JP2004175581A - Internal heating steam reformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize the downsizing and weight reduction of an internal heating steam reformer which performs steam reforming by the auto-oxidation of a raw material gas in the presence of oxygen. <P>SOLUTION: The steam reformer is equipped with a reforming reactor 2 which reforms the raw material gas into a reformed gas and a heat-exchanger 3 which performs heat-exchange between an oxygen-containing gas supplied to the reforming reactor 2 and the produced reformed gas. The reforming reactor 2 and the heat-exchanger 3 are located adjacently to each other inside a casing 10. The reformed gas flowing out of the reforming reactor 2 directly flows into the heat-exchanger 3 through an internal passage 11 installed in the casing 10. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an internal heat type steam reforming apparatus for performing steam reforming by self-oxidizing a raw material gas in the presence of steam and oxygen, and in particular, by reducing the size and height by arranging a reforming reaction section and a heat exchange section adjacent to each other. The present invention relates to an internal heat type steam reformer that achieves efficiency.
[0002]
[Prior art]
Steam reforming of a mixture of raw material gas such as hydrocarbons such as methane, aliphatic alcohols such as methanol, or ethers such as dimethyl ether and steam in the presence of a steam reforming catalyst to generate hydrogen-rich reformed gas An apparatus for performing this is conventionally known. Such a steam reformer can be used to supply hydrogen to an industrial, domestic, or vehicle-mounted fuel cell.
The reforming reaction section, which is a main component of the steam reforming apparatus, includes an external heat type in which heat required for the steam reforming reaction is supplied from the outside, and an internal heat type in which internal autoxidation heat is used.
[0003]
In the former external heat type, the wall of the reforming reaction section is heated from the outside with combustion gas from a combustion section provided with a burner or the like, and heat required for the internal reforming reaction is supplied through the wall. In the latter internal heat type, a part of the raw material gas is first reacted with oxygen inside the reforming reaction section, and then the steam reforming reaction is performed using the oxidation heat as the reforming reaction heat.
[0004]
When generating a hydrogen-rich reformed gas by steam reforming, the reaction formula when methane is used as a raw material gas is as follows:
CH ₄ + 2H ₂ O → CO ₂ + 4H ₂ (1)
The temperature required for the steam reforming reaction is in the range of 700 to 750 ° C.
[0005]
When performing a partial oxidation reaction, the reaction formula when methane is used as a raw material gas is as follows:
_{CH 4 + 1/2 · O 2 →} CO + 2H 2 (2)
The temperature required for the partial oxidation reaction is set to 250 ° C. or more. For example, Patent Document 1 is known as a steam reforming apparatus using the internal heating type reforming reaction section.
[0006]
[Patent Document 1]
JP 2001-192201 A
FIG. 7 is a schematic diagram of a conventional internal heat type steam reformer. The steam reforming apparatus 1 includes a reforming reaction section 2 and a heat exchange section 3. The reforming reaction section 2 has an outer reaction chamber 4 and an inner reaction chamber 5 communicating with each other at an upper portion. The outer reaction chamber 4 is filled with a steam reforming catalyst layer, and the inner reaction chamber 5 is steam-reformed in order from the top. The mixed catalyst layer, the heat transfer particle layer and the shift catalyst layer in which the catalyst and the oxidation catalyst are mixed are filled. On the other hand, the heat exchange section 3 exchanges heat between the oxygen-containing gas (usually air) 33 supplied from the outside and the generated high-temperature reformed gas 34 to recover thermal energy. Then, the heated oxygen-containing gas 33 is supplied to the reforming chamber 2 through a pipe.
[0008]
The steam reforming catalyst in the outer reaction chamber 4 is heated by the heat transfer from the inner reaction chamber 5. When a mixture of the raw material gas 32 and the steam supplied from the pipe 6 is introduced into the lower part of the outer reaction chamber 4, a part of the raw material gas 32 reacts while passing through the steam reforming catalyst layer in a relatively high temperature state. The resulting reformed gas and the unreacted mixture flow into the inner reaction chamber 5. In the inner reaction chamber 5, a part of the raw material gas first reacts with the oxygen-containing gas supplied from the pipe 7 in the upper mixed catalyst layer and self-oxidizes. By raising the temperature to the reaction temperature, the remaining mixture is steam reformed and converted into a hydrogen-rich reformed gas 34.
