JPH06321503A - Apparatus for hydrogen production - Google Patents

Abstract

(57) [Abstract] [Purpose] We have developed a laboratory-scale hydrogen generator that is designed to separate hydrogen produced by a steam reforming reaction by permeating a selective hydrogen-permeable partition wall. An industrial hydrogen production device having a novel structure is provided. [Structure] The hydrogen production apparatus 10 includes an outer cylinder 1 with a bottom 12 closed.
4, the inner cylinder 16 and the inner cylinder 18 that are sequentially arranged inside
It has and. The outer cylinder 14, the middle cylinder 16, and the inner cylinder 18 each have an upright cylindrical shape. A catalyst layer 26 filled with the reforming catalyst A is formed in the second annular space 26 between the middle cylinder and the inner cylinder, and the catalyst layer 26 is provided with a metal membrane that selectively permeates hydrogen. The rectangular parallelepiped 34 is arranged concentrically with the second annular space 26. Further, a large number of sweep gas pipes 3 are provided in the third space 33 defined by the outer wall and the inner wall of the hydrogen-permeable rectangular parallelepiped 34.
Charge 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing hydrogen from a mixed gas of hydrocarbon or methanol and steam by a steam reforming reaction, and more particularly to a solid polymer fuel cell (polymer fuel cell). The present invention relates to an industrial-scale hydrogen production apparatus capable of obtaining such high-purity hydrogen at a low reaction temperature.

[0002]

2. Description of the Related Art Hydrogen used in fuel cells, particularly polymer electrolyte fuel cells, preferably has a CO content of 10 ppm or less. Therefore, hydrogen obtained from naphtha, natural gas, city gas, etc. using the steam reforming reaction is unsuitable for fuel cells because the hydrogen purity is low as it is. Was further purified by passing it through a carbon monoxide shift converter and a hydrogen purifier to bring the hydrogen purity to a desired value. However, the above-mentioned process for producing high-purity hydrogen has complicated production steps, requires high-temperature and high-pressure equipment for the process, and consumes a large amount of high-temperature heat energy, resulting in high production cost of high-purity hydrogen. However, it was not economical to put it into practical use as hydrogen for fuel cells.

Therefore, as disclosed in documents such as JP-A-61-17401, it has been proposed to obtain high-purity hydrogen by using a permeable membrane that selectively permeates hydrogen. Came. For example, the above-mentioned publication is CH ₄ /
A method and apparatus for continuously separating produced hydrogen from a reaction space at a temperature of 500 to 1,000 ° C. through a selective hydrogen permeable partition wall in a H ₂ O reforming reaction or a water gas generation reaction. It discloses and describes that high purity hydrogen can be separated. Further, publicly known documents including the above-mentioned publications disclose a laboratory-scale hydrogen production apparatus whose principle is shown in FIG. 6, for example. In the conventional hydrogen generator of FIG. 6, 90 is a reaction tube, 92 is a reforming catalyst layer, and 94 is
Is a hydrogen permeation tube, a mixed gas of hydrocarbon and water vapor is introduced from the lower arrow X, is reformed by the reforming catalyst layer 92 to generate hydrogen gas, and this hydrogen gas permeates the hydrogen permeation tube 94. Flow out from the upper arrow Y, and the unreacted gas flows into the arrow Z
Drained from.

[0004]

However, the known document hardly discloses a method or means for scaling up such a laboratory scale device to an industrial scale device. In other words, how to practically use the method of continuously separating the produced hydrogen through the hydrogen-permeable partition wall as an industrial-scale technique, or to use such a laboratory-scale apparatus for industrial-scale large-scale hydrogen It is a technology that has not yet been established as to how to expand to manufacturing equipment.

