fuel cell device

Abstract

To provide a fuel cell device capable of bleeding air of a circulation pump while suppressing excessive rise in a temperature of a heat medium.SOLUTION: Air-bleeding control includes first control, and second control started after termination of the first control. In the second control, a control device 30 selectively performs continuous drive of driving a first circulation pump P1 continuously and intermittent drive of driving the first circulation pump while interposing a predetermined OFF period, selectively performs continuous drive of driving a second circulation pump P2 continuously and intermittent drive of driving the second circulation pump while interposing a predetermined OFF period, and does not simultaneously perform the intermittent drive of the first circulation pump P1 and the intermittent drive of the second circulation pump P2. Thereby, since a convective flow of a heat medium in a heat storage tank 3 is not stopped, excessive rise in a temperature of the heat medium around a heater 8 provided in the heat storage tank 3 is prevented, and thereby, boiling of the heat medium can be prevented.SELECTED DRAWING: Figure 4

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 an external source. Such fuel cell devices efficiently utilize energy by recovering heat from exhaust gas generated during power generation, storing it in a heat storage tank, and using it to provide hot water. To this end, the fuel cell device is equipped with a heat exchanger that exchanges heat between the exhaust gas and a heat medium, a heat storage tank that stores the heat medium whose temperature has been increased by heat exchange in the heat exchanger, a circulation path that circulates the heat medium between the heat exchanger and the heat storage tank, and a circulation pump for circulating the heat medium. Water can be used as the heat medium circulated through the circulation path.

[0003] When the temperature of the water in the circulation path rises, the air dissolved in the water appears as air bubbles, causing air pockets in the circulation path. If the air generated in the circulation path enters the circulation pump, air entrapment occurs, reducing the pump's performance. Therefore, air bleeding control is performed to bleed the air from the circulation pump. Generally, air bleeding control involves setting a predetermined OFF period and an operating period to operate the circulation pump intermittently (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-086156 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, a fuel cell device is provided with a heater for heating the heat medium in the circulation path in order to prevent the heat medium from freezing, etc. If air bleeding control is performed while the heater is energized, the convection of the heat medium stops when the heat medium pump is turned off, which may cause the temperature of the heat medium near the heater to rise excessively and boil.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a fuel cell device that can perform air bleeding of a circulation pump while suppressing an excessive temperature rise of a heat medium. [Means for solving the problem]

[0007] 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 first heat exchanger that exchanges heat between exhaust heat from the fuel cell module and a heat medium; a heat storage tank that stores the heat medium; a heater provided in the heat storage tank; a first circulation path through which the heat medium circulates between the heat storage tank and the first heat exchanger; a first circulation pump provided in the first circulation path to circulate the heat medium; a second heat exchanger that exchanges heat between the heat medium stored in the heat storage tank and water supplied from an external source; a second circulation path through which the heat medium circulates between the heat storage tank and the second heat exchanger; a second circulation pump provided in the second circulation path and circulating the heat medium; a control device that controls the power generation of the fuel cell, the control device starts an air bleeding control for driving the first circulation pump and the second circulation pump before the fuel cell starts generating electricity; The air bleeding control includes a first control and a second control that is started after the first control is completed. In the second control, the control device selectively performing continuous driving of the first circulation pump, which is continuously driven, and intermittent driving of the first circulation pump, which is driven with a predetermined OFF period therebetween; selectively performing continuous driving of the second circulation pump, which is continuously driven, and intermittent driving of the second circulation pump, which is driven with a predetermined OFF period therebetween; The first circulation pump and the second circulation pump are alternately driven continuously and intermittently, In addition, the fuel cell device does not simultaneously perform intermittent driving of the first circulation pump and intermittent driving of the second circulation pump. [Effects of the Invention]

[0008] With the above-described configuration, it is possible to perform air bleeding from the circulation pump while suppressing an excessive temperature rise of the heat transfer medium. [Brief explanation of the drawings]

