Exhaust gas combustion equipment for degreasing furnaces and degreasing systems

Abstract

To provide an exhaust burner for degreasing furnaces that is excellent in all of power consumption, space, production cost, and running cost.SOLUTION: In a catalyst installation area 31c of a burner, disposed are catalysts including platinum on porous alumina ceramic. The catalysts are laid over a cylindrical housing made of a metal net, forming layers. For example, they are disposed at intervals over a plurality of stages.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas combustion device used in a degreasing furnace that degreases objects such as ceramic materials. [Background technology]

[0002] Conventionally, atmospheric gas degreasing furnaces or superheated steam degreasing furnaces have been used in the degreasing process, in which workpieces such as metals and ceramics are heat-treated to remove binder components (organic substances) from the workpieces.

[0003] In this degreasing process, the binder is decomposed and removed by heating the material being treated, but the exhaust gases generated during this process contain VOCs (volatile organic compounds). To prevent these from being released directly into the atmosphere, an exhaust gas combustion device is attached to the degreasing furnace and used to burn the exhaust gases.

[0004] The above-mentioned exhaust gas combustion devices include a direct combustion system in which exhaust gas is directly heated and burned, and a catalytic combustion system in which a catalyst is used to decompose (burn) exhaust gas (see Patent Document 1).

[0005] However, in the case of the direct combustion method, the degreasing process takes several tens of hours, and because it must be heated to about 800°C, the temperature at which VOCs burn, the power consumption of the exhaust gas combustion equipment operating during that time is extremely high. For this reason, it is difficult for direct combustion type exhaust gas combustion equipment to fully meet the demand for reduced power consumption that is being demanded of manufacturing equipment in general in line with recent carbon neutral initiatives.

[0006] Furthermore, in the case of the direct combustion method, the principle of heating exhaust gas with a heater increases the number of parts, and sufficient space for combustion is required, making the exhaust gas combustion device and therefore the entire degreasing furnace large.

[0007] On the other hand, in the case of catalytic combustion, if the catalyst is heated to about 400°C, VOCs will burn through spontaneous combustion (catalytic) action, which makes it possible to reduce power consumption compared to direct combustion methods.

[0008] However, if the exhaust gas concentration is too high, spontaneous combustion will cause the catalyst temperature to rise and lead to thermal degradation, so the exhaust gas concentration must be reduced (diluted) before use, which requires a large amount of dilution gas, which increases the overall gas flow rate and running costs.

[0009] In recent years, there are degreasing furnaces that use superheated steam to shorten the degreasing time, but because the exhaust gas concentration increases as the degreasing process time is shortened, exhaust gas combustion equipment ultimately has to adopt either a direct combustion method or a catalytic combustion method with large amounts of gas dilution, which makes the above-mentioned problems more pronounced and becomes a hindrance to superheated steam type degreasing furnaces. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 8-194093 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention is intended to solve all of the above problems at once, and is a groundbreaking invention that overturns the common knowledge in the technical field that catalytic combustion type exhaust gas combustion devices require dilution. [Means for solving the problem]

[0012] That is, the exhaust gas combustion device for a degreasing furnace according to the present invention burns the exhaust gas generated in the degreasing furnace using a catalyst, and is characterized in that the catalyst is a porous alumina ceramic containing platinum.

[0013] This catalyst shows almost no thermal degradation even at high temperatures (for example, 1100°C), making it possible to combust the highly concentrated exhaust gas generated in the degreasing process without diluting it. Furthermore, when exhaust gas containing organic compounds is decomposed using this catalyst, heat of decomposition of approximately 100°C is generated at a gas concentration of 100 ppm. Even when treating substances that are difficult to oxidize at low temperatures, this reaction heat can be absorbed by the porous alumina ceramic body to raise the catalyst temperature and decompose the gas. This means that there is no need to actively raise the catalyst temperature, and exhaust gas can be treated while maintaining a relatively low temperature (200-400°C), reducing power consumption.

