JP2008056543A - Hydrogen manufacturing apparatus and fuel battery system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen manufacturing apparatus which can sufficiently reduce the temperature of the hydrogen-containing gas fed to a CO remover by evaporating the liquid in the upstream in the evaporator in a multi-concentric cylinder type hydrogen generator in which the evaporator is installed between the combustion gas path and the converter with partitions in between and the flow of water in the evaporator runs opposite to the flow of the combustion gas in the combustion gas path. <P>SOLUTION: The heat conductivity of a first partition 21 arranged between combustion gas path 11 and evaporator 4a is made smaller than the heat conductivity of a second partition 22 arranged between the evaporator 4a and conversion catalyst 6a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention reliably generates steam when a raw material such as hydrocarbon is subjected to steam reforming reaction with steam and a reformer that reduces carbon monoxide by a shift reaction is provided to generate hydrogen-rich reformed gas. In addition, the present invention relates to a hydrogen generator that uniformly heats the catalyst layer of the transformer, and a fuel cell system using the hydrogen generator.

  In a fuel cell power generation system or the like, a hydrogen production apparatus that uses a hydrocarbon or the like as a raw material and generates a reformed gas containing hydrogen as a main component by causing the raw material to undergo a steam reforming reaction is used.

  An example of a hydrogen production apparatus for steam reforming raw materials such as hydrocarbons is shown in FIG. In this hydrogen production apparatus, the reformer 1 filled with the reforming catalyst 1a, the shifter 6 filled with the shift catalyst 6a, and the CO remover 9 filled with the oxidation catalyst 9a are integrated into a concentric circle. Characterized by the structure. The raw material required for the steam reforming reaction is supplied from the raw material supplier 3, and water is supplied from the water supply unit 2 to the evaporator 4a together with the raw material in a liquid state, and the high-temperature combustion gas generated in the combustor 5 flows Water heated by the combustion gas in the gas flow path and supplied to the evaporator 4a becomes steam. When this mixed gas of raw material and steam is supplied to the reformer 1, it becomes a hydrogen-rich reformed gas through the reformer 1 by a steam reforming reaction. At this time, since the steam reforming reaction is an endothermic reaction, it is necessary to heat from the outside to a temperature necessary for the steam reforming reaction. Therefore, a combustor 5 is provided as a heating source, and the gas combusted there heats the reformer 1 with sensible heat from the combustion gas passage 11. The reformed gas is converted to hydrogen by a shift reaction in a temperature range of 200 ° C. to 400 ° C. in the transformer 6 to reduce carbon monoxide contained in the reformed gas to a specific amount. Since this modification reaction is an exothermic reaction, heating is not necessary when generating electricity with a fuel cell, but at the time of start-up, a heater 6c may be provided until the temperature is reached for the modification reaction. . The reformed gas in which the carbon monoxide is reduced to a specific amount passes through the transformer 6 and is then oxidized with the air supplied from the air supply unit 8 by the CO remover 9 in the temperature range of 100 ° C. to 150 ° C. Thus, carbon monoxide is oxidized to carbon dioxide, and the concentration of carbon monoxide in the gas is further reduced. Since this oxidation reaction is an exothermic reaction, heating is not required when power is generated by the fuel cell, but at the time of start-up, a heater 9c may be provided until the temperature reaches the temperature required for the oxidation reaction. .

Further, as a feature of the above hydrogen production apparatus, the reaction units 1, 6, 9 and the evaporator 4a are concentrically arranged in order to effectively use the heat generated from the reaction units 1, 6, 9 and improve the heat conversion efficiency. In addition, it has an integrated structure of multiple cylinders. In order to heat the reaction part 1 and the evaporator 4a, the combustion gas flow path 11 is provided inside, and the heat exchange property between the combustion gas in the combustion gas flow path 11 and water or water vapor in the evaporator 4a is improved. Therefore, the flow direction of the combustion gas is opposed to the flow direction of the water or water vapor. Also, a transformer 4a and a CO remover 9 are provided outside the evaporator 4a. The heat generated by the transformation reaction in the transformer 4a and the hydrogen-containing gas sent from the transformer 4a and introduced into the CO remover 9 are provided. It is evaporated by using heat (see, for example, Patent Document 1).
International Publication No. 02/098790 Pamphlet

  However, in the above conventional hydrogen generator, the flow of the combustion gas in the combustion gas passage 11 and the flow of water or water vapor in the evaporator 4a are opposed to each other, so that the combustion gas upstream from the combustion gas passage 11a If heat is transferred excessively to the water vaporizer on the downstream side of the evaporator 4a, sufficient heat is not transmitted to evaporate the water on the upstream side of the evaporator 4a, and the liquid water partially passes through the flow path of the evaporator 4a. As a result, the flow rate of the raw material flow is distributed, so that the raw material flow rate supplied to the reformer 1 becomes non-uniform, the reforming reaction becomes non-uniform, and a predetermined hydrogen generation amount cannot be obtained. There was a problem.

