JP2018002508A - Hydrogen generation device and fuel cell system with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for avoiding error detection of gas leakage by a microcomputer meter while suppressing deterioration of a catalyst.SOLUTION: The hydrogen generation device (200) has a reformer (1), an electric heater (5) heating the reformer (1), a gas supply passage (6) connected to the reformer (1) for supplying a raw material gas to the reformer (1), a valve (7) arranged in the gas supply passage (6), and a controller (30) conducting control for energizing the electric heater (5) so that the reformer (1) is heated with keeping the valve (7) closed when operation of the hydrogen generation device (200) is stopped.SELECTED DRAWING: Figure 6

Description

  The present disclosure relates to a hydrogen generator and a fuel cell system including the same.

  Fuel cell systems including a reformer and a fuel cell are well known. In the reformer, hydrogen gas is generated from the raw material gas such as city gas by the reforming reaction. The generated hydrogen gas is supplied to the fuel cell together with oxygen (air) as an oxidant gas. In a fuel cell, electric power is generated by an electrochemical reaction between hydrogen and oxygen.

  The reformer is heated to produce hydrogen gas by steam reforming. When the operation of the fuel cell system is stopped or temporarily stopped (for example, when the amount of hot water in the hot water storage tank reaches a specified value), heating of the reformer is also stopped. When the heating of the reformer is stopped, the raw material gas remaining inside the reformer is adsorbed on the catalyst, and the internal pressure of the reformer decreases. Then, air enters the interior of the reformer, and the air is adsorbed by a catalyst such as a reforming catalyst. Air (especially oxygen) adsorbed on the catalyst promotes deterioration of the catalyst. In order to suppress the deterioration of the catalyst due to the adsorption of air, the interior of the reformer is purged with a raw material gas when the fuel cell system is stopped (Patent Document 1).

JP 2005-162580 A JP 2004-258767 A

  By the way, a flow meter for measuring the flow rate of the raw material gas (specifically, the amount of the raw material gas used) on the path for supplying the raw material gas from the raw material gas source to the reformer. Is provided. The detection signal of the flow meter is sent to a gas meter equipped with a microcomputer. A gas meter equipped with a microcomputer is often called a “micrometer”. The microcomputer meter has not only a function of recording the gas flow rate but also a function of detecting a gas leak.

  The gas leak detection function of the microcomputer meter does not take into account the long-term use of the fuel cell system and the capacity increase of the reformer. Therefore, there is a possibility that the microcomputer meter erroneously detects a gas leak.

  The objective of this indication is providing the technique for avoiding the misdetection of the gas leak by a microcomputer meter, suppressing the deterioration of a catalyst.

That is, this disclosure
A hydrogen generator,
A reformer,
An electric heater for heating the reformer;
A gas supply path connected to the reformer for supplying a raw material gas to the reformer;
A valve provided in the gas supply path;
A controller that executes control to energize the electric heater so that the reformer is heated while the valve is closed when the operation of the hydrogen generator is stopped;
A hydrogen generation apparatus is provided.

  According to the technology of the present disclosure, it is possible to avoid erroneous detection of gas leakage by the microcomputer meter while suppressing deterioration of the catalyst.

FIG. 1 is a configuration diagram of a fuel cell system according to an embodiment of the present disclosure. FIG. 2 is a schematic sectional view of the reformer. FIG. 3 is a time chart showing an operation cycle of the fuel cell system. FIG. 4 is a flowchart showing a standby start process to be executed in the controller at the transition timing from the stop period to the standby period. FIG. 5 is a flowchart showing a standby process to be executed during the standby period of the fuel cell system. FIG. 6 is a configuration diagram of a hydrogen generator according to a modified example of the present disclosure.

(Knowledge that became the basis of this disclosure)
The gas leak detection function of the microcomputer meter is constituted by the following algorithm, for example. The microcomputer meter continuously records the gas usage based on the detection signal acquired from the flow meter. At the same time, it is determined whether or not the gas consumption per unit time is substantially zero (for example, 1.0 liter / h or less) every unit time (for example, 1 hour). When the time zone in which the amount of gas used per unit time is substantially zero does not exist once in a predetermined period (for example, 30 days), the microcomputer meter determines that gas is leaking and issues a warning.

