JP2011256059A - Method for operating hydrogen generator and fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for operating a hydrogen generator and a fuel cell system that can efficiently prevent deposition of carbon and condensation of water at start-up.SOLUTION: The method for operating the hydrogen generator 100 includes: a first passage 21 where a material gas flows; a reformer for generating a hydrogen containing gas using the material gas supplied form the first passage; a CO reducer for reducing carbon monoxide in the hydrogen containing gas; a second passage 22 for returning the gas exhausted by the CO reducer to the first passage 21; and a combustor 2 for heating the reformer. A circulation operation for returning at least one part of the gas exhausted by the CO reducer to the first passage 21 through the second passage 22 is carried out while heating the reformer by the combustion operation of the combustor 2 and supplying the material gas to the reformer via the first passage 21 at the start-up.

Description

  The present invention relates to a hydrogen generator that generates a hydrogen-rich gas containing hydrogen and a method for operating a fuel cell system including the same, and more particularly to a hydrogen generator and a method for starting a fuel cell system.

  The fuel cell system is easily developed as a distributed power generation system that can easily construct a system for using thermal energy generated during power generation and can realize high energy use efficiency. The fuel cell system supplies fuel gas (hydrogen gas) and oxidant gas (air) from the outside to the fuel cell, and generates power by an electrochemical reaction between the supplied fuel gas and oxidant gas. The generated heat is recovered as hot water and stored in a hot water tank, and the hot water is effectively used for heat supply to the outside.

  A fuel cell system generally generates power using hydrogen. Since a hydrogen supply facility is not provided as a general infrastructure, a hydrogen generator is generally provided in the fuel cell. A hydrogen-containing gas for power generation is generated by a hydrogen generator using raw materials supplied from an existing infrastructure such as a gas pipe connected to a gas supply base or an LPG gas cylinder.

  The hydrogen generator is composed of a reformer and a CO reducer. The raw material and water are supplied to the reformer, and a steam reforming reaction occurs in the reforming catalyst in the reformer, and a reformed gas containing hydrogen is generated. Since carbon monoxide (hereinafter referred to as CO) contained in the reformed gas poisons the fuel cell, the CO in the reformed gas is reduced by the CO reducer. The CO reducer typically includes a shift catalyst and a CO selective oxidation catalyst. The shift catalyst reacts CO and steam in the reformed gas, and reduces CO to about 0.5 to 1% by a shift reaction. The CO selective oxidation catalyst selectively removes CO by reacting CO contained in the reformed gas that has passed through the shift catalyst with a small amount of air, and reduces CO to several ppm to several tens of ppm.

  By the way, in the start-up process of the hydrogen generator, when heating and heating the reformer and the CO reducer in the hydrogen generator, the raw material that has passed through the reformer and the CO reducer in the combustor that heats the reformer It has been proposed to burn. (For example, refer to Patent Document 1).

JP 2001-354401 A

  However, in the conventional hydrogen generator, the reformer is preferentially heated over the CO reducer in the temperature raising operation, so that a temperature difference is likely to occur between the reformer and the CO reducer. There was a problem.

  The present invention has been made in order to solve the above-described problems, and a hydrogen generation apparatus in which a temperature difference between a reformer and a CO reducer is reduced as compared with the prior art in a temperature rising operation at start-up, and An object of the present invention is to provide a method for operating a fuel cell system.

  In order to solve the above problems, an operation method of a hydrogen generator of the present invention includes a first path through which a source gas flows, a reformer that generates a hydrogen-containing gas using the source gas supplied from the first path, and A hydrogen generator comprising: a CO reducer for reducing carbon monoxide in the hydrogen-containing gas; a second path for returning the gas discharged from the CO reducer to the first path; and a combustor for heating the reformer An operation method of the apparatus, wherein at the time of start-up, the reformer is heated by the combustion operation of the combustor and the raw material gas is supplied to the reformer through the first path, and at least one of the gases discharged from the CO reducer. A circulation operation for returning the unit to the first path via the second path is executed.

  In such a configuration, even if the amount of the raw material gas flowing from the CO reducer into the combustor is equal to that of the conventional hydrogen generator, the flow rate of the raw material gas flowing through the CO reducer is higher than that of the conventional hydrogen generator. Therefore, the temperature rise of the CO reducer is promoted, and the temperature difference between the reformer and the CO reducer is reduced.

  According to the operation method of the hydrogen generator and the fuel cell system of the present invention, the temperature difference between the reformer and the CO reducer can be reduced in the temperature raising operation at the time of startup.