By the way, in order to scale up the technology on a laboratory scale to a large-scale hydrogen production apparatus on an industrial scale, it is necessary to overcome various technical problems and establish economical efficiency as a hydrogen production apparatus. For example, as shown in FIG. 6, a large number of reaction tubes equipped with hydrogen permeation tubes may be arranged in parallel in a reforming catalyst layer, and inlets and outlets of the reaction tubes may be connected by headers to form a multitubular reactor. This is one of the methods for increasing the size. But,
Since such a device has a large size and a complicated structure, it becomes a device having poor operability and controllability and low thermal efficiency, and requires a large amount of material for construction, and is economically costly and not competitive. Become. Similarly, engineering problems such as the structure of the separation means having a hydrogen permeable membrane or the structure of the heating means for heating the reaction region are extremely important problems in scaling up the equipment. However, no specific example is shown.

On the other hand, in order to put the fuel cell into practical use, it is extremely important that high-purity hydrogen can be provided at a low cost.
In response to such a demand, it has been a pending issue to realize an industrial-scale hydrogen production apparatus capable of producing high-purity hydrogen at a low cost. In view of the above-mentioned problems, an object of the present invention is to develop a laboratory-scale hydrogen production apparatus adapted to permeate a selective hydrogen-permeable partition wall to separate and collect hydrogen produced by a steam reforming reaction. Accordingly, it is an object of the present invention to provide an industrial hydrogen production device having a novel structure.

[0007]

In order to achieve the above-mentioned object, the hydrogen producing apparatus according to the present invention comprises: (1) hydrogen produced by a steam reforming reaction by passing through a selective hydrogen-permeable partition wall. In a hydrogen production device configured to separate and collect, an upright outer cylinder with a closed bottom, a middle cylinder and an inner cylinder that are vertically arranged inside and vertically arranged in sequence, and are arranged on the ceiling wall of the inner cylinder. The first annular space portion defining the outer cylinder and the middle cylinder and the inner cylinder hollow portion inside the inner cylinder communicate with each other at their bottoms, and further, the middle cylinder and the inner cylinder. The cylinder forms a second annular space portion having a closed annular bottom portion in which lower end edges are connected to each other, and a catalyst layer filled with a reforming catalyst is formed in the second annular space portion. The layer comprises an outer wall and an inner wall having a hydrogen permeable metal membrane on the inorganic porous layer, a side wall and a bottom wall. A hydrogen permeating rectangular parallelepiped defining a third space, and a sweep gas pipe having an open lower end is arranged in the third space, and the raw material gas is introduced from the upper part of the second annular space. While flowing down the catalyst layer, it is converted to hydrogen at a high temperature, the generated hydrogen is permeated through a hydrogen permeation rectangular parallelepiped, and is selectively separated and collected, and the permeated hydrogen is entrained in the sweep gas introduced from the upper part of the sweep gas pipe. A hydrogen production device, characterized in that the hydrogen production device is made to flow out together with the sweep gas from the upper part via the third space part. (2) The hydrogen-permeable metal film is an alloy containing Pd, N
The hydrogen generating apparatus according to (1) above, which is a non-porous thin film of either an alloy containing i or an alloy containing V. (3) In the hydrogen production device according to (1) above, instead of the permeated hydrogen collection method involving the sweep gas, the permeated hydrogen is collected by scavenging the hydrogen permeation side with a pump. Hydrogen production equipment characterized by. (4) In the hydrogen generator described in (1) or (2) above, the flow directions of the raw material gas and the sweep gas are set to be opposite to each other. (1) or (2) Hydrogen production device described in. (5) The hydrogen production device as described in any one of (1) to (4) above, wherein the upper and lower positions are installed in opposite directions, and the hydrogen production device is any one of (1) to (4) above. Hydrogen production equipment. Is.

[0008]

The raw material gas introduced into the hydrogen production apparatus according to the present invention is a mixture of light hydrocarbons such as natural gas, naphtha and city gas and alcohol such as methanol with water vapor. Further, as the reforming catalyst used in the present invention, any catalyst which has been conventionally used when hydrogen is produced from the above-mentioned raw material gas by the steam reforming method can be used.

