JPH05155602A - Thin type steam reforming reactor - Google Patents

Abstract

PURPOSE:To provide a thin type steam reforming reactor for generating a gas contg. hydrogen by the reaction of hydrocarbons or alcohols with steam, appropriate as the fuel reformer for the fuel cell with hydrocarbons or alcohols as the fuel and capable of being set in a small area. CONSTITUTION:A plate-fin compartment is set alternately in multiple stages to constitute a reaction chamber 11 provided with a thin-film steam reforming catalyst 1 and a heating chamber 12 furnished with a combustion catalyst 2. The thickness of the catalyst 1 and combustion catalyst is preferably controlled to 0.2 to 2mm and the thickness of the reaction chamber 11 and heating chamber 12 to 0.7 to 4mm. The plate-fin compartments can be concentrically set in multiple stages to constitute the reactor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam reforming reactor capable of carrying out a reaction to obtain a gas containing hydrogen by reacting a hydrocarbon or alcohol with steam. The present invention relates to a thin steam reforming reactor having a small installation area and a small reactor volume, which can be preferably applied as a fuel reforming device for a fuel cell using fuel.

[0002]

2. Description of the Related Art Conventionally, a reactor for the purpose of carrying out a reaction to obtain a gas containing hydrogen by reacting hydrocarbons or alcohols with steam has a steam reforming catalyst in a heating furnace. Was an array of cylindrical reactors. The reactor having such a configuration has a large installation area and a large apparatus volume in spite of the small amount of hydrogen generated. Therefore, when assembling a small on-site type fuel cell package, it has been a big obstacle to downsizing the entire package.

In recent years, as means for overcoming this obstacle,
A steam reforming reaction apparatus has been proposed in which the interior of a double cylinder having a relatively large diameter is used as a combustion chamber, and the outer peripheral portion is filled with a steam reforming catalyst molded into pellets, and these problems have been improved to some extent. However, the problem was that a large combustion chamber remained in the center.

In order to improve this point, Japanese Unexamined Patent Publication (Kokai) No. 62-167203 proposes a reactor in which the combustion chamber has a rectangular shape and is alternately arranged with the steam reforming reaction chamber. However, even in this proposal, since the pellet-shaped catalyst is used in the steam reforming portion and the combustion portion, it cannot be said that the installation area and the apparatus volume are still sufficiently small.

The above-mentioned improved double-cylindrical reactor having a relatively large diameter, the reactor in which the combustion chamber has a rectangular shape and is alternately arranged with the steam reforming reaction chamber (hereinafter, these are collectively referred to as an improved reactor. In both cases, the size of the compartments forming the combustion chamber and the steam reforming reaction chamber is practically 2 in the width of one compartment.
About 0 to 60 mm is necessary, and the installation area and the apparatus volume of the improved reactor as a whole are still quite large. Therefore, further miniaturization is required.

[0006]

It is an object of the present invention to provide a steam reforming reactor for producing hydrogen by reacting hydrocarbons or alcohols with steam as described above so that the width of one compartment is larger than that of the improved reactor described above. It is an object of the present invention to propose a steam reforming reactor which can be made extremely thin, and therefore can be significantly reduced in both installation area and apparatus (reactor) volume as compared with these improved reactors.

[0007]

[Means for Achieving the Object] As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that the steam reforming catalyst and the combustion catalyst can be formed into a thin film shape. By using each of the catalysts, it is possible to make the steam reforming chamber and the combustion chamber (heating chamber) compartments thin and plate-shaped, and to make the installation area of the steam reactor and the reactor volume extremely small. The present invention has led to the proposal of the thin steam reforming reactor of the present invention.

That is, the thin steam reforming reactor of the present invention comprises plate-shaped compartments stacked in multiple layers.
Every other one is characterized by being configured as a heating chamber and a reaction chamber equipped with a steam reforming catalyst molded in a thin film shape. The plate-shaped compartments may be superposed in a concentric cylindrical shape, and the heating chamber may also be
A combustion catalyst molded into a thin film may be provided. The thickness of the steam reforming catalyst molded into the above thin film is 0.2 to 2 mm, and the thickness of the reaction chamber is 0.7 to 4 m.
m, the thickness of the combustion catalyst molded into a thin film is 0.2 to 2 mm
And the thickness of the heating chamber is 0.7 to 4 mm.