  Further, the temperature stability of the shift catalyst 6a that generates heat due to the shift reaction is ensured, and the hydrogen-containing gas of 200 ° C. or more sent from the shift converter 6 is brought to a temperature of about 150 ° C. before being introduced into the CO remover 9. If not sufficiently reduced, the CO remover 9 becomes high in temperature and the methanation reaction may proceed to cause thermal runaway.

  The present invention has been made in view of the above points. A reformer that converts a raw material into a hydrogen-containing gas by a steam reforming reaction, a shifter, a CO remover, and water for performing steam reforming are converted into steam. An evaporator is provided, and the evaporator is provided between the combustion gas flow path and the transformer via a partition wall, and the flow of water or water vapor in the evaporator and the combustion gas in the combustion gas flow path are opposed to each other. In the multi-cylindrical hydrogen generator, liquid water is sufficiently evaporated without accumulating upstream in the evaporator, ensuring the temperature stability of the shift catalyst 6a that generates heat due to shift reaction, and containing hydrogen introduced into the CO remover An object of the present invention is to provide a hydrogen generator capable of sufficiently reducing the temperature of a gas, and a fuel cell system including the same.

  In order to solve the above problems, a hydrogen generator of the first aspect of the present invention includes a reformer that generates a hydrogen-containing gas by a reforming reaction of a raw material and steam, and a combustor for heating the reformer. A combustion gas flow path through which combustion gas delivered from the combustor flows, an evaporator for generating the water vapor by heat from the combustion gas outside the combustion gas flow path, and outside the evaporator A converter for reducing carbon monoxide in the hydrogen-containing gas delivered from the reformer by a shift reaction, and a CO for applying for low carbon monoxide from the reformer by an oxidation reaction. A hydrogen generator configured to oppose a flow of combustion gas flowing through the combustion gas flow path and a flow of water vapor flowing through the evaporator, wherein the combustion gas flow path and the evaporator Gold constituting the first partition between Is characterized by a low thermal conductivity than the metal constituting the second partition between said transformer and said evaporator.

  Further, in the hydrogen generator of the second aspect of the present invention, the thermal conductivity of the metal constituting the first partition and the metal constituting the second partition is 10 [w / m ° C.] or more, The difference in thermal conductivity between the metal constituting the partition and the metal constituting the second partition is 2 [w / m ° C.] or more.

  In the hydrogen generator of the third aspect of the present invention, the metal constituting the first partition has a thermal conductivity of 10 [w / m ° C.] or more and 20 [w / m ° C.] or less, and the second partition It is characterized in that the thermal conductivity of the constituent metal is 22 [w / m ° C.] or more.

  In the hydrogen generating apparatus of the fourth aspect of the present invention, the metal constituting the first partition is austenitic stainless steel, and the metal constituting the second partition is ferrite stainless.

  In the hydrogen generator of the fifth aspect of the present invention, the metal constituting the first partition is C: 0.02 to 0.10% by mass, Si: 0 to 2.5% by mass, Mn: 0 to 2.0 mass%, P: 0 to 0.04 mass%, S: 0 to 0.02 mass%, Ni: 7 to 12 mass% or less, Cr: 15 to 25 mass%, the balance being substantially Fe The metal having the composition and constituting the second partition wall is C: 0 to 0.02 mass%, Si: 0 to 2.5 mass%, Mn: 0 to 2.0 mass%, P: 0 to 0. 0.04% by mass, S: 0 to 0.02% by mass, Ni: 0 to 0.6% by mass, Cr: 15 to 25% by mass, and the balance being substantially Fe composition.

  A fuel cell system according to a sixth aspect of the present invention includes the hydrogen generators according to the first to fifth aspects of the present invention, and a fuel cell that generates power using a hydrogen-containing gas supplied from the hydrogen generator. Features.

  According to the hydrogen generator of the present invention, liquid water is sufficiently evaporated without accumulating upstream in the evaporator, and the temperature of the hydrogen-containing gas introduced into the CO remover can be sufficiently reduced. Become.

  FIG. 2 is a schematic diagram illustrating an example of a hydrogen generator according to an embodiment of the present invention.

