JP6864275B2 - Fuel cell system - Google Patents

Description

The present invention relates to a fuel cell system that produces hot water using waste heat of a fuel cell.

Conventionally, a heating device (2) disclosed in Patent Document 1 below is known. This heating device (2) recovers the waste heat of the generator (4) provided with the fuel cell (60) and the off-gas (exhaust gas) of the generator (4) and collects the waste heat of the second heat exchanger (14). The cooling water circulation path (34) supplied to the first heat exchanger (12), the heat storage tank (16) for storing hot water supply water inside, and the hot water supply water in the heat storage tank (16) are used in each of the heat exchangers (16). From the hot water supply water circulation channel (8) that circulates and heats between 12 and 14), the water supply channel (39) that supplies tap water as hot water supply to the heat storage tank (16), and the heat storage tank (16). It is provided with a hot water outlet (heat storage tank outlet 44, first hot water supply channel 46, second hot water supply channel 54, etc.) and an auxiliary heat source machine (51) provided in the hot water outlet to heat hot water for hot water supply by burning gas.

Japanese Unexamined Patent Publication No. 2015-165176 (paragraphs [0019]-[0035], FIG. 1)

However, in the prior art, tap water is used as hot water for hot water supply from the water supply channel (39). Therefore, a scale (a hardness component in water bonded to carbonate ions, silica, etc. and precipitated) is attached to a heating device (auxiliary heat source machine 51) provided in a hot water outlet from the hot water storage tank (heat storage tank 16). It may cause troubles such as heat transfer inhibition and flow path blockage.

Further, such a scale trouble may occur not only in the heating device but also in the circulation pump of the circulation path and the heat exchanger for recovering the waste heat of the fuel cell as described below.

That is, first, a circulation path passing through the vicinity of the use point (the hot water extraction section to the use point) is provided so that hot water can be immediately discharged at the use point of hot water, and water is supplied to the circulation path from the hot water storage tank. You may want to use hot water. In this case as well, if the water supplied to the hot water storage tank is tap water, the scale may adhere to the circulation pump provided in the circulation path, causing trouble.

Further, in the heat exchanger for recovering waste heat of the fuel cell, when the off gas of the fuel cell and the water flowing from the hot water storage tank are exchanged for heat, local boiling may occur in the heat exchanger due to the high temperature of the off gas. , May cause scale trouble. This is not limited to the case where the stored water itself in the hot water storage tank is circulated to the heat exchanger for waste heat recovery (that is, the heat exchanger with off-gas), and the stored water in the hot water storage tank is as in the prior art. It may also occur when the heat exchange between (water in the hot water supply circulation path 8) and the off-gas of the fuel cell is performed via the circulation circuit (cooling water circulation path 34). That is, an off-gas heat exchanger that exchanges heat between the off-gas of the fuel cell and its cooling water, and a heating heat exchanger that heats the stored water in the hot water storage tank with the cooling water heated by this off-gas heat exchanger (first). Even when a circulation circuit (cooling water circulation path 34) for circulating cooling water between the heat exchanger 12 and the second heat exchanger 14) is provided, when the circulating cooling water is tap water, an off-gas heat exchanger in particular. There is a risk of causing trouble by attaching scale to the heat.

Therefore, an object to be solved by the present invention is to prevent scale from adhering to a heat exchanger for heating stored water in a hot water storage tank, that is, a heat exchanger for recovering waste heat of a fuel cell. ..

The present invention has been made to solve the above problems, and the invention according to claim 1 is an off-gas heat exchanger that exchanges heat between the off-gas of a fuel cell and its cooling water, and the off-gas heat exchanger. A heating heat exchanger that heats the stored water in the hot water storage tank with heated cooling water, and a circulation circuit that circulates the cooling water between the off-gas heat exchanger and the heating heat exchanger are provided. The fuel cell system is characterized in that soft water from which the hardness component in the water has been removed by a hard water softener using a sodium-type cation exchange resin is used as the cooling water that circulates in the circulation circuit.

According to the invention of claim 1, the off-gas waste heat of the fuel cell is stored in the hot water storage tank via the circulating water of the circulation circuit (circulating water between the off-gas heat exchanger and the heating heat exchanger). Water can be heated. At that time, since soft water is used as the circulating water in the circulation circuit, it is possible to prevent the scale from adhering to the off-gas heat exchanger or the heating heat exchanger.

