WO2012161217A1

WO2012161217A1 - Fuel cell system

Info

Publication number: WO2012161217A1
Application number: PCT/JP2012/063180
Authority: WO
Inventors: 俊幸海野; 翔横山
Original assignee: Ｊｘ日鉱日石エネルギー株式会社
Priority date: 2011-05-23
Filing date: 2012-05-23
Publication date: 2012-11-29
Also published as: JPWO2012161217A1

Abstract

Provided is a fuel cell system comprising a cell stack for generating electricity using hydrogen-containing gas. The fuel cell system has the following: a recovered water tank which recovers and stores water contained in off gas of the cell stack; a water level sensor which senses whether the water level of the recovered water tank is at a predetermined level; drainage piping for draining the water inside the recovered water tank; an electromagnetic valve provided to the drainage piping; and a control unit which opens the electromagnetic valve for only a predetermined period of time if the water level sensor senses that the water level in the recovered water tank is at the predetermined water level.

Description

Fuel cell system

Various aspects and embodiments of the present invention relate to a fuel cell system that generates power using a fuel cell.

Conventionally, a fuel cell system that includes a cell stack that generates a hydrogen-containing gas using a hydrogen-containing fuel and generates power using the hydrogen-containing gas is known (see, for example, Patent Document 1). The system described in Patent Document 1 includes a reformer that generates a hydrogen-containing gas and a recovered water tank that stores water to be supplied to the reformer. In this recovered water tank, an upper limit water level and a lower limit water level are set, and water level sensors are respectively arranged. When the water level sensor detects that the water level in the recovered water tank exceeds the upper limit water level, the supply of water to the recovered water tank is stopped. Such a recovered water tank is generally provided with a pipe for preventing overflow above the upper limit water level. That is, the recovered water tank is opened to the atmosphere through a pipe for preventing overflow.

In addition, as a fuel cell system, the water generated by the power generation of the fuel cell is recovered and stored in a recovered water tank, and the water stored in the recovered water tank is reused for power generation, etc. Are provided with a water self-supporting system that does not require water supply.

JP 2010-238590 A

By the way, the fuel cell system has been rapidly spread in recent years, and it is desired to be able to realize a usage form according to needs. For example, forced air supply / exhaust type that makes the fuel cell system water self-sustained, burns the outside air that is forcibly taken from the outside by a blower together with the off-gas of the fuel cell in a sealed container and forcibly releases the combustion exhaust gas to the outdoors (Forced Flue: FF type) is desired. In addition, a sealed container means the container sealed with respect to external air except the air supply / exhaust flow path.

Here, when the fuel cell system described in Patent Document 1 is a water self-supporting system, water contained in the off-gas generated from the fuel cell is recovered and stored in the recovered water tank. However, in general, since the drainage pipe for preventing overflow is open to the outside of the apparatus, a part of off-gas or combustion exhaust gas is also used for drainage, in addition to the original function of discarding surplus water. There is a risk of leakage from the piping to the outside of the device. That is, when the fuel cell system described in Patent Document 1 is a water self-sustaining system, the airtightness of the recovered water tank communicating with the combustion system is FF type, although it is sufficient if the fuel cell system is natural intake / exhaust. There is not enough for that. In addition, airtight here means airtight with respect to external air except the inflow path | route of recovered water.

In this technical field, there is a demand for a fuel cell system that can maintain water self-sustained while ensuring the airtightness of the recovered water tank and adopt the FF type.

A fuel cell system according to one aspect of the present invention is a fuel cell system including a cell stack that generates power using a hydrogen-containing gas. The fuel cell system includes a recovered water tank, a water level sensor, a drain pipe, a valve, and a control unit. The recovered water tank recovers and stores water contained in the cell stack off-gas. The water level sensor detects whether or not the water level of the recovered water tank is a predetermined water level. The drainage pipe is a pipe for draining the water in the recovered water tank. The valve is provided in the drain pipe. When the water level sensor detects that the water level of the recovered water tank is a predetermined water level, the control unit opens the valve only for a predetermined period.

