JP5501733B2 - Fuel cell system and its pure water replacement method - Google Patents

Description

  The present invention relates to a fuel cell system capable of replacing pure water (process water) used in circulation in the system, and a pure water replacement method.

  A household fuel cell system (power generation unit) includes a hydrogen production apparatus including a reformer that steam-reforms a hydrocarbon fuel (for example, city gas, LPG, kerosene, etc.) to generate hydrogen, and the generated hydrogen. Cell stack that generates a direct current from fuel and oxygen in the air by a fuel cell reaction, a power conditioner that converts the direct current generated in the fuel cell stack into an alternating current, and recovers heat generated in the fuel cell stack, etc. And a heat exchanger for exchanging heat with the hot water supply unit side.

  The fuel cell system (power generation unit) includes a pure water tank that stores pure water, and circulates and supplies pure water to each part of the system. Specifically, water necessary for steam reforming is supplied from the pure water tank to the reformer, while moisture is recovered from the off-gas of the fuel cell stack by a condenser and returned to the pure water tank. The water in the pure water tank is also circulated as cooling water for a fuel cell stack and the like, and heat recovery is performed by a heat exchanger.

By the way, as the above water, pure water (high purity water from which impurities have been removed by physical or chemical treatment of water) is used. However, when impurities derived from off-gas or cooling system are mixed in the circulation, It is necessary to maintain and manage the purity in the water tank because it causes deterioration of the reforming catalyst and the like.
For this reason, as described in Patent Document 1, an ion exchange resin is provided in the circulation path and filtered to remove impurities including metal ions.

JP 2006-040553 A

However, in the method of filtering with the ion exchange resin described in Patent Document 1, (1) increase in maintenance due to periodic exchange of the ion exchange resin, and (2) the conductivity rapidly increases when the ion exchange resin reaches the end of its life. (3) There are problems that there are impurities that cannot be filtered with ion exchange resins (such as bacteria).
Moreover, although patent document 1 describes performing control which replaces part or all of the water in a water tank, since it is necessary to operate a water supply pump for water replacement, the timing of replacement | exchange is performed. It is limited to “when the system starts operating, when it stops, or after a predetermined operating time”.

  In view of such a situation, the present invention eliminates the need for mounting a filtration device (ion exchange resin), and allows a simple replacement of pure water regardless of whether it is operating or stopped. It is an object of the present invention to provide a pure water replacement method.

In order to solve the above-described problems, the present invention provides a fuel cell system including a pure water tank that stores and circulates pure water in a system casing, and from the outside of the system casing to an upper portion of the pure water tank in the casing. Equipped with a water inlet that can inject pure water, a water outlet that can discharge pure water from the bottom of the water tank, and an open / close mechanism that can be operated from outside the system housing and that can open and close the water inlet and water outlet. The configuration.
Here, the opening / closing mechanism includes a water inlet opening / closing valve for opening / closing the water inlet and a drain opening / closing valve for opening / closing the water outlet.
The water inlet opening / closing valve and the water outlet opening / closing valve are interlocked with each other and have a phase difference in connection with each other. When the valve is opened, the water inlet opening / closing valve is opened, and then the water outlet opening / closing valve is opened and closed. At the time of valve operation, the drain opening / closing valve is closed and then the water injection opening / closing valve is closed.

Further, the pure water replacement method of the present invention is based on the premise that the fuel cell system includes a pure water tank that stores and circulates pure water in the system casing and circulates it. Inject pure water for replacement from the water injection port that can inject pure water into the upper part of the water, and in conjunction with the injection, discharge pure water from the drain outlet at the bottom of the pure water tank. Replace pure water.
Here, the injection start timing of pure water injected from the water injection port is set earlier than the drain start timing of pure water discharged from the drain port, and the injection end timing of pure water injected from the water injection port is Set later than the end timing of draining pure water discharged from the drain outlet.

  The “replacement” here does not need to replace all of the pure water in the circulation path, and it is sufficient if most of the pure water in the pure water tank can be replaced.

According to the present invention, it is possible to easily replace pure water from outside the system housing, regardless of whether the vehicle is in operation or stopped, in other words, while driving. Therefore, the user can also replace it, and the maintenance cost can be greatly reduced. Further, it is possible to reduce expensive ion exchange resins.
In addition, the timing for starting the injection of pure water injected from the water inlet is set earlier than the timing for starting the drain of pure water discharged from the water outlet, and the timing for ending the injection of pure water injected from the water inlet is set from the outlet. By setting later than the end timing of the drain of pure water to be discharged, excessive discharge can be prevented and replacement of pure water during operation can be performed more reliably without any trouble.

