JP5283330B2 - Operation method of hydrogen generator and hydrogen generator - Google Patents

Description

  The present invention relates to an operation of a hydrogen generator for producing hydrogen to be used in a hydrogen-using device such as a fuel cell using water and a hydrocarbon-based material such as natural gas, liquefied petroleum gas, gasoline, naphtha, kerosene, and methanol. The present invention relates to a method and a hydrogen generator.

  Hydrogen is attracting attention as one of the promising energy sources to replace fossil fuels, but social infrastructure such as hydrogen pipelines is required for its effective use. One method is to use natural gas, other fossil fuels, alcohol, and other infrastructure that has already been built, such as transportation and transportation, and reform these fuels where hydrogen is needed to generate hydrogen. Is being considered. For example, natural gas (city gas) reforming technology for fuel cells as small-scale on-site power generation devices, methanol reforming technology for fuel cells for automobile power sources, etc. have been proposed in various forms. ing. Catalytic reactions at high temperatures are used to reform these raw materials to generate hydrogen, and typical methods include a partial oxidation method, a steam reforming method, and a method called autothermal method using both in combination. .

However, since the reforming reaction proceeds at a high temperature, carbon monoxide (CO) and carbon dioxide (CO ₂ ) are generated as a double product from the reaction equilibrium together with hydrogen as a product. When using the produced hydrogen in fuel cells, especially in polymer fuel cells, CO, which is a by-product, poisons the electrodes of the fuel cell and significantly degrades its performance, so the CO concentration is kept as low as possible. It is necessary to keep it. Therefore, it is common to employ a method of adding a shift reaction section and a CO removal section downstream of the reforming reaction section to reduce the CO concentration to several tens of ppm. At this time, the reforming reaction section employs a ruthenium or nickel-based reforming catalyst, and in most cases, the shift reaction section employs a copper-based metal catalyst because of its excellent reaction activity, and the CO removal section. A precious metal catalyst is used for the. In this series of reaction systems, about 10% concentration of CO produced in the reforming reaction section is reduced to 1% or less in the shift reaction section, and further reduced to several tens of ppm in the CO removal section. (Refer to Patent Document 1 etc.).

  As described above, a hydrogen generator for supplying hydrogen to a fuel cell, particularly a polymer fuel cell, generally passes through a reforming reaction, a shift reaction, and a CO removal reaction. As a catalyst, a base metal such as nickel or a noble metal such as ruthenium is used for the reforming reaction, a copper base metal is used for the metamorphic reaction, and a noble metal such as platinum or ruthenium is used for the CO removal part. It was. At this time, the base metals in the above catalyst are those that are highly active as a catalyst in the reduced (metal) state. However, when oxidized, the activity is lost, and once oxidized, the reduction operation is performed next. It was difficult to recover the original activity even if added. Of course, it was difficult to maintain the activity in the repeated process of repeated oxidation / reduction.

  In particular, the copper-based catalyst used in the shift reaction section is easily oxidized by air or water vapor as compared with the metal catalyst used in the reforming reaction section or the CO removal section, and water is condensed on the catalyst. There is a problem that it is easily destroyed physically by repeated evaporation.

Therefore, it is necessary to keep the reaction system always in a reduced state during operation, and at the same time, the catalyst is filled with an inert gas such as nitrogen or is circulated when the operation is stopped, during heat-up, or during cool-down. There is a problem that it is necessary to prevent the oxidation of the. This operation can be solved by preparing a nitrogen cylinder or the like beside the hydrogen generator in a situation that can be managed by a specialized driver, but for example, when applied to household equipment or automobiles, etc. However, it is difficult to arrange a high-pressure cylinder such as nitrogen, which has been a major problem when applied to small-scale distributed devices such as household appliances and automobiles in the future. In particular, when the operation state is shifted to the operation stop state, the internal gas contracts, and if the separation from the atmosphere is insufficient, the air is mixed in and the catalyst is oxidized to reduce its activity. There is a problem that a structure similar to a pressure vessel that overcomes the pressure difference is required in order to sufficiently isolate and prevent air contamination.
JP 2002-293506 A

  The present invention has been made in view of the above points, and without using an inert gas such as nitrogen gas as a purge gas when the hydrogen generator is started up, the catalyst in the reforming reaction section or the shift reaction section is used. An object of the present invention is to provide a method of operating a hydrogen generator and a hydrogen generator that can maintain activity and are excellent in operability and convenience.

  A method for operating a hydrogen generator according to the present invention includes a reforming reaction section 1 that includes a reforming catalyst containing at least Ni or Ru, and generates a reformed gas containing hydrogen from a raw fuel gas and steam by a steam reforming reaction. And a shift reaction section 2 for reducing CO gas contained in the reformed gas by an aqueous shift reaction, and heating sections 4 and 10 for heating the reform reaction section 1 and the shift reaction section 2. An operation method of the apparatus, wherein the reforming reaction section 1 and the shift reaction section 2 are heated up to predetermined reaction temperatures T4 and T5 from the state where the operation of the hydrogen generator is stopped, respectively, A normal operation process in which a mixed gas containing raw fuel gas and water vapor is supplied to the reforming reaction section 1 with the quality reaction section 1 and the shift reaction section 2 maintained at the reaction temperatures T4 and T5, respectively. During the startup process In the state where the temperature of the shift reaction unit 2 is equal to or lower than the first dew point T1, which is the dew point in the shift reaction unit 2 when the mixed gas containing raw fuel gas and water vapor is circulated through the shift reaction unit 2. While maintaining the temperature of the reforming reaction section 1 below the carbon deposition temperature T3, which is the temperature at which carbon deposition on the surface of the reforming catalyst starts when the raw fuel is passed through the reforming reaction section 1. After the raw fuel gas is supplied to the reforming reaction section 1 without supplying water vapor, and the temperature of the reforming reaction section 1 becomes equal to or higher than the carbon deposition temperature T3, the temperatures of the reforming reaction section 1 and the shift reaction section 2 While the temperature of each is raised to a predetermined reaction temperature T4, T5, a mixed gas of raw fuel gas and water vapor is supplied to the reforming reaction section 1.