[0009]
The generated reformed gas 34 flows into the heat transfer particle layer filled on the downstream side, where it exchanges heat and then flows into the shift catalyst layer. The thermal energy of the heat transfer particle layer is transmitted to the outer reaction chamber 4 as described above. In the reformed gas that has flowed into the shift catalyst layer, the slightly remaining carbon monoxide is reduced by the reaction with the shift catalyst, and is then supplied from the pipe 8 to the utilization equipment such as a fuel cell via the heat exchange unit 3. The oxygen-containing gas 33 is supplied from the pipe 9 to the heat exchange unit 3, where it is heated and supplied to the reforming reaction chamber 2 via the pipe 7.
[0010]
[Problems to be solved by the invention]
In the conventional steam reforming apparatus 1 shown in FIG. 7, a reforming reaction section 2 and a heat exchange section 3 are provided apart from each other, and as an example, a high-temperature reforming of about 200 ° C. flows out of the reforming reaction section 2. The gas 34 is supplied to the heat exchange unit 3 via the external pipe 8. Therefore, a portion of the pipe 8 between the reforming reaction section 2 and the heat exchange section 3 is covered with a heat insulating layer, and heat is prevented from surroundings to prevent heat loss.
[0011]
However, if the reforming reaction section 2 and the heat exchange section 3 are provided apart from each other, the space efficiency of the apparatus is reduced and the apparatus size is increased. In addition, since the reforming reaction section 2 and the heat exchange section 3 are provided independently, the heat insulating wall portion increases and the heat insulating coating layer in the pipe 8 increases the weight of the apparatus. In particular, when supplying hydrogen to the fuel cell mounted on the vehicle using the steam reforming apparatus 1, it is necessary to avoid increasing the size and weight of the apparatus as much as possible.
Therefore, an object of the present invention is to solve such a problem in the conventional steam reformer, and an object of the present invention is to provide a steam reformer that has solved the problem.
[0012]
[Means for Solving the Problems]
The present invention for solving the above-mentioned problems includes a reforming reaction section 2 for steam reforming the raw material gas 32 into a hydrogen-rich reformed gas 34;
In the internal heat type steam reforming apparatus including the heat exchange unit 3 for performing heat exchange between the oxygen-containing gas 33 supplied to the reforming reaction unit 2 and the generated reformed gas 34,
The reforming reaction section 2 and the heat exchange section 3 are adjacent in the same casing 10,
An internal heat type steam reforming wherein the reformed gas 34 flowing out of the reforming reaction section 2 flows directly into the heat exchange section 3 through the internal flow path 11 provided in the casing 10. An apparatus (claim 1).
[0013]
In the above apparatus, the casing is constituted by the reforming reaction section block and the heat exchange section block, and the reforming reaction section and the heat exchange section can be adjacent to each other by integrating the reforming reaction section block and the heat exchange section block. (Claim 2).
[0014]
In any one of the above apparatuses, the oxygen-containing gas 33 flowing out of the heat exchange section may be configured to directly flow into the reforming reaction section via an internal flow path provided in the casing.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a principle view schematically showing an internal heat type steam reforming apparatus according to the present invention. The same parts as those in the conventional apparatus in FIG. 7 are denoted by the same reference numerals. In the figure, 1 is a steam reforming apparatus, 2 is a reforming reaction section, 3 is a heat exchange section, 4 is an outer reaction chamber, 5 is an inner reaction chamber, 6 is a pipe for supplying a mixture of raw material gas and steam, 7 is A pipe for supplying an oxygen-containing gas such as air heated by heat exchange to the reforming reaction section 2, a pipe 8 for supplying a reformed gas to load equipment, and a pipe 9 pressurized from a pressurized air supply means (not shown). A pipe for supplying an oxygen-containing gas (usually pressurized air) to the heat exchange unit 3, a casing 10, an internal flow passage 11, a baffle plate 12, a nozzle unit 13, and a porous member 14-17 for supporting a catalyst. , A cooling pipe, and 31 an outer fin. Reference numeral 32 denotes a source gas (including steam), 33 denotes an oxygen-containing gas, and 34 denotes a reformed gas.
[0016]
The reforming reaction section 2 and the heat exchange section 3 are disposed adjacent to each other inside the same casing 10 constituted by a closed container. Note that a heat-insulating layer (not shown) is usually provided inside the casing 10.
