Carburizing gas generation apparatus

Abstract

To provide a carburizing gas generation apparatus.SOLUTION: A carburizing gas generation apparatus according to the present invention comprises a combustion section including a first gas supply path for supplying a hydrocarbon-based gas serving as a raw material, a second gas supply path for supplying a combustion-supporting gas, and a combustion chamber that incompletely combusts the hydrocarbon-based gas and the combustion-supporting gas to generate combustion gas; a dilution section located on a secondary side of the combustion section; and a catalyst section located on a secondary side of the dilution section and including a catalyst, where the catalyst section includes a catalyst housing tube that houses the catalyst and includes an expandable and contractible portion extendable and contractible in a direction in which the combustion section and the dilution section are arranged, and in the catalyst section, the combustion gas that has passed through the dilution section is reacted with the heated catalyst to generate a carburizing gas containing carbon monoxide gas and hydrogen gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a carburizing gas generator. [Background technology]

[0002] The applicant of the present application has been conducting various technological developments relating to a small-sized, energy-efficient carburizing gas generator. The following Patent Documents 1 and 2 propose a structure for a carburizing gas generator in which a carburizing gas generator having a combustion section, a reforming section, a dilution section, and a furnace connection section is connected to the top of the furnace body, and a catalyst layer is provided at the furnace connection section. In this furnace connection section, a refractory material is packed inside a metal tube, and a flow path is formed within the refractory material, so that the gas flowing through the flow path passes through the catalyst layer.

[0003] Also, as described in Patent Document 3 below, a hydrocarbon gas reformer is known in which a heat insulating space is provided between an inner cylinder and an outer case, a catalyst is housed in the inner cylinder, and a gap is provided between the outlet of the outer case and the outlet of the inner cylinder. This device employs a configuration in which a support cylinder is provided inside the outlet of the outer case, and the support cylinder is inserted into the outlet of the inner cylinder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7451608 [Patent Document 2] Patent No. 7453281 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-206383 Summary of the Invention [Problem to be solved by the invention]

[0005] In the carburizing gas generators described in Patent Documents 1 and 2, when the catalyst is heated using exhaust heat from an electric heater or carburizing furnace, the catalyst must be placed inside a metal tube and the metal tube must be heated directly with the exhaust heat from the electric heater or carburizing furnace. When the metal tube is heated, the metal tube containing the catalyst expands and contracts due to the thermal expansion of the metal. In particular, in a configuration in which the carburizing gas generator is installed above the furnace body, the catalyst section is constrained by the furnace body and the dilution section. When the catalyst is heated using exhaust heat from the electric heater or carburizing furnace, the catalyst tower made of a metal tube expands, which can lead to metal fatigue. Furthermore, in the reformer described in Patent Document 3, the inner cylinder that houses the catalyst and the outer case are not fixed to each other and have a gap between them, so there is no problem even if the inner cylinder is heated and expands downward. However, when the inner cylinder is heated, the outer case is inevitably heated and expands. In the configuration described in Patent Document 3, a heat exchanger is incorporated into the piping at the outlet of the outer case, so there is a risk of thermal strain accumulating between the heat exchanger that is fixed to the piping.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide a carburizing gas generator configured to absorb expansion of a catalyst section containing a catalyst due to heating, thereby preventing accumulation of metal fatigue and thermal strain in the catalyst section. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following configuration. (1) A carburizing gas generator according to one aspect of the present invention comprises a combustion section including a first gas supply path for supplying a hydrocarbon gas as a raw material, a second gas supply path for supplying a combustion supporting gas, and a combustion chamber for generating combustion gas by incomplete combustion of the hydrocarbon gas and the combustion supporting gas, a dilution section located on the secondary side of the combustion section, and a catalyst section located on the secondary side of the dilution section and equipped with a catalyst, wherein the catalyst section is provided with a catalyst housing tube that houses the catalyst and has an extension section that is extendable and contractible in the direction in which the combustion section and the dilution section are arranged, and wherein the combustion gas that has passed through the dilution section reacts with the heated catalyst in the catalyst section to generate carburizing gas containing carbon monoxide gas and hydrogen gas. (2) In the carburizing gas generator according to (1) of the present invention, it is preferable that a part or all of the catalyst housing pipe is made of at least one of a bellows pipe, a coil pipe, and a curved pipe that is thermally expandable in the longitudinal direction of the catalyst housing pipe.

[0008] (3) A carburizing gas generator according to one aspect of the present invention comprises a combustion section including a first gas supply path for supplying a hydrocarbon gas as a raw material, a second gas supply path for supplying a combustion supporting gas, and a combustion chamber for generating combustion gas by incomplete combustion of the hydrocarbon gas and the combustion supporting gas, a dilution section located on the secondary side of the combustion section, and a catalyst section located on the secondary side of the dilution section and equipped with a catalyst, the catalyst section having a catalyst housing tube in which the catalyst is housed, the dilution section and the combustion section being installed on the primary side of the catalyst housing tube so as to be movable in accordance with thermal expansion or thermal contraction of the catalyst housing tube, and the combustion gas that has passed through the dilution section reacts with the heated catalyst in the catalyst section to generate carburizing gas containing carbon monoxide gas and hydrogen gas.

[0009] (4) In the carburizing gas generator according to (3) of the present invention, it is preferable that flanges are provided at the top and bottom of the catalyst housing pipe, the dilution section and the combustion section are installed on the flange provided at the top, and the dilution section and the combustion section are installed so as to be able to move up and down freely in response to thermal expansion and contraction of the catalyst housing pipe. (5) In the carburizing gas generator according to (4) of the present invention, it is preferable that a lateral displacement prevention guide is provided around the flange portion to restrict the range of lateral displacement of the dilution portion relative to the catalyst portion.

[0010] (6) In the carburizing gas generator according to any one of (1) to (5) of the present invention, it is preferable that the dilution section has a first gas flow path communicating with the combustion chamber, one or more third gas supply paths for supplying a hydrocarbon gas to the first gas flow path, and one or more fourth gas supply paths for supplying an inert gas to the first gas flow path.

[0011] (7) In the carburizing gas generator according to (6) of the present invention, it is preferable that the carburizing gas generator further comprises a reforming section located between the combustion section and the dilution section, the reforming section being located between the combustion chamber and the first gas flow path and including a second gas flow path communicating with the combustion chamber and the first gas flow path, and reforming a portion of the combustion gas into carbon monoxide gas and hydrogen gas. (8) In the carburizing gas generator according to (7) of the present invention, it is preferable that the reforming section includes a dispersion plate for dispersing the flow of the reformed combustion gas. [Effects of the Invention]

[0012] According to the present invention, a catalyst housing tube capable of thermal expansion and contraction in the direction in which the combustion section and dilution section are disposed is provided. Therefore, when combustion gas is supplied to the catalyst section to generate carburizing gas, if the catalyst section expands due to thermal expansion, the catalyst housing tube absorbs this expansion. Furthermore, if the supply of combustion gas is stopped and the catalyst section cools and thermally contracts, the catalyst housing tube absorbs this thermal contraction. This suppresses the load caused by thermal expansion or thermal contraction that is thought to act on the catalyst housing tube and its surrounding areas. Therefore, even if the carburizing gas generator of the present invention is used for a long period of time and thermal expansion and thermal contraction are repeated, the catalyst housing tube and its surrounding areas are less likely to suffer fatigue due to thermal history. Therefore, it is possible to provide a carburizing gas generator that is less susceptible to fatigue damage due to thermal history. [Brief explanation of the drawings]