Thus, in the start-up process, until the temperature of the shift reaction unit 2 reaches the first dew point T1, steam is not supplied to the reforming reaction unit 1, but only raw fuel is supplied as a purge gas. When the temperature does not reach the first dew point T1, water vapor does not flow through the shift reaction section 2 and only the raw fuel flows, and water droplets do not adhere to the surface of the shift catalyst in the shift reaction section 2. . Further, while the raw fuel is supplied to the reforming reaction unit 1 without supplying water vapor, the temperature of the reforming reaction unit 1 is lower than the carbon deposition temperature T3. No carbon deposition on the surface of the reforming catalyst due to decomposition of. Further, when the temperature of the reforming reaction unit 1 becomes equal to or higher than the carbon deposition temperature T3, the steam reforming reaction proceeds even if a mixed gas of raw fuel and steam is supplied to the reforming reaction unit 1. Thus, no carbon deposition occurs on the surface of the reforming catalyst, and a reformed gas containing hydrogen can be generated by this steam reforming reaction.
In addition, it is preferable to design the hydrogen generator so that the first dew point is in the range of 62 to 93 ° C.

  In the start-up process, the temperature of the reforming reaction section 1 is a mixed gas containing raw fuel gas and water vapor in the reforming reaction section 1 before the temperature of the shift reaction section 2 reaches the first dew point T1. When the temperature reaches the second dew point T2, which is the dew point in the reforming reaction unit 1 when the gas is circulated, after the temperature of the shift reaction unit 2 exceeds the first dew point T1, the temperature of the reforming reaction unit 1 is carbon deposited. In a state below the temperature T3, it is preferable to supply at least one of raw fuel and water vapor to the reforming reaction section 1. In this case, if either one of the temperature of the shift reaction unit 2 is equal to or lower than the first dew point T1 and the temperature of the reforming reaction unit 1 is equal to or lower than the second dew point T2, the reforming is performed. The raw fuel is supplied without supplying steam to the reaction unit 1, and when the temperature of the reforming reaction unit 1 does not reach the second dew point T <b> 2, steam flows through the reforming reaction unit 1. In other words, only the raw fuel flows and water drops do not adhere to the surface of the reforming catalyst. Further, after the temperature of the shift reaction section 2 exceeds the first dew point T1, when the temperature of the reforming reaction section 1 is lower than the carbon deposition temperature T3, either the raw fuel alone, the steam alone, or the mixed gas of both is modified. Even if it is supplied to the quality reaction unit 1, water droplets do not adhere to the surfaces of the reforming catalyst and shift catalyst, and carbon does not deposit on the surface of the reforming catalyst.

  At this time, when the temperature of the reforming reaction unit 2 reaches a predetermined temperature lower than the carbon deposition temperature T3 before the temperature of the shift reaction unit 2 reaches the first dew point T1, the temperature of the shift reaction unit 2 is It is preferable to operate the heating unit 4 intermittently until the first dew point T1 is reached to maintain the temperature of the reforming reaction unit 1 at a temperature lower than the carbon deposition temperature T3. In this way, by suppressing the temperature rise of the reforming reaction unit 1 before the temperature of the shift reaction unit 2 reaches the first dew point T1, reforming is performed before the temperature of the shift reaction unit 2 reaches the first dew point T1. In the state where the raw fuel is supplied to the reaction unit 1 without supplying water vapor, the temperature of the reforming reaction unit 1 is prevented from reaching the carbon deposition temperature T3, and carbon is deposited on the surface of the reforming catalyst at this time. Can be reliably prevented.

  Further, in the start-up process, after the temperature of the shift reaction section 2 reaches the first dew point T1, the temperature of the reforming reaction section 1 includes raw fuel gas and water vapor in the reforming reaction section 1. When reaching the second dew point T2, which is the dew point in the reforming reaction unit 1 when the mixed gas is circulated, the temperature of the reforming reaction unit 1 is increased after the temperature of the shift reaction unit 2 exceeds the first dew point T1. In the state where the dew point is less than or equal to the second dew point T2, the raw fuel gas is supplied without supplying steam to the reforming reaction unit 1, and after the temperature of the reforming reaction unit 1 exceeds the second dew point T2, reforming is performed. In a state where the temperature of the reaction unit 1 is lower than the carbon deposition temperature T3, it is preferable to supply at least one of raw fuel and steam to the reforming reaction unit 1. In this case as well, if either one of the temperature of the shift reaction section 2 is equal to or lower than the first dew point T1 and the temperature of the reforming reaction section 1 is equal to or lower than the second dew point T2, the reform is performed. The raw fuel is supplied without supplying water vapor to the quality reaction unit 1, and in a state where the temperature of the reforming reaction unit 1 has not reached the second dew point T <b> 2, steam flows through the reforming reaction unit 1. In this case, only the raw fuel is circulated, and no water droplets adhere to the surface of the reforming catalyst. In addition, after the temperature of the reforming reaction section 1 exceeds the second dew point T2, when the temperature of the reforming reaction section 1 is lower than the carbon deposition temperature T3, only the raw fuel, only the steam, or the mixed gas of both are used. Even if it is supplied to the reforming reaction section 1, water droplets do not adhere to the surfaces of the reforming catalyst and shift catalyst, and carbon does not deposit on the surface of the reforming catalyst.

  In such an operation method of the hydrogen generator, it is preferable that the shift reaction unit 2 includes a shift catalyst containing at least copper. In this case, it is cheaper than other catalysts and the effect of the present invention is more remarkable.

  Moreover, it is preferable to design the hydrogen generator so that the second dew point is in the range of 90 to 100 ° C. In this case, it is easy to prevent water from condensing in the reforming reaction unit 1, and the temperature raising rate can be shortened, so that the startup energy can be suppressed.

  Moreover, it is preferable that the said carbon deposition temperature is 200-300 degreeC. In this case, deterioration of the reforming catalyst is suppressed, and a hydrogen generator having excellent durability is obtained.

  The hydrogen generator according to the present invention includes a reforming catalyst including a reforming catalyst containing at least Ni or Ru, and generates a reformed gas containing hydrogen from a raw fuel gas and steam by a steam reforming reaction, An operation of a hydrogen generator, comprising a shift reaction section 2 for reducing CO gas contained in the reformed gas by an aqueous shift reaction, and heating sections 4 and 10 for heating the reform reaction section 1 and the shift reaction section. After the start-up process of raising the reforming reaction part 1 and the shift reaction part 2 to the predetermined reaction temperatures T4 and T5 from the state where the reaction is stopped, the reforming reaction part 1 and the shift reaction part 2 are respectively A hydrogen generator for producing hydrogen by a normal operation process in which a mixed gas containing raw fuel gas and water vapor is supplied to the reforming reaction section 1 while maintaining the reaction temperatures T4 and T5. Before When the raw fuel is supplied to the reforming reaction section 1 without supplying water vapor, the temperature of the reforming reaction section 1 is the temperature at which carbon deposition starts on the surface of the reforming catalyst. Before the temperature is raised to T3, the temperature of the shift reaction unit 2 is raised to a temperature equal to or higher than the first dew point T1, which is the dew point in the shift reaction unit 2 when the mixed gas is supplied to the shift reaction unit 2. And a control means for controlling the heating of the reforming reaction section 1 and the shift reaction section 2 by the heating sections 4 and 10.