According to the fuel cell system according to one aspect of the present invention, the water contained in the cell stack off-gas is recovered, stored in the recovered water tank, and reused. Therefore, it is possible to generate power without supplying water. Further, when the water level of the recovered water tank is a predetermined water level, the valve of the drain pipe provided in the recovered water tank is opened only for a predetermined period by the control unit. Thus, since the water in the recovered water tank can be discharged before the overflow occurs, there is no need to provide an overflow pipe that is always open to the atmosphere. Accordingly, the recovered water tank can be drained while ensuring airtightness.

In one embodiment, a heat exchanger that recovers water contained in the off gas may be provided, and the recovered water tank may store water recovered by the heat exchanger. In one embodiment, a combustion unit that combusts the off-gas and a heat exchanger that recovers water contained in combustion exhaust gas of the combustion unit are provided, and the recovered water tank stores water recovered by the heat exchanger May be. In one embodiment, a hydrogen generation unit that generates a hydrogen-containing gas using a hydrogen-containing fuel may be provided, and the recovered water tank may store water in order to supply water to the hydrogen generation unit.

In one embodiment, the control unit counts the number of opening control instructions for the valve, and determines that an abnormality has occurred when the number of opening control instructions is a predetermined value or more continuously for a predetermined period. Also good. By comprising in this way, abnormality of a water level sensor or a valve can be detected from the contents of control.

In one embodiment, the water level sensor outputs a signal when the water level of the recovered water tank is not a predetermined water level, and stops the signal when the water level of the recovered water tank is a predetermined water level or Connection may be blocked. With this configuration, it can be determined that an abnormality has occurred even when the water level sensor has a disconnection failure.

A pressure sensor for measuring a pressure of a fluid in a flow path from the cell stack to the recovered water tank, and the control unit includes the valve when the pressure detected by the pressure sensor is equal to or greater than a predetermined value. May be closed. With this configuration, even when the pressure of the fluid in the flow path from the cell stack to the reforming water tank suddenly increases, off-gas or combustion exhaust gas is released from the reforming water tank to the atmosphere. This can be surely prevented.

According to the present invention, water can be drained while ensuring the airtightness of the recovered water tank.

It is a block diagram which shows the structure of the fuel cell system which concerns on embodiment. It is a schematic diagram explaining the water self-supporting mechanism of the fuel cell system of FIG. It is a schematic diagram of the heat exchanger shown in FIG. It is a flowchart explaining operation | movement of the fuel cell system which concerns on embodiment. It is a schematic diagram explaining operation | movement of the fuel cell system which concerns on embodiment. It is a flowchart explaining operation | movement of the fuel cell system which concerns on embodiment. It is a block diagram which shows the structure of the fuel cell system which concerns on a modification. It is a block diagram which shows the structure of the fuel cell system which concerns on a modification.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted.

First, the basic configuration of the fuel cell will be outlined. FIG. 1 is a block diagram showing the configuration of the fuel cell system according to the present embodiment. As shown in FIG. 1, the fuel cell system 1 includes a desulfurization unit 2, a water vaporization unit 3, a hydrogen generation unit 4, a cell stack 5, an off-gas combustion unit 6, a hydrogen-containing fuel supply unit 7, The water supply part 8, the oxidizing agent supply part 9, the power conditioner 10, and the control part 11 are provided. The fuel cell system 1 generates power in the cell stack 5 using a hydrogen-containing fuel and an oxidant. The type of the cell stack 5 in the fuel cell system 1 is not particularly limited, and examples thereof include a polymer electrolyte fuel cell (PEFC), a solid oxide fuel cell (SOFC), and phosphoric acid. A fuel cell (PAFC: Phosphoric Acid Fuel Cell), a molten carbonate fuel cell (MCFC: Molten Carbonate Fuel Cell), and other types can be employed. 1 may be appropriately omitted depending on the type of cell stack 5, the type of hydrogen-containing fuel, the reforming method, and the like. Further, the fuel can be used other than the hydrogen-containing fuel that needs to be reformed, and hydrogen gas obtained by dehydrogenation of pure hydrogen or organic hydride may be used.