1 is a schematic configuration diagram of a fuel cell system showing an embodiment of the present invention. The figure which shows the structure with which a system housing | casing and a pure water tank are equipped in order to replace the pure water in a pure water tank Diagram showing how to replace pure water The figure which shows the structure of the system housing | casing and pure water tank in other embodiment. The figure which shows the replacement | exchange method of the pure water in other embodiment

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a schematic configuration diagram of a fuel cell system (power generation unit) showing an embodiment of the present invention.
A household fuel cell system (power generation unit) includes a hydrogen production apparatus (reformer) 2, a fuel cell stack 3, a power conditioner (PCS) 4, and a heat exchanger 5 in a system housing 1. It is prepared for.

  The hydrogen production apparatus 2 generates hydrogen (hydrogen-rich fuel gas containing H2 and CO2) by steam reforming a hydrocarbon fuel (for example, city gas, LPG, kerosene, etc.) using a reforming catalyst while steam is supplied. The reformer to be generated is the main component. In addition, a combustor (burner) 6 for heating a reformer for a reforming reaction (endothermic reaction) is provided. The fuel).

  Although not shown, the hydrogen production device 2 is also provided upstream of the reformer, and adsorbs or removes sulfur compounds contained in the hydrocarbon-based fuel before reforming using an adsorbent. A desulfurizer that converts and removes using a catalyst, and a CO shift reactor that is provided downstream of the reformer and that converts by-product CO in the reformed gas to residual steam by a shift catalyst to convert it into CO2 and H2. A CO selective oxidizer that selectively oxidizes CO slightly remaining in the gas after the shift reaction into CO2 by selectively oxidizing it with an air supply using a selective oxidation catalyst.

In the fuel cell stack 3, hydrogen (hydrogen-rich fuel gas) is supplied to the fuel electrode on one end side of the electrolyte layer, oxygen in the air is supplied to the air electrode on the other end side of the electrolyte layer, and hydrogen and oxygen A direct current is generated by a chemical reaction (exothermic reaction).
A power conditioner (PCS) 4 converts a direct current generated in the fuel cell stack 3 into an alternating current, and supplies the alternating current to a distribution board provided between a system power supply and a household load. The power conditioner 4 also has a function of controlling the amount of power generation by connecting the fuel cell to a system power supply and a load in the home. Thereby, the alternating current power from a system power supply and the alternating current power from the power conditioner 4 are supplied to the load in the home via the same distribution line.

The heat exchanger 5 constitutes a part of the cooling system of the fuel cell, collects heat generated in the fuel cell stack 3, and exchanges heat with the hot water supply unit (hot water storage unit).
The fuel cell system (power generation unit) also includes a pure water tank 7 for storing pure water (high-purity water from which impurities have been removed by physical or chemical treatment of water) and a pure water tank 7 in the system housing 1. A circulation path through which pure water in the water tank 7 is circulated and supplied.

Specifically, water necessary for steam reforming is supplied from a delivery port S at the bottom of the pure water tank 7 to the hydrogen production device (reformer) 2 by the pump 8, while the air electrode side of the fuel cell stack 3 is provided. Water is collected from the off-gas by the condenser 9 and returned to the pure water tank 7 from the return port R at the top of the pure water tank 7.
The water in the pure water tank 7 is also circulated as cooling water for the fuel cell stack 3 and the like, and heat is recovered by the heat exchanger 5. That is, pure water (cooling water) is sent to the cooler 11 of the fuel cell stack 3 from the outlet S at the bottom of the pure water tank 7 by the pump 10, and the water heated here is heated by the heat exchanger 5. After exchanging heat with water from the water, the water is returned into the pure water tank 7 from the return port R at the top of the pure water tank 7.

Here, the pure water tank 7 stores pure water (high-purity water). However, when it is circulated, it contains impurities derived from off-gas and the cooling system, thereby reducing the purity. Invite. For this reason, a user can replace the pure water in the pure water tank 7 regularly.
A configuration provided in the system housing 1 and the pure water tank 7 for exchanging pure water in the pure water tank 7 and a method for exchanging pure water based thereon will be described with reference to FIGS.

