JP2005179082A - Hydrogen producing apparatus, fuel cell system and method for driving the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress oxidation deterioration of a catalyst in a hydrogen producing apparatus without purging when a fuel cell system or a hydrogen producing apparatus stops. <P>SOLUTION: In the method for driving a hydrogen producing apparatus which produces gas containing hydrogen by using reform reaction from a source material for hydrogen production and which has at least a reformer, or in the method for driving a fuel cell system having a hydrogen producing apparatus and a fuel cell for electric power generation by using the hydrogen-containing gas obtained from the hydrogen producing apparatus, the hydrogen-containing gas in the downstream side of the reformer is stored in a storing means in the hydrogen producing apparatus during producing hydrogen. When the apparatus is stopped, the line including the reformer and the storing means is changed into a closed space and the hydrogen-containing gas stored in the storing means is released. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hydrogen production apparatus for producing hydrogen from a raw material for hydrogen production such as kerosene, and to a fuel cell system using a hydrogen-containing gas produced by the hydrogen production apparatus as a fuel.

  Development of fuel cells has been actively promoted as a power generation system with high energy utilization efficiency. Among them, the polymer electrolyte fuel cell is particularly attracting attention because of its high power density and ease of handling.

  Since a fuel cell generates power by an electrochemical reaction between hydrogen and oxygen, it is essential to establish a hydrogen supply means. As one of the methods, there is a method of producing hydrogen by reforming a raw material for hydrogen production such as a hydrocarbon fuel, and a method using pure hydrogen in that a hydrocarbon fuel supply system has already been socially established. More advantageous.

  Examples of the hydrocarbon fuel include city gas, gasoline, kerosene, and light oil. Liquid fuels such as gasoline, kerosene, and light oil are attracting attention as fuel cells because they are easy to handle, store and transport, and are inexpensive. In order to use these raw materials for hydrogen production in a fuel cell, it is necessary to produce hydrogen from hydrocarbons. For this purpose, a hydrogen production apparatus including at least a reformer is used.

  In a hydrogen production apparatus, for example, a hydrocarbon is reacted with water in a reformer to mainly decompose it into carbon monoxide and hydrogen, and then a majority of carbon monoxide is reacted with water in a shift reactor to produce hydrogen and carbon dioxide. In the selective oxidation reactor, a trace amount of residual carbon monoxide is finally reacted with oxygen to form carbon dioxide. Further, since sulfur becomes a poisoning substance such as a reforming catalyst, a desulfurizer for removing sulfur in the hydrocarbon fuel is often provided.

  When such a fuel cell system is stopped, purging with an inert gas typified by nitrogen has been performed for the purpose of protecting a catalyst present in the hydrogen production apparatus. However, space was required for storage of nitrogen, and it took time and effort to supply and manage it.

An object of the present invention is to provide a purge means for a fuel cell power generation system that can overcome such a situation, can easily supply an inert gas used for purging the fuel cell system, and has an unnecessary high maintainability such as replacement of members. Patent Document 1 discloses a fuel cell power generation system that uses a reproducible oxygen removing means for removing oxygen contained in air.
JP 2002-280038 A

  In the technique described in Patent Document 1, although an inert gas cylinder or the like is not required, oxygen is reduced by sending air from an air supply blower to a deoxygenation column (oxygen removing means), and purging is performed using this. ing. In other words, the purge is still being performed, and it cannot be said that the stop operation is simple, and it is necessary to continue the operation of the air supply blower even after the end of power generation.

  An object of the present invention is to provide a fuel cell system and an operation method thereof capable of suppressing oxidation deterioration of a catalyst in a hydrogen production apparatus without performing a purge operation when the fuel cell system is stopped.

  Another object of the present invention is to provide a hydrogen production apparatus and a method for operating the hydrogen production apparatus that can suppress oxidative deterioration of a catalyst in the hydrogen production apparatus without performing a purge operation when the hydrogen production apparatus is stopped.

According to the present invention, in a method for operating a hydrogen production apparatus having at least a reformer, for producing a gas containing hydrogen using a reforming reaction from a raw material for hydrogen production,
During hydrogen production, the hydrogen-containing gas downstream of the reformer is stored in the storage means,
Provided is a method for operating a hydrogen production apparatus, characterized in that when stopping, a line including a reformer and the storage means is closed, and the hydrogen-containing gas stored in the storage means is released.

  The storage means preferably has a liquid seal structure that seals between the hydrogen-containing gas and the atmosphere with a liquid.

According to the present invention, in a hydrogen production apparatus having at least a reformer for producing a gas containing hydrogen using a reforming reaction from a raw material for hydrogen production,
Having storage means for storing the hydrogen-containing gas downstream of the reformer;
There is provided a hydrogen production apparatus having means for making a line including a reformer and the storage means into a closed space.

  The storage means preferably has a liquid seal structure that seals between the hydrogen-containing gas and the atmosphere with a liquid.

According to the present invention, a hydrogen production apparatus having at least a reformer and a hydrogen-containing gas obtained from the hydrogen production apparatus for producing a gas containing hydrogen from a raw material for hydrogen production using a reforming reaction. In a method of operating a fuel cell system having a fuel cell for generating power,
Storing hydrogen-containing gas downstream of the reformer in the storage means during hydrogen production by the hydrogen production apparatus;
When stopping the fuel cell system, the line including the reformer and the storage means is closed, and the hydrogen-containing gas stored in the storage means is discharged. Is provided.