As the hydrogen-containing fuel, for example, a hydrocarbon fuel is used. As the hydrocarbon fuel, a compound containing carbon and hydrogen in the molecule (may contain other elements such as oxygen) or a mixture thereof is used. Examples of hydrocarbon fuels include hydrocarbons, alcohols, ethers, and biofuels. These hydrocarbon fuels are derived from conventional fossil fuels such as petroleum and coal, and synthetic systems such as synthesis gas. Those derived from fuel and those derived from biomass can be used as appropriate. Specific examples of hydrocarbons include methane, ethane, propane, butane, natural gas, LPG (liquefied petroleum gas), city gas, town gas, gasoline, naphtha, kerosene, and light oil. Examples of alcohols include methanol and ethanol. Examples of ethers include dimethyl ether. Examples of biofuels include biogas, bioethanol, biodiesel, and biojet.

As the oxidizing agent, for example, air, pure oxygen gas (which may contain impurities that are difficult to remove by a normal removal method), or oxygen-enriched air is used.

The desulfurization unit 2 desulfurizes the hydrogen-containing fuel supplied to the hydrogen generation unit 4. The desulfurization part 2 has a desulfurization catalyst for removing sulfur compounds contained in the hydrogen-containing fuel. As the desulfurization method of the desulfurization unit 2, for example, an adsorptive desulfurization method that adsorbs and removes sulfur compounds and a hydrodesulfurization method that removes sulfur compounds by reacting with hydrogen are employed. The desulfurization unit 2 supplies the desulfurized hydrogen-containing fuel to the hydrogen generation unit 4.

The water vaporization unit 3 generates water vapor supplied to the hydrogen generation unit 4 by heating and vaporizing water. For the heating of the water in the water vaporization unit 3, for example, heat generated in the fuel cell system 1 such as recovering the heat of the hydrogen generation unit 4, the heat of the off-gas combustion unit 6, or the heat of the exhaust gas may be used. Moreover, you may heat water using other heat sources, such as a heater and a burner separately. In FIG. 1, only heat supplied from the off-gas combustion unit 6 to the hydrogen generation unit 4 is described as an example, but the present invention is not limited to this. The water vaporization unit 3 supplies the generated water vapor to the hydrogen generation unit 4.

The hydrogen generation unit 4 generates a hydrogen rich gas (hydrogen-containing gas) using the hydrogen-containing fuel from the desulfurization unit 2. The hydrogen generator 4 has a reformer that reforms the hydrogen-containing fuel with a reforming catalyst. The reforming method in the hydrogen generating unit 4 is not particularly limited, and for example, steam reforming, partial oxidation reforming, autothermal reforming, and other reforming methods can be employed. The hydrogen generator 4 may have a configuration for adjusting the properties in addition to the reformer reformed by the reforming catalyst depending on the properties of the hydrogen rich gas required for the cell stack 5. For example, when the type of the cell stack 5 is a polymer electrolyte fuel cell (PEFC) or a phosphoric acid fuel cell (PAFC), the hydrogen generation unit 4 is configured to remove carbon monoxide in the hydrogen-rich gas. (For example, a shift reaction part and a selective oxidation reaction part). The hydrogen generation unit 4 supplies a hydrogen rich gas to the anode 12 of the cell stack 5.

The cell stack 5 generates power using the hydrogen rich gas from the hydrogen generation unit 4 and the oxidant from the oxidant supply unit 9. The cell stack 5 includes an anode 12 to which a hydrogen-rich gas is supplied, a cathode 13 to which an oxidant is supplied, and an electrolyte 14 disposed between the anode 12 and the cathode 13. The cell stack 5 supplies power to the outside via the power conditioner 10. The cell stack 5 supplies the hydrogen rich gas and the oxidant, which have not been used for power generation, to the off gas combustion unit 6 as off gas. Note that a combustion section (for example, a combustor that heats the reformer) provided in the hydrogen generation section 4 may be shared with the off-gas combustion section 6.

The off gas combustion unit 6 burns off gas supplied from the cell stack 5. The off-gas combustion unit 6 mixes the outside air forcibly taken in by a blower (not shown) and off-gas, burns it in a sealed container, and forcibly releases the combustion exhaust gas to the outside as an exhaust gas (Forced Flue: FF type). In addition, an airtight container means the container sealed with respect to indoors other than the external air which supplies and exhausts. The heat generated by the off-gas combustion unit 6 is supplied to the hydrogen generation unit 4 and used for generation of a hydrogen rich gas in the hydrogen generation unit 4.