FIG. 1 is a block diagram showing an example of a schematic configuration of the hydrogen generator according to the first embodiment of the present invention. FIG. 2 is a block diagram showing an example of a schematic configuration of the hydrogen generator in the first embodiment of the present invention. FIG. 3 is a flowchart showing an example of an operation method of the hydrogen generator according to the first embodiment of the present invention. FIG. 4 is a flowchart showing an example of an operation method of the hydrogen generator according to Modification 1 of the first embodiment of the present invention. FIG. 5 is a flowchart showing an example of an operation method of the hydrogen generator according to Modification 2 of the first embodiment of the present invention. FIG. 6 is a block diagram showing an example of a schematic configuration of the hydrogen generator according to the second embodiment of the present invention. FIG. 7 is a flowchart showing an example of an operation method of the hydrogen generator according to the second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  An operation method of a hydrogen generator according to a first embodiment includes a first path through which a source gas flows, a reformer that generates a hydrogen-containing gas using a source gas supplied from the first path, and a hydrogen-containing gas A hydrogen generator comprising: a CO reducer that reduces carbon monoxide; a second path that returns gas discharged from the CO reducer to the first path; and a combustor that heats the reformer. At the time of start-up, the reformer is heated by the combustion operation of the combustor, the raw material gas is supplied to the reformer through the first path, and at least a part of the gas discharged from the CO reducer is supplied to the second path. A circulation operation to return to the first path via the is executed.

  In such a configuration, even if the amount of the raw material gas flowing from the CO reducer into the combustor is equal to that of the conventional hydrogen generator, the flow rate of the raw material gas flowing through the reformer and the CO reducer is the same as that of the conventional hydrogen generator. Since it increases more than a hydrogen generator, the temperature rise of a CO reducer is accelerated | stimulated and the temperature difference of a reformer and a CO reducer is reduced.

  The operation method of the hydrogen generator according to the second aspect is the operation method of the hydrogen generator according to the first aspect, comprising a hydrodesulfurizer for removing sulfur compounds contained in the raw material gas in the first path, The second path is configured to return the gas discharged from the CO reducer to the first path upstream of the hydrodesulfurizer.

  In such a configuration, the second path and the recycling path for supplying hydrogen to the hydrodesulfurizer are made common, and the cost is reduced.

  The operation method of the hydrogen generator according to the third embodiment is the operation method of the hydrogen generator according to the first embodiment, and at the time of startup, the start and stop of the combustion operation of the combustor is repeated, and at least the combustor The circulation operation is executed during the period when the combustion operation of the engine is stopped.

  In such a configuration, the temperature difference between the reformer and the CO reducer can be further reduced.

  The operation method of the hydrogen generator according to the fourth embodiment is the operation method of the hydrogen generator according to the first embodiment, and the temperature of the reformer is lower than the temperature at which carbon deposition occurs from the raw material at start-up. When the temperature exceeds the third temperature, the combustion operation of the combustor is stopped, and after the circulation operation is executed, the combustion operation of the combustor is started when the temperature of the reformer decreases.

  With this configuration, the temperature difference between the reformer and the CO reducer can be further reduced while suppressing carbon deposition in the reformer.

  The operation method of the hydrogen generator according to the fifth embodiment is the same as the operation method of the hydrogen generator according to the first embodiment, comprising a steam supply device for supplying steam to the reformer, When the temperature is equal to or higher than a first temperature that is a temperature at which water is not condensed in the reformer, and the temperature of the CO reducer is equal to or higher than a second temperature that is a temperature at which water is not condensed within the CO reducer, Steam is supplied from the steam supply unit to the reformer while the combustion operation of the combustor is continued.

  In such a configuration, when the supply of water vapor to the reformer is started, water condensation in the reformer and the CO reducer can be suppressed.

  The operation method of the hydrogen generator according to the sixth embodiment is the operation method of the hydrogen generator according to the third embodiment, and passes through the second path when the combustion operation of the combustor is stopped at startup. The flow rate of the raw material gas to be made is larger than the flow rate of the raw material gas passing through the second path when the combustion operation of the combustor is being performed.

In such a configuration, the reformer and the CO reducer are compared with the case where the flow rate of the raw material gas passing through the second path when the combustion operation of the combustor is not made larger than the flow rate of the raw material gas passing through the second path before stopping. The temperature difference between and can be reduced more quickly.
The operation method of the hydrogen generator according to the seventh aspect is the same as the operation method of the hydrogen generator according to the first or sixth aspect, wherein the gas discharged from the CO reducer and not flowing into the second path is guided to the combustor. 3 flow paths are provided in the second path, and when the temperature of the reformer becomes equal to or higher than the third temperature, which is lower than the temperature at which carbon deposition occurs from the raw material, at the start-up, Thus, the ratio of the flow rate of the gas flowing into the second path to the flow rate of the gas discharged from the CO reducer is increased.

  In such a configuration, the ratio of the flow rate of the gas flowing into the second path is not increased, and the reformer and the CO reducer are controlled while suppressing carbon deposition in the reformer, compared to the case where the circulation operation is performed. The temperature difference can be further reduced.

  Note that the supply amount of the raw material gas to the reformer does not need to be constant before and after increasing the flow rate ratio. If the inflow amount of the raw material gas to the combustor is reduced, the supply amount of the raw material gas to the reformer may be arbitrarily changed before and after the ratio of the flow rates is increased.