[0013] [Figure 1] 1A and 1B are diagrams for explaining the configuration of a carburizing gas generator according to a first embodiment of the present invention, in which (A) is a schematic overall view, and (B) is a perspective view showing an example of a bellows tube applied to a catalyst housing tube. [Figure 2] FIG. 2 is a schematic diagram showing the internal structure of a combustion section, a reforming section, and a dilution section of the carburizing gas generator according to the first embodiment. [Figure 3] FIG. 2 is a side view showing a modified example of the bellows tube shown in FIG. [Figure 4] 1A and 1B are diagrams for explaining the configuration of a carburizing gas generator according to a second embodiment of the present invention, in which (A) is a schematic overall view, and (B) is a perspective view showing an example of a coil tube applied to a catalyst housing tube. [Figure 5] FIG. 5 is a side view showing a modified example of the coil tube shown in FIG. [Figure 6] FIG. 10 is an overall schematic view for explaining the configuration of a carburizing gas generator according to a third embodiment of the present invention. [Figure 7] 10 is a schematic side view of a catalyst housing pipe applied to the carburizing gas generator according to the third embodiment. [Figure 8] FIG. 10 is a perspective view of a catalyst housing pipe applied to the carburizing gas generator according to the third embodiment. [Figure 9] FIG. 10 is an overall schematic view for explaining the configuration of a carburizing gas generator according to a fourth embodiment of the present invention. [Figure 10] 10A is a side view showing the configuration of a catalyst section and a lateral displacement prevention guide applied to the carburizing gas generator according to the fourth embodiment, and FIG. 10B is a perspective view showing a modified example of the lateral displacement prevention guide. [Figure 11] FIG. 10 is an explanatory diagram of a simulation result showing the amount of displacement in the X-axis direction acting upon heating in a coil tube applied to the carburizing gas generator of the second embodiment. [Figure 12] FIG. 10 is an explanatory diagram of a simulation result showing the amount of displacement in the Y-axis direction acting upon heating in a coil tube applied to the carburizing gas generator of the second embodiment. [Figure 13]FIG. 10 is an explanatory diagram of a simulation result showing the amount of displacement in the Z-axis direction that occurs when heating in a coil tube applied to the carburizing gas generator of the second embodiment. [Figure 14] FIG. 11 is an explanatory diagram of a simulation result showing the amount of displacement in the X-axis direction acting upon heating in a catalyst housing pipe applied to the carburizing gas generator of the third embodiment. [Figure 15] FIG. 11 is an explanatory diagram of a simulation result showing the amount of displacement in the Y-axis direction acting upon heating in a catalyst housing pipe applied to the carburizing gas generator of the third embodiment. [Figure 16] FIG. 11 is an explanatory diagram of a simulation result showing the amount of displacement in the Z-axis direction acting upon heating in a catalyst housing pipe applied to the carburizing gas generator of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] First Embodiment A carburizing gas generator according to a first embodiment of the present invention will now be described in detail with reference to the drawings, along with a carburizing gas generation method using the same. Note that the drawings used in the following description may show characteristic portions enlarged for the sake of clarity, and the dimensional proportions of the components may not necessarily be the same as those in reality.

[0015] <Carburizing gas generator> First, a carburizing gas generator according to a first embodiment of the present invention will be described. Fig. 1(A) is a schematic diagram showing an example of the configuration of a carburizing gas generator according to the first embodiment. As shown in Fig. 1(A), a carburizing gas generator 10 is generally configured to include, from top to bottom, a combustion section 11, a reforming section 12, a dilution section 13, and a catalyst section 14. Fig. 1(B) shows a bellows pipe 22D that is provided in the catalyst section 14 as described below.

[0016] The combustion section 11 is located vertically above the carburizing gas generator 10. The combustion unit 11 includes a first gas supply path L1 for supplying a hydrocarbon gas as a raw material, a second gas supply path L2 for supplying a combustion-supporting gas, and a combustion chamber 11A for generating combustion gas by incomplete combustion of the hydrocarbon gas and the combustion-supporting gas. The combustion unit 11 has a cylindrical main body 11a having the combustion chamber 11A therein. The upper side of the main body 11a is closed, and the combustion chamber 11A is open downward. Gas supply pipes and on-off valves are connected to flow paths formed on the left and right sides of the main body 11a, respectively, to form the first gas supply path L1 and the second gas supply path L2. The structure of the combustion section 11 is not particularly limited, and a known structure described in a known document (for example, JP 2015-004110 A) can be applied. In this way, in the carburizing gas generator 10, a hydrocarbon gas is supplied from the first gas supply path L1, and a combustion-supporting gas (for example, oxygen gas) is supplied from the second gas supply path L2 into the combustion chamber 11A. In this way, by forming a swirling flow of the hydrocarbon gas and the combustion-supporting gas in the combustion chamber 11A and burning them, a swirling flow flame can be formed in the combustion chamber 11A, and combustion gas can be generated.

[0017] The reforming section 12 is disposed between the combustion section 11 and the dilution section 13 in the carburizing gas generator 10. The reforming section 12 generates the heat required for the dilution section 13 and the reformed gas to be supplied to the dilution section 13. The reformed gas refers to a mixed gas in which part of the combustion gas is reformed into carbon monoxide gas and hydrogen gas. As shown in FIG. 2, the reforming section 12 includes a hollow cylindrical metal tube 15, a refractory material 17 housed inside the metal tube 15 so as to fill it, a gas flow path (second gas flow path) 12A surrounded by the refractory material 17 and positioned in the center of the metal tube 15, and a dispersion plate 16 inside the gas flow path 12A. The gas flow path 12A is located between the combustion chamber 11A and a gas flow path (first gas flow path) 13A in the dilution section 13, which will be described later, and is connected to both the combustion chamber 11A and the gas flow path 13A. Therefore, combustion gas is introduced from the combustion chamber 11A into the gas flow path 12A.

[0018] The interior of the metal tube 15 is filled with a refractory material 17, and the gas flow path 12A is surrounded by the refractory material 17. There are no particular limitations on the refractory material 17 as long as it has excellent heat resistance, and for example, an inorganic material such as ceramic can be used. Furthermore, it is more preferable that the refractory material 17 has a heat-shielding effect and a heat-storing effect. The reforming section 12 has a structure in which refractory material 17 is applied to the inside of the metal tube 15, enhancing heat resistance against combustion gas, and is therefore able to stably retain heat. The temperature inside the reforming section 12 reaches approximately 1500°C. Therefore, the reforming section 12 constituting the carburizing gas generator 10 can stably reform a portion of the combustion gas introduced from the combustion chamber 11A into carbon monoxide gas and hydrogen gas using combustion heat without the need for supplemental heat from the outside.

[0019] The dispersion plate 16 is housed in the gas flow path 12A. Specifically, the dispersion plate 16 is installed in the gas flow path 12A on the secondary side (downstream side) of the gas flow direction, i.e., closer to the dilution section 13. The structure of the dispersion plate 16 is not particularly limited as long as it can disperse (rectify) the flow of the reformed combustion gas, and can be, for example, a structure in which 10 or more pores are arranged in a square array. Furthermore, the material of the dispersion plate 16 is not particularly limited as long as it is a material with excellent heat resistance and fire resistance. The gas flow passage 12A has a small inner diameter at the portion connected to the combustion chamber 11A and an expanded-diameter portion 12a where the inner diameter gradually increases downward above the refractory 17. The gas flow passage 12A has a large-diameter portion 12b with a constant inner diameter at the center of the refractory 17 in the vertical direction. The gas flow passage 12A has a reduced-diameter portion 12c where the inner diameter gradually decreases below the refractory. The gas flow passage 12A is connected to the gas flow passage 13A at the lower end of the reduced-diameter portion 12c. A dispersion plate 16 is installed at the lower end of the large-diameter portion 12b to separate the large-diameter portion 12b from the reduced-diameter portion 12c.