The hydrogen producing apparatus of the present invention is composed of a multi-cylinder body in which a vertical furnace is formed by an inner cylinder, and on the outer side thereof, a cylindrical body of an upright middle cylinder and an outer cylinder is sequentially arranged. Further, the second annular space is filled with a reforming catalyst to form a catalyst layer, and a hydrogen permeating rectangular parallelepiped is arranged in the catalyst layer to form a reaction / separation region. Suitably, each tubular body is a cylindrical body. Due to the concentric multi-cylinder body in which the furnace is arranged in the central portion, the heat flux distribution in the radial direction becomes uniform, and it is possible to prevent the occurrence of hot spots that exceed the heat resistant temperature of the hydrogen permeation rectangular parallelepiped.

The heat required to maintain the endothermic steam reforming reaction is supplied by a hanging combustion burner mounted on the cylindrical ceiling wall. The drooping combustion burner is a type of burner in which the flame is directed downward, and the conventionally used burner can be used.

The hydrogen-permeable rectangular parallelepiped comprising a hydrogen-permeable wall provided with a hydrogen-permeable metal film on the inorganic porous layer is a so-called membrane reactor that selectively permeates only hydrogen, but is used in the present invention. The hydrogen permeable rectangular parallelepiped is provided with an inner wall and an outer wall having a hydrogen permeable metal film that can be easily formed, and is devised so as to be a more economical membrane reactor.

Taking methane as an example of the hydrocarbon, the action of the hydrogen permeable wall will be explained. Reforming reaction of methane is 500
A chemical equilibrium is reached by proceeding according to the following equation at a reaction temperature in the range of ℃ to 1,000 ℃.

[0013]

[Chemical 1]

Here, hydrogen produced from the product is passed through the hydrogen permeable wall.
To lower the partial pressure of hydrogen in the product by selective separation.
Then, in the above formula, the reaction proceeds further to the right, resulting in
At the same reaction temperature, the conversion rate increases. In other words,
In the conventional methane reforming method, the temperature in the reaction zone is set to about 800 ° C.
It was necessary to use a hydrogen permeable wall
Therefore, in the hydrogen production device according to the present invention, the conversion rate of the same value
Can be achieved at temperatures of 500-600 ° C. Na
Oh, per unit area of hydrogen permeable metal membrane of hydrogen permeable wall
Hydrogen permeation amount Q_HIs the square root of the hydrogen partial pressure on the non-permeate side (P
h)^1/2And square root of hydrogen partial pressure on permeate side (Pl) ^1/2With
Proportional to the difference. That is, Q_H= K {(Ph)^1/2−
(Pl)^1/2}.

As described above, since hydrogen can be collected by the hydrogen permeable wall and the chemical reaction can be shifted to the right side in the above equation, the reforming temperature is lowered by about 150 to 200 ° C.
As a result, the amount of heat for heating the reaction gas is reduced, and the thermal efficiency is significantly improved. In addition, since the reaction temperature is low, an inexpensive material that does not have high heat resistance can be used for the device, and thus the cost of the device can be reduced.

The sweep gas flows countercurrent to the reformed gas flowing through the catalyst layer. Therefore, in the vicinity of the catalyst layer outlet end, the generated hydrogen is almost completely swept and the hydrogen partial pressure is greatly reduced, so that the introduction of the sweep gas has the effect of increasing the conversion rate in the entire catalyst layer. Further, the recovery rate of produced hydrogen can be increased by countercurrent mass transfer of the sweep gas in the hydrogen-permeable rectangular parallelepiped and the reformed gas in the catalyst layer. Examples of the sweep gas used in the hydrogen production apparatus of the present invention include steam, and inert gases such as nitrogen and helium.

Since the hydrogen-permeable metal film of the hydrogen-permeable rectangular parallelepiped selectively permeates only hydrogen, the purity of hydrogen separated by the hydrogen-permeable rectangular parallelepiped is extremely high, and it is most suitable as hydrogen for the above-mentioned solid polymer fuel cell. Is.

