fuel cell device

Abstract

To provide a fuel cell device that can appropriately perform antifreeze operation when the operation is stopped due to abnormality occurrence.SOLUTION: A fuel cell device 100 comprises a first temperature sensor TH7 that detects the outside temperature or a temperature correlated with the outside temperature, second temperature sensors TH5 and TH6 that detect the temperature of water in a water path, and a control device 30 that determines whether the detection results of the first temperature sensor TH7 or the second temperature sensors TH5 and TH6 satisfy antifreeze operation conditions and controls the antifreeze operation. In the case in which the fuel cell power generation is stopped due to an abnormality being detected, when the abnormality is not an abnormality that makes it impossible to perform the antifreeze operation, and the antifreeze operation conditions are satisfied within a predetermined period before the abnormality occurs, the control device 30 executes the antifreeze operation.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a fuel cell device. [Background technology]

[0002] Fuel cell devices are known that generate electricity using a hydrogen-containing fuel gas and an oxygen-containing gas (air) and supply the electricity to the outside. Heat is emitted from the fuel cell as it generates power. Therefore, fuel cell devices are equipped with a heat exchanger that exchanges heat between the exhaust heat from the fuel cell and a heat medium, a circulation flow path through which the heat medium circulates, and a heat storage tank that stores the heat medium. The exhaust heat generated by the power generation of the fuel cell is recovered as a heat medium and stored in the heat storage tank. This heat medium is then used for hot water supply, heating, etc. Water is generally used as the heat medium.

[0003] If the heat transfer medium (water) circulating inside the fuel cell device freezes, it can damage the circulation flow path and cause malfunctions. Therefore, when it is predicted that the water may freeze, an anti-freeze operation is performed to prevent freezing.

[0004] For example, Patent Document 1 discloses a method that includes a temperature detector that detects the temperature of water, and a water circulator and water heater provided in the circulation path, and when the water temperature detected by the temperature detector is below a threshold and it is determined that anti-freeze operation is necessary, the method executes a water circulation operation that drives the water circulator to circulate the water in the circulation path, and a heating operation that operates the heater to heat the water. Also, even when power generation operation is stopped due to some abnormality occurring in the fuel cell device, freezing during operation stoppage can be prevented by determining whether or not anti-freeze operation is necessary based on the temperature detected by the temperature detector. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5179652 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in a fuel cell device having the above configuration, if an abnormality also occurs in the temperature detector during operation stoppage due to an abnormality, there is a risk that the device will not be able to perform anti-freeze operation appropriately.

[0007] The present invention is intended to solve the above-mentioned problems, and aims to provide a fuel cell device that can perform appropriate anti-freeze operation even when operation is stopped due to an abnormality and an abnormality also occurs in the temperature detector. [Means for solving the problem]

[0008] The present invention provides a fuel cell module including a fuel cell that generates electricity using a fuel gas and an oxygen-containing gas; A water path through which water flows; a first temperature sensor that detects an outside air temperature or a temperature correlated with the outside air temperature; a second temperature sensor that detects the temperature of the water in the water path; a control device that determines whether the detection result of the first temperature sensor or the second temperature sensor satisfies a freeze prevention operation condition and controls a freeze prevention operation that prevents freezing in the water path; The control device is a fuel cell device that, when it stops power generation of the fuel cell due to the detection of an abnormality, performs the anti-freeze operation if the abnormality is not an abnormality that makes it impossible to perform the anti-freeze operation and if the anti-freeze operation conditions are met within a specified period before the abnormality occurs. [Effects of the Invention]

[0009] By configuring as described above, it is possible to predict whether or not anti-freeze operation is necessary based on the state within a specified period before the abnormal stop, making it possible to perform anti-freeze operation even if an abnormality occurs in the temperature sensor during the abnormal stop. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a system configuration diagram of a fuel cell device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing an example of anti-freeze operation conditions and anti-freeze release conditions. [Figure 3] 10 is a flowchart for determining whether or not anti-freeze operation is required when an abnormal stop occurs. [Figure 4] FIG. 10 is a diagram comparing the operation of anti-freeze operation under normal conditions and during an abnormal stop. DETAILED DESCRIPTION OF THE INVENTION

[0011] A preferred embodiment of the present invention will be briefly described below, showing the operation of the present invention.