[0014] This eliminates the drawback of conventional catalytic combustion type exhaust gas combustion devices, which require large amounts of dilution gas, and reduces the amount of gas used by the entire device, thereby reducing running costs. Furthermore, the advantages of the catalytic combustion system over the direct combustion system, such as low power consumption, space saving, and low manufacturing costs, can be further enhanced. Furthermore, this effect becomes more pronounced when combined with superheated steam degreasing. [Effects of the Invention]

[0015] The above-described configuration eliminates the drawbacks of conventional catalytic combustion type exhaust gas combustion devices and makes use of their advantages to provide an exhaust gas combustion device for a degreasing furnace that is excellent in terms of power consumption, space, manufacturing costs, running costs, etc. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram of an entire degreasing system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a front view of the exhaust gas combustion device according to the embodiment. [Figure 3] FIG. 2 is a perspective view showing the internal structure of the exhaust gas combustion device according to the embodiment. [Figure 4] FIG. 2 is a perspective view showing a catalyst container in the same embodiment. [Figure 5] 2 is a front view of the internal structure of the exhaust gas combustion device according to the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] As shown in a schematic overall view in Figure 1, the degreasing system 100 of this embodiment comprises a degreasing furnace 1 in which the object to be treated is housed, a superheated steam generator 2 that supplies superheated steam, which is a degreasing gas, into the degreasing furnace 1, and an exhaust gas combustion device 3 that introduces and combusts exhaust gas generated from the object to be treated W during the degreasing process using the superheated steam. The following description will focus on the exhaust gas combustion device 3.

[0019] As shown in Figures 2 and 3, this exhaust gas combustion device 3 includes a cylindrical combustor 31, a heater 32 that heats the inside of this combustor 31, and a catalyst 33 housed in the combustor 31.

[0020] Each part will be described in detail. The combustor 31 includes a cylindrical portion 311 and flange portions 312 that close both ends of the cylindrical portion 311. An inlet port 31a through which exhaust gas is introduced is provided on the side surface at one end of the cylindrical portion 311, and an outlet port 31b through which exhaust gas (treated gas) that has been combusted through the cylindrical portion 311 is discharged is provided on the side surface at the other end. The combustor 31 is disposed upright with the inlet port 31a at the lower end and the outlet port 31b at the upper end.

[0021] 3, two catalyst installation areas 31c are set apart from each other along the axial direction between the inlet port 31a and the outlet port 31b in the cylindrical portion 311. A catalyst container 34 that houses the catalyst 33 is attached to each catalyst installation area 31c (note that the catalyst 33 and the catalyst container 34 are omitted from FIG. 3). As shown in Figure 4, this catalyst container 34 is cylindrical with one end surface (top end surface) open, and is made of a material (here, a metal mesh) with many holes of a diameter that allows gas to pass through but retains the catalyst, and is arranged by fitting it to the inner surface of the cylindrical portion 311.

[0022] The heater 32 here is a flexible linear heater that is installed in a spiral shape wound around the upper end and / or lower end of each catalyst installation area 31c with a gap therebetween.

[0023] The catalyst 33 is a particulate (here, spherical) catalyst in which platinum, the catalyst body, is supported on porous alumina ceramics, and has the following specifications. Material: Alumina Main component: Al2O3 90% or more Bulk density: 1.52g / cm 3 Water absorption rate: 35±5% Apparent porosity: 55±5% Specific surface area: 8m 3 / g Maximum operating temperature: 1100℃ Ball diameter: 5mm As shown in FIG. 5, the catalyst 33 is spread over each of the catalyst containers 34 so as to form a layer 33A having a thickness of 20 mm to 25 mm.

[0024] Therefore, with the exhaust gas combustion device 3 configured as above, the maximum operating temperature of the catalyst 33 is extremely high (1100°C in this case), so even if the catalyst 33 becomes hotter than the heating temperature of the heater 32 (400°C in this case) due to the spontaneous combustion of the exhaust gas, it can maintain its performance without thermal degradation. Therefore, even if the exhaust gas discharged in the degreasing process has a high VOC concentration, for example, exceeding 10000 ppm, it can be burned without dilution. This can easily overcome the drawbacks of the conventional catalytic combustion system, namely, the need for a large amount of dilution gas and the resulting increase in running costs.