  The storage means preferably has a liquid seal structure that seals between the hydrogen-containing gas and the atmosphere with a liquid.

According to the present invention, a hydrogen production apparatus having at least a reformer and a hydrogen-containing gas obtained from the hydrogen production apparatus for producing a gas containing hydrogen from a raw material for hydrogen production using a reforming reaction. In a fuel cell system having a fuel cell for generating power,
Having storage means for storing the hydrogen-containing gas downstream of the reformer;
There is provided a fuel cell system having means for making a reformer and a line including the storage means into a closed space.

  The storage means preferably has a liquid seal structure that seals between the hydrogen-containing gas and the atmosphere with a liquid.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell system which makes it possible to suppress the oxidative degradation of the catalyst in a hydrogen production apparatus, without performing purge operation at the time of a fuel cell system stop, and its operating method are provided.

  In addition, according to the present invention, there are provided a hydrogen production apparatus and an operation method thereof capable of suppressing oxidative deterioration of a catalyst in the hydrogen production apparatus without performing a purge operation when the hydrogen production apparatus is stopped.

  When the hydrogen production apparatus or the fuel cell system is stopped, if the hydrogen production apparatus is shut off from the atmosphere without purging, the internal pressure of the hydrogen production apparatus becomes negative as the temperature of the hydrogen production apparatus decreases. There is a possibility that air flows from the atmosphere into the negative pressure portion and the catalyst provided in the hydrogen production apparatus is oxidized and deteriorated. There is also a risk that the equipment will be damaged by the negative pressure. In order to prevent such a situation, in the present invention, a hydrogen-containing gas is stored at the time of hydrogen production, and negative pressure is prevented and oxidative deterioration is prevented by releasing the hydrogen-containing gas from the storage means at the time of stoppage.

[Hydrogen production equipment]
The hydrogen production apparatus is an apparatus that produces a gas containing hydrogen from a raw material for hydrogen production. The product gas obtained by the hydrogen production apparatus is used by being supplied to the anode chamber of the fuel cell, for example. In addition, the product gas can be stored as needed and used to supply automobiles or the like at a hydrogen station.

  In order to produce a hydrogen-containing gas by reforming a raw material for producing hydrogen by a reforming reaction, the hydrogen production apparatus includes at least a reformer. A shift reactor can also be provided downstream of the reformer to reduce the carbon monoxide concentration. When used for a polymer electrolyte fuel cell or the like, it is preferable to provide a selective oxidation reactor downstream of the shift reactor in order to further reduce the carbon monoxide concentration. Further, if necessary, a desulfurizer for reducing the concentration of sulfur in the raw material for hydrogen production can be provided upstream of the reformer.

[Reformer]
In the reformer, water (steam) and / or oxygen is reacted with a raw material for hydrogen production to produce a reformed gas containing hydrogen. In this apparatus, the raw material for hydrogen production is mainly decomposed into hydrogen and carbon monoxide. Usually, carbon dioxide and methane are also contained in the cracked gas. Examples of the reforming reaction include a steam reforming reaction, an autothermal reforming reaction, and a partial oxidation reaction.

The steam reforming reaction is a reaction between steam and a raw material for producing hydrogen. However, since it involves a large endotherm, heating from the outside is usually required. Usually, the reaction is carried out in the presence of a metal catalyst typified by a Group VIII metal such as nickel, cobalt, iron, ruthenium, rhodium, iridium and platinum. The reaction temperature can be 450 ° C to 900 ° C, preferably 500 ° C to 850 ° C, more preferably 550 ° C to 800 ° C. The amount of steam introduced into the reaction system is defined as the ratio of the number of moles of water molecules to the number of moles of carbon atoms contained in the raw material for hydrogen production (steam / carbon ratio), and this value is preferably 0.5-10. Preferably it is 1-7, More preferably, it is 2-5. When the raw material for hydrogen production is liquid, the space velocity (LHSV) at this time is A / B when the flow rate in the liquid state of the raw material for hydrogen production is A (L / h) and the volume of the catalyst layer is B (L). This value is preferably set in the range of 0.05 to 20 h ⁻¹ , more preferably 0.1 to 10 h ⁻¹ , and still more preferably 0.2 to 5 h ⁻¹ .

  Autothermal reforming reaction is a method of reforming while balancing the reaction heat by advancing the steam reforming reaction with the heat generated at this time while oxidizing part of the raw material for hydrogen production, Since it has a relatively short start-up time and is easy to control, it has recently attracted attention as a hydrogen production method for fuel cells. Also in this case, the reaction is usually carried out in the presence of a metal catalyst, typically a Group VIII metal such as nickel, cobalt, iron, ruthenium, rhodium, iridium and platinum. The amount of steam introduced into the reaction system is preferably 0.3 to 10, more preferably 0.5 to 5, and still more preferably 1 to 3 as a steam / carbon ratio.