[0009] [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 state transition diagram of the fuel cell device of the present embodiment. [Figure 3] 10 is an example of a time chart illustrating operations of the first circulation pump and the second circulation pump in the second control of the present embodiment. [Figure 4] 10 is a flowchart illustrating operations of the first circulation pump and the second circulation pump in a second control according to the present embodiment. [Figure 5] 10 is a time chart showing the operations of the first circulation pump and the second circulation pump when a request for execution of priority control occurs in the second control of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] A preferred embodiment of the present invention will be briefly described below, showing the operation of the present invention.

[0011] The present invention relates to a fuel cell device including a heat storage tank provided with a heater, and paths for circulating a heat medium stored in the heat storage tank, including a first circulation path provided with a first circulation pump and a second circulation path provided with a second circulation pump, and a control device that starts air bleeding control of the first circulation pump and the second circulation pump before the fuel cell starts generating electricity, the air bleeding control including a first control and a second control that starts after the first control ends, and in the second control, the control device selectively drives the first circulation pump between continuous drive, which continuously operates, and intermittent drive, which operates with a predetermined OFF period, for the second circulation pump, and selectively drives the second circulation pump between continuous drive, which continuously operates, and intermittent drive, which operates with a predetermined OFF period, but does not simultaneously perform intermittent drive of the first circulation pump and the second circulation pump. During the second control, the heat medium always circulates through at least one of the first circulation path and the second circulation path, and convection of the heat medium in the heat storage tank is not stopped, preventing an excessive rise in the temperature of the heat medium around the heater and preventing boiling of the heat medium.

[0012] The control device alternately drives the first circulation pump and the second circulation pump between continuous and intermittent operation, and the time for continuously driving the first circulation pump and the time for continuously driving the second circulation pump are set so that the first circulation pump and the second circulation pump are not intermittently driven at the same time. This makes it possible to reliably control the first circulation pump and the second circulation pump so that they are not intermittently driven at the same time.

[0013] Furthermore, the second control includes a return step that is executed first when transitioning from priority control. When a request for execution of priority control, which has a higher priority than second control, is made for either the first circulation pump or the second circulation pump, the control device interrupts the second control for which priority control was requested, and when priority control is completed, transitions to second control, causing the first circulation pump and the second circulation pump to start from the return step. As a result, even when priority control is requested, the return step is started when transitioning to second control, so that the first circulation pump and the second circulation pump can be controlled so that they are not intermittently driven at the same time.

[0014] Furthermore, the termination condition of the second control includes that the execution time is equal to or longer than a predetermined time, and the control device stops measuring the execution time of the second control while the priority control is being executed. This prevents the execution time of the second control from running short even when a request for priority control is made, and ensures that the air in the heat medium is purged. [Example]

[0015] An embodiment of the present invention will now be described with reference to the drawings.

[0016] 1 is a system configuration diagram of a fuel cell device of 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] The fuel cell 11 is supplied with fuel gas produced in the reformer 12 and air (oxygen-containing gas) introduced by the air supply device 14. As the fuel gas passes through the fuel cell, it reacts with the oxygen-containing gas to generate electricity. The fuel gas and oxygen-containing gas that are not used for power generation join together at the top of the fuel cell 11 and are burned. This combustion of the fuel gas generates high-temperature exhaust gas, which heats the reformer 12. The exhaust gas thus produced within the fuel cell module 1 is supplied to the first heat exchanger 2.

[0021] The first heat exchanger 2 is connected via piping to a heat storage tank 3, a heat medium pump (first circulation pump) P1, and a radiator 5, forming a first circulation path HC1. A heat medium is introduced into this first circulation path HC1, and in the first heat exchanger 2, heat exchange occurs between this heat medium and the exhaust gas described above, heating the heat medium. Water 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 and 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, a high-temperature heat medium is stored in the heat storage tank 3 from the top, forming a temperature stratification.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The fuel cell device 100 also includes a second circulation path HC2 including a second heat exchanger 6, a heat pump (second circulation pump) P2 that circulates the heat medium from the heat storage tank 3, and piping connecting these. In the second circulation path 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 a supply flow path 27 to a reheating device such as an external water heater.

