JP2007204343A - Reformer and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To convert a shift catalyst layer in an autooxidation internal heating type reformer into a metal honeycomb structure. <P>SOLUTION: In the autooxidation internal heating type reformer having a mixed catalyst layer 5 wherein a reforming catalyst and an oxidation catalyst are mixed, a shift catalyst layer 6 and a supply pipe 14 for supplying an oxygen-containing gas for oxidation to the mixed catalyst layer 5 and forming a hydrogen-rich reformed gas by steam-reforming a raw material-steam mixture, the supply pipe 14 is provided while passing through the center of a spiral shape of a spiral metal honeycomb structure 20 and extending to the mixed catalyst layer 5 and the shift catalyst layer 6 is formed by carrying the shift catalyst on the spiral part of the metal honeycomb structure 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a self-oxidation internal heating type reformer that generates a hydrogen-rich reformed gas by steam reforming a raw material gas, and a manufacturing method thereof, and more particularly, to a self-oxidation internal heating type in which a shift catalyst layer is made into a metal honeycomb. The present invention relates to a reformer and a manufacturing method thereof.

2. Description of the Related Art Conventionally, there is known a reformer that generates a hydrogen-rich reformed gas by steam reforming a mixture of a source gas and steam (hereinafter referred to as a source-steam mixture) in the presence of a reforming catalyst. The hydrogen-rich reformed gas obtained in the reformer is converted to CO ₂ by reacting residual CO (carbon monoxide) with an oxygen-containing gas in the presence of a catalyst by means of CO reduction, and operates at a particularly low temperature. For solid polymer electrolyte fuel cells, CO is reduced to several ppm level before being supplied as fuel. As the source gas, hydrocarbons such as methane, aliphatic alcohols such as methanol, ethers such as dimethyl ether, city gas, and the like are used. In such a reformer, the reaction formula of steam reforming when methane is used as a raw material gas can be expressed as CH ₄ + 2H ₂ O → CO ₂ + 4H ₂ , and a preferable reforming reaction temperature is 650 to The range is 750 ° C.

  There are an external heating type and an internal heating type as a system for supplying heat necessary for the reforming reaction of the reformer. The external heating type reformer is provided with a heating unit outside, and a reformed gas is generated by reacting a raw material gas and water vapor with a heat source. The internal heating type reformer is provided with a partial oxidation reaction layer on the supply side (upstream side), and the steam reforming reaction layer disposed on the downstream side using the heat generated in the partial oxidation reaction layer is subjected to a steam reforming reaction. Heating to a temperature is performed, and a steam reforming reaction is performed in the heated steam reforming catalyst layer to generate a hydrogen-rich reformed gas.

The partial oxidation reaction can be represented by CH ₄ + 1/2 · O ₂ → CO + 2H ₂ , and the preferable partial oxidation reaction temperature is in the range of 250 ° C. or higher. For example, Patent Documents 1 and 2 describe a self-oxidation internal heating type reformer as an improvement of the internal heating type reformer. The reformers of Patent Documents 1 and 2 have a double structure including an outer preliminary reforming chamber and an inner main reforming chamber. The main reforming chamber is provided with a catalyst layer and a discharge unit, the main reforming chamber receives a discharge from the discharge unit, a supply pipe for oxidized air, a mixed catalyst layer in which the reforming catalyst and the oxidation catalyst are mixed, a shift catalyst layer, and A reformed gas discharge unit is provided.

