JP6983265B2 - Fuel cell system - Google Patents

Description

The present invention relates to a fuel cell system.

The following Patent Document 1 discloses a fuel cell system that reforms a raw material gas with steam to generate a fuel gas containing hydrogen. In this fuel cell system, the water vapor contained in the off-gas discharged from the first fuel cell is stored in the water tank.

Japanese Unexamined Patent Publication No. 2017-69103

In the fuel cell system described in Patent Document 1, it is described that when a predetermined amount or more of water is stored in a water tank, drainage may be performed by, for example, overflow. In this way, in order to drain water from the water tank, it is necessary to provide a drain pipe for drainage.

In view of the above facts, an object of the present invention is to provide a fuel cell system capable of controlling the amount of drain water produced.

The fuel cell system according to claim 1 is a fuel gas obtained by steam reforming a raw material gas using a vaporizer that vaporizes water supplied from a water supply pipe to generate steam and steam generated by the vaporizer. The reforming unit that generates the fuel, the fuel cell that generates power by reacting the fuel gas generated in the reforming unit with the oxidation gas, and the water vapor contained in the off gas discharged from the fuel electrode of the fuel cell. The first water tank in which condensed condensed water is stored and to which the water supply pipe is connected and the first water tank are controlled by controlling the amount of power generated by the fuel cell to adjust the amount of water vapor charged into the first water tank. (1) A control device for maintaining the amount of water in the water tank within a predetermined range is provided.

The fuel cell system according to claim 2 is the fuel cell system according to claim 1. In the fuel cell system according to claim 1, the control device controls the amount of condensed water charged into the first water tank and the condensed water discharged from the first water tank to the water supply pipe. At least one of the water amounts is adjusted to maintain the water amount in the first water tank within a predetermined range.
According to the fuel cell system of claim 2, the control device adjusts at least one of the amount of condensed water charged into the first water tank and the amount of condensed water discharged from the first water tank to the water supply pipe. For example, when the amount of water in the water tank reaches a predetermined upper limit, the amount of condensed water charged into the first water tank is reduced. Alternatively, increase the amount of condensed water discharged from the first water tank to the water supply pipe. As a result, the amount of water in the first water tank can be maintained within a predetermined range, and the amount of drainage from the first water tank can be reduced. The "reforming unit" refers to both the reformer provided separately from the fuel cell and the portion where the reforming reaction is performed in the fuel cell.
The fuel cell system according to claim 3 is the fuel cell system according to claim 1 or 2, wherein the control device reduces the amount of water vapor contained in the off-gas by reducing the amount of power generation of the fuel cell. It is possible to reduce the amount of water vapor charged into the first water tank.
The fuel cell system according to claim 4 is the fuel cell system according to any one of claims 1 to 3 , wherein the control device is included in the off-gas by increasing the amount of power generation of the fuel cell. It is possible to increase the amount of water vapor charged into the first water tank by increasing the amount of water vapor.
The fuel cell system according to claim 5 is the fuel cell system according to any one of claims 1 to 4 , wherein the fuel cell contains the fuel gas and the oxide gas generated in the reforming section. The control device comprises a first fuel cell that reacts to generate power, and a second fuel cell that reacts an unreacted fuel gas contained in the off-gas with an oxidation gas to generate power. The amount of water generated in at least one of the fuel cell and the second fuel cell is controlled to adjust the amount of water vapor charged into the first water tank.
The fuel cell system according to claim 6 is the fuel cell system according to claim 5 , wherein the second fuel cell is arranged on the downstream side of the first water tank.
The fuel cell system according to claim 7. In the fuel cell system according to claim 6, the control device reduces the amount of water vapor contained in the off-gas by reducing the amount of power generated by the first fuel cell, and the first. By reducing the amount of water vapor charged into the water tank and increasing the amount of power generated by the second fuel cell, the reduction in the amount of power generation is suppressed.

The fuel cell system according to claim 8 is a fuel gas obtained by steam reforming a raw material gas using a vaporizer that vaporizes water supplied from a water supply pipe to generate steam and steam generated by the vaporizer. A fuel cell that generates power by reacting the fuel gas generated in the reforming section with an oxidation gas, and condensed water vapor contained in the off-gas discharged from the fuel cell. Included in the first water tank in which water is stored, a combustor that burns the off gas discharged from the fuel cell with the oxide off gas discharged from the air electrode of the fuel cell, and the exhaust gas discharged from the combustor. The amount of water vapor charged into the first water tank and the amount of water vapor charged into the second water tank by controlling the power generation amount of the fuel cell and the second water tank in which the condensed water in which the water vapor is condensed is stored. It is provided with a control device for maintaining the amount of water in the first water tank or the amount of water in the second water tank within a predetermined range by adjusting at least one of them.

The fuel cell system according to claim 9 is the fuel cell system according to claim 8 , wherein the control device has a condensed water amount charged into the first water tank, a condensed water amount discharged from the first water tank, and the like. By adjusting at least one of the amount of condensed water charged into the second water tank and the amount of condensed water discharged from the second water tank, the amount of water in the first water tank or the second water tank is set within a predetermined range. maintain.
According to the fuel cell system of claim 9 , the control device determines the amount of water vapor charged into the first water tank, the amount of condensed water charged into the first water tank, the amount of condensed water discharged from the first water tank, and the second water. At least one of the amount of condensed water charged into the tank, the amount of water vapor charged into the second water tank, and the amount of condensed water discharged from the second water tank is adjusted. For example, when the amount of water in the second water tank reaches a predetermined upper limit, the amount of condensed water charged into the second water tank is reduced. As a result, the amount of water in the first water tank or the second water tank can be maintained within a predetermined range, and the drainage from the first water tank or the second water tank can be reduced.

In one aspect of the fuel cell system, a vaporizer that vaporizes water supplied from a water supply pipe to generate steam, and a vaporizer that steam-reforms the raw material gas using the steam generated by the vaporizer to produce fuel gas. The reforming section to be generated, the fuel cell generated by reacting the fuel gas generated in the reforming section with the oxidation gas to generate power, and the water vapor contained in the off gas discharged from the fuel electrode of the fuel cell are condensed. It is included in the first water tank in which the condensed water is stored, the combustor that burns the off gas discharged from the fuel cell with the oxide off gas discharged from the fuel cell, and the exhaust gas discharged from the combustor. A second water tank in which condensed water in which water vapor is condensed is stored, and in the condensed water and the second water tank installed below the first water tank and the second water tank and stored in the first water tank. The stored condensed water is charged into the aggregation tank to which the water supply pipe is connected, the water supply pipe that supplies the condensed water stored in the aggregation tank to the vaporizer, and the first water tank. Water vapor amount, condensed water amount charged into the first water tank, condensed water amount charged into the second water tank, water vapor amount charged into the second water tank, and discharged from the aggregation tank to the water supply pipe. It is provided with a control device for adjusting at least one of the amount of condensed water to be produced to maintain the amount of water in the aggregation tank within a predetermined range.

According to one aspect of the fuel cell system, the condensed water stored in the first water tank and the condensed water stored in the second water tank are charged into the aggregation tank. Therefore, the amount of water in the first water tank and the second water tank can be maintained within a predetermined range, and drainage from the first water tank and the second water tank to the outside of the system can be eliminated.

