JPH06345407A - Hydrogen production device - Google Patents

Abstract

PURPOSE:To provide a compact hydrogen production device capable of producing high-purity hydrogen by carrying out each reaction in a reforming device, a carbon monoxide transformer and a hydrogen purifier collectively. CONSTITUTION:In a device for producing hydrogen by steam modifying reaction from a hydrocarbon and/or an alcohol, the production device is equipped with an upright cylindrical closed case 1 having an outlet 1a of an exhaust gas of combustion, plural cylindrical reaction tubes 3 standing in the case, a multi- burner 2 above the reaction tubes in the case and a manifold 4 laid at the bottom of the case. The reaction tubes 3 have an upright raw material feed pipe 10 which has the top opening to the inside of the reaction tube and the lower end led to a feed opening 10a of a raw material, an upright hydrogen taking out pipe 11 which covers the outer peripheral side of the feed pipe of the raw material, has the open top and the lower end led to a hydrogen outlet 11a and an upright closed hydrogen permeating pipe 12 which covers the outer periphery of the hydrogen taking out pipe, has the closed top and the lower end led to a feed opening 12a of a sweeping gas. A reforming catalyst 5 is packed between a hydrogen permeating pipe and the reaction tubes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for steam reforming hydrocarbons and / or alcohols to produce hydrogen.

[0002]

2. Description of the Related Art A method of producing hydrogen in a reformer by utilizing a steam reforming reaction from hydrocarbons and / or alcohols is widely used in industry. On the other hand, in a fuel cell that operates at about 200 ° C or lower, the catalyst such as platinum in the electrode is C
Since it is poisoned by O, the CO concentration in the hydrogen-containing gas supplied to the fuel cell must be 1% or less. Two
As a fuel cell that operates at a relatively low temperature of 00 ° C or lower,
In the phosphoric acid type that operates at 150 to 230 ° C. and the solid polymer membrane type that operates at 100 ° C. or less, it is said that the CO concentration in the hydrogen-containing gas supplied to the fuel cell needs to be 10 ppm or less. Therefore, in order to use hydrogen produced by the conventional method as a fuel gas for a fuel cell, the crude hydrogen is further purified by a carbon monoxide shift converter and a hydrogen purifier to have a high purity (about CO 10 ppm or less). It is considered to be used for a molecular membrane fuel cell (polymer fuel cell). The reaction that takes place in this case is as follows in the case of methane.

[0003]

However, the above-mentioned process for purifying hydrogen with high purity has complicated steps, the entire apparatus is large, requires a large amount of high-temperature heat energy, and the efficiency of the apparatus is high. Has a drawback that the hydrogen production cost is inevitably high, and it has almost no carbon monoxide (approximately 10 ppm or less CO), which is high purity, such as that supplied directly from a city gas to a solid polymer membrane fuel cell. It is extremely difficult to produce such hydrogen in consideration of economical efficiency.

Therefore, the concept of a membrane reactor that simultaneously processes a reforming reaction and hydrogen purification by making a hydrogen separation membrane (membrane) that selectively permeates hydrogen coexist with a reforming reaction field has already been disclosed in Japanese Patent Laid-Open No. 61-61. -17401 and Japanese Patent Laid-Open No. 4-321502. However, in these prior applications, only the basic principle of the reactor is proposed, and practical examples of a practical reactor configuration that is easy to increase in size, particularly a heating system and a supply / discharge system of each fluid are not shown. That is, in these prior applications, FIG.
As shown in Fig. 5, a hydrogen permeation tube that selectively permeates hydrogen is used as the inner tube, and the catalytic reaction tube is placed as the outer tube in a concentric cylindrical shape on the outside, and an annular space between the inner tube and the outer tube is modified. It has only been shown to be loaded with a quality catalyst and to heat the outer tube wall with a suitable heating medium.

The present invention has been made in consideration of the above points, and the reactions of the reformer, the carbon monoxide shift converter and the hydrogen purifier used in the conventional process are collectively carried out,
An object of the present invention is to provide a compact hydrogen production device capable of producing high-purity hydrogen.