According to the second aspect of the present invention, the hard water softening device is provided in a water supply channel to the hot water storage tank, and a branch path is provided in the water supply channel on the downstream side of the hard water softening device. The fuel cell system according to claim 1, wherein the fuel cell system is connected to the circulation circuit via a check valve.

According to the fuel cell system of the present invention, it is possible to prevent the scale from adhering to the heat exchanger for heating the stored water in the hot water storage tank, that is, the heat exchanger for recovering the waste heat of the fuel cell.

It is the schematic which shows Example 1 of the fuel cell system of this invention. It is the schematic which shows Example 2 of the fuel cell system of this invention.

Hereinafter, specific examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view showing Example 1 of the fuel cell system of the present invention.
The fuel cell system 1 of the present embodiment uses a circulation path 3 that circulates hot water and has a hot water extraction unit 2 to a use point, stores water supply to the circulation path 3, and uses waste heat of the fuel cell 4. A hot water storage tank 5 in which the stored water is heated and a hard water softening device 7 provided in the water supply channel 6 to the hot water storage tank 5 are provided.

The circulation path 3 is a flow path for circulating hot water by the circulation pump 8. The circulation path 3 is provided with a hot water take-out unit 2 to a use point. When the circulation pump 8 is operated, the hot water discharged from the discharge port of the circulation pump 8 is returned to the suction port of the circulation pump 8 via the circulation path 3. In addition, hot water can be taken out from one or more hot water take-out portions 2 provided in the middle of the circulation path 3 to various use points via appropriate pipes if desired. That is, when the hot water outlet of the use point is opened, hot water can be discharged to the outside from the hot water outlet.

The point of use of hot water is not particularly limited, but for example, in the case of a fuel cell system 1 for home use, it may be a curan, a shower or a bathtub, and in the case of a fuel cell system 1 for business use, various hot water utilization devices (for example, in a kitchen). It is said to be the hot spring part).

The circulation pump 8 typically continues to operate at all times. However, in some cases, the circulation pump 8 may operate by detecting the hot water discharge (for example, detecting the pressure drop in the circulation path 3 due to the hot water discharge) when the hot water extraction unit 2 discharges hot water.

A heating device 9 is provided in the circulation path 3 in order to heat the circulating water in the circulation path 3. The structure of the heating device 9 is not particularly limited, but is composed of, for example, a burner, an electric heater, or a steam heater. In this embodiment, the heating device 9 operates while the circulation pump 8 is operating (that is, circulating water is circulating in the circulation path 3). Further, the heating device 9 is controlled so as to maintain the outlet side water temperature at a set temperature. As a result, the hot water take-out unit 2 can take out hot water at a set temperature.

The hot water channel 10 from the hot water storage tank 5 is connected to the circulation path 3, but the heating device 9 is located downstream of the connection portion with the hot water channel 10 in the circulation path 3 and from the hot water extraction section 2. It is preferably provided upstream. In the illustrated example, the heating device 9 is provided in the hot water feeding path 3a from the circulation pump 8 to the hot water extraction unit 2. However, depending on the case, the heating device 9 may be provided in the hot water return path 3b from the hot water extraction unit 2 to the circulation pump 8.

The circulation path 3 is preferably further provided with an expansion tank (not shown). As is well known, the expansion tank is a device that absorbs the volume change of the circulating water in the circulation path 3, and may be an open type that opens the circulating water to the atmosphere, or absorbs the volume change of the circulating water without opening the circulating water to the atmosphere. It may be a closed type with a built-in mechanism. By providing the expansion tank in the circulation path 3, the expansion tank can absorb the volume change due to the temperature change of the circulating water.

The hot water storage tank 5 stores water supply to the circulation path 3. The stored water in the hot water storage tank 5 is heated by using the waste heat of the fuel cell 4. In this embodiment, the hot water storage tank 5 is a closed tank (that is, a tank that is not open to the atmosphere).

A water supply channel 6 and a hot water channel 10 are connected to the hot water storage tank 5. It is preferable that the water supply channel 6 is connected to the lower part of the hot water storage tank 5 and the hot water channel 10 is connected to the upper part of the hot water storage tank 5. Then, the hot water channel 10 from the hot water storage tank 5 is connected to the circulation path 3. At that time, it is preferable that the hot water channel 10 is connected to the circulation path 3 downstream of the hot water extraction unit 2 and upstream of the heating device 9.