Then, the control device determines the amount of condensed water charged into the first water tank, the amount of condensed water charged into the second water tank, the amount of water vapor charged into the second water tank, and the condensation discharged from the aggregation tank to the water supply pipe. Adjust at least one of the amounts of water. The "condensed water" charged into the second water tank is, for example, water (liquid phase) in which water vapor is cooled and condensed on the upstream side of the second water tank. Further, the "water vapor" charged into the second water tank is water (gas layer) that is not condensed and maintains a gaseous state on the upstream side of the second water tank.

For example, when the amount of water in the aggregation tank reaches a predetermined upper limit, as an example, the amount of condensed water charged into the first water tank is reduced. As another example, the amount of condensed water charged into the second water tank is reduced. As yet another example, the amount of water vapor charged into the second water tank is reduced. As yet another example, the amount of condensed water discharged from the aggregation tank to the water supply pipe is increased. By using one or a combination of these, the amount of water in the aggregation tank can be maintained within a predetermined range, and the amount of drainage from the aggregation tank can be reduced.

In one aspect of the fuel cell system, the water level sensor is provided in the aggregation tank, and the control device determines the amount of condensed water charged into the first water tank based on the information from the water level sensor. (2) At least one of the amount of condensed water charged into the water tank, the amount of water vapor charged into the second water tank, and the amount of condensed water discharged from the aggregation tank to the water supply pipe is adjusted.

According to one aspect of the fuel cell system, since the water level sensor is provided in the aggregation tank, the water level in the aggregation tank can be accurately measured. Therefore, it is easy to maintain the amount of water in the aggregation tank within a predetermined range.

In one aspect of the fuel cell system, a partition plate is provided inside the aggregation tank to partition the air chamber in which the off gas is stored and the air chamber in which the exhaust gas is stored.

According to one aspect of the fuel cell system, inside the aggregation tank, an air chamber in which off-gas is stored and an air chamber in which exhaust gas is stored are separated by a partition plate. Therefore, the off gas and the exhaust gas are not mixed. As a result, off-gas containing fuel gas is suppressed from being discharged to the outside of the system.

The fuel cell system according to claim 10 is the fuel cell system according to claim 8 or 9 , wherein the exhaust gas is cooled on the upstream side of the second water tank to condense the water vapor contained in the exhaust gas. A second cooling mechanism is provided, and the control device controls the second cooling mechanism to adjust the amount of condensed water charged into the second water tank.

According to the fuel cell system of claim 10 , the control device controls a second cooling mechanism that cools the exhaust gas on the upstream side of the second water tank and condenses the water vapor. For example, when the amount of water in the aggregation tank reaches a predetermined upper limit, the cooling function is suppressed to reduce the amount of condensed water vapor contained in the exhaust gas. As a result, the amount of condensed water charged into the second water tank and the aggregation tank can be reduced.

Fuel cell system according to claim 11 is the fuel cell system according to any one of claims 8 to claim 10, a bypass valve for discharging the exhaust gas without passing through the second water tank The control device controls the bypass valve to adjust the amount of water vapor charged into the second water tank.

According to the fuel cell system of claim 11 , the control device controls a bypass valve for discharging the exhaust gas without passing through the second water tank. For example, when the amount of water in the aggregation tank reaches a predetermined upper limit, the bypass valve is opened and the exhaust gas containing water vapor is discharged. As a result, the amount of water vapor charged into the second water tank and the aggregation tank is reduced. In this way, the amount of water vapor charged into the second water tank can be adjusted with a simple structure provided with a bypass valve.

The fuel cell system according to claim 12 is the fuel cell system according to any one of claims 8 to 11 , wherein the fuel cell contains the fuel gas and the oxide gas generated in the reforming section. The control device comprises a first fuel cell that reacts to generate power, and a second fuel cell that reacts an unreacted fuel gas contained in the off-gas with an oxidation gas to generate power. The amount of power generated by at least one of the fuel cell and the second fuel cell is controlled to adjust the amount of water vapor charged into the first water tank or the second water tank.

According to the fuel cell system of claim 12 , the control device controls the amount of power generation of at least one of the fuel cell and the subsequent fuel cell. For example, when the amount of water in the first water tank reaches a predetermined upper limit, the amount of power generation in the fuel cell is reduced, and the amount of water vapor generated in the off-gas and off-gas is reduced. As a result, the amount of water vapor charged into the first water tank can be reduced.

The fuel cell system according to claim 13 is the fuel cell system according to claim 12 , wherein the subsequent fuel cell is arranged on the downstream side of the first water tank.

According to the fuel cell system of claim 13 , the control device can maintain the power generation amount of the entire system by reducing the power generation amount of the fuel cell and increasing the power generation amount of the subsequent fuel cell.

The fuel cell system according to claim 14 cools the off-gas in the upstream side of the first water tank or in the first water tank in the fuel cell system according to any one of claims 1 to 13. A first cooling mechanism for condensing the water vapor contained in the off-gas is provided, and the control device controls the first cooling mechanism to adjust the amount of condensed water charged into the first water tank.

According to the fuel cell system of claim 14 , the control device controls a first cooling mechanism that cools the off-gas upstream of the first water tank or in the first water tank to condense water vapor. For example, when the amount of water in the aggregation tank reaches a predetermined upper limit, the cooling function is suppressed to reduce the amount of condensed water vapor contained in the off-gas. As a result, the amount of condensed water charged into the first water tank and the aggregation tank can be reduced.

The fuel cell system according to claim 15 includes, in the fuel cell system according to any one of claims 1 to 14 , a flow rate adjusting mechanism for adjusting an input amount of the raw material gas, and the control device is the control device. The flow rate adjustment mechanism is controlled to adjust the amount of power generation.

According to the fuel cell system of claim 15 , the control device can control the flow rate adjusting mechanism to control the input amount of the raw material gas. For example, when the amount of water in the aggregation tank reaches a predetermined upper limit, the amount of raw material gas input is reduced to reduce the amount of power generation. As a result, the generation of water vapor accompanying the power generation reaction is suppressed, and the amount of water vapor charged into the first water tank and the aggregation tank is reduced.

The fuel cell system according to claim 16 is the fuel cell system according to any one of claims 1 to 15 , wherein the off-gas oxide discharged from the air electrode of the fuel cell is discharged from the fuel cell. A combustor that burns off-gas, an exhaust pipe that discharges the exhaust gas discharged from the combustor to the outside of the system, an exhaust pipe that discharges the exhaust gas discharged from the combustor to the outside of the system, and the first. A water drop supply pipe for supplying the condensed water stored in the water tank to the exhaust pipe is provided, and the control device controls the amount of condensed water supplied to the exhaust pipe and discharges the condensed water from the first water tank. Adjust the amount of condensed water to be produced.

According to the fuel cell system of claim 16 , the control device controls the amount of condensed water supplied to the exhaust pipe. For example, when the amount of water in the first water tank reaches a predetermined upper limit, the amount of condensed water supplied to the exhaust pipe is increased. The condensed water supplied to the exhaust pipe evaporates due to the heat of the exhaust gas and is discharged to the outside of the system as water vapor. As a result, the amount of water vapor discharged from the first water tank to the outside of the system can be increased.