[0012] The fuel cell device of the present invention includes a first temperature sensor that detects the outside air temperature or a temperature correlated with the outside air temperature, a second temperature sensor that detects the temperature of water in a water path, and a control device that determines whether the detection results of the first or second temperature sensor meet the freeze prevention operation conditions and controls the freeze prevention operation to prevent freezing in the water path.When the control device stops power generation of the fuel cell due to the detection of an abnormality, if the abnormality does not make the freeze prevention operation impossible and the freeze prevention operation conditions were met within a predetermined period before the abnormality occurred, the control device executes the freeze prevention operation.In other words, the control device predicts and determines whether the freeze prevention operation is necessary based on the condition within the predetermined period before the abnormal shutdown.As a result, even if an abnormality occurs in the temperature sensor during the operation shutdown and the correct temperature cannot be detected, the freeze prevention operation can be executed if the condition within the predetermined period before the abnormal shutdown was detected as being necessary.

[0013] The predetermined period is a period that includes the time period when the outside temperature is lowest on the day of or the day before the occurrence of the abnormality. By including at least the time period when the outside temperature is lowest on the day of or the day before the occurrence of the abnormality as a target for determination, it is possible to predict with a high degree of probability whether anti-freeze operation is required.

[0014] The system also includes a heater installed in the water path and a third temperature sensor that detects the temperature of the water heated by the heater. When the control device turns on the heater for anti-freeze operation during an abnormal shutdown, it keeps the heater on and only changes the amount of current flowing during anti-freeze operation according to the value detected by the third temperature sensor. One cause of an abnormal shutdown of a fuel cell device is fuel gas leakage, but by not turning the heater on or off even when operation is stopped due to a fuel gas leakage, heating by the heater is prevented from causing a fire. Therefore, the heater can heat water even during an abnormal shutdown, allowing for effective anti-freeze operation.

[0015] The system also includes a heat exchanger that exchanges heat between the exhaust heat of the fuel cell module and water, and a heat storage tank that stores the water heated by the heat exchanger. The heater is installed so that it can heat the water in the heat storage tank. The heater is located underwater, which minimizes the possibility of the fuel gas igniting, allowing for safe anti-freeze operation. [Example]

[0016] An embodiment of the present invention will now be described with reference to the drawings.

[0017] 1 is a system configuration diagram of a fuel cell device according to this embodiment. The fuel cell device 100 includes a fuel cell module 1, and a plurality of accessories for operating the fuel cell module 1, such as a first heat exchanger 2, a heat storage tank 3, a condensed water tank 4, a radiator 5, an air supply device 14, a fuel supply device 15, and a reforming water supply device 16, are housed in a housing 50. It is not necessary to house all of the above-mentioned devices within the housing 50; for example, the first heat exchanger 2 and the heat storage tank 3 may be provided outside the housing 50. It is also possible to omit some of the above-mentioned devices in a fuel cell device.

[0018] The fuel cell module 1 is constructed by housing, inside a box-shaped storage container 10, a fuel cell 11 that generates electricity using fuel gas and oxygen-containing gas, and a reformer 12 that generates fuel gas to be supplied to the fuel cell 11.

[0019] The configuration of the fuel cell 11 is not particularly limited, but may have, for example, a cell stack structure in which a plurality of fuel cell units are arranged. The fuel cell 11 having a cell stack structure is constructed, for example, by fixing the lower end of each fuel cell unit to a manifold using an insulating bonding material such as a glass sealant.

[0020] The reformer 12 steam reforms raw fuel gas such as natural gas or LP gas to generate fuel gas to be supplied to the fuel cell 11. The reformer 12 is connected to a fuel supply device 15 that supplies the raw fuel gas and a reforming water supply device 16 that supplies reforming water, and the raw fuel gas and the reforming water undergo a reforming reaction in the heated reformer 12 to generate fuel gas containing hydrogen.

