JP2023085982A - fuel cell system - Google Patents

Abstract

To provide a technique that can reduce the concentration of ammonia included in reformed gas while reducing the amount of heating in a reformer.SOLUTION: A fuel cell system comprises: a reformer that reforms raw material gas to generate reformed gas; a heating part that heats the raw material gas in the reformer; a gas passage through which the reformed gas generated by the reformer passes; a temperature sensor that detects the temperature of the reformed gas passing through the gas passage; a fuel cell that generates electric power using fuel gas generated by removing ammonia from the reformed gas passing through the gas passage; and a control part that controls the amount of heating by the heating part in accordance with the concentration of ammonia included in the reformed gas estimated from a detected temperature from the temperature sensor.SELECTED DRAWING: Figure 1

Description

The technology disclosed herein relates to a fuel cell system.

Patent document 1 discloses a fuel cell system. The fuel cell system of Patent Document 1 includes a reformer that generates a reformed gas (hydrogen-containing gas) by reforming a raw material gas, a combustor that heats the reformer, and a An ammonia remover that removes ammonia contained in the reformed gas, a fuel cell that generates electricity using the reformed gas discharged from the ammonia remover, and a temperature of the reformed gas after ammonia is removed by the ammonia remover. and a temperature detector sensor to detect. The combustor burns the gas discharged from the ammonia remover and the off-gas discharged from the fuel cell to heat the reformer. In the fuel cell system of Patent Document 1, the controller starts supplying the reformed gas from the reformer to the fuel cell when the temperature of the reformed gas detected by the temperature sensor is equal to or higher than a predetermined threshold. .

WO2011/158495

In a fuel cell system, if the concentration of ammonia contained in the reformed gas is high, the power generation efficiency of the fuel cell may decrease. In addition, if the amount of heating in the reformer is large, the energy consumption becomes large, and the efficiency of the whole system may be lowered. Accordingly, the present specification provides a technique capable of suppressing the concentration of ammonia contained in the reformed gas while suppressing the amount of heating in the reformer.

The fuel cell system disclosed in the present specification includes a reformer that reforms a raw material gas to produce a reformed gas, a heating unit that heats the raw material gas in the reformer, and a gas passage through which the generated reformed gas passes; a temperature sensor that detects the temperature of the reformed gas passing through the gas passage; and removing ammonia from the reformed gas that has passed through the gas passage. a fuel cell that generates electricity using the fuel gas generated by the above; and a control unit that controls the amount of heating by the heating unit according to the concentration of ammonia contained in the reformed gas estimated from the temperature detected by the temperature sensor. It has

According to the above configuration, it is possible to suppress the concentration of ammonia contained in the reformed gas while suppressing the heating amount in the reformer. For example, when the concentration of ammonia estimated from the temperature detected by the temperature sensor is high, it is estimated that the decomposition of ammonia is not promoted in the reformer. In this case, the decomposition of ammonia can be promoted by increasing the amount of heating by the heating unit, and the concentration of ammonia contained in the reformed gas can be suppressed. Further, when the concentration of ammonia estimated from the temperature detected by the temperature sensor is low, it is estimated that the decomposition of ammonia is promoted in the reformer. In this case, the amount of heating by the heating unit can be reduced. Since the amount of heating needs to be increased only when the decomposition of ammonia is not promoted, the amount of heating in the reformer can be suppressed.

The fuel cell system may further include a pressure sensor that detects pressure of the reformed gas passing through the gas passage. The control unit may control the amount of heating by the heating unit according to the concentration of ammonia contained in the reformed gas estimated from the temperature detected by the temperature sensor and the pressure detected by the pressure sensor.

According to this configuration, the concentration of ammonia contained in the reformed gas is estimated from the temperature detected by the temperature sensor and the pressure detected by the pressure sensor, thereby improving the estimation accuracy. Thereby, the amount of heating by the heating unit can be controlled with high accuracy.

The control unit may increase the amount of heating by the heating unit when the concentration of ammonia contained in the reformed gas is estimated to be equal to or higher than a predetermined first threshold.

According to this configuration, by increasing the amount of heating when the concentration of ammonia is high, the decomposition of ammonia can be promoted and the concentration of ammonia can be reduced.

