JP2002334714A - Hydrogen production system incorporating a fuel cell - Google Patents

Abstract

(57) Abstract: CO inevitably contained in hydrogen obtained by a hydrogen production system using off-gas or excess heat of a fuel cell
_2. Eliminate various obstacles. The A solid oxide fuel cell of the off-gas to a system for producing hydrogen through a CO shift converter, to remove the CO ₂ through a modified gas in the CO transformer to CO ₂ absorbent layer And a high-purity hydrogen production system characterized in that the high-purity hydrogen obtained by the high-purity hydrogen production system is used as a fuel for a polymer electrolyte fuel cell. Fuel cell system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen production system utilizing off-gas and excess heat of a fuel cell, and a fuel cell system utilizing hydrogen obtained by the hydrogen production system.

[0002]

2. Description of the Related Art A hydrogen production system utilizing off-gas and excess heat of a fuel cell is being developed. For example, when a solid oxide fuel cell (SOFC) is used, its operating temperature is as high as about 1000 ° C.
It is conceivable that the off-gas after the internal reforming is directly performed in C and used for power generation, or the case where the generated heat is separately used as heat for steam reforming of methane. FIG. 1 shows an example in which off-gas is used after performing internal reforming directly in an SOFC and supplying it to power generation. FIG. 2 shows heat generated during operation (ie, surplus heat) separately from heat required for steam reforming of methane. It is a figure showing the example used as.

[0003] On the other hand, in the steam reforming method, methane and other hydrocarbon gases (including a mixed gas of two or more hydrocarbons such as natural gas, city gas, or LP gas) and alcohols such as methanol are reformed with steam. And reformed into hydrogen-rich reformed gas. The reformed gas thus obtained is also used as fuel. A reformer is used to perform the steam reforming method, and a hydrogen-rich reformed gas is generated from hydrocarbon gas or alcohols by a catalytic reaction using a reforming catalyst.

FIG. 3 schematically shows a steam reformer.
In general, it is composed of a combustion section in which a burner or a combustion catalyst is arranged and a reforming section in which a reforming catalyst is arranged. The reforming section is filled with a Ni-based, Ru-based, or other reforming catalyst and disposed therein. If the raw material gas contains a sulfur compound, the reforming catalyst is poisoned and the performance is deteriorated.Therefore, the sulfur compound is removed in advance and mixed with steam from a separately provided steam generator. Into the reforming section of the reformer.

[0005] Since the catalytic reaction (= reforming reaction) occurring in the reforming section involves a large endotherm, it is necessary to supply heat from the outside in order for the reaction to proceed, and a temperature of about 600 ° C. or higher is required. . Therefore, the fuel gas is burned by air in the combustion section, and the generated combustion heat (ΔH) is supplied to the reforming section. In the example of FIG. 2, instead of heating by the combustion unit, SOF
The generated heat (surplus heat) during the operation of C is used.

Reforming when the source gas is, for example, methane
The reaction is "CH_Four+ 2H_TwoO → CO_Two+ 4H_Two".
Unreacted methane and unreacted water vapor are contained in the reformed gas generated.
Gas, carbon dioxide (CO_Two), And carbon monoxide (CO)
8 to 15% by volume (% by volume, same hereafter)
I have. Therefore, the reformed gas converts this by-product CO into carbon dioxide gas.
It is subjected to a CO converter to remove it in an alternate manner. CO change
Catalysts such as copper-zinc and platinum catalysts are used in the generator
However, in order for the catalyst to function,
Temperature is required. The reaction in the CO converter is "CO + H
_TwoO → CO_Two+ H _TwoRequired for this shift reaction.
Unreacted residual steam is used in the reformer as steam.
You.

[0007] The reformed gas emitted from the CO converter is composed of hydrogen and carbon dioxide gas except for unreacted methane and excess steam. Of these, hydrogen is the target component, but C
Also in the reformed gas obtained through the O shift converter, CO is not completely removed, but contains a trace amount of CO. C in fuel hydrogen supplied to polymer electrolyte fuel cell (PEFC)
The O content is limited to about 100 ppm (capacity ppm, the same applies hereinafter). If the O content is exceeded, the battery performance deteriorates remarkably. Therefore, it is necessary to remove as much as possible before introducing into the PEFC.