  In autothermal reforming, oxygen is added to the raw material in addition to steam. The oxygen source may be pure oxygen, but in many cases air is used. Usually, oxygen is added to such an extent that it can generate an amount of heat that can balance the endothermic reaction associated with the steam reforming reaction, but the amount of addition is appropriately determined in relation to heat loss and external heating installed as necessary. The amount is preferably from 0.05 to 1, more preferably from 0.1 to 0.75, even more preferably as the ratio of the number of moles of oxygen molecules to the number of moles of carbon atoms contained in the raw material for hydrogen production (oxygen / carbon ratio). Is set to 0.2 to 0.6. The reaction temperature of the autothermal reforming reaction is set in the range of 450 ° C. to 900 ° C., preferably 500 ° C. to 850 ° C., more preferably 550 ° C. to 800 ° C., as in the case of the steam reforming reaction. When the raw material for hydrogen production is liquid, the space velocity (LHSV) at this time is preferably selected in the range of 0.1 to 30, more preferably 0.5 to 20, and still more preferably 1 to 10.

  The partial oxidation reaction is a method in which a reforming reaction is advanced by oxidizing a raw material for hydrogen production, and it has attracted attention as a hydrogen production method because it has a relatively short start-up time and can be designed compactly. The catalyst may or may not be used, but when the catalyst is used, a metal catalyst or a perovskite, typically a Group VIII metal such as nickel, cobalt, iron, ruthenium, rhodium, iridium, platinum, etc. The reaction is carried out in the presence of a spinel oxide catalyst. Steam can be introduced to suppress the generation of soot in the reaction system, and the amount thereof is preferably 0.1 to 5, more preferably 0.1 to 3, more preferably 1 to 1, as a steam / carbon ratio. 2.

  In partial oxidation reforming, oxygen is added to the raw material. The oxygen source may be pure oxygen, but in many cases air is used. In order to secure a temperature for proceeding the reaction, the amount added is appropriately determined in terms of heat loss and the like. The amount is preferably 0.1 to 3, more preferably 0.2 to 0.7 as the ratio of the number of moles of oxygen molecules to the number of moles of carbon atoms contained in the raw material for hydrogen production (oxygen / carbon ratio). . The reaction temperature of the partial oxidation reaction can be in the range of 1,000 to 1,300 ° C. when a catalyst is not used, and when a catalyst is used, the reaction temperature is 450 as in the case of the steam reforming reaction. It can be set in the range of from 550C to 900C, preferably from 500C to 850C, and more preferably from 550C to 800C. When the raw material for hydrogen production is liquid, the space velocity (LHSV) at this time is preferably selected in the range of 0.1-30.

  In the present invention, a known reformer capable of performing the above reforming reaction can be used as the reformer.

[Raw materials for hydrogen production]
As a raw material for hydrogen production, any substance that can obtain a reformed gas containing hydrogen by the above reforming reaction can be used. For example, compounds having carbon and hydrogen in the molecule such as hydrocarbons, alcohols and ethers can be used. Preferable examples that can be obtained inexpensively for industrial use or consumer use include methanol, ethanol, dimethyl ether, city gas, LPG (liquefied petroleum gas), gasoline, kerosene and the like. Of these, kerosene is preferable because it is easily available for industrial use and consumer use, and is easy to handle.

[Shift reactor]
The gas generated in the reformer contains, for example, carbon monoxide, carbon dioxide, methane, and steam in addition to hydrogen. Further, nitrogen is also contained when air is used as an oxygen source in autothermal reforming or partial oxidation reforming. Among these, the shift reactor performs a shift reaction in which carbon monoxide is reacted with water and converted into hydrogen and carbon dioxide. Usually, the reaction proceeds in the presence of a catalyst, and a catalyst containing a noble metal such as a mixed oxide of Fe—Cr, a mixed oxide of Zn—Cu, platinum, ruthenium, and iridium is used. Mol%) is preferably reduced to 2% or less, more preferably 1% or less, and even more preferably 0.5% or less. The shift reaction can also be carried out in two stages, in which case a high temperature shift reactor and a low temperature shift reactor are used.

  Since the shift reaction is an exothermic reaction, operating conditions at a low temperature are preferable in terms of equilibrium, but it is actually necessary to maintain a certain temperature depending on the temperature at which the activity of the catalyst used is expressed. Specifically, when the shift is performed in one stage, it is usually in the range of 100 to 450 ° C, preferably 120 to 400 ° C, more preferably 150 to 350 ° C. If the temperature is lower than 100 ° C, the activity is difficult to be expressed due to the CO adsorption of the catalyst itself, and it is disadvantageous in that the CO conversion tends not to be performed well. In addition, the CO concentration becomes high, and this case is disadvantageous in that there is a tendency that the CO conversion cannot be performed well.

[Selective oxidation reactor]
In order to further reduce the carbon monoxide concentration in the shift reactor outlet gas, the shift reactor outlet gas can be treated with a selective oxidation reaction. In this step, a catalyst containing iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, silver, gold, etc. is used, preferably 0.5 to the number of moles of carbon monoxide remaining. The carbon monoxide concentration is preferably increased by selectively converting carbon monoxide to carbon dioxide by adding 10 moles, more preferably 0.7-5 moles, and even more preferably 1-3 moles of oxygen. Is reduced to 10 ppm (on a molar basis of the dry base) or less. In this case, the carbon monoxide concentration can be reduced by reacting with the coexisting hydrogen simultaneously with the oxidation of carbon monoxide to generate methane. The selective oxidation reaction can also be performed in two stages.