[0006]

In order to solve the above-mentioned problems, the present invention is an apparatus for producing hydrogen from hydrocarbons and / or alcohols by a steam reforming reaction, and is an upright cylindrical hermetic seal having a combustion exhaust gas discharge port in the lower part. A case,
A cylindrical reaction tube having a plurality of upright heads sealed inside the case, a burner provided above the reaction tube inside the case, and a manifold provided at the bottom of the case. The reaction tube has an upper end opening inside the reaction tube and a lower end communicating with a raw material supply port of the manifold, and an upright cylindrical raw material supply pipe surrounding the outer peripheral side surface of the raw material supply pipe and having an upper end opened and a lower end. Is an upright cylindrical hydrogen extraction pipe communicating with the hydrogen discharge port of the manifold, and an upright cylindrical hydrogen permeation pipe surrounding the outer circumference of the hydrogen extraction pipe and having an upper end closed and a lower end communicating with the sweep gas supply port of the manifold. And a reforming catalyst is filled between the hydrogen permeation tube and the reaction tube.

[0007]

The hydrogen producing apparatus of the present invention is a hydrogen permeable membrane type reformer composed of a reforming catalyst, a hydrogen permeable tube (palladium thin film and palladium alloy, etc.), a heating burner, etc. High-purity hydrogen can be produced directly from alcohols. That is, high-purity hydrogen can be easily obtained by penetrating the catalyst layer in the reaction tube and providing the hydrogen permeation tube. A burner is provided on the ceiling, and high-temperature combustion exhaust gas from this burner is poured down from above each reaction tube to evenly transfer convection heat and conduction heat to each reaction tube. The sweep gas is supplied as an upward flow and becomes a counter flow to the downward flow of gas in the catalyst layer, so that hydrogen permeation is efficiently performed. Also, because the chemical equilibrium shifts by using a hydrogen permeation tube,
The reforming temperature (700 to 800 ° C) can be lowered by 150 to 200 ° C.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical cross-sectional view showing a schematic structure of the hydrogen production apparatus of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

A cylindrical closed case 1 is upright. A combustion gas discharge port 1a is provided at the bottom of the case 1.

A multi-burner 2 is arranged on the ceiling inside the case 1. The multi-burner 2 has a large number of nozzles 2a on its lower surface, and the nozzles 2a can eject a short flame 2b downward.

A manifold 4 is provided below the case 1. Details of the manifold 4 will be described later.

Inside the case 1, a plurality of (7 in the illustrated embodiment) cylindrical head-sealed reaction tubes 3 which are evenly distributed on the manifold 4 are vertically installed. . In order to prevent the flame 2b ejected from the multi-burner 2 from directly touching the head of the reaction tube 3, it is preferable to displace the nozzle 2a and the reaction tube 3 from the position directly above, as shown in FIG. Next, the details of the reaction tube 3 will be described.

FIG. 3 is an enlarged view of a part of FIG. 1, showing the details of the reaction tube 3.

As described above, the reaction tube 3 is an upright cylindrical closed tank, the ceiling of which is closed and the lower end of which is connected to the offgas discharge port 3a. Inside the reaction tube 3, a raw material supply tube 10 serving as a center, a hydrogen extraction tube 11 outside thereof,
Further, the hydrogen permeation tube 12 on the outside thereof is included. These tubes 10, 11 and 12 are arranged diametrically spaced apart from each other and concentrically in an upright position. The hydrogen permeation tube 12 is made of a porous carrier prepared by depositing palladium on the porous carrier by an electroless plating method, and the other members are mainly made of stainless steel.

The raw material supply pipe 10 has an upper end open to the inside of the reaction tube 3 and a lower end communicating with the raw material supply port 10a.

The hydrogen extraction pipe 11 surrounds the outer circumference of the raw material supply pipe 10, has an upper end opened inside the hydrogen permeation pipe 12, and a lower end communicated with the hydrogen discharge port 11a.

The hydrogen permeation tube 12 encloses the outer periphery and the ceiling of the hydrogen extraction tube 11 in a hermetically sealed manner with a gap between them.
The lower end communicates with the sweep gas supply port 12a.

City gas and water vapor used as raw materials are manifold 4
From the raw material supply port 10a to the raw material supply pipe 10 and is blown upward from a hole in the center of the lower part of the hydrogen production apparatus, and the sweep gas enters the hydrogen permeation pipe 12 from the sweep gas supply port 12a of the manifold 4 and It is blown up from the annular entrance. The mixture of hydrogen and the sweep gas and the off gas are discharged from the respective annular outlets at the center of the lower part of the apparatus through the manifold 4.

Combustion exhaust gas discharge port 1a of case 1, process off gas discharge port 3a of reaction tube 3, sweep gas supply port 12a of hydrogen permeation tube 12, hydrogen discharge port 11a of hydrogen extraction tube 11, raw material supply tube 10 All the mouths 10a are put together in the manifold 4. The process off gas is a residual gas obtained by permeating and removing hydrogen from the generated gas, and the sweep gas is a gas for scavenging the hydrogen generated in the hydrogen permeation pipe 12.