[0020] In the reforming section 12, by providing a dispersion plate 16 in the gas flow path 12A, the heat of the combustion gas supplied to the gas flow path 13A in the dilution section 13 can be uniformly adjusted, and the flow velocity of the combustion gas can be reduced. In this way, by uniformly distributing the heat of the combustion gas supplied to the gas flow path 13A, the catalyst 23 (described below) housed in the catalyst section 14 can be uniformly heated. Furthermore, by reducing the flow velocity of the combustion gas, the time for the combustion gas to pass through the catalyst 23 (described below) can be secured, allowing the combustion gas to come into good contact with the catalyst 23. Therefore, the reaction efficiency between the combustion gas and the catalyst in the catalyst section 14 (described below) can be improved. Furthermore, by reducing the flow velocity of the combustion gas, the residence time of the combustion gas in the reforming section 12 is extended. Therefore, the combustion gas can be stably reformed.

[0021] The dilution section 13 is located on the secondary side (vertically below) of the reforming section 12 in the carburizing gas generator 10. In the dilution section 13, a hydrocarbon gas and an inert gas are supplied to the combustion gas (reformed gas) obtained in the reforming section 12 to dilute the combustion gas. The dilution section 13 has a hollow cylindrical metal pipe 18, a refractory material 20 provided to occupy the interior of the metal pipe 18, and a gas flow path 13A formed to pass vertically through the center side of the refractory material 20. The dilution section 13 is connected to one or more third gas supply paths (hydrocarbon gas supply paths) L3 and one or more fourth gas supply paths (inert gas supply paths) L4. The gas flow path 13A is located on the secondary side of the gas flow path 12A of the reforming section 12, and is connected to the combustion chamber 11A via the gas flow path 12A. Therefore, a reformed gas obtained by reforming a part of the combustion gas in the gas flow path 12A is introduced into the gas flow path 13A. In this example, the metal pipe 18 of the dilution section 13 and the metal pipe 15 of the reforming section 12 have the same outer diameter, so the outer surfaces of the reforming section 12 and the dilution section 13, which are arranged above and below, are continuous and flush with each other.

[0022] A third gas supply path L3 and a fourth gas supply path L4 are independently connected to the gas flow path 13A. The third gas supply path L3 is formed by one or more gas supply pipes around the periphery of the dilution section 13, and is configured to penetrate the refractory material 20 horizontally to reach the gas flow path 13A. The fourth gas supply path L4 is formed by one or more gas supply pipes around the periphery of the dilution section 13, and is configured to penetrate the refractory material 20 horizontally to reach the gas flow path 3A. An on-off valve is incorporated into each of the third gas supply path L3 and the fourth gas supply path L4.

[0023] The third gas supply path L3 supplies a hydrocarbon gas (natural gas) as a diluent gas to the gas flow path 13A. The fourth gas supply path L4 supplies an inert gas (such as nitrogen gas) as a dilution gas to the gas flow path 13A. Although one third gas supply path L3 and one fourth gas supply path L4 are depicted in Figures 1 and 2, a plurality of each of these may be formed around the gas flow path 13A. In the gas flow path 13A, a hydrocarbon gas and an inert gas can be supplied to the combustion gas (reformed gas) supplied from the reforming section 12 to dilute it to an arbitrary composition ratio. Furthermore, by diluting the combustion gas, the combustion gas can be adjusted to an appropriate temperature, thereby suppressing the generation of soot.

[0024] The cross-sectional area of ​​the gas flow passage 13A is smaller than the cross-sectional area of ​​the large diameter section 12b of the reforming section 12. This makes it easier for the hydrocarbon gas and the inert gas to reach the center of the gas flow passage 13A, so that the combustion gas (reformed gas) is mixed uniformly with the hydrocarbon gas and the inert gas. In this embodiment, the fourth gas supply path L4 is disposed on the primary side (upstream side) of the third gas supply path L3 in the gas flow direction of the gas flow path 13A. This configuration allows the hydrocarbon gas to be supplied to the gas flow path 13A upstream of the inert gas, allowing the temperature of the combustion gas to be adjusted by the hydrocarbon gas. Therefore, the carburizing gas generator 10 effectively suppresses soot generation while promoting the decomposition of the hydrocarbon gas into carbon monoxide gas and hydrogen gas using the thermal energy of the combustion gas. Furthermore, the high-temperature water vapor contained in the combustion gas promotes the decomposition of the hydrocarbon gas.

[0025] In this embodiment, the third gas supply path L3 and the fourth gas supply path L4 may be connected to the gas flow path 13A so that they are at the same height in the gas flow direction of the gas flow path 13A. In this case, the vertical height of the dilution section 13 can be shortened, which allows the carburizing gas generator 10 to be made smaller, and this has the advantage of allowing the carburizing furnace 1 to be made smaller. Furthermore, the third gas supply path L3 may be connected to the primary side of the fourth gas supply path L4 in the gas flow direction of the gas flow path 13A. In this configuration, the inert gas can be supplied upstream of the hydrocarbon gas, so the combustion gas can be cooled to an appropriate temperature before the hydrocarbon gas comes into contact with the combustion gas, thereby suppressing the generation of soot.

[0026] In the present embodiment, the third gas supply path L3 and the fourth gas supply path L4 are independently connected to the gas flow path 13A as an example, but the present invention is not limited to this. The third gas supply path L3 and the fourth gas supply path L4 may be connected to the gas flow path 13A after joining on the primary side of the gas flow path 13A, and a mixed gas of a hydrocarbon gas and an inert gas may be supplied to the gas flow path 13A.

[0027] The interior of the metal tube 18 and the periphery of the gas flow path 13A are filled with a refractory material 20. The refractory material 20 is not particularly limited as long as it has excellent heat resistance, and for example, an inorganic material such as ceramic can be used. The refractory material 20 can be the same as the refractory material 17 described above. The dilution section 13 has a structure in which refractory material 20 is installed inside the metal tube 18, enhancing its heat resistance, and therefore can stably retain heat. The temperature of the dilution section 13 must be maintained at a temperature higher than the temperature at which a reaction occurs between the combustion gas and the catalyst in the catalyst section 14. This varies depending on the type of catalyst, but when using a nickel-based catalyst, for example, it is preferable to maintain the temperature of the dilution section 13 at 1050°C or higher.

[0028] The carburizing gas generator 10 of this embodiment has a structure in which the reforming section 12 is disposed on the primary side of the dilution section 13, and since the reforming section 12 can store the heat of combustion in the combustion section 11, it is possible to supplement the heat required in the catalyst section 14 via the dilution section 13. In other words, since the reforming section 12 is in contact with the primary side of the dilution section 13, heat transfers from the reforming section 12 to the dilution section 13. This makes it possible to prevent a drop in the temperature of the catalyst in the catalyst section 14 due to an endothermic reaction of the catalyst.

[0029] In the catalyst section 14, the combustion gas (reformed gas) diluted in the dilution section 13 is brought into contact with a catalyst 23 to generate a carburizing gas with a target gas composition. The catalyst section 14 has a catalyst housing pipe 22, a catalyst 23 housed inside the catalyst housing pipe 22, and an electric heater 24 arranged around the catalyst housing pipe 22. The catalyst housing pipe 22 is made of a heat-resistant alloy, for example, and has a pipe body 22A, with a flange section 22B formed at the upper end of the pipe body 22A and a flange section 22C formed at the lower end of the pipe body 22A. A bellows pipe (expandable section) 22D is integrated with the bottom side of the pipe body 22A. The catalyst housing pipe 22 is made of Inconel 601, for example (linear expansion coefficient: 13.75×10 -6 It is made of heat-resistant alloys with a low coefficient of linear expansion, such as SUS304.