  The operation method of the hydrogen generator according to the eighth embodiment is the operation method of the hydrogen generator according to the seventh embodiment, and corresponds to the flow rate of the gas discharged from the CO reducer by the flow rate regulator at startup. After the ratio of the flow rate of the gas flowing into the second path is increased, when the temperature of the reformer decreases, the ratio is decreased by the flow rate regulator.

  In such a configuration, even if the temperature of the reformer decreases after increasing the flow rate ratio, the temperature increase of the reformer and the CO remover can be promoted as compared with the case where the state continues.

  An operation method of a fuel cell system according to a first embodiment includes a first path through which a source gas flows, a reformer that generates a hydrogen-containing gas using the source gas supplied from the first path, and a hydrogen-containing gas CO reducer for reducing carbon monoxide, second path for returning gas discharged from the CO reducer to the first path, combustor for heating the reformer, and hydrogen content discharged from the CO reducer An operation method of a fuel cell system including a fuel cell that generates electricity using gas, and at the time of start-up, heats the reformer by a combustion operation of the combustor and supplies a raw material gas to the reformer through a first path Then, a circulation operation for returning at least a part of the gas discharged from the CO reducer to the first path through the second path is executed.

  In such a configuration, even if the amount of raw material gas flowing from the CO reducer into the combustor is equal to that of the conventional fuel cell system, the flow rate of the raw material gas flowing through the CO reducer is higher than that of the conventional fuel cell system. Therefore, the temperature rise of the CO reducer is promoted, and the temperature difference between the reformer and the CO reducer is reduced.

(First embodiment)
[Device configuration]
FIG. 1 is a block diagram showing an example of a schematic configuration of the hydrogen generator according to the first embodiment of the present invention. FIG. 2 is a block diagram showing an example of a schematic configuration of the hydrogen generator in the first embodiment of the present invention. Hereinafter, the device configuration of the hydrogen generator according to the first embodiment will be described with reference to FIGS. 1 and 2.

As shown in FIG. 1, the hydrogen generator 100 of the present embodiment uses a raw material gas (a gas containing hydrocarbons such as methane gas and propane gas) and water and a hydrogen-containing gas (a gas containing H ₂ gas). ), A first path 21 through which the raw material supplied to the hydrogen generator 1 flows, a combustor 2 that heats the hydrogen generator 1, and a booster pump 3 provided in the first path 21 A flame rod 4 for detecting the combustion state of the combustor 2, a combustion fan 5 for supplying combustion air to the combustor 2, and a gas discharged from the hydrogen generator 1 in the upstream side of the booster pump 3. A second path 22 that returns to the first path 21; a third path 23 that branches from the second path 22 and supplies the gas discharged from the hydrogen generator 1 to the combustor 2; and a hydrogen that branches from the third path 23 and hydrogen. Hydrogen discharged from the generator 1 And a controller 30. The controller 30 includes a fourth path 24 that supplies the fuel device 150, a flue gas path 16 through which the flue gas discharged from the combustor 2 flows.

  In the first path 21, the first valve 11 is provided on the upstream side from the junction of the first path 21 and the second path 22. The second path 22 is provided with a second valve between the point where the third path 23 branches from the second path 22 and the junction of the first path 21 and the second path 22. The third path 23 is provided with a third valve downstream from the point where the fourth path 24 branches from the third path 23. A fourth valve 14 is provided in the fourth path 24. The 1st valve 11, the 2nd valve 12, the 3rd valve 13, and the 4th valve 14 consist of an electromagnetic on-off valve, for example.

As shown in FIG. 2, the hydrogen generator 1 of this embodiment includes a hydrodesulfurizer 43 that removes sulfur components contained in a raw material gas using hydrogen (H ₂ gas), and reforming from the raw material gas and steam. A reformer 41 that generates a hydrogen-containing gas by reaction, a CO reducer 42 that reduces the concentration of CO contained in the hydrogen-containing gas discharged from the reformer 41, and a temperature that detects the temperature of the reformer 41. A first temperature detector 44 and a second temperature detector 45 that detects the temperature of the CO reducer 42 are provided. The first temperature detector 44 and the second temperature detector 45 include, for example, a thermocouple. The CO reducer 42 is constituted by at least one of a transformer and a CO remover. The transformer is a device that reduces the CO concentration of the hydrogen-containing gas by an aqueous shift reaction, and the CO remover is a device that reduces the CO concentration of the hydrogen-containing gas by at least one of an oxidation reaction and a methanation reaction. .

  The hydrodesulfurizer 43 reacts a sulfur-containing compound, which is an odor component in the raw material gas, with hydrogen to form hydrogen sulfide, which is removed by adsorption. As the hydrogen supplied to the hydrodesulfurizer 43, a hydrogen-containing gas discharged from the CO reducer 42 can be used. In addition, when hydrogen remains in the gas discharged | emitted from the hydrogen utilization apparatus 150, this gas can also be used as the hydrogen source of the hydrodesulfurizer 43.