The control unit may reduce the amount of heating by the heating unit when the concentration of ammonia contained in the reformed gas is estimated to be less than a predetermined second threshold. The second threshold may be a value less than the first threshold.

According to this configuration, unnecessary heating can be suppressed by reducing the heating amount when the concentration of ammonia is low.

The heating unit may include a first heater that heats the raw material gas by Joule heat. According to this configuration, it is possible to accurately control the amount of heating by the heating unit.

The heating unit may include a second heater that heats the raw material gas with heat of the reformed gas generated by the reformer. According to this configuration, the raw material gas can be heated by effectively utilizing the heat of the reformed gas.

The heating unit may include a third heater that heats the raw material gas with heat of exhaust gas discharged from the fuel cell. According to this configuration, the raw material gas can be heated by effectively utilizing the heat of the exhaust gas from the fuel cell.

The fuel cell system may further include a remover that removes ammonia from the reformed gas that has passed through the gas passage to generate the fuel gas.

According to this configuration, it is possible to supply the fuel cell with good quality fuel gas with a low concentration of ammonia. Further, if the structure can suppress the concentration of ammonia contained in the reformed gas, the amount of ammonia removed by the remover can be suppressed, so the load on the remover can be reduced.

1 is a diagram schematically showing the fuel cell system of Example 1. FIG. 4 is a table showing ammonia concentration relation information of Example 1; 4 is a flowchart of heating amount control processing in the first embodiment; 4 is a time chart of heating amount control processing of the first embodiment; FIG. 4 is a diagram schematically showing a fuel cell system of Example 2; 10 is a flowchart of heating amount control processing according to the second embodiment; The table which shows the ammonia concentration relationship information of a modification.

(Example 1)
A fuel cell system 2 of Example 1 will be described with reference to the drawings. As shown in FIG. 1, the fuel cell system 2 of Example 1 includes a raw material tank 10, a vaporizer 20, a reformer 12, a remover 14, a fuel cell 16, and a controller 50. there is

The raw material tank 10 stores liquid ammonia as a raw material. A liquid supply path 70 through which liquid ammonia flows is connected to the raw material tank 10 . The liquid supply path 70 has an upstream end connected to the raw material tank 10 and a downstream end connected to the vaporizer 20 . Liquid ammonia is supplied from the raw material tank 10 to the vaporizer 20 through the liquid supply path 70 . The liquid supply path 70 is provided with a pump 72 that pressure-feeds the liquid ammonia from the upstream side of the liquid supply path 70 to the downstream side.

The vaporizer 20 heats and vaporizes the liquid ammonia supplied through the liquid supply path 70 . As a result, gaseous ammonia is generated as a raw material gas. The vaporizer 20 is connected to a raw material gas supply path 60 through which raw material gas (gaseous ammonia) flows. The source gas supply path 60 has an upstream end connected to the vaporizer 20 and a downstream end connected to the reformer 12 . The raw material gas is supplied from the vaporizer 20 to the reformer 12 through the raw material gas supply path 60 .

The reformer 12 reforms the raw material gas (gaseous ammonia) supplied through the raw material gas supply path 60 to generate a reformed gas. Catalysts used for reforming the raw material gas are, for example, copper, nickel, ruthenium, and the like. The reformed gas contains hydrogen generated by reforming the raw material gas. In addition, the reformed gas contains undecomposed ammonia. The concentration of ammonia contained in the reformed gas fluctuates depending on the progress of reforming.

The reformer 12 includes a first heater 40 (an example of a heating section) that heats the raw material gas during reforming of the raw material gas. The first heater 40 raises the temperature of the source gas in the reformer 12 . The first heater 40 is, for example, of an electric or gas configuration. The first heater 40 of this embodiment is an electric heater that generates heat when energized. The first heater 40 (electric heater) heats the object to be heated by Joule heat when the power is on, and does not heat the object to be heated when the power is off. The amount of heating by the first heater 40 is controlled by the controller 50 . In a modification, the first heater 40 may be a gas burner that heats an object to be heated by combustion heat of gas.