FIG. 2 schematically shows a system casing 1 of the fuel cell system (power generation unit) and a pure water tank 7 provided in the casing 1.
As shown in FIG. 1, the pure water tank 7 is formed with a delivery port S to the pure water circulation path at the bottom and a return port R from the pure water circulation path at the top. As shown in FIG. 2, the water injection port 12, the drainage port 13, and the overflow port 14 are formed.

The water injection port 12 is such that the other end of the pipe whose one end communicates with the upper part of the pure water tank 7 is led out from the system housing 1 horizontally or upward. Pure water can be injected into the upper part of the water tank 7.
The drain port 13 is configured such that the other end of the pipe whose one end communicates with the bottom of the pure water tank 7 is led out horizontally or downward to the outside of the system housing 1, and the pure water can be discharged from the bottom of the pure water tank 7. It is configured.

Here, the channel cross-sectional area a <b> 1 of the water inlet 12 is set larger than the channel cross-sectional area a <b> 2 of the drain port 13. In other words, the pipe diameter of the water inlet 12 is larger than the pipe diameter of the drain outlet 13.
The overflow port 14 is configured such that the other end of the pipe whose one end communicates with a predetermined overflow line position of the pure water tank 7 is led out of the system housing 1 horizontally or downwardly. Pure water is allowed to overflow when the surface exceeds a predetermined overflow line.

For the water injection port 12 and the drain port 13, on-off valves 15 and 16 are provided at positions outside the system housing 1 of the respective pipes. The water inlet opening / closing valve 15 and the water outlet opening / closing valve 16 can be operated from outside the system housing 1 and constitute an opening / closing mechanism capable of opening and closing the water inlet 12 and the water outlet 13.
Here, the water inlet opening / closing valve 15 and the drain opening / closing valve 16 are interlocked with each other, and the other one is opened by opening one of the valves (for example, the water inlet opening / closing valve 15). It is recommended that the other valve be closed by operation. In the case of interlocking, the other (for example, the drain opening / closing valve 16) may be housed in the system housing 1.

  In addition, a phase difference is given to the interlock, and when the valve opening operation is performed, the water inlet 12 is opened and then the drain port 13 is opened. When the valve is closed, the water inlet 13 is closed and then the water inlet 12 is closed. It is good to. The start timing of pouring pure water injected from the water inlet 12 is set earlier than the timing of starting drainage of pure water discharged from the drain port 13, and the end timing of pouring pure water injected from the water inlet 12 is set from the drain port 13. It is set later than the timing of draining the pure water to be discharged. In other words, the drainage start timing is set later than the water injection start timing, and the drainage end timing is set earlier than the water injection end timing.

The opening end of the water inlet 12 is closed by a removable dust cap 17.
The drain port 13 and the overflow port 14 are only required to be able to drain into sewage and the like, and by using appropriate piping, the opening end is not necessarily exposed on the side surface of the system housing 1 as shown in FIG. There is no need to let them.

FIG. 3 shows a method for replacing pure water.
The pure water for replacement is put in a container 21 such as a plastic bottle and provided to the user. The capacity of the replacement pure water container 21 is set to be larger than the capacity of the pure water tank 7, and the amount of pure water stored in the pure water tank 7 (capacity up to the overflow line) is W. The container 21 contains pure water in an amount of W + α.

In addition, the cross-sectional area A1 orthogonal to the height direction of the container 21 is set smaller than the cross-sectional area A2 in the direction orthogonal to the height direction of the pure water tank 7, whereby the height (water head) of the container 21 is set. Is secured.
Further, the container 21 is provided with a flexible water injection pipe 22 that extends from the container body in a pipe shape and has a tip that forms a spout. The open end of the water injection pipe 22 is closed by a cap (not shown), but can be connected to the water injection port 12 with one touch by removing the cap. In addition, the diameter (channel cross-sectional area) of the water injection pipe 22 is the same as or larger than the water injection port 12.

When the pure water in the pure water tank 1 is replaced, the dustproof cap 17 of the inlet 12 of the pure water tank 7 is removed. Then, the cap (not shown) of the water injection pipe 22 of the replacement pure water container 21 is removed, and the water injection pipe 22 of the replacement pure water container 21 is connected to the water injection port 12 of the pure water tank 7.
At this time, the replacement pure water container 21 is placed on the upper surface 1 a of the system housing 1 in order to hold the replacement pure water container 21 higher than the pure water tank 7. Therefore, in the present embodiment, the upper surface 1 a of the system housing 1 is a holding unit that can hold the replacement pure water container 21 connected to the inlet 12 of the pure water tank 7 at a higher level than the pure water tank 7. Equivalent to. Thereby, about the container 21 of the pure water for replacement | exchange, the head height h1 to the water injection port 12 is fully ensured (compared with the water head height h2 to the drain port 13 about the pure water tank 7).