  The combustor 5 is disposed in the center, and a combustion gas flow path 11, a first partition 21, an evaporator 4a, a second partition 22, a shift catalyst 6a, and an oxidation catalyst 9a are sequentially provided outward. The first partition 21 is made of a metal material having a lower thermal conductivity than the second partition 22. The water supplied from the water supply unit 2 and the raw material gas supplied from the raw material supply device 3 are sent to the evaporator 4a to become a mixture of water vapor and the raw material gas and are reformed arranged downstream of the evaporator 4a. It passes through the vessel 1, the transformer 5, and the CO remover 9 and sequentially flows as reformed gas. The flow direction of the combustion gas in the combustion gas channel 11 and the flow direction of the water in the evaporator 4a are opposed to each other. Liquid phase water is supplied to the evaporator 4a, and heat is transferred from the combustion gas flow which is a counter flow, evaporates downstream to become water vapor, and is supplied to the reforming catalyst 1a as a mixture with the raw material gas. .

  Heat transfer from the combustion gas to the evaporator 4a is performed through the first partition 21, but since the thermal conductivity of the first partition 21 is small, the upstream of the combustion gas flow path 4a flowing from the outlet of the combustor 5 is used. The amount of heat transfer from the high-temperature combustion gas is suppressed, the temperature of the combustion gas on the downstream side becomes high, and the liquid phase water that has flowed into the evaporator 4a can be sufficiently evaporated. Therefore, the liquid flowing into the evaporator 4a closes the flow path, and the flow of the raw material gas can be biased to prevent the reforming reaction from becoming nonuniform, resulting in a uniform and stable reforming reaction. Can be stabilized. Further, since the transformer 6 and the CO remover 9 are provided outside the evaporator 4a, when the water flowing into the evaporator 4a does not evaporate quickly, the transformer 6 and the CO remover 9 are in the liquid phase. Since it is cooled by water, the temperature drops, the temperature difference of the catalyst layer increases, the catalytic reaction becomes insufficient, and carbon monoxide in the reformed gas cannot be reduced stably, but the liquid phase that has flowed into the evaporator 4a Since water can be quickly evaporated, the temperature distribution due to partial cooling of the transformer 6 and the CO remover 9 can also be reduced, and carbon monoxide in the reformed gas can be stably reduced. .

  A second partition 22 is provided outside the evaporator 4a, a shift catalyst 6a is provided outside the second partition 22, and an oxidation catalyst 9a is provided in communication with the downstream side of the shift catalyst 6a. ing. The reaction of the shifter is a CO water shift reaction, the inlet temperature of the shifter catalyst 6a is approximately 300 ° C., the outlet temperature is approximately 200 ° C., and the shift reaction in the shifter 6 is an exothermic reaction. 6 needs to be radiated to maintain temperature stability. Furthermore, the inlet temperature of the CO remover 9a is about 150 ° C., and the temperature of the hydrogen-containing gas having a temperature of about 200 ° C. sent from the transformer 6 needs to be lowered to about 150 ° C. Here, by providing a heat exchange section for reducing the temperature of the reformed gas outside the shifter 6 and between the outlet of the shift catalyst 6a and the inlet of the CO remover 9a, the temperature can be lowered to a predetermined oxidation inlet temperature. Although it is possible, it is necessary to newly provide a heat exchange part, and the apparatus cannot be made compact.

  Therefore, by providing the evaporator 4a outside the shift converter 6 as in the present embodiment, the shift catalyst heat is transferred from the shift catalyst 6a to the evaporator 4a through the second partition wall 22, so that the second By increasing the thermal conductivity of the partition wall 22, the amount of heat transferred from the shift catalyst 6a to the evaporator 4a can be increased, and the outlet temperature of the shift catalyst 6a can be maintained at a temperature of about 200 ° C. The temperature of the hydrogen-containing gas introduced into the CO remover 6 can be lowered to about 150 ° C., CO can be reduced in the CO remover 9, and the apparatus is not required to provide a heat exchange part. Can be compact.

  In addition, as a metal which comprises the said 1st partition 21 and the 2nd partition 22, thermal conductivity is 10 [w / m degree C] or more, for example, the metal which comprises the 1st partition 21, and 2nd The difference in the thermal conductivity of the metal constituting the partition wall 22 is preferably 2 [w / m ° C.] or more, more specifically, the thermal conductivity of the metal constituting the first partition wall is 10 [w / M ° C.] or more and 20 [w / m ° C.] or less, and the thermal conductivity of the metal constituting the second partition wall is preferably 22 [w / m ° C.] or more.

