Catalyst device

Abstract

The utility model provides a kind of catalyst device.The technical disclosed in the present specification is to solve the problem in the catalyst device for generating reaction gas from raw gas by chemical reaction accompanying endothermic reaction, the reduction of reaction efficiency caused by endothermic is inhibited.The catalyst device (1) for making raw gas chemical reaction into reaction gas has flow path (3), catalyst (10) arranged in flow path (3) and flow rate reducing member (12) arranged in flow path (3).Raw gas generates reaction gas by chemical reaction accompanying endothermic reaction.The temperature in flow path (3) is lowered due to endothermic reaction.The flow rate reducing member (12) is heat shrunk due to temperature reduction.

Description

Technical Field

[0001] This utility model relates to a catalyst device for chemically reacting raw material gases into reaction gases. Background Technology

[0002] Patent Document 1 discloses a catalyst structure that decomposes ammonia, a feed gas, to generate hydrogen, a reactant gas. Metal particles are used as the catalyst for ammonia decomposition. The catalyst structure is constructed by loading the catalyst into the interior of a porous support of a zeolite-type compound. The chemical reaction of decomposing ammonia into hydrogen and nitrogen is endothermic. The more ammonia is decomposed, the lower the decomposition efficiency becomes due to endothermic reaction. In conventional catalyst structures and catalyst devices, the catalyst needs to be heated to maintain decomposition efficiency, and the heating needs to be controlled. Therefore, there is room for improvement in catalyst devices utilizing a chemical reaction accompanied by an endothermic reaction.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2018 / 221701 Utility Model Content

[0006] Problems to be solved by utility models

[0007] The problem to be solved by the technology disclosed in this specification is to suppress the decrease in reaction efficiency caused by endothermic reaction in a catalyst device that utilizes a chemical reaction accompanied by an endothermic reaction to generate a reaction gas from a feed gas.

[0008] Solution for solving the problem

[0009] According to one technical solution of this utility model, a catalyst device for chemically reacting a raw material gas into a reactant gas includes a flow path, a catalyst disposed within the flow path, and a flow rate reduction component disposed within the flow path. The raw material gas generates the reactant gas through a chemical reaction accompanied by an endothermic reaction. The temperature within the flow path decreases due to the endothermic reaction. The flow rate reduction component thermally contracts due to the decrease in temperature.

[0010] Therefore, by heating the catalyst, the velocity reduction component disposed within the same flow path is also heated. This causes the velocity reduction component to thermally expand. As the temperature within the flow path decreases due to the endothermic reaction, the velocity reduction component thermally contracts from its expanded state. The voids within the flow path expand as the velocity reduction component thermally contracts. This expansion of the voids reduces the flow rate of the feed gas, increasing the contact time between the feed gas and the catalyst. Consequently, the reaction efficiency of the chemical reaction can be increased. Thus, by expanding the voids within the flow path, the decrease in reaction efficiency caused by endothermic reactions can be suppressed.

[0011] According to other technical solutions of this utility model, the thermal expansion coefficient of the flow rate reduction component is greater than that of the catalyst. Therefore, when the flow rate reduction component thermally contracts, the voids within the flow path can be expanded efficiently. This, in turn, more reliably suppresses the decrease in reaction efficiency caused by endothermic reactions.

[0012] According to other technical solutions of this utility model, the flow rate reducing component is granular or blocky. Therefore, the flow rate reducing component can be easily disposed in the voids between the catalysts. This allows the voids expanded during thermal contraction of the flow rate reducing component to be adjacent to the catalyst. Therefore, the reaction efficiency of the chemical reaction can be efficiently increased by expanding the voids within the flow path.

[0013] According to other technical solutions of this utility model, the flow rate reduction component is made of stainless steel or aluminum. Therefore, it is possible to make the flow rate reduction component from a material with a high coefficient of thermal expansion and low reactivity with the raw material gas and reactant gas, which is preferred as a catalyst.