Although the selective oxidation reaction varies depending on the catalyst used and the structure of the container, it is usually carried out in the range of 50 to 250 ° C, preferably 60 to 220 ° C, more preferably 80 to 200 ° C. If it is lower than 50 ° C., it is disadvantageous in that the activity of the catalyst does not appear well and CO tends to be not reduced well, and if it exceeds 250 ° C., in the case of CO selective oxidation. This is disadvantageous in that it tends to lead to excessive consumption of hydrogen due to a decrease in combustion selectivity, leading to an increase in catalyst bed temperature and a reduction in the reforming process efficiency of the entire hydrogen production equipment. This is disadvantageous in that not only CO but also CO ₂ co-existing in a large amount may occur, resulting in a thermal runaway state.

[Desulfurizer]
Since sulfur in the raw material for hydrogen production has an effect of inactivating the reforming catalyst, it is desirably as low as possible, preferably 0.1 mass ppm or less, more preferably 50 mass ppb or less. For this reason, if necessary, the raw material for hydrogen production can be desulfurized in advance. There is no restriction | limiting in particular in the sulfur concentration in the raw material used for a desulfurization process, If it can convert into said sulfur concentration in a desulfurization process, it can be used.

  There is no particular limitation on the desulfurization method, but an example is a method in which hydrogen sulfide produced by hydrodesulfurization in the presence of a suitable catalyst and hydrogen is absorbed by zinc oxide or the like. Examples of the catalyst that can be used in this case include catalysts containing nickel-molybdenum, cobalt-molybdenum, and the like as components. On the other hand, if necessary in the presence of an appropriate sorbent, a method of sorbing a sulfur component in the presence of hydrogen can also be employed. Examples of sorbents that can be used in this case include sorbents mainly composed of copper-zinc as shown in Japanese Patent No. 2654515, Japanese Patent No. 2688749, and so on. Examples thereof include an adhesive.

(Catalyst shape)
In any of a desulfurization catalyst (including a sorbent), a reforming catalyst, a shift catalyst, and a selective oxidation catalyst, the shape of the catalyst is appropriately selected. Typically, it is granular, but in some cases, it may have a honeycomb shape.

[Composition of hydrogen-containing gas]
When the steam reforming reaction is used in the reformer, the composition of the gas that has passed through the reformer (mol% in dry base) is typically, for example, 63 to 73% hydrogen, 0.1 to 5% methane, 5 to 5 carbon dioxide. 20%, carbon monoxide 5-20%. On the other hand, the composition when using the autothermal reforming reaction (mol% in dry base) is usually 23 to 37% hydrogen, 0.1 to 5% methane, 5 to 25% carbon dioxide, 5 carbon monoxide, for example. -25%, nitrogen 30-60%. The composition in the case of using a partial oxidation reaction (mol% on a dry basis) is usually 15 to 35% hydrogen, 0.1 to 5% methane, 10 to 30% carbon monoxide, 10 to 40% carbon dioxide, Nitrogen is 30-60%.

  When the steam reforming reaction is used in the reformer, the composition of the gas that has passed through the reformer and the shift reactor (mol% or mol ppm in dry base) is usually, for example, 65 to 75% hydrogen, 0.1 to methane 0.1 5%, carbon dioxide 20-30%, carbon monoxide 1000 ppm-10000 ppm. On the other hand, the composition when using the autothermal reforming reaction (mol% or mol ppm of dry base) is usually 25 to 40% hydrogen, 0.1 to 5% methane, 20 to 40% carbon dioxide, one Carbon oxide is 1000 ppm to 10000 ppm and nitrogen is 30 to 54%. The composition when using the partial oxidation reforming reaction (mol% in dry base) is usually 20 to 40% hydrogen, 0.1 to 5% methane, 1000 ppm to 10000 ppm carbon monoxide, 20 to 45% carbon dioxide, for example. Nitrogen 30-55%.

  The composition of the gas that has passed through the reformer, shift reactor, and selective oxidation reactor (mol% of the dry base) is usually, for example, 65 to 75% hydrogen, 0. 1 to 5%, carbon dioxide 20 to 30%, nitrogen 1 to 10%. On the other hand, the composition (dry base mol%) when using the autothermal reforming reaction is usually, for example, 25 to 40% hydrogen, 0.1 to 5% methane, 20 to 40% carbon dioxide, and 30 to 54 nitrogen. %. The composition when the partial oxidation reforming reaction is used (mol% in dry base) is usually 20 to 40% hydrogen, 0.1 to 5% methane, 20 to 45% carbon dioxide, and 30 to 55% nitrogen. is there.

〔Fuel cell〕
As the fuel cell, a fuel cell of a type in which hydrogen is a reactant of the electrode reaction in the fuel electrode can be appropriately employed. For example, a fuel cell of a solid polymer type, a phosphoric acid type, a molten carbonate type, or a solid oxide type can be employed. Hereinafter, the configuration of the polymer electrolyte fuel cell will be described.

  The fuel cell electrode is composed of an anode (fuel electrode) and a cathode (air electrode) and a solid polymer electrolyte sandwiched between them. The hydrogen-containing gas produced by the hydrogen production apparatus is on the anode side, and the air is on the cathode side. These oxygen-containing gases are introduced after appropriate humidification treatment if necessary.