[0028] In the fuel cell device 100, a plurality of temperature detection means TH1 to TH6 such as temperature sensors or thermistors are provided in the flow paths through which the heat medium flows, such as the first circulation path HC1 and the second circulation path HC2, in order to measure the temperature of the heat medium.

[0029] For example, the system includes a tank low thermistor TH1 and a tank high thermistor TH2 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 circulation path HC2 near the heat storage tank 3. The system also includes a heat medium low thermistor TH3 and a heat medium high thermistor TH4 as means for detecting the temperature of the heat medium flowing through the first circulation path HC1. The heat medium low thermistor TH3 is provided between the first circulation 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, a water inlet thermistor TH6 is provided in the supply flow path 26 to detect the temperature of water supplied from the outside, and a hot water outlet thermistor TH6 is provided in the delivery flow path 27 to detect the temperature of water heated by the second heat exchanger 6. These are examples of temperature detection means, and the detected temperature and the location of the detection are not limited to this embodiment. Other temperature detection means may also be provided.

[0030] 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.

[0031] 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).

[0032] 2 is a state transition diagram of the fuel cell device of this embodiment, showing the control procedure of the control device 30 when the fuel cell device 100 generates power.

[0033] When the control device 30 receives an operation start instruction while in a "standby state" in which it waits for an instruction to start operation, it transitions to a "start-up process." The instruction to start operation can be issued, for example, from a remote control installed in the user's home or an operation panel operated by a maintenance worker. In the "start-up process," the heat storage tank 3 and the condensed water tank 4 are filled with water, the first circulation pump P1 and the second circulation pump P2 begin to bleed air, and the reforming water flow path 23 is filled with water. Once the "start-up process" is completed, the control device transitions to an "ignition process." In the "ignition process," fuel gas and air are introduced into the fuel cell module 1 to ignite the fuel gas. Once ignition is confirmed, the control device transitions to a "heating process." In the "heating process," the reformer 12 is heated until the fuel gas and air are combusted and a reforming reaction is possible. Thereafter, the control device transitions to a "power generation process," in which fuel gas, water, and air are supplied to the fuel cell module 1 to generate power in the fuel cell 11. When an instruction to stop power generation is received in the "power generation process," the control device transitions to a "stop process," in which shutdown processing is performed. Once the "stop process" is complete, the system returns to the "standby state" and waits for an instruction to start operation.

[0034] Next, the air bleeding control that is started in the above-mentioned "start-up process" will be described in detail.

[0035] In the "start-up process," the control device 30 first starts filling the heat storage tank 3 with water. Once filling of water has started and the amount of water in the heat storage tank 3 detected by the water level detection means 7 reaches or exceeds a predetermined amount, air removal control is started. Note that if the heat storage tank 3 is already filled with water, air removal control is started without filling the tank with water. In this embodiment, the air removal control includes a first control and a second control that is started after the first control is completed.

[0036] The first control is performed at the start of the air removal control. At the start of the air removal control, there are many air pockets in the circulation paths (first circulation path HC1, second circulation path HC2) and circulation pumps (first circulation pump P1, second circulation pump P2). In the first control, the control device 30 controls the operation of the first circulation pump P1 and the second circulation pump P2 in order to remove these air pockets.