[0014] According to other technical solutions of this utility model, the raw material gas is ammonia, and the flow rate reduction component is stainless steel. Therefore, the flow rate reduction component can be made of a material with a high thermal expansion coefficient and low reactivity with ammonia, hydrogen, and nitrogen. Attached Figure Description

[0015] Figure 1 This is a block diagram of a fuel cell system equipped with the catalyst device of this utility model.

[0016] Figure 2 This is a schematic longitudinal sectional view of the catalyst device of the first embodiment.

[0017] Figure 3 It is a rough longitudinal sectional view showing the catalyst layer as the temperature rises.

[0018] Figure 4 It is a rough longitudinal cross-sectional view of the catalyst layer as the temperature decreases.

[0019] Explanation of reference numerals in the attached figures

[0020] 1. Catalyst unit; 2. Shell; 3. Flow path; 3a. Feed gas inlet; 3b. Reaction gas outlet; 4. Heater; 5. Catalyst layer; 5a. Inlet; 5b. Outlet; 10. Catalyst; 10a. Average particle size; 11. Voids; 12. Flow rate reduction component; 12a. Average expansion length; 12b. Average contraction length; 20. Fuel cell system; 21. Ammonia storage tank; 22. Adsorption unit; 23. Fuel cell. Detailed Implementation

[0021] The following is based on Figures 1-4The first embodiment of the catalyst device of this utility model will be described. The same reference numerals in the description refer to the same elements having the same function, and will not be described repeatedly. For example... Figure 1 As shown, catalyst unit 1 is disposed in fuel cell system 20. Fuel cell system 20 has an ammonia storage tank 21 upstream of catalyst unit 1. Fuel cell system 20 has an adsorption unit 22 downstream of catalyst unit 1, and a fuel cell (FC) 23 is further disposed downstream.

[0022] like Figure 1 As shown, ammonia (NH3) is introduced into the catalyst unit 1 from the ammonia storage tank 21 as a feed gas. In the catalyst unit 1, ammonia is decomposed into hydrogen (H2) and nitrogen (N2), generating a reaction gas containing hydrogen and nitrogen. A mixture of the reaction gas and trace amounts of undecomposed ammonia is discharged from the catalyst unit 1 to the adsorption unit 22. The adsorption unit 22 adsorbs the ammonia contained in the mixture. The purified gas, from which ammonia has been removed from the mixture, is introduced into the fuel cell 23. The fuel cell 23 uses the hydrogen contained in the purified gas as fuel to generate electricity.

[0023] like Figure 2 As shown, the catalyst device 1 has a generally cylindrical shell 2. A flow path 3 is provided inside the shell 2. A feed gas inlet 3a, communicating with the flow path 3, is provided at the upstream end of the shell 2. Ammonia, as the feed gas, is introduced from an upstream ammonia storage tank 21 (see reference 2) via the feed gas inlet 3a. Figure 1 The catalyst is introduced into the flow path 3 of the catalyst device 1. A reaction gas outlet 3b, communicating with the flow path 3, is provided at the downstream end of the housing 2. A mixed gas containing hydrogen and nitrogen as reaction gases flows from the flow path 3 to the downstream adsorption device 22 (see reference 22) via the reaction gas outlet 3b. Figure 1 )discharge.

[0024] like Figure 2 As shown, most of the flow path 3 consists of a catalyst layer 5 with a roughly constant cross-sectional area orthogonal to the flow direction. The cross-sectional area of ​​the catalyst layer 5 is roughly constant from the upstream inlet 5a to the downstream outlet 5b. A heater 4 is disposed on the radially outer side of the housing 2. The heater 4 heats the catalyst layer 5 to approximately the same degree. The radially outer periphery of the heater 4 is covered with an insulating material (not shown).