In addition, as a holding part provided in the system housing | casing 1, besides the upper surface 1a of the system housing | casing 1, you may provide a stand etc. in a side part, and an appropriate latching | locking part (hanging hook etc.) You may make it provide.
Next, the opening / closing valve 15 of the inlet 12 is opened and the opening / closing valve 16 of the drain 13 is opened. When performing manual operation separately, after opening the on-off valve 15 of the inlet 12, the on-off valve 16 of the drain port 13 is opened. When interlocking, the opening / closing valve 16 of the drain port 13 is opened at the same time or with a phase delay in opening the opening / closing valve 15 of the water injection port 12.

When the on-off valves 15 and 16 are opened, new pure water in the replacement pure water container 21 is injected into the upper part of the pure water tank 7 from the injection port 12, while old pure water in the pure water tank 7 is injected. And is discharged from the discharge port 13 at the bottom. Thereby, replacement is performed.
Here, regarding the water injection flow rate Q1 from the water injection port 12 and the water discharge flow rate Q2 from the water discharge port 13,
Q1 = a1 × √ (2 g · h1)
Q2 = a2 × √ (2 g · h2)
It becomes.

Therefore, the channel cross-sectional area a1 of the water injection port 12 is set larger than the channel cross-sectional area a2 of the drain port 13 (a1> a2), the container 21 is held higher than the pure water tank 7, and the water head on the container 21 side is set. By ensuring the height h1 sufficiently (so that the relationship of h1> h2 can be maintained even if the liquid level in the container 21 decreases), Q1> Q2.
In this way, the flow rate Q1 of pure water injected from the injection port 12 is made larger than the drainage flow rate Q2 of pure water discharged from the drain port 13.

As a result, the water injection flow rate is higher than the pure water drainage flow rate, so that the liquid level in the pure water tank 7 does not drop during the replacement of pure water, and there is a shortage of pure water. There will be no hindrance.
In addition, excessive pure water is supplied into the pure water tank 7, but when the liquid level in the pure water tank 7 rises and exceeds a predetermined overflow line, the excess pure water flows into the overflow port 14. Overflow from. Therefore, the maximum amount of pure water stored in the pure water tank 7 can be limited to the overflow line.

What is necessary is just to collect | recover and discard the water discharged | emitted from the drain port 13 and the overflow port 14 with the appropriate drainage equipment 23 containing sewage etc.
Thereafter, when pure water in the replacement pure water container 21 is consumed, the opening / closing valve 15 of the inlet 12 is closed and the opening / closing valve 16 of the drain outlet 13 is closed. When performing manual operation separately, after closing the on-off valve 16 of the drain port 13, the on-off valve 15 of the water injection port 12 is closed. In the case of interlocking, the opening / closing valve 15 of the water injection port 12 is closed at the same time or with a phase delay in closing the opening / closing valve 16 of the drain port 13.

Thereafter, the water injection pipe 22 of the container 21 for replacement pure water is removed from the water injection port 12 of the pure water tank 7, the dustproof cap 17 is attached to the water injection port 12, and the series of pure water replacement operations is completed.
According to this embodiment, the water injection port 12 through which pure water can be injected from the outside of the system housing 1 of the fuel cell system into the upper portion of the pure water tank 7 in the housing 1, and pure water from the bottom of the pure water tank 7. In other words, by having a drainage outlet 13 that can be discharged and an opening / closing mechanism (open / close valves 15 and 16) that can be operated from outside the system housing 1 and that can open and close the water injection port 12 and the drainage port 13. The replacement pure water is injected from the water injection port 12 through which pure water can be injected from the outside of the system housing 1 to the top of the pure water tank 7 in the housing 1, and at the same time as the injection, the bottom of the pure water tank 7 is injected. The pure water can be easily replaced from the outside of the system housing 1 during the operation of the fuel cell by discharging the pure water from the drain port 13 and replacing the pure water in the pure water tank 7. Therefore, it is possible to replace the user regardless of the maintenance staff, and the maintenance cost can be greatly reduced. Further, it is possible to reduce expensive ion exchange resins.