The hydrogen-containing fuel supply unit 7 supplies hydrogen-containing fuel to the desulfurization unit 2. The water supply unit 8 supplies water to the water vaporization unit 3. The oxidant supply unit 9 supplies an oxidant to the cathode 13 of the cell stack 5. The hydrogen-containing fuel supply unit 7, the water supply unit 8, and the oxidant supply unit 9 are configured by a pump, for example, and are driven based on a control signal from the control unit 11.

The power conditioner 10 adjusts the power from the cell stack 5 according to the external power usage state. For example, the power conditioner 10 performs a process of converting a voltage and a process of converting DC power into AC power.

The control unit 11 performs control processing for the entire fuel cell system 1. The control unit 11 is configured by a device including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input / output interface, for example. The control unit 11 is electrically connected to a hydrogen-containing fuel supply unit 7, a water supply unit 8, an oxidant supply unit 9, a power conditioner 10, and other sensors and auxiliary equipment not shown. The control unit 11 acquires various signals generated in the fuel cell system 1 and outputs a control signal to each device in the fuel cell system 1.

Here, the fuel cell system 1 has a water self-supporting mechanism that collects water generated by the power generation by the cell stack 5 and stores it in a recovered water tank, and reuses the water stored in the recovered water tank for power generation and the like. I have. Water self-supporting means that the fuel cell is maintained in a state where it can continue operation without receiving water from the outside. The off gas generated by the reaction of the cell stack 5 or the combustion exhaust gas discharged from the off gas combustion unit 6 contains moisture. Water is collected from these gases by condensation, treated with deionization, etc. with a water treatment device, and then reused with a reformer (steam reforming), so that fuel cells can be supplied without receiving water from the outside. The mechanism that maintains the state in which the operation can be continued is called a water self-supporting mechanism.

Hereinafter, the water self-supporting mechanism in the FF type fuel cell system 1 will be outlined. FIG. 2 is a block diagram showing the configuration of the fuel cell system according to the present embodiment. In FIG. 2, the water supply part 8 of FIG. 1 is described in detail, and a part not related to the water self-supporting mechanism is partially omitted. As shown in FIG. 2, the fuel cell system 1 includes a heat exchanger 81, a water quality processing unit 82, and a recovered water tank 83. The heat exchanger 81, the water quality treatment unit 82, and the recovered water tank 83 are elements that constitute the water supply unit 8 shown in FIG.

The heat exchanger 81 is connected to the off-gas combustion unit 6. The heat exchanger 81 is supplied with the flue gas from the off-gas combustion unit 6. The heat exchanger 81 cools the inflowing combustion exhaust gas, separates it into exhaust gas and water, and flows out.

The detailed structure of the heat exchanger 81 is shown in FIG. As shown in FIG. 3, the inside of the housing of the heat exchanger 81 is provided with fins 81a, and the inside of the housing is divided into two rooms by the fins 81a. An inlet 81f for cooling water that communicates with the interior of one room is provided on the lower side wall of the housing. A cooling water outlet 81e that communicates with the interior of one room is provided on the upper side wall of the housing. For this reason, the cooling water flows into one room from the inlet portion 81f on the lower side of the casing and flows out from the outlet portion 81e on the upper side of the casing. Furthermore, the upper part of the housing | casing is provided with the inlet part 81b for combustion exhaust gas connected to the inside of the other room. An exhaust gas outlet portion 81c and a water outlet portion 81d communicating with the inside of the other room are respectively provided on the lower side wall and the lower portion of the housing. The combustion exhaust gas flows into the other room from the inlet 81b at the upper part of the casing, and is cooled by the cooling water through the fins 81a on the way to the lower part of the casing. For this reason, the moisture contained in the combustion exhaust gas is condensed into water. The gas separated from the combustion exhaust gas flows out from the outlet portion 81c as exhaust gas and is released to the outdoors (atmosphere) through, for example, piping. On the other hand, the separated water flows out from the outlet portion 81d by gravity.

2, the outlet 81d side of the heat exchanger 81 is connected to the water quality treatment unit 82. The water quality processing unit 82 removes impurities contained in water. The water from which impurities have been removed flows into the recovered water tank 83 and is stored. The recovered water tank 83 is connected to the water vaporization unit 3 via a water pump 92. The water vaporization unit 3 uses the water stored in the recovered water tank 83 to generate water vapor that is supplied to the hydrogen generation unit 4.