[0025] like Figure 2As shown, a plurality of catalysts 10 and a plurality of flow rate reducing members 12 are housed in the catalyst layer 5. The catalysts 10 are generally spherical granules or blocks. The flow rate reducing members 12 are, for example, generally spherical, columnar, rod-shaped, plate-shaped granules or blocks. In this invention, a generally cylindrical flow rate reducing member 12 is exemplified. The plurality of catalysts 10 and the plurality of flow rate reducing members 12 are generally uniformly mixed within the catalyst layer 5. Voids 11 are formed between the plurality of catalysts 10, or between the plurality of flow rate reducing members 12, or between the catalysts 10 and the flow rate reducing members 12. Figure 3 As shown, the plurality of catalysts 10 have an average particle size 10a and are configured to be substantially the same size and substantially the same shape. The average of the maximum lengths of the plurality of flow rate reducing members 12 after expansion when heated by the heater is the average expansion length 12a. The plurality of flow rate reducing members 12 are configured to be substantially the same size and substantially the same shape. In addition, the size, number, and packing density of the catalysts 10 and flow rate reducing members 12 in the figure are shown in a simplified manner for ease of explanation and specific values ​​are not specified. Therefore, the size ratio of the catalysts 10 and flow rate reducing members 12 to the shell 2 is not specified, nor is the mixing ratio of the plurality of catalysts 10 and the plurality of flow rate reducing members 12 specifically specified.

[0026] like Figure 2 , Figure 3 As shown, catalyst 10 is formed by mixing and sintering metal particles, which function as catalysts themselves, with a support. Metal particles are loaded onto the surface of catalyst 10. The material of the metal particles can be, for example, at least one of ruthenium, nickel, cobalt, and palladium, but is not limited to these; other metals, alloys, etc., can also be used.

[0027] like Figure 2 , Figure 3 As shown, the flow rate reduction member 12 is formed of a material with a high coefficient of thermal expansion (linear expansion). More preferably, the material of the flow rate reduction member 12 is a material with low reactivity to ammonia as the feed gas and hydrogen and nitrogen as the reactant gases, and is difficult to corrode. For example, a material with a coefficient of linear expansion of 18 [×10] is preferred for the flow rate reduction member 12. -6 Stainless steel (SUS) with a coefficient of linear expansion of 26 [×10] K] -6 The material of the flow rate reducing member 12 may be aluminum, or more preferably stainless steel. The material of the flow rate reducing member 12 may also be a material with a coefficient of linear expansion that is the same as or higher than that of stainless steel, such as magnesium, zinc or other metallic materials or alloys such as brass or duralumin.

[0028] like Figure 3 As shown, the flow rate reduction component 12 is supplied by the heater 4 (refer to...) Figure 2Heating causes the average length along its longitudinal direction to expand to an average expansion length of 12a. When the flow rate reduction component 12 is made of stainless steel, the expansion per 1cm at a temperature increase of 100°C... 3 The volume increase is approximately 5.4 mm. 3 When the flow rate reduction component 12 is made of aluminum, the flow rate per 1cm increases by 100°C. 3 The volume increase is approximately 7.8 mm. 3 On the other hand, the thermal expansion coefficient of the catalyst 10 is a sufficiently small positive or negative value relative to the flow rate reduction member 12. For example, the linear expansion coefficient of the catalyst 10 is less than 20%, less than 10%, or less than 5% of that of the flow rate reduction member 12. Therefore, the volume increase of the catalyst 10 relative to the temperature increase is negligible, or it shrinks slightly with the temperature increase. Therefore, the average particle size 10a of the catalyst 10 is approximately constant when not heated, when heated, and when the temperature decreases due to the endothermic reaction as described later.

[0029] like Figure 3 As shown, when the flow rate decreases, component 12 is affected by heater 4 (refer to...). Figure 2 When the catalyst 10 is heated and thermally expands, the void 11 around the flow rate reducing member 12 narrows by an amount corresponding to the volume of thermal expansion. On the other hand, the catalyst 10 maintains a substantially constant volume even when heated by the heater 4. Therefore, the reduction of the void 11 occurs around the flow rate reducing member 12. As the void 11 around the flow rate reducing member 12 narrows, the flow rate of the gas in the flow path 3 increases. Therefore, the contact time between the feed gas and the catalyst 10 is reduced. Since the efficiency of the chemical reaction is increased by heating the catalyst 10, even though the flow rate of the feed gas increases and the contact time with the catalyst 10 is reduced, the feed gas can still undergo a sufficient chemical reaction to generate a reactant gas.