[0030] The pipe main body 22A has the same inner diameter except for the bellows pipe 22D. The bellows pipe 22D is made of a bellows pipe and is configured to be slightly expandable and contractible in the length direction of the pipe main body 22A (vertical direction: length direction of the catalyst housing pipe 22). The upper end of the pipe body 22A is a straight pipe-shaped connecting portion 22E, which is integrated with the center of the flange portion 22B, and the upper open end of the connecting portion 22E is open at the center of the flange portion 22B. The lower end of the pipe body 22A is a straight pipe-shaped connecting portion 22F, which is integrated with the center of the flange portion 22C, and the lower open end of the connecting portion 22F is open at the center of the flange portion 22C. The catalyst 23 is accommodated in the connecting portion 22E on the upper end side of the pipe body 22A.

[0031] The catalyst 23 is not particularly limited as long as it can convert the combustion gas into a carburizing gas consisting of carbon monoxide gas, hydrogen gas, and an inert gas. Examples of such catalysts include nickel-based catalysts. The catalyst 23 may be contained throughout the entire interior of the tube body 22A, or may be contained only in a portion of the tube body 22A. That is, there may be space within the tube body 22A that is not filled with the catalyst 23. The catalyst 23 may be a particle aggregate, a porous body, or a solid body with numerous ventilation holes, and is preferably structured to allow the combustion gas (reformed gas), hydrocarbon gas, and inert gas supplied to the catalyst section 14 to easily pass through.

[0032] The pipe body 22A is connected to the furnace body 2 by placing a flange portion 22C on the lower end side thereof on the upper surface of the furnace body 2 described later. In addition, the lower end opening of the pipe body 22A is opened in the center of the flange portion 22C, so that the internal flow path of the pipe body 22A is connected to the supply port 2a of the furnace body 2 described later. The dilution section 13 is installed on the flange section 22B on the upper end side of the pipe body 22A, and the lower end of the gas flow path 13A of the dilution section 13 is connected to the upper end opening of the pipe body 22A. This structure makes it possible to supply combustion gas (reformed gas), hydrocarbon gas, and inert gas from the gas flow path 13A to the catalyst section 14. A cylindrically disposed electric heater 24 is provided around the pipe body 22A between the flange portions 22B and 22C. The electric heater 24 is connected to a power supply source (not shown) and generates heat when energized as needed, thereby heating the pipe body 22A and its internal flow path to the required temperature.

[0033] <Carburizing gas generation method> Next, the carburizing gas generating method according to this embodiment will be described with reference to the drawings. In the carburizing gas generating method, carburizing gas is generated using the carburizing gas generating apparatus 10 described above.

[0034] 1 and 2, in the carburizing gas generation method, first, a hydrocarbon gas is supplied from a first gas supply path L1 and a combustion-supporting gas (e.g., oxygen gas) is supplied from a second gas supply path L2 to burners (not shown) in the combustion section 11, and the hydrocarbon gas and the combustion-supporting gas are combusted in the combustion chamber 11A while forming a swirling flow, thereby generating combustion gas in the combustion chamber 11A. Then, electricity is applied to the electric heater 24 to generate heat, and the catalyst 23 in the catalyst section 14 is heated to an appropriate temperature.

[0035] When generating combustion gas in the combustion section 11, the oxygen ratio of the hydrocarbon gas to the combustion-supporting gas is preferably 1:0.5 to 0.8. Furthermore, from the viewpoint of obtaining combustion heat, the oxygen ratio is more preferably 1:0.60 to 0.80. In the combustion section 11, by setting the oxygen ratio to 0.5 or more, it is possible to suppress the generation of soot. Furthermore, by setting the oxygen ratio to 0.8 or less, it is possible to suppress the generation of carbon dioxide and water that react with carbon monoxide gas. This allows carbon monoxide gas to be generated efficiently in the combustion section 11. The oxygen ratio is the amount of combustion-supporting gas defined below. "Oxygen ratio" = "Amount of combustion supporting gas supplied to the burner" ÷ "Amount of combustion supporting gas required for complete combustion of hydrocarbon gas"

[0036] Next, the generated combustion gas is supplied from the combustion chamber 11A to the gas flow path 12A of the reforming section 12, where the heat of the combustion gas is used to reform a portion of the combustion gas into carbon monoxide gas and hydrogen gas. In the reforming section 12, unburned hydrocarbon gases in the combustion gas can be decomposed into carbon monoxide and hydrogen, so that carburizing gas can be generated efficiently. Next, the combustion gas after being partially reformed into carbon monoxide gas and hydrogen gas is supplied from the gas flow path 12A to the gas flow path 13A of the dilution section 13, and a hydrocarbon gas and an inert gas are supplied to the combustion gas to obtain a diluted gas.

[0037] Here, when supplying the hydrocarbon gas and the inert gas to the combustion gas in the gas flow path 13A, they can be supplied separately using the independent third gas supply path L3 and fourth gas supply path L4, respectively. This makes it possible to prevent the thermal energy of the combustion gas from being absorbed by the inert gas. Therefore, decomposition of the hydrocarbon gas by the thermal energy of the combustion gas is promoted, and carbon monoxide gas and hydrogen gas can be efficiently generated.

[0038] Next, in the catalyst section 14, the dilution gas is reacted with the heated catalyst to generate a carburizing gas containing carbon monoxide gas, hydrogen gas, and an inert gas. According to this embodiment, the combustion gas is diluted with a hydrocarbon gas and an inert gas before reacting with the catalyst, so the dilution conditions can be adjusted, thereby generating a carburizing gas with a desired gas composition.

[0039] <Carburizing furnace> Next, the configuration of a carburizing furnace equipped with the carburizing gas generator of this embodiment will be described. Figure 1 is a schematic diagram showing an example of the configuration of a carburizing furnace equipped with the carburizing gas generator 10 of this embodiment. As shown in FIG. 1, the carburizing furnace 1 is generally configured to include a furnace body 2 having a heating chamber 2A therein, and a carburizing gas generator 10 for generating carburizing gas. The carburizing furnace 1 carburizes the workpiece S accommodated in the heating chamber 2A using a carburizing gas consisting of carbon monoxide gas, hydrogen gas, and an inert gas. (furnace body) The furnace body 2 is a furnace body having at least a heating chamber 2A capable of accommodating a workpiece S to be carburized. The furnace body 2 is also provided with a supply port 2a for introducing carburizing gas into the heating chamber 2A, and an exhaust port 2b for discharging atmospheric gas from the heating chamber 2A.

[0040] Supply port 2a is located on the upper surface of heating chamber 2A, which allows carburizing gas generated by carburizing gas generator 10 of this embodiment, which is disposed above furnace body 2 as described below, to be introduced directly into heating chamber 2A from above. The exhaust port 2b is located at the bottom of the side surface of the heating chamber 2A. The exhaust port 2b allows the atmospheric gas inside the heating chamber 2A to be discharged to the outside after the carburizing treatment has been carried out. The structure of the furnace body 2 is not particularly limited, and a known structure described in a known document (for example, JP 2015-004110 A) can be applied.

[0041] (Carburizing furnace) 2, a carburizing furnace 1 equipped with a carburizing gas generator 10 of this embodiment is connected to the furnace body 2 so that the carburizing gas generator 10 is located above the furnace body 2. That is, as shown in FIGS. 1 and 2, the gas flow path 13A of the catalyst section 14 is connected to the heating chamber 2A via the supply port 2a and the catalyst section 14, and the carburizing gas discharged from the catalyst section 14 is introduced directly into the heating chamber 2A without being heated in any intermediate flow path. In the carburizing furnace 1, the amount of carburizing gas generated by the carburizing gas generator 10 of this embodiment (i.e., the amount of carburizing gas supplied to the heating chamber 2A of the furnace body 2) is set to 2 to 30 m with respect to the volume of the heating chamber 2A. 3 / h is preferable. This eliminates the need to generate excess carburizing gas in the carburizing gas generator 10, making it possible to reduce the size of the carburizing gas generator 10 and, in turn, the size of the carburizing furnace 1.