  FIG. 5B is a schematic cross-sectional view of a self-oxidation internal heating type reformer, and FIG. 5A is a cross-sectional view taken along line BB of FIG. 5B. The reformer 1 includes an outer preliminary reforming chamber 2 and an inner main reforming chamber 3 which are arranged in a double manner, and the entire reformer 1 is formed thin. Each of the preliminary reforming chamber 2 and the main reforming chamber 3 is elongated and has a flat cross section (in the illustrated example, a flat square shape), and the cross sections thereof are similar to each other. The preliminary reforming chamber 2 is formed between the outer cylinder 2a and the inner cylinder 3a, and the main reforming chamber 3 is formed inside the inner cylinder 3a. A reforming catalyst layer 4 is provided in the pre-reforming chamber 2, and a mixed catalyst layer 5 in which a reforming catalyst and an oxidation catalyst are mixed and a shift catalyst layer 6 are provided in the main reforming chamber 3 apart from each other in the vertical direction. The catalyst layer 6 includes a high temperature shift catalyst layer 7 and a low temperature shift catalyst layer 8.

Reforming catalyst are those of the raw material gas to steam reforming, for example, _NiO-A1 2 _{O 3} or Ni-based reforming catalyst such as _{NiO-SiO 2 · A1 2 O} 3 and _{WO 2} -SiO 2 · _A1 2 O ₃ and NiO-WO ₂ · SiO ₂ · A1 ₂ O ₃ are used. The reforming catalyst constituting the mixed catalyst layer 5 is the same as described above, and the oxidation catalyst uniformly dispersed therein is the temperature required for the steam reforming reaction by oxidizing the raw material gas in the raw material-steam mixture. For example, platinum (Pt), rhodium (Rh), ruthenium (Ru), or palladium (Pd) is used. The mixing ratio of the oxidation catalyst to the reforming catalyst is selected in the range of about 1 to 15% according to the type of the raw material gas to be steam reformed. For example, when methane is used as the raw material gas, it is about 5% ± 2%. In the case of methanol, the mixing ratio is about 2% ± 1%. Such mixed catalyst

  A raw material-steam mixture supply unit 9 is provided at the lower part of the preliminary reforming chamber 2, and a discharge unit 10 for discharging the effluent after the preliminary reforming is provided at the upper part of the preliminary reforming chamber 2. A supply unit 11 communicating with the discharge unit 10 of the preliminary reforming chamber 2 is provided at the upper part of the main reforming chamber 3, and a supply pipe 14 for supplying oxidized air to the central portion of the main reforming chamber 3 is extended. An air ejection portion 17 composed of a plurality of nozzles is formed at a portion where the supply pipe 14 extends to the mixed catalyst layer 5. Further, a reformed gas discharge section 12 is provided at the lower portion of the main reforming chamber 3.

  The main reforming chamber 3 is provided with a mixed catalyst layer 5, a high temperature shift catalyst layer 7 and a low temperature shift catalyst layer 8 in order from the top to the bottom, and the low temperature shift catalyst layer 8 including the boundary portion of each catalyst layer and the discharge portion 12. A support plate 15 for supporting the catalyst particles is disposed on the lower side (a similar support plate 15 is also disposed in the preliminary reforming chamber 2). These support plates 15 have a hole diameter that allows gas flow but does not allow catalyst particles to pass therethrough, and usually a porous member such as a plate-like punch metal or mesh is used.

  The discharge unit 12 includes a manifold provided in a space below the support plate 15 and an outlet tank connected to an end portion of the manifold extending outside the reformer 1. Then, the reformed gas that has flowed out to the discharge unit 12 passes through the support plate 15 and enters the manifold, and is discharged from there through the outlet tank.

  Next, the operation of the reformer 1 of FIG. 5 will be schematically described. The raw material-steam mixture supplied from the supply unit 9 is partly reformed by the action of the reforming catalyst 4 in the preliminary reforming chamber 2 to generate a hydrogen-rich reformed gas. The quality gas and the remaining raw material-steam mixture flow from the discharge unit 10 to the supply unit 11 of the main reforming chamber 3.