Thus, the water generated by the power generation of the cell stack 5 is recovered by the heat exchanger 81, impurities are removed by the water quality processing unit 82, stored in the recovered water tank 83, and reused for power generation. The water self-supporting mechanism appropriately manages the water level of the recovered water tank 83 that increases and decreases every moment according to the operation status of the fuel cell system 1, thereby realizing water self-supporting.

In the recovered water tank 83, a water level sensor 84 is provided. The water level sensor 84 detects whether or not the water level of the recovered water tank 83 is a predetermined water level. The water level sensor 84 is disposed, for example, in the vicinity of the set upper limit water level in order to detect whether or not the water level of the recovered water tank 83 is the limit water level (full water). As the water level sensor 84, for example, various level sensors such as an electrode type, a float switch, an optical sensor, and a photoelectric sensor may be used, or a pressure sensor may be used instead. The recovered water tank 83 is connected to a drain pipe 87 for draining the water in the recovered water tank 83. The drain pipe 87 is connected to, for example, the lower part of the recovered water tank 83 so that the connection port of the drain pipe 87 is always at a position lower than the water level. The drain pipe 87 is provided with an electromagnetic valve 86. The water in the recovered water tank 83 is discharged when the electromagnetic valve 86 is opened, and is not discharged when the electromagnetic valve 86 is closed. Since the recovered water tank 83 communicates with the atmosphere only through the drainage pipe 87, the recovered water tank 83 remains in the atmosphere as long as the drainage pipe 87 is filled with water even when the electromagnetic valve 86 is opened. It is not open.

In the flow path from the cell stack 5 to the recovered water tank 83, a pressure sensor for detecting the fluid pressure is disposed. The first pressure sensor 90 detects the fluid pressure in the flow path connecting the off-gas combustion unit 6 and the heat exchanger 81. The second pressure sensor 91 detects the fluid pressure in the flow path connecting the heat exchanger 81 and the water quality processing unit 82.

The water level sensor 84, the electromagnetic valve 86, and the pressure sensors 90 and 91 described above are electrically or controllably connected to the control unit 11 described above.

Next, the operation of the fuel cell system 1 according to this embodiment will be described. FIG. 4 is a flowchart showing the operation of the fuel cell system 1 according to this embodiment. The control process shown in FIG. 4 is executed by the control unit 11. For example, it is repeatedly executed at a predetermined interval from the power-on timing.

As shown in FIG. 4, first, the control unit 11 determines whether or not an upper limit water level has been detected (S10). The control unit 11 determines whether or not the water level sensor 84 has detected that the water level of the recovered water tank 83 has reached the upper limit water level. As shown in FIG. 5B, the water level sensor 84 outputs a signal when the water level of the recovered water tank 83 is not the upper limit water level, and as shown in FIG. 5A, the recovered water tank When the water level 83 is the upper limit water level, the signal is stopped or the electrical connection is cut off (disconnected). For this reason, the control part 11 determines with having detected the upper limit water level, when a signal is no longer output from the water level sensor 84. FIG. In the process of S10, when it determines with the control part 11 not detecting the upper limit water level, a counter is reset (S22). Details of the counter will be described later. Then, the control process shown in FIG. 4 ends.

On the other hand, when it is determined that the upper limit water level has been detected, the control unit 11 opens the electromagnetic valve 86 for a certain period (S12). As the fixed period, a value that is not too long is adopted so as not to lose water for water independence. Here, as an example, the description will be made with 2 seconds. After a certain period of time, the control unit 11 closes the electromagnetic valve 86 (S14). Then, the control unit 11 increases the counter by one (S16). This counter indicates the number of opening control instructions for opening the solenoid valve 86. Since the opening control of the electromagnetic valve 86 is 2 seconds here, one counter means 2 seconds. That is, this counter can also function as a timer. And the control part 11 determines whether a counter is larger than predetermined value (S18). This predetermined value is determined in advance based on the margin between the detection position of the water level sensor 84 and the capacity of the recovered

water tank

83, and 10 is adopted here. In other words, it can be said that the control unit 11 determines the elapsed time since opening the electromagnetic valve 86 using a counter. For example, if the opening control time is 2 seconds and the determination threshold value of the counter is 10 times, the control unit 11 determines whether the water level has exceeded the upper limit water level for 20 seconds from the timing when the electromagnetic valve 86 is first opened. It can be said that it is judged. If the control unit 11 determines that the counter is not greater than 10, the control unit 11 returns to the process shown in S10. Therefore, if the counter is not greater than 10, the control unit 11 repeatedly executes the processes shown in S12 to S18 as long as the upper limit water level is continuously detected in the process of S10.

