JP2019129021A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system which is advantageous in preventing freezing when there is an abnormality in a water path. A fuel cell system (1a) of the present disclosure includes a fuel cell (10), a first tank (21), a first water path (31), a reformer (11), and a second tank. (22), a second water path (32), a third water path (33), a heater (40), a housing (50), and a controller (60). The heater (40) is arranged inside the first tank (21). The controller (60) may freeze at least one of the first water path (31), the second water path (32), and the third water path (33), and the first water path (31). And when it is determined that at least one of the second water paths (32) is abnormal, the heater (40) is caused to generate heat with the second output higher than the first output. The internal space of the housing (50) is warmed up by the heat radiation from the first tank (21). [Selection diagram] Figure 1

Description

  The present disclosure relates to a fuel cell system.

  Conventionally, in a fuel cell system, water is used for fuel reforming, and the fuel cell is sometimes cooled using cooling water. For this reason, when the fuel cell system is installed at a low temperature location, water may be frozen, and a fuel cell system applicable to cold regions has been proposed.

  For example, Patent Document 1 describes a fuel cell system including a heating unit that heats the internal space of a housing. The heating means is disposed on the bottom surface side of the casing, and heat from the heating means can be naturally convected to the entire internal space of the casing. The heating means is, for example, a sheathed heater.

International Publication No. 2009/034997 (Figure 2)

  According to the technique described in Patent Literature 1, no consideration has been given to freeze prevention processing when there is an abnormality in the water path of the fuel cell system. Therefore, the present disclosure provides a fuel cell system that is advantageous from the viewpoint of preventing freezing of the water path when the water path of the fuel cell system is abnormal.

The present disclosure
A fuel cell;
A first tank for storing water for recovering heat generated by the fuel cell;
A first water path through which water circulating between the fuel cell and the first tank flows;
A reformer that generates the fuel gas from raw material gas and water;
A second tank for storing water to be supplied to the reformer;
A branch point that connects the second tank, the reformer, and the first tank, and branches off the flow of water supplied to the reformer and the flow of water supplied to the first tank. A second water path,
A first on-off valve disposed between the branch point and the reformer in the second water path;
A third water path for leading water overflowing from the first tank to the second tank;
A heater disposed inside the first tank;
A first water supplier that is disposed in the first water path and circulates water between the fuel cell and the first tank;
A second water supplier that is disposed in the second water path and sends water stored in the second tank to at least one of the reformer and the first tank;
A housing for housing the fuel cell, the first tank, the first water path, the reformer, the second tank, the second water path, and the third water path;
And a controller,
The controller may cause at least one of the first water path, the second water path, and the third water path to freeze, and at least one of the first water path and the second water path. From the first output of the heater for preventing freezing of the first water path and the second water path when the first water path and the second water path are normal. Heat the heater with a high second output and heat the internal space of the housing by heat radiation from the first tank,
Provide a fuel cell system.

  The fuel cell system of the present disclosure is advantageous for preventing freezing of the water path when there is an abnormality in the water path.

FIG. 1 is a configuration diagram illustrating an example of a fuel cell system according to the present disclosure. FIG. 2 is a flowchart showing an example of the antifreeze processing of the fuel cell system of the present disclosure. FIG. 3 is a flowchart showing an example of the antifreeze processing of the fuel cell system of the present disclosure. FIG. 4 is a configuration diagram illustrating another example of the fuel cell system according to the present disclosure. FIG. 5 is a flowchart showing another example of the antifreeze processing of the fuel cell system of the present disclosure. FIG. 6 is a configuration diagram showing still another example of the fuel cell system of the present disclosure. FIG. 7 is a flowchart illustrating still another example of the freeze prevention process of the fuel cell system according to the present disclosure. FIG. 8 is a flowchart illustrating yet another example of the freeze prevention process of the fuel cell system according to the present disclosure. FIG. 9 is a configuration diagram illustrating still another example of the fuel cell system according to the present disclosure. FIG. 10 is a flowchart illustrating yet another example of the freeze prevention process of the fuel cell system according to the present disclosure.

(Knowledge that became the basis of this disclosure)
When there is a possibility that the water path is frozen in the fuel cell system, the processing for preventing freezing is not limited to heating the heater disposed on the bottom side of the casing. For example, it is also conceivable to realize freeze prevention by operating a water supply device such as a pump arranged in the water path to move water in the water path. In addition, it is also conceivable that the water stored in the tank is heated by a heater disposed inside the tank, and the water inside the tank heated by the heater is caused to flow through the water path by operating the water supply device. However, in a fuel cell system that operates the water supply device to prevent the water channel from freezing, there is a possibility that the water channel may not be properly frozen if there is an abnormality in the water channel due to a failure of the water supply device. is there. Therefore, the present inventors have repeatedly studied day and night on a technique that can prevent freezing of the water path even when there is an abnormality in the water path, and devised the fuel cell system of the present disclosure. In addition, the present inventors have also devised a fuel cell system that can prevent the water path from freezing when the heater disposed inside the tank has an abnormality.

The fuel cell system according to the first aspect of the present disclosure includes:
A fuel cell;
A first tank for storing water for recovering heat generated by the fuel cell;
A first water path through which water circulating between the fuel cell and the first tank flows;
A reformer for generating the fuel gas from a raw material gas and water;
A second tank for storing water to be supplied to the reformer;
The second tank communicates with the reformer and the first tank, and has a branch point where the flow of water supplied to the reformer and the flow of water supplied to the first tank branch. A second water path,
A first on-off valve disposed between the branch point and the reformer in the second water path;
A third water path for leading water overflowing from the first tank to the second tank;
A heater disposed inside the first tank;
A first water supplier that is disposed in the first water path and circulates water between the fuel cell and the first tank;
A second water supplier that is disposed in the second water path and sends water stored in the second tank to at least one of the reformer and the first tank;
A housing for housing the fuel cell, the first tank, the first water path, the reformer, the second tank, the second water path, and the third water path;
And a controller,
The controller may cause at least one of the first water path, the second water path, and the third water path to freeze, and at least one of the first water path and the second water path. From the first output of the heater for preventing freezing of the first water path and the second water path when the first water path and the second water path are normal. The heater is heated with a high second output, and the internal space of the housing is warmed by heat radiation from the first tank.

  According to the first aspect of the present disclosure, at least one of the first water path, the second water path, and the third water path may freeze, and at least one of the first water path and the second water path is abnormal. When there is, the heater generates heat with the second output. Since the heater generates heat at a high output, the heat radiation from the first tank in which the water heated by the heater is stored extends over a wide range of the internal space of the housing. Thereby, even if there is an abnormality in at least one of the first water path and the second water path, freezing of the first water path, the second water path, and the third water path can be advantageously prevented. In the technique described in Patent Document 1, the heating means does not necessarily heat the water stored in the tank.

  In the second aspect of the present disclosure, for example, in the fuel cell system according to the first aspect, the temperature of the air inside the casing or outside the casing, or the first water path, the second water path, and the The system further comprises a temperature sensor for detecting the temperature of water in at least one of the third water paths, wherein the controller detects that the temperature sensor is below the first temperature, the first water path, It is determined that at least one of the second water path and the third water path may freeze. According to the second aspect, the controller can appropriately determine that at least one of the first water path, the second water path, and the third water path may freeze based on the detection result by the temperature sensor. .