[0025] In particular, in this embodiment, degreasing is performed using superheated steam to shorten the degreasing time, which tends to result in higher exhaust gas concentrations. Conventionally, this has required the use of a large combustor using a direct combustion method, or a catalytic combustion method using a large amount of dilution gas. However, the exhaust gas combustion device of this embodiment uses a catalytic combustion method, but does not require dilution gas, and can ensure the advantages of compact size and low running costs. Therefore, when combined with superheated steam degreasing, the effect is particularly remarkable.

[0026] Furthermore, because the catalytic combustion method can be adopted without difficulty in this way, it is possible to dramatically reduce power consumption during operation compared to exhaust gas combustion devices that use a direct combustion method, and it is also possible to significantly reduce space and manufacturing costs.

[0027] According to calculations made by the inventors, it has been confirmed that extremely significant benefits can be achieved, such as power consumption being reduced by approximately 10 to 20%, space being reduced by approximately 80%, and manufacturing costs being reduced by approximately 20%, compared to a direct combustion type exhaust gas combustion device 3.

[0028] Furthermore, when there is only one catalyst layer, the exhaust gas tends to concentrate only in areas where it flows easily during combustion, and catalytic combustion occurs only in the catalyst 33 that is in contact with that gas path, making it difficult to further improve combustion efficiency. However, in this embodiment, by isolating catalyst layers 33A and providing a space layer P (shown in Figure 3) between them, gas diffusion occurs in this space layer P, and an exhaust gas path is formed evenly throughout the entire catalyst layer 33A, allowing catalytic combustion to occur efficiently throughout the entire catalyst 33.

[0029] This effect is also enhanced by the provision of exhaust gas introduction port 31a on the side peripheral surface of combustor 31. That is, because exhaust gas is introduced from a direction different from (perpendicular to) the gas flow inside combustor 31, turbulence is likely to occur during introduction, which causes exhaust gas to flow evenly throughout first-stage catalyst layer 33A, thereby promoting efficient catalytic combustion.

[0030] The features of the exhaust gas combustion device 3 described above can be summarized as follows: (1) This exhaust gas combustion device 3 for a degreasing furnace burns the exhaust gas generated in the degreasing furnace 1 using a catalyst 33, and is characterized in that the catalyst 33 is a porous alumina ceramic containing platinum. With this arrangement, it is possible to provide an exhaust gas combustion device 3 for a degreasing furnace that is excellent in terms of power consumption, space, manufacturing costs, running costs, and the like, as described above. (2) The catalyst 33 is in the form of particles, and the catalyst 33 is spread in layers in a catalyst container 34 inside the combustor 31 through which the exhaust gas passes. The catalyst container 34 is a metal mesh. In this case, the exhaust gas is brought into contact with the catalyst 33 reliably, and therefore the combustion efficiency can be improved. (3) A catalyst container is provided, which is made of a material having a plurality of holes with a diameter that allows exhaust gas to pass through but retains the catalyst, and the catalyst is laid out in layers inside the catalyst container. (4) In the combustor 31, the catalyst layers 33A are laid out in layers and provided in a plurality of stages at intervals. With this structure, the exhaust gas diffuses in the spaces between the catalyst layers 33A, and an exhaust gas path is formed evenly throughout the catalyst layer 33A, so that catalytic combustion can be carried out more efficiently throughout the catalyst 33 as a whole. (5) In order to improve catalytic efficiency, the bulk density of the catalyst 33 is 0.5 g / cm 3 ~3g / cm 3 is preferable, and more preferably 1 g / cm 3 ~2g / cm 3 is good. (6) The apparent porosity of the catalyst 33 is preferably 30% to 60%, and more preferably 50% to 60%. (7) The pore diameter of the catalyst 33 is preferably 0.1 μm to 5 μm, and more preferably 1 μm to 3 μm. (8) The diameter of the catalyst 33 is preferably 1 mm to 10 mm, and more preferably 3 mm to 7 mm. (9) The exhaust gas combustion device for a degreasing furnace burns the exhaust gas generated in the degreasing furnace using a catalyst. The catalyst is granular and is laid out in layers inside a combustor through which the exhaust gas passes. The layered catalyst layers are arranged in multiple stages at intervals inside the combustor. In this case, the exhaust gas diffuses in the spaces between the catalyst layers 33A, and an exhaust gas path is formed evenly throughout the catalyst layer 33A, so that catalytic combustion can be carried out more efficiently throughout the catalyst 33 as a whole. (10) If the degreasing furnace 1 degreases the treatment object W using superheated steam, the effect of this embodiment becomes more pronounced.