  By operating such a hydrogen generator, in the start-up process, steam is not supplied to the reforming reaction section 1 until the temperature of the shift reaction section 2 reaches the first dew point T1, and only raw fuel is supplied as a purge gas. By doing so, in the state where the temperature of the shift reaction section 2 has not reached the first dew point T1, steam does not flow through the shift reaction section 2, but only the raw fuel flows, so that the shift of the shift reaction section 2 is shifted. Water drops do not adhere to the surface of the catalyst. While the raw fuel is supplied to the reforming reaction section 1 without supplying water vapor, the temperature of the reforming reaction section 1 is maintained below the carbon deposition temperature T3 by the control means. Then, carbon deposition on the surface of the reforming catalyst due to decomposition of the raw fuel does not occur. Further, when the temperature of the reforming reaction unit 1 becomes equal to or higher than the carbon deposition temperature T3, the steam reforming reaction proceeds even if a mixed gas of raw fuel and steam is supplied to the reforming reaction unit 1. Thus, no carbon deposition occurs on the surface of the reforming catalyst, and a reformed gas containing hydrogen can be generated by this steam reforming reaction.

  The steam generator preferably includes a temperature detection means for detecting the temperatures of the reforming reaction unit 1 and the shift reaction unit 2. In this case, the heating control of the reforming reaction unit 1 and the shift reaction unit 2 can be performed based on the detection result of the temperature detection means.

  According to the present invention, without using an inert gas such as nitrogen gas as a purge gas when the hydrogen generator is started, the raw fuel is converted to the reforming reaction portion temperature when the temperature of the shift reaction portion is below the first dew point. However, at a temperature higher than the carbon deposition temperature, a mixed gas of raw fuel and water vapor can be used as a purge gas, and a purge in the startup process can be performed without providing a separate inert gas supply means. Adhesion of water droplets on the surface of the shift catalyst and precipitation of carbon on the surface of the reforming catalyst can be prevented, and a decrease in catalyst activity can be prevented.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 conceptually shows an example of the configuration of the hydrogen generator.

  The reforming reaction section 1 is filled with a reforming catalyst containing at least one of nickel (Ni) or ruthenium (Ru), and a mixed gas of raw fuel and steam is generated during normal operation of the hydrogen generator. A reformed gas containing hydrogen is generated by an aqueous reforming reaction. This reaction is an endothermic reaction. When a hydrocarbon-based raw fuel is used, the reaction temperature T5 is usually preferably set in the range of 600 to 800 ° C. The reforming reaction unit 1 is provided with a temperature detector 8 such as a thermocouple or a high temperature type thermistor for measuring the temperature of the gas inside the reforming reaction unit 1.

The shift reaction section 2 is filled with a copper-based shift catalyst, and the reformed gas generated in the reforming reaction section 1 is supplied during normal operation of the hydrogen generator, and the reformed gas is generated by an aqueous shift reaction. Most of the CO inside is converted to CO ₂ to reduce the CO concentration in the reformed gas. This reaction is an exothermic reaction, and the reaction temperature T4 is usually preferably set in the range of 200 to 300 ° C. The shift reaction unit 2 is provided with a temperature detector 9 such as a thermocouple for measuring the temperature of the gas inside the shift reaction unit 2.

In the illustrated example, a CO removing unit 3 is also provided. The CO removal unit 3 is filled with a CO oxidation catalyst such as platinum or ruthenium. During the normal operation of the hydrogen generator, the reformed gas is supplied from the shift reaction unit 2, and the CO still remaining in the reformed gas is converted into CO. It is oxidized to CO ₂ by a selective oxidation reaction, and the CO concentration in the reformed gas is further reduced. This reaction is an exothermic reaction, and the reaction temperature is usually preferably set in the range of 120 to 180 ° C.

  A water supply unit 5 and a raw fuel supply unit 6 are connected to the reforming reaction unit 1. The water supply unit 5 supplies water to the reforming reaction unit 1 through a water supply path 11 connecting the two, and water is supplied to the reforming reaction unit 1 heated at this time. The steam is supplied to the reforming reaction unit 1. The raw fuel supply unit 6 includes a cylinder filled with the raw fuel, and the raw fuel supply unit 6 supplies the raw fuel to the reforming reaction unit 1 via a raw fuel supply path 12 connecting the two. Supply. The raw fuel can be a hydrocarbon-based gas or liquid fuel such as butane gas, or an alcohol-based fuel, such as natural gas, liquefied petroleum gas, gasoline, naphtha, kerosene, methanol, etc. Can be used. By supplying the raw fuel from the raw fuel supply unit 6 to the heated reforming reaction unit 1, gaseous raw fuel is supplied to the reforming reaction unit 1.

  In the illustrated example, a merged supply path 13 where the water supply path 11 and the raw fuel supply path 12 merge is connected to the reforming reaction unit 1, and water and raw fuel are mixed in the merged supply path 13. Is supplied to the reforming reaction section 1, whereby a gas mixture of water vapor and raw fuel is supplied to the reforming reaction section 1. However, the water supply path 11 and the raw fuel supply path 12 are separately connected to the reforming reaction unit 1 so that the steam and the raw fuel are mixed in the reforming reaction unit 1, thereby reforming. A mixed gas of water vapor and raw fuel may be supplied to the reaction unit 1.

  The heating unit 4 heats the reforming reaction unit 1 and the shift reaction unit 2 and can be configured by a burner, a catalytic combustion apparatus, or the like. The heating unit 4 is supplied with combustion fuel and combustion air, and generates a heating gas by a combustion reaction between the combustion fuel and the combustion air. Then, heat energy is supplied to the reforming reaction section 1 and the shift reaction section 2 using the heated gas as a medium, and these are heated.