  At this time, a reaction in which hydrogen gas becomes protons and emits electrons proceeds at the anode, and a reaction in which oxygen gas obtains electrons and protons to become water proceeds at the cathode. In order to promote these reactions, platinum black and Pt catalyst or Pt-Ru alloy catalyst supported on activated carbon are used for the anode, and platinum black and Pt catalyst supported on activated carbon are used for the cathode. Usually, both the anode and cathode catalysts are formed into a porous catalyst layer together with Teflon, a low molecular weight polymer electrolyte membrane material, activated carbon or the like as necessary.

  As solid polymer electrolytes, Nafion (Nafion, manufactured by DuPont), Gore (Gore, manufactured by Gore), Flemion (Flemion, manufactured by Asahi Glass), Aciplex (Aciplex, manufactured by Asahi Kasei), etc. A molecular electrolyte membrane is usually used, and the porous catalyst layer is laminated on both sides thereof to form an MEA (Membrane Electrode Assembly). Further, the fuel cell is assembled by sandwiching the MEA with a separator having a gas supply function, a current collecting function, particularly an important drainage function in the cathode, and the like made of a metal material, graphite, carbon composite and the like. The electric load is electrically connected to the anode and the cathode.

[Hydrogen-containing gas storage means]
The reformed gas produced in the reformer contains hydrogen, the gas obtained by treating the reformed gas in the shift reactor, and the gas treated in the selective oxidation reactor also contains hydrogen. In addition, when the gas produced by the hydrogen production device is supplied to the anode chamber of the fuel cell and supplied to power generation, hydrogen is consumed but the hydrogen utilization rate does not reach 100% and is discharged from the anode chamber. Hydrogen is also contained in the anode off gas. The hydrogen-containing gas is a gas that substantially contains hydrogen, and the gas downstream of the reformer of the hydrogen production apparatus and the anode off gas are the hydrogen-containing gas. In the present invention, a storage means for storing such a hydrogen-containing gas is used.

  The storage means can be used as long as it has a structure and material capable of storing and releasing gas, particularly hydrogen-containing gas. However, as will be described in detail later with reference to FIG. Those having a liquid-sealed structure are preferred. The liquid seal structure is a structure that seals between the hydrogen-containing gas and the atmosphere with a liquid. For example, two sealable containers are provided, the first container is connected to a line through which hydrogen-containing gas flows during hydrogen production, and the hydrogen-containing gas can flow in, and the second container has an openable atmosphere open line. The containers are open to the atmosphere, and these containers communicate with each other at the bottom, and liquids such as water are accommodated in these containers. As the liquid, for example, when the raw material for hydrogen production is liquid, the raw material for hydrogen production can be used. However, for example, hydrocarbons having 2 or more carbon atoms may deteriorate the shift catalyst. Water is preferably used in order to prevent the raw material vapor from entering the line to which the storage means is connected.

  By using the storage means having such a structure, it is easy to balance the inside of the line and the atmospheric pressure when stopping. In addition, a gas level can be easily controlled by providing a liquid level gauge in at least one of these containers and controlling the opening and closing of the open air line based on the water level measured by the liquid level system.

  Only one storage means may be used, or a plurality of storage means may be provided in parallel at the same location in the process flow. A plurality of storage means can be provided separately at different points in the process flow.

  The capacity of the storage means is such that when the hydrogen production device is stopped and when it is cooled from the operating temperature to room temperature, the gas filling portion of the raw material and product gas in the hydrogen production device is larger than required by volume shrinkage due to cooling. If you have.

  Specifically, it is preferable to have the same volume as the space volume in the hydrogen production apparatus where gas can flow from the storage means when stopped. That is, for example, the volume of the desulfurizer, reformer, shift reactor, selective oxidation reactor and the volume of the space connecting them. Or the volume which remove | excluded the volume which the solid part of a catalyst occupies may be sufficient from the volume of the above-mentioned hydrogen production apparatus. Furthermore, the volume obtained by removing the volume occupied by the solid content of the catalyst from the volume of the hydrogen production apparatus may be a volume that shrinks when each reactor is cooled from the operating temperature to room temperature.

  Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. In the valve indications in the figure, the white ones indicate open valves, and the ones with black ones indicate closed valves. The black arrows indicate the forced flow direction of the fluid. The hatched arrow means the direction in which air naturally flows from the atmosphere as the temperature decreases. The white arrow indicates the direction in which the hydrogen-containing gas released from the storage means flows.

[Hydrogen production equipment]
[Example 1]
FIG. 1 is a flowchart showing an outline of one embodiment of the hydrogen production apparatus of the present invention. As shown in FIG. 1 (a), during operation of the hydrogen production apparatus, the raw material supply valve 101 is opened, and the raw material for hydrogen production is supplied to the reformer 11. At this time, the raw material for hydrogen production can be boosted by a boosting means such as a pump or a blower as necessary. In addition, other substances necessary for hydrogen production, such as reactants for reforming reactions other than raw materials for hydrogen production, can be appropriately supplied to the hydrogen production apparatus. For example, when steam is required for the reforming reaction, steam or water can be supplied to the hydrogen production device. When oxygen is required for the reforming reaction, an oxygen-containing gas such as air is supplied to the hydrogen production device. can do. Further, an oxygen-containing gas such as air for oxidation reaction can be supplied to the selective oxidation reactor.