[0031] The present invention is not limited to the above-described embodiment. For example, the catalyst is not limited to a spherical shape, and may be of an irregular shape as long as there are gaps between them when laid out. The number of catalyst layers is not limited to two, and may be one layer or three or more layers. The degreasing gas is not limited to superheated steam, and N2 gas may also be used. Multiple sets of the exhaust gas combustion device 3 of the present invention may be connected together for use. The shape of the exhaust gas combustion device is not limited to a cylindrical type, and may be a block type or the like. Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the spirit of the present invention. [Explanation of symbols]

[0032] 100···Degreasing System 3. Exhaust gas combustion device 31. Combustor 33. Catalyst 33A...Catalyst layer

Claims

1. The exhaust gas generated in the degreasing furnace is combusted using a catalyst, and the catalyst is a porous alumina ceramic containing platinum, The catalyst is in a granular form, and the catalyst is spread in layers inside a combustor through which exhaust gas passes, The exhaust gas combustion device for a degreasing furnace is characterized in that catalyst layers are laid out in layers within the combustor, and multiple stages are provided with space layers separating each other, and the catalysts in the multiple stages are all porous alumina ceramics containing platinum, and the space layers have a gas diffusion effect.

2. Further comprising an exhaust gas inlet port for introducing exhaust gas from the degreasing furnace, 2. The exhaust gas combustion device for a degreasing furnace according to claim 1, wherein the exhaust gas introduction port is provided on a side peripheral surface of the exhaust gas combustion device, and turbulence is generated by introducing the exhaust gas from a direction different from the flow direction of the exhaust gas within the exhaust gas combustion device.

3. 2. An exhaust gas combustion device for a degreasing furnace as described in claim 1, which has a catalyst container formed of a material with a plurality of holes having a diameter that allows exhaust gas to pass through but retains the catalyst, and the catalyst is spread in layers inside the catalyst container.

4. 4. The exhaust gas combustion device for a degreasing furnace according to claim 1, wherein the bulk density of said catalyst is 0.5 g / cm<3> to 3 g / cm<3>.

5. 5. The exhaust gas combustion device for a degreasing furnace according to claim 1, wherein the apparent porosity of said catalyst is 30% to 60%.

6. 6. The exhaust gas combustion device for a degreasing furnace according to claim 1, wherein the catalyst has a pore size of 0.1 μm to 5 μm.

7. 7. The exhaust gas combustion device for a degreasing furnace according to claim 1, wherein the catalyst has a diameter of 1 mm to 10 mm.

8. An exhaust gas combustion device for a degreasing furnace that combusts exhaust gas generated in a superheated steam degreasing furnace using a catalyst, A plurality of catalyst layers each made of porous alumina ceramics supporting granular platinum; a heater installed at the upper end and / or the lower end of each of the areas where the plurality of catalyst layers are installed.

9. A degreasing system comprising a degreasing furnace and the exhaust gas combustion device for a degreasing furnace according to any one of claims 1 to 8.

10. 10. The degreasing system according to claim 9, wherein the degreasing furnace degreases the object to be treated using superheated steam.

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