A hard water softening device 7 is provided in the water supply channel 6 to the hot water storage tank 5. As is well known, the hard water softening device 7 is a device that removes hardness components (calcium ions and magnesium ions) in water using a cation exchange resin or the like. The cation exchange resin adsorbing the hardness component is regenerated by passing a regenerating agent (for example, an aqueous sodium chloride solution) before the removal ability is lost. Further, in the water supply channel 6 to the hot water storage tank 5, a water supply pump (not shown) is provided on the inlet side or the outlet side of the hard water softening device 7. By operating the water supply pump, water can be supplied to the hot water storage tank 5 and thus to the circulation path 3.

As described above, in this embodiment, the hot water storage tank 5 is a closed type tank. In this case, the inside of the hot water storage tank 5 is filled with water, and by operating the water supply pump, the hot water can be supplied from the hot water storage tank 5 to the hot water channel 10 and the water for the hot water can be supplied from the water supply channel 6 to the hot water storage tank 5. .. That is, when hot water is discharged from the hot water storage tank 5 to the circulation path 3 due to the hot water outlet portion 2 of the circulation path 3, the amount of water corresponding to the hot water discharge is supplied from the water supply channel 6 to the hot water storage tank 5. To. Therefore, the water supply pump may be always operated. Even in that case, the actual water supply from the water supply channel 6 to the hot water storage tank 5 is not performed unless the hot water is discharged from the hot water storage tank 5 to the circulation path 3.

However, in some cases, the water supply pump may be controlled to operate only when water supply to the hot water storage tank 5 is required. For example, the water supply pump may be on / off controlled or inverter controlled so as to maintain the pressure on the secondary side (outlet side, that is, the hot water storage tank 5 side) at a predetermined pressure. In this case, when the hot water extraction unit 2 starts to discharge hot water, the pressure in the hot water storage tank 5 drops, and this is detected to operate the water supply pump. Then, when the hot water outlet at the hot water extraction unit 2 is stopped, the pressure on the secondary side of the water supply pump increases, so that it is detected and the water supply pump is stopped.

The fuel cell 4 includes a fuel cell main body 11, and the fuel cell main body 11 includes a reformer, a cell stack, and the like (not shown). Raw fuel (city gas) G, air A, and water (reformed water) W are supplied to the fuel cell main body 11. Then, as is well known, hydrogen is generated by steam reforming reaction of raw fuel (city gas containing methane gas as a main component) and water (steam) in a reformer, and the hydrogen and oxygen in the air are converted. A chemical reaction is carried out in the cell stack to generate electricity. The generated electricity is converted into alternating current by an inverter and supplied to various electric devices. The type of the fuel cell 4 is not particularly limited. In this embodiment, the solid oxide fuel cell (SOFC) is used, but for example, the solid polymer electrolyte cell (PEFC) may be used.

The waste heat of the fuel cell 4 is used to heat the stored water in the hot water storage tank 5. Typically, the off-gas waste heat of the fuel cell 4 is used to heat the stored water in the hot water storage tank 5. That is, during power generation in the fuel cell 4, off-gas (exhaust gas) is discharged from the cell stack and the reformer, and the off-gas waste heat is used to heat the stored water in the hot water storage tank 5. Alternatively, or in addition to this, in the cooler of the cell stack, the waste heat from the cell stack is recovered to heat the stored water in the hot water storage tank 5.

In order to heat the stored water in the hot water storage tank 5 with the off-gas waste heat of the fuel cell 4, in this embodiment, the off-gas heat exchanger 12 of the fuel cell 4 and the heating heat exchanger 13 of the hot water storage tank 5 are used. It is connected by a circulation circuit 14.

The off-gas heat exchanger 12 exchanges heat without mixing the off-gas from the fuel cell main body 11 with the cooling water thereof. Therefore, the off-gas is passed through the off-gas heat exchanger 12 from the fuel cell main body 11 via the off-gas passage 15, and the circulating water of the circulation circuit 14 is passed as the off-gas cooling water. As a result, in the off-gas heat exchanger 12, the off-gas is cooled by the circulating cooling water, and the moisture in the off-gas is condensed. On the other hand, the circulating cooling water of the circulation circuit 14 is heated by exchanging heat with the off-gas in the off-gas heat exchanger 12.

A separator 16 is provided on the outlet side of the off-gas from the off-gas heat exchanger 12, so that the off-gas gas and liquid can be separated through the off-gas heat exchanger 12. Then, the gas is discharged to the outside, and the condensed water can be resupplied to the fuel cell main body 11 via the supply pump 17 as water supply to the fuel cell main body 11.