[0042] Furthermore, in the carburizing furnace 1, the temperature of the carburizing gas generated in the carburizing gas generator 10 (i.e., the temperature of the carburizing gas introduced into the heating chamber 2A of the furnace body 2) may be 700 to 1000°C, preferably 800 to 950°C, and more preferably 870 to 930°C. This eliminates the need to further heat the carburizing gas generated in the carburizing gas generator 10 before supplying it to the heating chamber 2A, eliminating the need for an additional heating mechanism. This allows for the carburizing gas generator 10 to be made more compact, and ultimately the carburizing furnace 1 to be made more compact, resulting in excellent thermal efficiency. The carburizing furnace 1 may also be provided with a heat supply mechanism that uses the exhaust heat discharged from the furnace body 2 as a heat source for the carburizing gas generator 10 of this embodiment.

[0043] The furnace body 2 needs to be supplied with carburizing gas in the above-mentioned temperature range, and the reforming gas needs to be heated to a temperature at which the catalyst reacts sufficiently in the catalyst section 14. For this reason, the electric heater 24 provided in the carburizing gas generator 10 is energized to generate heat as needed, thereby heating the tube body 22A to the required temperature. This heating causes thermal expansion of the pipe body 22A equipped with the bellows tube 22D, but the bellows tube 22D is expandable to some extent in the longitudinal direction (vertical direction), and the elongation of the pipe body 22A caused by thermal expansion is absorbed by the bellows tube 22D. This eliminates or reduces the risk of strain accumulating in the pipe body 22A, flange portions 22B and 22C, and their surrounding areas. Furthermore, when the generation of carburizing gas is stopped and heating by electric heater 24 is stopped, the temperature of catalyst portion 14 drops, but at this stage catalyst portion 14 undergoes thermal contraction. The thermal contraction of catalyst portion 14 is absorbed by bellows tube 22D. This eliminates or reduces the risk of strain accumulation due to thermal contraction. In other words, strain due to thermal expansion or contraction of catalyst portion 14 is absorbed by the expansion and contraction of tube main body 22A, which is equipped with thermally expandable bellows tube 22D.

[0044] Therefore, even if the carburizing gas generator 10 is operated repeatedly, there is little risk of fatigue accumulation in the catalyst section 14, which includes the pipe main body 22A and its surroundings and the flange sections 22B, 22C and their surroundings, and problems such as fatigue failure will not occur. For example, if the length of the pipe body 22A is about 500 mm and the pipe body 22A is made of Inconel 601, the pipe body 22A will expand by about 7 mm when heated to about 1000°C. The bellows pipe 22D absorbs this expansion by expanding and contracting, thereby preventing fatigue failure of the carburizing gas generator 10. Since the bellows tube 22D is provided for the purpose of absorbing the thermal expansion and contraction described above, the entire tube body 22A may be made of a bellows tube, or only a part of the tube body 22A may be made of a bellows tube.

[0045] <Modification of the first embodiment> FIG. 3 is a side view showing a modified example of a catalyst housing pipe that can be applied to the carburizing gas generator 10 of the first embodiment. The catalyst housing pipe 26 in this example has a bellows pipe (expandable portion) 27A on the bottom side of a straight pipe body 27, a flange portion 28 at the upper end (one end) of the pipe body 27, and a flange portion 29 at the lower end (other end) of the pipe body 27. In this example, the catalyst housing pipe 26 achieves its purpose by having the thermally expandable bellows pipe 27A absorb the thermal expansion and contraction of the pipe body 27 that occurs when the catalyst is heated or when it is cooled after heating.

[0046] Second Embodiment A carburizing gas generator according to a second embodiment of the present invention will now be described. Fig. 4(A) is a schematic diagram showing an example of the configuration of a carburizing gas generator according to a second embodiment. As shown in Fig. 4(A), a carburizing gas generator 30 according to the second embodiment is generally configured to include, from top to bottom, a combustion section 11, a reforming section 12, a dilution section 13, and a catalyst section 31. Fig. 4(B) shows a catalyst housing pipe 32 that is provided in the catalyst section 31 as described below. In the carburizing gas generator 30 of the second embodiment, the combustion section 11, reforming section 12, and dilution section 13 are configured similarly to those of the first embodiment, and therefore a description of the similar configurations will be omitted.

[0047] The second embodiment differs from the first embodiment in the configuration of the catalyst section 31. The catalyst section 31 has a catalyst housing pipe 32, a catalyst (not shown) housed inside the catalyst housing pipe 32, and an electric heater 24 arranged around the catalyst housing pipe 32. Catalyst housing pipe 32 is made of a heat-resistant alloy and has a coil-shaped pipe main body (expandable portion) 32A, with flange portion 32B formed at the upper end of pipe main body 32A and flange portion 32C formed at the lower end of pipe main body 32A. Coil pipe 32D is incorporated into the portion extending from the top to the bottom of pipe main body 32A. The upper end of coil pipe 32D is integrated with the center of flange portion 32B via connecting pipe 32E, which is also made of a pipe, and the lower end of coil pipe 32D is integrated with the center of flange portion 32C via connecting pipe 32F. The coil tube 32D is arranged so that its central winding axis coincides with the central axis of the catalyst section 31. That is, in the carburizing gas generator 30, the central winding axis of the coil tube 32D coincides with the vertical direction. The catalyst housing pipe 32 is made of, for example, Inconel 601 (linear expansion coefficient: 13.75×10 -6 It is made of heat-resistant alloys with a low coefficient of linear expansion, such as SUS304.

[0048] The upper end of coil tube 32D incorporated into tube main body 32A is unwound in a coil near flange portion 32B to form connecting tube 32E. Connecting tube 32E is integrated into the center of flange portion 32B, and the upper open end of connecting tube 32E opens at the center of flange portion 32B. The lower end of coil tube 32D is unwound in a coil near flange portion 32C to form connecting tube 32F. Connecting tube 32F is integrated into the center of flange portion 32C, and the lower open end of connecting tube 32F opens at the center of flange portion 32C. The cylindrical electric heater 24 provided around the pipe main body 32A between the flange portion 32B and the flange portion 32C is the same as the electric heater 24 in the first embodiment.

[0049] In the second embodiment, the gas flow path 13A of the dilution section 13 is connected to a connecting pipe 32E at the upper end of the pipe body 32A through an opening at the center of the upper surface of the flange portion 32B. A connecting pipe 32F at the lower end of the pipe body 32A is connected to the supply port 2a of the furnace body 2 through an opening at the center of the lower surface of the flange portion 32C.

[0050] In the second embodiment, a mixed gas of combustion gas (reformed gas), hydrocarbon gas, and inert gas is introduced into the pipe body 32A through the gas flow path 13A of the dilution section 13. Carburizing gas can be generated by bringing this mixed gas into contact with a catalyst (not shown) housed in the pipe body 32A, and the carburizing gas can be introduced into the heating chamber 2A of the furnace body 2 through the supply port 2a.

[0051] Electricity is applied to the electric heater 24 provided in the carburizing gas generator 30 to generate heat as needed, heating the pipe main body 32A and the catalyst therein to the required temperature. This heating causes the pipe main body 32A, which includes the coil pipe 32D, to stretch, but because the coil pipe 32D is capable of expanding and contracting to some extent in the vertical direction, the stretching of the pipe main body 32A caused by heating is absorbed by the coil pipe 32D. Here, the vertical direction can be said to be the length direction of the catalyst housing pipe 32. This eliminates or reduces the risk of thermal strain accumulating in the pipe main body 32A, flanges 32B and 32C, and their surrounding areas. Therefore, even if the carburizing gas generator 30 is repeatedly operated and heated, fatigue accumulation can be prevented in the catalyst section 31, which includes the pipe main body 32A and its surroundings and the flanges 32B and 32C and their surroundings. As a result, problems such as fatigue failure do not occur in the carburizing gas generator 30. Since the coil tube 32D is provided for the purpose of absorbing the aforementioned elongation, the entire tube body 32A may be made of a coil tube, or only a part of the tube body 32A may be made of a coil tube.