[0021] The fuel cell 11 is supplied with fuel gas produced in the reformer 12 and air (oxygen-containing gas) introduced by an air supply device 14. As the fuel gas passes through the fuel cell, it reacts with the oxygen-containing gas to generate electricity. The space between the fuel cell 11 and the reformer 12 is the combustion section 13, and the fuel gas and oxygen-containing gas that are not used for power generation join together in the combustion section 13 and are burned. High-temperature exhaust gas is produced by the combustion of this fuel gas, and the reformer 12 is heated by this heat. The exhaust gas produced in this way within the fuel cell module 1 is supplied to the first heat exchanger 2.

[0022] The first heat exchanger 2 is connected to a heat storage tank 3, a heat medium pump P1, and a radiator 5 via piping, forming a first heat medium circulation line HC1. A heat medium is introduced into this first heat medium circulation line HC1, and in the first heat exchanger 2, heat exchange occurs between this heat medium and the exhaust gas, heating the heat medium. Water or the like can be used as the heat medium, and the heat storage tank 3 stores the heat medium whose temperature has been increased by heat exchange. The heat medium stored in the heat storage tank 3 is sent to the radiator 5 to be cooled, and then exchanges heat with the exhaust gas again in the first heat exchanger 2 before returning to the heat storage tank 3. As a result, high-temperature heat medium is stored in the heat storage tank 3 from the top, forming a temperature stratification.

[0023] A supply flow path 25 for replenishing water is connected to the heat storage tank 3. The supply flow path 25 branches off from a supply flow path 26 connected to an external water supply source, and is provided with a water supply valve 25a along the way for opening and closing the flow path. When the fuel cell device 100 is installed or when the water level in the heat storage tank 3 falls below a predetermined level during operation, tap water is supplied to the heat storage tank 3 through the supply flow path 25 by opening the water supply valve 25a.

[0024] The heat storage tank 3 is also provided with a water level detection means 7 for monitoring the amount of water in the heat storage tank 3, and a heater 8 for heating the heat medium. As the water level detection means, a known water level sensor such as a float sensor or a capacitance sensor can be used, which detects the presence of water when the amount of water in the heat storage tank 3 is equal to or greater than a predetermined amount, and detects the absence of water when the amount is below the predetermined amount. In this embodiment, an example is shown in which the water level detection means 7 is provided in one location, but multiple water level detection means 7 may be provided in the vertical direction to detect the water level at multiple locations.

[0025] The heater 8 is disposed in the heat storage tank 3 and heats the water in the heat storage tank 3. For example, when the outside air temperature is low and there is a risk of the water freezing in the fuel cell device 100, electricity can be passed through the heater 8 to raise the water temperature and prevent freezing. Furthermore, when the amount of power generated by the fuel cell 11 exceeds the amount of power consumed by the consumer, electricity can be passed through the heater 8 to consume the excess power.

[0026] In addition, a condensed water tank 4 is connected to the first heat exchanger 2 via a condensed water recovery path 20. When the exhaust gas generated in the fuel cell module 1 is cooled by heat exchange, the water vapor contained in the exhaust gas is separated into water and gas, and the separated water is recovered in the condensed water tank 4 through the condensed water recovery path 20. In the condensed water tank 4, the recovered water is purified by removing impurities through an ion exchanger (not shown) or the like. The purified water is supplied to the reformer 12 by the water supply device 16 and used as reforming water. Meanwhile, the gas from which the water has been removed passes through the exhaust path 21 and is then discharged to the outside of the housing 50.

