JP2007331985A - Hydrogen generator and fuel cell power generation system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that it is difficult to control respective temperatures of a converting catalyst and an oxidation catalyst to appropriate temperatures, in an integrated type hydrogen generator. <P>SOLUTION: The hydrogen generator is equipped with: an annular first gas flow passage having a reformer 3 for producing a hydrogen-containing gas from a raw material and steam, and a mixed gas flow passage through which a mixed gas of the raw material and steam, supplied to the reformer 3, flows; and an annular second gas flow passage having a converter 4 for reducing the content of carbon monoxide in the hydrogen-containing gas sent out from the reformer 3 and a CO remover 5 for reducing the content of carbon monoxide in the hydrogen-containing gas sent out from the converter 4. Further, in the hydrogen generator, the second gas flow passage has an annular cooling passage, through which the hydrogen-containing gas sent out from the converter 4 flows, between the CO remover 5 and the mixed gas flow passage, and thereby, the hydrogen-containing gas passed through the cooling passage is turned back so as to be introduced into the CO remover 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydrogen generator that generates hydrogen by reacting a hydrocarbon compound and water, and a fuel cell generator that includes a fuel cell that generates electric power using the generated hydrogen.

  The fuel cell power generator generates a hydrogen-containing gas containing hydrogen, carbon dioxide, carbon monoxide, unreacted methane and steam by a steam reforming reaction using a hydrocarbon compound and steam as raw materials. A fuel gas from which carbon monoxide that is harmful to the fuel cell is removed is generated by the carbon oxide reduction unit, and the fuel cell generates power using the fuel gas.

  Various hydrogen generators have been devised and used. For example, in the prior art hydrogen generator 1 shown in FIG. 4, each reactor and the gas flow path to each reactor effectively use heat each other to realize high hydrogen generation efficiency, which is also advantageous in terms of cost. Therefore, it is an integrated hydrogen generator in which each reactor and gas flow path are integrated compactly (for example, refer to Patent Document 1).

  The configuration and operation of this integrated hydrogen generator will be briefly described.

  4 is a burner serving as a heating source for supplying reaction heat necessary for the steam reforming reaction, 3 is a reformer having a reforming catalyst mainly composed of ruthenium, and 4 is copper and zinc. A shifter having a shift catalyst having a main component, 5 a CO remover having an oxidation catalyst having ruthenium as a main component, and 6 an exhaust port for the combustion gas of the burner 2. Hydrocarbons such as city gas and reforming water as raw materials are supplied from a raw material supply port 7 and a reforming water supply port 8, respectively. The reformed water is partially evaporated by receiving reaction heat generated by both catalysts in a narrow tube 9 wound around the shift catalyst and the oxidation catalyst, and then mixed with the raw material in the evaporator 10 consisting of a spiral channel. Sent to. The reformed water which has not evaporated in the evaporator 10 is heated by the combustion gas generated by the burner 2 and the reaction heat generated by the shift catalyst and the oxidation catalyst to completely evaporate, and is mixed with the raw material and sent to the reforming catalyst.

In the reforming catalyst, the raw material and reformed steam become hydrogen-containing gas containing hydrogen, carbon dioxide, carbon monoxide, and unreacted methane and steam. This hydrogen-containing gas is sent to a shifter 4 having a shift catalyst, and carbon monoxide reacts with water vapor by the shift catalyst to become a hydrogen-containing gas whose concentration is reduced to about 1% or less. The hydrogen-containing gas exiting the shift catalyst is mixed with the air supplied from the oxidizing gas supply passage 11 in the mixing chamber 16 and introduced into the CO remover 5 having the oxidation catalyst, and the remaining carbon monoxide is removed by combustion with the oxidation catalyst. Is done. The generated hydrogen-containing gas as the fuel gas is sent from the hydrogen-containing gas outlet 12 to a fuel cell (not shown). In the figure, 13 is a flow port for promoting mixing of the hydrogen-containing gas and air, 14 is a header channel for uniformly supplying the mixed gas of hydrogen-containing gas and air to the oxidation catalyst, and 15 is a hydrogen generator. 1 is a heat insulating material covering 1.
International Publication WO2002 / 098790 Pamphlet