A reformed gas supply passage 62 (an example of a gas passage) through which the reformed gas flows is connected to the reformer 12 . The reformed gas supply path 62 is connected to the reformer 12 at its upstream end and to the remover 14 at its downstream end. The reformed gas is supplied from the reformer 12 to the remover 14 through the reformed gas supply passage 62 .

A heat exchanger 22 is provided in the reformed gas supply path 62 . A heat exchanger 22 is provided between the reformer 12 and the remover 14 . The heat exchanger 22 cools the reformed gas by exchanging heat between the reformed gas passing through the reformed gas supply passage 62 and an external fluid. The heat exchanger 22 reduces the temperature of the reformed gas supplied from the reformer 12 to the remover 14 . Although the structure of the heat exchanger 22 is not particularly limited, it may include, for example, fins for heat exchange.

A temperature sensor 30 is provided in the reformed gas supply path 62 . A temperature sensor 30 is provided between the reformer 12 and the heat exchanger 22 . A temperature sensor 30 detects the temperature of the reformed gas discharged from the reformer 12 . The temperature sensor 30 detects the temperature of the reformed gas passing through the reformed gas supply passage 62 upstream of the heat exchanger 22 . The temperature sensor 30 detects the temperature of the reformed gas before ammonia is removed by the remover 14 and before heat is exchanged by the heat exchanger 22 . Information on the temperature detected by the temperature sensor 30 is transmitted to the control unit 50 .

A pressure sensor 32 is provided in the reformed gas supply path 62 . A pressure sensor 32 is provided between the reformer 12 and the heat exchanger 22 . A pressure sensor 32 detects the pressure of the reformed gas discharged from the reformer 12 . The pressure sensor 32 detects the pressure of the reformed gas passing through the reformed gas supply passage 62 upstream of the heat exchanger 22 . The pressure sensor 32 detects the pressure of the reformed gas before ammonia is removed by the remover 14 and before heat is exchanged by the heat exchanger 22 . Information on the pressure detected by the pressure sensor 32 is transmitted to the control unit 50 .

The remover 14 removes ammonia from the reformed gas by adsorbing the ammonia contained in the reformed gas supplied through the reformed gas supply path 62 with an adsorbent. As a result, fuel gas with a reduced ammonia concentration is produced. Adsorbents used for adsorption of ammonia are, for example, activated carbon, zeolite, MOF (Metal Organic Framework), and the like. For example, the interior of the container of the remover 14 is filled with an adsorbent.

A fuel gas supply passage 64 through which fuel gas flows is connected to the remover 14 . The fuel gas supply path 64 has an upstream end connected to the remover 14 and a downstream end connected to the fuel cell 16 . Fuel gas is supplied from the remover 14 to the fuel cell 16 through the fuel gas supply passage 64 .

In addition to the fuel gas supply path 64, the fuel cell 16 is connected to an air supply path 68 through which air flows. The air supply path 68 has an upstream end connected to an air supply source (not shown) and a downstream end connected to the fuel cell 16 . Air is supplied from an air supply source to the fuel cell 16 through an air supply passage 68 . Note that the upstream end of the air supply path 68 may be open to the outside air.

The fuel cell 16 generates electricity using the fuel gas supplied through the fuel gas supply path 64 and the air supplied through the air supply path 68 . The fuel cell 16 includes, for example, a plurality of battery cells (not shown) stacked inside a container. Generate electricity. The battery cell is, for example, a solid oxide fuel cell (SOFC) or a polymer electrolyte fuel cell (PEFC), but is not limited to these. In the fuel cell 16 that generates power using fuel gas, unreacted fuel gas is discharged as exhaust gas during power generation.

An exhaust gas passage 66 through which exhaust gas flows is connected to the fuel cell 16 . The exhaust gas passage 66 has an upstream end connected to the fuel cell 16 and a downstream end connected to an external discharge destination (not shown). Exhaust gas is discharged from the fuel cell 16 to the discharge destination through the exhaust gas passage 66 .

The control unit 50 includes, for example, a CPU (not shown) and a storage unit 52 (for example, ROM and RAM), and performs various controls and operations related to the fuel cell system 2 according to programs stored in the storage unit 52. Execute the process.

