JP3904809B2 - Cylindrical hydrogen recovery system - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an apparatus for recovering hydrogen generated by steam reforming of a hydrocarbon gas.
[0002]
[Prior art]
Hydrogen is used in a wide range of applications such as basic raw materials, fuel cell fuels, and heat treatment atmospheres in various chemical industries, and steam reforming of gas fuel is known as a typical production method that meets small-scale demand. ing. The reformed gas obtained by steam reforming contains CO, CO ₂ , surplus H ₂ O, and the like. For example, when used as it is in a fuel cell, the cell performance is hindered. Therefore, before supplying the reformed gas to the fuel cell, it is necessary to remove subcomponents such as CO, CO ₂ and surplus H ₂ O.
[0003]
There is a hydrogen permeable membrane method using Pd—Ag, Ta or the like having an action of selectively permeating hydrogen to remove the subcomponent. The hydrogen permeable membrane is formed as a thin film on the surface of the heat resistant porous body (Japanese Patent Laid-Open Nos. 63-294925, 1-164419, etc.). The use of porous metal bodies with a gap has been studied.
The metal porous body on which the hydrogen permeable membrane is laminated is mounted on, for example, one surface of a hydrogen recovery apparatus to which a hydrogen extraction pipe is connected, and is embedded in the catalyst packed bed. The hydrogen gas generated by the steam reforming of the hydrocarbon gas selectively permeates the hydrogen permeable membrane, flows into the hydrogen recovery device, and is taken out of the system through the hydrogen take-out pipe.
[0004]
[Problems to be solved by the invention]
In a conventional hydrogen recovery apparatus, a thick plate is used for a structure in order to prevent deformation due to a heat cycle of heating to cooling. Therefore, the weight increases and a special jig is required to fix the reformer in the reformer. In addition, after forming the hydrogen passage hole and header by etching, cutting, electric discharge machining, etc., a hydrogen permeable film such as a Pd-Ag alloy is provided on the outer surface by laser welding, which requires labor and cost. , There is a problem in mass productivity.
[0005]
The present invention has been devised to solve such problems, and by using a structure formed by pressing a thin plate, a hydrogen recovery apparatus that is easy to manufacture, lightweight, and has sufficient strength. The purpose is to provide.
[0006]
[Means for Solving the Problems]
In order to achieve the object, the cylindrical hydrogen recovery apparatus of the present invention has a disk-shaped upper plate, a disk-shaped lower plate, and a disk-shaped upper plate and a disk-shaped lower plate formed with a hydrogen passage opening at the center. A plurality of reinforcing bones arranged at equal intervals in the circumferential direction, and a metal porous plate pasted on a cylindrical surface formed by a curved surface or an end face of the reinforcing bone, and a hydrogen permeable membrane laminated thereon A hydrogen extraction pipe connected to one or both of the disk-shaped upper plate and the disk-shaped lower plate, and hydrogen gas that has permeated the hydrogen permeable membrane and entered the internal hydrogen passage space from the hydrogen extraction pipe. It is characterized by being taken out of the system.
The disc-like upper plate, disc-like lower plate, reinforcing bone and metal porous plate are preferably made of ferritic stainless steel having a thermal expansion coefficient comparable to that of the material of the hydrogen permeable membrane.
[0007]
[Embodiment]
As shown in FIG. 1, for example, the hydrogen recovery apparatus 10 according to the present invention uses, as a structure, a cylindrical frame 11 formed by assembling and welding a stainless steel thin plate by press working, and a hydrogen permeable membrane 13 is laminated. The perforated metal plate 12 is wound around the cylindrical frame 11, and caps 14u and 14d are attached to the upper and lower ends of the cylindrical frame 11. Connected to the upper cap 14u is a hydrogen extraction pipe 15 for extracting hydrogen that has permeated through the hydrogen permeable membrane 13 and entered the hydrogen recovery apparatus 10 out of the system. The hydrogen take-out pipe 15 can be attached to the lower cap 14d or the upper and lower caps 14u, 14d.
