JP2013212968A - Hydrogen generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that it is necessary to make the shortest part of an opening hole of a tray to be less than 1 mm for using a catalyst of φ1 to φ1.5, and meanwhile, when a tray is to be fabricated by press working with the assumption of mass production, a hole with a size less than plate thickness cannot be opened and consequently the plate thickness is obliged to be less than 1 mm, and when the plate thickness of the tray is set to be less than 1 mm, the tray falls into a state of insufficient strength and is transformed durably, and the catalyst falls, and concern for a stop of operation due to passage occlusion is caused.SOLUTION: A first supporting plate 51 which has small plate thickness and in which a hole with a size smaller than that of a catalyst can be made, and a second supporting plate 52 which has large plate thickness for keeping the strength while holding a gap between each other, are installed. The catalyst is prevented from falling by the first supporting plate 51, and strength as the tray can be kept by the second supporting plate 52.

Description

  The present invention relates to a hydrogen generator that generates a fuel gas containing hydrogen using a hydrocarbon compound as a raw material and supplies the fuel gas to a fuel cell.

  A fuel cell system supplies a hydrogen-containing gas and an oxygen-containing gas to a fuel cell stack (hereinafter simply referred to as a “fuel cell”) that is a main body of a power generation unit, and advances an electrochemical reaction between hydrogen and oxygen. It is a system that takes out the chemical energy generated by this as electric energy and generates electricity. In addition, high-efficiency power generation is possible, and heat energy generated during power generation operation can be easily used, so development is being promoted as a distributed power generation system that can achieve high energy use efficiency. ing.

  In general, the infrastructure of hydrogen-containing gas is often not established, and a conventional fuel cell system is provided with a hydrogen generator equipped with a reforming unit that generates reformed gas (hydrogen-containing gas). ing. The hydrogen generator uses water and natural gas supplied from existing infrastructure as the main component, or LPG as a raw material, and is modified at a temperature of 600 ° C to 700 ° C using a Ru catalyst or Ni catalyst. A reformed gas is generated by a quality reaction. In particular, in order to heat the reforming section to a high temperature, the reforming section is provided with a combustion section such as a burner. In addition, the reformed gas obtained by the reforming reaction usually contains carbon monoxide derived from the raw material, and if the concentration is high, the power generation characteristics of the fuel cell are degraded. Therefore, in addition to the reforming unit, the hydrogen generator includes a Cu—Zn-based catalyst that reduces carbon monoxide by advancing a shift reaction between carbon monoxide and water vapor at a temperature of 200 ° C. to 350 ° C. A metamorphic part, a selective oxidation part that selectively oxidizes carbon monoxide at a temperature of 100 ° C. to 200 ° C. to further reduce carbon monoxide, and methane that reduces carbon monoxide by selectively methanation In many cases, a reaction section such as a selective removal section such as a decontamination section is provided.

  Each reaction can be performed by filling the reaction part with a granular catalyst and allowing the raw material to pass through. The reforming section, the conversion section, and the selective oxidation section are each installed in the vertical direction, and each granular catalyst is held by a shelf installed at the lower part of each reaction section. Although it is necessary to open a hole for circulating gas in the shelf, in Patent Document 1, the hole in the shelf is made smaller than the catalyst particle diameter so that the catalyst does not fall out of the opening in the shelf. I have to. In Patent Document 2, the shelf uses a support plate such as a mesh body. Specifically, Patent Literature 3 describes that the particle diameter of the catalyst is φ3 mm, and the shelf is made of a punching metal having a hole diameter (about φ2 mm) smaller than the size of the catalyst.

  On the other hand, in order to fully disseminate fuel cell systems as household equipment, it is necessary to reduce the size in terms of installation space and cost, and development is underway to minimize each part including the reaction part. .