[0052] <Modification of the second embodiment> FIG. 5 shows a modified example of a catalyst housing pipe that can be applied to the carburizing gas generator 30 of the second embodiment. A catalyst housing pipe 32' in this example has a pipe main body 32A, and similarly to the second embodiment, has a coil pipe 32D, a connecting pipe 32E at its upper end, and a connecting pipe 32F at its lower end.

[0053] <Third embodiment> A carburizing gas generator according to a third embodiment of the present invention will be described. 6 to 8 are schematic diagrams showing an example of the configuration of a carburizing gas generator according to the third embodiment. As shown in Fig. 6, a carburizing gas generator 40 of the third embodiment is generally configured to include, from top to bottom, a combustion section 11, a reforming section 12, a dilution section 13, and a catalyst section 41. Figs. 7 and 8 show a catalyst housing pipe 42 that is provided in the catalyst section 41 as described below. In the carburizing gas generator 40 of the third embodiment, the configurations of the combustion section 11, reforming section 12, and dilution section 13 are the same as those of the first embodiment, and therefore a description of the same configurations will be omitted.

[0054] The third embodiment differs from the first embodiment in the configuration of the catalyst section 41. The catalyst section 41 has a catalyst housing pipe 42, a catalyst (not shown) housed inside the catalyst housing pipe 42, and an electric heater 24 arranged around the catalyst housing pipe 42. The catalyst housing pipe 42 is made of a heat-resistant alloy and has a curved pipe (expandable portion) 42A, with a flange portion 42B formed at the upper end of the curved pipe 42A and a flange portion 42C formed at the lower end of the curved pipe 42A. The curved pipe 42A has multiple (three in the examples of Figures 7 and 8) straight pipe sections 42a extending in the longitudinal direction (vertical direction) of the catalyst section 41 and elbow pipe sections 42b connecting the upper ends or lower ends of these straight pipe sections 42a. The catalyst housing tube 42 is made of, for example, Inconel 601 (linear expansion coefficient: 13.75×10 -6 It is made of heat-resistant alloys with a low coefficient of linear expansion, such as SUS304.

[0055] The upper end of the bending pipe 42A is connected to a straight connecting pipe 42E near the flange portion 42B. The connecting pipe 42E is integrated into the center of the flange portion 42B, and the open end on the upper end side of the connecting pipe 42E opens at the center position of the flange portion 42B. The lower end of the bending pipe 42A is connected to a straight connecting pipe 42F near the flange portion 42C. The connecting pipe 42F is integrated into the center of the flange portion 42C, and the open end on the lower end side of the connecting pipe 42F opens at the center position of the flange portion 42C. The cylindrical electric heater 24 provided around the bending pipe 42A between the flange portion 42B and the flange portion 42C is the same as the electric heater 24 in the first embodiment.

[0056] In the third embodiment, the gas flow path 13A of the dilution section 13 is connected to a connecting pipe 42E at the upper end of the curved pipe 42A through an opening at the center of the upper surface of the flange portion 42B. A connecting pipe 42F at the lower end of the curved pipe 42A is connected to the supply port 2a of the furnace body 2 through an opening at the center of the lower surface of the flange portion 42C.

[0057] In the third embodiment, a mixed gas of combustion gas (reformed gas), hydrocarbon gas, and inert gas is introduced into the curved pipe 42A through the gas flow path 13A of the dilution section 13. The mixed gas is brought into contact with a catalyst (not shown) in the curved pipe 42A to generate carburizing gas, which can be introduced into the heating chamber 2A of the furnace body 2 through the supply port 2a.

[0058] Electricity is applied to the electric heater 24 provided in the carburizing gas generator 40 to generate heat as needed, heating the curved pipe 42A to the required temperature. This heating causes the catalyst housing pipe 42 to elongate in the vertical direction or other directions, but as the straight pipe section 42a and the elbow pipe section 42b elongate individually, the curved pipe 42A as a whole deforms to absorb the vertical elongation. In this case, the direction of elongation or deformation of the curved pipe 42A, inside the electric heater 24, is either along the central axis of the straight pipe section 42a, or a direction perpendicular to the central axis of the straight pipe section 42a, or a direction intersecting the central axis. That is, since the direction in which the combustion section 11 and the dilution section 13 are arranged is the vertical direction, the direction in which the curved pipe 42A extends or deforms is the vertical direction in which they are arranged, or another direction intersecting the vertical direction. The curved pipe 42A can be deformed in the vertical direction or other directions. This eliminates or reduces the risk of strain accumulating in the curved pipe 42A, the flanges 42B and 42C, and their surrounding areas. Therefore, even if the carburizing gas generator 40 is repeatedly operated and heated, there is little risk of metal fatigue occurring in the catalyst part 41, which includes the curved pipe 42A and its surrounding area and the flanges 42B and 42C and their surrounding areas, and there is no risk of problems such as fatigue fracture occurring.

[0059] <Fourth embodiment> A carburizing gas generator according to a fourth embodiment of the present invention will be described. 9 and 10(A) are schematic diagrams showing an example of the configuration of a carburizing gas generator according to the fourth embodiment. As shown in Fig. 9, a carburizing gas generator 50 according to the fourth embodiment is roughly configured to include, from top to bottom, a combustion section 11, a reforming section 12, a dilution section 13, and a catalyst section 51. In the carburizing gas generator 50 of the fourth embodiment, the configurations of the combustion section 11, reforming section 12, and dilution section 13 are the same as those of the first embodiment, and therefore a description of the same configurations will be omitted.

[0060] The fourth embodiment differs from the first embodiment in the configuration of the catalyst section 51. The catalyst section 51 has a catalyst housing pipe 52, a catalyst (not shown) housed inside the catalyst housing pipe 52, and an electric heater 24 arranged around the catalyst housing pipe 52. The catalyst housing pipe 52 is made of a heat-resistant alloy and has a straight pipe body 52A, with a flange portion 52B formed at the upper end of the pipe body 52A and a flange portion 52C formed at the lower end of the pipe body 52A. The catalyst housing pipe 52 is made of, for example, Inconel 601 (linear expansion coefficient: 13.75×10 -6 It is made of heat-resistant alloys with a low coefficient of linear expansion, such as SUS304.

[0061] The upper end of the pipe body 52A is integrated with the center of the flange portion 52B, and the open end on the upper end side of the pipe body 52A is open at the center position of the flange portion 52B. The lower end of the pipe body 52A is integrated with the center of the flange portion 52C, and the open end on the lower end side of the pipe body 52A is open at the center position of the flange portion 52C. The cylindrical electric heater 24, which is provided around the pipe body 52A between the upper flange 52B and the lower flange 52C, is the same as the electric heater 24 in the first embodiment. The cylindrical electric heater 24 is placed on a disk-shaped insulating board 55, which is installed on the flange 52C. A ring-shaped pedestal 56 is placed below the lower flange 52C, and this pedestal 56 is installed on the top of the furnace body 2.

[0062] The dilution section 13 is placed loosely on the flange portion 52B at the upper end of the catalyst housing pipe 52. That is, the dilution section 13, the reforming section 12, and the combustion section 11 are placed in that order on the flange portion 52B. In this example, a bottom flange 13B is formed at the bottom of the dilution section 13, and the bottom flange 13B is placed on the flange portion 52B via a packing material such as a spiral packing. The flange portion 52B is also installed so as to overlap the upper surface of a ring-shaped flange plate 57, and the bottom flange 13B of the dilution section 13 is placed on top of this via a spiral packing. These are integrated with bolts (not shown) that connect the flange plate 57 and the bottom flange 13B. A shallow recess is formed on the upper surface of the flange plate 57, and the flange portion 52B and the spiral packing are stacked in this recess, with the dilution section 13 placed on top of them.