The fuel cell system according to claim 17 is the fuel cell system according to any one of claims 8 to 13 , wherein the exhaust pipe for discharging the exhaust gas discharged from the combustor to the outside of the system and the exhaust pipe are described. A water droplet supply pipe for supplying the condensed water stored in at least one of the first water tank and the second water tank to the exhaust pipe is provided, and the control device measures the amount of condensed water supplied to the exhaust pipe. Controlled to adjust the amount of condensed water discharged from at least one of the first water tank and the second water tank.

According to the fuel cell system of claim 17 , the control device controls the amount of condensed water supplied to the exhaust pipe. For example, when the amount of water in the second water tank reaches a predetermined upper limit, the amount of condensed water supplied to the exhaust pipe is increased. The condensed water supplied to the exhaust pipe evaporates due to the heat of the exhaust gas and is discharged to the outside of the system as water vapor. As a result, the amount of water vapor discharged from at least one of the first water tank and the second water tank to the outside of the system can be increased.

The fuel cell system of one embodiment is stored in at least one of the exhaust pipe for discharging the exhaust gas discharged from the combustor to the outside of the system, the first water tank, the second water tank, and the aggregation tank. A water droplet supply pipe for supplying and supplying the condensed water to the exhaust pipe is provided, and the control device controls the amount of condensed water supplied to the exhaust pipe to control the amount of the condensed water to be supplied to the first water tank and the second water tank. The amount of condensed water discharged from at least one of the water tank and the aggregation tank is adjusted.

According to one aspect of the fuel cell system, the control device controls the amount of condensed water supplied to the exhaust pipe. For example, when the amount of water in the aggregation tank reaches a predetermined upper limit, the amount of condensed water supplied to the exhaust pipe is increased. The condensed water supplied to the exhaust pipe evaporates due to the heat of the exhaust gas and is discharged to the outside of the system as water vapor. This makes it possible to increase the amount of water vapor discharged from at least one of the first water tank, the second water tank and the aggregation tank to the outside of the system.

According to the fuel cell system according to the present invention, the amount of drain water generated can be controlled.

It is a block diagram which shows an example of the whole structure of the fuel cell system in 1st Embodiment of this invention. It is a block diagram which shows an example of the whole structure of the fuel cell system in 2nd Embodiment of this invention.

[First Embodiment]
<Fuel cell system>
As shown in FIG. 1, the fuel cell system 10 according to the first embodiment of the present invention includes a vaporizer 12, a reformer 14, a combustor 16, a first fuel cell stack 22, and a second fuel cell stack 24. , 1st water tank 32, 2nd water tank 34, shunt valve 44A, 44B, cooling mechanism 52, 54, pump 62, flow rate adjusting mechanism 67, control device 68, and aggregation tank 76.

(Vaporizer)
One end of the raw material gas pipe P1, which is a pipe through which the raw material gas flows, is connected to the vaporizer 12. A flow rate adjusting mechanism 67 for adjusting the flow rate of the raw material gas supplied to the vaporizer 12 is provided in the middle of the raw material gas pipe P1. As the flow rate adjusting mechanism 67, a flow rate adjusting valve is used as an example.

Further, one end of the water supply pipe P2, which is a pipe through which water flows, is connected to the vaporizer 12, and the other end of the water supply pipe P2 is connected to the aggregation tank 76. Water is stored in the aggregation tank 76.

The pump 62 pumps water from the aggregation tank 76 via the water supply pipe P2. Then, the pump 62 supplies the pumped water to the vaporizer 12 via the water supply pipe P2 to supply the water to the vaporizer 12.

The vaporizer 12 vaporizes the water supplied from the water supply pipe P2. Heat from the combustor 16 or the like is used for vaporization.

The vaporizer 12 supplies the raw material gas and steam to the reformer 14 by sending the raw material gas and steam to the reformer 14 via the pipe P3.

(Reformer)
The reformer 14 steam reforms the raw material gas to generate a reformed gas. One end of the pipe P3 is connected to the reformer 14. As a result, the raw material gas and steam are supplied to the reformer 14 through the pipe P3.

When methane, which is an example of a raw material gas, is steam reformed in the reformer 14, carbon monoxide and hydrogen are produced by the reaction of the following formula (1).
CH ₄ + H ₂ O → CO + 3H ₂ ... (1)

Further, when carbon monoxide is shift reformed, hydrogen and carbon dioxide are produced by the reaction of the following formula (2).
CO + H ₂ O → H ₂ + CO ₂ ... (2)

In this embodiment, methane is adopted as an example of the raw material gas, but the gas is not particularly limited as long as it can be reformed, and a hydrocarbon fuel can be used. Examples of the hydrocarbon fuel include natural gas, LP gas (liquefied petroleum gas), coal reforming gas, and lower hydrocarbon gas. Examples of the lower hydrocarbon gas include lower hydrocarbons having 4 or less carbon atoms such as methane, ethane, ethylene, propane, and butane, and methane used in the present embodiment is preferable. The hydrocarbon fuel may be a mixture of the above-mentioned lower hydrocarbon gas, and the above-mentioned lower hydrocarbon gas is a gas such as natural gas, city gas, LP gas, or biogas. May be good. Further, the raw material gas may be a mixed gas thereof.

One end of the reforming gas supply pipe P4 is connected to the reformer 14. The other end of the reformed gas supply pipe P4 is connected to an anode (fuel electrode, not shown) in the first fuel cell stack 22. As a result, the reforming gas generated by the reformer 14 is supplied to the first fuel cell stack 22 through the reforming gas supply pipe P4. The reformed gas contains unreacted methane, carbon dioxide and hydrogen produced by the reformer 14, unreacted carbon monoxide, steam and the like.

(Fuel cell cell stack)
The first fuel cell stack 22 is, for example, a solid oxide-based fuel cell stack, and has a plurality of stacked fuel cell cells (not shown). Each fuel cell has an electrolyte layer and a cathode (air electrode, not shown) and an anode laminated on the front and back surfaces of the electrolyte layer, respectively. The first fuel cell stack 22 may be a molten carbonate type fuel cell stack.

One end of the oxide gas pipe P5, which is a pipe through which the oxide gas flows, is connected to the cathode of the first fuel cell stack 22. Oxidizing gas (for example, air) is supplied to the cathode via the oxidizing gas tube P5. At the cathode, as shown in the following equation (3), oxygen in the oxidizing gas reacts with electrons to generate oxygen ions. The generated oxygen ions reach the anode through the electrolyte layer.

1 / 2O ₂ + 2e ⁻ → O ^2-・ ・ ・ (3)

On the other hand, at the anode, as shown in the following equations (4) and (5), oxygen ions that have passed through the electrolyte layer react with hydrogen and carbon monoxide, which are fuel gases in the reformed gas, and water ( Water vapor), carbon dioxide and electrons are generated. The electrons generated at the anode move from the anode to the cathode through an external circuit to generate electricity in each fuel cell. Each fuel cell cell generates heat during power generation.

^{_{H 2 + O 2- → H 2}} O + 2e - ··· (4)

_{^{CO + O 2- → CO 2 +}} 2e - ··· (5)

One end of the anode off gas pipe P6, which is a pipe through which the anode off gas flows, is connected to the anode of the first fuel cell stack 22, and the anode off gas is discharged to the anode off gas pipe P6. The anode off-gas contains unreacted hydrogen, unreacted carbon monoxide, carbon dioxide, water vapor and the like.

One end of the cathode off gas pipe P7, which is a pipe through which the cathode off gas flows, is connected to the cathode of the first fuel cell stack 22, and the cathode off gas is discharged to the cathode off gas pipe P7. The cathode off gas contains unreacted oxidizing gas and the like.