For this reason, the reformed gas is converted into C by the CO converter.
After reducing the O concentration to about 1% or less, it is subjected to a CO selective oxidizer. Here, an oxidizing gas such as air is added, and CO is reduced to about 100 ppm or less, preferably 50 pp by an oxidation reaction of CO (CO + 1 / 2O ₂ = CO ₂ ).
m, more preferably 10 ppm or less. Operating temperature of CO selective oxidizer is 100 ~ 15
It is about 0 ° C. The hydrogen thus purified is supplied to the fuel electrode of the PEFC.

FIG. 4 shows an example in which hydrogen obtained by using off-gas after performing internal reforming directly in an SOFC and supplying it to power generation as shown in FIG. 1 is used as a PEFC fuel. FIG.
FIG. 2 shows an example in which hydrogen obtained by using generated heat (excess heat) during SOFC operation as heat necessary for steam reforming of methane separately as shown in FIG. 2 is used as fuel for PEFC.

[0010] PEFC or molten carbonate fuel cell (MCF
In the case of using the off-gas or surplus heat of C), since the operating temperature of the battery is too low to reform hydrocarbon gas such as methane, it is difficult to directly use internal reforming or surplus heat. Do not go. However, for example, in the case of a PEFC, the reformer and the PEFC are combined to burn off gas of the PEFC, and the combustion heat is used as a heat source of the reformer. FIG. 6 is a diagram showing this example.

Incidentally, when the hydrocarbon is methane,
Hydrogen and CO in the reformed gas (reformed gas) have a composition of 3: 1 (CH ₄ + H ₂ O → 3H ₂ + CO), but the hydrogen used for power generation in the fuel cell is converted to water (steam). , CO is CO
Turns into ₂ . Therefore, a large amount of CO ₂ is contained in the off-gas from the fuel cell, and as a result, hydrogen produced using the off-gas contains a large amount of CO ₂ .

In any of the above hydrogen production systems, hydrogen produced using off-gas is
Since a large amount of CO ₂ is contained, this hydrogen is
When the fuel is used as a fuel for fuel, the electromotive force in the battery is lower than when high-purity hydrogen is used as the fuel. In addition, a reverse shift reaction “CO ₂ + H ₂
There is also a risk that CO is generated by “→ CO + H ₂ O” and the fuel electrode is deteriorated. Furthermore, SOFC or PE
In a system that uses combustion heat by burning off-gas of FC, there is also a risk of unstable combustion.

[0013]

SUMMARY OF THE INVENTION The present invention relates to a conventional fuel cell such as a solid oxide fuel cell (SOFC), a polymer electrolyte fuel cell (PEFC), or a molten carbonate fuel cell (MCFC). occurs in systems for producing hydrogen by using, has been made to solve the above problems, CO metamorphic gas or a fuel cell off-gas in the CO transformer ₂ adsorbent or CO ₂
A system for producing high-efficiency and high-purity hydrogen by removing or removing CO ₂ as much as possible using an absorbent, and a fuel cell system using the high-purity hydrogen produced by the hydrogen production system as a fuel The purpose is to provide.

[0014]

The present invention provides (1) a system for producing hydrogen by passing an off-gas of a solid oxide fuel cell through a CO converter, wherein the gas converted by the CO converter is converted into CO _2. To provide a high-purity hydrogen production system characterized by removing CO ₂ through the absorbent layer,
(2) A fuel cell system characterized in that high-purity hydrogen obtained by the high-purity hydrogen production system is used as a fuel for a polymer electrolyte fuel cell.