[0063] Plate- or rod-shaped lateral displacement prevention guides 58 are attached to the outer periphery of the flange disk 57 at four locations around the circumference so as to protrude radially outward from the flange disk 57. A through hole 58a is formed in the center of the tip end of the lateral displacement prevention guide 58. A support frame (not shown) is provided around the flange plate 57, and a guide piece 59 is fixed to this support frame. A bolt-type support bracket 60 is provided so as to pass vertically through this guide piece 59. This support bracket 60 is attached to the guide piece 59 so that the shaft portion 61 of the shaft passes through the through hole 58a of the lateral displacement prevention guide 58. The shaft portion 61 of the support bracket 60 is provided so as to protrude a predetermined length above the lateral displacement prevention guide 58.

[0064] The upper flange portion 52B of the catalyst housing pipe 52 is placed on the upper surface of the flange plate 57, and the dilution section 13 is placed on top of that via a spiral packing. When the electric heater 24 is energized to heat the catalyst housing pipe 52 and the catalyst housing pipe 52 expands due to heat, the upper flange portion 52B moves slightly upward. In response to the upward movement of the upper flange portion 52B, the combustion section 11, the reforming section 12, and the dilution section 13 can also move slightly upward. As the flange portion 52B and the flange plate 57 rise, the lateral displacement prevention guide 58 also rises along the shaft portion 61. Because the shaft portion 61 of the support bracket 60 is inserted into the through hole 58a, the lateral displacement prevention guide 58 can rise along the shaft portion 61 while preventing the dilution section 13 from shifting laterally.

[0065] In the fifth embodiment, a mixed gas of a combustion gas (reformed gas), a hydrocarbon gas, and an inert gas is introduced into the pipe body 52A of the catalyst housing pipe 52 through the gas flow path 13A of the dilution section 13. By bringing this mixed gas into contact with the catalyst inside the pipe body 52A, a carburizing gas can be generated, and the carburizing gas can be introduced into the heating chamber 2A of the furnace body 2 from the supply port 2a.

[0066] The electric heater 24 provided in the carburizing gas generator 50 is energized to generate heat as needed, heating the pipe body 52A to the required temperature. This heating causes the pipe body 52A to expand vertically, but the dilution section 13 is simply placed on the flange section 53B. Therefore, the movable flange section 52B, dilution section 13, reforming section 12, and combustion section 11 rise as the pipe body 52A expands. Furthermore, when heating by the electric heater 24 is stopped and the temperature of the catalyst housing pipe 52 drops, the catalyst housing pipe 52 contracts in the vertical direction, but the dilution section 13 is simply placed on the flange section 52B. Therefore, the flange section 52B, dilution section 13, reforming section 12, and combustion section 11, which are movable up and down, move down as the catalyst housing pipe 52 contracts. As explained above, the dilution section 13, reforming section 12, and combustion section 11 move up and down in accordance with the up and down movement of the flange section 52B.

[0067] Therefore, even if catalyst housing pipe 52 thermally expands or contracts, there is no risk of load acting on pipe main body 52A, flange portions 52B and 52C, and their surrounding areas. Therefore, even if carburizing gas generator 50 is repeatedly operated and pipe main body 52A expands due to thermal expansion or thermally contracts due to cooling, there is no risk of metal fatigue acting on catalyst portion 51, which includes pipe main body 52A and its surrounding area and flange portions 52B and 52C and their surrounding areas. Therefore, even in the structure of the fifth embodiment, problems such as fatigue failure due to metal fatigue do not occur in catalyst housing pipe 52 and its surrounding areas.

[0068] When the dilution section 13, reforming section 12, and combustion section 11 repeatedly move up and down as the catalyst housing pipe 52 is heated and cooled, there is a risk that the position of the central axis of the pipe main body 52A and the position of the central axis of the dilution section 13 may become misaligned with each other in the horizontal direction (toward the surface of the flange section 52B on the upper end side). However, the lateral displacement prevention guide 58 restricts the lateral displacement of the dilution section 13, so the dilution section 13 does not shift sideways.

[0069] FIG. 10(B) shows a modified example of the lateral deviation prevention guide. In this modified example, a rectangular adjustment plate 66 is suspended along a part of a base frame 65 that is installed around the flange plate 57. A screw shaft 67 is provided so as to penetrate both ends of the adjustment plate 66 and the base frame 65 above it, and a plurality of adjustment nuts 68 (two in the illustrated example) are screwed onto the upper side of the screw shaft 67 that protrudes above the base frame 65. A head (not shown) formed on the lower end side of the screw shaft portion 67 is set on the underside of the adjustment plate 66. The screw shaft portion 67 is formed to have a length that protrudes downward from the pedestal frame 65 by a predetermined length, so that the adjustment plate 66 is suspended below the pedestal frame 65 at a position slightly spaced apart from the pedestal frame 65, almost horizontally.

[0070] A support pin 69 protrudes from the upper surface of the center of the adjustment plate 66, and this support pin 69 passes through a through hole 65a formed in the pedestal frame 65 above it, protruding a predetermined length above the pedestal frame 65. According to the above structure, the vertical position of the adjustment plate 66 can be adjusted by adjusting the screw engagement position of the adjustment nut 68 with respect to the screw shaft portion 67. This makes it possible to adjust the protruding length of the support pin 69 protruding from the top surface of the pedestal frame 65.

[0071] In this modification, the support pin 69 is inserted into the through hole 58a of the lateral displacement prevention guide 58 in the same manner as the shaft portion 61 shown in Figure 10(a), allowing the flange disk 57 to move up and down. As the flange disk 57 moves up and down, the dilution section 13, reforming section 12, and combustion section 11 also move up and down. In addition, the support pin 69 prevents the flange disk 57 from moving in the horizontal direction, preventing the dilution section 13 from moving sideways. In this modification, the vertical height of the support pin 69 can be adjusted by adjusting the position at which the adjusting nut 68 is screwed onto the threaded shaft portion 67. This allows the vertical position of the support pin 69 to be adjusted to match the height of the lateral displacement prevention guide 58, making it easy to align it with the flange disk 57 when assembling the carburizing gas generator 50.

[0072] "Simulation test of thermal displacement" 11 to 13 show the results of a simulation using a static structural analysis method for the amount of thermal displacement when the catalyst housing pipe 32 according to the second embodiment shown in FIG. 4 is used. In this simulation, the linear expansion coefficient is 13.75×10 -6 On the premise that the catalyst housing tube is made of Inconel 601, the outer diameter of the upper flange is 289 mm, the thickness is 5 mm, the outer diameter of the lower flange is 200 mm, the thickness is 16 mm, the coil radius of the coil tube is 50 mm, the wall thickness of the coil tube is 2.8 mm, the length of the coil tube is approximately 2000 mm, and the flange spacing is 521 mm, and a simulation was carried out in which the tube was heated from room temperature to 1000°C. The software used for the analysis was "Ansys Workbench Mechanical 2023R1." In this simulation test, a thermal structural analysis was carried out on the catalyst tube for a converter furnace for both water pipe and coil pipe shapes, with the aim of confirming the thermal displacement distribution and equivalent stress distribution.

[0073] FIG. 11 shows the results of a simulation of the amount of displacement in the X-axis direction (radial direction of the coil tube), FIG. 12 shows the results of a simulation of the amount of displacement in the Y-axis direction (direction perpendicular to the X-axis), and FIG. 13 shows the results of a simulation of the amount of displacement in the Z-axis direction (direction of the central axis of the coil tube). From the results shown in Figures 11, 12 and 13, it was found that when a catalyst housing tube with a coiled tube is used, no large displacement occurs in any of the X-axis, Y-axis and Z-axis directions. This shows that when the catalyst housing tube with the above-mentioned coiled tube is used, the carburizing gas generator is not affected by thermal strain.

