JP4223852B2 - Chemical reactor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chemical reaction apparatus for generating hydrogen.
[0002]
[Prior art]
Since a fuel cell is a device that generates electric energy by reacting hydrogen and oxygen, supply of hydrogen and oxygen is essential. Although oxygen can be obtained from the atmosphere (air), hydrogen requires a hydrogen generation plant facility on a large scale and a small hydrogen generator called a reformer on a small scale.
[0003]
The small hydrogen generator is suitable for equipment that is difficult to equip with a hydrogen cylinder such as a portable generator. As such a hydrogen generator, one that controls the temperature by water cooling is known (for example, see Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-172003 (page 5-7, FIG. 3)
[0005]
FIG. 3 of Patent Document 1 will be described with reference to FIG. 4 below.
FIG. 4 is a cross-sectional view of a conventional hydrogen generator. However, the code was re-assigned.
Reference numeral 101 denotes a reforming reaction section, which generates a hydrogen-rich reformed gas from a raw material gas by a reaction including a partial oxidation reaction (see the first and second lines from the bottom of paragraph number [0031] of the above publication).
[0006]
Reference numeral 102 denotes a shift reaction unit that reduces the CO concentration in the reformed gas by a water gas shift reaction (see paragraph number [0032] lines 3 and 4 of the above publication).
Reference numeral 103 denotes a CO selective oxidation reaction unit, which further reduces the CO concentration by a CO selective oxidation reaction (see paragraph number [0032] lines 7 and 8 of the above publication).
[0007]
104 and 104 are water supply pipes for supplying water, 105 is a fluid flow path serving as a water passage, 106 is a water return pipe serving as a water outlet, and the shift reaction unit 102 and the CO selective oxidation reaction unit 103 are water Cool forcibly with.
[0008]
As is well known, since the reforming reaction proceeds at about 700 ° C., the reforming reaction section 101 needs to be kept at a high temperature. In contrast, the shift reaction varies depending on the type of catalyst, but the reaction proceeds at around 350 ° C., and the CO selective oxidation reaction proceeds at 200 ° C. Therefore, it is the reformer 108 of the above publication that controls the temperature of the shift reaction unit 102 and the CO selective oxidation reaction unit 103 by water cooling.
[0009]
[Problems to be solved by the invention]
In order to provide the fluid flow path 105, the wall thickness of the cylindrical container 107 must be increased, and the reformer 108 becomes large and heavy. This makes it difficult to downsize the equipment, and there is a problem in terms of portability.
[0010]
In addition, since the cooling water is circulated, it is difficult to lower the temperature of the cooling water, and it is not easy to lower the shift reaction unit 102 and the CO selective oxidation reaction unit 103 to a desired temperature.
[0011]
For example, if the amount of water circulation is increased or a cooling device using a refrigerant or the like is provided in the water circulation path, the temperature of the cooling water can be greatly reduced. It becomes difficult.
[0012]
If the fluid flow path 105 is provided on the wall of the vessel 107 and indirectly cooled, the temperature of the shift reaction unit 102 and the CO selective oxidation reaction unit 103 can be efficiently lowered if the cooling can be performed more directly. In particular, the hydrogen generation efficiency of the portable small-sized hydrogen generator increases, which can contribute to downsizing.
[0013]
Further, the shift reaction unit 102 and the CO selective oxidation reaction unit 103 are provided with a plurality of heat recovery units made of a honeycomb body or heat transfer fins for recovering heat from the reformed gas in the middle of the reformed gas flow. The cooling structure becomes complicated and the cost increases.