According to the present invention, (3) a hydrocarbon is reformed by steam reforming using excess heat of a solid oxide fuel cell,
A system for producing hydrogen through a CO converter,
The gas converted in the CO converter is passed through the CO ₂ absorbent layer to remove C.
A high-purity hydrogen production system characterized by removing O ₂ is provided. (4) High-purity hydrogen obtained by the high-purity hydrogen production system is used as a fuel for a polymer electrolyte fuel cell. There is provided a fuel cell system characterized in that it is used.

The present invention provides (5) a system for reforming hydrocarbons by steam reforming using combustion heat generated by burning off-gas of a polymer electrolyte fuel cell, and producing hydrogen through a CO converter. Wherein the gas converted by the CO converter is
₍₂ ) To provide a high-purity hydrogen production system characterized in that CO ₂ is removed through an absorbent layer, and (6) high-purity hydrogen obtained by the high-purity hydrogen production system A fuel cell system characterized by being used as a fuel for a molecular fuel cell.

The present invention provides (7) a system in which hydrocarbons are reformed by steam reforming using the combustion heat generated by burning off-gas of a polymer electrolyte fuel cell, and the reformed hydrocarbons are passed through a CO converter to produce hydrogen. a is, after removal of the CO ₂ through the off-gas to CO ₂ absorber layer, with burning, and the modified gas with CO transformer so as to remove the CO ₂ through CO ₂ absorbent layer And (8) using the high-purity hydrogen obtained by the high-purity hydrogen production system as a fuel for a polymer electrolyte fuel cell. A featured fuel cell system is provided.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The present invention (1), in a system for producing hydrogen through the off-gas of the SOFC to the CO shift converter, the CO ₂ through a modified gas in the CO transformer to CO ₂ absorbent layer It is characterized by being removed. The present invention (3)
In a system in which hydrocarbons are reformed by steam reforming using the excess heat of an SOFC and hydrogen is produced through a CO converter, the gas transformed by the CO converter is passed through a CO ₂ absorbent layer. It is characterized by removing CO ₂ .

The present invention (5) relates to a system for reforming hydrocarbons by steam reforming using the combustion heat generated by burning off-gas of PEFC and producing hydrogen through a CO converter. in through modified gas to CO ₂ absorbent layer, and removing the CO _2. The present invention (7) provides a system for producing hydrocarbons by reforming hydrocarbons by steam reforming using combustion heat generated by burning off-gas of a polymer electrolyte fuel cell and passing the reformed hydrocarbons through a CO converter. after removal of CO ₂ through the off-gas to CO ₂ absorber layer, with burning, and removing the CO ₂ through a modified gas in the CO transformer to CO ₂ absorbent layer.

The fuel cell system according to the present invention utilizes the high-purity hydrogen obtained by any of the high-purity hydrogen production systems (1), (3), (5) and (7) as a fuel for PEFC. This is a fuel cell system configured to perform the above. In the present invention (1), (3), (5) and (7), CO
By providing a CO ₂ absorbent layer at the subsequent stage of the converter to remove CO ₂ in the gas, high-purity hydrogen containing no CO ₂ can be obtained. As a result, the resulting high-purity hydrogen was
When used as an FC fuel, the electromotive force of the PEFC is improved, and electrode deterioration due to CO generated by the reverse shift reaction can be prevented. Further, by removing CO ₂ from the offgas of the SOFC or PEFC, the combustion state when the offgas is burned as in the present invention (7) to (8) can be improved.

The CO ₂ absorbent used in the present invention includes:
In the reformed gas from steam reformer or CO converter or S
Any substance that can absorb CO ₂ in off-gas from OFC or PEFC is used. As a phenomenon in which a gas such as CO ₂ is absorbed (absorbed) by a solid or a liquid, in addition to so-called absorption, there are adsorption and sorption accompanied by reaction or dissolution in adsorption. , referred to as absorption, including sorption, during gas by these phenomena CO ₂
The substance that absorbs is referred to as a CO ₂ absorbent or simply an absorbent. The absorbent can be used in any appropriate form, such as filling the container in the form of granules or granules, or supporting it on a honeycomb-shaped heat-resistant base material and arranging it in the container. They shape in this specification and drawings, it is called the finger and the CO ₂ absorbent layer a state filled or placed into the container the CO ₂ absorbent structure.

