine decreases, the power generation operation (steady operation) and the start operation cannot be continued, and the system is stopped. At that time, it is possible to determine whether the auxiliary power supply 55 is abnormal or the exhaust heat recovery water system is abnormal (high temperature), so that the location of the failure can be identified, and the response (inspection / repair) can be performed quickly. Can do.

  In addition, the power shut-off device 56 includes a heat sensitive part 56b that senses the temperature of the hot water storage and deforms according to the temperature change, and a switch part 56d that communicates and shuts off the power circuit 57 according to the deformation of the heat sensitive part 56b. The temperature sensor 32c is provided with an abnormality occurrence location by directly detecting the actual shutoff operation temperature of the power shutoff device 56 in order to detect the temperature of the hot water stored in the heat shutoff unit 56b of the power shutoff device 56. Can be determined more accurately.

  Further, the determination means is configured such that the output voltage V of the auxiliary power source 55 detected by the voltage detection device (voltage sensor 55a) is equal to or lower than the predetermined voltage VL, and the temperature Th1 of the hot water detected by the temperature sensor 32c. Is less than the predetermined temperature ThU, it is determined that the auxiliary power supply is abnormal (step 114). Thereby, it can be accurately determined that the auxiliary power supply 55 is abnormal.

  Further, the determination means is configured such that the output voltage V of the auxiliary power source 55 detected by the voltage detection device (voltage sensor 55a) is equal to or lower than the predetermined voltage VL, and the temperature Th1 of the hot water detected by the temperature sensor 32c. Is greater than or equal to a predetermined temperature ThU, it is determined that the exhaust heat recovery system is abnormal (step 112). Thereby, it can be determined accurately that the exhaust heat recovery system is abnormal.

  Further, the determination means is configured such that the output voltage V of the auxiliary power source 55 detected by the voltage detection device (voltage sensor 55a) is equal to or lower than the predetermined voltage VL, and the temperature Th1 of the hot water detected by the temperature sensor 32c. When the temperature is equal to or higher than the predetermined temperature ThU continues for the first predetermined time TM1, it is determined that the exhaust heat recovery system is abnormal (step 210). This makes it possible to accurately and accurately determine that the exhaust heat recovery system is abnormal.

  Further, the determination means is configured such that the output voltage V of the auxiliary power source 55 detected by the voltage detection device (voltage sensor 55a) is equal to or lower than the predetermined voltage VL, and the temperature Th1 of the hot water detected by the temperature sensor 32c. Is lower than the predetermined temperature ThU for a second predetermined time TM2 longer than the first predetermined time TM1, it is determined that the auxiliary power supply 55 is abnormal. As a result, it is possible to accurately and accurately determine that the auxiliary power supply 55 is abnormal. In addition, since the abnormality of the exhaust heat recovery system can be detected first and then the failure of the auxiliary power supply 55 can be detected, it is possible to clearly distinguish between any abnormality and failure.

  In the above-described embodiment, the temperature of the stored hot water detected by the temperature sensor 32d may be used instead of the temperature of the stored hot water detected by the temperature sensor 32c in the processing of step 108 or the like.

  DESCRIPTION OF SYMBOLS 11 ... Housing, 11a ... 1st exhaust port, 11b ... Air outlet port, 11c ... Air inlet port, 12 ... Partition member, 12a ... Air inlet port, 13 ... Water tank, 14 ... Pure water device, 15 ... For ventilation Air blower, 20 ... Fuel cell module, 21 ... Casing, 21a ... Exhaust port, 22 ... Evaporating part, 23 ... Reforming part, 24 ... Fuel cell, 24a ... Cell, 24b ... Fuel flow path, 24c ... Air flow path, 25 ... Manifold, 30 ... Waste heat recovery system (exhaust heat recovery system), 31 ... Hot water tank, 32 ... Hot water circulation line, 32a ... Hot water circulation pump, 32b, 32c, 32d ... Temperature sensor, 33 ... Heat exchanger, 50 Inverter device, 51: System power supply, 52 ... Power supply line, 53 ... External power load, 54 ... Power supply for control, 55 ... Power supply for auxiliary equipment, 55a ... Voltage detection device, 56 ... Power supply shut-off device, 56b ... Heat sensitive part, 56d Switch section, 57 ... power supply circuit, 60 ... control device R1 ... first chamber, R2 ... second chamber.

Claims (5)

A fuel cell that generates electricity using fuel and oxidant gas;
An exhaust heat recovery system for recovering and storing the exhaust heat in the hot water by exchanging heat between the exhaust heat of the fuel cell and the hot water;
An auxiliary power source for supplying a driving voltage to an auxiliary device for supplying the fuel, the oxidant gas and the hot water,
A power cut-off device provided in a power supply circuit that supplies the drive voltage from the auxiliary power supply to the auxiliary machine and that communicates and cuts off the power supply circuit according to the temperature of the hot water;
A voltage detection device for detecting an output voltage of the auxiliary power supply;
A temperature sensor for detecting the temperature of the hot water,
A control device for controlling supply of the fuel, the oxidant gas, and the hot water;
With
The power shut-off device includes a heat-sensitive part that senses the temperature of the hot water storage and deforms according to the temperature, and a switch part that communicates and shuts off the power circuit according to the deformation of the heat-sensitive part.
The temperature sensor detects a temperature of the hot water sensed by a heat sensitive part of the power shut-off device,
From the output voltage of the auxiliary power source detected by the voltage detection device and the temperature of the hot water detected by the temperature sensor, the control device determines which one of the auxiliary power source and the exhaust heat recovery system is A fuel cell system comprising determination means for determining whether or not there is an abnormality. 2. The determination unit according to claim 1 , wherein an output voltage of the auxiliary power source detected by the voltage detection device is equal to or lower than a predetermined voltage, and a temperature of the hot water detected by the temperature sensor is a predetermined temperature. A fuel cell system that determines that the auxiliary power supply is abnormal when the power is less than 2. The determination unit according to claim 1 , wherein an output voltage of the auxiliary power source detected by the voltage detection device is equal to or lower than a predetermined voltage, and a temperature of the hot water detected by the temperature sensor is a predetermined temperature. A fuel cell system that determines that the exhaust heat recovery system is abnormal when the above is true. 2. The determination unit according to claim 1 , wherein an output voltage of the auxiliary power source detected by the voltage detection device is equal to or lower than a predetermined voltage, and a temperature of the hot water detected by the temperature sensor is a predetermined temperature. A fuel cell system that determines that the exhaust heat recovery system is abnormal when the above state continues for a first predetermined time. 2. The determination unit according to claim 1, wherein an output voltage of the auxiliary power source detected by the voltage detection device is equal to or lower than a predetermined voltage, and a temperature of the hot water detected by the temperature sensor is a predetermined temperature. The fuel cell system that determines that the power supply for auxiliary equipment is abnormal when the state of being less than is continued for a second predetermined time.

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