The hydrogen permeable metal film has a thickness of 5 to 50.
It is μm, and it is formed on the inorganic porous layer and can selectively permeate hydrogen. The inorganic porous layer thereunder is a carrier for holding the hydrogen-permeable metal film, and is formed of a porous stainless steel nonwoven fabric, ceramics, glass or the like having a thickness of 0.1 mm to 1 mm. Further, a wire net composed of a single layer or a plurality of layers is arranged inside the structure as a structural strength member.

In a preferred embodiment of the present invention, the hydrogen-permeable metal film is preferably a non-porous layer made of an alloy containing Pd, an alloy containing Ni, or an alloy containing V.
Pd / Ag alloy, Pd / Y alloy, P
Examples thereof include d.Ag.Au alloys, examples of _V- containing alloys include V.Ni and V.Ni.Co, and examples of Ni-containing alloys include LaNi.sub.5. . A method for producing a non-porous Pd layer is disclosed in, for example, US Pat. Nos. 3,155,467 and 277,361.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in more detail based on embodiments with reference to the accompanying drawings. (Embodiment 1) FIG. 1 is a perspective sectional view of Embodiment 1 of a hydrogen production apparatus according to the present invention, FIG. 2 is a schematic cross-sectional view of the hydrogen production apparatus of FIG. 1, and FIG. 3 is a detailed sectional view of a hydrogen-permeable rectangular parallelepiped. Is. As shown in FIGS. 1 and 2, the hydrogen production apparatus 10 has a bottom 12
And an inner cylinder 16 and an inner cylinder 18 sequentially and concentrically arranged inside thereof. In this embodiment, the outer cylinder 14, the middle cylinder 16 and the inner cylinder 18 each have an upright cylindrical shape.

The outer cylinder 14 and the middle cylinder 16 define a first annular space portion 20 between the cylinder walls thereof, and the first annular space portion 20 and the inner cylinder hollow portion 22 inside the inner cylinder 18 respectively. It communicates with the bottom of. The middle cylinder 16 and the inner cylinder 18 form a closed annular bottom portion 24 by connecting lower end edges to each other and also form a second annular space portion 26 between the cylinder walls. The inner cylinder hollow part 22, the space between the bottom part 12 of the outer cylinder 14 and the annular bottom part 24, and the continuous space part consisting of the first annular space part 20 form a flow path of combustion gas, and the outer cylinder wall 14 And the bottom wall 12 of the outer cylinder 14
Each is constructed of refractory bricks.

In the second annular space 26, a catalyst layer 26 filled with the reforming catalyst A (for convenience, the same reference numeral as that of the second annular space) is formed. Further, the catalyst layer has a structure shown in FIG.
As shown in FIG. 3, it comprises an outer wall 28, an inner wall 30, a bottom wall 32 (see FIG. 3), and a side wall 36 each having a hydrogen permeable metal film on the inorganic porous layer, thereby defining a third space 33. The hydrogen permeable wall of the hydrogen permeable rectangular parallelepiped 34 is arranged concentrically with the second annular space portion 26. Hydrogen Permeation Box 34
Inside, a large number of cylindrical sweep gas pipes 38 made of stainless steel are arranged substantially in the center of the hydrogen-permeable rectangular parallelepiped 34.

As shown in FIG. 3, the outer wall 28, the inner wall 30 and the bottom wall 32 of the hydrogen permeable rectangular parallelepiped 34 are each provided with a stainless steel mesh 39 as a supporting member on the inside thereof, and a hydrogen permeable metal film carrier thereon. Is provided with an inorganic porous layer 40 made of a stainless steel nonwoven fabric, and a non-porous Pd film 42 is further coated thereon as a hydrogen permeable metal film. It is an important feature that the hydrogen-permeable rectangular parallelepiped in Example 1 is easier to form than other structures.

Ceiling wall 4 that closes the top of the inner cylinder hollow portion 22
4, a hanging combustion burner 46 is attached downward. A fuel gas pipe 48 and an air intake pipe 50 are connected to the combustion burner 46.