  In the reformer 11, a reformed gas is produced by a reforming reaction. In some cases, the reformed gas can be used as the product gas as it is. When the reformer is an external heat type reformer, that is, a type in which a reaction tube containing a reforming catalyst is heated from the outside by a combustion means such as a burner to supply heat necessary for the reforming reaction In the case of this reformer, the combustion fuel and air can be appropriately supplied.

  FIG. 1 shows a hydrogen production apparatus for producing a hydrogen-containing gas suitable for a polymer electrolyte fuel cell. A shift reactor 12 and a selective oxidation reactor 13 are arranged downstream of the reformer in the flow direction of the hydrogen-containing gas. Provided in this order from the upstream side, the carbon monoxide concentration in the reformed gas is reduced to become a product gas. If necessary, the product gas can be made after condensing water in the gas.

  The valve 103 is opened, and the hydrogen-containing gas at the outlet of the selective oxidation reactor is supplied as product gas from the product gas outlet 14 to facilities connected downstream such as hydrogen utilization facilities and hydrogen storage facilities. On the other hand, the hydrogen-containing gas is branched upstream of the valve 103 and stored in the storage means 1.

  Here, a branch line is connected to a line through which a hydrogen-containing gas flows during hydrogen production, and the hydrogen-containing gas is led to the storage means. However, in the present invention, the storage means having two openings is not directly connected to the hydrogen. It can also be connected in a line through which hydrogen-containing gas flows during production.

  As shown in FIG. 1B, when stopping, the supply of the raw material for hydrogen production is stopped, the raw material supply valve 101 is closed, and the raw material supply line is shut off. When steam, water, air, or the like is supplied as a reactant for the reforming reaction, or when steam or water is supplied to prevent carbon deposition, these supply lines are also cut off as appropriate. Further, when supplying fuel or air for combustion to the reformer, these supply lines are also cut off as appropriate. Furthermore, the supply line of oxygen-containing gas such as air supplied to the selective oxidation reactor is also cut off as appropriate.

  Further, by closing the valve 103 in addition to the valve 101 and the like, the line through which the hydrogen-containing gas flows from the reformer to the product gas outlet is blocked downstream of the branch point to the storage means. As a result, the line including the reformer and the storage means becomes a single closed space. And hydrogen-containing gas is discharge | released from a storage means.

  As described above, a valve can be used as means for creating a closed space.

  As described above, by stopping the supply of the supply substance to the hydrogen production apparatus and shutting off the supply line, and closing the line including the reformer and the storage means, and releasing the hydrogen-containing gas from the storage means When the temperature of the hydrogen production apparatus is lowered, it is possible to prevent this line from becoming negative pressure due to the hydrogen-containing gas, and to prevent oxidative deterioration of the catalyst.

[Example 2]
FIG. 2 shows an embodiment in which the hydrogen production apparatus of the form shown in FIG. 1 has a configuration using storage means having a water seal structure as storage means. This storage means has two tanks, a hydrogen-containing gas reservoir tank 1a and a buffer tank 1b. A water level gauge 1c is provided in the hydrogen-containing gas reservoir tank. At the top of the buffer tank, an open air line that can be opened and closed by a valve 1d is connected. The two tanks communicate with each other at the bottom and contain water 1e.

  As shown in FIG. 2 (a-1), the hydrogen-containing gas downstream of the selective oxidation reactor flows into the reservoir tank 1a during hydrogen production. With the inflow of the hydrogen-containing gas, the water level of the reservoir tank is lowered and the water level of the buffer tank is raised. As shown in FIG. 2 (a-2), when it is determined by the water level gauge 1c that the water level of the reservoir tank has reached a predetermined position, the valve 1d is closed and the air release line is shut off. Thereby, the inflow of the hydrogen-containing gas can be stopped. The hydrogen-containing gas is discharged as a product without substantially flowing into the storage means. The predetermined position can be calculated from the amount of gas to be stored and the dimensions of the tank.

  At the time of stoppage, the line including the reformer, the shift reactor, the selective oxidation reactor and the storage means is closed by the valves 101 and 103, and the valve 1d is opened. Since the water level of the buffer tank is higher than the water level of the reservoir tank, the hydrogen-containing gas stored in the reservoir tank flows into the selective oxidation reactor or the like due to this head difference. This prevents negative pressure in the line and protects the catalyst.

  The location where the storage means or the branching point branching to the storage means is installed can be appropriately selected from the location where the hydrogen-containing gas flows during hydrogen production, that is, the downstream of the reformer. For example, when the hydrogen production apparatus includes a shift reactor and a selective oxidation reactor in addition to the reformer, it may be downstream of the selective oxidation reactor as shown in FIG. Or between the reformer and the shift reactor.

  However, from the viewpoint of suppressing heat loss from the storage means, and from the viewpoint of suppressing vaporization when liquid is stored in the storage means, a branch that branches to the storage means or the storage means at a location where a gas having a low temperature flows. It is preferable to provide a point. From this point of view, in the embodiment of FIGS. 1 and 2, the downstream of the selective oxidation reactor is preferable as the installation location.