[0014]
Therefore, an object of the present invention is to improve the chemical reaction apparatus, to efficiently reduce the temperature of the CO conversion catalyst for reducing CO, to reduce the weight and size of the chemical reaction apparatus, and to simplify the cooling structure. The purpose is to reduce the cost of the chemical reaction apparatus.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, according to a first aspect of the present invention, a reforming catalyst and a CO shift catalyst are housed in series in this order in a cylindrical container, and a raw material gas composed of hydrocarbon or aliphatic alcohol is combined with hydrogen by the reforming catalyst. A chemical reaction device that reforms a mixed gas of carbon oxide and carbon dioxide and converts the mixed gas with a CO conversion catalyst to reduce the concentration of carbon monoxide and generate hydrogen. A heat storage body that stores the retained heat of the mixed gas is disposed between the CO conversion catalyst and the front end of a water supply pipe that supplies water from the outside faces the heat storage body.
[0016]
A heat accumulator is arranged between the reforming catalyst and the CO conversion catalyst in the cylindrical container, the tip of the water supply pipe is faced to the heat accumulator, and the heat stored in the mixed gas is stored in the hot water accumulator. By supplying water through the supply pipe, the mixed gas is directly cooled by the heat of vaporization of water, so the temperature of the CO conversion catalyst can be efficiently reduced, and the CO conversion catalyst is controlled to a temperature suitable for the reaction. be able to.
[0017]
Since the water supply pipe only needs to be able to supply water to the heat storage body, there is no need to provide the water supply pipe in the peripheral wall of the cylindrical container, and it is possible to suppress the increase in the size and weight of the chemical reaction device. The apparatus can be made compact.
[0018]
Furthermore, by configuring the cooling device with the heat storage body and the water supply pipe, the cooling device is simplified, and the cost of the chemical reaction device can be reduced.
[0019]
According to a second aspect of the present invention, the heat storage body has gas permeability.
By having gas permeability in the heat storage body, heat exchange between the mixed gas that passes through the heat storage body and the heat storage body can be further promoted.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a cross-sectional view of a chemical reaction apparatus according to the present invention. A hydrogen generation apparatus 10 as a chemical reaction apparatus includes a cylindrical container 11, a gas inlet 13 attached to an upper end plate 12 of the cylindrical container 11, The gas outlet 15 attached to the lower end plate 14 of the cylindrical container 11, the reforming catalyst 16 fitted to the upper part in the cylindrical container 11, and the cylindrical container 11 are fitted so as to be positioned below the reforming catalyst 16. The heat storage body 17, the CO conversion catalyst 18 below the heat storage body 17 and fitted to the lower end plate 14 from the middle stage in the cylindrical container 11, the CO removal catalyst 19 thereunder, and the cylindrical container 11 A heat insulating material 21 that covers the entire outer surface, and a water supply pipe 22 having a tip inserted into the heat storage body 17 through the heat insulating material 21, the CO removal catalyst 19, and the CO shift catalyst 18 in order to supply water from outside. The upper end plate 12 and the reforming catalyst 16 Between the gas dispersion chamber 23, the upper space 24 between the reforming catalyst 16 and the heat storage body 17, the lower space 25 between the heat storage body 17 and the CO conversion catalyst 18, the CO conversion catalyst 18 and the CO removal catalyst 19. A structural feature is that the lowermost space 27 is formed between the metamorphic space 26 and the CO removal catalyst 19 and the lower end plate 14 therebetween.
The heat storage body 17 and the water supply pipe 22 constitute a cooling device 28.
[0021]
Although the cylindrical container 11 is basically a cylindrical container, it may be a rectangular cylinder container such as a square, pentagon, hexagon, or octagon, or an elliptical cylinder container.
[0022]
In the gas dispersion chamber 23, lashing (particles, wire mesh, etc.) is packed or interposed in order to prevent the gas flow from being biased. This allows the gas to flow evenly from top to bottom. However, the illustration of lashing was omitted from the figure.
[0023]
The cylindrical container 11 is a corrosion-resistant and heat-resistant sealed container made of, for example, a stainless steel plate (SUS316) having an inner diameter of 50 mm and a plate thickness of 2 mm, which is closed by the upper end plate 12 and the lower end plate 14 made of the same material.
The reforming catalyst 16 is preferably a ruthenium-based catalyst.