  When the microcomputer meter has the gas leak detection function as described above, it is difficult to continuously operate the fuel cell system for a long period of time. Furthermore, as described in Patent Document 1, if the raw material gas is continuously used to purge the interior of the reformer with the raw material gas when the fuel cell system is stopped, the amount of gas used is substantially reduced. It is difficult to make a zero time zone. If the time period in which the gas usage is substantially zero cannot be made within the predetermined period, the microcomputer meter detects a gas leak even if the gas usage is appropriate. This problem becomes apparent when a reformer having a large capacity is used, when a catalyst that easily adsorbs a raw material gas is used, or when a raw material gas that is easily adsorbed by the catalyst is used.

The hydrogen generator according to the first aspect of the present disclosure includes:
A reformer,
An electric heater for heating the reformer;
A gas supply path connected to the reformer for supplying a raw material gas to the reformer;
A valve provided in the gas supply path;
A controller that executes control to energize the electric heater so that the reformer is heated while the valve is closed when the operation of the hydrogen generator is stopped;
It is equipped with.

  According to the first aspect of the present disclosure, the temperature inside the reformer, in other words, the temperature of the catalyst can be maintained at a high temperature by the electric heater. As a result, it is possible to suppress the raw material gas from being adsorbed on the catalyst as the temperature of the catalyst decreases. As a result, a decrease in the internal pressure of the reformer is suppressed, so that air can be prevented from entering the reformer. Since it is not necessary to purge a large amount of raw material gas into the reformer, it is possible to avoid erroneous detection of gas leakage by a gas meter.

  In the second aspect of the present disclosure, for example, the controller of the hydrogen generator according to the first aspect is configured so that the reformer is heated while the valve is closed only during a predetermined essential waiting period. While performing control to energize the electric heater, when the operation of the hydrogen generator other than the essential standby period is stopped, the valve is opened while the electric heater is kept off, and the raw material is supplied to the reformer. Control to fill the gas is executed. In this way, the frequency of use of the electric heater can be reduced, so that power consumption can be further suppressed.

  In the third aspect of the present disclosure, for example, when the operation of the hydrogen generator according to the first or second aspect is stopped, the controller is configured to heat the reformer while the valve is closed. And a control for opening the valve so that the supply amount of the raw material gas per unit time to the reformer falls below a threshold value. In this way, even if the raw material gas is adsorbed to the catalyst to some extent, a decrease in the internal pressure of the reformer is reliably suppressed, so that air can be prevented from entering the interior of the reformer.

  In the fourth aspect of the present disclosure, for example, the hydrogen generator according to any one of the first to third aspects further includes a temperature sensor that detects a temperature inside the reformer, and the controller includes: Based on the detection signal of the temperature sensor, on / off of the electric heater is controlled. If it does in this way, the power consumption by an electric heater can be controlled, preventing the fall of the temperature of a reformer.

A fuel cell system according to a fifth aspect of the present disclosure includes:
Any one of the hydrogen generators according to the first to fourth aspects;
A fuel cell that generates electric power using hydrogen gas generated by the reformer of the hydrogen generator;
It is equipped with.

The operation method of the hydrogen generator according to the sixth aspect of the present disclosure is as follows.
Supplying raw material gas to the reformer, reforming the raw material gas while heating the reformer with a combustor, and generating hydrogen gas;
Switching a valve provided in a gas supply path for supplying the raw material gas to the reformer from an open state to a closed state to stop the generation of the hydrogen gas;
Heating the reformer by energizing an electric heater provided in the reformer while the valve is closed;
Is included.

  According to the 5th aspect and the 6th aspect, the same effect as a 1st aspect is acquired.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

As shown in FIG. 1, a fuel cell system 100 according to an embodiment of the present disclosure includes a reformer 1 and a fuel cell 2. The reformer 1 is a device for generating hydrogen gas by a reforming reaction such as a steam reforming reaction (CH ₄ + H ₂ O → CO + 3H ₂ ). The reformer 1 contains a reforming catalyst for advancing the reforming reaction. The reformer 1 also contains a catalyst for removing carbon monoxide (a CO conversion catalyst and a CO selective oxidation removal catalyst). The reformer 1 generates hydrogen gas using water and raw material gas. The source gas is, for example, a hydrocarbon gas such as city gas or LP gas (liquefied petroleum gas). Hydrogen gas generated by the reformer 1 is supplied to the fuel cell 2. The fuel cell 2 generates electric power using oxidant gas and hydrogen gas. The fuel cell 2 is, for example, a solid polymer fuel cell. Hot water is generated by the exhaust heat of the fuel cell 2. The generated hot water is stored in a hot water storage tank (not shown).