  In addition, the line including the reformer and the storage means is closed at the time of stoppage to create a closed space (a space closed by the valve 101 and the valve 103 in FIGS. 1B and 2B). The reactor having the catalyst to be contained is included in this closed space. Since the shift reaction catalyst is often susceptible to oxidative degradation, the shift reactor is preferably included in this closed space when a shift reactor is present. The selective oxidation reaction catalyst often withstands some oxidation, so when the atmosphere does not flow into the selective oxidation reactor at the time of shutdown and it is not necessary to have negative pressure (such as when there is a separate air release means) The selective oxidation reactor may not be included in this closed space. When this closed space includes a shift reactor and does not include a selective oxidation reactor, a branch point for branching to the storage means or the storage means is provided between the shift reactor and the selective oxidation reactor from the viewpoint of the gas temperature described above. It is preferable to provide the valve 103 downstream and upstream of the selective oxidation reactor.

  In the present invention, the above operations can be performed automatically by using a control device such as a control computer or a sequencer and using a valve as an automatic valve.

  In the present invention, the above-described operations, that is, the supply stop of the supply to the hydrogen production apparatus, the line shut off, and the release of the hydrogen-containing gas from the storage means can be performed simultaneously. Therefore, the stop operation is simple. In addition, since it is not necessary to operate a blower or the like for purging after the stop, no necessary power is required for this purpose, and there is an energy saving effect. Even when the valve operation around the storage means as shown in FIG. 2 is performed after the stop, such an operation is a simple operation in a very limited part and requires very little energy.

[Fuel cell system]
Example 3
FIG. 3 is a flowchart showing an outline of one embodiment of the fuel cell system of the present invention. This configuration is based on a configuration in which the hydrogen production apparatus 100 and the fuel cell 2 shown in FIG. 1 are combined, and is suitable for a polymer electrolyte fuel cell.

  During operation of the fuel cell system, the valves 101 and 103 are opened as shown in FIG. The hydrogen-containing gas produced by the hydrogen production apparatus 100 is supplied to the anode chamber 2a of the fuel cell 2 and used for power generation. Since the anode off-gas discharged from the anode chamber contains a combustible substance such as unused hydrogen, it is burned by a burner 11b provided in the reformer 11 for supplying heat necessary for the reforming reaction. The combustion gas of the burner is appropriately recovered and then discharged to the atmosphere. A hydrogen-containing gas downstream of the selective oxidation reactor 13 is supplied to the storage means 1.

  In FIG. 1 and the like related to the hydrogen production apparatus, heating means such as a burner for supplying heat necessary for the reforming reaction provided as necessary is not shown, but FIG. 3 related to the fuel cell system is not shown. In FIG. 6, a burner is shown, and a region where a reforming reaction occurs is distinguished as a reforming reaction tube 11a filled with a reforming catalyst. In FIG. 1 and the like, the reformer 11 means a region where a reforming reaction occurs.

  On the other hand, air is supplied from the atmosphere to the cathode chamber 2c of the fuel cell by the air boosting means 4 such as a blower or a compressor, is used for power generation, and is then discharged to the atmosphere. Air used for combustion in the burner 11b is also supplied from the pressurizing means 4.

  As shown in FIG. 3B, when the fuel cell system is stopped, the supply of the raw material for hydrogen production is stopped, the valve 101 is closed, and the raw material supply line is shut off. If there is something that has been supplied to the hydrogen production apparatus in addition to the raw material for hydrogen production, the supply is stopped and the supply line is shut off by a valve or the like. Moreover, supply other than the thing supplied to the hydrogen production apparatus 100, such as stopping the air pressurization means 4, can be stopped.

  By closing the valve 103 in addition to the valve 101 and the like, the line including the reformer (reforming reaction tube 11a) and the storage means 1 between the valves 101 and 103 is closed.

  As in the case of the hydrogen production apparatus, the hydrogen-containing gas is released from the storage means into this closed space, thereby preventing negative pressure and oxidative deterioration of the catalyst. Moreover, when the influence of the negative pressure can be ignored, the release of the hydrogen-containing gas may be stopped.

  On the other hand, air can naturally flow into the fuel cell anode chamber 2a from the atmosphere via the burner 11b from the combustion gas line of the reformer communicating with the atmosphere. A catalyst may also be used for the anode, but for example, in a polymer electrolyte fuel cell, the fuel cell itself is at a relatively low temperature, and the influence of slight oxygen contamination is often negligible.

  In addition, air can naturally flow into the cathode chamber 2c from the cathode chamber outlet line, and air can also flow naturally through the air booster 4 or through the burner 11b. Since the cathode system originally flows air, it is not necessary to flow a hydrogen-containing gas.

  The anode off-gas line is a line through which a combustible gas containing unused hydrogen discharged from the anode chamber flows. In the form of FIG. 3, since the anode off gas is burned in the burner 11b, the line from the outlet of the anode chamber 2a to the burner 11b is the anode off gas line.

Example 4
FIG. 4 shows another embodiment of the fuel cell system of the present invention. In this embodiment, the storage means 1 is connected to the anode off-gas line downstream of the anode chamber 2a, and a valve 103 for creating a closed space is provided downstream of the branch point to the storage means. The storage means stores an anode off gas as a hydrogen-containing gas. By closing the valve 101 and the valve 103 during the stop, a closed space including the reformer (reforming reaction tube 11a), the shift reactor, the selective oxidation reactor, the anode chamber, and the storage means is formed.