A reforming catalyst 5 is filled in the gap between the hydrogen permeation tube 12 and each reaction tube 3. As the reforming catalyst, a catalyst containing a Group VIII metal (Fe, Co, Ni, Ru, Rh, Pd, Pt, etc.) is preferable, and a catalyst supporting Ni, Ru, Rh or a NiO-containing catalyst is particularly preferable.

The hydrogen production apparatus of the present invention having the above-mentioned structure operates as follows.

The fuel supplied from below is supplied to the multi-burner 1
Combustion in this way produces high temperature combustion exhaust gas. The combustion exhaust gas flows down in the direction of arrow D from the top of each reaction tube 3, flows between them, and transfers heat to each reaction tube 3.
Thus, the reforming catalyst 5 in each reaction tube 3 and the reforming gas as the reaction fluid are heated, and the steam reforming reaction is performed. The combustion exhaust gas is exhausted to the outside from the exhaust port 1a of the manifold 4.

The sweep gas is supplied to the supply port 12 of the manifold 4.
It is sent from a into the hydrogen permeation tube 12 in the direction of arrow B.

A mixture of methane and the like as a raw material gas and water vapor is fed from the supply port 10a of the manifold 4 in the direction of arrow A, and penetrates from the upper portion of the reforming catalyst 5 of each reaction tube 3 through the raw material supply pipe 10. . While passing through the inside of the reforming catalyst 5, the source gas such as methane is steam-reformed with the heat generated by the combustion of the fuel gas to generate hydrogen. The reaction formula at this time is as follows, when an example of methane is shown. The produced hydrogen permeates into the hydrogen permeation pipe 12 in the direction of arrow C, and rises in the direction of arrow B along with the sweep gas, and then advances through the hydrogen extraction pipe 11 in the direction of arrow E to exhaust the manifold 4. It is pushed out from the outlet 11a in the direction of arrow E.

Further, the off gas such as carbon dioxide gas in the reaction tube 3 is discharged from the discharge port 3a of the manifold 4 in the direction of arrow F to the outside. At this time, the discharge direction (downward) of the off gas in the packed bed of the reforming catalyst 5 is opposite to the inflow direction (upward) of the sweep gas in the hydrogen permeation tube 12,
Hydrogen can be efficiently permeated to the hydrogen permeation pipe 12 from the reformed gas flowing in the packed bed of the reforming catalyst 5.

The number of reaction tubes 3 used in the apparatus of the above embodiment can be increased or decreased as necessary. Further, although an example using a multi-burner is shown in the above-mentioned embodiment, it is needless to say that the same effect can be obtained by using a single burner having equivalent characteristics.

Inverting the apparatus of the above embodiment, the fuel is blown into the burner from the lower side for combustion, and the sweep gas, the raw material gas, and the steam are introduced from the upper portion, and the hydrogen and the off gas are discharged from the upper portion. You can also

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below. (1) Equipment configuration Reaction tube 3 (inner diameter 35.5 mm) Hydrogen permeation tube 12 (outer diameter 20 mm) Hydrogen extraction tube 11 (outer diameter 12 mm) Raw material supply pipe 10 (outer diameter 6 mm) Effective length 1000 mm
The reaction tube structure of multiple concentric cylinders was constructed, and a total of 6 of these were placed upright inside the case 4 having an inner diameter of 180 mm and an effective height of 1200 mm. That is, 1 on the center axis of case 4
The five books and the other five books were arranged at equal intervals in the outer circumferential direction. The hydrogen permeation tube 12 was a membrane made of a palladium-based thin film, and the reforming catalyst 5 was a nickel-based catalyst (average particle diameter 2 mmφ). In order to reduce heat radiation to the outside air, the outside of the case 4 has a thickness of 1
It was kept warm with 50 mm rock wool. (2) Operating conditions-Source gas supply rate: Methane 0.35 Nm ³ / h-Reforming steam supply rate: 1.05 Nm ³ / h (steam / methane molar ratio S / C = 3.1) -Sweep gas (Steam) supply rate: 1.4 kg / h ・ Sweep gas pressure: atmospheric pressure ・ Catalyst layer temperature: 540 to 550 ° C ・ Catalyst layer pressure: 6.5 kg / cm ² -abs. The combustion conditions on the burner side are catalyst The average temperature of the layers was adjusted to the values given above. (3) Results of hydrogen generation test Under the above-mentioned operating conditions, the amount of hydrogen obtained by entraining methane 0.35 Nm ³ / h in the sweep gas was 1.01 Nm ³ / h, and impurities in hydrogen were found. As C
O was 1 ppm or less. A reaction conversion rate of methane of about 81% was also achieved. In a conventional reformer that does not employ a hydrogen permeation tube, the conversion rate is 25% due to the chemical equilibrium wall due to the relationship between operating temperature and pressure.