On the other hand, if the control unit 11 determines that the counter is greater than 10, it determines that an abnormality has occurred in the fuel cell system 1 and outputs an alarm (S20). Then, the control process shown in FIG. 4 ends.

This completes the control process shown in FIG. By executing the control process shown in FIG. 4, when the water level in the recovered water tank 83 exceeds the upper limit water level, the electromagnetic valve 86 is opened and stored in the recovered water tank 83 until the water level falls below the upper limit water level. Water is released. For this reason, the recovered water tank 83 is controlled so that the water level is lower than the upper limit water level in a state where opening to the atmosphere is avoided. Thus, since the recovered water tank 83 is controlled so as to release water only when the upper limit water level is exceeded, the off-gas that has flowed out of the cell stack 5 or the flue gas that has flowed out of the off-gas combustion unit 6 is converted into the heat exchanger 81. Thus, it is possible to avoid reaching the recovered water tank 83 via the water quality processing unit 82 and being released to the outside air. Therefore, even when the fuel cell system 1 is placed indoors, for example, since the airtightness of the recovered water tank 83 communicating with the combustion system is ensured, no harmful gas is released indoors. Therefore, the fuel cell system 1 can be an FF type. In addition, airtight means that it is airtight with respect to external air except the inflow path | route of recovered water.

Further, if the water level does not decrease even though the electromagnetic valve 86 is controlled to open for a certain period of time, backflow or clogging of the drainage pipe 87 may be considered. For this reason, the number of times of opening control instruction of the electromagnetic valve 86 is counted, and when the number of opening control instructions becomes a predetermined value or more continuously for a predetermined period, it is determined that an abnormality has occurred in the fuel cell system 1. . Since the time for the open control is fixed, the number of times for the open control can be related to the time. That is, when the water level sensor 84 detects that the water level in the recovered water tank 83 continuously exceeds the upper limit water level for a certain period, it is determined that an abnormality has occurred in the fuel cell system 1.

Next, the operation using the output result of the pressure sensor will be described. FIG. 6 is a flowchart for explaining the operation using the output result of the pressure sensor of the fuel cell system 1 according to this embodiment. The control process shown in FIG. 6 is executed by the control unit 11. For example, it is repeatedly executed at a predetermined interval from the power-on timing. Note that when the control processing content of FIG. 6 contradicts the control processing content shown in FIG. 4, the control processing shown in FIG. 6 is given priority.

As shown in FIG. 6, first, the control unit 11 performs pressure measurement (S30). The controller 11 measures the fluid pressure based on the outputs from the pressure sensors 90 and 91. And the control part 11 determines whether the magnitude | size of fluid pressure is more than predetermined value (threshold value) (S32). And the control part 11 complete | finishes the control processing shown in FIG. 6, when the magnitude | size of a fluid pressure is not more than predetermined value. On the other hand, the control part 11 closes the solenoid valve 86, when the magnitude | size of a fluid pressure is more than predetermined value (S34). Then, an alarm is output (S36). Then, the control process shown in FIG. 4 ends. Then, the control process shown in FIG. 6 ends.

This completes the control process shown in FIG. When the control pressure shown in FIG. 6 is executed and the fluid pressure exceeds a predetermined value, the electromagnetic valve 86 is closed. For this reason, due to the increase in fluid pressure, the off-gas flowing out from the cell stack 5 or the combustion exhaust gas flowing out from the off-gas combustion unit 6 reaches the recovered water tank 83 via the heat exchanger 81 and the water quality treatment unit 82, Release to the outside air can be avoided.