  A gas supply path 6 and a water supply path 22 are connected to the reformer 1. The gas supply path 6 is connected to the gas meter 20. The gas supply path 6 is a path for supplying the source gas to the reformer 1 from a source gas source such as a city gas infrastructure or a gas cylinder. In the gas supply path 6, a valve 7, a desulfurizer 8 and a pump 9 are arranged. The valve 7 is an on-off valve, for example. The valve 7 may be a flow control valve. The desulfurizer 8 is a device for removing sulfur compounds contained in the raw material gas from the fuel. The pump 9 is a pump for increasing the pressure of the source gas. By controlling the pump 9, the flow rate of the source gas can be adjusted. The water supply path 22 is a path for supplying water to the reformer 1 from a water source such as a water storage tank (not shown). The pump 10 is disposed in the water supply path 22. The water supplied to the reformer 1 is heated and vaporized by the evaporator 3 provided in the reformer 1, and is led to the reforming catalyst layer together with the raw material gas.

  The gas meter 20 is, for example, a microcomputer meter incorporating an ultrasonic flow meter and a microcomputer. The amount of gas used measured by the ultrasonic flowmeter is recorded in the microcomputer. The type of flow meter is not particularly limited.

  The reformer 1 is connected to the fuel cell 2 by a fuel gas supply path 11. The hydrogen gas generated by the reformer 1 is supplied to the fuel cell 2 via the fuel gas supply path 11.

  The fuel cell system 100 further includes a combustor 4 and an electric heater 5. The combustor 4 is a device for heating the reformer 1 by burning fuel. The combustor 4 is provided adjacent to the reformer 1.

  An example of the electric heater 5 is a resistance heating type sheathed heater (sheathed heater) built in the reformer 1. The electric heater 5 is attached to the outer peripheral surface of a container in which a catalyst such as a reforming catalyst is disposed, for example. If the fuel device 4 and the electric heater 5 are used in combination, the temperature of the catalyst can be quickly raised when the fuel cell system 100 is started. A plurality of electric heaters 5 that can be independently controlled on / off may be incorporated in the reformer 1. In this case, stepwise temperature adjustment is possible. Electric power can be supplied to the electric heater 5 from a commercial power source.

  The temperature of the catalyst can be detected by a temperature sensor 21 disposed inside the reformer 1. An example of the temperature sensor 21 is a thermistor or a thermocouple. A plurality of temperature sensors 21 may be provided inside the reformer 1. Each temperature sensor 21 can individually detect the temperature of the reforming catalyst, the temperature of the CO shift catalyst, the temperature of the CO selective oxidation removal catalyst, and the like.

  An oxidant gas supply path 14 is connected to the fuel cell 2. The oxidant gas supply path 14 is a path for supplying an oxidant gas such as oxygen to the fuel cell 2. A blower 15, a humidifier 16 and a valve 17 are disposed in the oxidant gas supply path 14. The valve 17 is an on-off valve, for example.

  A fuel gas discharge path 12 and an oxidant gas discharge path 18 are further connected to the fuel cell 2. Hydrogen gas and unreacted raw material gas that have not been consumed in the fuel cell 2 are supplied to the combustor 4 via the fuel gas discharge path 12 and burned in the combustor 4. The oxidant gas that has not been consumed in the fuel cell 2 is discharged to the outside via the oxidant gas discharge path 18. A valve 19 is disposed in the oxidant gas discharge path 18. The valve 19 is an on-off valve, for example.

  The fuel cell system 100 further includes a controller 30. The controller 30 controls controlled objects such as the combustor 4, the electric heater 5, the valve 7, the pump 9, the pump 10, the blower 15, the valve 17, and the valve 19. Detection signals are input to the controller 30 from various sensors such as the temperature sensor 21. As the controller 30, a DSP (Digital Signal Processor) including an A / D conversion circuit, an input / output circuit, an arithmetic circuit, a storage device, and the like can be used. The controller 30 stores a program for properly operating the fuel cell system 100.