In the reactor of the present invention, the steam reforming catalyst formed into a thin film has Al ₂ O ₃ , ZrO ₂ or the like as a carrier, nickel or noble metal as the main active species, and La, Ba, Known catalyst components containing a third component such as Ce and Ca can be preferably used.

To mold these catalyst components into a thin film steam reforming catalyst, the following four methods are adopted. (1) Vacuum deposition method: A catalyst component is heated to a high temperature in a high vacuum to evaporate, the vapor is made to collide with a substrate (for example, stainless steel foil, etc., hereinafter the same), and then cooled and solidified to form a thin film. Make a state.

(2) Sputtering method: When the surface of a solid catalyst component is irradiated with an ion beam having a kinetic energy of several tens of eV or more, atoms existing in the vicinity of the surface of the component are kinetic energy of the ion beam. Are released into a vacuum and the atoms reach the surface of the substrate to form a film. An inert material such as Ar or Kr is used as the ion beam, and direct current bipolar sputtering, direct current bias sputtering, asymmetrical alternating current sputtering, getter sputtering, high frequency sputtering or the like is used as a sputtering method for generating the ion beam. It

(3) Chemical method: A desired thin film is formed by supplying a compound consisting of a catalyst component or a simple substance gas onto a substrate and performing a chemical reaction in the gas phase or on the surface of the substrate.

(4) Immersion coating method: First, the substrate is dipped in a solution of a carrier component of the above catalyst components to apply the carrier component solution, and this coating film is baked at a high temperature for a short time. This dip coating and baking operation is repeated to form a carrier component film having a desired thickness, and this film is baked at a temperature higher than the above and for a long time. Next, the active ingredient and the third ingredient of the above-mentioned catalyst ingredients are carried on the carrier ingredient film by the same dip coating method as in the case of the carrier ingredient, and baked at a high temperature for a long time.

As a method for holding the thin-film steam reforming catalyst molded as described above in the reaction chamber, for example, the methods shown in FIGS. 10A to 10C are adopted. According to the method of FIG.
0 and the thin film catalyst 101, a thin spacer (for example, a wire mesh) 102 that can secure a fluid flow is used. The thin spacer 102 is bent into a corrugated shape as shown in the drawing, and the thin film catalyst 101 is sandwiched between the two bent spacers 102. Then, install it in the reaction chamber. In the method of FIG. 1B, the side wall 100 of the reaction chamber is
The thin film catalyst 101 is held in the reaction chamber by carving a groove 103 serving as a fluid flow path on the surface and sandwiching the thin film catalyst 101 between the surfaces of the side walls 100 where there is no groove 103. In the method of FIG. 2C, a large number of protrusions 104 are provided on the surface of the side wall 100 of the reaction chamber, and the thin film catalyst 101 is held by the protrusions 104 to support the thin film catalyst 101.

The thickness of the thin film steam reforming catalyst is
If it is too thick, it becomes meaningless to make it into a thin film, and if it is too thin, the catalytic effect cannot be obtained.
It is preferably about 2 mm, most preferably about 1 to 0.2 mm. If the thickness of the reaction chamber (that is, the distance between the plates serving as the walls on both sides of the reaction chamber) is too thick, not only the miniaturization, which is one of the objects of the present invention, cannot be achieved, but also the thin film steam reforming catalyst. Depending on the manner of attachment of the reforming raw material to the reaction chamber, a situation may occur in which a part of the reforming raw material passing through the reaction chamber cannot contact the catalyst. On the contrary, if it is too thin, the reforming reaction rate decreases and the production Since there are inconveniences such as deterioration of the property, the thickness of the catalyst plus about 0.5 to 2 mm,
Specifically, it needs to be about 4 to 0.7 mm, and practically about 1 to 1.8 mm is preferable.

The reaction chamber equipped with the above-mentioned thin film steam reforming catalyst and the heating chamber are partitioned by a single partition wall (plates on both sides of the reaction chamber, the same applies hereinafter), It is preferable from the viewpoint of reaction efficiency and thermal efficiency that the flow of the raw material and the reaction product of the steam reforming reaction in the reaction chamber and the flow of the high temperature fluid in the heating chamber be countercurrent.

