JPH06345405A - Hydrogen production device - Google Patents

Abstract

PURPOSE:To provide a hydrogen production device capable of producing high- purity hydrogen by carrying out each reaction in a modifier, a carbon monoxide transformer and a hydrogen purifier collectively. CONSTITUTION:A hydrogen production device is equipped with an upright cylindrical burner 1, a radiating plate 2 covering the burner, a hollow double wall closed reactor 3 arranged annularly at the outer periphery of the radiating plate, plural upright hydrogen permeating pipes 4 which are annularly arranged between the double wall of the reactor, have an outlet of a sweeping gas at the top and are closed at the bottom, a closed inner tank 5 which covers the outer wall and the bottom of the reactor at a fixed interval and has an inlet of a raw material gas and steam, a closed outer tank 6 which covers the inner tank, takes in an exhaust gas of combustion in the burner from the top of the radiating plate, brings the exhaust gas into contact with the inner wall and the bottom of the reactor, raises the exhaust gas along the outside of the inner tank and discharges and a sweeping gas pipe 9 which is coaxially inserted into the hydrogen permeating pipe and is equipped with an exhaust vent 9a of hydrogen and the sweeping gas. A modifying catalyst 7 is packed into the hollow part of the reactor.

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 for producing hydrogen in a reformer by utilizing a steam reforming reaction from hydrocarbons and / or alcohols is widely used industrially. 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 poisoned by CO, so the CO concentration in the hydrogen-containing gas supplied to the fuel cell must be 1% or lower. There is.
Fuel cells that operate at a relatively low temperature of 200 ° C. or less include phosphoric acid type that operates at 150 to 230 ° C., solid polymer membrane type that operates at 100 ° C. or less, and alkaline type, but especially at 100 ° C. or less. In the working solid polymer membrane type,
The CO concentration in the hydrogen-containing gas supplied to the fuel cell is 10 pp
It is said that it must be less than m. 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 in high purity has complicated steps, the entire apparatus is large, and a large amount of high-temperature heat energy is required.
In addition, the efficiency of the device is low, there is a drawback that the hydrogen production cost is inevitably high, and to produce high-purity hydrogen that is directly supplied from a city gas or the like to a solid polymer fuel cell,
It is extremely difficult considering the economic 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. No. 17401 and Japanese Patent Application No. 4-321502. However, in these prior applications, only the basic principle of the reactor is proposed, and a practical reactor configuration that can be easily increased in size, in particular, a heating system and a supply / discharge method 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 outside the inner tube. It has been shown that the outer tube wall is heated with an appropriate heat medium by filling the catalyst with a high-quality catalyst, and if this idea is expanded to consider the configuration of a large-scale practical machine, it will inevitably become a multi-tube reactor. The structure is complicated, has a large weight, and has a large heat capacity, and therefore problems such as poor startability / stopability and poor load followability occur.

The present invention has been made in view of the above points, and the reactions of the reformer, the carbon monoxide shift converter and the hydrogen purifier, which have been used in the conventional process, are collectively carried out to obtain a high purity. It is an object of the present invention to provide a so-called membrane reactor-type highly practical hydrogen production device capable of producing hydrogen.

[0006]

In order to solve the above problems, the present invention is an apparatus for producing hydrogen from hydrocarbons and / or alcohols by a steam reforming reaction, which encloses an upright cylindrical burner and the burner. A radiation plate, and a hollow double-walled closed reaction vessel which is annularly arranged on the outer periphery of the radiation plate at a constant distance from the radiation plate and has an offgas discharge port at the top and an open bottom. A plurality of upright hydrogen permeation tubes, which are annularly arranged in the hollow portion between the double walls of the reaction vessel and have a sweep gas inlet at the top and a closed bottom, and the outer wall and bottom of the reaction vessel are fixed. A closed inner tank having a bottom part connected to the inner wall of the reaction vessel and having an inlet for raw material gas and water vapor in the upper part of the combustion chamber surrounded by the inner wall of the burner. Intake exhaust gas from above the radiation plate And a closed outer tank which is brought into contact with the inner wall and the bottom surface of the reaction vessel so as to rise along the outer surface of the inner tank and discharge the hydrogen. And a sweep gas pipe provided with a sweep gas outlet and having a bottom opening near the bottom of the hydrogen permeation pipe, wherein a reforming catalyst is filled around the hydrogen permeation pipe in the hollow portion of the reaction vessel. To do.