JP-A-8-208202 JP 2010-1113970 A JP 2011-006289 A

  The developer selected a catalyst with a diameter of 3 mm, which is a common particle size, and the shelf has an opening hole in the shelf so that the catalyst does not pass through the shelf even if the catalyst size varies slightly. Designed the equipment so that the shortest part would not be less than 1 mm. In order to reduce the size of the hydrogen generator, it is necessary to reduce the capacity of the catalyst, and in order to increase the amount of catalytic activity per unit volume, it was considered to employ a catalyst having a smaller particle diameter. In order to reduce the catalyst diameter to about φ1 to 1.5 mm, the opening of the shelf must be less than 1 mm (for example, 0.7 to 0.8 mm) in order to prevent the catalyst from falling off. is there. However, the shelf always has the role of supporting the weight of the catalyst, and the strength enough to withstand the force that the catalyst is pushed down by repeated expansion and contraction due to thermal deformation of the reactor due to repeated start and stop of the equipment Is required. Therefore, it has been experimentally grasped that the thickness of the shelf must be at least 1 mm. In order to mass-produce a shelf with a thickness of 1 mm by press working, the opening hole has an opening smaller than the plate thickness in consideration of severe damage to the mold during press working and consumption of the mold. It can't be a hole. Thus, in order to use the catalyst of φ1 to φ1.5, it is necessary to make the shortest portion of the opening hole of the shelf less than 1 mm, and the plate thickness of the shelf must be less than 1 mm. If the plate thickness of the shelf is less than 1 mm, the shelf will be insufficient in strength, and may be deformed in a durable manner, causing the catalyst to fall, and there is a concern that the operation may be stopped due to passage blockage.

In order to solve the conventional problem, the hydrogen generator of the present invention is:
A reaction vessel containing a granular catalyst;
A first support plate that is disposed inside the reaction vessel, has a plurality of openings, and supports the granular catalyst;
A second support plate supporting the first support plate and having a plurality of openings formed therein;
With
The first support plate is disposed on the upper side of the first support plate in the direction of gravity with a gap from the second support plate, and is thinner than the second support plate, and has an opening in the first support plate. Is configured to be smaller than the opening of the second support plate.

  With this configuration, the passage of the catalyst can be prevented by the first support plate, and the strength as the shelf can be maintained by the second support plate.

  Further, the second support plate is formed with a protrusion for supporting the first support plate that is convex upward in the gravity direction. With this configuration, the first support plate and the second support plate can always maintain a constant gap. Further, when the protrusion is formed by press working, it can serve as a rib of the second support plate and can increase the strength.

  The distance between the first support plate and the second support plate is configured to be greater than the thickness of both the first support plate and the second support plate. With this configuration, the opening hole of the first support plate and the opening hole of the second support plate do not overlap each other, and even if two support plates are stacked, it is possible to avoid a reduction in the gas flow path area.

  Thus, when using a catalyst with φ1 to φ1.5, the shelf is deformed by preventing the catalyst from dropping out from the opening hole of the shelf and securing the plate thickness of the shelf at least 1 mm. Thus, the two problems of preventing the catalyst from dropping and stopping the operation due to the passage blockage can be satisfied.

  The hydrogen generator of the present invention can use a catalyst having a particle size smaller than the plate thickness of the shelf. In addition, the shelf strength can be increased by providing the protrusions by pressing.

Sectional drawing of the principal part of the hydrogen generator in Embodiment 1 of this invention The principal part enlarged view of the hydrogen generator in Embodiment 2 of this invention

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, in all the drawings, only components necessary for explaining the present invention are extracted and illustrated, and other components are not illustrated. Furthermore, the present invention is not limited to the following embodiment.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a main part of a hydrogen generator 1 according to a first embodiment of the present invention, and FIG. 2 is a partially enlarged view of FIG.