  In addition, according to the present embodiment, the configuration further includes the overflow port 14 that causes the pure water to overflow when the liquid level in the pure water tank 7 exceeds a predetermined overflow line. The pure water that is excessively injected into the tank 7 overflows from the overflow port 14 of the pure water tank 7 to allow for safety, and even if the amount of water injection is increased, the pure water is excessively purified in the pure water tank 7. Water can be prevented from being injected.

  Further, according to the present embodiment, the replacement pure water container 21 connected to the water injection port 12 is further configured to have a holding portion that can be held higher than the pure water tank 7, in other words, replacement. The pure water container 21 is connected to the water inlet 12 of the pure water tank 7, the container 21 is held higher than the pure water tank 7, and pure water in the container 21 is poured into the pure water tank 7. The replacement of water can be made more reliable.

In addition, according to the present embodiment, the flow passage cross-sectional area of the water injection port 12 is made larger than the flow passage cross-sectional area of the drain port 13, so that the water injection flow rate is larger than the water discharge flow rate and the pure water during operation is replaced It can be surely performed without any trouble.
Further, according to the present embodiment, the opening / closing mechanism includes the water inlet opening / closing valve 15 for opening / closing the water inlet 12 and the drain opening / closing valve 16 for opening / closing the water outlet 13. Thus, water injection and drainage can be managed reliably.

Further, according to the present embodiment, the water inlet opening / closing valve 15 and the drain opening / closing valve 16 are configured to be linked to each other, thereby facilitating the operation and preventing an erroneous operation including forgetting the operation as much as possible. it can.
Moreover, according to this embodiment, the capacity | capacitance of the container 21 of the pure water for replacement | exchange is made larger than the capacity | capacitance of the pure water tank 7, and the pure water in the pure water tank 7 is replaced more reliably, Purity can be further improved.

Moreover, according to this embodiment, the pure water injection flow rate Q1 injected from the water injection port 12 is set to be larger than the pure water drainage flow rate Q2 discharged from the drain port 13, thereby replacing the pure water during operation. Can be performed more reliably and without problems.
In addition, according to the present embodiment, by setting the water injection start timing of pure water injected from the water injection port 12 earlier than the drain water start timing of pure water discharged from the drain port, excessive discharge is prevented, Replacement of pure water during operation can be performed more reliably and without problems.

In addition, according to the present embodiment, excessive discharge is prevented by setting the end timing of pouring pure water injected from the water inlet 12 later than the end timing of draining pure water discharged from the drain port 13. In addition, replacement of pure water during operation can be performed more reliably and without any trouble.
Next, another embodiment of the present invention will be described with reference to FIGS.
4 and 5, the system housing 1 is provided with a window 19 that is covered by an openable / closable lid member (opening / closing door) 18. The lid member (opening / closing door) 18 can be opened and closed by a hinge or the like.

The water injection port 12 is configured such that the other end of a pipe having one end communicating with the upper part of the pure water tank 7 in the system housing 1 is horizontally or downwardly directed toward the window portion 19 of the system housing 1. Accordingly, the water inlet 12 is arranged in the system housing 1, but is configured to be able to inject pure water from the outside of the system housing 1 through the window portion 19 into the upper portion of the pure water tank 7 in the housing 1. ing.
Although the water inlet opening / closing valve 15 is also arranged in the system housing 1, it can be operated from the outside of the system housing 1 through the window 19 and can open and close the water inlet 12.

The drain opening / closing valve 16 is arranged in the system casing 1 on the premise of interlocking with the water injection opening / closing valve 15.
Therefore, when the pure water in the pure water tank 7 is replaced, the lid member (opening / closing door) 18 is opened, the container 21 is connected to the water inlet 12 and the opening / closing valve 15 is operated through the window 19. Thus, as in the embodiment of FIGS. 2 and 3, pure water can be replaced.