[0024]
The heat storage body 17 is a material that is permeable and has low pressure loss of the permeated mixed gas, heat resistance, no reactivity with the mixed gas and water, a large heat capacity, and good heat conduction.
[0025]
The CO shift catalyst 18 is suitably a copper-zinc (Cu—Zn) based catalyst.
The CO removal catalyst 19 is preferably a ruthenium catalyst.
The water supply pipe 22 is made of stainless steel (SUS316), and flows water sent by a pump from a water tank (not shown) to the heat storage body 17.
[0026]
FIG. 2 is a principle explanatory view showing the principle of the hydrogen generator according to the present invention.
First, when isobutane, water, and air are supplied from the gas inlet to the hydrogen generator, a combined reforming reaction such as Formula (1) and Formula (2) proceeds in the reforming catalyst.
[0027]
In both formulas (1) and ( ₂ ), O _{2 in} the third term on the left side causes a partial oxidation reaction with C ₄ H _{10 in} the first term on the left side. This reaction is an exothermic reaction.
On the other hand, H ₂ O in the second term on the left side causes a steam reforming reaction with C ₄ H _{10 in} the first term on the left side. This reaction is an endothermic reaction that requires heat to be applied from the outside.
[0028]
Since a reforming catalyst performs both a partial oxidation reaction and a steam reforming reaction, such a reforming method is called a “combined reforming reaction”.
As is apparent from the right side of the equations (1) and (2), this combined reforming reaction produces a mixed gas, that is, H ₂ , CO _2, and CO as the reformed gas. In addition, CH ₄ is generated. This reforming reaction proceeds at about 700 ° C.
[0029]
The heat storage body is a member that becomes high temperature when the high-temperature reformed gas obtained by the reforming reaction by the reforming catalyst permeates. By supplying water from the outside to the heat storage body through a water supply pipe, By contacting the high-temperature reformed gas or the heat storage body, heat is removed from the heat storage body and the mixed gas that permeates the heat storage body by the heat of vaporization when water evaporates, and the temperature of the mixed gas is lowered, that is, cooled.
[0030]
The reformed gas whose temperature has decreased reaches the CO shift catalyst, and the CO shift reaction proceeds in the CO in the reformed gas. That is, in the CO conversion catalyst, wherein ▲ 3 by contacting the residual water vapor (H 2 _O), the remaining CO as shown in ▼, about 90% of the CO in the reformed gas generated by the reforming catalyst H ₂ And CO ₂ . This CO shift reaction (also referred to as “CO shift reaction”) proceeds at 200 to 400 ° C. The heat resistance temperature of the CO shift catalyst is 400 ° C. or less, and the temperature of the above-described CO shift reaction is also determined from this point.
Thus, the present invention employs a cooling structure in which the temperature of the reformed gas is lowered from 700 ° C. to 400 ° C. or less by evaporating water with the heat storage body.
[0031]
In the above-mentioned CO shift reaction, the CO concentration decreases to 1%, but CO cannot be supplied to the fuel cell as it is because it is a harmful gas for the catalyst of the fuel cell. Therefore, the reaction of the formula (4) is further caused by the CO removal catalyst to reduce the CO concentration to about 10 ppm. This CO removal reaction (also referred to as “CO selective oxidation reaction”) proceeds at about 200 ° C.
[0032]
FIGS. 3A and 3B are experimental apparatus diagrams showing the effects of the reformed gas cooling apparatus, and FIG. 3A is an experimental apparatus diagram according to the first embodiment (first embodiment) of the present invention. (B) is an experimental apparatus diagram according to a comparative example, the comparative example of (b) is different in that it does not include the cooling device provided in the first embodiment of (a), the other is the same .
[0033]
(1) Common experimental conditions:
Material of the cylindrical container 11: SUS316
Size of cylindrical container 11: inner diameter 50 mm × thickness 2 mm × length 200 mm
Height H1 of gas dispersion chamber 22: 20 mm
Lashing material in the gas dispersion chamber 22: an alumina cylinder having an outer diameter of 3 mm, an inner diameter of 1.5 mm, and a length of 3 mm.