  In the reactor 31, the middle cylinder 7 having the middle cylinder bottom plate 8 is disposed outside the inner cylinder 5 having the inner cylinder bottom plate 6. An outer cylinder 15 having an outer cylinder bottom plate 16 is disposed outside the middle cylinder 7. The inner cylinder 5, the middle cylinder 7, and the outer cylinder 15 are arranged in a substantially concentric shape. The middle cylinder bottom plate 8 is provided with a middle cylinder bottom plate through-hole 9 at the center thereof. In addition, the upper part of the inner cylinder 5, the middle cylinder 7, and the outer cylinder 15 are each appropriately connected and configured in a substantially cylindrical shape (detailed connection relations of the upper part are omitted). ).

  The reactor 31 includes a preheating unit 23 that evaporates water supplied from the water supply path 3 and preheats a mixed gas of raw material and water vapor. In addition, the reforming unit 20 that promotes the reforming reaction between the raw material supplied from the raw material supply path 4 and the steam, and the carbon monoxide in the hydrogen-containing gas generated in the reforming unit 20 and the steam are subjected to a modification reaction. Thus, it has a shift section 25 for reducing the carbon monoxide concentration of the hydrogen-containing gas. Further, the carbon monoxide remaining in the hydrogen-containing gas after passing through the shift conversion section 25 is mainly oxidized using air supplied from the air supply section 19 to the hydrogen-containing gas after passing through the shift conversion section 25. The selective oxidation unit 26 is removed. The metamorphic unit 25 and the selective oxidation unit 26 constitute a carbon monoxide reduction unit.

  The reforming unit 20 is filled with a Ru-based reforming catalyst 21 having a spherical shape of about φ1 to 2 mm. A first support plate 51 having a plurality of opening holes smaller than the particle diameter of the reforming catalyst 21 is disposed below the reforming catalyst. Below the first support plate 51, a second support plate 52 having a certain strength as a shelf is provided with a gap. The second support plate 52 is also formed with a plurality of opening holes. The opening hole of the second support plate 52 has a shortest portion of 1 mm, and the second support plate 52 has a thickness of 1 mm or more.

  The first support plate 51 is smaller in thickness than the second support plate 52, and a plurality of opening holes smaller than the opening holes of the second support plate 52 are formed.

  Thus, the catalyst is prevented from falling off by the first support plate 51, and the strength as a shelf is maintained by the second support plate 52.

  An assembly process for filling the reforming catalyst 21 will be described. At the time of assembly, the reactor 31 is fixed in the vertical direction and fixed to the table, and the portion between the inner cylinder 5 and the middle cylinder 7 is filled with the reforming catalyst 21. When charging of the reforming catalyst 21 for a predetermined volume is completed, the first support plate 51 is placed between the inner cylinder 5 and the middle cylinder 7 and the upper portion of the reforming catalyst 21 that has been filled (ie, the lower position during operation). ). Thereafter, the second support plate 52 is attached to the inner surface of the middle cylinder 7 by welding.

  The second support plate 52 is formed with a protrusion 53 that is convex toward the first support plate 51. With this configuration, reliable positioning can be performed when the second support plate 52 is attached to the middle cylinder 7 by welding. Further, since the weight of the reforming catalyst 21 is applied to the first support plate 51 during operation, the first support plate 51 and the second support plate 52 can always maintain a constant gap.

  In addition, when the protrusion 53 is formed by press working, it can serve as a rib for the first support plate 51 to increase the strength.

  Further, the distance between the first support plate 51 and the second support plate 52 is configured to be greater than the thickness of both the first support plate 51 and the second support plate. When the distance is shorter than this, the gap above the opening hole of the second support plate 52 is not sufficient, so that resistance when the gas that has passed through the first support plate 51 passes through the opening hole of the second support plate 52. Thus, there is a concern that the substantial flow area becomes narrow and a sufficient amount of gas cannot be supplied by the booster pump.

  Next, other configurations of the hydrogen generator 1 will be described.

  The shift portion 25 is provided with a Cu-Zn shift catalyst having a cylindrical shape of approximately φ3 mm and a height of 3 mm, and the selective oxidation portion 26 is provided with a Ru-based selective oxidation catalyst having a spherical shape of approximately φ3 mm. (Detailed explanation about installation is omitted).