The reforming reaction section 2 includes an outer reaction chamber 4 formed in a cylindrical shape, and an inner reaction chamber 5 arranged in the outer reaction chamber 4 in parallel with the outer reaction chamber 4 and formed in a cylindrical shape. The outer reaction chamber 4 is filled with a steam reforming catalyst layer supported by a support plate 14, and the inner reaction chamber 6 is a mixed catalyst layer obtained by mixing a steam reforming catalyst and an oxidation catalyst supported by a support plate 15 in order from the top. And a heat transfer particle layer supported by the support plate 16 and a shift catalyst layer supported by the support plate 17.
[0017]
The steam reforming catalyst layer is a catalyst layer for steam reforming the raw material gas 32. For example, the steam reforming catalyst layer can be formed of a catalyst similar to the reforming reaction catalyst disclosed in JP-A-2001-192201. Ni-based reforming catalyst such as ₂ · _{Al 2 O 3} is desirable. The reforming reaction catalyst such as _{WS 2 -SiO 2 · Al 2 O} 3 and _{NiS-WS 2 · SiO 2 ·} Al 2 O 3 can also be used.
Further, as the heat transfer particles constituting the heat transfer particle layer, for example, alumina balls can be used.
[0018]
The oxidation catalyst uniformly dispersed in the mixed catalyst layer oxidizes the raw material gas in the mixture of the raw material gas and steam, and raises the temperature of the mixed catalyst layer to the steam reforming reaction temperature by the heat of oxidation. Platinum (Pt) or palladium (Pd) can be used. The mixing ratio of the oxidation catalyst to the steam reforming catalyst is selected in the range of about 1 to 5% depending on the type of the raw material gas to be steam reformed. For example, when methane is used as the raw material gas, 3% ± 2% In the case of methanol, the mixing ratio is desirably about 2% ± 1%.
[0019]
As the heat transfer particles constituting the heat transfer particle layer, for example, alumina balls can be used.
As the shift catalyst for forming the shift catalyst layer, a mixture of CuO—ZnO ₂ , Fe ₂ O ₃ , Fe ₃ O _4, or copper oxide can be used. However, when the reaction is performed at 700 ° C. or higher, it is desirable to use Cr ₂ O ₃ .
[0020]
The lower part of the outer reaction chamber 4 communicates with a pipe 6 for supplying a mixture of the raw material gas 33 and the vapor, and the upper part communicates with the upper part of the inner reaction chamber 5. The lower part of the inner reaction chamber 5 communicates with the inside of the heat exchange unit 3 via the internal flow path (gas induction space provided inside the casing) 11 of the casing 10, and the inside of the heat exchange unit 3 is provided with an outer fin 31 and a cooling unit. One or more tubes 18 are arranged.
The inlet side of the cooling pipe 18 is connected to the pipe 9, and the outlet side is connected to the pipe 7. Further, the tip of the pipe 7 extends to the reforming reaction section 2, and the tip is connected to the upper part of the inner reaction chamber 5, that is, the nozzle section 13 arranged in the mixed catalyst layer portion where the steam reforming catalyst and the oxidation catalyst are mixed. .
[0021]
Next, the operation of the steam reformer 1 of FIG. 1 will be described.
When a mixture of the raw material gas 33 and the steam is supplied from the pipe 6 to the outer reaction chamber 4, the temperature is raised to a steam reforming temperature, for example, 500 ° C. or more by heat transfer from the inner reaction chamber 5, and the steam reforming at a high temperature is performed. A portion thereof is steam reformed while passing through the catalyst layer. The generated reformed gas 34 flows into the upper part of the inner reaction chamber 5 together with the remaining mixture of the raw material gas and the steam. In the inner reaction chamber 5, the oxygen-containing gas 33 ejected from the nozzle portion 13 and a part of the raw material gas react with each other in the upper mixed catalyst layer, and the mixed catalyst layer is heated to the reforming reaction temperature by the heat of oxidation. Then, a steam reforming reaction is performed while the mixture of the remaining raw material gas and steam passes through the mixed catalyst layer to generate a hydrogen-rich reformed gas 34.
[0022]
The reformed gas 34 generated in the mixed catalyst layer flows into the heat transfer particle layer, where it exchanges heat and supplies its heat energy to the outer reaction chamber 4 before flowing into the shift catalyst layer. In the shift catalyst layer, the carbon monoxide slightly remaining in the reformed gas 34 is reduced, and the high-temperature reformed gas 34 of about 200 ° C. flowing out of the shift catalyst layer flows into the heat exchange section 3 through the internal flow path 11.