  Each path such as the gas supply path 6 may be constituted by a pipe such as a metal pipe or a resin pipe.

  Next, an example of the structure of the reformer 1 will be described in detail.

  As shown in FIG. 2, the reformer 1 includes a container 41, an outer cylinder 42, and an inner cylinder 43. An outer cylinder 42 is disposed inside the container 41. An inner cylinder 43 is disposed inside the outer cylinder 42. That is, the reformer 1 has a three-layer shell structure. Between the outer peripheral surface of the inner cylinder 43 and the inner peripheral surface of the outer cylinder 42, a flow path 61 having a donut-shaped cross-sectional shape is formed. Between the inner peripheral surface of the container 41 and the outer peripheral surface of the outer cylinder 42, a flow path 62 having a donut-shaped cross-sectional shape is formed. The flow path 61 communicates with the flow path 62 through a through hole 42 h provided in the bottom of the outer cylinder 42. The gas supply path 6 is connected to the most upstream portion of the flow path 61 through the raw material gas inlet 51, and the water supply path 22 is connected to the reformed water inlet 52. A part of the flow path 61 serves as the evaporator 3 shown in FIG. A reforming catalyst 45 is disposed in the flow path 61. A CO shift catalyst 47 and a CO selective oxidation removal catalyst 49 are disposed in the flow path 62. An air supply path 60 is connected to the flow path 62 through an air inlet 53 provided in the container 41 on the downstream side of the CO conversion catalyst 47 and the upstream side of the CO selective oxidation removal catalyst 49. The fuel gas supply path 11 is connected to the most downstream portion of the flow path 62 through the fuel gas outlet 54.

  A temperature sensor 21 a is disposed in the flow path 61 in the vicinity of the reforming catalyst 45. In the flow path 62, the temperature sensor 21 b is disposed in the vicinity of the CO conversion catalyst 47, and the temperature sensor 21 c is disposed in the vicinity of the CO selective oxidation removal catalyst 49. The temperature of the reforming catalyst 45 is detected by the temperature sensor 21a. The temperature of the CO shift catalyst 47 is detected by the temperature sensor 21b. The temperature of the CO selective oxidation removal catalyst 49 is detected by the temperature sensor 21b. These temperature sensors 21a to 21c correspond to the temperature sensor 21 shown in FIG.

  The combustor 4 is disposed in the internal space 63 of the inner cylinder 43. A fuel gas discharge path 12 is connected to the combustor 4. The fuel gas discharge path 12 is a path for guiding the remaining hydrogen gas and unreacted raw material gas from the fuel cell 2 to the combustor 4. An exhaust gas path 65 is connected to the inner cylinder 43 through a combustion exhaust gas outlet 57. As indicated by the alternate long and short dash line, the combustion exhaust gas is discharged outside the fuel cell system 100 through the exhaust gas path 65.

  The electric heater 5 is disposed around the container 41 so as to surround the CO conversion catalyst 47 and the CO selective oxidation removal catalyst 49. Specifically, the electric heater 5 is wound around the container 41. In FIG. 2, the electric heater 5 is disposed only around the CO shift catalyst 47 and the CO selective oxidation removal catalyst 49. However, the electric heater 5 may be disposed around the reforming catalyst 45. Further, the electric heater 5 may be arranged in at least one selected from the flow path 61 and the flow path 62.

  When hydrogen gas and unreacted source gas are burned in the combustor 4, the inner cylinder 43 is heated. The heat of the inner cylinder 43 is transmitted to the reforming catalyst 45, and the temperature of the reforming catalyst 45 can be raised. Further, the reformed gas containing hydrogen gas flows from the flow path 61 to the flow path 62, and the temperature of the CO shift catalyst 47 and the temperature of the CO selective oxidation removal catalyst 49 also rise due to the heat of the reformed gas. The electric heater 5 may be energized to heat the CO shift catalyst 47 and the CO selective oxidation removal catalyst 49 with the electric heater 5. When the electric heater 5 is in the vicinity of the reforming catalyst 45, the electric heater 5 can be energized to heat the reforming catalyst 45 with the electric heater 5. During the start-up period of the fuel cell system 100, when the temperature of the catalyst is not sufficiently increased, most of the raw material gas is guided to the combustor 4 via the reformer 1 and the fuel cell 2 without being reacted. As the temperature of the catalyst rises, the reforming reaction proceeds efficiently, and the hydrogen gas concentration in the reformed gas also rises. In order to quickly increase the temperature of the catalyst, the electric heater 5 can be used during the startup period of the fuel cell system 100.