[0031]

As described above, according to the present invention, a plurality of cylindrical reaction tubes are installed inside an upright cylindrical closed case, and a raw material supply tube and a hydrogen extraction tube are concentrically provided in the reaction tube. And a hydrogen permeation tube are included, high-temperature combustion exhaust gas is poured from a multi-burner provided above the reaction tube to heat the reaction tube, and raw materials are supplied from a manifold provided at the bottom of the case, and the exhaust gas is also discharged. Is configured to be discharged from this manifold, the following excellent effects can be obtained. (1) By using a hydrogen permeation tube, high-purity hydrogen can be directly produced from hydrocarbons and / or alcohols without providing a refining device. (2) The multi-burner, radiant plate, raw material supply pipe, reaction pipe, reforming catalyst layer, hydrogen permeation pipe, hydrogen extraction pipe, and case are efficiently arranged. Especially, the diameter of the reaction pipe is reduced and heat transfer is improved. However, the generated heat energy is effectively used, the energy saving process is realized, the hydrogen production capacity is improved, and the entire apparatus becomes compact. (3) A multi-burner is placed at the top to prevent the flame from coming into direct contact with the reaction tube and to form a uniform downward flow of combustion gas. The occurrence of excessive hot spots can be prevented. (4) Since the sweep gas flowing in the hydrogen permeation tube and the reformed gas flowing in the reforming catalyst layer are mass-transferred by countercurrent contact through the hydrogen permeation tube wall, It is possible to increase the recovery rate and increase the hydrogen concentration in the permeated gas. (5) The step of separating and purifying hydrogen after the reaction is omitted. (6) The chemical equilibrium is shifted by the hydrogen permeation tube, the reforming temperature (700 to 800 ° C.) is lowered by 150 to 200 ° C. from the conventional one, and the selection range of materials used for manufacturing the device is expanded,
The price is low and the durability of the device is improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a schematic configuration of a hydrogen production device of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is an enlarged view of a part of FIG. 1, showing a detailed structure inside the reaction tube.

FIG. 4 is a diagram showing the principle of a membrane reactor type hydrogen production apparatus proposed so far.

[Explanation of symbols]

 1 Case 1a Combustion exhaust gas discharge port 2 Multi-burner 2a Nozzle 2b Flame 3 Reaction tube 3a Process off gas discharge port 4 Manifold 5 Reforming catalyst 10 Raw material supply pipe 10a Raw material gas supply port 11 Hydrogen extraction pipe 11a Hydrogen discharge port 12 Hydrogen permeation pipe 12a Sweep gas supply port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Uchida 3-2-15-106 Azamino, Midori-ku, Yokohama, Kanagawa Prefecture (72) Kennosuke Kuroda 15-1 Tomihisacho, Shinjuku-ku, Tokyo Mitsubishi Heavy Industries Engineering Co., Ltd. In the center (72) Inventor Hiroshi Makihara 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Sanryoh Heavy Industries Ltd. Hiroshima Research Institute (72) Inventor Kazuto Kobayashi 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Hishi Heavy Industries Ltd. Hiroshima Research Center

Claims (1)

[Claims] 1. An apparatus for producing hydrogen from a hydrocarbon and / or alcohol by a steam reforming reaction,
An upright cylindrical closed case having a combustion exhaust gas discharge port at the bottom, a plurality of head closed cylindrical reaction tubes standing upright inside the case, and a burner provided above the reaction tube inside the case. An upright cylindrical raw material supply pipe having a manifold provided at the bottom of the case, the reaction tube having an upper end opening inside the reaction tube and a lower end communicating with a raw material supply port of the manifold, and the raw material supply An upright cylindrical hydrogen take-out tube that surrounds the outer peripheral side surface of the pipe and has an upper end that opens and a lower end that communicates with the hydrogen discharge port of the manifold; An upright cylindrical hydrogen permeation tube communicating with a sweep gas supply port is included, and a reforming catalyst is filled between the hydrogen permeation tube and the reaction tube.