[0008]
The hydrogen permeable membrane 13 is a thin film made of Pd-20% Ag alloy, Ta or the like and having a thickness of about 5 to 50 μm, and exhibits a selective permeability to hydrogen. The hydrogen permeable membrane 13 is fixed to the metal porous plate 12 by, for example, CO ₂ laser welding, YAG laser welding, microwave plasma welding, electron beam welding, or the like.
The metal porous plate 12 is a member made of stainless steel or the like having excellent heat resistance that reinforces the hydrogen permeable membrane 13, and the pores 12 a are formed to send hydrogen selectively permeated through the hydrogen permeable membrane 13 into the hydrogen recovery apparatus 10. Is drilled. Since the porous metal plate 12 made of stainless steel has substantially the same thermal expansion coefficient as that of the hydrogen permeable membrane 13, the peeling of the hydrogen permeable membrane 13 is prevented even when subjected to thermal fluctuations of heating and cooling.
[0009]
The pores 12a may be formed with a pore diameter of 0.1 to 1.5 mm so as not to increase the hydrogen gas passage resistance and to prevent the hydrogen permeable membrane 13 from being drawn into the hydrogen recovery apparatus 10. preferable. Further, in order to efficiently suck hydrogen generated by steam reforming of hydrocarbons into the hydrogen recovery apparatus 10, it is preferable to form the hydrogen permeable membrane 13 at an area ratio of 10% or more. The pores 12a having such a pore diameter are formed by electron beam machining, chemical etching, or the like. It is also possible to use a punching metal with holes of a predetermined size for the metal porous plate 12.
The cylindrical frame 11 has a plurality of reinforcing bones 18 interposed between a disk-shaped upper plate 16 and a disk-shaped lower plate 17 (FIG. 1b). The disc-like upper plate 16, the disc-like lower plate 17 and the reinforcing bone 18 are preferably made of stainless steel because heat resistance and high-temperature strength are required.
[0010]
The disc-like upper plate 16 and the disc-like lower plate 17 have hydrogen passage openings 16a, 17a formed in the center, and notches 16b, 17b into which the upper and lower ends of the reinforcing bone 18 are fitted at equal intervals on the periphery. (FIG. 1c). In the reinforcing bone 18, an upright piece 18 b is bent at a substantially right angle from a curved surface 18 a having a curvature along the peripheral edges of the disk-shaped upper plate 16 and the disk-shaped lower plate 17. Since the curved surface 18a and the upright piece 18b form an L-shaped cross section, the deformation resistance of the reinforcing bone 18 in the circumferential direction is increased. At the upper and lower ends of the reinforcing bone 18, a part of the curved surface 18 a and the upright piece 18 b are cut off by approximately the thickness of the disc-like upper plate 16 and the disc-like lower plate 17, thereby forming a fitting protrusion 18 c.
[0011]
When the fitting protrusion 18c is fitted into the notches 16b and 17b of the disc-like upper plate 16 and the disc-like lower plate 17, the upright piece 18b is directed toward the center of the cylinder, and the curved surface 18a becomes a part of the cylindrical surface ( FIG. 1d). By passing a plurality of reinforcing bones 18 to the disk-like upper plate 16 and the disk-like lower plate 17 at equal intervals in the circumferential direction, a cylinder having high deformation resistance and sufficient strength against vertical and circumferential stresses. The formwork 11 is assembled. In the long cylindrical hydrogen recovery apparatus 10, a single or plural intermediate plates 19 (FIG. 1 b) having the same shape are interposed between the disk-shaped upper plate 16 and the disk-shaped lower plate 17, thereby reinforcing the reinforcing bone 18. Deformation is more reliably prevented, and a predetermined hydrogen passage space S is secured.
[0012]
A lower cap 14d is attached to the lower end of the assembled cylindrical frame 11, and an upper cap 14u having a hydrogen take-out pipe 15 connected to the upper end is attached.