The storage unit 52 of the control unit 50 stores ammonia concentration related information. FIG. 2 is a table showing an example of ammonia concentration related information. As shown in FIG. 2, the ammonia concentration relationship information indicates the relationship between temperature (horizontal axis) and pressure (vertical axis) and ammonia concentration (eg, 80%, 25%, . . . ). The temperature (horizontal axis (eg, 100° C., 200° C., . . The pressure (vertical axis (eg, 0 kPa, 100 kPa, . . . )) in the ammonia concentration relationship information corresponds to the reformed gas pressure detected by the pressure sensor 32 provided in the reformed gas supply passage 62 . The ammonia concentration (for example, 80%, 25%, . The ammonia concentration related information is created in advance based on experiments and analyses, for example. The ammonia concentration relation information is not limited to the table shown in FIG. 2, and may be represented by graphs or functions, for example. The control unit 50 estimates the concentration of ammonia contained in the reformed gas passing through the reformed gas supply passage 62 based on the temperature detected by the temperature sensor 30, the pressure detected by the pressure sensor 32, and the ammonia concentration relation information. do. For example, when the temperature detected by the temperature sensor 30 is 100° C. and the pressure detected by the pressure sensor 32 is 0 kPa, the control unit 50 adjusts the concentration of ammonia contained in the reformed gas to 80° C. based on the ammonia concentration relationship information. %.

(Heating amount control process; Figs. 3 and 4)
Next, the heating amount control process of the first embodiment will be described. The heating amount control process is started, for example, when there is an instruction to start the reformer 12 . When the heating amount control process is started, the first heater 40 (electric heater) provided in the reformer 12 is off. As shown in FIG. 3, in S10 of the heating amount control process, the control unit 50 sets the concentration of ammonia contained in the reformed gas estimated by the ammonia concentration relation information (see FIG. 2) to a predetermined first threshold value Th1 ( For example, 50%) or more. The ammonia concentration in S10 is specified based on the temperature detected by the temperature sensor 30, the pressure detected by the pressure sensor 32, and the ammonia concentration relationship information (see FIG. 2). The predetermined first threshold Th1 is a value less than a predetermined density tolerance Ta (eg, 60%) (see FIG. 4). The predetermined allowable concentration value Ta is set according to, for example, the ammonia removal capacity of the remover 14 . If it is determined in S10 that the ammonia concentration is equal to or higher than the first threshold Th1 (YES), the process proceeds to S12. If it is determined in S10 that the concentration of ammonia is less than the first threshold Th1 (NO), the process waits.

In S12 after YES in S10, the control unit 50 turns on the power of the first heater 40 (electric heater) provided in the reformer 12 (see FIG. 4). When the power of the first heater 40 is turned on, the first heater 40 generates heat to heat the raw material gas inside the reformer 12 . As a result, the temperature of the raw material gas rises and the reforming of the raw material gas is promoted. As a result, the decomposition of ammonia is accelerated and the concentration of ammonia contained in the reformed gas is reduced. The temperature of the reformed gas rises.

In subsequent S14, the control unit 50 determines whether the ammonia concentration contained in the reformed gas estimated from the ammonia concentration relation information (see FIG. 2) is less than a predetermined second threshold Th2 (for example, 10%). to decide. The ammonia concentration in S14 is specified based on the temperature detected by the temperature sensor 30, the pressure detected by the pressure sensor 32, and the ammonia concentration relationship information (see FIG. 2). The predetermined second threshold Th2 is a value less than the first threshold Th1 (see FIG. 4). If it is determined in S14 that the concentration of ammonia is less than the second threshold Th2 (YES), the process proceeds to S16. If it is determined in S14 that the ammonia concentration is equal to or greater than the second threshold Th2 (NO), the process returns to S12. In S12, the power of the first heater 40 (electric heater) is kept on, and the heating of the raw material gas by the first heater 40 is maintained.

In S16 after YES in S14, the control unit 50 turns off the power of the first heater 40 (electric heater) (see FIG. 4). When the first heater 40 is powered off, the first heater 40 stops heating the raw material gas. As a result, the concentration of ammonia contained in the reformed gas increases and the temperature of the reformed gas decreases.

In subsequent S18, the control unit 50 determines whether there is an instruction to stop the reformer 12 or not. If it is determined that there is an instruction to stop the reformer 12 (if YES), the heating amount control process ends. When it is determined that there is no instruction to stop the reformer 12 (in the case of NO), the process returns to S10. The control unit 50 repeats the above processing.