The other end of the anode off-gas pipe P6 is inserted into the first water tank 32, and the other end of the cathode off-gas pipe P7 is connected to the cathode (not shown) of the second fuel cell stack 24. A cooling mechanism 52, which will be described later, is provided in the middle portion of the anode off-gas pipe P6.

The configuration of the second fuel cell stack 24 is the same as that of the first fuel cell stack 22, and detailed description thereof will be omitted. However, as described above, the cathode of the second fuel cell stack 24 has a cathode off gas pipe P7. One end of is connected. Further, one end of the regenerated gas pipe P8, which will be described later, is connected to the anode of the second fuel cell stack 24.

Further, one end of the cathode off gas pipe P11, which is a pipe through which the cathode off gas flows, is connected to the cathode of the second fuel cell stack 24, and the cathode off gas is discharged to the cathode off gas pipe P11. The cathode-off gas includes unreacted oxidizing gas and the like, and the cathode-off gas is supplied to the combustor 16 via the cathode-off gas pipe P11.

One end of the anode off gas pipe P13, which is a pipe through which the anode off gas flows, is connected to the anode of the second fuel cell stack 24, and the anode off gas is discharged to the anode off gas pipe P13. The anode off gas contains unreacted hydrogen, unreacted carbon monoxide, carbon dioxide, water vapor and the like, and the anode off gas is supplied to the combustor 16 via the anode off gas pipe P13.

(Combustor)
The combustor 16 uses the used gas supplied from the cathode and the anode of the second fuel cell stack 24 for incineration. One end of the exhaust pipe P12 is connected to the combustor 16, and the exhaust gas after combustion is sent to the exhaust pipe P12. An intermediate portion of the exhaust pipe P12 is arranged in the vaporizer 12, and in the vaporizer 12, water is vaporized by the heat of the exhaust pipe P12.

(1st water tank)
The first water tank 32 is an intermediate gas tank in which the anode off gas discharged from the anode of the first fuel cell stack 22 flows in through the anode off gas pipe P6. An overflow pipe P15 is connected to the first water tank 32. The overflow pipe P15 sends the condensed water to the collecting tank 76 when the water level of the condensed water stored in the first water tank 32 reaches a certain height.

The gas from which water vapor and the like have been removed in the first water tank 32 flows into the anode of the second fuel cell stack 24 as regenerated gas via the regenerated gas pipe P8.

(2nd water tank)
The second water tank 34 is an exhaust gas tank in which the exhaust gas sent out from the combustor 16 flows in through the exhaust pipe P12. The other end side of the exhaust pipe P12 whose one end is connected to the combustor 16 branches into two flow paths P12A and P12B. The flow path P12A is provided with a flow dividing valve 44A and a cooling mechanism 54, and the end portion of the flow path P12A is inserted into the water tank 34. The cooling mechanism 54 is provided on the downstream side of the flow dividing valve 44A. Further, the flow path P12B is provided with a flow dividing valve 44B, and the end portion of the flow path P12B is open to the outside air. Further, the other end of the flow path P12C whose one end is inserted into the water tank 34 is connected to the flow path P12B. The flow dividing valves 44A and 42B are examples of bypass valves in the present invention.

An overflow pipe P14 is connected to the second water tank 34. The overflow pipe P14 sends the condensed water to the collecting tank 76 when the water level of the condensed water stored in the second water tank 34 reaches a certain height.

(Integrated tank)
The aggregation tank 76 is provided at a position lower than the first water tank 32 and the second water tank 34, and has an overflow pipe P15 connected to the first water tank 32 and an overflow pipe P14 connected to the second water tank 34. Is inserted.

A partition plate 76A and a water level sensor 76S are provided inside the aggregation tank 76. The partition plate 76A is joined to the inside of the aggregation tank 76 so as to form two air chambers in which the overflow pipes P15 and 14 are inserted into the aggregation tank 76, respectively. More specifically, the upper end surface and the side end surface of the partition plate 76A are joined to the inner side surface of the aggregation tank 76, and the lower end surface of the partition plate 76A is arranged below the predetermined water level lower limit value. As a result, the lower end of the partition plate 76A is inserted into the condensed water so that the gases in the two air chambers do not mix.

The water level sensor 76S can detect the water level in the aggregation tank 76 in order to maintain the amount of water in the aggregation tank 76 within a predetermined upper limit value and lower limit value. In the aggregation tank 76, the end portion of the water supply pipe P2 is connected below the lower limit position of the water level. The water supply pipe P2 sends the water in the aggregation tank 76 to the vaporizer 12 by driving the pump 62. The lower ends of the overflow pipes P15 and 14 are arranged above the upper limit of the water level of the water level sensor 32S.

The predetermined lower limit value in the water level sensor 76S is appropriately determined by, for example, the amount of reformed water required for starting the fuel cell system 10 and the amount of reformed water required for increasing the amount of power generation.

(Cooling mechanism)
The cooling mechanism 52 is a heat exchanger that cools the anode off gas flowing through the anode off gas pipe P6. The cooling mechanism 52 cools the anode off gas by exchanging heat between, for example, the oxidation gas flowing through the oxide gas pipe P5 and the anode off gas flowing through the anode off gas pipe P6. In the first water tank 32, the water condensed and obtained by the cooling operation at the time of driving the cooling mechanism 52 is discharged and stored.

Similarly, the cooling mechanism 54 is a heat exchanger that cools the exhaust gas flowing through the flow path P12A in the exhaust pipe P12. The cooling mechanism 54 cools the exhaust gas by exchanging heat between, for example, the raw material gas flowing through the raw material gas pipe P1 and the exhaust gas flowing through the flow path P12A. In the second water tank 34, the water condensed and obtained by the cooling operation at the time of driving the cooling mechanism 54 is discharged and stored.

(Control device)
The control device 68 is electrically connected to the first fuel cell stack 22, the second fuel cell stack 24, the water level sensor 76S, the divergence valves 44A and 44B, the cooling mechanisms 52 and 54, the pump 62, and the flow rate adjusting mechanism 67. ing. The control device 68 and the first fuel cell stack 22 are connected via a power conditioner that controls current and the like. The same applies to the control device 68 and the second fuel cell stack 24.

Further, the control device 68 can adjust the driving state of the cooling mechanisms 52 and 54 based on the water level information of the aggregation tank 76 received from the water level sensor 76S.

Further, the control device 68 can adjust the open / closed state of the flow dividing valves 44A and 44B based on the water level information of the aggregation tank 76 received from the water level sensor 76S.

Further, the control device 68 can adjust the driving state of the pump 62 based on the water level information of the aggregation tank 76 received from the water level sensor 76S.

Further, the control device 68 can adjust the amount of power generation in the first fuel cell stack 22 and the second fuel cell stack 24 based on the water level information of the aggregation tank 76 received from the water level sensor 76S.

Further, the control device 68 can control the flow rate adjusting mechanism 67 based on the water level information of the aggregation tank 76 received from the water level sensor 76S to adjust the input amount of the raw material gas to the vaporizer 12.