[0037] In the first control, the control device 30 performs intermittent drive of the first circulation pump P1 and the second circulation pump P2, driving them with a predetermined OFF period between them. When duty-controlling the circulation pumps, for example, the pumps are turned ON (driven) for 10 seconds at a duty ratio of 10% and then turned OFF (stopped) for 30 seconds, forming one cycle, and this cycle is repeated multiple times. By performing intermittent drive, the water flow is disturbed, making it easier for air pockets to flow and removing air trapped in the circulation line and circulation pump. Furthermore, the duty ratio in the first control is not constant but can be gradually increased. For example, after repeating two cycles of ON and OFF at a duty ratio of 10%, the duty ratio can be changed to 25% and ON and OFF can be repeated. By gradually increasing the duty ratio in this way, noise generated when driving the circulation pumps can be reduced. Furthermore, the number of repetitions can be increased as the duty ratio is increased. This increases the time the circulation pumps are driven at high output, thereby effectively removing air pockets.

[0038] The circulation pumps may be controlled by their rotation speed. Even when the rotation speed is controlled, they are driven with a predetermined OFF period in between, as in duty control. Furthermore, there are no particular restrictions on the ON and OFF timings of the first circulation pump P1 and the second circulation pump P2. The ON and OFF timings may be the same, or may be staggered.

[0039] The first control ends when the intermittent drive cycle has been performed a predetermined number of times or for a predetermined period of time. When the first control ends, the control device 30 subsequently starts the second control. Furthermore, when the second control starts, the fuel cell device 100 may transition from the "start-up process" to the next "ignition process." By performing the second control together with the next process, the time required to start up the fuel cell device 100 can be shortened.

[0040] The second control is intended to remove air dissolved in the heat medium. As the temperature of the heat medium rises, the air dissolved in the heat medium appears as air bubbles. If these bubbles enter the circulation pump, they will cause air entrapment and reduce the pump's performance. Therefore, by performing the second control, the dissolved air in the heat medium is removed. In the second control, the first circulation pump P1 and the second circulation pump P2 can be selectively driven between continuous drive, which operates continuously, and intermittent drive, which operates with a predetermined OFF period in between. In this case, the control device 30 controls the operation of the first circulation pump P1 and the second circulation pump P2 so that the intermittent drive of the first circulation pump P1 and the intermittent drive of the second circulation pump P2 are not performed simultaneously.

[0041] FIG. 3 is an example of a time chart showing the operation of the first circulation pump and the second circulation pump in the second control of this embodiment. In the figure, continuous drive sections are indicated by shading, and intermittent drive sections are indicated by no shading. The first circulation pump P1 alternates between continuous drive and intermittent drive, as in T1 (continuous) → T2 (intermittent) → T1 (continuous) → T2 (intermittent) → . . . The second circulation pump P2 also alternates between continuous drive and intermittent drive, as in T4 (intermittent) → T3 (continuous) → T4 (intermittent) → T3 (continuous) → . . . However, the intermittent drive sections of the first circulation pump P1 and the second circulation pump P2 do not overlap. In other words, when the first circulation pump P1 is intermittently driven, the second circulation pump P2 is continuously driven, and conversely, when the second circulation pump P2 is intermittently driven, the first circulation pump P1 is continuously driven.

[0042] In the second control, the first circulation pump P1 and the second circulation pump P2 are driven to convect the heat medium in the heat storage tank 3. A heater 8 is provided in the heat storage tank 3, and the heat medium in the heat storage tank 3 is heated by energizing the heater 8. If the heat medium is convected by driving the circulation pumps, the heat from the heater 8 is diffused, allowing the entire heat storage tank 3 to be heated evenly. However, if both circulation pumps are turned off, the convection of the heat medium in the heat storage tank 3 stops. Therefore, if the heater 8 is energized, the temperature of the heat medium around the heater 8 may rise excessively, causing the heat medium to boil. To prevent the heat medium from boiling, the control device 30 controls the operation of the circulation pumps so that the first circulation pump P1 and the second circulation pump P2 are not intermittently driven at the same time. If one circulation pump is continuously driven while the other circulation pump is intermittently driven, a situation in which both are turned off can be easily avoided.