As a preferred example of the CO ₂ absorbent used in the present invention, lithiated zirconia (Li ₂ ZrO ₃ or Li _2
4 ZrO ₄ ). Li ₂ ZrO ₃ absorbs CO ₂ by the reaction of the following formula (1). This reaction is
It is a reversible reaction. [Depending on pressure (partial pressure) conditions, etc.] For example, at around 700 ° C., the temperature proceeds to the right at low temperatures and to the left at high temperatures. In addition, the reaction rate in this temperature range is sufficiently fast, and CO ₂ is absorbed at about 600 ° C. in a volume ratio of 520 times that of lithiated zirconia. In the present invention, the removal of CO ₂ in the off-gas of such transformer already gas and fuel cells using the absorbent is discharged from the CO transformer through the reformer in such a temperature range it can.

[0023]

[Formula 1]

For example, an off gas of about 600 ° C. in an SOFC is passed through this lithiated zirconia absorbent to absorb CO _2, and after the absorption is saturated (or immediately before the saturation), this time, for example, about 700 ° C. or more to release CO ₂ through the air lithium zirconia. By repeating this operation, C in the off-gas
The O ₂ can be removed and the absorbent regenerated to repeatedly remove CO ₂ in the transformed gas from the CO converter or in the off-gas from the PEFC.

[0025]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited to these Examples. In each embodiment, the CO ₂ absorbent layer is filled with lithiated zirconia (Li ₂ ZrO ₃ ) as an example and used.

<Embodiment 1> In this embodiment, an off-state from an SOFC is used.
Gas is passed through a CO converter to produce hydrogen.
Off-gas converted by the CO converter_TwoAbsorbent layer
Through CO_TwoThis is an example of removing. SOFC off-gas
Unused CO, H_TwoBesides, CO_Two, H _TwoO included
And especially CO_TwoIs the shift in the CO transformer
Reaction (CO + H_TwoO → CO_Two+ H_Two) Further increase
are doing. As shown in FIG. 7, in this example, the CO transformer
To the conduit following_TwoArrange the absorbent layer. CO_TwoAbsorbent layer
As CO_TwoAbsorbents can be in the form of granules or granules
Or supported on a honeycomb heat-resistant structural substrate
It is constructed by a usual method such as filling or placing in a vessel.
Can be This is the same in the following examples.

CO ₂ contained in SOFC off-gas
And CO ₂ increased by shift reaction in CO converter
, High-purity hydrogen can be produced. Since CO ₂ absorbents such as lithiated zirconia each have an appropriate temperature for absorbing CO _2, an appropriate or optimal absorbent is selected as the CO ₂ absorbent depending on the temperature of the off-gas from the CO converter. However, if necessary, a heat exchanger or the like for adjusting the off-gas to the appropriate temperature may be provided. Further, the absorbent eventually becomes a state where CO ₂ is saturated (or nearly saturated). In this case, the absorbent may be regenerated by heating or the like, or may be replaced with a new absorbent.
These points are the same in the following embodiments.

[0028] <Example 2> This embodiment, in a system for producing hydrogen through the off-gas of the SOFC to the CO shift converter, the CO ₂ is removed through the off-gas was modified with CO transformer to CO ₂ absorbent layer High-purity hydrogen obtained by PEFC
This is an example of using as a fuel. The process up to obtaining high-purity hydrogen is the same as in Example 1. As shown in FIG.
The off-gas transformed by the O-transformer is passed through the CO ₂ absorbent layer to remove CO ₂ and supply the PEFC to the PEFC, so that not only can the electromotive force in the PEFC be reduced but also the deterioration of the fuel electrode can be prevented. be able to. Of these, there is degradation of the fuel electrode and contains CO ₂ in off-gas, CO is generated by the reverse shift reaction in the fuel electrode, the fuel electrode by the CO is degraded, as in this example CO ₂ By removing CO ₂ through the absorbent layer, deterioration of the fuel electrode can be prevented.