  A combustion air supply unit 7 constituted by an air pump or the like is connected to the heating unit 4 via a combustion air supply channel 14, and a raw fuel supply unit 6 is connected via a combustion fuel supply channel 15. Has been. At this time, in the example shown in the drawing, the combustion merging supply path 16 where the combustion air supply path 14 and the combustion fuel supply path 15 merge is connected to the heating unit 4. Thereby, the combustion air is supplied from the combustion air supply unit 7 to the heating unit 4 and the raw fuel is supplied from the raw fuel supply unit 6 as the combustion fuel.

  The water supply passage 11, the raw fuel supply passage 12, the combustion air supply passage 14 and the combustion fuel supply passage 15 are provided with regulating valves 17, 18, 19 and 20, respectively.

  In the example shown in the figure, the transformation reaction unit 2 is provided with a heating unit 10 separate from the heating unit 4. The heating unit 10 can be constituted by a heater, a catalytic combustion device, or the like. The heating unit 10 can heat the shift reaction unit 2 together with the heating unit 4.

  Further, the hydrogen generator is provided with a control unit 21 as control means for controlling the operation of the hydrogen generator. The control unit 21 controls the supply amount of raw fuel and steam to the reforming reaction unit 1 based on the temperature information of the reforming reaction unit 1 and the shift reaction unit 2 measured by the detectors 8 and 9, Temperature control of the quality reaction part 1 and the transformation reaction part 2 is performed. At this time, the control unit 21 outputs a control signal to the regulating valve 17 and the regulating valve 18 to perform opening / closing control and opening degree control, thereby controlling the supply amount of raw fuel and steam to the reforming reaction unit 1. Further, the control signal is output to the regulating valve 19 and the regulating valve 20 to control the opening and closing thereof, and the opening degree is controlled, and the control signal is output to the heating units 4 and 10 to output the reforming reaction unit 1 and the shift reaction unit 2. The temperature control of the reforming reaction unit 1 and the shift reaction unit 2 can be performed by controlling the supply of heat energy to the gas. Such a control unit 21 receives, for example, temperature detection information of the reforming reaction unit 1 and the shift reaction unit 2 output from the temperature detectors 8 and 9 and converts this information into information that can be read by the arithmetic processing unit. An input device to be converted, an arithmetic processing device that performs arithmetic processing based on information transmitted from the input device, and generates operation control signals for the regulating valves 17, 18, 19, and 20 and the heating units 4 and 10 are operated. A storage device storing programs to be executed and reference information, and an output device for outputting operation control signals generated by the arithmetic processing device to the adjusting valves 17, 18, 19, 20 and the heating units 4, 10. .

  In generating hydrogen in the above hydrogen generator, the first dew point T1, the second dew point T2, the carbon deposition temperature T3, the reaction temperature T4 in the shift reaction unit 2, and the reaction temperature T5 in the reforming reaction unit 1, The information is stored in the control unit 21 as reference information.

  The first dew point T1 is the dew point (the surface of the shift catalyst) in the shift reaction section 2 in a state where a mixed gas containing raw fuel gas and water vapor at the same predetermined ratio as in normal operation is circulated through the shift reaction section 2. Temperature at which water droplets begin to adhere to the surface). This first dew point T1 is a value depending on the ratio of water vapor and raw fuel in the mixed gas during normal operation, the amount of gas flow in the shift reaction section 2, and the internal structure of the shift reaction section 2, and hydrogen generation Prior to the operation of the apparatus, it can be derived by actual measurement.

  It is preferable to design the hydrogen generator so that the first dew point T1 is in a range of 62 to 93 ° C, and is set to 90 ° C, for example. The value of the first dew point T1 can be set by adjusting, for example, the reaction temperature, the supply amount ratio between the raw fuel and water vapor, the supply pressure, and the like.

  The second dew point T2 is a dew point (reformation in the reforming reaction unit 1 in a state in which a mixed gas containing raw fuel gas and water vapor in the same predetermined ratio as in normal operation is circulated through the reforming reaction unit 1. Temperature at which water droplets start to adhere to the surface of the catalyst). This second dew point T2 is a value that depends on the ratio of water vapor and raw fuel in the mixed gas during normal operation, the amount of gas flow in the reforming reaction section 1, and the internal structure of the reforming reaction section 1. It can be derived by actual measurement prior to the operation of the hydrogen generator.

  It is preferable to design the hydrogen generator so that the second dew point T2 is in the range of 90 to 100 ° C, and is set to 100 ° C, for example. The value of the second dew point T2 can be set, for example, by adjusting the supply amount ratio between the raw fuel and the water vapor.

  The carbon deposition temperature T3 is such that the raw fuel is decomposed in the reforming reaction unit 1 in a state in which the raw fuel is supplied without supplying steam to the reforming reaction unit 1, and carbon deposition occurs on the surface of the reforming catalyst. It is the starting temperature. This carbon deposition temperature T3 depends on the ratio of water vapor and raw fuel in the mixed gas during normal operation, the gas flow rate in the reforming reaction section 1, the internal structure of the reforming reaction section 1, and the type of reforming catalyst. And can be derived by actual measurement prior to the operation of the hydrogen generator. This value is generally set in the range of 200 to 300 ° C.

  This carbon deposition temperature T3 varies mainly depending on the type of raw fuel and the type of reforming catalyst. For example, when 13A city gas is used as the raw fuel, Ni containing is used as the reforming catalyst. Can be set to 300 ° C. and 500 ° C. when a material containing Ru is used.

  The reaction temperature T4 in the shift reaction section 2 is the temperature of the shift reaction section 2 during normal operation, and is usually set in the range of 200 to 300 ° C. as described above.

  The reaction temperature T5 in the reforming reaction unit 1 is the temperature of the reforming reaction unit 1 during normal operation, and is usually set in the range of 600 to 800 ° C. as described above.

  In the start-up process in which the temperature of the reforming reaction section 1 and the shift reaction section 2 is increased to the predetermined reaction temperatures T4 and T5 by starting the hydrogen generator from a stopped state, the temperature of the shift reaction section 2 is increased in the present invention. In a state where the temperature is equal to or lower than the first dew point T1, the reforming reaction unit 1 is maintained at a temperature lower than the carbon deposition temperature T3, and the raw fuel gas is supplied to the reforming reaction unit 1 without supplying water vapor. After the temperature of 1 becomes equal to or higher than the carbon deposition temperature T3, a mixed gas of raw fuel gas and water vapor is supplied to the reforming reaction section 1.