  In the third aspect of the present disclosure, for example, in the fuel cell system according to the first aspect or the second aspect, the controller includes at least one of the first water path, the second water path, and the third water path. When the first water path is abnormal and the second water path is normal, the heater generates heat with the second output, and the first water path The on-off valve is closed to inhibit the operation of the first water supplier while operating the second water supplier. According to the third aspect, since the heater generates heat with high output and the water heated by the heater flows through the second water path without being supplied to the reformer, a wide range of the internal space of the housing is efficient. Warm up to. As a result, even if there is an abnormality in the first water path, freezing of the first water path, the second water path, and the third water path can be advantageously prevented.

  In the fourth aspect of the present disclosure, for example, in the fuel cell system according to any one of the first to third aspects, the controller determines that the abnormality of the first water supply is an abnormality of the first water path. to decide. According to the fourth aspect, by monitoring the first water supplier, it is possible to determine the presence or absence of an abnormality in the first water path.

  In the fifth aspect of the present disclosure, for example, in the fuel cell system according to any one of the first to fourth aspects, the controller includes the first water path, the second water path, and the third water path. When it is determined that at least one of the water paths may freeze and the second water path is abnormal and the first water path is normal, the heater generates heat at the second output, And prohibiting the operation of the second water supplier while operating the first water supplier. According to the fifth aspect, since the heater generates heat with high output and the water heated by the heater flows through the first water path, a wide range of the internal space of the housing is efficiently warmed. As a result, even if there is an abnormality in the second water path, freezing of the first water path, the second water path, and the third water path can be advantageously prevented.

  In the sixth aspect of the present disclosure, for example, in the fuel cell system according to any one of the first to fifth aspects, the controller includes an abnormality in the second water supply device and an abnormality in the first on-off valve. Is determined as an abnormality in the second water path. According to the sixth aspect, it is possible to determine whether there is an abnormality in the second water path by monitoring the second water supply device and the first on-off valve.

  In the seventh aspect of the present disclosure, for example, in the fuel cell system according to any one of the first aspect to the sixth aspect, the second water supply unit is configured to transmit the reformer and the first from the second tank. It is operable by switching between a first mode of supplying water toward at least one of the tanks and a second mode of flowing back water toward the second tank in the second water path. In addition, in the seventh aspect, in the fuel cell system according to any one of the first to sixth aspects, the controller includes the first water path, the second water path, and the third water path. The second water supply device is operated in the second mode to discharge water from the second water path when it is determined that at least one of them may freeze and the heater is abnormal. . According to the seventh aspect, when it is determined that the heater is abnormal, the second water supplier operates in the second mode to discharge water from the second water path. Thereby, freezing of the 2nd water course can be prevented advantageously.

  In the eighth aspect of the present disclosure, for example, the fuel cell system according to any one of the first aspect to the sixth aspect includes a bypass path that bypasses the second water supplier in the second water path, and the bypass And a second on-off valve disposed in the path, wherein the controller closes the second on-off valve when the fuel cell is generating electricity, and the first water path, the second water path, and When it is determined that at least one of the third water paths may freeze and the heater has an abnormality, the second on-off valve is opened to discharge water from the second water path. According to the eighth aspect, when it is determined that there is an abnormality in the heater, the second on-off valve is opened and water is discharged from the second water path. Thereby, freezing of the 2nd water course can be prevented advantageously.

  In the ninth aspect of the present disclosure, for example, the fuel cell system according to any one of the first to eighth aspects further includes a fan that circulates air inside the housing, and the controller includes the controller The fan is operated when the heater generates heat with the second output. According to the ninth aspect, the heat dissipated from the first tank is carried by the flow of air generated by the fan, and a wide range of the internal space of the housing is efficiently warmed. As a result, when there is an abnormality in at least one of the first water path and the second water path, freezing of the first water path, the second water path, and the third water path can be advantageously prevented.

A fuel cell system according to a tenth aspect of the present disclosure includes:
A fuel cell;
A reformer for generating the fuel gas from a raw material gas and water;
A tank for storing water to be supplied to the reformer;
A water path through which water supplied to the reformer flows;
A heater disposed inside the tank;
A water supplier, disposed in the water path, for sending the water stored in the tank to the reformer;
A housing for housing the fuel cell, the reformer, the tank, and the water path;
And a controller,
When the controller determines that there is a possibility that the water path is frozen and that the water path is abnormal, the controller controls the heater for preventing the water path from freezing when the water path is normal. The heater is heated with a second output higher than the first output, and the internal space of the housing is warmed by heat radiation from the tank.

  According to the tenth aspect, the heater generates heat with the second output when there is a possibility that the water path is frozen and there is an abnormality in the water path. Since the heater generates heat at a high output, the heat radiation from the tank in which the water heated by the heater is stored extends over a wide range of the internal space of the housing. Thereby, even if there is an abnormality in the water path, freezing of the water path can be advantageously prevented.

  In an eleventh aspect of the present disclosure, for example, the fuel cell system according to the tenth aspect further includes a temperature sensor that detects a temperature of air inside the casing or outside the casing, or a temperature of water in the water path. The controller determines that the water path may freeze when the temperature sensor detects that the temperature is lower than the first temperature. According to the eleventh aspect, the controller can appropriately determine that the water path may be frozen based on the detection result by the temperature sensor.

  In a twelfth aspect of the present disclosure, for example, in the fuel cell system according to the tenth aspect or the eleventh aspect, the controller determines an abnormality of the water supply device as an abnormality of the water path. According to the twelfth aspect, by monitoring the water supply device, it is possible to determine the presence or absence of an abnormality in the water path.

  In the thirteenth aspect of the present disclosure, for example, in the fuel cell system according to any one of the tenth to twelfth aspects, the water supply unit supplies water from the tank toward the reformer. It is operable by switching between one mode and a second mode in which water is reversely flowed back to the tank in the water path, the controller may freeze the water path, and the heater is abnormal. When it is determined that the water supply device is operated in the second mode to discharge water from the water path. According to the thirteenth aspect, when it is determined that there is an abnormality in the heater, the water supply device operates in the second mode and water is discharged from the water path. Thereby, freezing of a water path can be prevented advantageously.

  In the fourteenth aspect of the present disclosure, for example, the fuel cell system according to any one of the tenth aspect to the thirteenth aspect is disposed in a bypass path that bypasses the water supply unit in the water path, and the bypass path. The controller further includes: the controller, when the fuel cell is generating electricity, closes the on-off valve and may freeze the water path, and determine that the heater has an abnormality Occasionally, the on-off valve is opened to drain water from the water path. According to the fourteenth aspect, when it is determined that the heater is abnormal, the on-off valve is opened and water is discharged from the water path. Thereby, freezing of a water path can be prevented advantageously.