[0023]
The reformed gas 34 flowing into the heat exchange unit 3 changes its flow direction at one end of the baffle plate 12 (on the front side of the drawing), flows around the outer periphery of the cooling pipe 18, and flows through the inside of the cooling pipe 18. After exchanging heat with 33, it is supplied to utilization equipment such as a fuel cell via the pipe 8. Further, the high-temperature oxygen-containing gas 33 flowing out of the heat exchange unit 3 is supplied to the mixed catalyst layer from the nozzle unit 13 disposed above the inner reaction chamber 5 via the pipe 7.
[0024]
As described above, the reforming reaction section 2 and the heat exchange section 3 are disposed adjacent to each other in the same casing 10, and the reformed gas 34 flowing out of the reforming reaction section 2 is provided inside the casing 10 through the internal flow path 11. By flowing directly into the heat exchange section 3 via the heat exchanger, the space efficiency of each section is improved, and the size and weight of the apparatus are reduced. Further, since the heat insulating portion in the portion adjacent to the reforming reaction section 2 and the heat exchange section 3 is reduced, the size and weight of the apparatus can be reduced from that aspect as well. Therefore, the steam reforming apparatus 1 according to the present invention is particularly suitable for use in a vehicle.
[0025]
FIG. 2 is an exploded perspective view showing an embodiment in which the casing 10 of the steam reformer 1 is divided into two blocks, FIG. 3 is a partially cutaway front view showing an assembled state, FIG. FIG. 5 is a left side view. The operation of this example is basically the same as that of FIG. The same components as those in FIG. 1 are denoted by the same reference numerals.
The steam reforming apparatus 1 in this example divides the casing 10 into a container-shaped heat exchange section block 21 that houses the heat exchange section 3 and a container-shaped reformer section block 20 that houses the reformer section 2, The reforming reaction unit block 20 and the heat exchange unit block 21 are connected and integrated by, for example, bolt connection, flange connection, welding, or the like, thereby bringing the reforming reaction unit 2 and the heat exchange unit 3 into an adjacent state. In the case of performing bolt connection or flange connection, heat-tight packing is interposed at the connection portion to ensure airtightness.
[0026]
A pipe 6 for supplying a mixture of a raw material gas 32 and steam is connected to the reforming reaction section block 20, and a pipe 7 for supplying an oxygen-containing gas 33 heated in the heat exchange section 3 is connected to an upper end thereof. The pipe 6 communicates with the lower portion of the outer reaction chamber 4 in the reforming reaction section block 20, and supplies a mixture of the raw material gas 32 and the steam uniformly to each part of the outer reaction chamber 4 through the plurality of holes 6a.
The pipe 7 for supplying the heated oxygen-containing gas 33 branches in the reforming reaction section block 20 and communicates with the upper portions of the three inner reaction chambers 5, respectively.
[0027]
A plurality of (two in this example) flat cooling pipes 18 are arranged in parallel in the heat exchange block 21, inner fins 18 a are arranged inside the cooling pipes 18, and outer fins 31 are fixed on the outer surface side. Have been. Further, a plurality of connecting portions 24 for connecting the pipe 9 for supplying the oxygen-containing gas 33 to one inlet side of the cooling pipe 18 and a plurality of connecting portions 25 are provided on the outlet side. The plurality of connecting portions 24 and 25 are connected by pipes for branching and merging, and are connected to external pipes. The plurality of connection portions 24 and 25 are connected to both ends of each cooling pipe 18 in the heat exchange block 21 by means such as brazing.
The operation of each part is the same as that of FIG.
[0028]
By dividing the casing 10 into two blocks in this manner, mass production of the device is facilitated and the size of the device is further reduced. When the reforming reaction section block 20 and the heat exchange section block 21 are detachably connected by bolt connection, flange connection, or the like, maintenance and inspection of the inside thereof are facilitated.
[0029]
FIG. 6 shows a modification of the steam reformer shown in FIG. This example is different from the example of FIG. 1 in that the oxygen-containing gas flowing out of the heat exchange section 3 is formed inside the casing 10, specifically, an internal flow path 30 formed along the inside of the heat insulation layer (this example). (Internal piping or internal duct) supplies the liquid to the nozzle portion 13 disposed above the inner reaction chamber 5, and the other configuration is the same as described above. Therefore, the same parts as those in FIG. 1 are denoted by the same reference numerals, and duplicate description will be omitted.