[0027] The fuel supply device 15 that supplies raw fuel to the reformer 12 is provided with accessories such as a first solenoid valve 150, a pressure sensor 151, a desulfurizer 152, a gas flow meter 153, a fuel pump 154, and a second solenoid valve 155 on a raw fuel flow path 22 that connects to a fuel supply source. The reforming water supply device 16 that supplies reforming water to the reformer 12 is provided with accessories such as a reforming water pump 160 on a reforming water flow path 23 that connects to the condensed water tank 4. The air supply device 14 that supplies oxygen-containing gas to the fuel cell module 1 is provided with accessories such as an air filter 140, an air flow meter 141, and a blower 142 on an oxygen-containing gas flow path 24. Note that the accessories listed here are merely examples, and the configuration may include other accessories.

[0028] The fuel cell device 100 also includes a second heat exchanger 6, a heat pump P2 that circulates the heat medium from the heat storage tank 3, and a second heat medium circulation line HC2 that includes piping connecting these. In the second heat medium circulation line HC2, tap water supplied from the outside via a supply flow path 26 is heated in the second heat exchanger 6 using the high-temperature heat medium stored in the heat storage tank 3. The heated water can be supplied via the supply flow path 26 to a reheating device such as an external water heater.

[0029] Furthermore, the fuel cell device 100 includes a plurality of temperature detection means, such as temperature sensors and thermistors, for measuring the temperatures of various parts inside and outside the housing 50.

[0030] Temperature detection means TH1 to TH6 for measuring the temperature of the heat medium are provided in the flow paths through which the heat medium flows, such as the first heat medium circulation line HC1 and the second heat medium circulation line HC2.

[0031] For example, a tank low thermistor TH1 and a tank high thermistor TH2 are provided as means for detecting the temperature of the heat medium in the heat storage tank 3. The tank low thermistor TH1 detects the temperature of the relatively low-temperature heat medium in the heat storage tank 3 and is provided at the bottom of the heat storage tank 3. The tank high thermistor TH2 detects the temperature of the relatively high-temperature heat medium in the heat storage tank 3 and is provided on the second heat medium circulation line HC2 near the heat storage tank 3. In addition, a heat medium low thermistor TH3 and a heat medium high thermistor TH4 are provided as means for detecting the temperature of the heat medium flowing through the first heat medium circulation line HC1. The heat medium low thermistor TH3 is provided between the heat medium pump P1 and the first heat exchanger 2 and detects the temperature of the heat medium cooled by the radiator 5 and flowing into the first heat exchanger 2. The heat medium high thermistor TH4 is provided between the first heat exchanger 2 and the heat storage tank 3 and detects the temperature of the heat medium after passing through the first heat exchanger 2. Furthermore, the supply flow path 26 is provided with a water inlet thermistor TH5 that detects the temperature of water supplied from the outside, and the delivery flow path 27 is provided with a water outlet thermistor TH6 that detects the temperature of water heated by the second heat exchanger 6.

[0032] Within the fuel cell module 1, there are provided a central temperature sensor TC1 that detects the temperature of the central part of the fuel cell 11, and a combustion section temperature sensor TC2 that detects the temperature of the combustion section 13 where fuel gas and oxygen-containing gas not used for power generation are combusted.

[0033] An outside temperature thermistor TH7 is also provided to detect the ambient temperature of the fuel cell device 100. This outside temperature thermistor TH7 may directly measure the outside temperature, or may measure the temperature of a portion inside the housing 50 that has a correlation with the outside temperature.

[0034] The thermistor is an example of a temperature detection means, and the temperature to be detected and the location of the thermistor are not limited to those in this embodiment.

[0035] Furthermore, the fuel cell device 100 is provided with a control device 30 that controls the operation of various devices, as well as a power supply adjustment unit (power conditioner) 40 that converts the DC power generated by the fuel cell module 1 into AC power and adjusts the amount of the converted electricity supplied to an external load.

[0036] The control device 30 is connected to the auxiliary devices and various sensors that make up the fuel cell system 100, and controls the operation of the fuel cell system 100 based on values ​​detected by the various sensors and instructions from a remote control (not shown).