[0074] 14 to 16 show the results of a simulation using a static structural analysis method for the amount of thermal displacement when a catalyst housing pipe 42 equipped with a curved pipe 42A according to the third embodiment shown in FIGS. 6 to 8 is used. In this simulation, the linear expansion coefficient is 13.75×10 -6 On the premise that the catalyst housing pipe is made of Inconel 601, the outer diameter of the upper flange is 289 mm, the thickness is 5 mm, the outer diameter of the lower flange is 200 mm, the thickness is 16 mm, the length of the straight pipe part of the curved pipe is approximately 280 mm, the radius of curvature of the elbow pipe part is approximately 30 mm, the thickness of the straight pipe part and elbow pipe part is 2.8 mm, and the flange part spacing is 521 mm, and a simulation was carried out in which the catalyst housing pipe is heated from room temperature to 1000°C.

[0075] Figure 14 shows the results of the displacement simulation in the X-axis direction (the direction perpendicular to the length of the straight pipe section), Figure 15 shows the results of the displacement simulation in the Y-axis direction (the direction perpendicular to the X-axis), and Figure 16 shows the results of the displacement simulation in the Z-axis direction (the length of the straight pipe section). From the results shown in Figs. 14, 15 and 16, it was found that when a catalyst housing pipe with a curved pipe is used, a certain degree of displacement occurs in the elbow pipe and its vicinity. However, it is believed that the amount of displacement shown in FIGS. 14 to 16 can be sufficiently absorbed by ensuring a distance of about 10 mm or more between the electric heater provided on the outer periphery of the bending tube and the bending tube. [Example]

[0076] A prototype catalyst housing tube was fabricated in the shape shown in Figure 3, in which a bellows tube with a length of about 1 / 10 of the tube body was welded to a straight tube body with a length of 520 mm made of Inconel 601. This catalyst housing tube was incorporated into the catalyst section of a carburizing gas generator with the configuration shown in Figures 1 and 2, and an operation test was carried out in which the catalyst housing tube was heated to 1000°C with an electric heater. As a result, even when the catalyst was heated to 1000°C during operation, no problems such as damage to the catalyst occurred.

[0077] A prototype catalyst housing tube was manufactured, having the shape shown in Figure 5, and a coiled tube made of Inconel 601 with an outer diameter 1 / 5 the length of the catalyst section. This catalyst housing tube was incorporated into the catalyst section of a carburizing gas generator configured as shown in Figure 4, and an operation test was carried out in which the catalyst housing tube was heated to 1000°C by an electric heater. As a result, even when the catalyst was heated to 1000°C during operation, no problems such as damage to the catalyst occurred.

[0078] Using a catalyst housing pipe 52 made of Inconel 601 and configured as shown in Figure 10, a carburizing gas generator was assembled in which a dilution section, a reforming section, and a combustion section were placed on the flange of the catalyst housing pipe 52. An operation test was carried out by energizing an electric heater and heating to 1000°C. As a result, when the catalyst was operated while heated to 1000°C, no problems such as damage to the catalyst occurred even though the catalyst housing tube expanded due to thermal expansion. From the above test results, it was found that the carburizing gas generators corresponding to the above-mentioned embodiments are devices that do not cause problems such as damage to the catalyst part when operated with the catalyst heated to a high temperature of about 1000°C. [Explanation of symbols]

[0079] 1...Carburizing furnace, 2...furnace body, 2A...heating chamber, S...workpiece, 10...Carburizing gas generator, 11...Combustion section, 11A...Combustion chamber, 12... reforming section, 12A... gas flow path (second gas flow path), 13...dilution section, 13A...gas flow path (first gas flow path), L1: First gas supply path L2: second gas supply path, L3: Third gas supply path (hydrocarbon gas supply path), L4: Fourth gas supply path (inert gas supply path), 14...catalyst section, 22... catalyst housing pipe, 22D... bellows pipe (expandable part), 23... catalyst, 24... electric heater, 26... catalyst housing pipe, 27... pipe body, 27A... bellows pipe (expandable portion), 30...Carburizing gas generator, 31...Catalyst unit, 32... catalyst housing pipe, 32A... pipe main body (expandable portion), 40...Carburizing gas generator, 41...Catalyst unit, 42... catalyst housing pipe, 42A... curved pipe (expandable portion), 50...Carburizing gas generator, 52...Catalyst housing pipe, 52A...Pipe body, 52B...Flange portion, 52C... flange portion, 57... flange plate, 58... lateral displacement prevention guide, 59... guide piece, 61...Shaft.

Claims

1. a combustion unit including a first gas supply path for supplying a hydrocarbon gas as a raw material, a second gas supply path for supplying a combustion-supporting gas, and a combustion chamber for generating a combustion gas by incomplete combustion of the hydrocarbon gas and the combustion-supporting gas; a dilution section located on the secondary side of the combustion section; a catalyst section located on the secondary side of the dilution section and including a catalyst; the catalyst section includes a catalyst housing pipe that houses the catalyst and has an expandable section that is expandable in a direction in which the combustion section and the dilution section are arranged, a carburizing gas generator that generates a carburizing gas containing carbon monoxide gas and hydrogen gas by reacting the combustion gas that has passed through the dilution section with the heated catalyst in the catalyst section.

2. 2. The carburizing gas generator according to claim 1, wherein a part or all of the catalyst housing pipe is made of at least one of a bellows pipe, a coil pipe, and a curved pipe that is thermally expandable in the length direction of the catalyst housing pipe.

3. a combustion unit including a first gas supply path for supplying a hydrocarbon gas as a raw material, a second gas supply path for supplying a combustion-supporting gas, and a combustion chamber for generating a combustion gas by incomplete combustion of the hydrocarbon gas and the combustion-supporting gas; a dilution section located on the secondary side of the combustion section; a catalyst section located on the secondary side of the dilution section and including a catalyst; The catalyst section includes a catalyst housing pipe that houses the catalyst, the dilution section and the combustion section are installed on the primary side of the catalyst housing pipe so as to be movable in accordance with thermal expansion or thermal contraction of the catalyst housing pipe, a carburizing gas generator that generates a carburizing gas containing carbon monoxide gas and hydrogen gas by reacting the combustion gas that has passed through the dilution section with the heated catalyst in the catalyst section.

4. 4. A carburizing gas generator according to claim 3, wherein flanges are provided at the top and bottom of the catalyst housing pipe, the dilution section and the combustion section are installed on the flanges provided at the top, and the dilution section and the combustion section are installed so as to be movable up and down in response to thermal expansion and contraction of the catalyst housing pipe.

5. 5. The carburizing gas generator according to claim 4, wherein a lateral displacement prevention guide is provided around the flange portion to restrict lateral displacement of the dilution portion relative to the catalyst portion.

6. The dilution section a first gas flow passage communicating with the combustion chamber; one or more third gas supply paths that supply a hydrocarbon-based gas to the first gas flow path; one or more fourth gas supply paths for supplying an inert gas to the first gas flow path; The carburizing gas generator according to any one of claims 1 to 5.

7. Further, a reforming section is provided between the combustion section and the dilution section, 7. The carburizing gas generator according to claim 6, wherein the reforming section is located between the combustion chamber and the first gas flow path, includes a second gas flow path that communicates with the combustion chamber and the first gas flow path, and reforms a portion of the combustion gas into carbon monoxide gas and hydrogen gas.

8. 8. The carburizing gas generator according to claim 7, wherein the reforming section includes a dispersion plate for dispersing the flow of the reformed combustion gas.

Images