As described above, according to the fuel cell system 1 according to the present embodiment, water contained in the off-gas or combustion exhaust gas is recovered, stored in the recovered water tank 83, and reused. Therefore, it is possible to generate power without supplying water. . When the water level of the recovered water tank 83 is a predetermined water level, the electromagnetic valve 86 of the drain pipe 87 provided in the recovered water tank 83 is opened by the control unit 11 only for a predetermined period. Thus, since the water in the recovered water tank 83 can be discharged before the overflow occurs, it is not necessary to provide an overflow pipe that is always open to the atmosphere. Therefore, the recovered water tank 83 can be drained while ensuring airtightness. For this reason, it becomes possible to make the fuel cell system 1 into FF type.

Further, according to the fuel cell system 1 according to the present embodiment, it is possible to detect abnormality of the water level sensor 84 or the electromagnetic valve 86 or clogging of the piping from the control content. Further, according to the fuel cell system 1 according to the present embodiment, even when the water level sensor 84 is broken, it is determined that the upper limit water level has been detected, so it is determined that an abnormality has occurred due to the control shown in FIG. be able to.

Furthermore, according to the fuel cell system 1 according to the present embodiment, even when the pressure of the fluid in the flow path from the cell stack 5 to the recovered water tank 83 suddenly increases, the off gas or the combustion exhaust gas is not recovered from the recovered water. Release from the tank 83 to the atmosphere can be reliably prevented.

Each embodiment described above shows an example of the fuel cell system according to the present invention. The fuel cell system according to the present invention is not limited to the fuel cell system according to the embodiment, and the fuel cell system according to the embodiment may be modified or otherwise changed without changing the gist described in each claim. It may be applied to a thing.

For example, in the above-described embodiment, an example in which the first pressure sensor 90 and the second pressure sensor 91 are provided has been described. Moreover, it is good also as a structure provided only with either one.

In the embodiment described above, an alarm is output in S20 shown in FIG. 4 and S36 shown in FIG. 6, but the present invention is not limited to this. For example, the emergency stop of the fuel cell system 1 may be performed, and other processes may be executed.

In the above-described embodiment, the example in which the heat exchanger 81 shown in FIG. 2 is connected to the off-gas combustion unit 6 has been described. However, the hydrogen generation unit 4 includes the reforming combustion unit, and the off-gas combustion unit 6 and the reformer are modified. It may be connected to either one of the quality combustion parts. In this case, the pressure sensor 90 only needs to measure the pressure in the flow path connected to either the off-gas combustion unit 6 or the reforming combustion unit. Further, the off-gas combustion unit 6 and the reforming combustion unit may be shared by one combustion unit, and the shared combustion unit and the heat exchanger 81 may be connected.

In the above-described embodiment, the water quality processing unit 82 is disposed between the heat exchanger 81 and the recovered water tank 83, and the water recovered by the heat exchanger 81 passes through the water quality processing unit 82 and is recovered. Although the example stored by 83 was demonstrated, it is not restricted to this. For example, the water quality processing unit 82 may be disposed between the recovered water tank 83 and the water vaporization unit 3, and the water stored in the recovered water tank 83 may be supplied to the water vaporization unit 3 through the water quality processing unit 82. . Further, the water quality treatment unit 82 may be disposed between the heat exchanger 81 and the recovered water tank 83 and between the recovered water tank 83 and the water vaporization unit 3.

Further, in the above-described embodiment, the recovery water tank 83 that recovers the moisture contained in the combustion exhaust gas obtained by burning the off gas of the cell stack 5 has been described. However, the embodiment is not limited to this, and is included in the cathode off gas. A recovered water tank that directly recovers moisture may be used. Details will be described below.

FIG. 7 is a block diagram showing a configuration of the fuel system 1 according to the modification. The fuel system 1 shown in FIG. 7 is configured in substantially the same manner as the fuel system 1 shown in FIG. 2, and is used in the gas output destination of the off-gas combustion unit 6 and the heat exchanger 81 as compared with the fuel system 1 shown in FIG. The gas input source and output destination are different. Further, the fuel system 1 shown in FIG. 7 uses a polymer electrolyte fuel cell, and is different from the fuel system 1 shown in FIG. 2 in that an anode humidifier 94 and a cathode humidifier 95 are provided. In the following, in consideration of the ease of understanding the explanation, the overlapping explanation will be omitted, and the explanation will focus on the differences.