<Action / effect>
In the fuel cell system 10 according to the first embodiment, the water supplied from the water supply pipe P2 is consumed by the reforming reaction of the reformer 14 [Equation (1) and (2)]. Further, water is generated by the power generation of the first fuel cell stack 22 and the second fuel cell stack 24 [Equation (4)]. When the current value is high, most of the hydrogen generated in the reformer 14 is consumed by power generation, so that the amount of water consumed in the reformer 14 is compared with the first fuel cell stack 22 and the second fuel cell stack 22. The amount of water produced by the fuel cell stack 24 is larger. Therefore, the water in the system increases through the reforming reaction and the power generation reaction.

The water produced by the power generation reaction circulates in the system. A part of it is stored in the first water tank 32 and supplied to the aggregation tank 76. Others are stored in the second water tank 34 and supplied to the aggregation tank 76. The water supplied to the aggregation tank 76 is charged into the water supply pipe P2 and consumed again by the reforming reaction.

In order to reduce the water (liquid phase) in the system without discharging it to the outside of the system, the water is discharged "as water vapor" from the exhaust pipe P12 to the outside of the system. In the fuel cell system 10, the control device 68 appropriately assembles the first fuel cell stack 22, the second fuel cell stack 24, the divergence valves 44A and 44B, the cooling mechanisms 52 and 54, the pump 62, and the flow rate adjusting mechanism 67. By controlling it together, the amount of water vapor discharged to the outside of the system is adjusted. As a result, the water (liquid phase) in the system can be reduced without being discharged to the outside of the system. The amount of water in the system is determined by the amount of water in the aggregation tank 76.

Specifically, when the amount of water in the aggregation tank 76 is small (when the water level reaches the lower limit of the water level sensor 76S), the control device 68 determines that there is insufficient water in the system and increases the amount of power generation. And increase the amount of condensed water in the aggregation tank 76. Alternatively, the cooling intensity of the cooling mechanisms 52 and 54 is strengthened to increase the amount of condensed water charged into the water tanks 32 and 34, and the amount of condensed water in the aggregation tank 76 is increased. This makes it possible to secure the reformed water required at the time of starting the system, for example.

The cooling mechanism 52 cools the anode off gas by exchanging heat between the oxidation gas flowing through the oxide gas pipe P5 and the anode off gas flowing through the anode off gas pipe P6. In order to control the cooling intensity of the cooling mechanism 52, a bypass path and a control valve (not shown) are provided in the anode off-gas pipe P6, and the amount of anode-off gas "heat exchanged" with the oxidation gas flowing through the oxide gas pipe P5 and "heat" are provided. Adjust the amount of anode off gas that is not replaced.

Also in the cooling mechanism 54, a bypass (not shown) is provided in the flow path P12A. As a result, the amount of exhaust gas "heat exchanged" with the raw material gas flowing through the raw material gas pipe P1 and the amount of exhaust gas "not heat exchanged" are adjusted.

As the cooling mechanisms 52 and 54, in addition to the embodiment using the fluid in the system as described above, a cooling fan or cooling water outside the system drawn from the outside may be used. When using a cooling fan or cooling water, it is not necessary to provide a bypass path.

Further, when the amount of water in the aggregation tank 76 is large (when the water level reaches the upper limit of the water level sensor 76S), the control device 68 determines that there is excess water in the system and discharges water vapor from the exhaust pipe P12. Increase the amount to reduce the amount of condensed water in the aggregation tank 76. This makes it possible to reduce the amount of water from the system without using a drain pipe for discharging the condensed water in the aggregation tank 76.

The method of adjusting the amount of condensed water in the aggregation tank 76 will be described for each control target by the control device 68.

First, an example of a method of increasing the amount of power generation to increase the amount of condensed water in the aggregation tank 76 will be described.

(Adjustment of raw material gas input)
The control device 68 can control the flow rate adjusting mechanism 67 based on the water level information of the aggregation tank 76 received from the water level sensor 76S to adjust the input amount of the raw material gas to the vaporizer 12.

For example, when the control device 68 obtains information from the water level sensor 76S that the water level (water amount) of the aggregation tank 76 has reached a predetermined lower limit value, the control device 68 controls the flow rate adjusting mechanism 67 to input the raw material gas to the vaporizer 12. Adjust the amount. Specifically, the input amount of the raw material gas is increased, and the input amount of the reforming water, the power generation amount in the first fuel cell stack 22, and the second fuel cell stack 24 are appropriately increased according to the increase in the raw material gas. Increase the amount of power generation and the amount of oxide gas (air) input to the first fuel cell stack 22. As a result, the amount of the anode off gas and the amount of water vapor contained in the anode off gas in the first fuel cell stack 22 are increased. Then, the amount of water vapor charged into the first water tank 32 can be increased. Therefore, the amount of condensed water condensed in the first water tank 32 and the amount of water stored in the concentrated tank 76 can be increased.

Next, an example of a method of increasing the amount of water vapor discharged from the exhaust pipe P12 to reduce the amount of condensed water in the aggregation tank 76 will be described.

(Control of cooling mechanism)
The control device 68 can adjust the driving state of the cooling mechanisms 52 and 54 based on the water level information of the aggregation tank 76 received from the water level sensor 76S.

As an example, when the control device 68 receives information from the water level sensor 76S that the water level (water amount) of the aggregation tank 76 has reached a predetermined upper limit value, the control device 68 controls the cooling mechanism 52 to weaken the cooling intensity. Or stop the drive. As a result, the water vapor contained in the anode off gas flowing through the anode off gas pipe P6 is suppressed from condensing. Therefore, the amount of condensed water charged into the first water tank 32 and the amount of water stored in the concentrated tank 76 can be reduced.

The uncondensed water vapor charged into the first water tank 32 is charged into the second fuel cell stack 24 via the regenerated gas pipe P8, except for a part condensed inside the first water tank 32. It is discharged to the outside of the system via the combustor 16 and the exhaust pipe P12. Therefore, the amount of water stored in the first water tank 32 can be reduced.

As another example, when the control device 68 receives information from the water level sensor 76S that the water level (water amount) of the aggregation tank 76 has reached a predetermined upper limit value, the control device 68 controls the cooling mechanism 54 to weaken the cooling intensity. Or stop the drive. As a result, the condensation of water vapor contained in the exhaust gas flowing through the flow path P12A in the exhaust pipe P12 is suppressed. Therefore, the amount of condensed water charged into the second water tank 34 and the amount of water stored in the concentrated tank 76 can be reduced.

The uncondensed water vapor charged into the second water tank 34 is discharged to the outside of the system via the flow paths P12C and P12B except for a part condensed inside the second water tank 34. Therefore, the amount of water stored in the water tank 34 can be reduced.

(Control of shunt valve)
The control device 68 can adjust the open / closed state of the flow dividing valves 44A and 44B based on the water level information of the aggregation tank 76 received from the water level sensor 76S.

When the control device 68 obtains information from the water level sensor 76S that the water level (water amount) of the aggregation tank 76 has reached a predetermined upper limit value, the control device 68 controls the flow distribution valves 44A and 44B to control the second water tank 34 for exhaust gas. Adjust the inflow to. Specifically, for example, the diversion valve 44A is closed and the diversion valve 44B is opened. As a result, the exhaust gas and the water vapor contained in the exhaust gas are exhausted to the outside of the system and are suppressed from flowing into the second water tank 34. Therefore, the amount of condensed water condensed inside the second water tank 34 can be reduced.