(effect)
The fuel cell system 2 of Example 1 has been described above. As described above, the fuel cell system 2 includes the reformer 12 that reforms the raw material gas to generate the reformed gas, the first heater 40 that heats the raw material gas in the reformer 12, and the reforming A reformed gas supply path 62 through which the reformed gas generated by the vessel 12 passes; a temperature sensor 30 that detects the temperature of the reformed gas passing through the reformed gas supply path 62; A fuel cell 16 that generates electricity by using the fuel gas generated by removing ammonia from the reformed gas, and the concentration of ammonia contained in the reformed gas estimated from the temperature detected by the temperature sensor 30. 1 and a control unit 50 that controls the amount of heating by the heater 40 .

According to the above configuration, it is possible to suppress the concentration of ammonia contained in the reformed gas while suppressing the heating amount in the reformer 12 . For example, when the concentration of ammonia estimated from the temperature detected by the temperature sensor 30 is high, it is estimated that the decomposition of ammonia is not promoted in the reformer 12 . In this case, by increasing the amount of heating by the first heater 40, the decomposition of ammonia can be promoted and the concentration of ammonia contained in the reformed gas can be suppressed. Further, when the concentration of ammonia estimated from the temperature detected by the temperature sensor 30 is low, it is estimated that the decomposition of ammonia is promoted in the reformer 12 . In this case, the amount of heating by the first heater 40 can be reduced. Since the amount of heating needs to be increased only when the decomposition of ammonia is not promoted, the amount of heating in the reformer 12 can be suppressed.

The fuel cell system 2 also includes a pressure sensor 32 that detects the pressure of the reformed gas passing through the reformed gas supply passage 62 . The control unit 50 controls the amount of heating by the first heater 40 according to the concentration of ammonia contained in the reformed gas estimated from the temperature detected by the temperature sensor 30 and the pressure detected by the pressure sensor 32 . According to this configuration, since the concentration of ammonia contained in the reformed gas is estimated from the temperature detected by the temperature sensor 30 and the pressure detected by the pressure sensor 32, the estimation accuracy is improved. Thereby, the heating amount by the first heater 40 can be controlled with high accuracy.

The control unit 50 increases the amount of heating by the first heater 40 when the concentration of ammonia contained in the reformed gas is estimated to be equal to or higher than a predetermined first threshold value Th1. According to this configuration, by increasing the amount of heating when the concentration of ammonia is high, the decomposition of ammonia can be promoted and the concentration of ammonia can be reduced.

The control unit 50 reduces the amount of heating by the first heater 40 when the concentration of ammonia contained in the reformed gas is estimated to be less than a predetermined second threshold Th2 that is less than the first threshold Th1. According to this configuration, unnecessary heating can be suppressed by reducing the heating amount when the concentration of ammonia is low.

The first heater 40 heats the raw material gas by Joule heat. According to this configuration, the amount of heating by the first heater 40 can be controlled with high accuracy.

The fuel cell system 2 includes a remover 14 that removes ammonia from the reformed gas that has passed through the reformed gas supply passage 62 to generate fuel gas. According to this configuration, it is possible to supply the fuel cell 16 with good quality fuel gas with a low concentration of ammonia. Further, if the structure can suppress the concentration of ammonia contained in the reformed gas, the amount of ammonia removed by the remover 14 can be suppressed, so the load on the remover 14 can be reduced. .

(Example 2)
Next, the fuel cell system 2 of Example 2 will be described. Below, the description of the same configuration as that of the first embodiment may be omitted. As shown in FIG. 5, the fuel cell system 2 of the second embodiment includes a second heater 42 (another example of the heating section) and a third heater 44 (another example of the heating section) provided in the reformer 12. example). The fuel cell system 2 of the second embodiment also includes a reformed gas branch channel 80 connected to the reformed gas supply channel 62 and an exhaust gas branch channel 90 connected to the exhaust gas channel 66 .