  The hydrogen generator 100 includes a water supply path 17, a water supply pump 6 provided in the water supply path 17, and a water evaporator 7 provided in the water supply path 17 on the downstream side of the water supply pump. Water vapor is supplied to the reformer 41 through the water supply path 17 by the water supply pump 6 and the water evaporator 7. That is, the water vapor supply device in this embodiment includes a water supply pump 6 and a water evaporator 7. Heat is supplied from the combustor 2 to the water evaporator 7.

  The controller 30 includes, for example, a CPU, a memory, and a timer, and includes a booster pump 3, a frame rod 4, a combustion fan 5, a water supply pump 6, a first valve 11, a second valve 12, and a second valve. The three valves 13, the fourth valve 14, the first temperature detector 44, and the second temperature detector 45 are communicably connected.

  The reformer 41 is provided with a reforming catalyst (not shown). For example, a Ru catalyst is preferably used as the reforming catalyst. The CO reducer 42 is provided with a CO reduction catalyst (not shown). In the case where the CO reduction catalyst is a shift catalyst filled in the shift converter, for example, a copper zinc catalyst is preferably used. When the CO reduction catalyst is an oxidation catalyst filled in the CO remover, Pt, Ru, or the like is preferably used. When the CO reduction catalyst is a methanation catalyst, a Ru catalyst is preferably used. The hydrodesulfurizer 43 is provided with a hydrodesulfurization catalyst (not shown). As the hydrodesulfurization catalyst, for example, a copper zinc catalyst is preferably used. However, the type of catalyst is not limited to the above. Other noble metal catalysts and nickel catalysts are used as reforming catalysts, other noble metal catalysts and iron catalysts are used as CO reduction catalysts, and zinc oxide is used as a hydrodesulfurization catalyst. The catalyst and the Mo-based catalyst may be used alone or in combination of a plurality of catalysts.

  In the hydrogen generator of this embodiment, a hydrodesulfurizer is provided as shown in FIG. 2, but a hydrodesulfurizer is not provided, and a room temperature that physically adsorbs sulfur compounds in the raw material gas. You may employ | adopt the form which provides an adsorption desulfurizer. In this case, the second path 22 may be connected to either the first path 21 upstream or downstream of the room temperature desulfurizer.

[Operation]
FIG. 3 is a flowchart showing an example of an operation method of the hydrogen generator according to the first embodiment of the present invention. Hereinafter, the operation method of the hydrogen generator according to the present embodiment will be described with reference to FIG. In this embodiment, the operation method of FIG. 3 is executed by the controller 30 (the same applies to FIGS. 4, 5 and 7).

  When starting is started (start), combustion in the combustor 2 is started (step S101). At this time, the fourth valve 14 and the second valve 12 are closed, but the first valve 11 and the third valve are opened. The operation of the booster pump 3 is started, and the raw material gas is supplied to the reformer 41. The raw material gas that has passed through the reformer 41 is supplied to the combustor 2 through the CO reducer 42 and the third path 23. At the same time, the operation of the combustion fan 5 is started, and combustion air is supplied to the combustor 2. In the combustor 2, an ignition operation is performed by an ignition electrode (not shown), and the raw material gas is combusted using combustion air. The reformer 41 is heated by the combustion heat supplied from the combustor 2. The CO reducer 42 is heated by the gas discharged from the reformer 41.

  Thereafter, the second valve 12 is opened (step S102), and part of the raw material gas discharged from the CO reducer 42 passes through the second path 22 to the first path 21 upstream of the hydrodesulfurizer 43. Return (circulation). Thereby, since a gas having a flow rate larger than the supply amount of the raw material gas supplied from the raw material gas supply source flows through the hydrogen generator 1, the propagation of heat from the reformer 41 to the CO reducer 42 is promoted. . Thereby, compared with the conventional hydrogen generator, the temperature difference between the reformer 41 and the CO reducer 42 is reduced.

  Thereafter, it is determined whether or not the temperature detected by the first temperature detector 44 (the temperature of the reformer 41) is equal to or higher than the first temperature T1 (step S103A). The first temperature T1 is a temperature set so that water does not condense inside the reformer 41, and may be, for example, 150 ° C. If the determination result is No, the circulation operation is continued. The first temperature T1 is more preferably a temperature at which carbon deposition does not occur from the raw material gas in the reformer 41.

  When the determination result in step S103A is Yes, the operation of the water supply pump 6 is started (step S104), steam is generated in the water evaporator 7, and steam is supplied to the reformer 41. In the hydrogen generator of the present embodiment, the temperature difference between the reformer and the CO reducer is reduced by the above-described circulation operation, so that the amount of water vapor condensed in the CO reducer is reduced as compared with the conventional hydrogen generator. The deterioration of the CO reduction catalyst is suppressed.

  This completes the startup operation (end). The fourth valve 24 is opened when the composition and temperature of the hydrogen-containing gas generated by the hydrogen generator 1 reach a composition and temperature suitable for supply to the hydrogen utilization device 150 after the supply of the water vapor is started. Then, the hydrogen-containing gas is supplied to the hydrogen utilization device 150.