[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 others), a heating burner, etc. Pure hydrogen can be produced. That is, high-purity hydrogen can be easily obtained by providing a hydrogen permeation tube in the catalyst layer of the reaction vessel, and heat can be efficiently transferred to the catalyst layer by providing a burner in the center and a radiation plate around the burner. Well, the combustion exhaust gas of the burner flows outside the inner tank in which the raw material gas flows, so that the raw material gas can be preheated, and the sweep gas becomes a counterflow to the gas flow in the catalyst layer, so that hydrogen is efficiently permeated. In addition, the chemical equilibrium is shifted by the hydrogen permeation tube, and the reforming temperature (700-800
C) is reduced 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.

An upright cylindrical burner 1 which burns fuel such as city gas or natural gas blown from a central hole of the bottom portion 8 constructed of an annular refractory material to generate high temperature flue gas is at the center of the hydrogen production apparatus. It is provided. The hydrogen production apparatus of FIG. 1 is shown with the manifolds and protective cover material attached to the outer periphery thereof removed.

A cylindrical radiant plate 2 is provided around the burner 1 at the outer periphery thereof, and the high temperature gas inside the burner 1 is directed outward from between the ceiling plate 1a of the burner 1 and the upper peripheral edge of the radiant plate 2. It is configured to be discharged to.

On the outer periphery of the radiation plate 2, a reaction vessel 3 having a double-wall structure composed of an inner wall 3a and an outer wall 3b is arranged with a constant gap from the radiation plate 2. The upper end of the outer wall 3b is covered with a ceiling plate 3e, the upper end of the inner wall 3a is connected to the ceiling plate 1a of the burner 1, and the entire reaction vessel 3 is airtight. Further, the reaction container 3 has an offgas discharge port 3c at the top and an opening at the bottom 3d. The off-gas is the generated gas obtained by permeating and removing hydrogen.

A plurality (eight in FIG. 2) of hydrogen permeation pipes 4 are annularly arranged upright at substantially equal intervals in the hollow portion between the inner wall 3a and the outer wall 3b of the double-wall structure of the reaction vessel 3. ing. Further, the upper end of the hydrogen permeation tube 4 projects upward from the ceiling plate 3e of the reaction vessel 3. The hydrogen permeation tube 4 has a sweep gas inlet 4a at the top and a closed bottom 4c at the bottom. The sweep gas is a gas for scavenging hydrogen generated in the hydrogen permeation tube 4.

A reforming catalyst 7 is filled around the hydrogen permeation pipe 4 in the hollow portion between the inner wall 3a and the outer wall 3b of the reaction vessel 3.

A sweep gas pipe 9 is inserted into the hydrogen permeation pipe 4 coaxially therewith. The sweep gas pipe 9 is provided with a hydrogen and sweep gas discharge port 9a at the top and has a bottom opening near the bottom of the hydrogen permeation pipe.

The inner tank 5 is provided so as to surround the outer wall 3b and the opening bottom portion 3d of the reaction vessel 3 in a gas-tight manner with a constant gap. The inner tank 5 has an inlet 5a for raw material gas and water vapor in the upper part, and is provided with a bottom portion 5b connected to the inner wall 3a of the reaction vessel 3 and an outer wall. The outer tank 6 encloses the outer wall of the inner tank 5 and the bottom portion 5b in an airtight manner, and is provided as the outermost part of the hydrogen production apparatus. The bottom wall 6b of the outer tank 6 is connected to the outer wall of the burner 1. The outer tank 6 takes in the high-temperature combustion exhaust gas in the burner 1 from the upper part of the radiation plate 2 and receives the inner wall 3 a of the reaction vessel 3.
And the bottom portion 5b of the inner tank 5 to flow,
It is configured to rise along the outer wall of the above and to be discharged from the combustion exhaust gas discharge port 6a provided at the upper end.

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

By burning the fuel in the burner 1, high temperature combustion exhaust gas is generated. The combustion exhaust gas flows in the direction of arrow C from between the ceiling plate 1a of the burner 1 and the upper peripheral edge of the radiant plate 2 into the annular gap between the radiant plate 2 and the inner wall 3a of the reaction vessel 3 and follows the inner wall 3a. At this time, heat is efficiently and evenly transferred to the reforming catalyst 7 in the reaction vessel 3 by the radiant plate 2, and further the space between the inner tank 5 and the outer tank 6 is raised to reach the outer tank 6. It is discharged from the combustion exhaust gas discharge port 6a to the outside. At this time, the inside of the inner tank 5 is efficiently heated, the raw material gas and steam being descended are preheated, and the reforming catalyst 7 inside thereof is also heated.

Raw material gas and water vapor flow into the inner tank 5 from the inlet 5a in the direction of arrow A, and sweep gas flows into the hydrogen permeation pipe 4 from the inlet 4a in the direction of arrow B.

