JP2009035480A - Shutdown method of hydrogen producing system operation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shutdown hydrogen producing system operation without an inert gas. <P>SOLUTION: Operation is shutdown by purging residual gas in the system by the following procedure in a system producing hydrogen gas by reforming gasoline and the like. A raw material and air are firstly stopped to feed to a reform unit while continuing to feed steam. Accordingly, the gas in the system is purged by the steam. Steam purge is stopped to change to air purge when an environmental condition is set so as not to abnormally combust by the steam purge even if oxygen is fed. The steam is eliminated from the system so that adverse effects by dew condensation are avoided thereby. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydrogen gas generation system that generates hydrogen gas by reforming a predetermined raw material, and a method for stopping operation of a fuel cell system using the hydrogen gas generation system.

  A fuel cell generates electricity by an electrochemical reaction between hydrogen gas and oxygen in the air. The hydrogen gas is generated by, for example, reforming a predetermined raw material. In general, natural gas, gasoline and other hydrocarbons, alcohols, ethers, aldehydes and the like are used as raw materials in this case. These raw materials generate reformed gas containing hydrogen and carbon monoxide by reforming. Since carbon monoxide is a harmful substance that poisons the electrode of the fuel cell, the reformed gas is usually supplied to the fuel cell after being subjected to a treatment that selectively oxidizes only carbon monoxide.

  When the operation of a fuel cell system including a unit that generates hydrogen gas by reforming and a fuel cell is stopped, it is necessary to discharge a combustible gas and a toxic gas from the system. This is because it is necessary to prevent harmful effects when these gases leak from the system. In addition, it is necessary to avoid adverse effects that occur in the system, such as poisoning of fuel cell electrodes. For this purpose, conventionally, when the operation of the fuel cell system is stopped, residual combustibles in the system are purged by supplying an inert gas.

  However, in the conventional system, it is necessary to store the inert gas for purging in a separate tank in advance. Since the inert gas is a gas that cannot be used for both reforming and power generation, storing the inert gas only when the operation is stopped is wasteful in terms of space and operation costs.

  On the other hand, no gas suitable for purging residual combustibles has been found. For example, if a gas containing oxygen is supplied, the combustible components in the residual combustible material may abnormally burn, and the heat may adversely affect the system. If a gas containing water vapor is supplied, there is a possibility that restarting may become difficult due to dew condensation after purging or the catalyst performance of the fuel cell may deteriorate. If condensation occurs, freezing may occur in a low temperature environment. Considering these adverse effects, there is a situation in which the inert gas must be used as the purge gas although there is waste as described above.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a technique for purging a residual combustible material without depending on an inert gas.

  In order to solve the above-mentioned problems, in the present invention, when a hydrogen gas generation system that reforms a predetermined raw material to generate hydrogen gas and stops its operation, the gas that is also used during the operation of the system is used. Purging was performed. However, various problems exemplified above were solved by controlling the supply method of these gases.

  That is, in the present invention, the operation of the hydrogen gas generation system is stopped through the air purge process. The air purge process is a process that supplies air into the system and forcibly discharges residual combustibles, and is executed when it is determined that environmental conditions that can avoid overheating due to the reaction between residual combustibles and oxygen are satisfied. Is done.

  The harmful effect of supplying air as the purge gas is that hydrogen, carbon monoxide, carbon, etc. in the residual combustible material react with oxygen and generate heat. The inventor of the present application has focused on the point that the adverse effects on the system caused by these heat generations occur in a high temperature environment. At low temperatures, the reaction with oxygen does not occur, or it generates only enough heat to have little effect on the system. For example, air can be used as the purge gas when the environmental conditions are below the temperature.

  When judging environmental conditions using temperature as a parameter, when the operation is stopped, no purging may be performed until the temperature is sufficiently lowered, or during this time, purging may be performed with an inert gas. According to the former, it is not necessary to store an inert gas. According to the latter, the usage-amount of an inert gas can be reduced significantly.

  The air purge process is performed when it is determined that the above-described environmental conditions are satisfied. This determination can be made, for example, by detecting the temperature in the system and based on the detection result. Further, the determination may be made based on the elapsed time after the operation is stopped, that is, the supply of the raw material is stopped.