By the way, in the reactor of the present invention, the heat required for the steam reforming reaction is obtained by the high temperature fluid flowing in the heating chamber. As this high temperature fluid, it is also possible to use high temperature gas obtained by burning fuel in a separately provided combustion chamber,
It is also possible to use the combustion gas obtained by burning the fuel directly in the heating chamber. When the reactor of the present invention is used in combination with a fuel cell, a hydrogen residual gas discharged from the fuel cell may be introduced into a heating chamber and burned as a fuel to be used.

As described above, when the fuel is burned in the heating chamber, it is preferable to provide a combustion catalyst in the heating chamber. As the combustion catalyst, a known catalyst component in which a ceramic such as alumina, silicon carbide or silicon nitride is used as a carrier and a noble metal is supported can be used. Although these combustion catalysts may be used in the form of pellets as in the conventional case, it is preferable to use the ones in the form of thin film similar to the above steam reforming catalyst. Is preferable for further downsizing.

To form these into a thin-film combustion catalyst, the same method as the above-mentioned method for forming a thin-film steam reforming catalyst can be adopted, and the method of holding the thin-film combustion catalyst in the heating chamber is also the above. A method similar to the method of holding the thin film steam reforming catalyst described above in the reaction chamber is adopted. The thickness of the combustion catalyst formed into a thin film and the width of the heating chamber when the thin film catalyst is used are the same for the same reason as the thickness of the thin film steam reforming catalyst and the width of the reaction chamber. The thickness and width of

Further, in the reactor of the present invention, the reaction chamber and the heating chamber provided with the above-mentioned thin film steam reforming catalyst may be formed in a concentric cylindrical shape and superposed. At this time, the heating chamber may also be provided with a thin-film combustion catalyst.

In the reactor of the present invention, the reaction product gas taken out from the reaction chamber and the temperature-decreased gas or combustion exhaust gas discharged from the heating chamber are steam reforming raw material and combustion air, respectively, according to known methods. By exchanging heat with the fuel gas, it is possible to improve the thermal efficiency.

Further, the raw material for the steam reforming reaction which can be used in the reactor of the present invention is a C ₁ -C ₄ hydrocarbon,
Naphtha Kerosene hydrocarbons, C ₁ -C ₄ alcohols, C
Known raw materials such as alcohols of ₅ or more may be used. Furthermore, the conditions of the steam reforming reaction in the reactor of the present invention are generally a temperature of about 600 to 900 ° C. and a pressure of about 0.5 to 1.
5Kg / cm ² (absolute pressure), LHSV about 0.5-6h
^-1 , S (steam) / C (carbon) (molar ratio) is preferably about 2-5.

[0023]

The function of the steam reforming reaction itself is very fast, but the steam reforming reaction is a very large endothermic reaction, so that the substantial reaction rate is limited by the heat transfer rate. There is. So far, as a measure to improve the heat transfer area,
Attempts have also been made to improve the plate-type reaction tube,
That was not enough.

That is, a plate-type reaction tube was filled with a conventional pellet-shaped molded catalyst to form a reaction chamber, and the thickness of the reaction chamber was reduced to increase the heat transfer area per unit catalyst. However, due to the pressure loss of the reaction bed, the pellet size is limited to about 3 mm, and thus the thickness of the reaction chamber is limited to about 10 mm. Moreover, since the flow of the gas in the reaction chamber passes through the gap of the pellet catalyst, the flow in the boundary film portion of the wall of the reaction chamber becomes poor, which is an obstacle to heat transfer.

On the other hand, in the reactor of the present invention, the steam reforming catalyst formed into a thin film is used, and therefore the thickness of the reaction chamber (the space between the plates is smaller than that in the case where the conventional pellet catalyst is used). ) Can be made extremely small, and the problem of the heat transfer area can be solved. That is, since the thin film steam reforming catalyst is used, pressure loss does not occur, the plate interval can be narrowed, and the flow of the gas body in the boundary film part in the plate part becomes good, so that part No heat transfer resistance occurs. Moreover, the thin film steam reforming catalyst widens the heat transfer area of the catalyst itself.