  Note that the hydrogen generator of the present embodiment does not include a heater for heating the CO reducer, but in order to further reduce the amount of water condensation in the CO reducer, a heater such as an electric heater is provided, and at least Before starting the supply of water vapor to the reformer 41, a form of heating the CO reducer may be employed.

[Modification 1]
In this modification, at the time of start-up, the temperature of not only the reformer but also the CO reducer is confirmed by the temperature detector, and supply of water vapor to the reformer is started.

  FIG. 4 is a flowchart showing an example of an operation method of the hydrogen generator according to Modification 1 of the first embodiment of the present invention. Hereinafter, the operation method of the hydrogen generator according to Modification 1 will be described with reference to FIG. Since steps other than step 103A are the same as those of the hydrogen generator of Embodiment 1, the description thereof is omitted.

  During the temperature raising operation of the reformer 41 and the CO reducer 42, the temperature detected by the first temperature detector 44 (the temperature of the reformer 41) is equal to or higher than the first temperature T1 after step S102. In addition, it is determined whether or not the temperature detected by the second temperature detector 45 (the temperature of the CO reducer 42) is equal to or higher than the second temperature T2 (step S103B). The first temperature T1 is a temperature set so that water does not condense inside the reformer 41, and may be, for example, 150 ° C. The second temperature T2 is a temperature set so that water does not condense inside the CO reducer 42, and may be set to 150 ° C., for example. If the determination result is No, the circulation operation is continued.

  When the determination result in step S103B is Yes, the operation of the water supply pump 6 is started (step S104), water vapor is generated in the water evaporator 7, and water vapor is supplied to the reformer 41. Thereby, even if water vapor is supplied to the reformer 41, the possibility of water condensing inside the reformer 41 and the CO reducer 42 is reduced.

  By the circulation operation, the temperature difference between the reformer and the CO reducer is reduced. When the temperature inside the reformer and the CO reducer reaches a temperature at which water does not condense, there is a possibility that the interior of the reformer is at a temperature at which carbon derived from the raw material does not precipitate. It is higher and preferable. Such a configuration is particularly preferable when the reforming catalyst is a catalyst that starts carbon deposition at a relatively low temperature of about 300 ° C., such as a Ni catalyst.

  This completes the startup operation (end). After the start of the supply of the water vapor, the fourth valve 24 is opened at a stage where the composition or temperature of the hydrogen-containing gas generated by the hydrogen generator 1 has reached a composition or temperature suitable for supply to the hydrogen utilization device 150, A hydrogen-containing gas is supplied to the hydrogen utilization device 150.

[Modification 2]
This modification is characterized in that at the time of start-up, the start and stop of the combustion operation of the combustor are repeated, and the circulation operation is executed at least during the period when the combustion operation of the combustor is stopped. As a specific example, at the time of start-up, when the temperature of the reformer becomes equal to or higher than a third temperature lower than the temperature at which carbon deposition occurs from the raw material, the combustion operation of the combustor is stopped and the circulation operation is executed. . The combustion operation of the combustor may be started when the temperature of the reformer decreases due to the circulation operation performed while the combustion operation of the combustor is stopped.

  FIG. 5 is a flowchart showing an example of an operation method of the hydrogen generator according to Modification 2 of the first embodiment of the present invention. Hereinafter, the operation method of the hydrogen generator according to Modification 2 will be described with reference to FIG.

  When starting is started (start), combustion in the combustor 2 is started (step S201), and the second valve 12 is opened (step S202). Since the above steps are the same as steps S101 and S102 of FIG. 3, detailed description thereof is omitted.

  Thereafter, the temperature detected by the first temperature detector 44 (the temperature of the reformer 41) is equal to or higher than the third temperature T3 and the temperature detected by the second temperature detector 45 (the temperature of the CO reducer 42). It is determined whether or not the temperature is lower than the second temperature T2 (step S203). The third temperature T3 is a temperature set so that carbon contained in the raw material gas does not precipitate inside the reformer 41. For example, when the reforming catalyst is a Ru catalyst, the temperature at which carbon deposition starts is 500 ° C., so the third temperature T3 is set to 300 ° C. as a temperature lower than that temperature. The third temperature T3 is set to a temperature higher than the first temperature T1.

  If the determination result in step S203 is Yes, carbon may be deposited in the reformer 41 if the temperature raising operation is continued without reducing the combustion amount of the combustor. Although it is conceivable to start supplying steam to the reformer 41 in order to prevent carbon deposition, at this time, the temperature of the CO reducer 42 is low, and water vapor condenses inside the CO reducer 42 to reduce CO. The catalyst may deteriorate. Therefore, combustion in the combustor 2 is stopped, and then, the circulation operation started in step S202 is continued and executed for a predetermined time (step S204). In order to stop the combustion, the operations of the booster pump 3 and the combustion fan 5 are stopped.

  The execution time of the circulation operation in the state where the combustion is stopped in step S204 is appropriately set with the goal of lowering the temperature of the reformer 41. What is the execution time of the circular operation? The controller 30 may measure using a timer. The temperature of the reformer 41 may be directly detected by, for example, the first temperature detector 44, and the circulation operation may be executed until the detected temperature reaches a predetermined temperature (for example, 250 ° C.).