  Next, the operation of the fuel cell system 100 will be described.

  As shown in FIG. 3, the fuel cell system 100 can be operated mainly according to four operation cycles of a start period, a power generation period, a stop period, and a standby period. The “activation period” is an operation period for activating the fuel cell system 100. Specifically, the “startup period” is an operation period for gradually increasing the output of the fuel cell system 100 to a predetermined rated output (for example, 750 W). In the start-up period, the supply flow rate of the raw material gas and the supply flow rate of water to the reformer 1 are gradually increased. During the start-up period, the flow rate of the oxidant gas and the flow rate of the hydrogen gas gradually increase. The “power generation period” is a period during which the fuel cell system 100 is operated at a predetermined rated output. However, it is not essential that the fuel cell system 100 is always operated at the rated output during the power generation period. A period during which the fuel cell system 100 is stably operated at a constant output is a “power generation period”. During the power generation period, the supply flow rate of the raw material gas and the supply flow rate of water to the reformer 1 are kept constant. The flow rate of the oxidant gas and the flow rate of the hydrogen gas are also kept constant. The “stop period” is an operation period for stopping the fuel cell system 100. Specifically, the “stop period” is an operation period for gradually reducing the output of the fuel cell system 100 to zero. In the stop period, the supply flow rate of the raw material gas and the supply flow rate of water to the reformer 1 are gradually decreased. During the stop period, the flow rate of the oxidant gas and the flow rate of the hydrogen gas gradually decrease. The “standby period” is a period in which the output of the fuel cell system 100 is maintained at zero. During the standby period, the supply flow rate of the raw material gas and the supply flow rate of water to the reformer 1 are basically zero. However, as will be described later, in order to suppress deterioration of the reformer 1, the reformer 1 may be periodically purged with a raw material gas. The controller 30 continues to execute predetermined electrical processing during the standby period. An example of such an electrical process is a process for monitoring the amount of hot water in a hot water storage tank.

  According to the example of FIG. 3, the output of the fuel cell system 100 increases or decreases continuously and at a constant rate during the start-up period and the stop period. However, the output of the fuel cell system 100 may be increased or decreased in stages. Furthermore, the rate of increase or decrease in output may be changed.

  In one example, the length of the start period and the length of the stop period are each in the range of 10 minutes to 90 minutes. By spending sufficient time to start or stop the fuel cell system 100, it is possible to suppress the deterioration of the reformer 1, the deterioration of the fuel cell 2, and the like. The length of the power generation period and the length of the standby period vary according to the time during which the fuel cell system 100 can be operated continuously, the capacity of the hot water storage tank, and the like. When a sufficient amount of hot water is stored in the hot water storage tank, the fuel cell system 100 automatically stops operation and enters a standby period. When the amount of hot water in the hot water storage tank falls below the threshold, the fuel cell system 100 automatically starts operation. When the amount of hot water used is large, the waiting period may be zero in one operation cycle.

  In the present embodiment, the longest continuous operation time of the fuel cell system 100 is, for example, 24 to 240 hours. When the longest continuous operation time is sufficiently long, the start-up period and the stop period become relatively short, so that improvement in the efficiency of the fuel cell system 100 can be expected. Deterioration of components such as the reformer 1 and the fuel cell 2 can also be suppressed.

  As explained above, the gas meter 20 continues to record gas usage. When there is no time zone in which the amount of gas used per unit time (for example, 1 hour) is substantially zero (for example, 1.0 liter / h or less) once in a predetermined period (for example, 30 days), the gas meter 20 determines that gas is leaking and issues a warning. Even if the use of gas is appropriate, the gas meter 20 detects a gas leak. In other words, the gas meter 20 erroneously detects a gas leak. According to the method described below, it is possible to avoid erroneous detection of gas leakage by the gas meter 20 while preventing deterioration of the catalyst in the reformer 1.