[0043] While the diagram illustrates an example in which T1 to T4 are set to predetermined lengths, the lengths of T1 to T4 may be changed along the way. Furthermore, the lengths T1 and T3 of the continuous drive of the first circulation pump P1 and the second circulation pump P2 may be the same or different. The same applies to the lengths T2 and T4 of the intermittent drive. Furthermore, the first circulation pump P1 starts in continuous drive, while the second circulation pump P2 starts in intermittent drive. Furthermore, once the intermittent drive of the first circulation pump P1 ends, the intermittent drive of the second circulation pump P2 begins. However, the order and timing of starting the intermittent drives are not limited to this. In other words, T1 to T4 can be set as appropriate as long as the intermittent drives of the first circulation pump P1 and the second circulation pump P2 do not overlap.

[0044] Next, a specific example of the operation of the first circulation pump P1 and the second circulation pump P2 will be described.

[0045] 4A and 4B are flowcharts showing the operation of the first circulation pump and the second circulation pump in the second control of this embodiment, where (A) is a flowchart showing the operation of the first circulation pump, and (B) is a flowchart showing the operation of the second circulation pump. The second control is started when the first control ends, and the flow (A) of the first circulation pump P1 and the flow (B) of the second circulation pump P2 start simultaneously.

[0046] In flow (A), the control device 30 performs duty control on the first circulation pump P1. When the second control is started, the first circulation pump P1 is continuously driven at duty ratio X for 5 minutes (S1), and then intermittently driven, with one cycle consisting of 3 seconds off and 10 seconds on at duty ratio X repeated 10 times (S2). When S2 is completed, the process returns to S1.

[0047] In flow (B), the control device 30 controls the rotation speed of the second circulation pump P2. When the second control is started, the second circulation pump P2 is continuously driven at the rotation speed Y for 1 minute 30 seconds (S11), and then intermittently driven, with one cycle consisting of 3 seconds off and 10 seconds on at the rotation speed Y, repeated 10 times (S12). After S12 is completed, the second circulation pump P2 is continuously driven at the rotation speed Y for 5 minutes (S13), and then intermittently driven, with one cycle consisting of 3 seconds off and 10 seconds on at the rotation speed Y, repeated 10 times (S14). After S14 is completed, the process returns to S13.

[0048] If the above-described flow (A) and flow (B) are started simultaneously, the first circulation pump P1 and the second circulation pump P2 will not be intermittently driven simultaneously. Focusing on the duration of continuous drive of the first circulation pump P1 and the second circulation pump P2, the times S1 and S11 are set to different times, and the times S1 and S13 are set to the same time. In other words, the first circulation pump P1 always starts intermittently after five minutes of continuous drive, whereas the second circulation pump P2 starts intermittently for one minute and 30 seconds, and for the same five minutes from the first cycle onward. This allows the timing of the first intermittent drive to be staggered after the start of the second control. Furthermore, the second and subsequent intermittent drives of both the first circulation pump P1 and the second circulation pump P2 are started five minutes after the end of the first intermittent drive (after the end of continuous drive). This prevents the first circulation pump P1 and the second circulation pump P2 from being intermittently driven simultaneously. In this way, by simply setting the time for which the first circulation pump P1 is continuously driven and the time for which the second circulation pump P2 is continuously driven, it is possible to easily and reliably prevent the first circulation pump P1 and the second circulation pump P2 from being intermittently driven at the same time.

[0049] The second control ends when a first predetermined time has elapsed since the start of the second control, or when a second predetermined time (first predetermined time > second predetermined time) has elapsed since the heat medium low thermistor TH3 detected a predetermined temperature. Therefore, when this termination condition is met, flow (A) and flow (B) end. Because dissolved air is more likely to escape as the heat medium temperature increases, when a high heat medium temperature is detected, the second control can be terminated before the first predetermined time has elapsed.

[0050] Next, an operation will be described in the case where an interruption of another control occurs during execution of the second control.