  In this startup process, after the operation of the hydrogen generator is started, the control unit 21 first closes the adjustment valve 17 so that water is not supplied from the water supply unit 5 to the reforming reaction unit 1, and the adjustment valve 18 is opened to a predetermined degree. The raw fuel is supplied at a predetermined flow rate from the raw fuel supply unit 6 to the reforming reaction unit 1, and the regulating valve 19 and the regulating valve 20 are opened at a predetermined degree of opening to feed the raw fuel from the raw fuel supply unit 6. Control that supplies air from the air supply unit 7 to the heating unit 4 at a predetermined flow rate and operates the heating units 4 and 10 to supply heat energy to the reforming reaction unit 1 and the shift reaction unit 2 to heat them. I do.

  After the temperature increase of the reforming reaction unit 1 and the shift reaction unit 2 is started in this way, the operation of the hydrogen generator is performed according to the manner in which the temperature of the reforming reaction unit 1 and the shift reaction unit 2 is increased. Branch to the street operation sequence.

  In the first operation sequence shown in the graph of FIG. 2, after the heating of the reforming reaction unit 1 and the shift reaction unit 2 by the heating units 4 and 10 is started, the temperature of the shift reaction unit 2 reaches the first dew point T1. This is a case where the temperature of the reforming reaction section 1 reaches the second dew point T2 before reaching. In this case, the control unit 21 performs the following operation so that the raw fuel is not supplied to the reforming reaction unit 1 until the temperature of the shift reaction unit 2 reaches the first dew point T1 (region A in the drawing). After the gas is supplied and the temperature of the shift reaction section 2 exceeds the first dew point T1, the reforming reaction section 1 is in the reforming reaction section 1 when the temperature of the reforming reaction section 1 is lower than the carbon deposition temperature T3 (region B in the figure). At least one of raw fuel and water vapor is supplied.

  First, the control unit 21 sets the temperature of the reforming reaction unit 1 detected by the temperature detector 8 in the state where the temperature of the shift reaction unit 2 detected by the temperature detector 9 is lower than the first dew point T1. When recognizing that the dew point T2 has been reached, the operations of the regulating valves 17, 18, 19, 20 and the heating units 4, 10 are maintained as they are.

  Thereafter, when the control unit 21 recognizes that the temperature of the shift reaction unit 2 detected by the temperature detector 9 has exceeded the first dew point T1, the control unit 21 opens the regulating valve 18 to a predetermined opening degree. Control to open with. At the same time, the control unit 21 may perform control to close the adjustment valve 17. Alternatively, each regulating valve 17 may be opened at a predetermined opening and the regulating valve 18 may be kept closed. Thereby, one of raw fuel and steam is supplied to the reforming reaction section 1 or a mixed gas of raw fuel and steam is supplied.

  Next, when the control unit 2 detects that the temperature of the reforming reaction unit 1 detected by the temperature detector 8 has reached the carbon deposition temperature T3, the control unit 21 opens the adjustment valve 17 at a predetermined opening. At the same time, the control valve 17 and the control valve 18 are controlled so as to open the control valve 18 at a predetermined opening, and a mixed gas of raw fuel and water vapor is supplied to the reforming reaction section 1 (region C in the drawing). At the same time, the control unit 21 increases or decreases the thermal energy transmitted from the heating unit 4 to the reforming reaction unit 1 or the shift reaction unit 2 by changing the opening degree of the regulating valves 19 and 20, or from the heating unit 10. When control is performed to increase or decrease the thermal energy transmitted to the shift reaction section 2, the time required for startup is shortened by increasing the rate of temperature increase of the reforming reaction section 1 and shift reaction section 2, It is possible to adjust the temperature rising rates of the reforming reaction unit 1 and the shift reaction unit 2 so that the shift reaction unit 2 reaches the reaction temperature T4 and the reforming reaction unit 1 reaches the reaction temperature T5 at the same time.

  When the shift reaction unit 2 reaches the reaction temperature T4 and the reforming reaction unit 1 reaches the reaction temperature T5, the start-up process ends and the process shifts to a normal operation process.

  In the normal operation process, when the control unit 21 recognizes that the temperature detected by the temperature detector 9 is equal to or higher than the reaction temperature T4, the control unit 21 stops the supply of heat energy to the shift reaction unit 2 by the heating units 4 and 10. When it is recognized that the detected temperature is lower than the reaction temperature T4, the heating units 4 and 10 are intermittently operated so as to supply heat energy from the heating units 4 and 10 to the transformation reaction unit 2 The temperature of the shift reaction part 2 is maintained at the reaction temperature T4. Further, when the control unit 21 recognizes that the temperature detected by the temperature detector 8 is equal to or higher than the reaction temperature T5, the control unit 21 stops the supply of thermal energy to the reforming reaction unit 1 by the heating unit 4, and this detected temperature is the reaction temperature. When it is recognized that the temperature is lower than T5, the heating unit 4 is intermittently operated so as to supply heat energy from the heating unit 4 to the reforming reaction unit 1. The temperature is maintained at reaction temperature T5.

  In this way, during the transition from the startup process to the normal operation process and during this normal operation process, the control unit 21 does not significantly change the operation of the adjustment valve 17 and the adjustment valve 18, and the adjustment valve 17 has a predetermined value. While being opened at the opening, the adjustment valve 18 is maintained at a predetermined opening so that a mixed gas of raw fuel and steam is supplied to the reforming reaction section 1.

  When the hydrogen generator is operated as described above, in the start-up process, the heating units 4 and 10 are operated to start the temperature raising of the reforming reaction unit 1 and the shift reaction unit 2, and then the reforming reaction unit 1 Until the temperature of the shift reaction section 2 reaches the first dew point T1 in the state where the temperature is lower than the carbon deposition temperature T3 (region A in the figure), steam is not supplied to the reforming reaction section 1 and only the raw fuel is supplied. Supplied as purge gas. For this reason, in a state where the temperature of the shift reaction section 2 has not reached the first dew point T1, water vapor does not flow through the shift reaction section 2, but only raw fuel flows, and the shift catalyst of the shift reaction section 2 Water drops will not adhere to the surface. Further, in a state where the temperature of the reforming reaction unit 1 does not reach the second dew point T2, water vapor does not flow through the reforming reaction unit 1, but only raw fuel flows, and water droplets are also formed on the surface of the reforming catalyst. Will not adhere. Further, while the raw fuel is supplied to the reforming reaction unit 1 without supplying water vapor, the temperature of the reforming reaction unit 1 is lower than the carbon deposition temperature T3. No carbon deposition on the surface of the reforming catalyst due to decomposition of.