The upstream end of the reformed gas branch channel 80 is connected to the reformed gas supply channel 62 downstream of the temperature sensor 30 and the pressure sensor 32 and upstream of the heat exchanger 22 . In a modification, the upstream end of the reformed gas branch channel 80 may be connected to the reformed gas supply channel 62 upstream of the temperature sensor 30 and the pressure sensor 32 . A downstream end of the reformed gas branch passage 80 is connected to the second heater 42 provided in the reformer 12 . The reformed gas is supplied from the reformed gas supply passage 62 to the second heater 42 through the reformed gas branch passage 80 . The reformed gas discharged from the reformer 12 is supplied to the second heater 42 .

The reformed gas branch passage 80 is provided with a reformed gas valve 82 for opening and closing the reformed gas branch passage 80 . When the reformed gas valve 82 is opened, the reformed gas is supplied to the second heater 42 , and when the reformed gas valve 82 is closed, the reformed gas is not supplied to the second heater 42 .

The second heater 42 is a heat exchanger that heats and reforms the source gas by heat exchange between the reformed gas supplied from the reformed gas branch passage 80 and the source gas inside the reformer 12 . Cool the gas. The second heater 42 (heat exchanger) raises the temperature of the raw material gas by the heat of the reformed gas discharged from the reformer 12 .

The upstream end of the reformed gas return path 84 is connected to the second heater 42 . A downstream end of the reformed gas return path 84 is connected to the reformed gas supply path 62 downstream of the temperature sensor 30 and the pressure sensor 32 and upstream of the heat exchanger 22 . In a modification, the downstream end of the reformed gas return path 84 may be connected to the reformed gas supply path 62 downstream of the heat exchanger 22 . The reformed gas is supplied (returned) from the second heater 42 to the reformed gas supply passage 62 through the reformed gas return passage 84 .

The exhaust gas branch passage 90 has an upstream end connected to the exhaust gas passage 66 and a downstream end connected to the third heater 44 . Exhaust gas is supplied from the exhaust gas passage 66 to the third heater 44 through the exhaust gas branch passage 90 . Exhaust gas discharged from the fuel cell 16 is supplied to the third heater 44 .

An exhaust gas valve 92 for opening and closing the exhaust gas branch passage 90 is provided in the exhaust gas branch passage 90 . When the exhaust gas valve 92 is opened, the exhaust gas is supplied to the third heater 44 , and when the exhaust gas valve 92 is closed, the exhaust gas is no longer supplied to the third heater 44 .

The third heater 44 is a heat exchanger that heats the raw material gas and cools the raw material gas in the reformer 12 by heat exchange between the exhaust gas supplied from the exhaust gas branch passage 90 and the raw material gas inside the reformer 12 . The third heater 44 (heat exchanger) raises the temperature of the raw material gas with the heat of the exhaust gas discharged from the fuel cell 16 .

An upstream end of the second exhaust gas passage 94 is connected to the third heater 44 . A downstream end of the second exhaust gas passage 94 is connected to an external discharge destination (not shown), and the exhaust gas is discharged to the discharge destination through the second exhaust gas passage 94 .

(Heating amount control process; Fig. 6)
Next, the heating amount control process of the second embodiment will be described. When the heating amount control process of the second embodiment is started, the first heater 40 (electric heater) provided in the reformer 12 is off. Further, at the time when the heating amount control process of the second embodiment is started, the reformed gas valve 82 provided in the reformed gas branch passage 80 is closed, and the exhaust gas provided in the exhaust gas branch passage 90 is closed. The valve 92 is closed.

As shown in FIG. 6, in S12 of the heating amount control process of the second embodiment, the control unit 50 turns on the power of the first heater 40 (electric heater). Further, in S<b>12 , the control unit 50 opens the reformed gas valve 82 provided in the reformed gas branch passage 80 and the exhaust gas valve 92 provided in the exhaust gas branch passage 90 .

When the power of the first heater 40 is turned on, the first heater 40 generates heat to heat the raw material gas inside the reformer 12 . Further, when the reformed gas valve 82 is opened, the reformed gas is supplied to the second heater 42 through the reformed gas branch passage 80, and the source gas inside the reformer 12 is heated by the heat of the reformed gas. . Further, when the exhaust gas valve 92 is opened, the exhaust gas is supplied to the second heater 42 through the exhaust gas branch passage 90, and the source gas inside the reformer 12 is heated by the heat of the exhaust gas. As a result, the temperature of the raw material gas rises and the reforming of the raw material gas is promoted. As a result, the decomposition of ammonia is accelerated and the concentration of ammonia contained in the reformed gas is reduced.