[0051] The air bleed control is a control that drives the first circulation pump P1 and the second circulation pump P2 in a predetermined operation, but the fuel cell device 100 has multiple controls for driving the circulation pumps other than the air bleed control, and each control has a priority order. In other words, if there is a request to execute a control that has a higher priority than the second control (hereinafter referred to as priority control) while the second control is being executed, the second control is interrupted and the priority control is executed. When the priority control is completed, the second control is executed again.

[0052] When an interruption of the priority control occurs only for one of the circulation pumps, the other circulation pump may continue to execute the second control.

[0053] Then, when the priority control ends, the second control starts for both the first circulation pump P1 and the second circulation pump P2; specifically, the first circulation pump P1 starts operation from S1, and the second circulation pump P2 starts operation from S11.

[0054] If a priority control interrupt occurs only for the second circulation pump P2, the first circulation pump P1 continues to execute the second control while the priority control is being executed. Therefore, when the priority control ends and the second circulation pump P2 returns to the second control, there is a risk that the intermittent drive timings will overlap. Therefore, a return step that is executed first when the priority control is switched over is preset in the second control, and when the priority control ends, both the first circulation pump P1 and the second circulation pump P2 start from the return step. In this embodiment, since the start of the second control is the return step, when the priority control ends, the second control starts from the start. This prevents the intermittent drive timings from overlapping when the second control is resumed.

[0055] The return step is not limited to the start of the second control. The return step is a step in which the timings of the intermittent driving of the first circulation pump P1 and the second circulation pump P2 do not overlap when the control is started from that point. Therefore, the return step may be set to satisfy this condition. Furthermore, when transitioning from priority control, a step not included in the normal second control may be added and used as the return step.

[0056] While the priority control is being executed, measurement of the execution time of the second control is stopped, and measurement is started when the second control is returned to.

[0057] 5 is a time chart showing the operation of the first circulation pump and the second circulation pump when a request to execute priority control is issued during the second control of this embodiment. The figure shows the start time of the second control as t0, the interruption of priority control to the second circulation pump P2 at time t1, and the end of priority control at time t2, when the second control resumes. Furthermore, the continuous drive section is shown shaded, and the intermittent drive section is shown without shading, with S representing a step in the flowchart.

[0058] When the second control is started at time t0, the first circulation pump P1 starts continuous driving for 5 minutes in step S1. Meanwhile, the second circulation pump P2 starts intermittent driving in step S12 after being continuously driven for 1 minute 30 seconds in step S11, and when the intermittent driving ends, starts continuous driving for 5 minutes in step S13. While the second circulation pump P2 is continuously driving for 5 minutes, the first circulation pump P1 starts intermittent driving in step S2.

[0059] Next, at time t1, when the second circulation pump P2 is interrupted by priority control, the second circulation pump P2 executes priority control from time t1 to time t2, while the first circulation pump P1 continues to execute second control (continuous operation for 5 minutes).

[0060] Then, when priority control ends at time t2, both the first circulation pump P1 and the second circulation pump P2 resume second control from the start of second control. The first circulation pump P1 returns to S1 and begins continuous operation for five minutes from this point. The second circulation pump P2 returns to S11 and begins continuous operation for one minute and 30 seconds. In this way, when priority control ends, by starting both the first circulation pump and the second circulation pump from the start of second control, overlapping timing of intermittent operation is prevented.

[0061] As described above, in the fuel cell device 100 of this embodiment, in the second control for removing air from the heat medium, the control device 30 controls the first circulation pump P1 and the second circulation pump P2 so that they are not intermittently driven simultaneously. This ensures that the heat medium always circulates through at least one of the first circulation path HC1 and the second circulation path HC2, and does not stop the convection of the heat medium in the heat storage tank 3. Therefore, even when the heater 8 that heats the heat medium is energized, an excessive increase in the temperature of the heat medium around the heater 8 can be prevented, and boiling of the heat medium can be prevented.