[0030] The chemical reaction that decomposes ammonia into hydrogen and nitrogen is an endothermic reaction. Therefore, as... Figure 4 As shown, the more ammonia is decomposed, the more heat is absorbed in flow path 3 due to the endothermic reaction. Therefore, with heater 4 (refer to...) Figure 2 Compared to the initial heating, the temperature within flow path 3 decreases. The average length of the flow rate reduction member 12 in its longitudinal direction thermally shrinks to an average shrinkage length 12b. The voids 11 surrounding the flow rate reduction member 12 expand by an amount corresponding to the volume shrinkage. On the other hand, the catalyst 10 maintains a substantially constant volume even when the temperature drops due to the endothermic reaction. Therefore, the increase in voids 11 occurs around the flow rate reduction member 12.

[0031] like Figure 4As shown, the gas velocity within the flow path 3 decreases due to the expansion of the void 11 surrounding the velocity-reducing member 12. Consequently, the contact time between the feed gas and the catalyst 10 increases. Because the contact time between the feed gas and the catalyst 10 increases due to the reduced flow velocity, the decrease in reaction efficiency caused by the temperature drop can be suppressed. Therefore, the feed gas can undergo a sufficient chemical reaction, and the efficiency of reactant gas generation can be maintained.

[0032] As mentioned above, such as Figure 2 , Figure 4 As shown, the catalyst device 1, which chemically reacts a raw material gas into a reactant gas, includes a flow path 3, a catalyst 10 disposed within the flow path 3, and a flow rate reduction member 12 disposed within the flow path 3. The raw material gas generates the reactant gas through a chemical reaction accompanied by an endothermic reaction. Due to the endothermic reaction, the temperature within the flow path 3 decreases. The flow rate reduction member 12 thermally contracts due to the decrease in temperature.

[0033] Therefore, by heating the catalyst 10, the flow rate reduction member 12 disposed within the same flow path 3 is also heated. As a result, the flow rate reduction member 12 thermally expands. When the temperature within the flow path 3 decreases due to the endothermic reaction, the flow rate reduction member 12 thermally contracts from its expanded state. The void 11 within the flow path 3 expands as the flow rate reduction member 12 thermally contracts. With the expansion of the void 11 within the flow path 3, the flow rate of the feed gas decreases, and the contact time between the feed gas and the catalyst 10 increases. This allows the reaction efficiency of the chemical reaction to increase. Thus, by expanding the void 11 within the flow path 3, the decrease in reaction efficiency caused by endothermic reaction can be suppressed.

[0034] like Figure 4 As shown, the thermal expansion coefficient of the flow rate reducing member 12 is greater than that of the catalyst 10. Therefore, when the flow rate reducing member 12 thermally contracts, the voids 11 within the flow path 3 can be expanded efficiently. Consequently, the reduction in reaction efficiency of the chemical reaction caused by endothermic reaction can be suppressed more reliably.

[0035] like Figures 2-4 As shown, the flow rate reducing member 12 is granular or blocky. Therefore, the flow rate reducing member 12 can be easily disposed in the gaps 11 between the catalysts 10. Thus, the gaps 11 that expand when the flow rate reducing member 12 is thermally contracted can be adjacent to the catalyst 10. Therefore, the reaction efficiency of the chemical reaction can be increased efficiently by expanding the gaps 11 within the flow path 3.

[0036] like Figures 2-4 As shown, the flow rate reduction member 12 is made of stainless steel or aluminum. Therefore, the flow rate reduction member 12 can be made of a material with a high coefficient of thermal expansion and low reactivity with the raw material gas and the reactant gas, which is preferred for use as the catalyst 10.