  Environmental conditions also include conditions relating to the components of residual combustibles. If the residual combustible material contains only a small amount of the predetermined component that generates heat by reacting with oxygen, air purge can be performed even in a high temperature environment. In order to reduce the concentration of the predetermined component in the residual combustible material, it is effective to perform a purge using a gas not containing oxygen prior to the air purge.

  From this point of view, in the present invention, it is desirable to perform the water vapor purge step prior to the air purge step. The steam purge process is a process for supplying steam and forcibly discharging at least a part of the remaining combustible material. If it carries out like this, the predetermined component in a residual combustible material can be purged by a water vapor purge process. In addition, there is an advantage that the temperature drop of the system can be promoted. Since steam is also a gas used for reforming, the steam purge does not require any special additional configuration on the system. In the present invention, since the air purge is performed after the water vapor purge step, it is possible to avoid the adverse effects caused by condensation of water vapor and the adverse effects caused by freezing of water.

  In the case where a predetermined component in the residual combustible material is used as the environmental condition, the determination can be made based on, for example, the time of the steam purge process. What is necessary is just to obtain | require beforehand the time which can replace substantially the initial combustible material which started the purge with water vapor | steam.

  In the steam purge step, the steam is desirably supplied at a pressure lower than the saturated vapor pressure. By doing so, condensation in the water vapor purge process can be suppressed. Saturated vapor pressure varies with temperature and pressure in the system. In consideration of these fluctuation ranges, the water vapor may be supplied at a substantially constant pressure set sufficiently low, or the temperature and pressure are detected and supplied while controlling the pressure so as to satisfy the above conditions. It is good also as what to do. A known mechanism such as a pressure regulating valve can be applied to the pressure control. The target pressure at the time of pressure control may be stored in advance in relation to the temperature in the system, or may be calculated using a relational expression such as a Clausius-Clapeyron expression.

  When the steam purge step and the air purge step are used in combination, it is desirable to switch from the former to the latter based on at least one of temperature or pressure in the hydrogen gas generation system. In this way, switching at an appropriate timing can be realized. The switching condition is preferably set in consideration of, for example, the possibility of condensation of water vapor and the possibility of avoiding overheating due to reaction with oxygen. The former condition can be judged by whether or not the pressure of the supplied water vapor exceeds the saturated vapor pressure due to a temperature drop in the system. It is desirable to end the water vapor purge when the water vapor pressure is about to exceed the saturated vapor pressure at the latest. The latter condition can be judged by whether or not the temperature in the system has sufficiently decreased. It is desirable to start the air purge at least after the temperature in the system has dropped below a reference temperature that does not cause overheating.

  In this invention, it is good also as a process of decompressing the inside of a system after completion of a water vapor purge process and an air purge process. Hygroscopic materials such as ceramics may be used in the system. By the decompression step, evaporation of moisture absorbed by the moisture-absorbing material can be promoted, and adverse effects due to condensation in the system can be further suppressed.

  Regardless of whether or not the steam purge step is provided, it is desirable that the air purge step lowers the temperature of the supplied air as time passes. By doing so, the temperature of the system can be gradually lowered, and damage due to rapid cooling can be avoided.

  The temperature of the air may be continuously decreased or may be decreased stepwise. For example, when the hydrogen gas generation system is provided with an evaporation section that vaporizes the raw material for reforming, the air heated by the evaporation section is supplied, and then the operation of the evaporation section is stopped. By supplying the air heated by the residual heat, the temperature of the supplied air can be lowered stepwise.

  The present invention is applicable to various hydrogen gas generation systems using natural gas, gasoline and other hydrocarbons, alcohols, ethers, aldehydes and the like as raw materials. In particular, it is suitable for a hydrogen gas generation system using a hydrocarbon compound as a raw material. The reforming of the hydrocarbon compound is performed at a high temperature of 400 to 600 ° C., and generally carbon is likely to precipitate in the higher hydrocarbon compound. At such a high temperature, overheating tends to occur when carbon and oxygen come into contact with each other. By applying the present invention, purging can be performed using air while avoiding such overheating. In particular, it is preferable to perform a steam purge step and an air purge step.