[0037] The control device 30 causes the fuel cell device 100 to perform anti-freeze operation when it predicts that there is a risk of water freezing inside the fuel cell device 100. Specifically, the control device 30 executes anti-freeze operation when it determines that anti-freeze operation conditions are met. Furthermore, if the control device 30 determines that anti-freeze cancellation conditions are met while the anti-freeze operation is being executed, it stops the anti-freeze operation.

[0038] The anti-freeze operation conditions and anti-freeze cancellation conditions can include the detection value of an outside temperature thermistor TH7 that detects the outside temperature or a temperature correlated with the outside temperature, and the detection values ​​of temperature detection means TH1 to TH6 that measure the temperatures of the water flowing in the water paths (first heat medium circulation line HC1, second heat medium circulation line HC2, supply flow path 26, and delivery flow path 27).The control device 30 compares the temperatures detected by each temperature detection means with a threshold value to determine whether anti-freeze operation is required.

[0039] 2 is a diagram showing an example of the freeze prevention operation conditions and the freeze prevention release conditions. In this embodiment, the freeze prevention operation conditions and the freeze prevention release conditions are determined based on the temperatures detected by the outside air temperature thermistor TH7, the water inlet thermistor TH5, and the hot water outlet thermistor TH6.

[0040] The anti-freeze operation condition is whether the outdoor air temperature thermistor TH7 is equal to or lower than X1°C (e.g., 6°C), the inlet water thermistor TH5 is equal to or lower than Y1°C (e.g., 4°C), or the outlet hot water thermistor TH6 is equal to or lower than Y1°C. When this anti-freeze operation condition is met, the control device 30 determines that anti-freeze operation is necessary and executes anti-freeze operation. In other words, when the outdoor air temperature is equal to or lower than X1°C, anti-freeze operation is executed because the outdoor air temperature is low and there is a high possibility of freezing. Furthermore, when the temperature of the water flowing in from outside or the temperature of the water flowing out to outside is low, there is a possibility of freezing even if the outdoor air temperature is not that low (above X1°C), so anti-freeze operation is executed.

[0041] One anti-freeze release condition is when the outdoor air temperature thermistor TH7 is above X2°C (e.g., 10°C), the inlet water thermistor TH5 is above Y2°C (e.g., 10°C), and the outlet hot water thermistor TH6 is above Y2°C, and when anti-freeze operation has continued for 5 minutes or more (X2>X1, Y2>Y1). When this anti-freeze release condition is met, the control device 30 determines that anti-freeze operation is no longer necessary and stops the anti-freeze operation.

[0042] In the above example, the detection values ​​of the inlet water thermistor TH5 and the outlet hot water thermistor TH6 are used as the water temperature determination conditions, but the temperature detected by other temperature detection means may also be used as the determination condition, or additional temperature conditions may be added. Furthermore, the determination threshold is not limited to the above example, and can be set appropriately taking into account the placement of the temperature detection means, etc.

[0043] During anti-freeze operation, the control device 30 energizes the heater 8 to raise the temperature of the water in the heat storage tank 3, and drives the heat transfer pump P1 and the heat supply pump P2 to circulate the water in the circulation line. The heater 8 may be turned on / off depending on the water temperature; for example, it can be energized when the temperature detected by the heat transfer medium low thermistor TH3 is 30°C or lower, and stopped when it exceeds 40°C. Furthermore, a heater other than the heater 8 may be provided in the path through which the water flows.

[0044] The above is the operation of the anti-freeze operation under normal circumstances. However, the anti-freeze operation can also be performed when power generation operation has stopped due to an abnormality occurring in the fuel cell device 100 (hereinafter, this state will be referred to as abnormal stop or during abnormal stop). By performing the anti-freeze operation during an abnormal stop, it is possible to prevent the water from freezing and damaging the water path before the abnormal stop state is released. However, depending on the cause of the abnormal stop, it may not be possible to perform the anti-freeze operation, and the temperature detection means may not operate normally, so the method for determining whether or not the anti-freeze operation is necessary is different from that under normal circumstances.