  FIG. 4 shows a standby start process to be executed in the controller 30 at the transition timing from the stop period to the standby period. In step S1, for example, supply of air to the combustor 4 is stopped, and the combustor 4 is stopped (step S1). That is, heating of the reformer 1 by the combustor 4 is stopped. In step S2, the valve 7 is closed. In other words, the generation of hydrogen gas is stopped by switching the valve 7 from the open state to the closed state. In step S3, the electric heater 5 is turned on. The order of processing in steps S1 to S3 is not limited, and may be interchanged with each other, or these may be performed simultaneously. The electric heater 5 is kept on until the fuel cell system 100 is started next time, for example. That is, the reformer 1 is heated by energizing the electric heater 7 with the valve 7 closed. The valve 17 disposed in the oxidant gas supply path 14 and the valve 19 disposed in the oxidant gas discharge path 18 may be closed.

  When the operation of the fuel cell system 100 is stopped (when shifting from the stop period to the standby period), the valve 7 is closed and the supply of the raw material gas to the reformer 1 is stopped. Even if the valve 7 is closed, for example, air can enter the reformer 1 via the combustor 4, the fuel gas discharge path 12, the fuel cell 2, and the fuel gas supply path 11.

  According to this embodiment, even if heating of the reformer 1 by the fuel device 4 is stopped, the temperature inside the reformer 1, in other words, the temperature of the catalyst can be maintained at a high temperature by the electric heater 5. . As a result, it is possible to suppress the raw material gas from being adsorbed on the catalyst as the temperature of the catalyst decreases. Since the lowering of the internal pressure of the reformer 1 is suppressed, it is possible to suppress the intrusion of air into the reformer 1 via the above path. Since it is not necessary to purge a large amount of raw material gas into the reformer 1, it is possible to avoid erroneous detection of gas leakage by a gas meter. When the reformer 1 has the structure shown in FIG. 2, the CO heater 47 and the CO selective oxidation removal catalyst 49 are mainly heated by the electric heater 5. However, the arrangement of the electric heater 5 is not limited to the example of FIG. The catalyst to be kept at a high temperature by the action of the electric heater 5 is at least one selected from the reforming catalyst 45, the CO shift catalyst 47, and the CO selective oxidation removal catalyst 49.

  In the standby period, the electric heater 5 may be always on, or the on / off of the electric heater 5 may be switched periodically.

  In order to suppress power consumption by the electric heater 5, for example, when the operation of the fuel cell system 100 is stopped during a predetermined essential standby period, control for energizing the electric heater 5 may be executed. The predetermined essential waiting period is a period that should be secured at a frequency that can prevent erroneous detection of gas leakage by the gas meter 20. The predetermined essential waiting period is, for example, a period secured once or a plurality of times every 30 days. Specifically, only in the essential standby period, control for energizing the electric heater 5 while the valve 7 is closed can be executed. When the operation of the fuel cell system 100 other than the essential standby period is stopped (standby period), control is performed to open the valve 7 and fill the reformer 1 with the raw material gas while maintaining the electric heater 5 off. Is done. That is, in the standby period other than the essential standby period, the reformer 1 is purged with the raw material gas, thereby preventing air from entering the reformer 1. In this way, the frequency of use of the electric heater 5 can be reduced, so that power consumption can be further suppressed.

  Further, if it is possible to prevent erroneous detection of gas leakage by the gas meter 20, it is permitted to open the valve 7 and supply the raw material gas to the reformer 1 even in the essential standby period. That is, both the control for opening the valve 7 for a short time and purging the reformer 1 with the raw material gas and the control for energizing the electric heater 5 may be executed. Specifically, when the operation of the fuel cell system 100 is stopped, the control to energize the electric heater 5 so that the reformer 1 is heated while the valve 7 is closed, and the unit time to the reformer 1 The control of opening (opening and closing) the valve 7 is executed so that the supply amount of the raw material gas per unit falls below a threshold value (for example, 1.0 L / h). In this way, even if the raw material gas is adsorbed to the catalyst to some extent, a decrease in the internal pressure of the reformer 1 is reliably suppressed, so that it is possible to suppress the intrusion of air into the reformer 1. As long as the supply amount of the raw material gas per unit time to the reformer 1 is less than the threshold value, the opening / closing control of the valve 7 may be executed a plurality of times in the standby period.