  In the fifteenth aspect of the present disclosure, for example, the fuel cell system according to any one of the tenth to fourteenth aspects further includes a fan that circulates air inside the housing, and the controller includes the controller The fan is operated when the heater generates heat with the second output. According to the fifteenth aspect, the heat dissipated from the tank is carried by the flow of air generated by the fan, and a wide range of the internal space of the housing is efficiently warmed. As a result, when there is an abnormality in the water path, freezing of the water path can be advantageously prevented.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

First Embodiment
As shown in FIG. 1, the fuel cell system 1 a includes a fuel cell 10, a first tank 21, a first water path 31, a reformer 11, a second tank 22, a second water path 32, A first on-off valve 36 and a third water path 33 are provided. In addition, the fuel cell system 1 a includes a heater 40, a first water supplier 35, a second water supplier 37, a casing 50, and a controller 60. The fuel cell 10 generates electricity by reacting a fuel gas containing hydrogen and an oxidant gas. The first tank 21 stores water for recovering the heat generated by the fuel cell 10. Water circulating between the fuel cell 10 and the first tank 21 flows through the first water path 31. The reformer 11 generates a fuel gas from the raw material gas and water. The second tank 22 stores water to be supplied to the reformer 11. The second water path 32 connects the second tank 22 with the reformer 11 and the first tank 21, and the flow of water supplied to the reformer 11 and the flow of water supplied to the first tank 21. Has a branch point BP that branches. The first on-off valve 36 is disposed between the branch point BP and the reformer 11 in the second water path 32. The third water path 33 leads the water overflowed from the first tank 21 to the second tank 22. The heater 40 is disposed inside the first tank 21. The first water supply unit 35 is disposed in the first water path 31 and circulates water between the fuel cell 10 and the first tank 21. The second water supply unit 37 is disposed in the second water path 32 and sends the water stored in the second tank 22 to at least one of the reformer 11 and the first tank 21. The housing 50 houses the fuel cell 10, the first tank 21, the first water path 31, the reformer 11, the second tank 22, the second water path 32, and the third water path 33. The controller 60 may freeze at least one of the first water path 31, the second water path 32, and the third water path 33, and at least one of the first water path 31 and the second water path 32. When it is determined that there is an abnormality, the heater 40 is heated at the second output. Thereby, the internal space of the housing 50 is warmed up by the heat radiation from the first tank 21. The second output is higher than the first output of the heater 40 for preventing freezing of the first water path 31 and the second water path 32 when the first water path 31 and the second water path 32 are normal.

  When the controller 60 makes the above determination, the heater 40 generates heat at the second output, so the water stored in the first tank 21 is heated to a higher temperature than when the normal antifreeze treatment is performed. The For this reason, the heat radiation from the first tank 21 in which the water heated by the heater 40 is stored extends over a wide range of the internal space of the housing 50. Thereby, there is an abnormality in at least one of the first water path 31 and the second water path 32, and the water heated by the heater 40 could not flow into at least one of the first water path 31 and the second water path 32. However, freezing of these water paths can be advantageously prevented. The second output of the heater 40 is not particularly limited as long as it is higher than the first output. For example, the temperature of the water stored in the first tank 21 can be kept at 70 ° C. or higher. The heater 40 is, for example, a resistance heating type electric heater. In addition, the 1st output of the heater 40 is defined so that the temperature of the water stored by the 1st tank 21 can be maintained at 30-50 degreeC, for example.

  As shown in FIG. 1, the fuel cell system 1a further includes a temperature sensor 65, for example. The temperature sensor 65 detects, for example, the temperature of air inside the housing 50. The temperature sensor 65 is disposed, for example, near the bottom surface of the housing 50. The temperature sensor 65 may detect the temperature of the air outside the housing 50 or the temperature of water in at least one of the first water path 31, the second water path 32, and the third water path 33. . For example, when the temperature sensor 65 detects that the temperature is lower than the first temperature T1, the controller 60 may freeze at least one of the first water path 31, the second water path 32, and the third water path 33. Judge that there is. The first temperature T1 is, for example, 0 ° C. As described above, the controller 60 appropriately uses the detection result of the temperature sensor 65 to appropriately indicate that at least one of the first water path 31, the second water path 32, and the third water path 33 may be frozen. It can be judged. The temperature sensor 65 is, for example, a temperature sensor using a thermistor or a temperature sensor using a thermocouple.

  For example, the controller 60 may freeze at least one of the first water path 31, the second water path 32, and the third water path 33, and there is an abnormality in the first water path 31 and the second water Assume that it is determined that the path 32 is normal. In this case, the controller 60 causes the heater 40 to generate heat at the second output. In addition, the controller 60 prohibits the operation of the first water supply device 35 while closing the first on-off valve 36 and operating the second water supply device 37. In this case, the heater 40 generates heat with the second output, and the water heated by the heater 40 flows through the second water path 32 without being supplied to the reformer 11. Thereby, even if the wide range of the internal space of the housing | casing 50 heats efficiently and there is abnormality in the 1st water path 31, the 1st water path 31, the 2nd water path 32, and the 3rd water path 33 of Freezing can be advantageously prevented.

  For example, the controller 60 determines that an abnormality in the first water supply unit 35 is an abnormality in the first water path 31. For example, the controller 60 acquires information indicating the operating state of the first water supply device 35 and determines whether or not the first water supply device 35 is abnormal.

  For example, the controller 60 may freeze at least one of the first water path 31, the second water path 32, and the third water path 33, and the second water path 32 has an abnormality and the first water Assume that it is determined that the path 31 is normal. In this case, the controller 60 generates heat with the second output. In addition, the controller 60 prohibits the operation of the second water supply device 37 while operating the first water supply device 35. In this case, the heater 40 generates heat at the second output and the water heated by the heater 40 flows through the first water path 31 so that the wide range of the internal space of the housing 50 is efficient. Warm up. As a result, even if there is an abnormality in the second water path 32, freezing of the first water path 31, the second water path 32, and the third water path 33 can be advantageously prevented.

  For example, the controller 60 determines that at least one of the abnormality of the second water supply device 37 and the abnormality of the first on-off valve 36 is an abnormality of the second water passage 32. For example, the controller 60 acquires information indicating the operating state of the second water supply device 37 and determines whether or not the second water supply device 37 is abnormal. Further, the controller 60 detects an abnormality of the first on-off valve 36 based on information indicating a detection result of a temperature sensor or a flow meter affected by the detection result due to an abnormality of the first on-off valve 36, for example. The first on-off valve 36 is, for example, an electromagnetic valve.

  Each of the first water supplier 35 and the second water supplier 37 is, for example, a positive displacement pump such as a piston pump, a plunger pump, a gear pump, or a vane pump. The second water supplier 37 is operable, for example, by switching between the first mode and the second mode. The first mode is a mode in which water is supplied from the second tank 22 toward at least one of the reformer 11 and the first tank 21. The second mode is a mode in which water flows backward toward the second tank 22 in the second water path 32. In this case, the second water supplier 37 includes, for example, a pump mechanism operated by a motor capable of rotating in the forward and reverse directions. The motor is, for example, a stepping motor. For example, it is assumed that the controller 60 determines that at least one of the first water path 31, the second water path 32, and the third water path 33 may freeze and the heater 40 has an abnormality. In this case, the controller 60 operates the second water supplier 37 in the second mode to discharge water from the second water path 32. Thereby, even when the heater 40 has an abnormality, the freezing of the second water passage 32 can be advantageously prevented. When the second water supplier 37 is operable by switching between the first mode and the second mode, the second water supplier 37 operates in the first mode unless otherwise described. For example, the controller 60 determines that the heater 40 is abnormal when acquiring information indicating that the value of the current flowing through the heater 40 is abnormal. The controller 60 may determine whether or not the heater 40 is normal based on the rising temperature of the water temperature of the first tank 21 during a predetermined period after sending a control signal for causing the heater 40 to generate heat.

  As shown in FIG. 1, the fuel cell system 1 a further includes, for example, a fan 80. For example, the controller 60 operates the fan 80 when the heater 40 generates heat with the second output. In this case, the heat dissipated from the first tank 21 is carried by the air flow generated by the fan 80, and the wide range of the internal space of the housing 50 is efficiently warmed. As a result, when there is an abnormality in at least one of the first water path 31 and the second water path 32, freezing of the first water path 31, the second water path 32, and the third water path 33 can be advantageously prevented. .

  In the internal space of the housing 50, for example, the fan 80 flows near the first water path 31 after the air flow generated by the operation of the fan 80 passes near the first tank 21, and It arrange | positions so that the vicinity of the 2nd water path 32 may be passed. Thereby, freezing of the 1st water path 31 and the 2nd water path 32 can be prevented more certainly.