  Further, the hydrogen generator 1 includes a combustion unit 2 that serves as a heating unit for supplying reaction heat necessary for the reforming reaction in the reforming unit 20. The combustion unit 2 is a burner that burns combustion gas that serves as a heating source, a combustion detection unit 22 that is a frame rod that detects the combustion state of the combustion unit 2, and combustion air that supplies fuel air to the combustion unit 2 It has the combustion fan 18 used as a supply part. Combustion gas burned in the combustion unit 2 is supplied to the combustion unit 2 via a combustion gas supply path (not shown). The hydrogen-containing gas generated by the hydrogen generator 1 is supplied to a fuel cell or the like installed outside via the derivation unit 12. The flame rod is a device that applies a voltage to ions generated when a flame is formed and measures the value of the ionic current that flows at that time. Further, the reforming unit 20 and the preheating unit 23 are configured to be supplied from the combustion exhaust gas generated in the combustion unit 2 through the wall surface of the hydrogen generator 1 with the combustion unit 2. Further, the combustion exhaust gas is exhausted to the outside of the hydrogen generator 1 from the exhaust port 44 at the upper right of the drawing.

  The preheating unit 23 has the same side wall surface as that of the derivation unit 12 and the carbon monoxide reduction unit (the selective oxidation unit 26 and the conversion unit 25), and the hydrogen-containing gas and the selective oxidation unit flowing through the derivation unit 12 and the carbon monoxide reduction unit. 26, configured to be able to exchange heat with the catalyst provided in the shift unit 25. In particular, the derivation unit 12 is configured to exchange heat between the hydrogen-containing gas derived from the hydrogen generator 1 and the low-temperature raw material and water supplied to the hydrogen generator 1.

  A water supply unit is connected to the water supply path 3. A raw material supply unit is connected to the raw material supply path 4. The raw material supplied from the raw material supply path 4 may be a raw material containing an organic compound composed of at least carbon and hydrogen elements such as hydrocarbons, for example, city gas mainly composed of methane, natural gas, LPG, etc. is there. Here, a gas infrastructure line of city gas is used as a raw material supply source, and a desulfurization section for removing sulfur compounds, which are odorous components in the raw material, is connected to the gas infrastructure line. For example, the desulfurization part can use a zeolite-based adsorption / removal agent that adsorbs a sulfur compound, which is an odorous component in city gas. The water supply path 3 and the raw material supply path 4 can use a booster pump. For example, the water supply path 3 and the raw material supply path 4 have a function of adjusting the flow rate of water to be supplied and the flow rate of the raw material by controlling input current pulses, input power, and the like. (Details not shown).

A reforming temperature detector 27 for detecting the temperature (reaction temperature) of the reforming catalyst (or hydrogen-containing gas) in the reforming unit 20 and a temperature of the shift catalyst (or a mixed gas of raw material and steam) in the shift unit 25 are detected. A metamorphic temperature detector 24 is provided.

  Next, the operation of the hydrogen generator 1 will be described.

  When starting the hydrogen generator 1 from the stop state, the raw material is supplied to the combustion unit 2 according to a command from an operation control unit (details not shown), and the raw material is ignited by the combustion unit 2 to heat the hydrogen generator 1. To start.

  After starting heating in the combustion unit 2, the raw material is supplied to the hydrogen generator 1 (steam reforming unit 20) through the raw material supply path 4, and water is supplied from the water supply path 3 to the hydrogen generator 1. And start the reforming reaction. In the present embodiment, city gas (13A) containing methane as a main component is used as a raw material. The amount of water supplied from the water supply path 3 is controlled so that the water vapor is about 3 moles per mole of carbon atoms in the average molecular formula of the city gas (steam carbon ratio (S / C)). About 3).