  When step S204 ends, the temperature detected by the first temperature detector 44 (the temperature of the reformer 41) is equal to or higher than the first temperature T1, and the temperature detected by the second temperature detector 45 (the CO reducer 42). Is determined to be equal to or higher than the second temperature T2 (step S205A).

  If the determination result in step S205A is No, the temperature of the reformer 41 and / or the CO reducer 42 is low, and if steam is supplied as it is, water may condense and the catalyst may deteriorate. Therefore, the process returns to step S201 again, the combustion in the combustor 2 is restarted, the second valve is opened in step S202, and the circulation operation is executed.

  When the determination result in step S203 is No, the temperature detected by the first temperature detector 44 (the temperature of the reformer 41) is equal to or higher than the first temperature T1, and the temperature detected by the second temperature detector 45 ( It is determined whether or not the temperature of the CO reducer 42 is equal to or higher than the second temperature T2 (step S205B).

  When the determination result in step S205B is No, the temperature of the reformer 41 and / or the CO reducer 42 is low, and if steam is supplied as it is, water may condense and the catalyst may deteriorate. Therefore, the process returns to step S203 while the combustion in the combustor 2 is continued, and the heating of the reformer 41 and the CO reducer 42 is continued.

  When the determination result in step S205B is Yes, the temperatures of the reformer 41 and the CO reducer 42 are sufficiently high, and even if steam is supplied, there is a low possibility that water will condense and the catalyst will deteriorate. Therefore, the operation of the water supply pump 6 is started in a state where the combustion operation of the combustor 2 is continued (step S206), steam is generated in the water evaporator 7, and the steam is supplied to the reformer 41.

  This completes the startup operation (end). After the start of the supply of the water vapor, the fourth valve 24 is opened at a stage where the composition or temperature of the hydrogen-containing gas generated by the hydrogen generator 1 has reached a composition or temperature suitable for supply to the hydrogen utilization device 150, A hydrogen-containing gas is supplied to the hydrogen utilization device 150. The temperature of the reformer 41 or the reforming catalyst during the steady operation is about 600 to 700 ° C.

  In the hydrogen generator of this modification, the combustor 2 is configured to perform the circulation operation in both the period during which the combustion operation is performed and stopped, but the combustion operation of the combustor 2 is stopped. A mode in which the above-described circulation operation is executed only during a certain period may be adopted. What is necessary is just to perform the said circulation operation in the period which has stopped the combustion operation of the combustor 2 at least.

(Second Embodiment)
In the hydrogen generator of the second embodiment, at the time of startup, the flow rate of the raw material gas that passes through the second path when the combustion operation of the combustor is stopped, and the second path when the combustion operation of the combustor is being performed It is characterized by being larger than the flow rate of the raw material gas passing through. As a specific example, when the flow rate regulator is provided in the second path, and the temperature of the reformer becomes equal to or higher than a third temperature that is lower than the temperature at which carbon deposition occurs from the raw material at startup, the flow rate regulator Thus, the ratio of the flow rate of the gas flowing into the second path with respect to the flow rate of the gas discharged from the CO reducer is increased. In the hydrogen generator of the present embodiment, after the ratio of the flow rate of the gas flowing into the second path is increased as described above, the ratio may be decreased by the flow rate regulator when the temperature of the reformer decreases. .

[Device configuration]
FIG. 6 is a block diagram showing an example of a schematic configuration of the hydrogen generator according to the second embodiment of the present invention. The hydrogen generator 200 of this embodiment is obtained by replacing the second valve 12 with a flow rate adjusting valve 15 in the hydrogen generator 100 of the first embodiment, and other components are common. Therefore, the same name and code | symbol are attached | subjected to the component which is common between 1st Embodiment and 2nd Embodiment, and description is abbreviate | omitted.

  The flow rate adjustment valve 15 is communicably connected to the controller 30, and adjusts the flow rate of the gas flowing through the second path 22 by changing the opening degree based on the control of the controller 30. The flow rate adjustment valve 15 is composed of, for example, a variable orifice valve.

[Operation]
FIG. 7 is a flowchart showing an example of an operation method of the hydrogen generator according to the second embodiment of the present invention. Hereinafter, the operation method of the hydrogen generator according to the present embodiment will be described with reference to FIG.

  When starting is started (start), combustion in the combustor 2 is started (step S301). Since step S301 is the same as step S101 in FIG. 3, detailed description thereof is omitted.

  Thereafter, the opening degree of the flow rate adjusting valve 15 is set to 30% (step S302). Part of the source gas discharged from the CO reducer 42 returns to the first path 21 upstream of the hydrodesulfurizer 43 through the second path 22 (circulation operation). Thereby, a gas having a flow rate larger than the supply amount of the source gas supplied from the source gas supply source flows through the hydrogen generator 1, and the temperature difference between the reformer 41 and the CO reducer 42 is reduced. The temperature rise of the CO reducer 42 is also accelerated and the startup time is shortened.