The reformer 11 generates hydrogen by a reforming reaction such as a steam reforming reaction (CH ₄ + H ₂ O → CO + 3H ₂ ), for example. The reformer 11 contains a reforming catalyst for advancing the reforming reaction. The reformer 11 also contains a catalyst for removing carbon monoxide. Catalysts for removing carbon monoxide include CO shift catalyst and CO selective oxidation removal catalyst. For example, a hydrocarbon gas such as city gas or LP gas (liquefied petroleum gas) is supplied to the reformer 11 as a raw material gas. The fuel gas containing hydrogen generated by the reformer 11 is supplied to the fuel cell 10. The fuel cell 10 is, for example, a polymer electrolyte fuel cell or a solid oxide fuel cell.

  The fuel cell system 1 a further includes a fuel gas supply path 12, an oxidant gas supply path 16, an anode offgas path 14, and a cathode offgas path 18. The fuel gas supply path 12 is a flow path for supplying fuel gas from the reformer 11 to the fuel cell 10. The fuel gas supply path 12 connects the reformer 11 and the anode gas inlet of the fuel cell 10. The oxidant gas supply path 16 is a flow path for supplying air as an oxidant gas to the cathode of the fuel cell 10. An air supplier 15 is provided in the oxidant gas supply path 16. The air supplier 15 is a device for supplying air to the fuel cell 10. The air supply unit 15 is, for example, a fan or a blower. Other devices such as a humidifier and a valve may be disposed in the oxidant gas supply path 16. The anode off-gas path 14 is a flow path for discharging unreacted fuel gas and unreacted raw material gas from the anode of the fuel cell 10. The anode off-gas path 14 connects the anode gas outlet of the fuel cell 10 and the combustor 13 disposed inside the reformer 11. The unreacted hydrogen and the unreacted feed gas are supplied to the combustor 13 through the anode off gas passage 14. The cathode off-gas path 18 is a flow path for discharging unreacted oxidant gas from the cathode of the fuel cell 10. The cathode off gas path 18 is connected to the cathode gas outlet of the fuel cell 10 and extends to the outside of the housing 50, for example.

  For example, a temperature sensor 23 is provided in the first tank 21. The temperature sensor 23 is disposed inside the first tank 21 and detects the temperature of the water stored in the first tank 21. The temperature sensor 23 is, for example, a temperature sensor using a thermistor or a temperature sensor using a thermocouple. For example, the heater 40 is controlled so that the water temperature of the first tank 21 falls within a predetermined temperature range.

  The first water path 31 has, for example, a feed path 31a and a return path 31b. The feed path 31 a and the return path 31 b respectively connect the fuel cell 10 and the first tank 21. The water stored in the first tank 21 is supplied to the fuel cell 10 as cooling water through the feed path 31a. Water is returned from the fuel cell 10 to the first tank 21 through the return path 31b. The first water supplier 35 is disposed, for example, in the feed path 31 a. The first water supplier 35 may be disposed in the return path 31 b.

  The fuel cell system 1a further includes, for example, a heat recovery path 70 and a heat exchanger 75. The heat exchanger 75 is disposed in the first water path 31. The heat exchanger 75 is arrange | positioned at the feed path 31a, for example. The heat exchanger 75 is, for example, a liquid-liquid heat exchanger such as a double pipe heat exchanger or a plate heat exchanger.

  The heat recovery path 70 is a flow path for recovering the exhaust heat of the fuel cell 10. The heat recovery path 70 includes a feed path 71 and a return path 72. The feed path 71 and the return path 72 are each connected to the heat exchanger 75. The feed path 71 constitutes an upstream portion of the heat recovery path 70. The return path 72 constitutes a downstream portion of the heat recovery path 70. The return path 72 is a flow path for leading the water heated in the heat exchanger 75 to a hot water storage tank (not shown). The feed path 71 is a flow path for leading the water to be heated in the heat exchanger 75 to the heat exchanger 75. The heat exchanger 75 is configured to exchange heat between the water flowing through the heat recovery path 70 and the water flowing through the first water path 31. That is, the heat exchanger 75 plays a role of heating water to be stored in the hot water storage tank (not shown) by the heat of the cooling water in the first water passage 31.

  For example, a third water supplier 73 is disposed in the heat recovery path 70. The 3rd water supply device 73 is arrange | positioned at the feed path 71, for example. The third water supplier 73 may be disposed in the return path 72. The third water supplier 73 is, for example, one of the positive displacement pumps described above.

  For example, a temperature sensor 24 is provided in the second tank 22. The temperature sensor 24 is disposed inside the second tank 22 and detects the temperature of the water stored in the second tank 22. The temperature sensor 24 is, for example, a temperature sensor using a thermistor or a temperature sensor using a thermocouple. In the second tank 22, for example, condensed water generated from the cathode off gas and condensed water generated from the combustion exhaust gas are also collected and stored. Excess water overflows from the second tank 22 and is discharged outside the housing 50, for example.

  For example, the second water supply unit 37 is disposed between the second tank 22 and the branch point BP in the second water path 32. For example, an on-off valve 39 is disposed in the second water path 32. The on-off valve 39 is, for example, an electromagnetic valve. The on-off valve 39 is disposed between the branch point BP and the first tank 21 in the second water path 32. When the first opening / closing valve 36 is closed and the opening / closing valve 39 is opened, the water stored in the second tank 22 is supplied to the first tank 21. On the other hand, when the first on-off valve 36 is opened and the on-off valve 39 is closed, the water stored in the second tank 22 is supplied to the reformer 11.

  The fuel cell system 1a includes a control panel 63, for example. The control panel 63 receives an input of operating conditions of the fuel cell system 1a, and displays the operating state of the fuel cell system 1a.

  The controller 60 is typically a digital computer in which a program for operating the fuel cell system 1a is stored so as to be executable. The controller 60 acquires information indicating the detection results of the temperature sensor 65, the temperature sensor 23, and the temperature sensor 24 and information indicating the operating condition input to the control panel 63. The controller 60 further acquires information indicating the detection result of another detection device (not shown) such as another temperature sensor, a flow meter, and a gas sensor, for example. Further, the controller 60 acquires, for example, information indicating the operating state of the first water supply unit 35, the second water supply unit 37, the third water supply unit 73, and the fan 80 and information indicating the current value in the heater 40. Do. Based on these information, the controller 60, the first water supply unit 35, the second water supply unit 37, the third water supply unit 73, the heater 40, the first on-off valve 36, the on-off valve 39, the fan 80, etc. Control the control target of Further, the controller 60 causes the control panel 63 to display information indicating the operating state of the fuel cell system 1a.

  Each path is composed of at least one pipe. The pipe may be a metal pipe such as a stainless steel pipe, or may be a resin pipe.