As a result, in the reactor of the present invention, the heat transfer rate is improved, and the reaction can be carried out at a higher speed than in the case of using the conventional pelletized catalyst. As a result, the footprint and the reactor volume are reduced. It is significantly reduced as compared with the case of using the conventional pelletized catalyst.

For example, if the thicknesses of the steam reforming catalyst and the combustion catalyst formed into a thin film are finished to about 1 mm,
It is sufficient that the reaction chamber and the heating chamber each have a thickness of about 2 mm. Assuming that the vertical and horizontal dimensions of each of these chambers are about 600 mm, for a fuel cell of about 50 kW, the reaction chamber and heating chamber are about 87 m in internal dimension excluding the heat insulating material.
m. In the case of the conventional large-diameter double-cylinder system on this scale, the inner diameter is about 500 mm and the length is about 1000 mm
Therefore, in the reactor of the present invention, the volume of the conventional large-diameter double-cylindrical reactor (apparatus) is about 1/6 and the installation area is about 1/3. In the case where the plate-shaped compartments (that is, the reaction chamber and the heating chamber described above) are superposed in a concentric cylindrical shape to form the reactor of the present invention, it is for a fuel cell of about 50 kw and has a diameter of about 217 mm,
The height is about 900 mm, the volume of the conventional large-diameter double-cylindrical reactor (apparatus) is about 1/6 or more, and the installation area is about 1/5.

[0028]

EXAMPLE FIG. 1 is an external view for explaining the basic structure of a reactor of the present invention, and FIG. 2 is a sectional view of FIG.
The reactor of the present invention shown in FIG. 1 has a structure in which a reaction chamber 11 storing a catalyst and both sides thereof are sandwiched between heating chambers 12. The reaction chamber 11 and the heating chamber 12 of this reactor have a size of 45 mm × 40 mm × 2 mm, and inside the reaction chamber 11, as shown in FIG. Formed, the carrier is Al ₂ O
₃ << Production amount 0.8677g, thickness 250μ per side
m >>, the active metals are NiO 15 wt% and K ₂ O ₅ wt
%) (The total thickness including the thickness of the spacer is 1 mm) 1 is installed almost at the center. The catalyst 1 is installed in the reaction chamber 11 as shown in FIG.
According to a method like (C). In this example, FIG.
The method of (A) was adopted.

The reforming raw materials (hydrocarbons or alcohols and steam) introduced from the line 3 are supplied to both sides of the thin film steam reforming catalyst 1 inside the reaction chamber 11 to carry out the reaction. .. The gas after the reaction is taken out from the line 5.

The heat required for the above reaction is supplied from the heating chambers 12 installed on both sides of the reaction chamber 11 through the partition wall 7. That is, in this example, the hot gas is supplied to the line 10
Is introduced into the heating chamber 12 and the heat of the gas is supplied to the reaction chamber 11 through the partition wall 7. The cooled gas is discharged from the line 6. As described above, the flow of the reforming raw material in the reaction chamber 11 and the flow of the high temperature gas in the heating chamber 12 are countercurrent directions. Although not shown, a heat insulating material is applied to the outside of the heating chamber 12 (that is, the outside of the reactor of the present invention).

In the above embodiment, the reaction volume can be easily increased by adding the compartments for the heating chamber 12 and the reaction chamber 11.

Using the reactor of the present invention configured as described above, using sufficiently desulfurized kerosene (sulfur content 0.18 ppm) and steam as reforming raw materials introduced from line 3,
High temperature combustion gas (gas obtained by burning in another combustion facility) in the heating chamber 12 so as to keep the outlet temperature of the reaction chamber 11 (temperature of the reformed gas << hydrogen-containing gas >> taken out from the line 5) at 800 ° C. ) Was introduced through line 10 to carry out the reforming reaction. The results of this reaction are shown in Table 1.

For comparison, a conventional granular catalyst (A
l ₂ O ₃ << 0.8677g >> as a carrier, NiO15w
t% and K ₂ O ₅ wt% as active metals are used), and a kerosene (sulfur content 0.18 ppm) sufficiently desulfurized and steam are used as reforming raw materials by a cylindrical reactor filled with
Table 2 shows the results of carrying out the reforming reaction while keeping the outlet temperature of the reaction chamber at 800 ° C.