The heating heat exchanger 13 is arranged in the hot water storage tank 5 in the illustrated example, and exchanges heat without mixing the stored water in the hot water storage tank 5 and the circulating cooling water from the off-gas heat exchanger 12. As a result, in the heating heat exchanger 13, the stored water in the hot water storage tank 5 is heated, while the circulating cooling water in the circulation circuit 14 is cooled.

The circulation circuit 14 circulates water between the off-gas heat exchanger 12 and the heating heat exchanger 13. Specifically, cooling water is supplied from the heating heat exchanger 13 to the off-gas heat exchanger 12 via the cooling water feed path 14a, and cooling is performed from the off-gas heat exchanger 12 to the heating heat exchanger 13. The cooling water is returned through the water return path 14b. Then, by operating the circulation pump 18 provided in the cooling water feed path 14a (or the cooling water return path 14b), the cooling water is circulated between the heating heat exchanger 13 and the off-gas heat exchanger 12. Can be done. As described above, the off-gas heat exchanger 12 is a heat exchanger between the off-gas of the fuel cell 4 and the circulating cooling water of the circulation circuit 14, and the heating heat exchanger 13 is the circulating cooling water of the circulation circuit 14. It is a heat exchanger with the stored water in the hot water storage tank 5.

In this embodiment, the radiator 19 and the circulation pump 18 are provided in order from the heating heat exchanger 13 to the off-gas heat exchanger 12 in the cooling water feed path 14a. Although the circulation pump 18 is provided in the cooling water feed path 14a in this embodiment, it may be provided in the cooling water return path 14b as the case may be.

The radiator 19 includes a cooling fan 20, and by operating the cooling fan 20 at a desired time, the cooling water supplied to the off-gas heat exchanger 12 can be air-cooled. This is to realize so-called water independence in the fuel cell 4.

That is, in order to cool the off-gas below the dew point temperature in the off-gas heat exchanger 12, condense the water in the off-gas, and resupply the condensed water to the reformer (that is, water self-sustaining), the off-gas heat exchanger It is necessary to prevent the temperature of the water supplied to 12 from becoming too high. Therefore, in this embodiment, it is preferable to provide a radiator 19 to maintain the temperature of the circulating cooling water supplied to the off-gas heat exchanger 12 to be equal to or lower than the first target temperature. Specifically, in the cooling water feed path 14a, a first temperature sensor 21 is provided on the outlet side of the radiator 19, and the radiator 19 is provided so as to maintain the detected temperature at the first target temperature (for example, 40 ° C.). Adjust the ventilation volume. Here, the ventilation amount of the radiator 19 is adjusted by controlling the drive frequency and the rotation speed of the motor of the cooling fan 20 with an inverter. In this way, when the circulating cooling water in the circulation circuit 14 is overheated (when the water temperature to the off-gas heat exchanger 12 is equal to or higher than a predetermined value), the cooling fan 20 of the radiator 19 is operated to adjust the water temperature of the cooling water. By lowering it, the water self-reliance of the fuel cell 4 can be surely achieved.

Further, the circulation circuit 14 is provided with a circulation flow rate adjusting means for circulating cooling water. In this embodiment, as a circulation flow rate adjusting means, a flow rate adjusting valve 22 is provided in the cooling water return path 14b from the off-gas heat exchanger 12 to the heating heat exchanger 13. By adjusting the opening degree of the flow rate adjusting valve 22 while the circulation pump 18 is operating, the circulation flow rate in the circulation circuit 14 can be adjusted. In this embodiment, the flow rate adjusting valve 22 is provided in the cooling water return path 14b from the off-gas heat exchanger 12 to the heating heat exchanger 13, but in some cases, the off-gas heat exchange from the heating heat exchanger 13 It may be provided in the cooling water feeding path 14a to the vessel 12. Further, the circulation flow rate adjusting means may be composed of an inverter for changing the drive frequency of the circulation pump 18 and thus the rotation speed. That is, the circulation pump 18 may be controlled by the inverter to adjust the circulation flow rate in the circulation circuit 14.

In order to stably heat the stored water in the hot water storage tank 5 by the heating heat exchanger 13, it is preferable to maintain the temperature of the circulating cooling water supplied to the heating heat exchanger 13 at the second target temperature. Specifically, a second temperature sensor 23 is provided in the cooling water return path 14b, and the opening degree of the flow rate adjusting valve 22 is adjusted so as to maintain the detected temperature at the second target temperature (even 60 to 75 ° C.). It is preferable to adjust the circulation flow rate of the circulation circuit 14. Even when the circulation flow rate adjusting means is provided in the cooling water feed path 14a, the second temperature sensor 23 is provided in the cooling water return path 14b and is controlled so as to maintain the temperature of the water supplied to the heating heat exchanger 13 as desired. Will be done.