[0037] like Figures 2-4 As shown, the feed gas is ammonia, and the flow rate reduction component 12 is made of stainless steel. Therefore, the flow rate reduction component 12 can be made of a material with a high thermal expansion coefficient and low reactivity with ammonia, hydrogen, and nitrogen.

[0038] The technology disclosed in this specification is not limited to the embodiments described above, and various modifications are possible. An example is a catalyst apparatus for the decomposition of ammonia. However, it is not limited to this; it can be applied to all catalyst apparatuses utilizing chemical reactions accompanied by endothermic reactions.

[0039] An example is shown of a catalyst 10 in which metal particles or the like are mixed with a support and the metal particles or the like are exposed on the surface. Alternatively, for example, metal particles or the like may be coated onto the surface of the support. For example, the metal that functions as the catalyst body may be formed into particulate form and used as the catalyst. The material, shape, size, etc., of the catalyst 10 are not limited to those shown and may be appropriately changed. For example, the shape of the catalyst 10 may be set to non-spherical, and for example, it may be set to a structure in which the catalyst 10 is set to a porous, non-particulate form, and a flow rate reducing member 12 is disposed within the catalyst 10. In the case where the catalyst is non-spherical, the "particle size" may be replaced, for example, with the maximum length of the particulate catalyst, or the average of the maximum length and the minimum length, etc.

[0040] The material, shape, and size of the flow rate reducing member 12 are not limited to those illustrated and can be appropriately modified. For example, the flow rate reducing member 12 can be appropriately modified to be made of a material with a linear expansion coefficient greater than that of the catalyst 10, and it is more preferable to use a material with low reactivity with the feed gas and reactant gas. For example, a cylindrical flow rate reducing member 12 is illustrated, but it can also be made into a generally spherical, prismatic, rod-shaped, plate-shaped, etc. For example, the flow rate reducing member 12 can also be made into an elongated shape with a longer maximum length, and a structure that results in a large amount of thermal contraction in the length direction when the temperature drops. For example, it can also be made into a shape and size that allows it to be adjacent to more catalysts 10.

[0041] The ratio of the number and volume of catalyst 10 to flow rate reduction members 12 within the catalyst layer 5 can be appropriately varied. Increasing the ratio of catalyst 10 can improve the generation efficiency of the reactant gas. Increasing the ratio of flow rate reduction members 12 can further suppress the decrease in reaction efficiency as the temperature decreases. The distribution of catalyst 10 and flow rate reduction members 12 within the catalyst layer 5 can, for example, be uniform. For example, the distribution can be varied by placing catalyst 10 on the radially outer portion of the catalyst layer 5 and flow rate reduction members 12 on the radially inner portion of the catalyst layer 5.

[0042] An example is shown where the catalyst 10 and the flow rate reduction member 12 are separately arranged. Alternatively, the catalyst 10 and the flow rate reduction member 12 can be arranged as a single granular or block shape. For example, the catalyst 10 can also serve as the flow rate reduction member 12. That is, the catalyst 10 and the flow rate reduction member 12 can also be made of a material that functions as a catalyst and has a high coefficient of thermal expansion, such as aluminum.

Claims

1. A catalyst device that chemically reacts a feed gas into a reactant gas, characterized in that, The catalyst device has the following features: flow path; Catalyst, which is disposed within the flow path; and A flow rate reduction component is disposed within the flow path. The raw material gas generates the reaction gas through a chemical reaction accompanied by an endothermic reaction. The temperature in the flow path decreases due to the endothermic reaction, and the flow rate reduction component thermally shrinks due to the temperature decrease.

2. The catalyst device according to claim 1, characterized in that, The thermal expansion coefficient of the flow rate reduction component is greater than that of the catalyst.

3. The catalyst device according to claim 2, characterized in that, The flow rate reduction component is granular or blocky.

4. The catalyst device according to any one of claims 1 to 3, characterized in that, The flow rate reduction component is made of stainless steel or aluminum.

5. The catalyst device according to claim 4, characterized in that, The raw material gas is ammonia, and the flow rate reduction component is made of stainless steel.

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