[0030]
By supplying the oxygen-containing gas flowing out of the heat exchange unit 3 to the inner reaction chamber 5 through the internal flow path 30 in the casing 10 without using the external pipe 7, the space efficiency is further improved as compared with the example of FIG. This makes it easier to reduce the size of the device. Further, since the heat insulating layer at the pipe 7 is not required, the weight of the entire apparatus can be reduced.
Even in the case of the configuration shown in FIG. 6, the casing 10 can be divided into two blocks as shown in FIG. In that case, the joint of the internal passage 30 on the division surface of the reforming reaction section block 20 and the heat exchange section block 21 is sealed with packing to ensure the airtightness.
[0031]
【The invention's effect】
As described above, in the internal heat type steam reforming apparatus according to the present invention, the reforming reaction section and the heat exchange section are adjacent to each other in the same casing, and the reformed gas flowing out of the reforming reaction section is provided in the casing. The heat exchanger is configured to directly flow into the heat exchange section via the internal flow path.
With such a configuration, the space efficiency is improved, and the heat insulation portion and the pipe heat insulation in the portion adjacent to the reforming reaction section and the heat exchange section can be omitted, so that the size of the apparatus can be reduced and the weight can be reduced. Therefore, the device can be reduced in size and weight, and can be suitably used particularly for a vehicle.
[0032]
In the above apparatus, the casing is constituted by the reforming reaction section block and the heat exchange section block, and the reforming reaction section and the heat exchange section can be adjacent to each other by integrating the reforming reaction section block and the heat exchange section block. it can. By blocking the casing in this way, mass production of the device is facilitated and the entire device is more easily reduced in size. When the reforming reaction section block 20 and the heat exchange section block 21 are detachably connected by bolt connection, flange connection, or the like, maintenance and inspection of the inside thereof are facilitated.
[0033]
In any one of the above apparatuses, the oxygen-containing gas flowing out of the heat exchange section may be configured to directly flow into the reforming reaction section via an internal flow path provided in the casing. In this case, the space efficiency of the device can be further increased, so that the device can be more easily miniaturized. Further, since the heat insulating layer for external piping is not required, the weight of the entire device can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic view of an internal heat type steam reforming apparatus according to the present invention.
FIG. 2 is a perspective view showing an embodiment in which a casing 10 of the steam reformer 1 is divided into two blocks.
FIG. 3 is a partially broken front view showing the assembled state.
FIG. 4 is a plan view of the same.
FIG. 5 is a left side view of the same.
FIG. 6 is a schematic view of a modification of the steam reformer shown in FIG.
FIG. 7 is a schematic view of a conventional internal heat type steam reforming apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steam reformer 2 Reforming reaction part 3 Heat exchange part 4 Outer reaction chamber 5 Inner reaction chamber 6-9 Pipe 6a Hole 10 Casing 11 Internal flow path 12 Baffle plate 13 Nozzle part 14-17 Support plate 18 Cooling pipe 18a Fin 20 Reforming reaction block 21 Heat exchange block 24, 25 Connection 30 Internal flow path 31 Outer fin 32 Raw material gas 33 Oxygen-containing gas 34 Reformed gas

Claims (3)

A reforming reaction section 2 for steam reforming the raw material gas 32 into a hydrogen-rich reformed gas 34;
In the internal heat type steam reforming apparatus including the heat exchange unit 3 for performing heat exchange between the oxygen-containing gas 33 supplied to the reforming reaction unit 2 and the generated reformed gas 34,
The reforming reaction section 2 and the heat exchange section 3 are adjacent in the same casing 10,
An internal heat type steam reforming wherein the reformed gas 34 flowing out of the reforming reaction section 2 flows directly into the heat exchange section 3 through the internal flow path 11 provided in the casing 10. apparatus. In claim 1,
The casing 10 is constituted by a reforming reaction section block 20 and a heat exchange section block 21;
A unit-type internal heat steam reformer, wherein the reforming reaction section 2 and the heat exchange section 3 are adjacent to each other by integrating the reforming reaction section block 20 and the heat exchange section block 21. In claim 1 or 2,
An internal heat type steam reforming apparatus characterized in that the oxygen-containing gas 33 flowing out of the heat exchange section 3 flows directly into the reforming reaction section 2 through the internal flow path 30 provided in the casing 10.

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