Next, the process of the hydrogen producing apparatus 10 will be described with reference to FIGS. 1 and 2. The combustion burner 46 burns the fuel gas introduced through the fuel gas pipe 48 by the air taken through the air intake pipe 50 to supply the thermal energy required for the steam reforming reaction to the catalyst layer 26. To maintain a predetermined temperature. Combustion gas is the inner cylinder hollow part 2
2, the space between the bottom 12 of the outer cylinder 14 and the annular bottom 24,
Then, the gas exits from the combustion gas outlet 52 through the first annular space 20. Meanwhile, the catalyst layer 26 is heated.

A process feed gas consisting of a light hydrocarbon or a mixed gas of methanol gas and steam is provided at an upper portion of the second annular space 26, and a feed gas inlet 54 is provided.
Is introduced into the catalyst layer 26 and is converted into hydrogen at a high temperature. The produced hydrogen is selectively separated and collected by the hydrogen rectangular parallelepiped 34, and flows out together with the sweep gas from the hydrogen outlet 56 provided at the upper part of the hydrogen through the third space 33.

The sweep gas is fed from the sweep gas inlet 58 at the upper part of the apparatus, flows down the sweep gas pipe 38, then flows into the third space 33 from the lower end opening, and the produced hydrogen is accompanied while sweeping hydrogen. It rises and flows out from the hydrogen outlet 56. The partial pressure of hydrogen on the permeate side of the hydrogen permeation tube 32 is kept low by causing the sweep gas to flow out together with the hydrogen so that the hydrogen is pushed away. As the sweep gas, for example, steam or inert gas is used. On the other hand, the catalyst layer 2
Unreacted raw material gas passing through 6, generated CO, CO ₂
The gas is an offgas pipe 60 having an opening at the bottom of the catalyst layer 26.
Via the off-gas outlet 62 via.

In the above-mentioned embodiment, the raw material gas flows downward from the upper part of the second annular space, while the sweep gas is introduced from the upper part of the sweep gas pipe and taken out together with the entrained hydrogen from the upper part of the sweep gas pipe through the third space. However, it is clear that the same effect can be expected by reversing the flow directions of the raw material gas and the sweep gas.

Further, in the above-described embodiment, it is obvious that the same effect can be expected by installing the upper and lower positions of the hydrogen producing device in opposite directions.

(Second Embodiment) FIG. 4 shows a second embodiment according to the present invention.
FIG. 5 is a perspective sectional view of the hydrogen producing apparatus 110 of FIG. 5, and FIG. 5 is a transverse sectional view of the hydrogen producing apparatus 110 shown in FIG. The difference from the first embodiment is the arrangement direction of the hydrogen-permeable rectangular parallelepiped 34.
The hydrogen-permeable rectangular parallelepiped 34 is composed of a wall 28, a wall 30, a bottom wall 32, and a side wall 36 having a hydrogen-permeable metal film on an inorganic porous layer, thereby defining the third space 33. Is arranged radially in the second annular space portion 26, and the hydrogen producing apparatus 110 of the embodiment is the same as the hydrogen producing apparatus 1 of the first embodiment except for the above-mentioned different points.
It has the same configuration as 0.

The hydrogen-permeable metal film of Example 2 is arranged radially from the central part of the furnace, and it is possible to prevent the generation of hot spots that exceed the heat resistant temperature of the hydrogen-permeable metal film. Even if the number is reduced, the area of the hydrogen-permeable metal film equivalent to that in Example 1 can be obtained, which is advantageous for downsizing.

[0032]