  Thereafter, the temperature detected by the first temperature detector 44 (the temperature of the reformer 41) is equal to or higher than the third temperature T3 and the temperature detected by the second temperature detector 45 (the temperature of the CO reducer 42). It is determined whether or not the temperature is lower than the second temperature T2 (step S303). Since step S303 is the same as step S203, detailed description thereof is omitted.

  When the determination result in step S303 is Yes, carbon may be precipitated in the reformer 41. Although it is conceivable to supply steam to the reformer 41 in order to prevent carbon deposition, at this time, the temperature of the CO reducer 42 is low, the steam is condensed inside the CO reducer 42, and the CO reducing catalyst is There is a possibility of deterioration. Therefore, combustion in the combustor 2 is stopped, the opening degree of the flow rate adjusting valve 15 is set to 100%, and the circulation operation started in step S302 is continued and executed for a predetermined time (step S304). In order to stop the combustion, the third valve 13 is closed. The purpose of this step is to stop the temperature rise of the reformer 41 and lower the temperature of the reformer 41, but the rate of temperature reduction may be arbitrary. That is, before and after this step, the flow rate of the raw material gas supplied to the reformer 41 does not need to be constant, and may be arbitrarily changed. However, it is more preferable to control the booster pump 3 so as to increase the flow rate of the raw material gas supplied to the reformer 41 for the purpose of further promoting the temperature drop of the reformer 41.

  By changing the opening degree of the flow rate adjusting valve 15 from 30% to 100% in step S304, the ratio of the flow rate of the gas flowing into the second path to the flow rate of the gas discharged from the CO reducer increases. The execution time of the circulation operation in a state where the combustion is stopped and the opening degree of the flow rate adjustment valve 15 is changed to 100% is appropriately set with the goal of reducing the temperature of the reformer 41. What is the execution time of the circular operation The controller 30 may measure using a timer. The temperature of the reformer 41 may be directly detected by, for example, the first temperature detector 44, and the circulation operation may be executed until the detected temperature reaches a predetermined temperature (for example, 250 ° C.).

  When step S304 ends, the temperature detected by the first temperature detector 44 (the temperature of the reformer 41) is equal to or higher than the first temperature T1, and the temperature detected by the second temperature detector 45 (the CO reducer 42). Is determined to be equal to or higher than the second temperature T2 (step S305A).

  If the determination result in step S305A is No, the temperature of the reformer 41 and / or the CO reducer 42 is low, and if steam is supplied as it is, water may condense and the catalyst may deteriorate. Therefore, the process returns to step S301 again, and combustion in the combustor 2 is resumed. At step S302, the opening degree of the flow rate adjustment valve 15 is returned to 30%, and the circulation operation is executed. Thereby, the ratio of the flow rate of the gas flowing into the second path with respect to the flow rate of the gas discharged from the CO reducer decreases.

  When the determination result in step S303 is No, the temperature detected by the first temperature detector 44 (the temperature of the reformer 41) is equal to or higher than the first temperature T1, and the temperature detected by the second temperature detector 45 ( It is determined whether or not the temperature of the CO reducer 42 is equal to or higher than the second temperature T2 (step S305B).

  If the determination result in step S305B is No, the temperature of the reformer 41 and / or the CO reducer 42 is low, and if steam is supplied as it is, water may condense and the catalyst may deteriorate. Therefore, it returns to step S303 in the state where combustion in the combustor 2 is continued, and heating of the reformer 41 and the CO reducer 42 is continued.

  When the determination result in step S305B is Yes, the temperatures of the reformer 41 and the CO reducer 42 are sufficiently high, and there is a low possibility that the water will condense and the catalyst will deteriorate even if steam is supplied. Accordingly, the operation of the water supply pump 6 is started in a state where the combustion operation of the combustor 2 is continued (step S306), steam is generated in the water evaporator 7, and the steam is supplied to the reformer 41.

  This completes the startup operation (end). After the start of the supply of the water vapor, the fourth valve 24 is opened at a stage where the composition or temperature of the hydrogen-containing gas generated by the hydrogen generator 1 has reached a composition or temperature suitable for supply to the hydrogen utilization device 150, A hydrogen-containing gas is supplied to the hydrogen utilization device 150.

[Modification]
Unlike the hydrogen generator of the second embodiment, when the temperature of the reformer rises at the time of startup, the hydrogen generator of the present modification flows into the second path side while continuing the combustion operation of the combustor. The ratio of the amount of source gas to be increased is increased, and the amount of source gas flowing into the combustor is reduced. Specifically, in step S304 of the flow shown in FIG. 7, the third valve 13 is kept open and the operation of the combustion fan 5 is continued so that the combustion operation of the combustor 2 is not stopped. In this modification as well, the amount of source gas supplied to the reformer 41 does not have to be constant before and after increasing the ratio of the flow rates of source gas flowing into the second flow path. If the inflow amount of the raw material gas to the combustor is reduced, the supply amount of the raw material gas to the reformer may be arbitrarily changed before and after the ratio of the flow rates is increased.