  As described above, a plurality of catalysts are used in the hydrogen generation apparatus, and they have an appropriate operating temperature. For example, the downstream temperature of the transformer 4 is desirably about 200 ° C. from the viewpoint of reaction rate and reaction equilibrium, and the temperature of the CO remover 5 is desirably about 150 ° C. from the viewpoint of selectivity. Specifically, if the temperature downstream of the transformer is greatly below 200 ° C., the reaction rate is remarkably reduced, so that the catalyst cannot work effectively. On the contrary, if the temperature is greatly above 200 ° C., carbon monoxide. This is because the equilibrium concentration of is increased and the reduction of carbon monoxide becomes insufficient. This is because the temperature for effectively selectively oxidizing carbon monoxide without oxidizing hydrogen is in the range of about 140 ° C. to 160 ° C. for the CO remover 5. In addition, in the case of the CO remover 5, if the temperature is too high, the temperature further rises due to self-heating, and the oxidation reaction is excessively promoted, so that the operation of the hydrogen generator must be stopped. is there. Therefore, it is necessary to maintain the hydrogen-containing gas temperature downstream of the transformer 4 at about 200 ° C. and the hydrogen-containing gas temperature at the CO removal unit 5 inlet at about 150 ° C.

  However, in the hydrogen generator described in Patent Document 1, the temperature in the vicinity of the outlet of the shift catalyst is reduced to about 200 ° C. as described above, and the air mixed in the mixing chamber 16 mixed with air is adjacent to the mixing chamber 16. The temperature of the hydrogen-containing gas at the inlet of the CO remover 5 within the restricted mixing chamber space as shown in FIG. 4 is cooled by the reforming water flowing through the reforming water flow path and the water flowing through the evaporator 10. It was difficult to cool to about 150 ° C.

  When the hydrogen-containing gas that has not been cooled to about 150 ° C. is supplied to the oxidation catalyst as it is, there is a possibility of causing excessive promotion of the CO remover 5 as described above. In this case, there is a problem that the downstream portion of the shift catalyst is not effectively used.

  In view of the above problems, an object of the present invention is to provide an integrated hydrogen generator capable of maintaining the temperatures of the transformer and the CO remover at appropriate temperatures.

To achieve the above object, the hydrogen generator of the first aspect of the present invention includes a reformer that generates a hydrogen-containing gas from a raw material and steam by a reforming reaction, and the raw material and steam supplied to the reformer. An annular first gas passage having a mixed gas passage through which the mixed gas flows, and an outer periphery of the first gas passage having a configuration capable of transferring heat to the first gas passage. An annular second gas having a converter for reducing carbon monoxide in the hydrogen-containing gas delivered from the gasifier, and a CO remover for reducing carbon monoxide in the hydrogen-containing gas delivered from the transformer A flow path,
The second gas flow path has an annular cooling path through which the hydrogen-containing gas sent from the transformer flows between the CO remover and the mixed gas flow path, and hydrogen that has exited the cooling path. The contained gas is folded and introduced into the CO remover.

  The hydrogen generator of the second aspect of the present invention further includes an oxidizing gas supply path for supplying an oxidizing gas to the hydrogen-containing gas sent from the transformer, and an outlet of the oxidizing gas supply path is an inlet of the cooling path. It is provided in the vicinity.

  The hydrogen generator of the third aspect of the present invention includes an oxidizing gas supply path for supplying an oxidizing gas to the hydrogen-containing gas sent from the transformer, and the second gas flow path includes the hydrogen-containing gas and the hydrogen-containing gas. It has an annular mixing chamber in which the oxidizing gas is mixed, and has a communication port for the mixed gas in the mixing chamber to gather and diffuse into the annular cooling passage.

  The hydrogen generator of the fourth aspect of the present invention includes an oxidizing gas supply path for supplying an oxidizing gas to the hydrogen-containing gas sent from the transformer, and an outlet of the oxidizing gas supply path is in the vicinity of the communication port. It is provided in.

  A fuel cell power generator of the fifth aspect of the present invention includes the hydrogen generator of the present invention and a fuel cell that generates power using a hydrogen-containing gas supplied from the hydrogen generator.