INDUSTRIAL APPLICABILITY The present invention realizes an industrial-scale hydrogen production apparatus that economically produces high-purity hydrogen, with the following advantages obtained by the above-described configuration. (A) Since the device is composed of a hydrogen-permeable rectangular parallelepiped and a multi-cylinder, the structure is simple and compact. Therefore,
The hydrogen production device of the present invention can be economically constructed with a small number of materials. (B) Since the catalyst layer is heated from both sides, the catalyst layer can be heated more uniformly. Further, the heat flux distribution in the radial direction becomes uniform due to the configuration of the multi-cylinder body in which the furnace is arranged in the central portion. Therefore, it is possible to prevent the occurrence of hot spots that exceed the heat resistant temperature of the hydrogen-permeable cuboid. (C) Hydrogen Permeation The countercurrent mass transfer between the sweep gas in the rectangular parallelepiped and the reformed gas in the catalyst layer can increase the recovery rate of produced hydrogen. (D) Since hydrogen can be separated and collected by a hydrogen-permeable rectangular parallelepiped and chemical equilibrium can be advantageously transferred to production of a product,
The reforming temperature can be lowered by about 150 to 200 ° C. As a result, the amount of heat for heating the raw material gas can be reduced, and the thermal efficiency can be greatly improved. (E) Further, since the reaction temperature is low, an inexpensive material having high heat resistance can be used for the device. Therefore, the cost of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective cross-sectional view of a first embodiment of a hydrogen production device according to the present invention.

FIG. 2 is a schematic cross-sectional view of the hydrogen production device of FIG.

3 is a partial cross-sectional view of a hydrogen-permeable rectangular parallelepiped taken along line XX in FIG.

FIG. 4 is a perspective sectional view of Embodiment 2 of the hydrogen production device according to the present invention.

5 is a schematic cross-sectional view of the hydrogen production device shown in FIG.

FIG. 6 is a schematic structural diagram of a laboratory-scale apparatus for a conventional hydrogen production apparatus.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Uchida 3-2-15-106 Azamino, Midori-ku, Yokohama-shi, Kanagawa (72) Inventor Takashi Mayo 4-6-22 Kannon-shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries Inside the Hiroshima Plant (72) Inventor Shinsuke Ota 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries Ltd. Inside the Hiroshima Plant (72) Kennosuke Kuroda 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd.

Claims (5)

[Claims] 1. A hydrogen production apparatus configured to separate and collect hydrogen produced by a steam reforming reaction by permeating a partition wall selectively permeable to hydrogen, and an upright outer cylinder having a closed bottom and an inner side thereof. A first and a middle cylinder and an inner cylinder, which are vertically and sequentially arranged in multiple layers, and a hanging combustion burner arranged on a ceiling wall of the inner cylinder, and which defines an outer cylinder and a middle cylinder. The annular space portion and the inner cylinder hollow portion on the inner side of the inner cylinder communicate with each other at their bottom portions, and the middle cylinder and the inner cylinder have a second annular space portion having a closed annular bottom portion whose lower edges are connected to each other. And a catalyst layer filled with a reforming catalyst is formed in the second annular space, and the catalyst layer has an outer wall, an inner wall, a side wall and a bottom having a hydrogen permeable metal film on the inorganic porous layer. A sweeper with a wall and a hydrogen-permeable rectangular parallelepiped defining the third space is arranged, and the lower end is opened. The gas pipe is arranged in the third space, and the raw material gas is introduced from the upper part of the second annular space to convert it into hydrogen at a high temperature while flowing down the catalyst layer, and the generated hydrogen permeates through the hydrogen permeation rectangular parallelepiped. By selectively separating and collecting the permeated hydrogen, the permeated hydrogen is entrained in the sweep gas introduced from the upper part of the sweep gas pipe, and flows out from the upper part through the third space part together with the sweep gas. Hydrogen production equipment characterized by. 2. The hydrogen according to claim 1, wherein the hydrogen-permeable metal film is a non-porous thin film of any one of an alloy containing Pd, an alloy containing Ni, and an alloy containing V. Manufacturing equipment. 3. The hydrogen production apparatus according to claim 1, wherein the permeated hydrogen is collected by scavenging the hydrogen permeation side with a pump instead of the permeated hydrogen collection method of the sweep gas entrainment type. A hydrogen production device characterized by the above. 4. The hydrogen production apparatus according to claim 1 or 2, wherein the flow directions of the raw material gas and the sweep gas are set to be opposite to each other. The hydrogen production apparatus described in 1. 5. The hydrogen production apparatus according to any one of claims 1 to 4, wherein the upper and lower positions are installed in opposite directions. Hydrogen production equipment.