[Modifications to the first embodiment, the second embodiment, and modifications of these embodiments]
This modification constitutes a fuel cell system by providing a fuel cell that generates electricity using hydrogen-containing gas discharged from a CO reducer as a hydrogen-using device in addition to the hydrogen generator of the second embodiment. It is. The fuel cell system of the present modification can be configured in the same manner as in FIGS. 1 and 2 or in FIGS. 6 and 2 except that the hydrogen using device 150 is a fuel cell. Therefore, about the common component, the same name and code | symbol are attached | subjected and description is abbreviate | omitted.

  Since the operation method of the fuel cell system in this modification can be the same as that of FIG. 3, FIG. 4, FIG. 5, or FIG.

  From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  The operation method of the hydrogen generator and the fuel cell system of the present invention can reduce the temperature difference between the reformer and the CO reducer in the temperature rising operation at the time of start-up. It is useful as a driving method.

DESCRIPTION OF SYMBOLS 1 Hydrogen generator 2 Combustor 3 Booster pump 4 Flame rod 5 Combustion fan 6 Water supply pump 7 Water evaporator 11 1st valve 12 2nd valve 13 3rd valve 14 4th valve 15 Flow control valve 17 Water supply path 21 1st 1 path 22 2nd path 23 3rd path 24 4th path 30 controller 41 reformer 42 CO reducer 43 hydrodesulfurizer 44 first temperature detector 45 second temperature detector 100, 200 hydrogen generator 150 hydrogen Equipment used

Claims (9)

A first path through which the source gas flows;
A reformer that generates a hydrogen-containing gas using the source gas supplied from the first path;
A CO reducer for reducing carbon monoxide in the hydrogen-containing gas;
A second path for returning the gas discharged from the CO reducer to the first path;
A combustor for heating the reformer, and a method of operating a hydrogen generator comprising:
At the time of start-up, the reformer is heated by the combustion operation of the combustor, the raw material gas is supplied to the reformer through the first path, and at least a part of the gas discharged from the CO reducer is supplied. An operation method for a hydrogen generator, wherein a circulation operation for returning to the first path through the second path is executed. The first path includes a hydrodesulfurizer that removes sulfur compounds contained in the source gas,
The operation of the hydrogen generator according to claim 1, wherein the second path is configured to return the gas discharged from the CO reducer to the first path upstream of the hydrodesulfurizer. Method.   The operation method of the hydrogen generator according to claim 1, wherein at the time of start-up, the combustion operation of the combustor is repeatedly started and stopped, and the circulation operation is executed at least during a period when the combustion operation of the combustor is stopped. .   At the time of start-up, when the temperature of the reformer reaches a third temperature that is lower than the temperature at which carbon deposition occurs from the raw material, the combustion operation of the combustor is stopped and the circulation operation is performed. The operation method of the hydrogen generator according to claim 3, wherein the combustion operation of the combustor is started when the temperature decreases. A water vapor supply device for supplying water vapor to the reformer;
At the time of start-up, the temperature of the reformer is equal to or higher than a first temperature that is a temperature at which water does not condense in the reformer, and the temperature of the CO reducer is reduced by water in the CO reducer. The method for operating a hydrogen generator according to claim 1, wherein when the temperature is not less than a second temperature that is not condensed, steam is supplied from the steam supplier to the reformer while the combustion operation of the combustor is continued.   When starting, the flow rate of the raw material gas that passes through the second path when the combustion operation of the combustor is stopped, and the flow rate of the raw material gas that passes through the second path when the combustion operation of the combustor is being performed. The method for operating the hydrogen generator according to claim 3, wherein the method is larger. A third path for guiding the gas discharged from the CO reducer and not flowing into the second path to the combustor, and a flow regulator is provided in the second path;
At the time of start-up, when the temperature of the reformer becomes equal to or higher than a third temperature that is lower than the temperature at which carbon deposition occurs from the raw material, the flow regulator adjusts the flow rate of the gas discharged from the CO reducer. The operation method of the hydrogen generator according to claim 1 or 6, wherein a ratio of a flow rate of the gas flowing into the second path is increased.   At the time of start-up, after the ratio of the flow rate of the gas flowing into the second path to the flow rate of the gas discharged from the CO reducer is increased by the flow rate regulator, The operation method of the hydrogen generator according to claim 7, wherein the ratio is decreased by a flow rate regulator. A first path through which the source gas flows;
A reformer that generates a hydrogen-containing gas using the source gas supplied from the first path;
A CO reducer for reducing carbon monoxide in the hydrogen-containing gas;
A second path for returning the gas discharged from the CO reducer to the first path;
A combustor for heating the reformer;
A method of operating a fuel cell system comprising a fuel cell that generates electricity using the hydrogen-containing gas discharged from the CO reducer,
At the time of start-up, the reformer is heated by the combustion operation of the combustor, the raw material gas is supplied to the reformer through the first path, and at least a part of the gas discharged from the CO reducer is supplied. An operation method of a fuel cell system, wherein a circulation operation for returning to the first path through the second path is executed.

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