  In the present embodiment, in consideration of heat resistance and corrosion resistance, the first partition wall 21 is made of austenitic stainless steel, and the second partition wall 22 is made of ferrite stainless steel. In addition, as a metal material used for each said partition, the metal which comprises a 1st partition is C: 0.02-0.10 mass%, Si: 0-2.5 mass%, Mn: 0 2.0 mass%, P: 0 to 0.04 mass%, S: 0 to 0.02 mass%, Ni: 7 to 12 mass% or less, Cr: 15 to 25 mass%, the balance being substantially Fe The metal which has a composition and comprises the 2nd partition is C: 0-0.02 mass%, Si: 0-2.5 mass%, Mn: 0-2.0 mass%, P: 0-0. 04 mass%, S: 0 to 0.02 mass%, Ni: 0 to 0.6 mass%, Cr: 15 to 25 mass%, and the balance may substantially have a composition of Fe.

  As described above, the thermal conductivity of the first partition wall 21 provided between the combustion gas flow path 11 and the evaporator 4a is small, and the second partition wall 22 provided between the evaporator 4a and the shift catalyst 6a. By increasing the thermal conductivity, liquid water is sufficiently evaporated without accumulating upstream in the evaporator 4a, and the temperature stability of the shift catalyst 6a that generates heat by the shift reaction is maintained and introduced into the CO remover. It is possible to sufficiently reduce the temperature of the hydrogen-containing gas.

  The hydrogen generator according to the present invention is sufficiently evaporated without accumulating liquid water upstream in the evaporator, and the temperature of the hydrogen-containing gas introduced into the CO remover can be sufficiently reduced. Therefore, it is useful as a hydrogen generator for a household fuel cell cogeneration system.

Diagram showing a conventional hydrogen production system Sectional drawing which shows the principal part which shows embodiment of the hydrogen production apparatus of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reformer 1a Reforming catalyst 1b Reforming temperature detection part 2 Water supply device 3 Raw material supply device 4a Evaporator 5 Combustor 6 Transformation device 6a Transformation catalyst 6b Transformation temperature detector 6c Heater 7 Heat exchanger 8 Air supply device 9 CO remover 9a Oxidation catalyst 9b Temperature detector 9c Heater 10 Combustion fan 11 Combustion gas flow path 21 First partition 22 Second partition

Claims (6)

A reformer that generates a hydrogen-containing gas by a reforming reaction of a raw material and steam, a combustor for heating the reformer, a combustion gas passage through which a combustion gas sent from the combustor flows, and An evaporator for generating the water vapor by heat from the combustion gas outside the combustion gas flow path, and a carbon monoxide in the hydrogen-containing gas sent from the reformer to the outside of the evaporator And a CO remover for reducing the carbon monoxide of the hydrogen-containing gas delivered from the transformer by an oxidation reaction, the flow of the combustion gas flowing through the combustion gas passage and the evaporation A hydrogen generator configured to oppose the flow of water vapor flowing through the vessel, wherein the metal constituting the first partition between the combustion gas flow path and the evaporator is the evaporator and the transformation Constitutes a second partition wall Hydrogen generator, wherein the lower thermal conductivity than the genus. The metal constituting the first partition and the metal constituting the second partition have a thermal conductivity of 10 [w / m ° C.] or more, and the metal constituting the first partition and the second 2. The hydrogen generator according to claim 1, wherein the difference in thermal conductivity of the metal constituting the partition wall is 2 [w / m ° C.] or more. The metal constituting the first partition has a thermal conductivity of 10 [w / m ° C.] or more and 20 [w / m ° C.] or less, and the metal constituting the second partition has a thermal conductivity of 22 [w / M ° C.] or more. 2. The hydrogen generating apparatus according to claim 1, wherein the metal constituting the first partition is austenitic stainless steel, and the metal constituting the second partition is ferritic stainless steel. The metal constituting the first partition is C: 0.02 to 0.10% by mass, Si: 0 to 2.5% by mass, Mn: 0 to 2.0% by mass, P: 0 to 0.04%. Mass%, S: 0 to 0.02 mass%, Ni: 7 to 12% by mass or less, Cr: 15 to 25 mass%, the balance substantially having a composition of Fe, and the metal constituting the second partition wall Are C: 0-0.02 mass%, Si: 0-2.5 mass%, Mn: 0-2.0 mass%, P: 0-0.04 mass%, S: 0-0.02 mass%. 2. The hydrogen generator according to claim 1, wherein Ni is 0 to 0.6 mass%, Cr is 15 to 25 mass%, and the balance is substantially composed of Fe. A fuel cell system comprising the hydrogen generator according to claim 1 and a fuel cell that generates electric power using a hydrogen-containing gas supplied from the hydrogen generator.

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