  The operation of the fuel cell system 1a will be described. The fuel cell system 1a can be operated mainly according to four operation cycles of a startup period, a power generation period, a stop period, and a standby period. The "startup period" is an operation period for starting up the fuel cell system 1a. Specifically, the “startup period” is an operation period for gradually increasing the output of the fuel cell system 1a to a predetermined rated output (for example, 750 W). In the start-up period, the supply flow rate of the raw material gas to the reformer 11 and the supply flow rate of water are gradually increased. During the start-up period, the flow rate of the oxidant gas and the flow rate of the fuel gas gradually increase. The "power generation period" is a period in which the fuel cell system 1a is operated at a predetermined rated output. However, it is not essential that the fuel cell system 1a is always operated at the rated output during the power generation period. A period during which the fuel cell system 1a is stably operated with a constant output is a "power generation period". During the power generation period, the supply flow rate of the raw material gas to the reformer 11 and the supply flow rate of water are kept constant. The flow rate of the oxidant gas and the flow rate of the fuel gas are also kept constant. The "stop period" is an operation period for stopping the fuel cell system 1a. Specifically, the “stop period” is an operation period for gradually reducing the output of the fuel cell system 1a to zero. In the stop period, the supply flow rate of the source gas to the reformer 11 and the supply flow rate of water are gradually reduced. In the stop period, the flow rate of the oxidant gas and the flow rate of the fuel gas gradually decrease. The "standby period" is a period during which the output of the fuel cell system 1a is maintained at zero. In the standby period, the supply flow rate of the raw material gas to the reformer 11 and the supply flow rate of water are basically zero. However, in order to suppress deterioration of the reformer 11, the reformer 11 may be periodically purged with a raw material gas. During the standby period, the production of the fuel gas in the reformer 11 is stopped, and the flow rate of the oxidant gas and the flow rate of the fuel gas are basically zero. The controller 60 continues to execute a predetermined electrical process during the standby period. An example of such an electrical treatment is a treatment to monitor the amount of hot water in a hot water storage tank.

  In the start-up period and the stop period, the output of the fuel cell system 1a is, for example, rising or falling at a continuous and constant rate. However, the output of the fuel cell system 1a may be increased or decreased stepwise. Furthermore, the rate of increase or decrease in output may be changed.

  In one example, the lengths of the start and stop periods are each in the range of 10 minutes to 90 minutes. By spending sufficient time to start or stop the fuel cell system 1a, deterioration of the reformer 11, deterioration of the fuel cell 10, and the like can be suppressed. However, the fuel cell system 1a may be stopped instantaneously in an emergency such as when a sudden increase in the CO concentration in the combustion exhaust gas is detected.

  The length of the power generation period and the length of the standby period vary according to the time during which the fuel cell system 1a can be operated continuously, the capacity of the hot water storage tank, and the like. For example, when a sufficient amount of hot water is stored in the hot water storage tank, the fuel cell system 1a automatically stops operation and enters a standby period. When the amount of hot water in the hot water storage tank falls below the threshold, the fuel cell system 1a automatically starts operation. When the amount of hot water used is large, the waiting period may be zero in one operation cycle.

  In the start period, the power generation period, and the stop period, the first on-off valve 36 is opened, the on-off valve 39 is closed, and the second water supply unit 37 is operated. Thereby, the water of the second tank 22 is supplied to the reformer 11 through the second water passage 32. The raw material gas is supplied to the reformer 11 through a gas supply path (not shown).

  In the fuel cell system 1a, antifreeze processing is performed as needed during the standby period. An example of the antifreeze processing will be described with reference to FIGS. 2 and 3. As shown in FIG. 2, in step S1, the controller 60 acquires information indicating the detected temperature Ta of the temperature sensor 65, and determines whether Ta is equal to or less than the first temperature T1. If the determination result in step S1 is affirmative, the process proceeds to step S2, and the controller 60 determines whether or not the heater 40 is normal. For example, the controller 60 sends a control signal for causing the heater 40 to generate heat with a predetermined output, and then acquires information indicating the current value of the heater 40. The controller 60 determines that the heater 40 is normal when the information indicates a normal current value.

  When the determination result in step S2 is affirmative, the process proceeds to step S3, and the controller 60 determines whether or not the first water path 31 is normal. For example, if the first water supply unit 35 is normal, the controller 60 determines that the first water path 31 is normal. In this case, for example, the controller 60 operates the first water supply unit 35 to acquire information indicating the operation state of the first water supply unit 35, and if the operation state of the first water supply unit 35 is normal, The first water supply device 35 is determined to be normal.

  When the determination result in step S3 is affirmative, the process proceeds to step S4, and the controller 60 determines whether or not the second water path 32 is normal. For example, if the second water supply unit 37 and the first on-off valve 36 are normal, the controller 60 determines that the second water path 32 is normal. For example, the controller 60 operates the second water supply unit 37 to acquire information indicating the operation state of the second water supply unit 37, and if the operation state of the second water supply unit 37 is normal, the second It is determined that the water supply unit 37 is normal. For example, the controller 60 closes the first on-off valve 36 and opens the on-off valve 39 to operate the second water supplier 37, and heats the heater 40 with a predetermined output to detect the temperature detected by the temperature sensor 24. The amount of change in the water temperature of the second tank in a predetermined period is determined. The controller 60 determines that the first on-off valve 36 is normal if the amount of change is equal to or greater than a predetermined threshold value. If there is an abnormality in the first on-off valve 36, the water in the second tank 22 may flow into the reformer 11 even if the first on-off valve 36 is closed. For this reason, the flow rate of water supplied from the first tank 21 to the second tank 22 through the third water path 33 by the overflow decreases. As a result, when there is an abnormality in the first on-off valve 36, the water temperature of the second tank 22 rises more gradually than in the case where the first on-off valve 36 is normal. The controller 60 determines, for example, whether or not the first on-off valve 36 is normal using this phenomenon.

  If the determination result in step S4 is affirmative, the process proceeds to step S5, and the controller 60 closes the first on-off valve 36. Next, in step S6, the controller 60 operates the first water supplier 35 and the second water supplier 37. Thereby, water flows through the first water path 31, the second water path 32, and the third water path 33, and the first water path 31, the second water path 32, and the third water path 33 are prevented from freezing. . Next, the controller 60 proceeds to step S7, heats the heater 40 with the first output, and returns to step S1. Thereby, since the water heated by the heater 40 flows through the first water path 31, the second water path 32, and the third water path 33, the first water path 31, the second water path 32, and Freezing of the third water path 33 is prevented. The controller 60 may omit the process of step S7 when the temperature of the water stored in the first tank 21 is relatively high.

  When the determination result in step S3 is negative, the process proceeds to step S8, and the controller 60 determines whether or not the second water path 32 is normal. The process of step S8 is performed similarly to step S4. If the determination result in step S8 is affirmative, the process proceeds to step S9, and the controller 60 closes the first on-off valve 36. Next, it progresses to step S10 and the controller 60 prohibits the operation | movement of the 1st water supply device 35 while operating the 2nd water supply device 37. FIG. Next, in step S11, the controller 60 causes the heater 40 to generate heat at the second output. Next, in step S12, the controller 60 operates the fan 80 and returns to step S1. Thereby, the internal space of the housing 50 can be appropriately warmed by heat radiation from the first tank 21, and freezing of the first water path 31 can be prevented even when water does not flow through the first water path 31.

  If the determination result in step S4 is negative, the process proceeds to step S13, where the controller 60 activates the first water supplier 35 and prohibits the operation of the second water supplier 37. Next, in step S14, the controller 60 causes the heater 40 to generate heat at the second output. Next, in step S15, the controller 60 operates the fan 80 and returns to step S1. Thereby, the internal space of the housing 50 can be appropriately warmed by heat radiation from the first tank 21, and freezing of the second water path 32 can be prevented even if water does not flow through the second water path 32.

  When the determination result in step S8 is negative, the process proceeds to step S16, and the controller 60 causes the heater 40 to generate heat with the second output. Next, in step S17, the controller 60 operates the fan 80 and returns to step S1. In this case, the controller 60 causes the heater 40 to generate heat with the second output without operating the first water supplier 35 and the second water supplier 37. As a result, the internal space of the housing 50 can be properly warmed up by the heat radiation from the first tank 21, and the first water path 31, the second water path 31 can be obtained even if the water does not flow through the first water path 31 and the second water path 32. Freezing of the water path 32 and the third water path 33 can be prevented.