  In this embodiment, the hydrogen-containing gas released from the storage means at the stop flows into the anode chamber 2a, the selective oxidation reactor 13, the shift reactor 12, and the reformer (reforming reaction tube 11a). That is, this form is suitable when the hydrogen-containing gas flows into the anode chamber and the anode chamber dislikes the mixing of oxygen.

  In the form shown in FIG. 3 or the form shown in FIG. 4, a storage means having a liquid seal structure as shown in FIG. 2 can be used. In that case, the operation of stopping the release of the hydrogen-containing gas from the storage means is unnecessary, and the atmospheric pressure and the pressure in the closed space are naturally balanced.

  In the present invention, the above-described operations, that is, the supply of fuel to the fuel cell system and the line are shut off, the hydrogen-containing gas is released from the storage means, and the air pressurization means are stopped simultaneously. Therefore, the stop operation is simple. In addition, since it is not necessary to operate the blower for purging after the stop, no power is required for that purpose, and there is an energy saving effect. Conventionally, nitrogen purging has been performed while continuing combustion of a burner or the like provided in the reformer until a certain point after the stop, but according to the present invention, it is necessary to perform combustion by such a burner after the stop. There is no energy saving effect in this respect as well.

  Even when the valve operation around the storage means as shown in FIG. 2 is performed after the stop, such an operation is a simple operation in a very limited part and requires very little energy.

[Other equipment]
In addition to the above devices, known components of a hydrogen production apparatus using a reformer and known components of a fuel cell system can be appropriately provided as necessary. Specific examples include a steam generator for generating steam for humidifying the gas supplied to the fuel cell, a cooling system for cooling various devices such as the fuel cell, a pump for compressing various fluids, and a compressor Pressurizing means such as a blower, flow rate adjusting means such as a valve for adjusting the flow rate of the fluid, or shutting off / switching the flow of the fluid, and a flow path shutting / switching means, heat for heat exchange and heat recovery Exchangers, vaporizers that vaporize liquids, condensers that condense gases, heating / heat-retaining means that externally heat various devices with steam, storage means for various fluids, instrumentation air and electrical systems, control signal systems , Control devices, electrical systems for output and power.

  The hydrogen production apparatus of the present invention can be used for producing a hydrogen-containing gas as fuel for a fuel cell, and can be used in a hydrogen station for supplying a hydrogen-containing gas to an automobile.

  The fuel cell system of the present invention can be used for a power generator for a moving body such as an automobile, a fixed power generation system, a cogeneration system, and the like.

It is a flowchart showing the outline of one form of the hydrogen production apparatus of this invention. It is a flowchart showing the outline of another form of the hydrogen production apparatus of this invention. It is a flowchart showing the outline of one form of the fuel cell system of this invention. It is a flowchart showing the outline of another form of the fuel cell system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Storage means 1a Hydrogen-containing gas reservoir tank 1b Buffer tank 1c Water level gauge 1d Valve 2 Fuel cell 2a Anode chamber 2c Cathode chamber 4 Air boosting means 11 Reformer 11a Reforming reaction tube 11b Burner 12 Shift reactor 13 Selective oxidation reactor 14 Product gas outlet 100 Hydrogen production equipment 101, 103 Valve

Claims (8)

In a method for operating a hydrogen production apparatus having at least a reformer for producing a gas containing hydrogen from a raw material for hydrogen production using a reforming reaction,
During hydrogen production, the hydrogen-containing gas downstream of the reformer is stored in the storage means,
A method of operating a hydrogen production apparatus, characterized in that, when stopped, a line including the reformer and the storage means is closed, and the hydrogen-containing gas stored in the storage means is released.   The method according to claim 1, wherein the storage means has a liquid sealing structure that seals between the hydrogen-containing gas and the atmosphere with a liquid. In a hydrogen production apparatus having at least a reformer for producing a gas containing hydrogen from a raw material for hydrogen production using a reforming reaction,
Having storage means for storing the hydrogen-containing gas downstream of the reformer;
An apparatus for producing hydrogen, comprising: a reformer and a means for closing a line including the storage means.   The hydrogen production apparatus according to claim 3, wherein the storage means has a liquid sealing structure that seals between the hydrogen-containing gas and the atmosphere with a liquid. A hydrogen production apparatus having at least a reformer for producing a gas containing hydrogen from a raw material for hydrogen production using a reforming reaction, and a fuel that generates electricity using a hydrogen-containing gas obtained from the hydrogen production apparatus In a method for operating a fuel cell system having a battery,
Storing hydrogen-containing gas downstream of the reformer in the storage means during hydrogen production by the hydrogen production apparatus;
When stopping the fuel cell system, the line including the reformer and the storage means is closed, and the hydrogen-containing gas stored in the storage means is discharged. .   The method according to claim 5, wherein the storage means has a liquid seal structure that seals between the hydrogen-containing gas and the atmosphere with a liquid. A hydrogen production apparatus having at least a reformer for producing a gas containing hydrogen from a raw material for hydrogen production using a reforming reaction, and a fuel that generates electricity using a hydrogen-containing gas obtained from the hydrogen production apparatus In a fuel cell system having a battery,
Having storage means for storing the hydrogen-containing gas downstream of the reformer;
A fuel cell system comprising means for closing a line including a reformer and the storage means into a closed space.   8. The fuel cell system according to claim 7, wherein the storage means has a liquid sealing structure that seals between the hydrogen-containing gas and the atmosphere with a liquid.

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