The control device 68 does not need to completely close the diversion valve 44A and completely open the diversion valve 44B. For example, if the opening degree of the diversion valve 44A and the diversion valve 44B is adjusted so that at least a part of the exhaust gas flowing through the exhaust pipe P12 is directly discharged from the flow path P12B without flowing into the second water tank 34. good.

(Pump control)
The control device 68 can adjust the driving state of the pump 62 based on the water level information of the aggregation tank 76 received from the water level sensor 76S.

For example, when the control device 68 obtains information from the water level sensor 76S that the water level (water amount) of the aggregation tank 76 has reached a predetermined upper limit value, the control device 68 controls the pump 62 to control the pump 62 from the aggregation tank 76 to the water supply pipe P2. Adjust the amount of condensed water discharged. Specifically, the driving force of the pump 62 is increased, and the amount of condensed water discharged from the aggregation tank 76 is increased. As a result, the amount of water stored in the aggregation tank 76 can be reduced.

(Control of fuel cell stack)
The control device 68 can adjust the power generation amount of at least one of the first fuel cell stack 22 and the second fuel cell stack 24 based on the water level information of the aggregation tank 76 received from the water level sensor 76S.

For example, when the control device 68 obtains information from the water level sensor 76S that the water level (water amount) of the aggregation tank 76 has reached a predetermined upper limit value, the control device 68 controls the first fuel cell cell stack 22 to control the first fuel cell. The amount of power generated by the cell stack 22 is adjusted. Specifically, the amount of power generated by the first fuel cell stack 22 is reduced, and the amount of anode-off gas and the amount of water vapor contained in the anode-off gas are reduced. As a result, the amount of water vapor charged into the first water tank 32 can be reduced. Therefore, the amount of condensed water condensed in the first water tank 32 and the amount of condensed water flowing into the concentrated tank 76 can be reduced.

At this time, by increasing the amount of power generation in the second fuel cell stack 24, it is possible to suppress a decrease in the amount of power generation in the entire fuel cell system.

As another example, when the control device 68 obtains information from the water level sensor 32S that the water level (water amount) of the water tank 34 has reached a predetermined upper limit value, the control device 68 controls the second fuel cell stack 24 to obtain a second fuel cell stack 24. 2 Adjust the amount of power generated by the fuel cell stack 24. Specifically, the amount of power generated by the second fuel cell stack 24 is reduced, and the amount of anode-off gas in the second fuel cell stack 24 and the amount of water vapor contained in the anode-off gas are reduced. As a result, the amount of water vapor charged into the water tank 34 can be reduced.

When the power generation amount of the second fuel cell stack 24 is reduced, the reduction of the power generation amount of the entire fuel cell system 10 can be suppressed by increasing the power generation amount of the first fuel cell stack 22. However, when the amount of power generation in the first fuel cell stack 22 is increased, the amount of water vapor of the anode off gas discharged from the first fuel cell stack 22 increases. Therefore, in order to suppress an increase in the amount of water vapor flowing into the water tank 34, for example, the control device 68 closes the divergence valve 44A and opens the divergence valve 44B to suppress the inflow of water vapor into the water tank 34.

The control device 68 controls the flow rate adjusting mechanism 67, the cooling mechanisms 52 and 54, the divergence valves 44A and 44B, the pump 62, the first fuel cell stack 22, and the second fuel cell. The control of the stack 24 can be executed in any combination. By combining these controls, the effect of adjusting the amount of condensed water in the aggregation tank 76 can be enhanced. Alternatively, the control device 68 may perform any control independently.

As described above, according to the fuel cell system 10 according to the first embodiment, the control device 68 includes a flow rate adjusting mechanism 67, a cooling mechanism 52, 54, a divergence valve 44A, 44B, a pump 62, and a first fuel cell stack. By controlling 22 and the second fuel cell stack 24, the amount of water in the system can be adjusted.

Further, in the fuel cell system 10, an overflow pipe P15 is connected to the first water tank 32, and when the water level of the condensed water in the first water tank 32 reaches a certain height, the condensed water is collected in the concentrated tank 76. Is sent to. Similarly, the overflow pipe P14 is connected to the second water tank 34, and when the water level of the condensed water in the second water tank 34 reaches a certain height, the condensed water is sent to the aggregation tank 76. Therefore, drainage from the first water tank 32 and the second water tank 34 can be eliminated.

Further, the control device 68 adjusts the amount of condensed water charged into the first water tank 32 and the second water tank 34. As a result, the amount of condensed water flowing from the first water tank 32 and the second water tank 34 into the aggregation tank 76 can be reduced. Further, the control device 68 adjusts the amount of water vapor charged into the second water tank 34. As a result, the amount of condensed water flowing from the second water tank 34 into the aggregation tank 76 can be reduced.

Further, the control device 68 adjusts the amount of condensed water discharged from the aggregation tank 76 to the water supply pipe P2. As a result, the amount of water in the aggregation tank 76 can be maintained within a predetermined range. Therefore, the drainage from the aggregation tank 76 can be reduced. Further, drainage from the centralized tank 76 can be eliminated, and drainage equipment and construction for drainage can be omitted.

In the fuel cell system 10 according to the first embodiment, a cooling mechanism 54 is provided in the flow path P12A of the exhaust pipe P12 to adjust the amount of condensed water charged into the second water tank 34. The form is not limited to this. Even if the cooling mechanism 54 is not provided, the amount of water vapor charged into the second water tank 34 may be adjusted by using the flow dividing valves 44A and 44B.

Further, in the fuel cell system 10, a cooling mechanism 52 is provided in the anode off-gas pipe P6 to adjust the amount of condensed water charged into the first water tank 32, but the embodiment of the present invention is not limited to this. Even if the cooling mechanism 52 is not provided, the amount of water vapor charged into the second water tank 34 may be adjusted by using the flow dividing valves 44A and 44B. Alternatively, the amount of condensed water charged into the second water tank 34 may be adjusted by using the cooling mechanism 54.

As described above, the fuel cell system 10 may be provided with any of the cooling mechanisms 52 and 54 and the shunt valve 44A and the shunt valve 44B. By providing any of these, the amount of water stored in the aggregation tank 76 can be adjusted.

[Second Embodiment]
<Fuel cell system>
The fuel cell system 70 according to the second embodiment shown in FIG. 2 is first implemented in that the second water tank 34, the aggregation tank 76, the cooling mechanism 54, and the diversion valves 44A and 44B shown in FIG. 1 are not provided. It is different from the fuel cell system 10 according to the embodiment. Further, in the fuel cell system 70, the water level sensor 32S is provided in the first water tank 32, and the end portion of the water supply pipe P2 is connected below the lower limit position of the water level of the first water tank 32.

In the second embodiment, the same reference numerals are used for the same configuration as the fuel cell system 10 according to the first embodiment, and the description thereof will be omitted. Further, the same effect due to the same configuration as the fuel cell system 10 according to the first embodiment will not be described.

(Control device)
The control device 68 in the fuel cell system 70 is electrically connected to the first fuel cell stack 22, the second fuel cell stack 24, the water level sensor 32S, the cooling mechanism 52, the pump 62, and the flow rate adjusting mechanism 67.

Further, the control device 68 can adjust the driving state of the cooling mechanism 52 based on the water level information of the first water tank 32 received from the water level sensor 32S.

Further, the control device 68 can adjust the driving state of the pump 62 based on the water level information of the first water tank 32 received from the water level sensor 32S.