  As shown in FIG. 2 and FIG. 3, if the determination result in step S2 is negative, the process proceeds to step S20, and the controller 60 operates the second water supply device 37 in the second mode. As a result, the water flows backward in the second water passage 32 toward the second tank 22, and the water in the second water passage 32 is discharged. Thereby, even if the heater 40 has an abnormality, freezing of the second water passage 32 can be prevented. When the process of step S20 is completed, the freeze prevention process ends.

  If the determination result in step S1 is negative, the process proceeds to step S18, and the controller 60 executes a predetermined stop process. For example, in step S18, the controller 60 stops the first water supply unit 35, the second water supply unit 37, or the fan 80 when they are operating, and when the heater 40 is generating heat. Turns the heater 40 off. When the process of step S18 is completed, the freeze prevention process ends. The controller 60 skips step S18, for example, when the first water supplier 35, the second water supplier 37, and the fan 80 are not operating and the heater 40 is off. The controller 60 may return to step S1 after the process of step S18 is completed. Furthermore, when the determination result in step S1 is negative, the controller 60 may repeat step S1 until the determination result in step S1 becomes affirmative.

  The fuel cell system 1a can be changed from various viewpoints. For example, the fuel cell system 1a may be modified as the fuel cell system 1b shown in FIG. The fuel cell system 1b is configured in the same manner as the fuel cell system 1a unless otherwise described. The components of the fuel cell system 1b that are the same as or correspond to the components of the fuel cell system 1a are given the same reference numerals, and detailed descriptions thereof will be omitted. The description of the fuel cell system 1a also applies to the fuel cell system 1b, as long as there is no technical contradiction.

  As shown in FIG. 4, the fuel cell system 1 b further includes, for example, a bypass path 32 b and a second on-off valve 38. The bypass path 32 b bypasses the second water supply unit 37 in the second water path 32. The second on-off valve 38 is disposed in the bypass path 32b. The second on-off valve 38 is, for example, an electromagnetic valve. The controller 60 closes the second on-off valve 38 when the fuel cell 10 is generating power (in other words, the above-described start period, power generation period, and stop period). On the other hand, it is assumed that the controller 60 determines that at least one of the first water path 31, the second water path 32, and the third water path 33 may be frozen and that the heater 40 is abnormal. In this case, the controller 60 opens the second on-off valve 38 to discharge water from the second water path 32. Most of the second water path 32 is above the second tank 22. For this reason, when the second on-off valve 38 is opened, the water in the second water path 32 flows backward toward the second tank 22, and the water is discharged from the second water path 32. Thereby, even if the second water supply device 37 can be operated only in the first mode, or even when the second water supply device 37 has an abnormality, the second on-off valve 38 is opened, so that the second water path 32 can be prevented from freezing. For example, as shown in FIGS. 2 and 5, in the fuel cell system 1b, when the determination result in step S2 is negative, the controller 60 proceeds to step S21 and opens the second on-off valve 38. Thereby, water is discharged from the second water path 32. After completion of step S21, the freeze prevention process ends.

Second Embodiment
Next, a fuel cell system 300a according to another embodiment will be described. As shown in FIG. 6, the fuel cell system 300 a includes a fuel cell 310, a reformer 311, a tank 321, a water path 331, a heater 340, a water supplier 335, a housing 350, and a controller 360. And have. The fuel cell 310 generates power by reacting a fuel gas containing hydrogen and an oxidant gas. The reformer 311 generates a fuel gas from the raw material gas and water. The tank 321 stores water to be supplied to the reformer 311. Water supplied to the reformer 311 flows through the water path 331. The heater 340 is disposed inside the tank 321. The water supply unit 335 is disposed in the water path 331 and sends the water stored in the tank 321 to the reformer 311. The housing 350 accommodates the fuel cell 310, the reformer 311, the tank 321, and the water path 331. The controller 360 causes the heater 340 to generate heat at the second output when it is determined that the water path 331 may freeze and there is an abnormality in the water path 331, and the heat of the tank 321 causes the housing 350 to Warm up the interior space. The second output of the heater 340 is higher than the first output of the heater 340 for preventing freezing of the water path 331 when the water path 331 is normal.

  When the controller 360 makes the above determination, the heater 340 generates heat at the second output, so the water stored in the tank 321 is heated to a higher temperature than when the normal antifreeze processing is performed. For this reason, the heat radiation from the tank 321 in which the water heated by the heater 340 is stored extends over a wide range of the internal space of the housing 350. Thereby, even if the water passage 331 has an abnormality and water heated by the heater 340 can not flow to the water passage 331, freezing of the water passage 331 can be advantageously prevented. The second output of the heater 340 is not particularly limited as long as it is higher than the first output. For example, the temperature of the water stored in the tank 321 can be maintained at 70 ° C. or higher. The heater 340 is, for example, a resistance heating type electric heater. In addition, the 1st output of the heater 340 is defined so that the temperature of the water stored by the tank 321 can be maintained at 30-50 degreeC, for example.

  As shown in FIG. 5, the fuel cell system 300a further includes, for example, a temperature sensor 365. The temperature sensor 365 detects, for example, the temperature of air inside the housing 350. The temperature sensor 365 is disposed, for example, near the bottom of the housing 350. The temperature sensor 365 may detect the temperature of the air outside the housing 350 or the temperature of the water in the water path 331. For example, when the temperature sensor 365 detects that the temperature is lower than or equal to the first temperature T1, the controller 360 determines that the water path 331 may be frozen. The first temperature T1 is, for example, 0 ° C. The temperature sensor 365 is, for example, a temperature sensor using a thermistor or a temperature sensor using a thermocouple.

  For example, the controller 360 prohibits the operation of the water supply device 335 when it is determined that the water channel 331 may freeze and the water channel 331 is abnormal.

  The controller 360 determines, for example, an abnormality in the water supplier 335 as an abnormality in the water path 331. For example, the controller 360 acquires information indicating the operating state of the water supply unit 335 and determines whether or not the water supply unit 335 is abnormal.

  The water supply 335 is, for example, one of the positive displacement pumps described above. The water supplier 335 is operable, for example, by switching between the first mode and the second mode. The first mode is a mode in which water is supplied from the tank 321 toward the reformer 311. The second mode is a mode in which water is reversely flowed toward the tank 321 in the water path 331. In this case, the water supplier 335 includes, for example, a pump mechanism operated by a motor capable of rotating in the forward and reverse directions. For example, it is assumed that the controller 360 determines that the water path 331 may be frozen and the heater 340 is abnormal. In this case, the controller 360 operates the water supplier 335 in the second mode to drain water from the water path 331. When the water supplier 335 is operable by switching between the first mode and the second mode, the water supplier 335 operates in the first mode unless otherwise described. For example, the controller 360 determines that the heater 340 is abnormal when acquiring information indicating that the value of the current flowing through the heater 340 is abnormal. After sending the control signal to heat the heater 340, the controller 360 may determine whether the heater 340 is normal based on the temperature rise of the water temperature of the tank 321 in a predetermined period.

  As shown in FIG. 1, the fuel cell system 300a further includes a fan 380, for example. For example, the controller 360 operates the fan 380 when the heater 340 generates heat with the second output. In this case, the heat dissipated from the tank 321 is carried by the flow of air generated by the fan 380, and a wide range of the internal space of the housing 350 is efficiently warmed.