[0045] In the event of an abnormal stop, the control device 30 makes a determination using the following procedure. First, the cause of the abnormal stop is not an abnormality that makes it impossible to perform anti-freeze operation. If it is impossible to perform anti-freeze operation in the first place, anti-freeze operation will not be performed. Second, the anti-freeze operation conditions were met within a specified period before the abnormality occurred. When these two conditions are met, anti-freeze operation will be performed.

[0046] The fuel cell system 100 stores data on power generation operation over a certain period of time as an operating history, and can use this stored data to determine whether the freeze prevention operation conditions were met within a specified period of time before the abnormality occurred. In other words, if the freeze prevention operation conditions were met within the specified period of time, it is determined that the freeze prevention operation conditions are likely to be met even during an abnormal shutdown, and freeze prevention operation is performed. This allows freeze prevention operation to be performed even if the temperature detection means is not operating normally during the abnormal shutdown, preventing damage to the system due to freezing.

[0047] 3 is a flowchart for determining whether or not anti-freeze operation is required when the fuel cell device 100 is stopped due to an abnormality. The flowchart starts when an abnormality occurs in the fuel cell device 100 and the power generation operation is stopped.

[0048] First, it is determined whether the cause of the abnormal stop is an abnormality that makes it impossible to perform anti-freeze operation (Step 1). If the answer is NO in Step 1, that is, if anti-freeze operation is impossible to perform, anti-freeze operation is not performed and the determination flow ends. If the answer is YES in Step 1, that is, if anti-freeze operation is possible to perform, proceed to the next step.

[0049] Next, it is determined whether the temperature detected by the outdoor air temperature thermistor TH7 was below X1°C for 15 consecutive seconds during a predetermined period T (e.g., 24 hours) before the abnormality occurred (Step 2). If the answer is YES in Step 2, the anti-freeze operation conditions are met, and the process proceeds to Step 5, where anti-freeze operation is performed. On the other hand, if the answer is NO in Step 2, it is next determined whether the temperature detected by the water inlet thermistor TH5 was below Y1°C for 15 consecutive seconds during the predetermined period T (Step 3). If the answer is YES in Step 3, it is next determined whether the temperature detected by the hot water outlet thermistor TH6 was below Y1°C for 15 consecutive seconds during the predetermined period T (Step 4). If the answer is YES in Step 4, it is then determined whether anti-freeze operation is unnecessary (Step 6), and the determination flow ends without anti-freeze operation being performed.

[0050] In this way, the control device 30 determines whether the freeze prevention operation conditions were met based on the temperatures detected within the predetermined period T before the abnormality occurred, thereby determining the possibility that freeze prevention operation is necessary during the abnormal shutdown. This allows freeze prevention operation to be performed even if the temperature detection means is not operating normally. Furthermore, there are no particular restrictions on the length of time or number of days for the predetermined period T, and it can be set as appropriate.

[0051] However, if the minimum detected temperature around the day of the abnormal shutdown is below the threshold, it is possible to predict a high possibility of freezing during the abnormal shutdown, and therefore it is appropriate to perform anti-freeze operation. Therefore, it is preferable that the predetermined period T includes at least the time period before the abnormal shutdown when the outside temperature is at its lowest. In other words, it is preferable that the predetermined period T be a period that includes the time period when the outside temperature is at its lowest on the day of or the day before the abnormal shutdown.

[0052] The predetermined period T may be specified by time (or number of days) or by time of day. Time can be specified as "xx hours before abnormal shutdown," and time can be specified as "between xx a.m. and xx a.m." Furthermore, the predetermined period T does not need to be constant; for example, the length of the predetermined period T can be changed depending on the outside temperature.

[0053] Incidentally, when power generation operation is stopped due to the detection of an abnormality, the control device 30 determines the need for anti-freeze operation only once. Also, because the temperature detection means may not be operating normally, the control device does not determine the need for anti-freeze operation based on the temperature detected after the abnormal stop. Therefore, even if the anti-freeze cancellation conditions are met while anti-freeze operation is being performed, anti-freeze operation will not be stopped. However, if the abnormal stop state is released or a new abnormality occurs that makes anti-freeze operation impossible while anti-freeze operation is being performed, anti-freeze operation will be stopped. When the abnormal stop state is released, the control device 30 determines the need for anti-freeze operation using the normal judgment procedure.