[0062] Furthermore, the control device 30 may alternately drive the first circulation pump P1 and the second circulation pump P2 between continuous and intermittent operation, and the time for which the first circulation pump P1 is continuously driven and the time for which the second circulation pump P2 is continuously driven may be set so that the first circulation pump P1 and the second circulation pump P2 are not intermittently driven at the same time. This makes it possible to easily and reliably control the first circulation pump P1 and the second circulation pump P2 so that they are not intermittently driven at the same time.

[0063] Furthermore, the second control can be set with a return step that is executed first when transitioning from priority control. When a request for execution of priority control, which has a higher priority than second control, is made, the control device 30 interrupts the second control of the circulation pump for which priority control was requested. Then, when priority control is completed, transition to second control can be made, and the first circulation pump P1 and the second circulation pump P2 can be started from the return step. This makes it possible to control the first circulation pump P1 and the second circulation pump P2 so that they are not intermittently driven simultaneously when transitioning to second control, even when priority control is requested.

[0064] Furthermore, the termination condition of the second control includes that the execution time is equal to or longer than a predetermined time. The control device may stop measuring the execution time of the second control while executing the priority control. This prevents the execution time of the second control from running short even when a request for priority control is made, and ensures that air is removed from the heat medium. [Explanation of symbols]

[0065] 1 Fuel Cell Module 2 First heat exchanger 3. Heat storage tank 6 Second heat exchanger 8 Heater (heater) 30 Control device HC1 First Circulation Route HC2 Second Circulation Route P1 First Circulation Pump P2 Second Circulation Pump

Claims

1. a fuel cell module including a fuel cell that generates electricity using a fuel gas and an oxygen-containing gas; a first heat exchanger that exchanges heat between exhaust heat from the fuel cell module and a heat medium; a heat storage tank that stores the heat medium; a heater provided in the heat storage tank; a first circulation path through which the heat medium circulates between the heat storage tank and the first heat exchanger; a first circulation pump provided in the first circulation path to circulate the heat medium; a second heat exchanger that exchanges heat between the heat medium stored in the heat storage tank and water supplied from an external source; a second circulation path through which the heat medium circulates between the heat storage tank and the second heat exchanger; a second circulation pump provided in the second circulation path and circulating the heat medium; a control device that controls the power generation of the fuel cell, the control device starts an air bleeding control for driving the first circulation pump and the second circulation pump before the fuel cell starts generating electricity; The air bleeding control includes a first control and a second control that is started after the first control is completed. In the second control, the control device selectively performing continuous driving of the first circulation pump, which is continuously driven, and intermittent driving of the first circulation pump, which is driven with a predetermined OFF period therebetween; selectively performing continuous driving of the second circulation pump, which is continuously driven, and intermittent driving of the second circulation pump, which is driven with a predetermined OFF period therebetween; The first circulation pump and the second circulation pump are alternately driven continuously and intermittently, Furthermore, the fuel cell device does not perform intermittent driving of the first circulation pump and intermittent driving of the second circulation pump at the same time.

2. A fuel cell device as described in claim 1, wherein the time for which the first circulation pump is continuously driven and the time for which the second circulation pump is continuously driven are set so that intermittent driving of the first circulation pump and the second circulation pump is not performed simultaneously.

3. When a request for execution of priority control having a higher priority than the second control is made to either the first circulation pump or the second circulation pump, the second control of the pump for which the request for execution of priority control is made is suspended. The second control includes a return step that is executed first when the priority control is shifted to, 3. The fuel cell device according to claim 2, wherein the control device transitions to the second control when the priority control ends, and starts the first circulation pump and the second circulation pump from the return step.

4. the termination condition of the second control includes that the execution time is equal to or longer than a predetermined time, 4. The fuel cell device according to claim 3, wherein the control device stops measuring the execution time of the second control while the priority control is being executed.

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