Reforming catalyst 16 height H2: 30 mm
CO conversion catalyst 18 height H6: 80 mm
Height H7 from the lower end plate 14 to the lower surface of the CO conversion catalyst 18: 40 mm
The thickness TH of the heat insulating material 21: 10 mm
[0035]
Type of reforming catalyst 16: Ruthenium-based catalyst CO conversion catalyst 18: Cu-Zn-based catalyst CO removal catalyst 19: Ruthenium-based catalyst
First, the experiment of Example 1 was performed.
(2) Experimental conditions specific to Example 1 Experimental apparatus: FIG. 3 (a)
Height H3 of the upper space 24: 5 mm
Heat storage body: Laminated mesh of SUS316 mesh 30 Height H4 of heat storage body 17: 20 mm
Lower space 25 height H5: 5 mm
Raw materials having the following compositions and amounts were supplied from the gas inlet 13.
[0037]
-Composition and amount of raw material Isobutane: 500 cc / min (gas)
Water: 3cc / min (liquid)
Air: 4000cc / min (gas)
[0038]
The composition of the reformed gas by the above reforming catalyst and the amount of each composition were as follows. -Composition and amount of reformed gas Hydrogen: 3540 cc / min
Carbon monoxide: 950cc / min
Carbon dioxide: 950cc / min
Isobutane: 20cc / min
Methane: 20cc / min
Nitrogen: 3170 cc / min
Water vapor: 2550cc / min
[0039]
Then, the reformed gas was cooled by the cooling device 28, that is, it was allowed to pass through the heat storage body 17 and cooled by supplying water from the water supply pipe 22 into the heat storage body 17 at 2 cc / min.
Thereafter, the reformed gas was reacted with the CO shift catalyst 18 and the CO removal catalyst 19 to obtain the following product gas from the gas outlet 15.
[0040]
-Composition and amount of generated gas Hydrogen: 4420 cc / min
Carbon monoxide: 70cc / min
Carbon dioxide: 1830cc / min
Isobutane: 20cc / min
Methane: 20cc / min
Nitrogen: 3170 cc / min
Water vapor: 4160cc / min
[0041]
And after hydrogen generation was stabilized, when the temperature of several places of the hydrogen generator 10 was measured, the temperature of the measurement point shown to Fig.3 (a) was as showing below.
Measurement point T1 (center of the reforming catalyst 16): 700 ° C.
Measurement point T2 (center of the heat storage body 17): 420 ° C. (The supply of water was started after the temperature of the measurement point T2 rose to 500 ° C.)
Measurement point T3 (above the CO shift catalyst 18): 400 ° C
Measurement point T4 (below CO conversion catalyst 18): 250 ° C.
[0042]
Next, an experiment of a comparative example was performed.
(3) Experimental conditions specific to the comparative example Experimental apparatus: FIG. 3 (b)
Presence or absence of cooling device: None Space 111 height H8: 30 mm
[0043]
Raw materials having the following compositions and amounts were supplied from the gas inlet 13.
-Composition and amount of raw material Isobutane: 500 cc / min (gas)
Water: 3cc / min (liquid)
Air: 4000cc / min (gas)
[0044]
And it was made to react with a reforming catalyst, a CO shift catalyst, and a CO removal catalyst, respectively, and the following product gas was obtained from the gas outlet 15.
-Composition and amount of generated gas Hydrogen: 3990cc / min
Carbon monoxide: 500cc / min
Carbon dioxide: 1400cc / min
Isobutane: 20cc / min
Methane: 20cc / min
Nitrogen: 3170 cc / min
Water vapor: 2100cc / min
[0045]
And after hydrogen generation was stabilized, when the temperature of several places of the hydrogen generator 112 was measured, the temperature of the measurement point shown in FIG.3 (b) was as showing below.