The off gas of the anode 12 of the cell stack 5 is supplied to the off gas combustion unit 6 through a flow path connecting the anode 12 and the off gas combustion unit 6. The off gas from the cathode 13 of the cell stack 5 is supplied to the heat exchanger 81 through a flow path connecting the cathode 13 and the heat exchanger 81. The cathode offgas that has passed through the heat exchanger 81 passes through the flow path connecting the cathode 13 and the offgas combustion unit 6 and is supplied to the offgas combustion unit 6.

The off-gas combustion unit 6 inputs the supplied off-gas of the anode 12 and the cathode 13 and the supplied air and burns it, and exhausts the combustion exhaust gas to the outside.

A first pressure sensor 90 is provided in the flow path connecting the cathode 13 and the heat exchanger 81. The first pressure sensor 90 detects the fluid pressure in the flow path in the flow path connecting the cathode 13 and the heat exchanger 81.

The hydrogen rich gas supplied to the anode 12 is humidified by the anode humidifier 94 and supplied to the anode 12. The oxidant (air) supplied to the cathode 13 is humidified by the cathode humidifier 95 and supplied to the cathode 13. The water stored in the recovered water tank 83 can be used as water supplied to applications other than reforming, for example, the anode humidifier 94 and the cathode humidifier 95. In the example shown in FIG. 7, the water stored in the recovered water tank 83 is supplied to the anode humidifier 94 and the cathode humidifier 95 by the water pump 93.

7 can be drained while ensuring the airtightness of the recovered water tank 83.

Furthermore, the fuel cell system 1 shown in FIG. 7 may be modified to the fuel cell system 1 shown in FIG. Compared with the fuel cell system 1 shown in FIG. 7, the fuel cell system 1 shown in FIG. 8 does not include the desulfurization unit 2, the water vaporization unit 3, the hydrogen generation unit 4, and the water pump 92. Instead, a hydrogen cylinder 96 for supplying pure hydrogen is provided. Other configurations are the same as those in FIG. Even the fuel cell system 1 shown in FIG. 8 can be drained while ensuring the airtightness of the recovered water tank 83. When the fuel gas is pure hydrogen, the water stored in the recovered water tank 83 can be used as water supplied to the anode humidifier 94 and the cathode humidifier 95.

DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 4 ... Hydrogen generation part, 5 ... Cell stack, 6 ... Off gas combustion part, 11 ... Control part, 81 ... Heat exchanger, 83 ... Recovery water tank, 84 ... Water level sensor, 86 ... Drain piping, 87 ... Solenoid valve, 90, 91 ... Pressure sensor.

Claims

A fuel cell system including a cell stack that generates power using a hydrogen-containing gas,
A recovered water tank for recovering and storing water contained in the off gas of the cell stack;
A water level sensor for detecting whether or not the water level of the recovered water tank is a predetermined water level;
Drainage piping for draining water in the recovered water tank;
A valve provided in the drainage pipe;
A control unit that opens the valve only for a predetermined period when the water level sensor detects that the water level of the recovered water tank is a predetermined water level;
A fuel cell system.
A heat exchanger for recovering water contained in the off gas;
The fuel cell system according to claim 1, wherein the recovered water tank stores water recovered by the heat exchanger.
A combustion section for burning the off-gas;
A heat exchanger for recovering water contained in the combustion exhaust gas of the combustion section;
The fuel cell system according to claim 1, wherein the recovered water tank stores water recovered by the heat exchanger.
Provided with a hydrogen generation part that generates hydrogen-containing gas using hydrogen-containing fuel,
The fuel cell system according to any one of claims 1 to 3, wherein the recovered water tank stores water in order to supply water to the hydrogen generator.
5. The control unit according to claim 1, wherein the controller counts the number of opening control instructions for the valve and determines that an abnormality has occurred when the number of opening control instructions is a predetermined value or more continuously for a predetermined period. The fuel cell system according to any one of the above.
The water level sensor outputs a signal when the water level of the recovered water tank is not a predetermined water level, and stops the signal or interrupts electrical connection when the water level of the recovered water tank is a predetermined water level. The fuel cell system according to any one of claims 1 to 5.
A pressure sensor that measures the pressure of the fluid in the flow path from the cell stack to the recovered water tank;
The fuel cell system according to any one of claims 1 to 6, wherein the control unit closes the valve when the pressure detected by the pressure sensor is equal to or higher than a predetermined value.