  The raw material-steam mixture flowing into the main reforming chamber 3 reacts with the oxygen in the air (oxidation reaction) due to the action of the oxidation catalyst contained in the mixed catalyst layer 5, and the raw material gas is generated by the oxidation heat. Reacts with water vapor (reforming reaction) to generate a reformed gas. The generated reformed gas converts CO (carbon monoxide) remaining in the high temperature shift catalyst layer 7 into hydrogen, and then further converts the remaining CO into hydrogen in the low temperature shift catalyst layer 8 to be discharged from the discharge unit 12 to the outside. Is done.

  In general, the catalyst of the reformer is often supported on a carrier to form a catalyst layer. Although some carriers are in the form of particles, the use of a honeycomb structure for the carrier has advantages such as ease of catalyst loading and excellent uniformity of gas flow. Since the reformer is operated at a high temperature, a metal honeycomb structure in which the material of the honeycomb structure is made of metal is used. The use of such a metal honeycomb structure as a catalyst carrier for a reformer is described in Patent Document 3, for example. Further, Patent Document 4 describes a metal honeycomb structure used as a catalyst carrier of an automobile exhaust gas purifier. Patent Document 4 shows a metal honeycomb structure having two or three spiral centers.

JP 2001-192201 A JP-A-2005-149860 JP 2004-269332 A JP-A-9-29106

  However, no catalyst carrier using a metal honeycomb structure is known as a catalyst carrier used in the above-described self-oxidation internal heating type reformer. In particular, when a metal honeycomb structure is employed as a catalyst carrier of a shift catalyst layer through which a supply pipe for supplying an oxygen-containing gas to the mixed catalyst layer passes, a part of the metal honeycomb structure must be cut and not penetrated through the supply pipe Therefore, it is easy to generate a gas through-pass path, and there is a risk of impairing the ease of filling the catalyst and the uniformity of ventilation, which are advantages of the honeycomb structure.

  Accordingly, the present invention aims to improve the catalyst carrier system in such a conventional self-oxidation internal heating type reformer, and provides a reformer using a metal honeycomb structure and a method for manufacturing the reformer. For the purpose.

The reformer of the present invention that solves the above problems includes a mixed catalyst layer 5 in which a reforming catalyst and an oxidation catalyst are mixed, a shift catalyst layer 6, and a supply for supplying an oxygen-containing gas for oxidation to the mixed catalyst layer 5 A self-oxidation internal heating type reformer having a pipe 14 and generating a hydrogen-rich reformed gas by steam reforming a raw material-steam mixture;
The shift catalyst layer 6 is formed by supporting a shift catalyst on the metal honeycomb structure 20,
The metal honeycomb structure 20 is formed in a spiral shape with a composite plate in which a flat strip made of a thin strip metal plate and a corrugated strip bent in a corrugated shape are overlapped, leaving a tubular space at the center. And
The reformer characterized in that the tubular space constitutes the supply pipe 14, and the supply pipe 14 extends through the spiral center of the spiral metal honeycomb structure 20 to the mixed catalyst layer 5. (Claim 1).
In the above configuration, one or more spiral centers of the metal honeycomb structure 20 may be present, and the supply pipe 14 may be penetrated for each spiral center (Claim 2).

Furthermore, in any one of the configurations described above, the metal honeycomb structure 20 can be formed in a spiral shape on the outer periphery of the composite plate by disposing the supply pipe 14 at one end edge of the composite plate. 3).
In the above configuration,
The mixed catalyst layer 5 can be formed from a mixture of a granular reforming catalyst and an oxidation catalyst, respectively.
Further, in the above configuration, an inner cylinder is formed on the outer periphery of the metal honeycomb structure 20, one end of the inner cylinder extends in the axial direction from the metal honeycomb structure 20, and the mixed catalyst layer is formed in the extended portion. 5 can be provided (claim 5).