The reformer 311 generates hydrogen by a reforming reaction such as a steam reforming reaction (CH ₄ + H ₂ O → CO + 3H ₂ ). The reformer 311 contains a catalyst for causing the reforming reaction to proceed. For example, a hydrocarbon gas such as city gas or LP gas (liquefied petroleum gas) is supplied to the reformer 311 as a raw material gas. A fuel gas containing hydrogen generated by the reformer 311 is supplied to the fuel cell 310.

  The fuel cell system 300a further includes a fuel gas supply path 312, an oxidant gas supply path 316, an anode off gas path 314, a cathode off gas path 317, a flue gas path 318, and a condensed water path 319. The fuel gas supply path 312 is a flow path for supplying the fuel gas from the reformer 311 to the fuel cell 310. The fuel gas supply path 312 connects the reformer 311 and the anode gas inlet of the fuel cell 310. The oxidant gas supply path 316 is a flow path for supplying air as an oxidant gas to the cathode of the fuel cell 310. An air supply unit 315 is provided in the oxidant gas supply path 316. The air supplier 315 is a device for supplying air to the fuel cell 310. The air supply device 315 is, for example, a fan or a blower. In the oxidant gas supply path 316, other devices such as a humidifier and a valve may be disposed. The anode off gas path 314 is a flow path for discharging unreacted fuel gas and unreacted raw material gas from the anode of the fuel cell 310. The unreacted fuel gas and the unreacted source gas are supplied to the combustor 313 through the anode off gas passage 314. The cathode off gas path 317 is a flow path for discharging the unreacted oxidant gas from the cathode of the fuel cell 310. Unreacted oxidant gas is supplied to the combustor 313 through the cathode off-gas path 317. In the combustor 313, unreacted fuel gas and unreacted raw material gas are combusted, the reformer 311 is heated, and combustion exhaust gas is generated. The combustion of the unreacted fuel gas and the unreacted source gas in the combustor 313 supplies the heat necessary for the reforming reaction. The combustion exhaust gas passage 318 is a flow path for discharging the combustion exhaust gas to the outside of the housing 350. The condensed water path 319 branches from the combustion exhaust gas path 318 and extends to the tank 321. The condensed water path 319 is a flow path for guiding condensed water generated by condensation of water vapor contained in the combustion exhaust gas to the tank 321.

  The fuel cell system 300a further includes, for example, a heat recovery path 370 and a heat exchanger 375. The heat exchanger 375 is disposed in the flue gas passage 318. The heat exchanger 375 is, for example, a heat exchanger such as a double-pipe heat exchanger or a plate heat exchanger.

  The heat recovery path 370 is a flow path for recovering the heat of the combustion exhaust gas. The heat recovery path 370 includes a feed path 371 and a return path 372. The feed path 371 and the return path 372 are connected to the heat exchanger 375, respectively. The feed path 371 constitutes an upstream portion of the heat recovery path 370. The return path 72 constitutes the downstream portion of the heat recovery path 370. The return path 372 is a flow path for guiding water heated in the heat exchanger 375 to a hot water storage tank (not shown). The feed path 371 is a flow path for guiding water to be heated in the heat exchanger 375 to the heat exchanger 375. The heat exchanger 375 is configured to exchange heat between water flowing through the heat recovery path 370 and combustion exhaust gas flowing through the combustion exhaust gas path 318. Thus, the water vapor contained in the combustion exhaust gas is condensed to generate condensed water. The condensed water passage 319 branches from the flue gas passage 318 at a branch point located downstream of the heat exchanger 375 in the flue gas passage 318. The condensed water is led to the tank 321 through the condensed water path 319.

  For example, a water supply unit 377 is disposed in the heat recovery path 370. The water supply unit 377 is disposed in the feed path 371, for example. The water supply unit 377 may be disposed in the return path 372. The water supply 377 is, for example, one of the positive displacement pumps described above.

  For example, a temperature sensor 322 is provided in the tank 321. The temperature sensor 322 is disposed inside the tank 321, and detects the temperature of the water stored in the tank 321. The temperature sensor 322 is, for example, a temperature sensor using a thermistor or a temperature sensor using a thermocouple. Excess water overflows from the tank 321 and is discharged to the outside of the housing 350, for example.

  The fuel cell system 300a includes a control panel 363, for example. The control panel 363 receives input of operating conditions of the fuel cell system 300a and displays the operating state of the fuel cell system 300a.

  The controller 360 is typically a digital computer in which a program for operating the fuel cell system 300a is executably stored. The controller 360 acquires information indicating the detection results of the temperature sensor 365 and the temperature sensor 322 and information indicating the operating condition input to the control panel 363. The controller 360 further acquires information indicating the detection result of another detection device (not shown) such as another temperature sensor, a flow meter, and a gas sensor, for example. In addition, the controller 360 obtains, for example, information indicating the operating states of the water supplier 335, the water supplier 377, and the fan 380, and information indicating the current value in the heater 340. Based on these pieces of information, the controller 360 controls objects to be controlled such as the water supplier 335, the water supplier 377, the heater 340, and the fan 380. Further, the controller 360 causes the control panel 363 to display information indicating the operating state of the fuel cell system 300a.

  In the fuel cell system 300a, antifreeze processing is performed as needed. An example of the antifreeze processing will be described with reference to FIGS. 7 and 8. As shown in FIG. 7, in step S301, the controller 360 acquires information indicating the detected temperature Ta of the temperature sensor 365, and determines whether Ta is equal to or less than the first temperature T1. If the determination result in step S301 is affirmative, the process proceeds to step S302, where the controller 360 determines whether the heater 340 is normal.

  If the determination result in step S302 is affirmative, the process proceeds to step S303, and the controller 360 determines whether the water path 331 is normal. For example, if the water supplier 335 is normal, the controller 360 determines that the water path 331 is normal.

  When the determination result in step S303 is affirmative, the process proceeds to step S304, and the controller 360 operates the water supply unit 335. As a result, water flows through the water passage 331, and freezing of the water passage 331 is prevented. Next, the controller 360 proceeds to step S305, causes the heater 340 to generate heat with the first output, and returns to step S301. Thereby, since the water heated by the heater 340 flows through the water path 331, the water path 331 is more reliably prevented from freezing. Note that the controller 360 may omit the process of step S305 when the temperature of the water stored in the tank 321 is relatively high.

  If the determination result in step S303 is negative, the process proceeds to step S306, and the controller 360 causes the heater 340 to generate heat with the second output. Next, in step S307, the controller 360 operates the fan 380 and returns to step S301. As a result, the internal space of the housing 350 can be properly warmed up by the heat released from the tank 321, and freezing of the water passage 331 can be prevented even if the water does not flow through the water passage 331.

  As shown in FIGS. 7 and 8, when the determination result in step S302 is negative, the process proceeds to step S310, and the controller 360 operates the water supply unit 335 in the second mode. Thereby, water flows backward toward the tank 321 in the water path 331, and the water in the water path 331 is discharged. Thereby, even if the heater 340 has an abnormality, freezing of the water path 331 can be prevented. When the process of step S310 is completed, the freeze prevention process ends.

  When the determination result in step S301 is negative, the process proceeds to step S308, and the controller 360 executes a predetermined stop process. For example, in step S308, the controller 360 stops the water supplier 335 or the fan 380 if they are in operation, and turns off the heater 340 if the heater 340 is generating heat. When the process of step S308 is completed, the freeze prevention process ends. For example, when the water supplier 335 or the fan 380 is not operating and the heater 340 is off, the controller 360 skips step S308. The controller 360 may return to step S301 after the process of step S308 is completed. Furthermore, when the determination result in step S301 is negative, the controller 360 may repeat step S301 until the determination result in step S301 becomes affirmative.