  The present invention can be applied to the shutdown of various hydrogen gas generation systems regardless of the purpose of use of the generated hydrogen. The present invention is particularly useful for a fuel cell system including a combination of a hydrogen gas generation system and a fuel cell. If the operation is stopped by applying the present invention, not only the hydrogen gas generation system but also the purge in the fuel cell can be performed simultaneously. Therefore, there is an advantage that condensation in the fuel cell can be suppressed at the same time.

  The present invention can be configured in various modes in addition to the operation stop method described above. For example, you may comprise as a hydrogen gas production | generation system to which the operation stop mentioned above is applied. Such a hydrogen gas generation system includes a reforming unit that performs reforming, an air supply unit that supplies air to the reforming unit, and a control unit that controls the air supply unit. The control unit is configured to supply air into the reforming unit when it is determined that an environmental condition that can avoid overheating due to a reaction between the residual combustible material in the reforming unit and oxygen is satisfied when the operation is stopped. To control. The reforming section includes a unit that generates hydrogen gas from a raw material in a broad sense. Depending on the type of raw material, hydrogen gas is generated through a multi-stage chemical reaction such as a reforming reaction, a shift reaction, and a carbon monoxide oxidation reaction. These units are included in the reforming section.

  In addition to the above, the present invention can be configured in various modes such as a fuel cell system to which the above-described operation stop is applied, and a moving body in which the fuel cell system is mounted as an energy source. In each of these configurations, it is possible to consider various additional factors described above for the operation stop method. For example, when using air heated by the evaporation unit and air heated by the residual heat of the evaporation unit for purging, the air supply unit supplies air to the reforming unit via the evaporation unit. It is desirable to do.

The embodiment of the present invention will be described by dividing it into the following items.
A. System configuration:
B. Stop operation:
C. Variations:

A. System configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell system in an embodiment. The fuel cell system according to this embodiment includes a fuel cell 9 and a hydrogen gas generation system that generates hydrogen gas supplied thereto. The fuel cell 9 is a unit that generates electricity by an electrochemical reaction between hydrogen and oxygen. Although various types can be applied to the fuel cell 9, a solid polymer type is used in this embodiment.

  The hydrogen gas generation system reforms a predetermined raw material to generate hydrogen gas. The hydrogen gas means a gas rich in hydrogen and is not limited to pure hydrogen. In general, natural gas, gasoline and other hydrocarbons, alcohols, ethers, aldehydes, and the like are applicable as raw materials. In this embodiment, gasoline is used as a raw material. Gasoline produces hydrogen and carbon monoxide by a reforming reaction with steam and a partial oxidation reaction with air. These reactions take place in the next unit.

  The raw material is stored in the raw material tank 2, vaporized by the evaporator 3, and supplied to the reforming unit 4. The supply amount can be controlled by the valve 11. Steam used for reforming the raw material is generated by evaporating the water stored in the water tank 1 with the evaporator 3. The supply amount of water vapor can be controlled by the valve 10. The evaporator 3 is provided with a valve 12 for introducing air from the outside, heating it and supplying it to the reforming unit 4. The valve 12 is used in an operation stop process described later, and is closed when reforming is performed. The air used for reforming is introduced into the reforming unit 4 by the compressor 7 through a path not passing through the evaporator 3. In this path, switching valves 14 and 15 are provided. During operation, the switching valve 14 can be switched to the outside air introduction side, and the switching valve 15 can be switched to the reforming unit 4 side.

  The reforming unit 4 carries a catalyst for reforming the raw material. For supporting the catalyst, for example, a support such as ceramics can be used. When the vaporized raw material, water vapor, and air are supplied, hydrogen and carbon monoxide are generated. This reaction is usually performed at a high temperature of about 600 ° C. In the case of using gasoline or other hydrocarbon-based raw materials, it is known that carbon is likely to precipitate depending on the conditions during reforming, particularly for higher hydrocarbon compounds. It is desirable that the reforming conditions in the reforming unit 4 be appropriately selected so as to suppress the precipitation of carbon while promoting the reaction. In this embodiment, the steam reforming and the partial oxidation reaction are performed in parallel. However, it is possible to adopt a configuration in which only steam reforming is performed.