In this case, in PEFC, C in fuel hydrogen
Since the O concentration is limited to about 100 ppm, depending on the CO concentration in the off-gas derived from the CO converter, the CO is oxidized through a CO selective oxidizer (not shown in FIG. 8) as necessary. Reaction (CO + 1 / 2O ₂ = C
O ₂ ) reduces the CO concentration to about 100 ppm or less, preferably 50 ppm or less, more preferably 10 ppm or less. The operating temperature of the CO selective oxidizer is about 100 to 150 ° C., and the hydrogen thus purified is supplied to the fuel electrode of the PEFC. Since the operating temperature of PEFC is about 80 to 100 ° C, the reformed gas that has passed through the CO selective oxidizer is
Supplied to

<Embodiment 3> In this embodiment, a hydrocarbon is reformed by steam reforming using surplus heat during operation of an SOFC.
In a system for producing hydrogen through a CO converter,
The gas converted in the CO converter is passed through the CO ₂ absorbent layer to remove C.
This is an example of removing O ₂ . Operating temperature of SOFC is 100
Since the temperature is as high as about 0 ° C., the surplus heat is used for steam reforming of hydrocarbons such as methane to generate a reformed gas. As shown in FIG. 9, in addition of H ₂ as the main component in the reformed gas obtained in the reformer CO _2, H ₂ O In addition, C
O is contained, so that CO is passed through a CO
Change in ₂ and H _2.

However, C in the reformed gas passed through the CO converter
O ₂ is further increased by the shift reaction (CO + H ₂ O → CO ₂ + H ₂ ) in the CO shift converter in addition to the CO ₂ generated in the reformer. Therefore, in this example, by the conduit following the CO transformer should place the CO ₂ absorbent layer, to remove the CO ₂ in the reformed gas, it is a possible thereby producing high purity hydrogen .

<Embodiment 4> In this embodiment, a hydrocarbon is reformed by steam reforming using excess heat of an SOFC, and is passed through a CO converter to produce hydrogen. This is an example in which high-purity hydrogen obtained by passing gas through a CO ₂ absorbent layer to remove CO ₂ is used as a fuel for PEFC. The process up to obtaining high-purity hydrogen is the same as in Example 3. As shown in FIG. 10, a reformed gas modified with CO transformer to remove CO ₂ through CO ₂ absorbent layer P
Since it is supplied to the EFC, as in the case of Example 2, PE
It is possible to prevent a decrease in the electromotive force in the FC and to prevent deterioration of the fuel electrode.

<Embodiment 5> In this embodiment, a system for reforming hydrocarbons by steam reforming using the combustion heat of burning off-gas of PEFC and passing it through a CO converter to produce hydrogen is used. This is an example of removing CO ₂ by passing a gas transformed by a transformer through a CO ₂ absorbent layer. FIG. 11 is a view showing this example, in which raw gas such as city gas is desulfurized by a desulfurizer, and hydrogen obtained through a reformer (reforming unit), a CO shift converter, and a CO selective oxidizer is supplied to the PEFC. You. The offgas of PEFC contains unused hydrogen (H ₂ ) in addition to CO ₂ and H ₂ O. Therefore, the off-gas is burned in a combustor, and the heat of combustion is used as a heat source necessary for steam reforming of hydrocarbons. An oxidizing gas such as air is supplied to the combustor,
In FIG. 11, illustration is omitted. In this regard, the same applies to other drawings in which the combustor is arranged.

Since the reformed gas obtained in the reformer contains CO ₂ , H ₂ O, and CO in addition to H ₂ as a main component, CO is passed through a CO converter to convert CO into CO 2. change in ₂ and H _2. However, CO ₂ in the reformed gas passed through the CO converter is
In addition to the CO ₂ generated in the reformer, it is further increased by a shift reaction (CO + H ₂ O → CO ₂ + H ₂ ) in the CO shift converter. Therefore, in this embodiment, by arranging the CO ₂ absorbent layer to the conduit following the CO transformer, to remove the CO ₂ in the reformed gas. Thereby, high-purity hydrogen can be produced.