  The fuel cell system 300a can be changed from various viewpoints. For example, the fuel cell system 300b may be modified like a fuel cell system 300b shown in FIG. The fuel cell system 300b is configured in the same manner as the fuel cell system 300a, unless otherwise described. Components of the fuel cell system 300b that are the same as or correspond to components of the fuel cell system 300a are assigned the same reference numerals, and detailed descriptions thereof are omitted. The description of the fuel cell system 300a also applies to the fuel cell system 300b as long as there is no technical contradiction.

  As shown in FIG. 9, the fuel cell system 300 b further includes a bypass path 332 and an on-off valve 338. The bypass path 332 bypasses the water supplier 335 in the water path 331. The on-off valve 338 is disposed in the bypass path 332. The on-off valve 338 is, for example, an electromagnetic valve. The controller 360 closes the on-off valve 338 when the fuel cell 310 is generating power. On the other hand, it is assumed that the controller 360 determines that the water path 331 may freeze and the heater 340 is abnormal. In this case, the controller 360 opens the on-off valve 338 and discharges water from the water path 331. Most of the water path 331 is above the tank 321. For this reason, when the on-off valve 338 is opened, the water in the water path 331 flows backward toward the tank 321, and the water is discharged from the water path 331. Thereby, even when the water supply unit 335 is operable only in the first mode, or even when the water supply unit 335 has an abnormality, the open / close valve 338 is opened, so that the water path 331 can be prevented from freezing. For example, as shown in FIGS. 7 and 10, in the fuel cell system 300b, when the determination result in step S302 is negative, the controller 360 proceeds to step S311 and opens the on-off valve 338. As a result, water is discharged from the water path 331. After completion of step S311, the freeze prevention process ends.

  The technology of the present disclosure is useful for preventing freezing when there is an abnormality in the water path in the fuel cell system.

DESCRIPTION OF SYMBOLS 1a, 1b Fuel cell system 10 Fuel cell 11 Reformer 21 First tank 22 Second tank 31 First water path 32 Second water path 32b Bypass path 33 Third water path 35 First water supply 36 First on-off valve 37 second water supply device 38 second on-off valve 40 heater 50 housing 60 controller 65 temperature sensor 80 fan BP branch point

Claims (15)

A fuel cell;
A first tank for storing water for recovering heat generated by the fuel cell;
A first water path through which water circulating between the fuel cell and the first tank flows;
A reformer that generates the fuel gas from raw material gas and water;
A second tank for storing water to be supplied to the reformer;
A branch point that connects the second tank, the reformer, and the first tank, and branches off the flow of water supplied to the reformer and the flow of water supplied to the first tank. A second water path,
A first on-off valve disposed between the branch point and the reformer in the second water path;
A third water path for leading water overflowing from the first tank to the second tank;
A heater disposed inside the first tank;
A first water supplier that is disposed in the first water path and circulates water between the fuel cell and the first tank;
A second water supplier that is disposed in the second water path and sends water stored in the second tank to at least one of the reformer and the first tank;
A housing for housing the fuel cell, the first tank, the first water path, the reformer, the second tank, the second water path, and the third water path;
And a controller,
The controller may cause at least one of the first water path, the second water path, and the third water path to freeze, and at least one of the first water path and the second water path. From the first output of the heater for preventing freezing of the first water path and the second water path when the first water path and the second water path are normal. Heat the heater with a high second output and heat the internal space of the housing by heat radiation from the first tank,
Fuel cell system. A temperature sensor configured to detect a temperature of air inside the casing or outside the casing, or a temperature of water in at least one of the first water path, the second water path, and the third water path; ,
When the controller detects that the temperature sensor is equal to or lower than the first temperature, at least one of the first water path, the second water path, and the third water path may freeze. to decide,
The fuel cell system according to claim 1.   The controller may cause at least one of the first water path, the second water path, and the third water path to freeze, and the first water path is abnormal and the second water path Is determined to be normal, the heater is heated by the second output, and the first water supply device is operated while the second opening / closing valve is closed and the second water supply device is operated. The fuel cell system according to claim 1 or 2, which is prohibited.   The fuel cell system according to any one of claims 1 to 3, wherein the controller determines that an abnormality in the first water supply device is an abnormality in the first water path.   The controller may cause at least one of the first water path, the second water path, and the third water path to freeze, and the second water path is abnormal and the first water path When the operation is determined to be normal, the heater is heated with the second output, and the operation of the second water supply device is prohibited while the first water supply device is operated. The fuel cell system according to any one of the above.   6. The controller according to claim 1, wherein the controller determines that at least one of an abnormality of the second water supply device and an abnormality of the first on-off valve is an abnormality of the second water path. Fuel cell system. The second water supply unit is configured to supply water from the second tank toward at least one of the reformer and the first tank, and to the second tank in the second water path. Switching between the second mode to backflow water
When the controller determines that at least one of the first water path, the second water path, and the third water path is frozen and the heater is abnormal, The fuel cell system according to any one of claims 1 to 6, wherein a water supply device is operated in the second mode to discharge water from the second water path. A bypass path bypassing the second water supply in the second water path;
And a second on-off valve disposed in the bypass path,
The controller closes the second on-off valve when the fuel cell is generating power, and there is a risk that at least one of the first water path, the second water path, and the third water path will freeze, The fuel cell system according to any one of claims 1 to 6, wherein when it is determined that the heater is abnormal, the second on-off valve is opened to discharge water from the second water path. The apparatus further comprises a fan for circulating air inside the housing,
The fuel cell system according to any one of claims 1 to 8, wherein the controller operates the fan when the heater generates heat with the second output. A fuel cell;
A reformer that generates the fuel gas from raw material gas and water;
A tank for storing water to be supplied to the reformer;
A water path through which water supplied to the reformer flows;
A heater disposed inside the tank;
A water supplier, disposed in the water path, for sending the water stored in the tank to the reformer;
A housing for housing the fuel cell, the reformer, the tank, and the water path;
And a controller,
When the controller determines that there is a possibility that the water path is frozen and that the water path is abnormal, the controller controls the heater for preventing the water path from freezing when the water path is normal. The heater is heated with a second output higher than the first output, and the internal space of the housing is warmed by heat radiation from the tank.
Fuel cell system. A temperature sensor for detecting the temperature of air inside the casing or outside the casing or the temperature of water in the water path;
When the controller detects that the temperature sensor is equal to or lower than a first temperature, the controller determines that the water path may freeze.
The fuel cell system according to claim 10.   The fuel cell system according to claim 10, wherein the controller determines that the water supply is abnormal as the water path is abnormal. The water supply device can be operated by switching between a first mode for supplying water from the tank toward the reformer and a second mode for backflowing water toward the tank in the water path,
When the controller determines that the water path may freeze and the heater is abnormal, the controller operates the water supply device in the second mode to discharge water from the water path. The fuel cell system according to any one of claims 10 to 12. A bypass path for bypassing the water supply in the water path;
And a switching valve disposed in the bypass path,
The controller closes the open / close valve when the fuel cell is generating power, the water path may freeze, and opens the open / close valve when it is determined that the heater is abnormal. The fuel cell system according to any one of claims 10 to 12, wherein water is discharged from the channel. The apparatus further comprises a fan for circulating air inside the housing,
The fuel cell system according to any one of claims 10 to 14, wherein the controller activates the fan when the heater generates heat with the second output.

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