  According to the present invention, it is possible to provide an integrated hydrogen generator capable of adjusting the temperatures of the shift catalyst of the shift converter and the oxidation catalyst of the CO remover to an appropriate temperature within a limited space of the integrated hydrogen generator.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a schematic configuration diagram of the hydrogen generator 17 in the first embodiment. In FIG. 1, the same components as those of the above-described prior art hydrogen generator 1 are denoted by the same reference numerals, and the operation for generating the fuel gas is also the same, so that the description thereof is omitted.

  In FIG. 1, reference numeral 18 denotes an inner cylinder of the oxidation catalyst, which is disposed coaxially with and separated from an outer cylinder 19 serving as a cooling surface of the evaporator 10 to form a cooling path 20 therebetween. Further, the oxidizing gas supply path 21 is installed with its outlet extending to the vicinity of the cooling path 20.

  In addition, the first gas flow path of the present invention includes a reformer 3 having a reforming catalyst provided in an annular shape, and an annular evaporation that is a mixed gas flow path of the present invention through which a mixed gas of a raw material and water vapor flows. And a vessel 10. On the other hand, the second gas flow path of the present invention is provided so as to cover the outer periphery of the first gas flow path, and a shift catalyst to which the hydrogen-containing gas sent from the reformer 3 is fed back is provided. And a CO remover 5 having an oxidation catalyst to which a hydrogen-containing gas fed from the transformer 4 is supplied. The second gas flow path has the cooling passage 20 through which the hydrogen-containing gas sent from the transformer 4 flows between the CO remover 5 and the evaporator 10, where the hydrogen-containing gas is evaporated. Heat is exchanged with non-evaporated reforming water flowing through the vessel 10 and cooled. The hydrogen-containing gas exiting the cooling path 20 is turned back and supplied to the CO remover 5.

  Hereinafter, the operation of the hydrogen generator 17 having this configuration will be described. As described above, since the temperature downstream of the shift catalyst is about 200 ° C., the hydrogen generator 17 of the present embodiment is also configured such that the temperature downstream of the shift catalyst is 200 ° C. The air as the oxidizing gas supplied from the oxidizing gas supply path 21 and the hydrogen-containing gas are mixed in the mixing chamber 16 and then enter the cooling path 20.

  In the cooling passage 20, the hydrogen-containing gas gives heat to the unevaporated reforming water and the raw material flowing in the evaporator 10, and is cooled to about 150 ° C. After exiting the cooling path 20, the flow is reversed and supplied to the CO remover 5, and the remaining carbon monoxide is selectively oxidized to form a hydrogen-containing gas having a CO concentration of 10 ppm or less. 12 flows out.

  As described above, after the oxidizing gas is mixed with the hydrogen-containing gas sent from the transformer 4 as in the conventional integrated hydrogen generator, the gas is not supplied to the CO remover as it is, but instead of the CO remover 5. By providing a cooling path for cooling the hydrogen-containing gas between the evaporator 10 located on the side, the post-transformation is performed in a limited space of an integrated hydrogen generator that is required to be compact. It becomes possible to set it as the structure which can cool hydrogen containing gas to desired temperature (150 degreeC).

  In order to adjust the temperature of the hydrogen-containing gas at the outlet of the cooling path 20 to about 150 ° C. according to various configurations and specifications of the apparatus, the outer cylinder 19 of the evaporator 10 and the inner cylinder 18 of the oxidation catalyst are used. Adjust the interval. Specifically, if this interval is narrowed, the heat transfer coefficient on the hydrogen-containing gas side increases, so the amount of heat released from the hydrogen-containing gas increases, and the temperature of the hydrogen-containing gas at the outlet of the cooling path 20 can be lowered. Conversely, in order to increase the hydrogen-containing gas at the outlet of the cooling path 20, the interval may be increased.

  As described above, the hydrogen generator of the present embodiment can set the temperature downstream of the shift catalyst of the shift converter 4 and the temperature of the oxidation catalyst of the CO remover 5 to temperatures suitable for each, so that each catalyst can be used effectively. can do.

  Further, as described above, the oxidizing gas supply passage 21 is installed with the outlet of the oxidizing gas extending to the vicinity of the cooling passage 20, so that the supplied air is transformed into a copper-zinc system compared to the conventional hydrogen generator. The possibility of causing catalyst deterioration due to touching the downstream end of the catalyst may be reduced, or the amount of hydrogen delivered from the hydrogen-containing gas outlet 12 may be reduced due to the oxidation reaction of hydrogen due to contact of the air with the downstream end of the precious metal-based conversion catalyst Is reduced.