  In the standby period, on / off of the electric heater 5 may be controlled according to the temperature inside the reformer 1. Specifically, during the standby period, the standby processing shown in the flowchart of FIG. 5 is periodically executed. In step S11, the temperature T of the reformer 1 is detected. Specifically, the controller 30 acquires a detection signal from the temperature sensor 21. The temperature T inside the reformer 1 is specified from the detection signal of the temperature sensor 21. In step S12, it is determined whether the temperature T is equal to or higher than the threshold temperature TH. If the temperature T is equal to or higher than the threshold temperature TH, the electric heater 5 is turned off (step S13). If the temperature T is lower than the threshold temperature TH, the electric heater 5 is turned on (step S14). In this way, power consumption by the electric heater 5 can be suppressed while preventing a temperature drop of the reformer 1.

  The temperature T may be a temperature detected by one temperature sensor selected from the temperature sensors 21a, 21b and 21c (FIG. 2), or may be the highest of the three temperatures detected by the temperature sensors 21a, 21b and 21c. It may be a low temperature or an average value of three temperatures. The temperature of the catalyst that most easily adsorbs the source gas among the reforming catalyst 45, the CO shift catalyst 47, and the CO selective oxidation removal catalyst 49 may be handled as the temperature T.

  The threshold temperature TH is desirably a temperature at which adsorption of gas (raw material gas or air) to the catalyst can be sufficiently suppressed. The threshold temperature TH is set within a range of 100 to 120 ° C., for example. The control shown in the flowchart of FIG. 5 may be executed during the essential standby period described above, or may be executed when the purge of the source gas and the energization of the electric heater 5 are used in combination.

(Modification)
A part of the fuel cell system 100 can be used as a hydrogen generator. As shown in FIG. 6, in the hydrogen generator 200, the fuel cell 2 in FIG. 1 is replaced with the hydrogen storage facility 32, the oxidant gas supply path 14 is omitted, and the fuel gas discharge path 12 is omitted. Except for this, the fuel cell system 100 has the same configuration. The hydrogen gas generated in the reformer 1 is liquefied and liquid hydrogen is stored in the hydrogen storage facility 32. The hydrogen storage facility 32 includes a liquefier for liquefying hydrogen gas, a tank for storing liquid hydrogen, and the like.

  The technology disclosed in this specification is useful for a fuel cell system, a hydrogen station, a hydrogen production plant, and the like. The technique disclosed in this specification is particularly useful when a catalyst that easily adsorbs a raw material gas is used as a catalyst for a reformer.

DESCRIPTION OF SYMBOLS 1 Reformer 2 Fuel cell 4 Combustor 5 Electric heater 6 Gas supply path 7 Valve 21 Temperature sensor 30 Controller 100 Fuel cell system 200 Hydrogen generator

Claims (6)

A hydrogen generator,
A reformer,
An electric heater for heating the reformer;
A gas supply path connected to the reformer for supplying a raw material gas to the reformer;
A valve provided in the gas supply path;
A controller that executes control to energize the electric heater so that the reformer is heated while the valve is closed when the operation of the hydrogen generator is stopped;
A hydrogen generator comprising:   The controller performs control for energizing the electric heater so that the reformer is heated while the valve is closed only during a predetermined essential waiting period, while the hydrogen other than the essential waiting period is used. 2. The hydrogen generator according to claim 1, wherein when the generator is stopped, the valve is opened and the reformer is charged with the raw material gas while the electric heater is kept off.   When the operation of the hydrogen generator is stopped, the controller controls the energization of the electric heater so that the reformer is heated while the valve is closed, and the unit time to the reformer The hydrogen generation apparatus according to claim 1 or 2, wherein the control is performed such that the valve is opened so that a supply amount of the source gas per unit falls below a threshold value. A temperature sensor for detecting the temperature inside the reformer;
The hydrogen generator according to any one of claims 1 to 3, wherein the controller controls on / off of the electric heater based on a detection signal of the temperature sensor. The hydrogen generator according to any one of claims 1 to 4,
A fuel cell that generates electric power using hydrogen gas generated by the reformer of the hydrogen generator;
A fuel cell system comprising: Supplying raw material gas to the reformer, reforming the raw material gas while heating the reformer with a combustor, and generating hydrogen gas;
Switching a valve provided in a gas supply path for supplying the raw material gas to the reformer from an open state to a closed state to stop the generation of the hydrogen gas;
Heating the reformer by energizing an electric heater provided in the reformer while the valve is closed;
A method for operating a hydrogen generator, comprising:

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