Embodiment 6 This embodiment is an example in which high-purity hydrogen obtained as in Embodiment 5 is used as a fuel for PEFC. FIG. 12 is a view showing the present example, and the process up to obtaining high-purity hydrogen is the same as in the fifth embodiment. PEF
In C, since the CO concentration in fuel hydrogen is limited to about 100 ppm, depending on the CO concentration in the off-gas derived from the CO converter, the CO oxidation reaction (CO + 1 / 2O) may be performed through a CO selective oxidizer as necessary. ₂ = CO ₂ ) to reduce the CO concentration to about 100 ppm or less, preferably 50 ppm.
ppm or less, more preferably 10 ppm or less. Operating temperature of CO selective oxidizer is 100 ~
The temperature is about 150 ° C, and the hydrogen thus purified is PEF
C is supplied to the fuel electrode. The operating temperature of PEFC is 80 ~
Since the temperature is about 100 ° C., the reformed gas that has passed through the CO selective oxidizer is supplied to the PEFC after being adjusted to an appropriate temperature by a heat exchanger.

FIG. 12 also shows a system from a desulfurizer (for desulfurizing raw material gas such as city gas) to a PEFC through a reforming section (of a reformer), a CO shift converter, and a CO selective oxidizer. However, this is for supplying fuel hydrogen at the time of starting the PEFC. After the start of the PEFC, the hydrogen generated by the reformer utilizing the heat from the combustor (off-gas combustor) is used as fuel hydrogen as described above. When the raw material gas supplied to the reformer contains a sulfur compound like city gas or LP gas, it is supplied to the reformer after desulfurization. Also, without providing such a system, first, the reformer is operated, and the obtained reformed gas is passed through a CO shift converter and a CO ₂ absorbent layer. It may be supplied as. These points are the same as in Example 8 (FIG. 14) described later.

<Embodiment 7> In this embodiment, a system is used in which hydrocarbons such as methane are reformed by steam reforming using combustion heat obtained by burning off-gas of PEFC, and the hydrogen is produced through a CO converter. In the above, while the off-gas is passed through a CO ₂ absorbent layer to remove CO ₂ and burn,
This is an example of removing CO ₂ by passing a gas transformed by a transformer through a CO ₂ absorbent layer. FIG. 13 illustrates this example.

The offgas of the PEFC contains unused hydrogen in addition to CO ₂ and H ₂ O. Therefore offgas is combusted in the combustor, it utilizes the combustion heat as a heat source for the steam reforming of hydrocarbons, the combustion due to CO ₂ in the off gas upon combustion becomes unstable. Therefore, in the present example, the off gas is passed through the CO ₂ absorbent layer to remove CO ₂ and then combusted, whereby the combustion state in the combustor can be improved. Other points are the same as in the case of the fifth to sixth embodiments.

Embodiment 8 This embodiment is an example in which the high-purity hydrogen obtained as in Embodiment 7 is used as a fuel for PEFC. FIG. 14 shows this example. P
EFC off-gas contains unused hydrogen in addition to CO ₂ and H ₂ O, so this off-gas is burned in a combustor and the heat of combustion is used as a heat source necessary for steam reforming of hydrocarbons. I do. However, during combustion, CO
Combustion becomes unstable due to ₂ . Therefore, in this example, by burning the off-gas through the CO ₂ absorbent layer to remove CO ₂ and then burn it, the combustion state in the combustor can be improved. Other points are the same as in the case of the fifth to sixth embodiments.