Next, the metal porous plate 12 on which the hydrogen permeable membrane 13 is laminated is attached to the cylindrical surface defined by the curved surface 18 a of the reinforcing bone 18. The metal perforated plate 12 is seam welded at the joint of the upper cap 14u and the lower cap 14d. Moreover, the metal porous plate 12 is spot-welded to the curved surface 18a of the reinforcing bone 18, the disc-like upper plate 16, and the disc-like lower plate 17 as necessary. Considering the welding operation, it is preferable that the upper and lower edge portions of the metal porous plate 12 are the welded portions 12b having no pores 12a.
[0013]
In this way, the hydrogen recovery apparatus 10 that is lightweight and has sufficient strength is assembled. Since the hydrogen recovery device 10 is reinforced by a plurality of reinforcing bones 18, a hydrogen passage space S is secured inside. Moreover, since the metal porous plate 12 on which the hydrogen permeable membrane 13 is laminated is supported by the reinforcing bone 18 from the inside, even if it is incorporated in a gas reforming apparatus in which a heating-cooling cycle is repeated, sufficient deformation resistance against thermal stress is provided. In addition, surface deformation and destruction are prevented, and stable hydrogen permselectivity is exhibited.
[0014]
The metal porous plate 12 can be supported by the end face of the reinforcing bone 18 (FIG. 2). In this case, a plurality of reinforcing bones 18 are provided between the disc-like upper plate 16 and the disc-like lower plate 17 so that the end face 18 d of the reinforcing bone 18 faces the peripheral edges of the disc-like upper plate 16 and the disc-like lower plate 17. Pass in the circumferential direction at equal intervals.
As the disk-shaped upper plate 16 and the disk-shaped lower plate 17, a bottomed cylindrical body in which flanges 16d and 17d rise from the peripheral edges of the disk-shaped bottom portions 16c and 17c is used. Hydrogen passage openings 16a and 17a are formed at the center of the bottom portions 16c and 17c, and notches 16e and 17e reaching the hydrogen passage openings 16a and 17a from the periphery are formed in the bottom portions 16c and 17c. The reinforcing bone 18 is made of an L-shaped material, and the upper and lower ends are inserted into the notches 16e and 17e. At this time, if a step 18e is provided at the upper and lower ends of the end face 18d, the reinforcing bone 18 is easily positioned with respect to the disc-like upper plate 16 and the disc-like lower plate 17 (FIG. 2b).
[0015]
In the structure of FIG. 2, the metal porous plate 12 on which the hydrogen permeable membrane 13 is laminated is supported by the end face 18d of the reinforcing bone 18, so that the number of pores 12a blocked by contact with the reinforcing bone 18 is small, and hydrogen permeation is performed. The effective area of the film 13 is increased. In addition, the rigidity of the reinforcing bone 18 is increased by the bent piece 18f, so that the deformation of the metal porous plate 12 is suppressed even when exposed to heat fluctuations of heating and cooling during hydrogen recovery, and a necessary hydrogen passage space S is secured ( FIG. 2c).
[0016]
The hydrogen recovery apparatus 10 is arranged inside the gas reforming apparatus 20 (FIG. 3) without the need for a fixing jig as in the prior art, and a hydrogen extraction pipe 15 is connected to the hydrogen extraction port 21 of the gas reforming apparatus 20. Connected. After the hydrogen recovery device 10 is disposed, the gas reforming device 20 is filled with a steam reforming catalyst 22 such as a catalyst in which Ni is supported on alumina. Since no fixing jig is required for mounting the hydrogen recovery device 10, the proportion of the internal space of the gas reforming device 20 occupied by the hydrogen recovery device 10 is small, and the amount of filling of the catalyst 22 can be increased accordingly. The steam reforming reaction efficiency of gas is improved.
[0017]
A hydrocarbon gas G such as city gas and water vapor V generated in the boiler 23 are fed into the gas reformer 20 filled with the hydrogen recovery device 10 and the catalyst 22, and a burner 24 into which compressed air is fed from the compressor 25 is externally supplied. When heated, a steam reforming reaction of CH ₄ + 2H ₂ O = 4H ₂ + CO ₂ proceeds. The generated hydrogen gas selectively permeates through the hydrogen permeable membrane 13 and is sent into the hydrogen recovery apparatus 10, and is taken out of the system through the hydrogen extraction pipe 12. Exhaust gas W other than hydrogen is discharged out of the system through the exhaust pipe.