  In addition, after the temperature of the shift reaction section 2 exceeds the first dew point T1 and before the carbon deposition temperature T3 is reached (region B in the figure), the reforming reaction section 1 has either raw fuel or steam. One or a mixed gas of raw fuel and water vapor is supplied as a purge gas. At this time, only the water vapor, only the raw fuel, or a mixed gas with water vapor flows through the reforming reaction unit 1 and the shift reaction unit 2. Since the dew point T2 or higher and the shift reaction section 2 is higher than the first dew point T1, water droplets do not adhere to the reforming catalyst and the shift catalyst, and no carbon is deposited on the surface of the reforming catalyst.

  In addition, after the temperature of the reforming reaction unit 1 reaches the carbon deposition temperature T3 (region C in the figure), the reforming reaction unit 1 is supplied with a mixed gas of raw fuel and steam. Since the steam reforming reaction proceeds in the reaction section 1, no carbon deposition occurs on the surface of the reforming catalyst, and the reformed gas containing hydrogen produced by the steam reforming reaction is derived from the hydrogen generator. Thus, it can be used for a fuel cell or the like.

In addition, after the reforming reaction unit 1 reaches the predetermined reaction temperature T5 and the shift reaction unit 2 reaches the predetermined reaction temperature T4 and shifts to the normal operation process (region D in the figure), the reforming reaction unit 1 A gas mixture of raw fuel and water vapor is supplied to the reforming reaction section 1 in a state where the reaction temperature T5 is maintained and the shift reaction section 2 is maintained at the reaction temperature T4. At this time, first, the steam reforming reaction proceeds in the reforming reaction section 1, and a reformed gas containing hydrogen is generated. This reformed gas is sent to the shift reaction section 2, where most of the CO in the reformed gas is converted to CO ₂ by the aqueous shift reaction in the shift reaction section 2, and the CO concentration in the reformed gas is reduced. This reformed gas is further sent to the CO removing unit 3 where the CO still remaining in the reformed gas is oxidized to CO ₂ by the CO selective oxidation reaction, and the CO concentration in the reformed gas is further reduced. Is done.

  This reformed gas is led out from the hydrogen generator and can be used as fuel for fuel cells.

  In the first operation sequence, as described above, the temperature of the reforming reaction unit 1 is maintained below the carbon deposition temperature T3 until the temperature of the shift reaction unit 2 reaches the first dew point T1. For this reason, when the temperature increase rate of the reforming reaction unit 1 after the start of operation of the hydrogen generator is high, the temperature of the reforming reaction unit 1 is set to carbon until the temperature of the shift reaction unit 2 reaches the second dew point. It is necessary to perform an operation for maintaining the temperature below the deposition temperature T3. For this reason, in the start-up process, when the temperature of the reforming reaction unit 1 reaches a predetermined temperature lower than the carbon deposition temperature T3 before the temperature of the shift reaction unit 2 reaches the first dew point T1, the temperature of the shift reaction unit 2 is The heating unit 4 is intermittently operated until the first dew point T1 is reached, and the temperature of the reforming reaction unit 1 is maintained at the predetermined temperature, thereby maintaining the temperature of the reforming reaction unit 1 below the carbon deposition temperature T3. It is preferable. The predetermined temperature can be set to an appropriate temperature slightly lower than the carbon deposition temperature T3. However, in the process in which the temperature of the reforming reaction section 1 is maintained at the predetermined temperature, the temperature does not reach the carbon deposition temperature T3 due to overshoot. Therefore, for example, the predetermined temperature is set to a temperature lower by 30 to 100 ° C. than the carbon deposition temperature T3.

  The second operation sequence shown in the graph of FIG. 3 is obtained by adding an operation for maintaining the temperature of the reforming reaction unit 1 below the carbon deposition temperature T3 in the first operation sequence.

  At this time, first, when the control unit 21 recognizes that the temperature of the reforming reaction unit 1 detected by the temperature detector 8 has reached the second dew point T2, the shift reaction unit detected by the temperature detector 9 is used. If the temperature is less than the first dew point T1, the operations of the regulating valves 17, 18, 19, 20 and the heating units 4, 10 are maintained as they are.

  Thereafter, before the temperature of the shift reaction unit 2 detected by the temperature detector 9 reaches the first dew point T1, the control unit determines that the temperature of the reforming reaction unit 1 has reached a predetermined temperature lower than the carbon deposition temperature T3. When the controller 21 recognizes, the controller 21 stops the supply of heat energy to the reforming reaction unit 1 by the heating unit 4 when it recognizes that the temperature detected by the temperature detector 8 is equal to or higher than the predetermined temperature. When it is recognized that the detected temperature is lower than the predetermined temperature, the heating unit 4 is controlled to operate intermittently so as to supply thermal energy from the heating unit 4 to the reforming reaction unit 1, and the shift reaction unit 2 The temperature is maintained at the predetermined temperature.

  Next, when the control unit 21 recognizes that the temperature of the shift reaction unit 2 detected by the temperature detector 9 has reached the first dew point T1, the heating unit 4 supplies thermal energy to the reforming reaction unit 1. The operation of the heating unit 4 is controlled so as to supply continuously, and the reforming reaction unit 1 is heated. At the same time, the control unit 21 performs control to open the adjustment valve 17 at a predetermined opening and to open the adjustment valve 18 at a predetermined opening. Further, at this time, as shown in the figure, the thermal energy transmitted from the heating units 4 and 10 to the shift reaction unit 2 is increased, and the temperature increase rate of the shift reaction unit 2 is increased to shorten the time required for startup. At the same time, the temperature raising rates of the reforming reaction unit 1 and the shift reaction unit 2 may be adjusted so that the shift reaction unit 2 reaches the reaction temperature T4 and the reforming reaction unit 1 reaches the reaction temperature T5 at the same time.

  Subsequent operations are the same as those in the first operation sequence.

  When the hydrogen generator is operated as described above, even when the temperature increase rate of the reforming reaction section 1 after the start of the operation of the hydrogen generation apparatus is high, the temperature of the shift reaction section 2 is below the first dew point T1. In some cases, the temperature of the reforming reaction unit 1 is maintained at a temperature lower than the carbon deposition temperature T3, and even if the raw fuel is supplied to the reforming reaction unit 1 without supplying water vapor in this state, the reforming reaction is performed. No carbon is deposited on the surface of the reforming catalyst of part 1.