[0040]

According to the present invention, in a hydrogen production system utilizing off-gas or surplus heat of SOFC or PEFC, C _{2 is} obtained from CO ₂ -containing hydrogen obtained by using a CO ₂ absorbent.
By removing or removing O ₂ as much as possible, high-purity hydrogen can be produced. In using hydrogen obtained by the hydrogen production system as fuel for a fuel cell,
Not only can the battery electromotive force be reduced, but also the fuel electrode can be prevented from deteriorating. Furthermore, SOFC and PEF
In a hydrogen production system utilizing the combustion heat by burning off gas of C, by burning after removing CO ₂ in the off gas, various useful effects such as improvement of the combustion state can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a hydrogen production system using off-gas of an SOFC

FIG. 2 is a diagram showing an example of a hydrogen production system that uses surplus heat of an SOFC for reforming hydrocarbons.

FIG. 3 is a diagram schematically showing a hydrocarbon steam reformer.

FIG. 4 is a diagram showing a system that uses hydrogen produced using off-gas of SOFC as fuel for PEFC.

FIG. 5 is a diagram showing a system in which hydrogen produced by using surplus heat of SOFC for reforming hydrocarbons is used as fuel for PEFC.

FIG. 6 is a diagram showing a system in which hydrogen produced by utilizing the combustion heat of offgas of PEFC for reforming hydrocarbons is used as fuel for PEFC.

FIG. 7 is a diagram showing a first embodiment of the present invention.

FIG. 8 is a diagram showing a second embodiment of the present invention.

FIG. 9 is a diagram showing a third embodiment of the present invention.

FIG. 10 is a diagram showing a fourth embodiment of the present invention.

FIG. 11 shows a fifth embodiment of the present invention.

FIG. 12 is a diagram showing a sixth embodiment of the present invention.

FIG. 13 is a diagram showing a seventh embodiment of the present invention.

FIG. 14 is a diagram showing an eighth embodiment of the present invention.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C01B 3/56 C01B 3/56 Z H01M 8/10 H01M 8/10 8/12 8/12 F term (reference) 4D020 AA03 BA01 BA03 BA08 BB01 BC01 CA01 4G040 BA02 BB03 EA03 EA06 EB12 EB32 EB33 EB42 EB44 FA02 FB04 FC02 FD07 FE01 5H026 AA06 5H027 AA06 BA09 BA16 BA17 BA19

Claims (8)

[Claims] [Claim 1] The off-gas of the solid oxide fuel cell to a system for producing hydrogen through a CO shift converter, CO ₂ removal through a modified gas in the CO transformer to CO ₂ absorbent layer A high-purity hydrogen production system characterized in that: 2. A fuel cell system, wherein high-purity hydrogen obtained by the high-purity hydrogen production system according to claim 1 is used as a fuel for a polymer electrolyte fuel cell. 3. A system in which hydrocarbons are reformed by steam reforming using excess heat of a solid oxide fuel cell, and hydrogen is produced through a CO converter, wherein the CO is converted by the CO converter. A high-purity hydrogen production system characterized in that CO ₂ is removed by passing a gas through a CO ₂ absorbent layer. 4. A fuel cell system, wherein high-purity hydrogen obtained by the high-purity hydrogen production system according to claim 3 is used as a fuel for a polymer electrolyte fuel cell. 5. A system for producing hydrocarbons by reforming hydrocarbons by steam reforming using combustion heat generated by burning off-gas of a polymer electrolyte fuel cell and passing the reformed CO through a CO converter. A high-purity hydrogen production system, characterized in that a gas converted in a shift converter is passed through a CO ₂ absorbent layer to remove CO ₂ . 6. A fuel cell system, wherein high-purity hydrogen obtained by the high-purity hydrogen production system according to claim 5 is used as a fuel for a polymer electrolyte fuel cell. 7. A system for producing hydrocarbons by reforming hydrocarbons by steam reforming using combustion heat generated by burning off-gas of a polymer electrolyte fuel cell, and passing the reformed hydrocarbons through a CO converter. after removal of CO ₂ through the off-gas to CO ₂ absorber layer, with burning, and characterized in that the modified gas in the CO transformer becomes followed by removal of CO ₂ through CO ₂ absorbent layer High-purity hydrogen production system. 8. A fuel cell system, wherein high-purity hydrogen obtained by the high-purity hydrogen production system according to claim 7 is used as a fuel for a polymer electrolyte fuel cell.