  In the hydrogen generator 1, a steam reforming reaction is performed in the reforming unit 20, a modification reaction is performed in the modification unit 25, and a selective oxidation reaction of carbon monoxide is performed in the selective oxidation unit 26. The transformation unit 25 and the selective oxidation unit 26 reach a temperature suitable for the reaction, and after the carbon monoxide concentration is reduced to a predetermined concentration (in this embodiment, 20 ppm or less on a dry gas basis), hydrogen is contained through the derivation unit 12. The supply of gas to, for example, a fuel cell is started.

When the apparatus is stopped, the supply of the raw materials and water is stopped, and the temperatures of the catalyst layers of the reforming unit 20, the shift unit 25, and the selective oxidation unit 26 in the hydrogen generator 1 are lowered. At this time, the basic operation of the combustion unit 2 is stopped. After the temperature of each catalyst layer is lowered to the set temperature, the raw material is circulated through the hydrogen generator 1 and the hydrogen-containing gas staying inside the gas path is replaced with the raw material, and the hydrogen generator 1 is appropriately sealed. To perform the operation.
In the embodiment of the present invention, the reforming catalyst 21 is described as being provided with the first support plate 51 and the second support plate 52, but it goes without saying that the same applies to all the granular catalysts. .
Moreover, although the opening hole of the 1st support plate 51 and the 2nd support plate 52 assumed the elongate hole and was expressed as the short part of the elongate hole, it cannot be overemphasized that it applies not to an elongate hole but to (phi) hole. Further, the first support plate 51 can be formed of a mesh body.

  The apparatus according to the present invention, which is useful for all hydrogen generators having a granular catalyst, is industrially used as a hydrogen generator and a fuel cell power generation system that can use a catalyst having a particle size smaller than the plate thickness of the shelf. It is possible to use.

DESCRIPTION OF SYMBOLS 1 Hydrogen generator 2 Combustion part 3 Water supply path 4 Raw material supply path 5 Inner cylinder 6 Inner cylinder bottom plate 7 Middle cylinder 8 Middle cylinder bottom plate 9 Middle cylinder bottom plate through-hole 12 Outlet part 15 Outer cylinder 16 Outer cylinder bottom plate 18 Combustion fan 19 Air Supply section 20 Reforming section 21 Reforming catalyst 22 Combustion detection section 23 Preheating section 24 Transformation temperature detection section 25 Transformation section 26 Selective oxidation section 27 Reforming temperature detection section 31 Reactor 44 Discharge port 51 First support plate 52 Second support Plate 53 Projection

Claims (6)

A reaction vessel containing a granular catalyst;
A first support plate that is disposed inside the reaction vessel, has a plurality of openings, and supports the granular catalyst;
A second support plate supporting the first support plate and having a plurality of openings formed therein;
With
The first support plate is disposed on the upper side of the first support plate in the direction of gravity with a gap from the second support plate, and is thinner than the second support plate, and has an opening in the first support plate. Is configured to be smaller than the opening of the second support plate,
Hydrogen generator. The second support plate is formed with a protrusion for supporting the first support plate that is convex upward in the direction of gravity.
The hydrogen generator according to claim 1. The distance between the first support plate and the second support plate is configured to be greater than the thickness of both the first support plate and the second support plate.
The hydrogen generator according to claim 1 or 2. The hole diameter of the opening of the first support plate is configured to be smaller than the particle diameter of the catalyst.
The hydrogen generator according to any one of claims 1 to 3. The hole diameter of the opening of the second support plate is configured to be larger than the particle diameter of the catalyst.
The hydrogen generator of any one of Claims 1-4. The first support plate is disposed with a gap from the inner wall of the reaction vessel,
One end of the second support plate is fixed to the reaction vessel,
The catalyst is a reforming catalyst that generates a fuel gas containing hydrogen by reacting a raw material gas containing hydrocarbon with steam to perform reforming,
The reaction vessel is configured such that a raw material gas that reacts with the catalyst flows from the upper part to the lower part,
The hydrogen generator according to any one of claims 1 to 5.