Measurement point T11 (center of the reforming catalyst 16): 700 ° C.
Measurement point T13 (above the CO shift catalyst 18): 630 ° C.
Measurement point T14 (below the CO shift catalyst 18): 500 ° C.
[0046]
In this comparative example, since there was no cooling device, the temperature of the reformed gas reformed by the reforming catalyst could not be greatly reduced, and the temperature at the measurement point T13 greatly exceeded 400 ° C. Since the CO conversion catalyst 18 exhibits its function at around 400 ° C., it does not function sufficiently at 630 ° C. For this reason, the CO shift reaction is not promoted so much, and as a result, it is considered that a considerable amount of CO has come out from the gas outlet.
[0047]
Next, an experiment of Example 2 (second embodiment) was performed.
The experimental conditions were the same as Example 1 shown in FIG. 3A except that the heat storage body 17 was changed to a porous metal made of SUS316.
Porous metal is, for example, a sintered metal obtained by compressing and molding metal powder and then bonding the powder together, and has better thermal conductivity than the heat storage body in which the metal mesh of Example 1 is laminated. The heat exchange efficiency with the mixed gas can be further improved.
[0048]
Using the porous metal as a heat accumulator, the raw material of Example 1 is supplied to the hydrogen generator, and reacted with the reforming catalyst 16, the CO shift catalyst 18 and the CO removal catalyst 19, respectively. Obtained.
[0049]
-Composition and amount of generated gas Hydrogen: 4460 cc / min
Carbon monoxide: 40cc / min
Carbon dioxide: 1860cc / min
Isobutane: 20cc / min
Methane: 20cc / min
Nitrogen: 3170 cc / min
Water vapor: 4120cc / min
[0050]
And after hydrogen generation was stabilized, when the temperature of several places of a hydrogen generator was measured, the temperature of the measurement point was as showing below.
Measurement point T1 (center of the reforming catalyst): 700 ° C
Measurement point T2 (center of the heat storage body): 400 ° C. (The supply of water was started after the temperature of the measurement point T2 rose to 500 ° C.)
Measurement point T3 (above the CO shift catalyst): 380 ° C.
Measurement point T4 (lower part of CO shift catalyst): 200 ° C.
[0051]
In Example 2 described above, the temperature of the upper part of the CO shift catalyst became 400 ° C. or lower, the CO shift reaction proceeded smoothly, and CO reduction could be promoted.
[0052]
As described above with reference to FIG. 1, the present invention firstly stores a reforming catalyst 16, a CO shift catalyst 18 and a CO removal catalyst 19 in this order in a cylindrical container 11, in order, hydrocarbon or aliphatic. The raw material gas composed of alcohol is reformed by the reforming catalyst 16 into a mixed gas of hydrogen, carbon monoxide and carbon dioxide, and the mixed gas is subjected to a modification treatment by the CO shift catalyst 18 to reduce the carbon monoxide concentration. Further, the hydrogen generation device 10 generates hydrogen while reducing the carbon monoxide concentration to a low level by the CO removal catalyst 19, and the retained heat of the mixed gas is generated between the reforming catalyst 16 and the CO conversion catalyst 18. The heat storage body 17 to store is arrange | positioned, and the front-end | tip of the water supply pipe | tube 22 which supplies water to this heat storage body 17 from the outside was made to face.
[0053]
A heat accumulator 17 is disposed between the reforming catalyst 16 and the CO conversion catalyst 18 in the cylindrical container 11, the tip of the water supply pipe 22 faces the heat accumulator 17, and the stored heat of the mixed gas is stored to a high temperature. In the present invention, water is supplied to the heat storage body 17 through the water supply pipe 22 so that the CO concentration reducing portion is cooled indirectly with water that has flowed into the wall. Since the mixed gas, the CO shift catalyst 18 and the CO removal catalyst 19 are directly cooled by the heat of vaporization, the temperature of the mixed gas, the CO shift catalyst 18 and the CO removal catalyst 19 can be efficiently reduced, and the CO shift catalyst 18 and the CO removal catalyst 19 can be controlled to a temperature suitable for the reaction.