While the raw material gas and water vapor enter the opening bottom portion 4c of the reaction vessel 3 from the bottom portion of the inner tank 5 and rise in the reforming catalyst 7 of the reaction vessel 3, carbonization is performed by heat generated by combustion of the fuel gas. Hydrogen is produced by steam reforming hydrogen. The reaction formula at this time is as follows, when an example of methane is shown. This hydrogen permeates into the hydrogen permeation pipe 4, and from there, through the sweep gas pipe 9 by the sweep gas, the discharge port 9a.
Is pushed out in the direction of arrow D from. Further, the off gas such as carbon dioxide gas in the reaction container 3 is discharged to the outside from the discharge port 3c in the direction of arrow E. At this time, the discharge flow direction of the off gas in the reforming catalyst 7 is the opposite direction to the inflow direction of the sweep gas in the hydrogen permeation pipe 4. As a result, hydrogen in the reforming catalyst 7 can be efficiently permeated into the hydrogen permeation pipe 4.

The apparatus of the above embodiment is inverted so that the burner is blown with fuel from above to burn, and sweep gas, raw material gas, and steam are introduced from the lower part, and hydrogen and off-gas are discharged from the lower part. You can also

Hydrogen permeation tube 4 which can be used in the apparatus having the above construction
As the film, a film that selectively permeates hydrogen and has heat resistance is used. For example, Pd with a film thickness of 100 μm or more
Alloy film or porous material containing P with a thickness of 50 μm or less
The thing coated with the thin film containing d is used. A film containing Pd contains 100% Pd or 10 Pd.
Alloys containing Pd, Ph, Ru, I other than Pd are alloys containing Pd of 10 wt% or more.
It refers to an element containing a Group VIII element such as r and an Ib group element such as Cu, Ag, and Au. In addition to the above films, alloy films containing V (vanadium), such as Ni-Co-V alloys with P
A film coated with d or the like is used. A ceramic porous body or a metal porous body is used as the porous body. As a method of coating a thin film containing Pd or V on these porous bodies, a liquid phase method such as plating, a vacuum deposition method, an ion plating method, a vapor phase method such as a vapor phase chemical reaction method (CVD), an alloy, etc. A method of attaching foil is used.

Further, as a catalyst, a Group VIII metal (Fe,
A catalyst containing Co, Ni, Ru, Rh, Pd, Pt, etc.) is preferable, and a catalyst supporting Ni, Ru, Rh or a NiO-containing catalyst is particularly preferable.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below. (1) Equipment dimensions and materials ・ Hydrogen permeation tube 4: Inner diameter 16 mm × Effective length 600 mm ・ Reaction vessel 3: Inner wall 3a: Inner diameter 180 mm × Catalyst filling height 620 mm Outer wall 3b: Inner diameter 250 mm × Effective length 600 mm ・ Outermost wall of inner layer 5: Inner diameter 256 mm x effective length 600 mm ・ Material: Austenitic stainless steel is adopted. (2) Hydrogen permeation tube As a strength supporting member, the same material with a thin wire diameter is used on the multilayer pressure sintered body of stainless steel wire mesh. A porous tube was formed by bending a plate material in which a nonwoven fabric made of metal fibers was diffusion-bonded into a cylindrical shape, and then welding the joint portion.

Further, a palladium thin film was formed on the outer surface of the porous tube by electroless plating. (3) Reforming catalyst As a steam reforming catalyst such as methane, a catalyst containing Ni and having an average particle diameter of 1 mm was filled between the inner wall 3a and the outer wall 3b of the reaction vessel 3 described above. (4) Fuel gas As the fuel gas, the remaining portion of the city gas and the reformed gas that did not pass through the hydrogen permeation tube, that is, the process off gas was used. (5) State on combustion side-City gas (flow rate): 11.7 mol / h (supply temperature): 25 ° C-Process off gas (flow rate): 97.8 mol / h (supply temperature): 550 ° C (composition) : H ₂ 8.4%, CO 6.3%, CO
₂ 55%, CH ₄ 7.5%, balance H ₂ O ・ Combustion air (flow rate): 326 mol / h (supply temperature): 420 ° C. ・ Combustion pressure: 1.05 kg / cm ² (6) Process gas side State ・ Mixed gas (flow rate) of raw material gas (city gas) and steam: 194 mol / h Of which, city gas is 57.0 mol / h (composition): CH ₄ 26.0%, C ₂ H ₆ 1.35 %, C
_{3 H 8 1.59%, n-} C 4 H 10 0.44% the balance H ₂ O · reforming temperature (inlet → outlet): 500 → 550 ℃ · reforming pressure (inlet → exit): 6.03 → 5.98k
g / cm ²・ Reformed gas (composition of outlet): Same as the composition of process off-gas of (5) (7) State of hydrogen permeation downstream ・ Sweep gas (using steam) at inlet (flow rate): 140 mol / H (temperature): 500 ° C. (pressure): 1.21 kg / cm ² (composition): H ₂ O 100% ・ Sweep gas (mixed gas of water vapor and permeated hydrogen) at the outlet (flow rate): 358 mol / h (Temperature): 550 ° C. (Pressure): 1.13 kg / cm ² (Composition): H ₂ 61.0%, balance H ₂ O As described above, using the apparatus of the present invention shown in FIGS. 1 and 2. , City gas was steam-reformed to produce hydrogen, and the hydrogen could be selectively permeated through a hydrogen permeation tube, entrained in steam as a sweep gas, and taken out to the outside. That is, 57.0 mol / h of city gas was sent as a raw material gas, and permeated hydrogen was 358 × 0.61 = 218.
This means that 4 mol / h was obtained. Incidentally, the permeated hydrogen is entrained in the water vapor, but since the water vapor is inactive to the catalyst of the fuel cell, there is no particular problem, rather,
In a polymer electrolyte fuel cell that requires humidification, it is a component that is easily mixed, and carbon monoxide, which is a catalyst poisoning component, is below the detection limit of the analytical sensor (1 ppm or less).