Next, the present invention according to claim 6 is a mixed catalyst layer 5 in which a reforming catalyst and an oxidation catalyst are mixed, a shift catalyst layer 6, and a supply pipe 14 for supplying an oxygen-containing gas for oxidation to the mixed catalyst layer 5. In a method for producing a self-oxidation internally heated reformer that steam-reforms a raw material-steam mixture to produce a hydrogen-rich reformed gas,
A metal honeycomb structure 20 is formed by spirally winding a composite plate in which a flat strip made of a thin strip metal plate and a corrugated strip bent into a corrugated shape are wound around the supply pipe 14. At the same time, the shift catalyst layer 6 is formed by supporting the shift catalyst in the spiral portion.

  In the reformer of the present invention, the supply pipe extends through the spiral center of the spiral metal honeycomb structure to the mixed catalyst layer, and the shift catalyst is supported on the spiral portion of the metal honeycomb structure. Forming a layer. Therefore, since the metal honeycomb structure does not have a cut portion that penetrates the supply pipe, a reformer that can fully exhibit the ease of carrying the catalyst and the uniformity of ventilation that the metal honeycomb structure originally has is provided. Can do.

In the above reformer, when the metal honeycomb structure has one spiral center, the supply pipe can be penetrated through the spiral center, which is suitable, for example, when it is desired to increase the load of the shift catalyst. Further, when there are two or more spiral centers of the metal honeycomb structure, the supply pipe can be penetrated for each spiral center. For example, when it is desired to increase the supply amount of the oxygen-containing gas, or the mixed catalyst layer contains oxygen. This is suitable for the case where it is desired to supply gas more uniformly.
In the above reformer, when the supply pipe 14 is arranged at one end edge of the composite plate of the flat strip and the corrugated strip, and the composite plate is formed in a spiral shape on the outer periphery of the supply tube 14, The supply pipe 14 and the honeycomb structure can be easily manufactured.
In the above reformer, when the reforming catalyst and the oxidation catalyst of the mixed catalyst layer are each formed in a granular form, oxygen can be evenly and easily supplied to them from the supply pipe 14.
In the above reformer, when the inner cylinder 3a is disposed on the outer periphery of the metal honeycomb structure 20, the inner cylinder is extended in the axial direction from the metal honeycomb structure 20, and the mixed catalyst layer 5 is provided in the extended portion. Obtains a reformer with a small number of parts and a simple structure.

  In the reformer manufacturing method of the present invention, the metal honeycomb structure is disposed around the supply pipe in a spiral shape, and the shift catalyst layer is formed by filling the spiral portion with the shift catalyst. Features. Therefore, the formation of the metal honeycomb structure and the penetration of the supply pipe can be performed at a time, so that the production efficiency is high. Further, since the peripheral surface of the supply pipe is automatically brought into close contact with the inner wall of the spiral center of the metal honeycomb structure, there is no possibility that a gas through-pass path is formed in the through portion of the supply pipe.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1B is a schematic cross-sectional view of a supply pipe portion in the reformer of the present invention, and FIG. 1A is a cross-sectional view taken along line AA of FIG. The reformer 1 of the present embodiment is the same in principle as the reformer 1 of FIGS. 5 (A) and 5 (B). Therefore, the same parts are denoted by the same reference numerals, and redundant description is omitted as much as possible.

  The reformer 1 to which the present invention can be applied is not limited to such a double structure, but the pre-reforming chamber 2 and the main reforming chamber 3 are configured as separate bodies, or the pre-reforming. The present invention can also be applied to a configuration in which steam reforming is performed only in the main reforming chamber 3 without the chamber 2. Therefore, the “main reforming chamber 3” in which the supply pipe 14 in the present invention is disposed is the main reformer disposed separately from the main reforming chamber 3 disposed inside the double structure as shown in FIG. It means that the main reforming chamber 3 (single reforming chamber) without the quality chamber 3 or the preliminary reforming chamber 2 is included.