As shown in FIG. 6, in S16 of the heating amount control process of the second embodiment, the controller 50 turns off the first heater 40 (electric heater). Further, in S16, the control unit 50 closes the reformed gas valve 82 provided in the reformed gas branch passage 80 and also closes the exhaust gas valve 92 provided in the exhaust gas branch passage 90. FIG.

When the first heater 40 is powered off, the first heater 40 stops heating the raw material gas. Further, when the reformed gas valve 82 is closed, the reformed gas is no longer supplied to the second heater 42, and heating of the raw material gas by the heat of the reformed gas stops. Further, when the exhaust gas valve 92 is closed, the exhaust gas is no longer supplied to the second heater 42, and the heating of the raw material gas by the heat of the exhaust gas stops. Thereby, the heating of the raw material gas by the second heater 42 is stopped.

(effect)
The fuel cell system 2 of the second embodiment has been described above. As described above, the fuel cell system 2 includes the second heater 42 that heats the source gas with the heat of the reformed gas produced by the reformer 12 . The fuel cell system 2 also includes a third heater 44 that heats the material gas with the heat of the exhaust gas discharged from the fuel cell 16 . The control unit 50 controls the amount of heating in the reformer 12 by opening and closing the reformed gas valve 82 provided in the reformed gas branch passage 80 . Further, the control unit 50 controls the heating amount in the reformer 12 by opening and closing an exhaust gas valve 92 provided in the exhaust gas branch passage 90 .

According to this configuration, the raw material gas can be heated by effectively utilizing the heat of the reformed gas. Also, by effectively utilizing the heat of the exhaust gas from the fuel cell 16, the raw material gas can be heated. With this configuration, similarly to the first embodiment, it is possible to suppress the concentration of ammonia contained in the reformed gas while suppressing the heating amount in the reformer 12 .

Moreover, according to the above configuration, it is possible to lower the temperature of the reformed gas by utilizing the increase in the temperature of the raw material gas. Thereby, the temperature of the reformed gas supplied to the remover 14 can be lowered, and the removal of ammonia in the remover 14 can be promoted. Also, the temperature of the exhaust gas can be lowered by using the temperature rise of the raw material gas. As a result, the temperature of the exhaust gas discharged to the outside can be lowered, and the exhaust gas can be safely discharged.

(Modification)
(1) In Examples 1 and 2 above, the ammonia concentration relationship information (see FIG. 2) for estimating the concentration of ammonia contained in the reformed gas indicates the relationship between the temperature and pressure and the concentration of ammonia. Information, but not limited to. In a modification, as shown in FIG. 7, the ammonia concentration relationship information may be information indicating the relationship between temperature and ammonia concentration. The temperature (horizontal axis (eg, 100° C., 200° C., . corresponds to The ammonia concentration (for example, 80%, 25%, . The control unit 50 estimates the concentration of ammonia contained in the reformed gas passing through the reformed gas supply path 62 based on the temperature detected by the temperature sensor 30 and the ammonia concentration relationship information. In a variant, the pressure sensor 32 can be omitted.

(2) In a modification, the controller 50 may be configured to control the amount of heating by adjusting the amount of electricity supplied to the first heater 40 (electric heater). For example, the control unit 50 may decrease the amount of heating by decreasing the amount of electricity supplied to the first heater 40 and increase the amount of heating by increasing the amount of electricity supplied to the first heater 40 . The controller 50 does not necessarily have to turn on/off the first heater 40 .

(3) In a modification, the control unit 50 may be configured to control the heating amount by adjusting the opening degree of the reformed gas valve 82 provided in the reformed gas branch passage 80 . For example, the control unit 50 may decrease the amount of heating by decreasing the degree of opening of the reformed gas valve 82 and increase the amount of heating by increasing the degree of opening of the reformed gas valve 82 . The control unit 50 does not necessarily have to open/close the reformed gas valve 82 .