[0034]

[Table 1]

[0035]

[Table 2]

As is clear from Tables 1 and 2, the reactor of the present invention has a reaction material feed rate of 4.6 times that of the conventional reactor filled with the steam reforming catalyst in pellet form. Despite the fact that it functions in the same way, when a conventional reactor using a pellet-shaped steam reforming catalyst is increased to a reaction material feed rate similar to that of the reactor of the present invention, the reaction rate decreases. Was given. As a result, according to the reactor of the present invention, as compared with the reactor packed with the conventional pellet-shaped steam reforming catalyst,
It is proved that the size can be greatly reduced.

FIG. 3 (external view), FIG. 4 (cross-sectional view), FIG. 5 (cross-sectional view), and FIG. 6 (cross-sectional view) are views showing other embodiments of the reactor of the present invention. In the example, the heating chamber 1
2 also shows the case where a thin film combustion catalyst is installed inside.

In the example shown in FIG. 3, seven compartments are provided, and heating chambers 12 and reaction chambers 11 are alternately arranged. FIG. 4 is a sectional view of FIG. 3, in which a thin-film-shaped combustion catalyst 2 is installed in the center of the heating chamber 12, and eight fuel supply pipes 8 are horizontally arranged inside the heating chamber 12. As shown in FIG. 8, which is a sectional view taken along the line ab of FIG. 3, the fuel supply pipe 8 is provided with a large number of nozzle holes 9, and the nozzle holes 9 are used to introduce from the line 4. The fuel reaches the thin film combustion catalyst 2 sufficiently. In addition, as shown in FIG. 5, the fuel supply pipe as described above may not be arranged in the heating chamber 12. The exhaust gas in the heating chamber 12 is discharged from the line 6 in both cases of FIG. 4 and FIG. In addition, the heating chamber 12 and the reaction chamber 11
In both cases of FIG. 4 and FIG. 5, like the example shown in FIG. 1 and FIG.

When the reactor shown in FIGS. 4 to 5 is combined with a fuel cell, hydrogen residual gas discharged from the fuel cell can be used as fuel. The supply of the reforming raw material and the extraction of the reformed gas after the reforming reaction in the examples shown in FIGS. 4 to 5 are the same as those in the examples shown in FIGS.

FIG. 6 shows an example in which the installation position and the installation quantity of the thin film combustion catalyst 2 and the thin film steam reforming catalyst 1 installed in each of the heating chamber 12 and the reaction chamber 11 in FIG. 4 are changed. There is. That is, in the example of FIG. 6, a total of four combustion catalysts 2 molded in a thin film on each side of the partition wall 7 facing the inside of the heating chamber 12, inside the reaction chamber 11 of the partition wall 7. Two steam reforming catalysts 1 formed into a thin film are installed on each of the facing sides in total. Then, four fuel supply pipes 8 are arranged in the center of the heating chamber 12,
As in the case of FIG. 4, the fuel introduced from the line 4 shown in FIG. 8 is supplied to the combustion catalyst 2 from the supply pipe 8 and becomes hot gas at high temperature by catalytic combustion. In addition, as shown in FIG. 7, the fuel supply pipe as described above may not be arranged in the heating chamber 12.

Further, the thin film steam reforming catalyst 1 and the combustion catalyst 2 are installed on both left and right sides of the inner wall surfaces of the reaction chamber 11 and the combustion chamber 12 in the examples shown in FIGS. Of course, it may be installed only on one of the wall surfaces, but it is preferable to install it on both the left and right sides in terms of thermal balance. When the reactor shown in FIGS. 6 to 7 is combined with a fuel cell, the hydrogen residual gas discharged from the fuel cell can be used as a fuel as in the case of FIGS. 3 to 4. In addition, also in the example shown in FIGS. 6 to 7,
The supply of the reforming raw material and the extraction of the reformed gas after the reforming reaction are the same as in the example shown in FIGS.