Further, the control device 68 can adjust the amount of power generation in the first fuel cell stack 22 and the second fuel cell stack 24 based on the water level information of the first water tank 32 received from the water level sensor 32S.

Further, the control device 68 can control the flow rate adjusting mechanism 67 based on the water level information of the first water tank 32 received from the water level sensor 32S to adjust the input amount of the raw material gas to the vaporizer 12.
<Action / effect>

(Adjustment of raw material gas input)
The control device 68 can control the flow rate adjusting mechanism 67 based on the water level information of the first water tank 32 received from the water level sensor 32S to adjust the input amount of the raw material gas to the vaporizer 12.

For example, when the control device 68 obtains information from the water level sensor 32S that the water level (water amount) of the first water tank 32 has reached a predetermined lower limit value, the control device 68 controls the flow rate adjusting mechanism 67 to control the raw material gas for the vaporizer 12. Adjust the input amount of. Specifically, the input amount of the raw material gas is increased, and the input amount of the reforming water, the power generation amount in the first fuel cell stack 22, and the second fuel cell stack 24 are appropriately increased according to the increase in the raw material gas. Increase the amount of power generation and the amount of oxide gas (air) input to the first fuel cell stack 22. As a result, the amount of the anode off gas and the amount of water vapor contained in the anode off gas in the first fuel cell stack 22 are increased. Then, the amount of water vapor charged into the first water tank 32 can be increased. Therefore, the amount of water stored in the first water tank 32 can be increased.

(Control of cooling mechanism)
The control device 68 can adjust the driving state of the cooling mechanism 52 based on the water level information of the first water tank 32 received from the water level sensor 32S.

As an example, when the control device 68 receives information from the water level sensor 32S that the water level (water amount) of the first water tank 32 has reached a predetermined upper limit value, the control device 68 controls the cooling mechanism 52 to weaken the cooling intensity. Or stop the drive. As a result, the water vapor contained in the anode off gas flowing through the anode off gas pipe P6 is suppressed from condensing. Therefore, the amount of condensed water charged into the first water tank 32 can be reduced.

The uncondensed water vapor charged into the first water tank 32 is charged into the second fuel cell stack 24 via the regenerated gas pipe P8, except for a part condensed inside the first water tank 32. .. Therefore, the amount of condensed water stored in the first water tank 32 can be reduced.

(Pump control)
The control device 68 can adjust the driving state of the pump 62 based on the water level information of the first water tank 32 received from the water level sensor 32S.

For example, when the control device 68 obtains information from the water level sensor 32S that the water level (water amount) of the first water tank 32 has reached a predetermined upper limit value, the control device 68 controls the pump 62 to supply water from the first water tank 32. Adjust the amount of condensed water discharged to the tube P2. Specifically, the driving force of the pump 62 is increased, and the amount of condensed water discharged from the first water tank 32 is increased. As a result, the amount of condensed water inside the first water tank 32 can be reduced.

(Control of fuel cell stack)
The control device 68 can adjust the amount of power generation in the first fuel cell stack 22 and the second fuel cell stack 24 based on the water level information of the first water tank 32 received from the water level sensor 32S.

For example, when the control device 68 obtains information from the water level sensor 32S that the water level (water amount) of the first water tank 32 has reached a predetermined upper limit value, the control device 68 controls the first fuel cell stack 22 to control the first fuel cell stack 22. The amount of power generated by the fuel cell stack 22 is adjusted. Specifically, the amount of power generated by the first fuel cell stack 22 is reduced, and the amount of anode-off gas and the amount of water vapor contained in the anode-off gas are reduced. As a result, the amount of water vapor charged into the first water tank 32 can be reduced. Therefore, the amount of condensed water condensed in the first water tank 32 can be reduced.

At this time, by increasing the amount of power generation in the second fuel cell stack 24, it is possible to suppress a decrease in the amount of power generation in the entire fuel cell system.

The control device 68 appropriately combines the control of the flow rate adjusting mechanism 67, the control of the cooling mechanism 52, the control of the pump 62, the control of the first fuel cell stack 22, and the control of the second fuel cell stack 24. Can be executed. By combining these controls, the effect of adjusting the amount of condensed water in the first water tank 32 can be enhanced. Alternatively, the control device 68 may perform any control independently.

As described above, according to the fuel cell system 70 according to the second embodiment, the control device 68 adjusts the amount of condensed water charged into the first water tank 32. Further, the control device 68 adjusts the amount of condensed water discharged from the first water tank 32 to the water supply pipe P2. As a result, the amount of water in the first water tank 32 can be maintained within a predetermined range. Therefore, the drainage from the first water tank 32 can be reduced. Further, the drainage from the first water tank 32 can be eliminated, and the drain pipe for drainage can be omitted. As a result, plumbing work can be omitted.

In the fuel cell system 70 according to the second embodiment, the amount of condensed water charged into the water tank 32 is adjusted by the cooling mechanism 52, and the amount of condensed water discharged from the water tank 32 is adjusted by the pump 62. The embodiment of the present invention is not limited to this. For example, the fuel cell system 70 may include any of the cooling mechanism 52 and the pump 62. If any of these is provided, the amount of condensed water in the water tank 32 can be reduced.

Further, in the fuel cell system 70 according to the second embodiment, the exhaust gas discharged from the combustor 16 is directly exhausted from the exhaust pipe P12 to the outside of the system, but the embodiment of the present invention is not limited to this. For example, the second water tank 34 in the first embodiment may be provided to condense the water vapor contained in the exhaust gas. In this case, it is preferable to further provide the flow dividing valves 44A and 44B and the cooling mechanism 54 as in the first embodiment. Further, it is more preferable to connect the second water tank 34 with a water supply path for supplying the condensed water in the second water tank 34 to the vaporizer 12.

Further, in the fuel cell system 70 according to the first embodiment, only the water supply pipe P2 is connected to the aggregation tank 76 as a discharge path for condensed water, but the embodiment of the present invention is not limited to this. For example, one end of a water droplet supply pipe (not shown) may be connected to the aggregation tank 76, and the other end of the water droplet supply pipe may be connected to the flow path P12B in the exhaust pipe P12. The water drop supply pipe drops and supplies the condensed water discharged from the aggregation tank 76 to the exhaust pipe P12. By providing the water drop supply pipe, the control device 68 can control the amount of condensed water dropped on the exhaust pipe P12.

At this time, for example, when the amount of water in the aggregation tank 76 reaches a predetermined upper limit value, the control device 68 increases the amount of condensed water dropped on the exhaust pipe P12. The condensed water dropped on the exhaust pipe P12 evaporates due to the heat of the exhaust gas and is discharged to the outside of the system as water vapor. As a result, the amount of water vapor discharged from the aggregation tank 76 to the outside of the system can be increased. Such a water drop supply pipe can also be applied to the water tank 32 of the second embodiment. Alternatively, it can be provided in at least one of the water tanks 32 and 34 in a configuration that does not include the aggregation tank 76.

Further, in each of the above embodiments, the fuel cell stack is composed of two stages, but the embodiment of the present invention is not limited to this. For example, a fuel cell stack having an arbitrary number of stages of three or more stages may be used.