[0054] In the present embodiment, the temperature conditions for the freeze prevention operation are the same for normal operation and for abnormal stoppage. However, the temperature conditions for normal operation and abnormal stoppage may be different.

[0055] Figure 4 compares the operation of anti-freeze operation under normal conditions and when the system is stopped due to an abnormality. The operation of the heat transfer pump P1 and the heat supply pump P2 is the same under normal conditions and when the system is stopped due to an abnormality. Note that the figure shows a case where the heat transfer pump P1 is duty controlled and the heat supply pump P2 is speed controlled, but the pump drive method is not limited to this.

[0056] Heater 8 is normally turned on / off based on the temperature detected by heat medium low thermistor TH3. In contrast, during an abnormal shutdown, the amount of power supplied is increased or decreased based on the temperature detected by heat medium low thermistor TH3, but the heater is not turned off, and the heater operates differently during normal operation and abnormal shutdown.

[0057] One of the causes of an abnormal shutdown of the fuel cell device 100 is a fuel gas leak, and if a fuel gas leak is suspected, there is a possibility that the fuel gas will ignite when the heater is turned on and off. Therefore, by not turning the heater 8 on and off during an abnormal shutdown, even if operation has been stopped due to a fuel gas leak, heating by the heater 8 is prevented from causing a fire. Therefore, even during an abnormal shutdown, the heater 8 can heat water, thereby effectively preventing freezing.

[0058] Furthermore, by configuring the fuel cell device 100 so that the heater 8 is placed underwater (inside the heat storage tank 3), the heat generating portion of the heater 8 does not come into contact with the fuel gas, further reducing the possibility of the fuel gas igniting. Therefore, anti-freeze operation can be performed more safely during an abnormal shutdown. [Explanation of symbols]

[0059] 1 Fuel Cell Module 2 1st heat exchanger (heat exchanger) 3. Heat storage tank 8 Heater 11 Fuel Cell 30 Control device TH7 Outside temperature thermistor (first temperature sensor) TH5 Water inlet thermistor (secondary temperature sensor) TH6 Water outlet thermistor (second temperature sensor) TH3 Heat Transfer Medium Low Thermistor (Third Temperature Sensor)

Claims

1. a fuel cell module including a fuel cell that generates electricity using a fuel gas and an oxygen-containing gas; A water path through which water flows; a first temperature sensor that detects an outside air temperature or a temperature correlated with the outside air temperature; a second temperature sensor that detects the temperature of the water in the water path; a control device that determines whether the detection result of the first temperature sensor or the second temperature sensor satisfies a freeze prevention operation condition and controls a freeze prevention operation that prevents freezing in the water path; When the control device stops power generation of the fuel cell due to the detection of an abnormality, if the abnormality is not an abnormality that makes it impossible to perform the anti-freeze operation and if the anti-freeze operation conditions were met within a specified period before the abnormality occurred, the fuel cell device will perform the anti-freeze operation.

2. 2. The fuel cell device according to claim 1, wherein the predetermined period of time is a period that includes the time period when the outside air temperature is lowest on the day on which the abnormality occurred or the day before.

3. a heater provided in the water path; a third temperature sensor for detecting the temperature of the water heated by the heater; 3. A fuel cell device according to claim 1, wherein the control device turns on the heater for the anti-freeze operation during an abnormal stop, and while the anti-freeze operation is being performed, the control device changes only the amount of current flowing to the heater while keeping it on, depending on the value detected by the third temperature sensor.

4. a heat exchanger that exchanges heat between the exhaust heat of the fuel cell module and water; a heat storage tank that stores water heated by the heat exchanger, 4. The fuel cell device according to claim 3, wherein the heater is capable of heating the water in the heat storage tank.

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