  The gas generated in the reforming unit 4 is supplied to the shift reaction unit 5. The shift reaction unit 5 carries a catalyst suitable for the shift reaction. The shift reaction refers to a reaction that generates carbon dioxide and hydrogen from carbon monoxide and water vapor, and the reaction is performed at about 300 ° C. Illustration of piping for supplying water vapor to the shift reaction unit 5 is omitted. In the case of using a raw material other than hydrocarbon, the shift reaction unit 5 can be omitted.

  The gas generated in the shift reaction unit 5 is supplied to the CO oxidation unit 6. The CO oxidation unit 6 carries a catalyst that selectively oxidizes carbon monoxide. The reformed hydrogen gas is supplied to the anode of the fuel cell 9 after carbon monoxide is oxidized to carbon dioxide by a selective oxidation reaction. A switching valve 13 is provided between the CO oxidation unit 6 and the fuel cell 9. The switching valve 13 is switched to the fuel cell 9 side during operation.

  The operation of the fuel cell system is controlled by the control unit 8. The control unit 8 is a microcomputer having a CPU and a memory inside. The control unit 8 controls the operation of the valves 10, 11, 12 in the system, the operation of the switching valves 13, 14, 15 and the operation of the compressor 7 and the evaporator 3. In order to perform the above control, various signals are input to the control unit 8. These signals include, for example, detection results from the pressure sensor 4p and the temperature sensor 4t provided in the reforming unit 4.

B. Stop operation:
FIG. 2 is a flowchart showing an operation stop process of the fuel cell system. The operation stop is realized by the control unit 8 controlling the valves 10, 11, 12 and the like according to this flowchart.

  FIG. 3 is an explanatory diagram showing the operation status of the system during the operation stop process. The supply state of the raw material and reforming air, the supply state of water vapor, the operation state of the evaporator 3, the supply state of heated air, and the operation state of the compressor 7 are illustrated.

  Hereinafter, the operation stop process will be described with reference to FIGS. 2 and 3. When the operation is stopped, the control unit 8 first stops the supply of the raw material and air to the reforming unit 4 (step S10 and time a in FIG. 3). That is, the valves 11 and 12 for supplying these are closed.

  The supply of steam to the reforming unit 4 is continued. Thereby, the water vapor purge in the system is performed (step S12). The steam purge is continued for a preset time t1. The duration t1 can be set in consideration of environmental conditions that allow the heated air purge to be described later to be started. The environmental conditions are conditions in which combustible components contained in residual combustible materials in the system, carbon deposited during reforming, etc. come into contact with oxygen in the air and abnormal combustion does not occur. More specifically, conditions under which the temperature in the system is sufficiently reduced, conditions under which combustible components and carbon are substantially exhausted from the system can be used. In this example, paying attention to the latter condition, the time for which the gas remaining in the system almost immediately after the start of the operation stop is substantially replaced with water vapor was obtained by experiments and used as the duration t1.

  When performing the steam purge, it is desirable to supply the steam at a pressure high enough to purge the remaining combustible material. On the other hand, in order to avoid condensation in the system, it is desirable that the water vapor is supplied at a pressure not exceeding the saturated vapor pressure. In this embodiment, in consideration of these points, the water vapor is supplied at a pressure slightly lower than the saturated vapor pressure. Since the saturated vapor pressure depends on the temperature in the system, the temperature of the reforming unit 4 is detected by the temperature sensor 4t, and the water vapor pressure is set based on the detected temperature. The pressure control is realized by controlling the opening degree of the valve 10 and the pressure regulating mechanism of the evaporator 3. Although the pressure may be controlled in an open loop, in this embodiment, feedback control based on the detection result of the pressure sensor 4p is applied. As the temperature in the system changes, the water vapor supply pressure also varies. In the present embodiment, only the temperature and pressure of the reforming unit 4 are detected, but the temperature and pressure of other units may be considered together. Needless to apply such control, the steam may be supplied at a constant pressure with a margin with respect to the lowest saturated steam pressure during the steam purge.

  When the time t1 elapses, the control unit 8 stops the steam purge and switches to the heated air purge (step S14 and times b and c in FIG. 3). In this embodiment, the switching between the two is performed gradually. You can switch instantly.