By the way, as the circulating water of the circulation circuit 14, in this embodiment, the soft water from the hard water softening device 7 is used. Therefore, a branch path 24 from the water supply channel 6 is connected to the circulation circuit 14. Specifically, the water supply channel 6 is provided with a branch path 24 branched downstream from the hard water softening device 7, and the tip of the branch path 24 is connected to the circulation circuit 14. It is preferable that the check valve 25 is provided in the branch path 24. Basically, the circulation circuit 14 is filled with soft water from the hard water softening device 7 in advance, and the reduced amount due to evaporation or the like is replenished from the branch path 24. The connection position of the branch path 24 with respect to the circulation circuit 14 is not particularly limited, but in the illustrated example, it is connected to the inlet side of the circulation pump 18.

Next, the control (operation method) of the fuel cell system 1 of this embodiment will be described. The series of controls described below are automatically performed using a controller (not shown).

Along with the operation of the fuel cell 4, the fuel cell system 1 is operated. As a result, the circulation pump 18 of the circulation circuit 14 operates, and the circulation pump 8 of the circulation path 3 operates.

By operating the circulation pump 18, cooling water is circulated between the off-gas heat exchanger 12 of the fuel cell 4 and the heating heat exchanger 13 of the hot water storage tank 5. As a result, the off-gas from the fuel cell main body 11 is cooled in the off-gas heat exchanger 12, while the stored water in the hot water storage tank 5 is heated in the heating heat exchanger 13. At this time, in order to realize water independence in the fuel cell 4, the motor of the cooling fan 20 of the radiator 19 is inverter-controlled so as to maintain the detection temperature of the first temperature sensor 21 at the first target temperature. Further, in order to stably heat the stored water in the hot water storage tank 5, the opening degree of the flow rate adjusting valve 22 is controlled so as to maintain the detection temperature of the second temperature sensor 23 at the second target temperature.

Hot water is circulated in the circulation path 3 by the operation of the circulation pump 8, and at this time, the heating device 9 is controlled to maintain the outlet side water temperature at the target temperature. Therefore, hot water having a target temperature is supplied to the hot water take-out unit 2, and the hot water can be discharged from the hot water take-out unit 2 to the use point if desired. Along with the hot water discharged from the hot water extraction unit 2, a corresponding amount of water is replenished from the hot water storage tank 5 to the circulation channel 3, and the hot water storage tank 5 is replenished with water from the water supply channel 6.

According to the fuel cell system 1 of the present embodiment, soft water is used as water supply to the hot water storage tank 5 and the circulation path 3, so that the circulation pump 8 and the heating device 9 (for example, when the heating device 9 is a burner) of the circulation path 3 are used. The scale is prevented from adhering to the heat exchanger 13 for heating the hot water storage tank 5 in addition to the heat exchanger between the combustion gas and the water flowing through the circulation path 3. Further, since soft water is also used for the circulating water of the circulation circuit 14, it is possible to prevent the scale from adhering to the circulation pump 18 of the circulation circuit 14, the off-gas heat exchanger 12, the heating heat exchanger 13, and the like. .. In particular, it is possible to prevent scale from adhering to the off-gas heat exchanger 12, which may cause local boiling, and prevent troubles due to poor water flow and poor heat transfer.

The hard water softening device 7 requires electric power to drive a flow path switching valve (valve mechanism for switching processes such as liquid passage, extrusion, and rinsing of a regenerating agent) at a regeneration timing of a cation exchange resin or the like. .. Therefore, the hard water softening device 7 is preferably driven by the electric power generated by the fuel cell 4. This applies not only to the hard water softening device 7, but also to, for example, the circulation pump 8 and the circulation pump 18. In any case, it is not necessary to prepare a separate power source by operating the fuel cell 4. Further, by using the electric power generated by the fuel cell 4 using inexpensive city gas instead of the commercial power source, the operation can be performed at low cost.

FIG. 2 is a schematic view showing Example 2 of the fuel cell system of the present invention. The fuel cell system 1 of the second embodiment is basically the same as that of the first embodiment. Therefore, in the following, the differences between the two will be mainly described, and the corresponding parts will be described with the same reference numerals.