  The preliminary reforming chamber 2 and the main reforming chamber 3 are each formed in an elongated cylindrical shape, and the preliminary reforming chamber 2 is disposed outside and the main reforming chamber 3 is disposed inside. The pre-reforming chamber 2 is provided with a reforming catalyst layer 4, and the main reforming chamber 3 has a mixed catalyst layer 5 in which a reforming catalyst and an oxidation catalyst are mixed in the axial direction, a high temperature shift catalyst layer 7, and a low temperature shift catalyst layer. 8 are provided in order. The high temperature shift catalyst layer 7 and the low temperature shift catalyst layer 8 constitute a shift catalyst layer 6.

  The reforming catalyst layer 4 and the mixed catalyst layer 5 are configured, for example, by supporting a catalyst on a particulate ceramic support as in the conventional case, and the shift catalyst layer 6 supports a shift catalyst on a support of a spiral metal honeycomb structure. Configured. In the present embodiment, a metal honeycomb structure 20 having one spiral center at the center is used, and a straight tubular supply pipe penetrates the spiral center in the vertical direction as shown in the figure, and its tip is a mixed catalyst. Extends to layer 5.

  Note that an oxygen-containing gas (usually pressurized air) supplied from the outside through the supply pipe 14 is jetted into the mixed catalyst layer 5 from an air jet part 17 provided at the tip of the supply pipe 14. When the oxygen-containing gas is supplied to the mixed catalyst layer 5, a part of the raw material gas supplied from the raw material-steam mixture supply unit 9 is efficiently oxidized in the presence of the oxidation catalyst, and the mixed heat is generated by the generated oxidation heat. The catalyst layer 5 is maintained at a reforming temperature of about 700 ° C.

  FIG. 2 is an enlarged cross-sectional view of the metal honeycomb structure portion in FIG. The metal honeycomb structure 20 is disposed in close contact with the inside of the inner cylinder 3a, and a flat strip 21 made of a thin metal plate having heat resistance such as a thin steel plate or a thin stainless steel plate, and a wave obtained by corrugating the flat strip. A composite plate is formed by superimposing the plate-like strips 22, and the composite plate is tightly wound around a straight tubular supply pipe 14 in a spiral shape. Then, a shift catalyst is attached to each surface of the flat plate-like band 21 and the corrugated plate-like band 22 in the spiral portion, and the gap (space part) between the flat plate-like band 21 and the corrugated plate-like band 22 is the mixed catalyst layer 5. A reformed gas flow section flowing out from the tank is formed.

  In order to manufacture the metal honeycomb structure 20 of FIG. 2, first, the straight tubular supply pipe 14 is used as the winding center axis, and one end edge of the laminated body of the plate-like band body 21 and the corrugated-band-like band body 22 is formed around it. Position them and wind them in a spiral. After the laminate is wound to a predetermined diameter, the wound product is inserted into the inner cylinder 3a to complete the metal honeycomb structure 20 with the supply pipe 14 penetrating vertically as shown in FIG. To do. As shown in FIG. 1, the inner cylinder 3 a extends longer than the axial length of the metal honeycomb structure 20, and the mixed catalyst layer 5 is disposed in the extending portion.

  FIG. 3 is an enlarged cross-sectional view showing another example of the honeycomb structure portion of FIG. This embodiment uses a metal honeycomb structure (commonly called S-type) in which two spiral centers exist in the vicinity of the center, and straight tube-like supply pipes penetrate through the respective spiral centers as shown in the figure. The leading end of the supply pipe extends to the mixed catalyst layer 5. The manufacturing method of the honeycomb structure 20 is a composite plate made of a laminate of a plate-like band body 21 and a corrugated band-like body 22 around each of the two straight tubular supply pipes 14 as each winding center axis. An end edge can be arrange | positioned and it winds around a pair of supply pipe | tube 14, and can form it.