(4) In a modified example, the control unit 50 may be configured to control the heating amount by adjusting the opening degree of the exhaust gas valve 92 provided in the exhaust gas branch passage 90 . For example, the control unit 50 may decrease the amount of heating by decreasing the opening of the exhaust gas valve 92 and increase the amount of heating by increasing the opening of the exhaust gas valve 92 . The control unit 50 does not necessarily have to open/close the exhaust gas valve 92 .

(5) In a modification, the fuel cell system 2 may be configured to include one or two of the first heater 40, the second heater 42 and the third heater 44. Any one or two of the first heater 40, the second heater 42 and the third heater 44 may be omitted.

(6) In a modified example, the controller 50 may electrify the first heater 40 (electric heater) with power generated by the fuel cell 16 .

(7) In a modification, the vaporizer 20 may be omitted. In this case, the fuel cell system 2 may have a gas cylinder (not shown) instead of the raw material tank 10 . The gas cylinder stores raw material gas (for example, ammonia gas, hydrocarbon gas, formic acid gas, hydrazine gas, etc.). A source gas supply path 60 is connected to the gas cylinder. Note that when a raw material gas other than ammonia gas is used, ammonia is produced as a by-product in the reformer 12 .

(8) In a modification, the remover 14 may be configured to remove ammonia by passing the reformed gas through water.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or in the drawings exhibit technical utility either singly or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques exemplified in this specification or drawings can simultaneously achieve a plurality of purposes, and achieving one of them has technical utility in itself.

2: fuel cell system, 10: raw material tank, 12: reformer, 14: remover, 16: fuel cell, 20: vaporizer, 22: heat exchanger, 30: temperature sensor, 32: pressure sensor, 40: First heater 42: Second heater 44: Third heater 50: Control unit 52: Storage unit 60: Source gas supply path 62: Reformed gas supply path 64: Fuel gas supply path , 66: Exhaust gas channel, 68: Air supply channel, 70: Liquid supply channel, 72: Pump, 80: Reformed gas branch channel, 82: Reformed gas valve, 84: Reformed gas return channel, 90: Exhaust gas branch channel, 92: Exhaust gas valve, 94: Second exhaust gas passage

Claims (9)

a reformer for generating a reformed gas by reforming the raw material gas;
a heating unit for heating the raw material gas in the reformer;
a gas passage through which the reformed gas generated by the reformer passes;
a temperature sensor that detects the temperature of the reformed gas passing through the gas passage;
a fuel cell that generates electricity using a fuel gas generated by removing ammonia from the reformed gas that has passed through the gas passage;
and a control unit that controls the amount of heating by the heating unit according to the concentration of ammonia contained in the reformed gas estimated from the temperature detected by the temperature sensor. The fuel cell system according to claim 1,
further comprising a pressure sensor that detects the pressure of the reformed gas passing through the gas passage;
The control unit controls the amount of heating by the heating unit according to the concentration of ammonia contained in the reformed gas estimated from the temperature detected by the temperature sensor and the pressure detected by the pressure sensor. 3. The fuel cell system according to claim 1 or 2,
The fuel cell system, wherein the control unit increases the amount of heating by the heating unit when the concentration of ammonia contained in the reformed gas is estimated to be equal to or higher than a predetermined first threshold value. The fuel cell system according to any one of claims 1 to 3,
The fuel cell system, wherein the control unit reduces the amount of heating by the heating unit when the concentration of ammonia contained in the reformed gas is estimated to be less than a predetermined second threshold. The fuel cell system according to claim 4 citing claim 3,
The fuel cell system, wherein the second threshold is less than the first threshold. The fuel cell system according to any one of claims 1 to 5,
The fuel cell system, wherein the heating unit includes a first heater that heats the raw material gas by Joule heat. The fuel cell system according to any one of claims 1 to 6,
The fuel cell system, wherein the heating unit includes a second heater that heats the raw material gas with heat of the reformed gas generated by the reformer. The fuel cell system according to any one of claims 1 to 7,
The fuel cell system, wherein the heating unit includes a third heater that heats the raw material gas with heat of exhaust gas discharged from the fuel cell. The fuel cell system according to any one of claims 1 to 8,
The fuel cell system further comprising a remover that removes ammonia from the reformed gas that has passed through the gas passage to generate the fuel gas.

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