[0054]
Since the water supply pipe 22 only needs to be able to supply water to the heat storage body 17, the pipe of the water supply pipe 22 does not need to be provided in the peripheral wall of the cylindrical container 11, and the increase in size and weight of the hydrogen generator 10 is suppressed. Thus, the hydrogen generator 10 can be made compact.
[0055]
Further, since the heat storage body 17 and the water supply pipe 22 constitute the cooling device 28, the cooling device 28 is simplified, and the cost of the hydrogen generator 10 can be reduced.
[0056]
Second, the present invention is characterized in that the heat storage body 17 has gas permeability.
By having gas permeability in the heat storage body 17, heat exchange between the mixed gas that passes through the heat storage body 17 and the heat storage body 17 can be further promoted.
[0057]
In addition to the stainless steel wire mesh and stainless steel porous metal, the heat storage body of the present invention includes a metal wire mesh laminate other than stainless steel, a porous ceramic (porous ceramic), a metal fiber molded body, and a ceramic. A fiber molded body or a plurality of granular metals or ceramics stored in a container having air permeability may be used.
[0058]
Moreover, although the CO removal catalyst shown in the embodiment is disposed in the hydrogen generator, the present invention is not limited thereto, and may be provided outside the hydrogen generator. In that case, the size of the hydrogen generator can be reduced, and the degree of freedom of installation is increased.
[0059]
【The invention's effect】
The present invention exhibits the following effects by the above configuration.
In the chemical reaction device according to claim 1, a heat storage body that stores the retained heat of the mixed gas is disposed between the reforming catalyst and the CO conversion catalyst, and a tip of a water supply pipe that supplies water from the outside to the heat storage body is provided. Because it was exposed, by supplying water to the heat storage body that has become a high temperature by storing the retained heat of the mixed gas, the mixed gas and the CO conversion catalyst are directly cooled by the heat of vaporization of water, The temperature of the CO shift catalyst can be efficiently reduced, and the CO shift catalyst can be controlled to a temperature suitable for the reaction. Therefore, hydrogen can be produced efficiently.
[0060]
Since the water supply pipe only needs to be able to supply water to the heat storage body, the pipe of the water supply pipe does not need to be particularly provided in the peripheral wall of the cylindrical container, and the chemical reaction device can be prevented from increasing in size and weight. The apparatus can be made compact.
Furthermore, by configuring the cooling device with the heat storage body and the water supply pipe, the cooling device is simplified, and the cost of the chemical reaction device can be reduced.
[0061]
In the chemical reaction device according to the second aspect, since the heat storage body has gas permeability, the heat exchange between the mixed gas that passes through the heat storage body and the heat storage body can be further promoted.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a chemical reaction apparatus according to the present invention. FIG. 2 is a principle explanatory view showing the principle of a hydrogen generation apparatus according to the present invention. Fig. 4 Cross-sectional view of a conventional hydrogen generator [Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Chemical reaction apparatus (hydrogen generator), 16 ... Reforming catalyst, 17 ... Heat storage body, 18 ... CO conversion catalyst, 22 ... Water supply pipe | tube.

Claims (2)

A reforming catalyst and a CO shift catalyst are housed in series in this order in a cylindrical container, and the raw material gas consisting of hydrocarbon or aliphatic alcohol is changed to a mixed gas of hydrogen, carbon monoxide and carbon dioxide by the reforming catalyst. A chemical reaction device for generating hydrogen by reducing the carbon monoxide concentration by converting the mixed gas with the CO conversion catalyst.
A heat storage body that stores the retained heat of the mixed gas is disposed between the reforming catalyst and the CO conversion catalyst, and a tip of a water supply pipe that supplies water from the outside to the heat storage body is faced. A chemical reaction device. The chemical reaction device according to claim 1, wherein the heat storage body has gas permeability.

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