  The steam purge is stopped by closing the valve 10. The heated air purge is a purge realized by supplying air heated by the evaporator 3 to the reforming unit 4. Therefore, the control unit 8 keeps the operation of the evaporator 3, opens the valve 12, and takes air into the evaporator 3. The introduced air is heated by the evaporator 3 and supplied to the reforming unit 4. As a result, it is possible to achieve purging with air having a temperature substantially equal to or higher than that during steam purge. The heated air purge is continued for a preset time t2.

  The heated air purge corresponds to a process of removing moisture supplied in the water vapor purge process from the system together with the remaining hot air purge described later. Heated air is used for the purpose of promoting drying in the system and for avoiding condensation and damage to the system by preventing a rapid drop in temperature. The duration t2 may be set appropriately for each system from these viewpoints. In order to suppress energy consumption due to the operation of the evaporator 3, it is preferable that the duration t2 is short.

  When the time t2 has elapsed, the control unit 8 stops the heated air purge and switches to the remaining hot air purge (step S16 and time d in FIG. 3). The residual heat air purge is a purge using air whose temperature has been raised by the residual heat after the operation of the evaporator 3 is stopped. The residual heat purge is realized by the control unit 8 stopping the operation of the evaporator 3. As the temperature of the evaporator 3 decreases, the temperature of the remaining hot air also gradually decreases. As a result, it is possible to promote a decrease in the temperature of the entire system including the evaporator 3 together with the purge in the system. The remaining hot air purge is continued for a preset time t3.

  The preheated air purge step is a step of removing water in the system and lowering the temperature of the system. From these viewpoints, the duration time t3 may be appropriately set according to the system configuration. The duration t3 can be determined by the following method as an example together with the duration t2 described above. That is, the minimum value of the duration t3 is determined for the purpose of cooling the system, and the durations t2 and t3 are comprehensively determined within a range where the duration t3 does not fall below the minimum value. The durations t2 and t3 are set in consideration of both the shortening of the total time for shortening the purge time and the shortening of the duration t2 for suppressing the use energy.

  When the time t3 elapses, the control unit 8 stops the remaining hot air purge and performs a pressure reduction process in the system (step S18 and time e in FIG. 3). The stop of the remaining hot air purge is realized by closing the valve 12 for introducing air into the evaporator 3. The decompression process is performed using the compressor 7. The system can be depressurized by switching the switching valves 13 to 15 and operating the compressor 7 so that the gas is exhausted through the compressor 7. The removal of moisture absorbed by a hygroscopic material such as ceramics can be promoted by the reduced pressure. From this point of view, the target pressure at the time of depressurization may be appropriately set within a range in which moisture can be sufficiently removed. In this example, the pressure was reduced to a pressure state lower than the atmospheric pressure. When such pressure reduction is completed, the control unit 8 stops the operation of the compressor 7, switches the switching valves 13 to 15 in a direction that prevents the introduction of outside air, and the operation stop processing is completed (time f in FIG. 3). The decompression process is a process for removing water vapor more completely in addition to the heated air purge and the preheated air purge, and can be omitted. The pressure inside the system may be gradually reduced to the atmospheric pressure by gradually releasing the pressure.

  According to the operation stop method of the embodiment described above, an inert gas is not required for purging in the system. Since purging can be performed using gas required during operation, that is, water vapor and air, it is not necessary to provide a tank unique to shutdown. Therefore, the system can be reduced in size and the system can be simplified.

  Further, by removing moisture using air after the water vapor purge, it is possible to avoid problems caused by condensation in the system and problems caused by freezing of moisture.

C. Variations:
FIG. 4 is a flowchart of an operation stop process as a modification. In the embodiment, the case where the switching from the steam purge to the heated air purge is performed using the elapse of the duration t1 as a trigger is illustrated. In a modification, the case where both are switched based on the temperature conditions of the reforming unit 4 is illustrated.

  When the operation is stopped, the control unit 8 stops the supply of the raw material and air to the reforming unit 4 and performs steam purge (steps S20 and S22). In the modification, water vapor is supplied at a constant pressure. The steam purge is continued until the temperature Tr in the system falls below a preset reference temperature T1 (step S24). The setting of the steam supply pressure and the reference temperature T1 will be described later.