Since hydrogen is removed from the reaction zone, the reaction equilibrium of CH ₄ + 2H ₂ O = 4H ₂ + CO ₂ is broken, and the steam reforming reaction is accelerated to the right. As a result, hydrogen is generated with sufficient reaction efficiency even at a relatively low temperature of about 500 to 550 ° C.
[0018]
The atmospheric pressure of the hydrogen recovery device 10 is preferably about 0.1 to 1 MPa lower than the atmospheric pressure of the gas reforming device 20 in order to efficiently introduce hydrogen into the hydrogen recovery device 10. By maintaining this pressure difference, that is, the inside of the hydrogen recovery apparatus 10 in a reduced pressure state, the flow rate of hydrogen gas selectively permeating the hydrogen permeable membrane 13 is increased, and the steam reforming reaction is further promoted. Even if a pressure difference is applied, deformation of the hydrogen recovery apparatus 10 is prevented because the metal porous plate 12 is supported from the inside by the reinforcing bone 18.
[0019]
【The invention's effect】
As described above, the hydrogen recovery apparatus of the present invention supports the metal perforated plate on which the hydrogen permeable membrane is laminated from the inside with the reinforcing bone assembled to the cylindrical frame, so that the sheet metal processing of the stainless steel plate is possible. Despite being a molded lightweight cylindrical frame, it has sufficient strength and can be placed inside the gas reformer without the need for a fixture. Therefore, the proportion occupied by the hydrogen recovery device is small, and a large amount of catalyst can be filled in the gas reforming device, and the efficiency of the steam reforming reaction is increased. Moreover, even if a pressure difference is created between the gas reformer and the interior of the hydrogen recovery unit in order to remove the hydrogen generated in the steam reforming reaction from the reaction zone, the hydrogen recovery unit is not deformed. Maintain the shape of the period.
[Brief description of the drawings]
FIG. 1 is an overall perspective view of a cylindrical hydrogen recovery device according to the present invention (a), a perspective view of a cylindrical frame body (b), and a horizontal sectional view of a cylindrical hydrogen recovery device (c).
FIG. 2 is a side sectional view of a cylindrical hydrogen recovery device that supports a metal porous plate at the end face of a reinforcing bone (a), and an explanatory view showing fitting of the reinforcing bone to the disc-like upper plate and the disc-like lower plate (b). And horizontal sectional view (c)
[Fig. 3] Schematic diagram of gas reformer [Explanation of symbols]
DESCRIPTION OF SYMBOLS 10: Cylindrical hydrogen recovery apparatus 11: Cylindrical frame 12: Metal perforated plate 13: Hydrogen permeable membrane 14u, 14d: Cap 15: Hydrogen extraction pipe 16: Disk-shaped upper plate 17: Disk-shaped lower plate 18: Reinforcement bone S : Hydrogen passage space

Claims (3)

  A plurality of disc-shaped upper plate, disc-like lower plate having a hydrogen passage opening formed in the center, and a disc-like upper plate and disc-like lower plate arranged at equal intervals in the circumferential direction. Reinforced bone and a metal perforated plate attached to a cylindrical surface formed by a curved surface or an end surface of the reinforcing bone and laminated with a hydrogen permeable membrane, and either or both of a disk-shaped upper plate and a disk-shaped lower plate A cylindrical hydrogen recovery apparatus comprising a hydrogen extraction pipe connected thereto, wherein hydrogen gas that has passed through the hydrogen permeable membrane and entered the hydrogen passage space is taken out of the system from the hydrogen extraction pipe.   The cylindrical hydrogen recovery apparatus according to claim 1, wherein the disk-shaped upper plate, the disk-shaped lower plate, the reinforcing bone, and the metal porous plate are made of ferritic stainless steel. The cylindrical hydrogen recovery apparatus according to claim 1 or 2 installed in a steam reformer .

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