In the first embodiment, the hot water from the hot water storage tank 5 can be discharged to the outside through the circulation path 3, but in the second embodiment, the circulation path 3 is not provided. That is, the hot water channel 10 from the hot water storage tank 5 is directly connected to the use point (that is, in a one-way state). Then, a heating device 9 is provided in the hot water channel 10. With the heating device 9, the temperature at which the hot water is discharged to the use point can be maintained as desired. Since other configurations and controls are the same as those in the first embodiment, the description thereof will be omitted.

The fuel cell system 1 of the present invention is not limited to the configuration (including control) of each of the above-described embodiments, and can be appropriately changed. In particular, the hot water storage tank 5 in which the stored water is heated by using the waste heat of the fuel cell 4, the hard water softening device 7 provided in the water supply channel 6 to the hot water storage tank 5, and the water from the hot water storage tank 5 to the use point. If it is provided with a heating device 9 for heating the above, other configurations can be appropriately changed.

For example, in each of the above embodiments, a heating heat exchanger 13 is installed in the hot water storage tank 5 to indirectly exchange heat between the circulating water in the circulation circuit 14 and the stored water in the hot water storage tank 5, but in some cases, heating is performed. The installation of the heat exchanger 13 may be omitted, and the stored water itself in the hot water storage tank 5 may be circulated with the off-gas heat exchanger 12. That is, the stored water in the hot water storage tank 5 is supplied to the off-gas heat exchanger 12 via the cooling water feed path 14a, heated by the off-gas heat exchanger 12 using the off-gas waste heat, and the cooling water return path 14b is provided. The circulation of returning to the hot water storage tank 5 via the hot water storage tank 5 may be repeated. Alternatively, in some cases, a heating heat exchanger 13 is installed outside the hot water storage tank 5, the stored water in the hot water storage tank 5 is circulated through the heating heat exchanger 13, and the circulating water and the circulation circuit 14 are circulated and cooled. Indirect heat exchange with water may be performed.

Further, in each of the above embodiments, the water supply to the hot water storage tank 5 is controlled by the water supply pump provided in the water supply channel 6, but the water supply may be controlled by opening and closing the water supply valve provided in the water supply channel 6. For example, a water supply valve may be provided on the inlet side of the hard water softening device 7 and the water supply to the hot water storage tank 5 may be controlled by opening and closing the valve.

Further, in each of the above embodiments, the hot water storage tank 5 is composed of a closed type tank, but may be composed of an open type tank in some cases. In that case, the water supply from the water supply channel 6 may be controlled so as to maintain the water level in the hot water storage tank 5 at the set water level. For example, the water supply pump provided in the water supply channel 6 may be controlled based on the water level in the hot water storage tank 5. Then, a water supply pump may be provided in the hot water passage 10, and the water supply pump may be operated so as to replenish the water corresponding to the hot water when the hot water extraction unit 2 discharges hot water.

1 Fuel cell system 2 Hot water outlet 3 Circulation path (3a: Hot water feed path, 3b: Hot water return path)
4 Fuel cell 5 Hot water storage tank 6 Water supply channel 7 Hard water softener 8 Circulation pump 9 Heating device 10 Hot water channel 11 Fuel cell body 12 Off-gas heat exchanger 13 Heat exchanger for heating 14 Circulation circuit (14a: Cooling water feed path, 14b: Cooling water return path)
15 Off-gas path 16 Separator 17 Supply pump 18 Circulation pump 19 Radiator 20 Cooling fan 21 First temperature sensor 22 Flow control valve 23 Second temperature sensor 24 Branch path 25 Check valve A Air G Raw fuel W Water

Claims (2)

An off-gas heat exchanger that exchanges heat between the off-gas of a fuel cell and its cooling water,
A heating heat exchanger that heats the stored water in the hot water storage tank with the cooling water heated by this off-gas heat exchanger,
A circulation circuit for circulating cooling water between the off-gas heat exchanger and the heating heat exchanger is provided.
A fuel cell system characterized in that soft water from which the hardness component in water has been removed by a hard water softening device using a sodium-type cation exchange resin is used as the cooling water that circulates in the circulation circuit. The hard water softening device is provided in the water supply channel to the hot water storage tank.
The fuel according to claim 1, wherein a branch path is provided in the water supply channel on the downstream side of the hard water softening device, and the branch path is connected to the circulation circuit via a check valve. Battery system.

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