Further, in the fuel cell power generator using the hydrogen generator of the present embodiment, the hydrogen-containing gas supplied from the hydrogen generator 17 is supplied to the anode of the fuel cell 30 as shown in FIG. Electricity is generated by an electrochemical reaction between hydrogen in the hydrogen-containing gas and oxygen in the oxidant gas supplied to the cathode.
(Embodiment 2)
FIG. 3 is a schematic configuration diagram of the hydrogen generator 22 according to the second embodiment. In FIG. 3, the same components as those of the hydrogen generator 17 of the first embodiment are denoted by the same reference numerals, and the operation for generating the hydrogen-containing gas is also the same, so that the description thereof is omitted.

  In FIG. 3, in the second embodiment, the mixed gas in the annular mixing chamber 16 in which the hydrogen-containing gas sent from the transformer 4 and air are mixed together is introduced into the annular cooling passage 20 and diffused. There is a communication port 23 for this purpose. The communication port 23 is provided in the vicinity of the outlet of the oxidizing gas supply path 21. This can further reduce the possibility that air will come into contact with the shift catalyst. Hydrogen oxidation in the case of a noble metal shift catalyst may reduce the amount of hydrogen, or oxidation deterioration of the catalyst in the case of a copper-zinc shift catalyst. Can be obtained.

  The hydrogen generator of the present invention is an integrated hydrogen generator capable of controlling the transformer and the CO remover to an optimum temperature in a limited space, such as a domestic fuel cell power generator using this device. Useful for.

Schematic configuration diagram of a hydrogen generator in Embodiment 1 according to the present invention 1 is a schematic configuration diagram of a fuel cell power generator according to Embodiment 1 of the present invention. Schematic configuration diagram of a hydrogen generator in Embodiment 2 according to the present invention Schematic configuration diagram of a conventional hydrogen generator

Explanation of symbols

1, 17, 22 Hydrogen generator 2 Burner 3 Reformer 4 Transformer 5 CO remover 6 Exhaust port 7 Raw material supply port 8 Reformed water supply port 9 Narrow tube 10 Evaporator 11 Oxidation gas supply path 12 Hydrogen-containing gas outlet 13 Distribution port 14 Header flow path 15 Heat insulating material 16 Mixing chamber 18 Inner cylinder 19 Outer cylinder 20 Cooling path 21 Oxidizing gas supply path 23 Communication port 30 Fuel cell

Claims (5)

An annular first gas flow path having a reformer that generates a hydrogen-containing gas from a raw material and steam by a reforming reaction, and a mixed gas flow path through which a mixed gas of the raw material and steam supplied to the reformer flows When,
A transformer provided on the outer periphery of the first gas flow path in a configuration capable of transferring heat to the first gas flow path, and for reducing carbon monoxide in the hydrogen-containing gas delivered from the reformer; and An annular second gas flow path having a CO remover for reducing carbon monoxide in the hydrogen-containing gas delivered from the transformer,
The second gas flow path has an annular cooling path through which the hydrogen-containing gas sent from the transformer flows between the CO remover and the mixed gas flow path, and hydrogen that has exited the cooling path. A hydrogen generating apparatus, wherein the gas contained is folded back and introduced into the CO remover. An oxidizing gas supply path for supplying an oxidizing gas to the hydrogen-containing gas delivered from the transformer;
2. The hydrogen generator according to claim 1, wherein an outlet of the oxidizing gas supply path is provided in the vicinity of the inlet of the cooling path. An oxidizing gas supply path for supplying an oxidizing gas to the hydrogen-containing gas delivered from the transformer;
The second gas flow path has an annular mixing chamber in which the hydrogen-containing gas and the oxidizing gas are mixed, and a communication port through which the mixed gas in the mixing chamber collects and diffuses into the annular cooling passage The hydrogen generator according to claim 1, comprising: An oxidizing gas supply path for supplying an oxidizing gas to the hydrogen-containing gas delivered from the transformer;
2. The hydrogen generator according to claim 1, wherein an outlet of the oxidizing gas supply path is provided in the vicinity of the communication port.   A fuel cell power generator comprising: the hydrogen generator according to claim 1; and a fuel cell that generates power using a hydrogen-containing gas supplied from the hydrogen generator.

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