[0027]

As described above, according to the present invention, the following excellent effects can be obtained. (1) High-purity hydrogen can be directly produced from hydrocarbons and / or alcohols. (2) Burner, radiant plate, reforming catalyst layer, hydrogen permeation pipe, sweep gas pipe, inner tank, outer tank are efficiently arranged, heat transfer is improved, generated heat energy is effectively used, energy saving process Will be realized, the hydrogen production capacity will be improved, and the entire system will be compact. That is, the structure is greatly simplified as compared with the multi-tube reformer. (3) Since it is lighter than the multi-tube type, it has a small heat capacity and good responsiveness at the time of start / stop and load change. (4) Since the furnace is provided in the central portion, the heat transfer rate in the radial direction due to radiation is increased, and the heat flux distribution is easily made uniform. Therefore, it is possible to prevent the occurrence of hot spots that exceed the heat resistant temperatures of the hydrogen permeation tube and the reforming catalyst. (5) Exhaust heat is recovered by exchanging heat between the combustion exhaust gas and the process feed gas in a counterflow. There is no need to install a separate heat exchanger for this purpose. (6) Since the sweep gas flowing in the hydrogen permeation pipe and the reformed gas flowing in the reforming catalyst layer are mass-transferred by countercurrent contact via the hydrogen permeation pipe wall, It is possible to increase the recovery rate and increase the hydrogen concentration in the permeated gas. (7) The separation and purification steps after the reaction are omitted. (8) The hydrogen permeation tube shifts the chemical equilibrium, lowers the reforming temperature by 150 to 200 ° C, expands the selection range of materials used for manufacturing the device, lowers the price, and improves the durability of the device. Let

[Brief description of drawings]

FIG. 1 is a vertical 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 a principle diagram of a conventional membrane reactor type hydrogen production apparatus.

[Explanation of symbols]

 1 burner 1a, 3e ceiling plate 2 radiation plate 3 reaction vessel 3a inner wall 3b outer wall 3c off-gas discharge port 3d opening bottom 4 hydrogen permeation pipe 4a, 5a inlet 4c, 5b bottom 5 inner tank 6 outer tank 6a discharge port 6b bottom wall 7 Reforming catalyst 8 Burner tile 9 Sweep gas pipe 9a Sweep gas outlet

 ─────────────────────────────────────────────────── ─── 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 burner, a radiant plate surrounding the burner, and a hollow with an off gas discharge port on the upper part and an open bottom part that is annularly arranged on the outer periphery of the radiant plate with a certain distance from the radiant plate. A double-walled closed reaction vessel, and a plurality of upright hydrogen permeation tubes annularly arranged in the hollow space between the double walls of the reaction vessel and having a sweep gas inlet at the top and a closed bottom. And a closed inner tank having an outer wall and a bottom portion of the reaction vessel which are surrounded by a constant gap and which has an inlet for raw material gas and water vapor in the upper portion and which has a bottom portion connected to the inner wall of the reaction vessel, A hermetically sealed outside which surrounds the inner tank and takes in the combustion gas in the burner from the upper part of the radiant plate so as to contact the inner wall and the bottom surface of the reaction vessel and raise and discharge along the outer surface of the inner tank. And a tank, which is coaxially inserted into the hydrogen permeation tube. A sweep gas pipe having an outlet for hydrogen and a sweep gas and having a bottom opening near the bottom of the hydrogen permeation pipe is provided, and the reforming catalyst is filled around the hydrogen permeation pipe in the hollow portion of the reaction vessel. Characteristic hydrogen production equipment.