  FIG. 3 is an enlarged cross-sectional view showing still another example of the honeycomb structure portion of FIG. This embodiment uses a metal honeycomb structure (commonly called SM type or saddle type) having three spiral centers near the center, and a straight tubular supply pipe passes through each spiral center as shown in the figure. The tips of the supply pipes extend to the mixed catalyst layer 5. In the method for manufacturing the honeycomb structure 20, the end portions of the composite plate composed of a laminate of the plate-like band body 21 and the corrugated plate-like band body 22 are arranged on three straight tubular supply pipes 14 to supply them. The tubes are brought close to each other, and each composite plate is wound around them in a spiral shape.

  The reformer of the present invention can be used for a reformer that generates a hydrogen-rich reformed gas by steam reforming a raw material gas.

BRIEF DESCRIPTION OF THE DRAWINGS The longitudinal cross-sectional schematic which shows the reformer of this invention typically, and its AA cross-sectional schematic. The expanded sectional view of the metal honeycomb structure part in FIG. The expanded sectional view which shows the other example of the metal honeycomb structure part of FIG. The expanded sectional view which shows the other example of the metal honeycomb structure part of FIG. The cross-sectional schematic which shows the conventional self-oxidation internal heating type reformer typically, and its BB cross-sectional schematic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reformer 2 Preliminary reforming chamber 2a Outer cylinder 3 Main reforming chamber 3a Inner cylinder 4 Reforming catalyst layer 5 Mixed catalyst layer

6 Shift catalyst layer 7 High temperature shift catalyst layer 8 Low temperature shift catalyst layer 9 Supply unit 10 Discharge unit 11 Supply unit 12 Discharge unit

DESCRIPTION OF SYMBOLS 14 Supply pipe 15 Support plate 17 Air ejection part 20 Metal honeycomb structure 21 Flat strip 22 Corrugated strip

Claims (6)

A mixed catalyst layer 5 in which a reforming catalyst and an oxidation catalyst are mixed, a shift catalyst layer 6, and a supply pipe 14 for supplying an oxygen-containing gas for oxidation to the mixed catalyst layer 5. In a reformer of self-oxidation internal heating type that reforms to produce hydrogen-rich reformed gas,
The shift catalyst layer 6 is formed by supporting a shift catalyst on the metal honeycomb structure 20,
The metal honeycomb structure 20 is formed in a spiral shape with a composite plate in which a flat strip made of a thin strip metal plate and a corrugated strip bent in a corrugated shape are overlapped, leaving a tubular space at the center. And
The reformer characterized in that the tubular space constitutes the supply pipe 14, and the supply pipe 14 extends through the spiral center of the spiral metal honeycomb structure 20 to the mixed catalyst layer 5.   The reformer according to claim 1, wherein the metal honeycomb structure 20 has one or more spiral centers, and the supply pipe 14 passes through each of the spiral centers. In claim 1 or claim 2,
The metal honeycomb structure 20 is a reformer characterized in that the supply pipe 14 is disposed at one end edge of the composite plate, and the composite plate is formed in a spiral shape on the outer periphery thereof. In any one of Claims 1-2.
The mixed catalyst layer 5 comprises a mixture of a granular reforming catalyst and an oxidation catalyst, respectively. In claim 4,
An inner cylinder is formed on the outer periphery of the metal honeycomb structure 20, one end of the inner cylinder extends in the axial direction from the metal honeycomb structure 20, and the mixed catalyst layer 5 is provided in the extending portion. Characteristic reformer. A mixed catalyst layer 5 in which a reforming catalyst and an oxidation catalyst are mixed, a shift catalyst layer 6, and a supply pipe 14 for supplying an oxygen-containing gas for oxidation to the mixed catalyst layer 5 are steam reformed. In the manufacturing method of the self-oxidation internal heating type reformer that generates hydrogen-rich reformed gas,
A metal honeycomb structure 20 is formed by spirally winding a composite plate in which a flat strip made of a thin strip metal plate and a corrugated strip bent into a corrugated shape are wound around the supply pipe 14. In addition, a reformer manufacturing method is characterized in that the shift catalyst layer 6 is formed by supporting the shift catalyst in the spiral portion.