Further, the fuel cell system according to each of the above embodiments is a multi-stage fuel cell system including the first fuel cell stack 22 and the second fuel cell stack 24, but the embodiment of the present invention is the same. Not limited to. For example, the second fuel cell stack 24, the cathode off gas pipe P11 and the anode off gas pipe P13 shown in FIG. 1 are omitted, the regenerated gas pipe P8 is connected to the reformed gas supply pipe P4, and the regenerated gas pipe P8 is branched. A circulating fuel cell system may be used in which the pipe is connected to the combustor 16 and the cathode off gas pipe P7 is connected to the combustor 16.

Further, in each of the above embodiments, a reformer 14 for generating fuel gas is provided, but the embodiment of the present invention is not limited to this. For example, steam and raw material gas may be supplied to the first fuel cell stack 22 without providing the reformer 14. In this case, the reforming reaction is performed in the first fuel cell stack 22. As described above, the "reforming unit" in the present invention refers to both the reformer 14 provided separately from the fuel cell and the portion where the reforming reaction is performed in the fuel cell. As described above, the present invention can be carried out in various embodiments.

10, 70 Fuel cell system 12 Vaporizer 14 Reformer (reformer)
16 Combustor 22 1st fuel cell cell stack (fuel cell)
24 Second fuel cell cell stack (second fuel cell)
32 1st water tank 34 2nd water tank 44A Flow valve (bypass valve)
44B shunt valve (bypass valve)
52 Cooling mechanism (first cooling mechanism)
54 Cooling mechanism (second cooling mechanism)
67 Flow rate adjustment mechanism 68 Control device 76 Aggregation tank 76S Water level sensor 76A Partition plate P2 Water supply pipe

Claims (17)

A vaporizer that vaporizes the water supplied from the water supply pipe to generate water vapor,
A reforming unit that steam reforms the raw material gas using the steam generated by the vaporizer to generate fuel gas,
A fuel cell that generates electricity by reacting the fuel gas generated in the reforming section with the oxidizing gas,
Condensed water in which water vapor contained in the off-gas discharged from the fuel electrode of the fuel cell is condensed is stored, and the first water tank to which the water supply pipe is connected and
A control device that maintains the amount of water in the first water tank within a predetermined range by controlling the amount of power generated by the fuel cell and adjusting the amount of water vapor charged into the first water tank.
Fuel cell system with. The control device adjusts at least one of the amount of condensed water charged into the first water tank and the amount of condensed water discharged from the first water tank to the water supply pipe to adjust the amount of water in the first water tank. The fuel cell system according to claim 1, which is maintained within a predetermined range. According to claim 1, the control device can reduce the amount of water vapor contained in the off-gas and reduce the amount of water vapor charged into the first water tank by reducing the amount of power generated by the fuel cell. Item 2. The fuel cell system according to Item 2. Claims 1 to claim that the control device can increase the amount of water vapor contained in the off-gas and increase the amount of water vapor charged into the first water tank by increasing the amount of power generated by the fuel cell. The fuel cell system according to any one of 3. The fuel cell is
The first fuel cell that generates power by reacting the fuel gas generated in the reforming unit with the oxide gas, and the unreacted fuel gas contained in the off-gas and the oxide gas react with each other to generate power. Equipped with 2 fuel cells
The control device controls the amount of power generation of at least one of the first fuel cell and the second fuel cell to adjust the amount of water vapor charged into the first water tank, according to claims 1 to 4. The fuel cell system according to any one item. The fuel cell system according to claim 5 , wherein the second fuel cell is arranged on the downstream side of the first water tank. By reducing the amount of power generated by the first fuel cell, the control device reduces the amount of water vapor contained in the off-gas to reduce the amount of water vapor charged into the first water tank, and the second fuel. The fuel cell system according to claim 6, wherein the reduction of the power generation amount is suppressed by increasing the power generation amount of the battery. A vaporizer that vaporizes the water supplied from the water supply pipe to generate water vapor,
A reforming unit that steam reforms the raw material gas using the steam generated by the vaporizer to generate fuel gas,
A fuel cell that generates electricity by reacting the fuel gas generated in the reforming section with the oxidizing gas,
A first water tank in which condensed water in which water vapor contained in the off-gas discharged from the fuel cell is condensed is stored, and
A combustor that burns the off-gas discharged from the fuel cell with the oxide off-gas discharged from the air electrode of the fuel cell.
A second water tank in which condensed water in which water vapor contained in the exhaust gas discharged from the combustor is condensed is stored, and
By controlling the power generation amount of the fuel cell and adjusting at least one of the amount of water vapor charged into the first water tank and the amount of water vapor charged into the second water tank, the amount of water in the first water tank or A control device that maintains the amount of water in the second water tank within a predetermined range, and
Fuel cell system with. The control device is
At least one of the amount of condensed water charged into the first water tank, the amount of condensed water discharged from the first water tank, the amount of condensed water charged into the second water tank, and the amount of condensed water discharged from the second water tank. To maintain the amount of water in the first water tank or the second water tank within a predetermined range.
The fuel cell system according to claim 8. A second cooling mechanism for cooling the exhaust gas on the upstream side of the second water tank and condensing the water vapor contained in the exhaust gas is provided.
The fuel cell system according to claim 8 or 9 , wherein the control device controls the second cooling mechanism to adjust the amount of condensed water charged into the second water tank. A bypass valve for exhausting the exhaust gas without passing through the second water tank is provided.
The fuel cell system according to any one of claims 8 to 10 , wherein the control device controls the bypass valve to adjust the amount of water vapor charged into the second water tank. The fuel cell is
The first fuel cell that generates power by reacting the fuel gas generated in the reforming unit with the oxide gas, and the unreacted fuel gas contained in the off-gas and the oxide gas react with each other to generate power. Equipped with 2 fuel cells
The control device controls the amount of power generation of at least one of the first fuel cell and the second fuel cell to adjust the amount of water vapor charged into the first water tank or the second water tank. 8. The fuel cell system according to any one of claims 11. The fuel cell system according to claim 12 , wherein the second fuel cell is arranged on the downstream side of the first water tank. A first cooling mechanism for cooling the off-gas upstream of the first water tank or in the first water tank to condense the water vapor contained in the off-gas is provided.
The fuel cell system according to any one of claims 1 to 13 , wherein the control device controls the first cooling mechanism to adjust the amount of condensed water charged into the first water tank. It is equipped with a flow rate adjustment mechanism that adjusts the input amount of the raw material gas.
The fuel cell system according to any one of claims 1 to 14 , wherein the control device controls the flow rate adjusting mechanism to adjust the amount of power generation. A combustor that burns the off-gas discharged from the fuel cell with the oxide off-gas discharged from the air electrode of the fuel cell.
An exhaust pipe that discharges the exhaust gas discharged from the combustor to the outside of the system,
A water droplet supply pipe for supplying the condensed water stored in the first water tank to the exhaust pipe is provided.
The fuel according to any one of claims 1 to 15 , wherein the control device controls the amount of condensed water supplied to the exhaust pipe to adjust the amount of condensed water discharged from the first water tank. Battery system. An exhaust pipe that discharges the exhaust gas discharged from the combustor to the outside of the system,
A water droplet supply pipe for supplying the condensed water stored in at least one of the first water tank and the second water tank to the exhaust pipe is provided.
The control device controls the amount of condensed water supplied to the exhaust pipe to adjust the amount of condensed water discharged from at least one of the first water tank and the second water tank, claims 8 to 13. The fuel cell system according to any one of the above items.

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