  When the temperature Tr in the system falls below the reference temperature T1, the control unit 8 stops the steam purge and performs the heated air purge (step S26). After performing the heated air purge for a certain time, the operation of the evaporator is stopped and the remaining hot air purge is performed (step S28). After the remaining hot air purge is performed for a certain time, a decompression process is performed (step S30). Since these processes are the same as those in the embodiment, detailed description thereof is omitted. As in the embodiment, the decompression process can be omitted.

  The reference temperature T1 corresponds to an environmental condition that can avoid the harmful effects of air purge. As described in the embodiment, it is desirable to suppress abnormal combustion between the components in the residual combustible material and the oxygen in the air during the air purge. The reference temperature T1 is set in a range in which such abnormal combustion can be suppressed. For example, it is said that abnormal combustion of precipitated carbon and oxygen occurs at a high temperature of about 400 ° C. or higher. Accordingly, the reference temperature T1 may be set to a temperature sufficiently lower than 400 ° C.

  The supply pressure of water vapor can be set in consideration of the reference temperature T1. FIG. 5 is an explanatory view showing a method for setting the supply pressure of water vapor. As described above, the supply pressure of water vapor is desirably set in a range lower than the saturated vapor pressure. As shown in the figure, the saturated vapor pressure decreases as the temperature decreases. If the water vapor pressure for purging is a constant value Ps, water vapor condensation occurs in a region where the saturated vapor pressure is lower than Ps, that is, in a low temperature region below the critical temperature Tsat. In order to avoid such condensation, the pressure Ps of the purge steam is set so that the critical temperature Tsat is sufficiently lower than the reference temperature T1. The margin ΔT between the critical temperatures Tsat and T1 can be set arbitrarily.

  Also by the processing of the modified example, purging that does not depend on the inert gas can be realized as in the embodiment. In addition, by switching from the water vapor purge to the air purge based on the temperature in the system, there is also an advantage that condensation during the purge process can be more reliably suppressed.

  In the embodiment and the modification, the case where the heated air purge and the remaining heat air purge are used together is exemplified, but only one of them may be used. Further, purging by outside air may be used.

  In the embodiment, the case where the steam purge and the air purge are used in combination is exemplified, but only the air purge may be performed. For example, the system may be cooled and the air purge may be started when the temperature is sufficiently lowered. Further, instead of the steam purge, purging with an inert gas may be performed. In this case, a tank for storing the inert gas is required, but the size can be reduced as compared with the conventional case.

  In the embodiments, application to a fuel cell system is illustrated, but the hydrogen gas consumption system is not limited to a fuel cell. In the embodiment, the case where the entire system is purged together is illustrated, but a configuration may be adopted in which purging is performed for each unit, such as the reforming unit 4 and the shift reaction unit 5.

From the above-described embodiments, the following application examples can be grasped.
Application Example 1 An operation stop method for stopping operation of a hydrogen gas generation system that reforms a predetermined raw material to generate hydrogen gas,
An operation stop method comprising a water vapor purge step of supplying water vapor into the hydrogen gas generation system and discharging at least a part of the residual combustible material in the stop processing of the hydrogen gas generation system.
[Application Example 2] The operation stop method according to Application Example 1,
An operation stop method in which the water vapor is supplied at a pressure lower than a saturated vapor pressure.
[Application Example 3] The operation stop method according to Application Example 1,
An operation stop method comprising an air purge step of supplying air into the hydrogen gas generation system and discharging the residual combustible material after the water vapor purge step.
[Application Example 4] The operation stop method according to Application Example 3,
An operation stop method for switching from the steam purge step to the air purge step based on at least one of temperature and pressure in the hydrogen gas generation system.
[Application Example 5] The operation stop method according to Application Example 3,
An operation stop method comprising a step of depressurizing the system after completion of the water vapor purge step and the air purge step.
[Application Example 6] The operation stop method according to Application Example 3,
The operation stop method which performs the said air purging process using low temperature air with progress of time.
[Application Example 7] The operation stop method according to Application Example 6,
The hydrogen gas generation system includes an evaporation unit that vaporizes the raw material for reforming,
The air purging step is an operation stopping method in which the air heated by the evaporation unit is supplied, and then the operation of the evaporation unit is stopped and the air heated by the remaining heat is supplied.
[Application Example 8] The operation stop method according to Application Example 1,
The operation stopping method, wherein the predetermined raw material is a hydrocarbon compound.
Application Example 9 An operation stop method for stopping operation of a fuel cell system including a hydrogen gas generation system that generates hydrogen gas by reforming a predetermined raw material, and a fuel cell that generates electric power using the generated hydrogen Because
In the hydrogen gas generation system and the fuel cell operation stop processing, an operation stop method comprising a water vapor purge step of supplying water vapor into the hydrogen gas generation system and discharging at least a part of the residual combustible material.
Application Example 10 A hydrogen gas generation system that generates hydrogen gas by reforming a predetermined raw material,
A reforming section for performing the reforming;
A steam supply section for supplying steam to the reforming section;
A hydrogen gas generation system comprising: a control unit that controls the water vapor supply unit so as to supply water vapor into the reforming unit in an operation stop process of the hydrogen gas generation system.

  Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that various configurations can be adopted without departing from the spirit of the present invention.

It is explanatory drawing which shows schematic structure of the fuel cell system in an Example. It is a flowchart which shows the operation stop process of a fuel cell system. It is explanatory drawing which shows the operation | movement condition of the system at the time of a driving | operation stop process. It is a flowchart of the operation stop process as a modification. It is explanatory drawing which shows the setting method of the supply pressure of water vapor | steam.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Water tank 2 ... Raw material tank 3 ... Evaporator 4 ... Reforming unit 4p ... Pressure sensor 4t ... Temperature sensor 5 ... Shift reaction unit 7 ... Compressor 8 ... Control unit 9 ... Fuel cell 10,11,12 ... Valve 13, 14, 15 ... Switching valve

Claims (10)

An operation stop method for stopping operation of a hydrogen gas generation system that reforms a predetermined raw material to generate hydrogen gas,
When it is determined that an environmental condition capable of avoiding overheating due to the reaction between the residual combustible material and oxygen in the hydrogen gas generation system is established, air is supplied into the hydrogen gas generation system to force the residual combustible material. An operation stop method including an air purge step for discharging. The operation stop method according to claim 1,
Regardless of the environmental conditions, an operation stop method including a water vapor purge step of supplying water vapor into the hydrogen gas generation system and forcibly discharging at least a part of the residual combustible material before supplying the air. The operation stop method according to claim 2,
An operation stop method in which the water vapor is supplied at a pressure lower than a saturated vapor pressure. The operation stop method according to claim 2,
An operation stop method for switching from the steam purge step to the air purge step based on at least one of temperature and pressure in the hydrogen gas generation system. The operation stop method according to claim 2,
An operation stop method comprising a step of depressurizing the system after completion of the water vapor purge step and the air purge step. The operation stop method according to claim 1,
The operation stop method which performs the said air purging process using low temperature air with progress of time. The operation stop method according to claim 6,
The hydrogen gas generation system includes an evaporation unit that vaporizes the raw material for reforming,
The air purging step is an operation stopping method in which the air heated by the evaporation unit is supplied, and then the operation of the evaporation unit is stopped and the air heated by the remaining heat is supplied. The operation stop method according to claim 1,
The operation stopping method, wherein the predetermined raw material is a hydrocarbon compound. An operation stop method for stopping operation of a fuel cell system comprising a hydrogen gas generation system that reforms a predetermined raw material to generate hydrogen gas, and a fuel cell that generates electric power using the generated hydrogen,
An air purge that supplies air and forcibly discharges the residual combustible material when it is determined that an environmental condition capable of avoiding overheating due to the reaction between the hydrogen gas generation system and the residual combustible material in the fuel cell and oxygen is established. An operation stop method comprising the steps. A hydrogen gas generation system for generating hydrogen gas by reforming a predetermined raw material,
A reforming section for performing the reforming;
An air supply unit for supplying air to the reforming unit;
The air supply unit is configured to supply air into the reforming unit when it is determined that an environmental condition capable of avoiding overheating due to a reaction between the residual combustible material in the reforming unit and oxygen is satisfied when the operation is stopped. A hydrogen gas generation system comprising a control unit for controlling.

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