  In the third operation sequence shown in the graph of FIG. 4, after the heating temperature of the reforming reaction unit 1 and the shift reaction unit 2 by the heating units 4 and 10 is started, the reforming reaction unit 1 reaches the second dew point T2. In this case, the shift reaction unit 2 reaches the first dew point T1 before reaching the first dew point T1, and then the reforming reaction unit 1 reaches the second dew point T2. In this case, the control unit 21 performs the following operation to supply the raw fuel gas without supplying steam to the reforming reaction unit 1 until the temperature of the shift reaction unit 2 reaches the first dew point, thereby performing the shift reaction. After the temperature of the part 2 exceeds the first dew point T1, when the temperature of the reforming reaction part 1 is equal to or lower than the second dew point T2, the raw fuel gas is continuously supplied without supplying steam to the reforming reaction part 1. After the temperature of the reforming reaction unit 1 exceeds the second dew point T2, when the temperature of the reforming reaction unit 1 is lower than the carbon deposition temperature T3, at least one of raw fuel and water vapor is supplied to the reforming reaction unit. To supply.

  First, the control unit 21 sets the temperature of the reforming reaction unit 2 detected by the temperature detector 9 in the state where the temperature of the reforming reaction unit 1 detected by the temperature detector 7 is lower than the second dew point T2. When recognizing that the dew point T1 has been reached, the operation of the regulating valves 17, 18, 19, 20 and the heating units 4, 10 is maintained as they are.

  Thereafter, when the control unit 21 recognizes that the temperature of the reforming reaction unit 1 detected by the temperature detector 7 has reached the second dew point T2, the control unit 21 controls the opening of the regulating valve 18 at a predetermined opening degree. I do. At the same time, the control unit 21 may output a control signal to the regulating valve 17 to close the regulating valve 17. Alternatively, each regulating valve 17 may be opened at a predetermined opening and the regulating valve 18 may be kept closed. Thereby, one of raw fuel and steam is supplied to the reforming reaction section 1 or a mixed gas of raw fuel and steam is supplied.

  The subsequent operation is the same as the first operation sequence shown in FIG.

  When the hydrogen generator is operated as described above, in the start-up process, the heating units 4 and 10 are operated to start the temperature raising of the reforming reaction unit 1 and the shift reaction unit 2, and then the reforming reaction unit 1 Until the temperature of the reforming reaction section 1 reaches the second dew point T2 in the state where the temperature is lower than the carbon deposition temperature T3 (area A in the figure), no steam is supplied to the reforming reaction section 1, Only fuel is supplied as purge gas. For this reason, in a state where the temperature of the shift reaction section 2 has not reached the first dew point T1, water vapor does not flow through the shift reaction section 2, but only the raw fuel flows. Therefore, the shift of the shift reaction section 2 is shifted. Water droplets do not adhere to the surface of the catalyst. Further, in a state where the temperature of the reforming reaction unit 1 does not reach the second dew point T2, water vapor does not flow through the reforming reaction unit 1, but only raw fuel flows, and water droplets are also formed on the surface of the reforming catalyst. Will not adhere. Further, while the raw fuel is supplied to the reforming reaction unit 1 without supplying water vapor, the temperature of the reforming reaction unit 1 is lower than the carbon deposition temperature T3. No carbon deposition on the surface of the reforming catalyst due to decomposition of.

  In addition, after the temperature of the reforming reaction unit 1 exceeds the second dew point T2, until the temperature of the reforming reaction unit 1 reaches the carbon deposition temperature T3 (region B in the figure), the reforming reaction unit 1 Is supplied as a purge gas with one of raw fuel and steam or a mixed gas of raw fuel and steam. At this time, only the water vapor, only the raw fuel, or a mixed gas with water vapor flows through the reforming reaction unit 1 and the shift reaction unit 2. Since the dew point T2 or higher and the shift reaction section 2 is higher than the first dew point T1, water droplets do not adhere to the reforming catalyst and the shift catalyst, and no carbon is deposited on the surface of the reforming catalyst.

  In addition, after the temperature of the reforming reaction unit 1 reaches the carbon deposition temperature T3 (region C in the figure), the reforming reaction unit 1 is supplied with a mixed gas of raw fuel and steam. Since the steam reforming reaction proceeds in the reaction section 1, no carbon deposition occurs on the surface of the reforming catalyst, and the reformed gas containing hydrogen produced by the steam reforming reaction is derived from the hydrogen generator. Thus, it can be used for a fuel cell or the like.

Further, after the reforming reaction unit 1 reaches the predetermined reaction temperature T5 and the shift reaction unit 2 reaches the predetermined reaction temperature T4 and shifts to the normal operation process (region E in the figure), the reforming reaction unit 1 A gas mixture of raw fuel and water vapor is supplied to the reforming reaction section 1 in a state where the reaction temperature T5 is maintained and the shift reaction section 2 is maintained at the reaction temperature T4. At this time, first, the steam reforming reaction proceeds in the reforming reaction section 1, and a reformed gas containing hydrogen is generated. This reformed gas is sent to the shift reaction section 2, where most of the CO in the reformed gas is converted to CO ₂ by the aqueous shift reaction in the shift reaction section 2, and the CO concentration in the reformed gas is reduced. This reformed gas is further sent to the CO removing unit 3 where the CO still remaining in the reformed gas is oxidized to CO ₂ by the CO selective oxidation reaction, and the CO concentration in the reformed gas is further reduced. Is done.

  This reformed gas is led out from the hydrogen generator and used as fuel for fuel cells.

  In any of the above operation sequences, when the hydrogen generator is stopped, the control unit 21 performs control to close the adjustment valve 19 and the adjustment valve 20, and supplies air and raw fuel to the heating unit 4. And the control of stopping the operation of the heating units 4 and 10 are performed, the supply of thermal energy to the reforming reaction unit 1 and the shift reaction unit 2 is stopped, and the reforming reaction unit 1 and the shift reaction The temperature of the part 2 is lowered (region F in FIGS. 2 to 4). At the same time, the control unit 21 controls to close the regulating valve 17 and the regulating valve 18 and stops the supply of water vapor and raw fuel to the reforming reaction unit 1.

  When the temperature of the reforming reaction unit 1 and the shift reaction unit 2 is lowered, the temperature of the reforming reaction unit 1 is allowed to reach the carbon deposition temperature T3 before the temperature of the shift reaction unit 2 reaches the first dew point T1. Then, when the control unit 21 recognizes that the temperature of the reforming reaction unit 1 detected by the temperature detector 7 is lower than the carbon deposition temperature T3 and the temperature of the shift reaction unit 2 is equal to or higher than the first dew point T1. The control valve 18 is controlled to open at a predetermined opening, and the raw fuel is supplied without supplying steam to the reforming reaction unit 1.