In particular, according to the present embodiment, the system housing 1 has the window portion 19 covered by the lid member 18 that can be opened and closed, and the water inlet 12 is exposed to the outside of the system housing 1 through the window portion 19. By doing so, it is possible to prevent the pure water injection port 12 from being directly exposed to wind and rain on a daily basis, thereby facilitating maintenance.
The drain port 13 and the overflow port 14 do not need to expose the open end on the side surface of the system housing 1 by using appropriate piping as long as drainage to sewage is possible. As an embodiment, the container is connected to the water inlet on the pure water tank side by setting a container for pure water for replacement into the system housing, and the water inlet opening / closing valve is connected with the weight of pure water in the container. It opens automatically and water injection starts, and the drain opening / closing valve opens in conjunction with the water inlet opening / closing valve, draining starts, and when pure water in the container runs out, water injection and draining automatically end It is possible to do so. If it does in this way, a user can replace pure water very simply.

  Although several embodiments of the present invention have been described above with reference to the drawings, the illustrated embodiments are merely illustrative of the present invention, and the present invention is directly illustrated by the described embodiments. It goes without saying that various modifications and changes made by those skilled in the art are included within the scope of the claims.

1 System housing 2 Hydrogen production equipment (reformer)
DESCRIPTION OF SYMBOLS 3 Fuel cell stack 4 Power conditioner 5 Heat exchanger 6 Combustor 7 Pure water tank 8 Pump 9 Condenser 10 Pump 11 Cooler 12 Inlet 13 Outlet 14 Overflow port 15 Inlet opening / closing valve 16 Outlet opening / closing valve 17 Dust prevention cap 18 Lid member (open / close door)
19 Window portion 21 Replacement pure water container 22 Water injection pipe 23 Drainage equipment

Claims (12)

A fuel cell system comprising a pure water tank that stores and circulates pure water in a system housing,
A water injection port capable of injecting pure water into the upper part of the pure water tank in the housing from outside the system housing;
A drainage outlet capable of discharging pure water from the bottom of the pure water tank;
An open / close mechanism that can be operated from outside the system housing and can open and close the water injection port and the drain port;
I have a,
The opening / closing mechanism includes a water inlet opening / closing valve that opens and closes the water inlet, and a drain opening / closing valve that opens and closes the water outlet.
The water inlet opening / closing valve and the water outlet opening / closing valve are interlocked with each other and have a phase difference in connection with each other. The fuel cell system is characterized in that when the valve is opened, the drain opening / closing valve is closed and then the water injection opening / closing valve is closed .   2. The fuel cell system according to claim 1, further comprising an overflow port through which pure water overflows when a liquid level in the pure water tank exceeds a predetermined overflow line.   3. The fuel cell system according to claim 1, further comprising a holding unit capable of holding a replacement pure water container connected to the water injection port at a higher position than the pure water tank. 4. The fuel cell system according to claim 3, wherein the holding unit is a mounting unit on an upper surface of the system casing. The fuel cell system according to any one of claims 1 to 4 , wherein a channel cross-sectional area of the water injection port is larger than a channel cross-sectional area of the drain port. The system housing has a window portion covered with an openable / closable lid member,
The fuel cell system according to any one of claims 1 to 5 , wherein the water injection port is exposed to the outside of the system casing through the window portion. In a fuel cell system including a pure water tank that stores and circulates pure water in a system housing, a pure water replacement method for replacing pure water in the pure water tank,
Inject pure water for replacement from the water injection port that can inject pure water from the outside of the system housing to the top of the pure water tank in the housing.
In conjunction with the injection, the pure water is discharged from the drain outlet at the bottom of the pure water tank, and the pure water in the pure water tank is replaced ,
The timing for starting the injection of pure water injected from the water inlet is set earlier than the timing for starting the drain of pure water discharged from the drain.
A pure water replacement method for a fuel cell system, characterized in that a timing for ending the injection of pure water injected from the water injection port is set later than a timing for ending drainage of pure water discharged from the drain port . 8. The pure water replacement method for a fuel cell system according to claim 7 , wherein the pure water excessively injected into the pure water tank is caused to overflow from an overflow port of the pure water tank. A container for pure water for replacement is connected to the water injection port of the pure water tank, and the container is held higher than the pure water tank, and pure water in the container is injected. The method for replacing pure water in a fuel cell system according to claim 7 or 8 . The pure water replacement method for a fuel cell system according to claim 9, wherein the replacement pure water container is placed on an upper surface of the system casing. The pure water replacement method for a fuel cell system according to claim 9 or 10 , wherein a capacity of the container for pure water for replacement is larger than a capacity of the pure water tank. The flow rate of pure water injected from the water injection port is set to be larger than the flow rate of pure water discharged from the drain port, 12. The method according to any one of claims 7 to 11, How to replace pure water in a fuel cell system.

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