FIG. 9 shows an embodiment in which the reactor of the present invention is constructed by stacking plate-like compartments in a concentric cylindrical shape in multiple layers. (A) is an external view,
(B) is a cross-sectional view taken along the line AB of (A), and (C) is an explanatory view showing a mounting mode of a pipe for introducing and taking out raw materials and the like. In this example, the plate constituting the side wall of the reaction chamber 11 and the plate constituting the side wall of the heating chamber 12 in which the thin film steam reforming catalyst 1 held by the mesh spacer of the embodiment shown in FIG. These plates are the reaction chamber 11
And the partition wall 7 of the heating chamber 12) are bent so as to have a cylindrical shape, and the plates of these cylindrical shapes are concentrically stacked to form the reactor of the present invention. The same reference numerals as those in FIGS. 1 and 2 denote the same functional units as those in FIGS. Although not shown in the drawings, the heating chamber 12 provided with the thin-film combustion catalyst 2 as shown in FIGS. 3 to 8 can be formed into a concentric cylindrical shape as shown in FIG. Needless to say.

[0043]

As described in detail above, according to the reactor of the present invention, the size of the reactor is significantly reduced as compared with the conventional steam reforming reactor using pellet-shaped steam reforming catalyst or combustion catalyst. And the reactor volume and installation area can be made extremely small. Therefore, it can be preferably applied as a fuel reformer for a fuel cell using hydrocarbons or alcohols as a fuel, and a small on-site fuel cell package can be easily put into practical use. Moreover, at this time, if a thin-film combustion catalyst is also provided in the heating chamber, the residual fuel hydrogen gas discharged from the fuel cell is introduced into the heating chamber and the heat obtained by burning it as fuel is converted to steam. It can also be supplied to the quality reaction, and the thermal efficiency can be improved.

[Brief description of drawings]

FIG. 1 is an external view for explaining an example of a reactor of the present invention.

FIG. 2 is a cross-sectional view of FIG.

FIG. 3 is an external view for explaining another embodiment of the reactor of the present invention.

4 is a cross-sectional view of FIG.

FIG. 5 is a diagram for explaining a modified example of FIG.

FIG. 6 is a diagram for explaining another modification example of FIG. 4;

FIG. 7 is a diagram for explaining another modification example of FIG. 6;

8 is a sectional view of the example of the combustion chamber shown in FIGS. 4 and 6 in the other direction, and is a sectional view taken along the line ab of FIG.

FIG. 9 is a view for explaining still another embodiment of the reactor of the present invention, (A) is an external view, (B) is an AB of (A).
A line cross-sectional view, (C) is an explanatory view showing a mounting mode of a pipe for introducing and taking out raw materials and the like.

FIG. 10 is a diagram showing an example of holding the thin film catalyst according to the present invention in a reaction chamber.

[Explanation of symbols]

 1 Thin-Film Steam Reforming Catalyst 2 Thin-Film Combustion Catalyst 3 Reforming Raw Material Introduction Line 4 Fuel Introduction Line 5 Gas Extraction Line After Reforming Reaction 6 Exhaust Gas Exhaust Line from Heating Chamber 7 Partition (Plate) 8 Fuel Supply Pipe 9 Nozzle hole 10 High temperature gas introduction line 11 Reaction chamber 12 Heating chamber

Claims (5)

[Claims] 1. A plurality of plate-shaped compartments, which are stacked in multiple layers, are arranged as a heating chamber and a reaction chamber provided with a steam reforming catalyst formed into a thin film. Thin steam reforming reactor. 2. The thin steam reforming reactor according to claim 1, wherein the plate-shaped compartments are superposed in a concentric cylindrical shape. 3. The thin steam reforming reactor according to claim 1, wherein the heating chamber is equipped with a combustion catalyst formed in a thin film shape. 4. The steam reforming catalyst formed into a thin film has a thickness of 0.2 to 2 mm, and a reaction chamber has a thickness of 0.7 to 4 m.
The thin steam reforming reactor according to any one of claims 1 to 3, wherein m is m. 5. The combustion catalyst formed into a thin film has a thickness of 0.
The thin steam reforming reactor according to claim 3, wherein the heating chamber has a thickness of 2 to 2 mm and a thickness of the heating chamber of 0.7 to 4 mm.