  When the hydrogen generator is operated as described above, when the temperature of the reforming reaction unit 1 and the shift reaction unit 2 is lowered in order to stop the hydrogen generator, the temperature of the shift reaction unit 2 becomes the first dew point T1. If the temperature of the reforming reaction section 1 is lower than the carbon deposition temperature T3 before reaching the temperature, only the raw fuel is supplied as the purge gas without supplying water vapor to the reforming reaction section 1. At this time, even if the temperature of the reforming reaction section 1 is equal to or lower than the second dew point T2 and the temperature of the shift reaction section 2 is equal to or lower than the first dew point, only the raw fuel is circulated as purge gas and the shift. The adhesion of water droplets on the surface of the catalyst is prevented. Further, since the temperature of the reforming reaction section 1 is lower than the carbon deposition temperature while the raw fuel is circulated as the purge gas, carbon deposition on the surface of the reforming catalyst is also prevented.

It is the schematic which shows an example of embodiment of this invention. It is a graph which shows the 1st driving | operation sequence in this invention. It is a graph which shows the 2nd driving | operation sequence in this invention. It is a graph which shows the 3rd driving | running sequence in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reforming reaction part 2 Transformation reaction part 4 Heating part 10 Heating part T1 1st dew point T2 2nd dew point T3 Carbon deposition temperature T4 Reaction temperature T5 Reaction temperature

Claims (10)

A reforming reaction section that includes a reforming catalyst containing at least Ni or Ru, generates a reformed gas containing hydrogen from a raw fuel gas and steam by a steam reforming reaction, and a CO gas contained in the reformed gas. A method for operating a hydrogen generator comprising a shift reaction section that is reduced by an aqueous shift reaction, and a heating section that heats the reforming reaction section and the shift reaction section,
A startup process in which the reforming reaction section and the shift reaction section are each heated to a predetermined reaction temperature from the state where the operation of the hydrogen generator is stopped, and the reforming reaction section and the shift reaction section are respectively set to the reaction temperature. A normal operation process of supplying a mixed gas containing raw fuel gas and water vapor to the reforming reaction section in a maintained state,
In the start-up process, in the state where the temperature of the shift reaction section is equal to or lower than the first dew point that is the dew point in the shift reaction section when a mixed gas containing raw fuel gas and water vapor is circulated through the shift reaction section. While maintaining the temperature of the reforming reaction section below the carbon deposition temperature, which is the temperature at which carbon deposition on the surface of the reforming catalyst starts when raw fuel is passed through the reforming reaction section, the reforming reaction Supply raw fuel gas without supplying water vapor to the
After the temperature of the reforming reaction section becomes equal to or higher than the carbon deposition temperature, while the temperature of the reforming reaction section and the shift reaction section is raised to a predetermined reaction temperature, the raw fuel gas and A method for operating a hydrogen generator, comprising supplying a mixed gas with water vapor.   The operation method of the hydrogen generator according to claim 1, wherein the first dew point is 62 to 93 ° C. In the start-up process, when the temperature of the reforming reaction part reaches the first dew point, the temperature of the reforming reaction part causes a gas mixture containing raw fuel gas and water vapor to flow through the reforming reaction part When the second dew point, which is the dew point in the reforming reaction part, reaches the second dew point, the reforming reaction part temperature is lower than the carbon deposition temperature after the temperature of the shift reaction part exceeds the first dew point. The operation method of the hydrogen generator according to claim 1 or 2 , wherein at least one of raw fuel and water vapor is supplied to the section. In the start-up process, when the temperature of the reforming reaction unit reaches a predetermined temperature lower than the carbon deposition temperature before the temperature of the shift reaction unit reaches the first dew point, the temperature of the shift reaction unit is the first dew point. The operation method of the hydrogen generator according to claim 3 , wherein the temperature of the reforming reaction section is maintained at a temperature lower than the carbon deposition temperature by intermittently operating the heating section until the temperature reaches the temperature. In the start-up process, after the temperature of the shift reaction section reaches the first dew point, the temperature of the reforming reaction section causes a gas mixture containing raw fuel gas and water vapor to flow through the reforming reaction section. When the second dew point, which is the dew point in the reforming reaction section, reaches the second dew point, the reforming reaction section temperature exceeds the first dew point, and then the reforming reaction section temperature is equal to or lower than the second dew point. When the raw fuel gas is supplied without supplying steam to the reaction section, and the temperature of the reforming reaction section exceeds the second dew point, the reforming reaction section temperature is lower than the carbon deposition temperature, and the reforming section The method for operating a hydrogen generator according to claim 1 or 2 , wherein at least one of raw fuel and water vapor is supplied to the reaction section. The operation method of the hydrogen generator according to any one of claims 1 to 5 , wherein the shift reaction section includes a shift catalyst containing at least copper. The operation method of the hydrogen generator according to any one of claims 1 to 6 , wherein the second dew point is 90 to 100 ° C. The operation method of the hydrogen generator according to any one of claims 1 to 7 , wherein the carbon deposition temperature is 200 to 300 ° C. A reforming reaction section that includes a reforming catalyst containing at least Ni or Ru, generates a reformed gas containing hydrogen from a raw fuel gas and steam by a steam reforming reaction, and a CO gas contained in the reformed gas. A reforming reaction section for reducing by an aqueous shift reaction, a heating section for heating the reforming reaction section and the shift reaction section, and the reforming reaction section and the shift reaction section from a state where the operation of the hydrogen generator is stopped After the start-up process of raising the temperature to a predetermined reaction temperature, raw fuel gas and water vapor are predetermined in the reforming reaction portion while maintaining the reforming reaction portion and the shift reaction portion at the reaction temperature, respectively. A hydrogen generator for producing hydrogen by a normal operation process of supplying a mixed gas containing
When raw fuel is supplied to the reforming reaction section without supplying steam to the reforming reaction section, the temperature of the reforming reaction section is a temperature at which carbon deposition on the surface of the reforming catalyst starts. Before raising the temperature to a certain carbon deposition temperature, the temperature of the shift reaction section is raised to a temperature equal to or higher than the first dew point that is the dew point in the shift reaction section when the mixed gas is supplied to the shift reaction section. A hydrogen generator comprising control means for performing heating control of the reforming reaction section and the shift reaction section by the heating section. The hydrogen generator according to claim 9 , further comprising temperature detection means for detecting temperatures of the reforming reaction section and the shift reaction section.

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