Fixing device for a segmentation element in a catalyst basket for bulk catalysts

Abstract

The invention relates to a fixing device for fastening a segmentation element to a gas-permeable bottom. The gas-permeable bottom can be part of a catalyst basket. The fixing device comprises a base, a stand and a holding device, wherein the stand is arranged on the base and a holding device is arranged on the stand. The holding device is arranged at least partially over the base and the holding device is designed to press a segmentation element against the base.

Description

[0001] 2023PF00176

[0002] 1

[0003] Fixing device for a segmentation element in a catalyst basket for bulk catalysts

[0004] The invention relates to a fixing device for a segmentation element in a segmented catalyst basket, and to a catalyst basket containing this fixing device. Fixed-bed reactors for gas reactions often contain bulk catalysts. The bulk catalysts are typically arranged in baskets. Such catalyst baskets have a basket wall and a gas-permeable bottom.

[0005] An example of the use of catalyst baskets with bulk material is in large-scale reactors for the production of nitric acid using the Ostwald process, in which ammonia is oxidized with oxygen. In the first step, a mixture of gaseous ammonia and oxygen is passed over a catalyst system with platinum-rhodium meshes at 800°C–930°C. Nitrous oxide (laughing gas) is produced as a byproduct. Since nitrous oxide has a high global warming potential in the Earth's atmosphere, there is an effort to reduce this as much as possible. To this end, the primary gas stream resulting from the catalyst system is brought into contact, in the direction of flow, with a bulk catalyst, also called a secondary catalyst, which decomposes the nitrous oxide produced into oxygen and nitrogen.

[0006] If the bulk catalyst is contained in a simple catalyst basket within the reactor, the material can move freely within this basket due to vibrations and thermal expansion during operation. This can lead to an inhomogeneous distribution of the bulk material within the catalyst basket. This, in turn, negatively affects the flow conditions in the reactor. To prevent the bulk material from migrating within the catalyst basket, the catalyst basket is segmented into individual sections using one or more segmentation elements. A segmentation element is preferably a sheet metal plate. Segmentation elements are preferably arranged vertically on the bottom of the catalyst basket. The bottom of the basket is gas-permeable and usually comprises one or more layers of mesh, a grid, a perforated sheet, or a combination thereof.Because the segmentation element also moves due to vibrations or thermal expansion during reactor operation, bulk catalyst can get under it, partially disrupting the segmentation and allowing the catalyst to migrate within the basket. This must be avoided.

[0007] Against this background, an object of the present invention was to provide a simple fastening device for a segmentation element on a gas-permeable base, in particular a basket base of a catalyst basket. 2023PF00176

[0008] 2

[0009] Furthermore, it is often necessary that the fastening device for a segmentation element be as resistant to corrosion as possible.

[0010] Another preferred objective was to provide a fixing device that is easy to attach and reliably holds the segmentation element in place on the gas-permeable floor. A further preferred objective of the invention was to provide a fixing device that does not damage either the gas-permeable floor or the segmentation element that is secured by the fixing device.

[0011] The problem is solved by a fixing device (1) for attaching a segmentation element (40) to a gas-permeable base (50), comprising a foot (10), a stand (20) and a holding device (30), wherein the stand is connected to the foot (10) and a holding device (30) is arranged on the stand (20), characterized in that the holding device (30) is arranged at least partially above the foot (10) and that the holding device (20) is designed to press a segmentation element (40) against the foot (10).

[0012] The solution according to the invention enables a particularly simple and reliable fixation of a segmentation element to a gas-permeable base, thus reducing the local accumulation of bulk catalyst. In particular, the gas-permeable base is hardly damaged, or not damaged at all, by the fixing device, preventing bulk catalyst from escaping the catalyst basket. In other words, bulk catalyst does not fall out of the basket base if the base remains intact while the segmentation element is fixed. Ultimately, the invention enables a more uniform distribution of bulk catalyst within a catalyst basket, which in turn can lead to more consistent flow conditions.

[0013] The invention relates to a fixing device. Such a fixing device within the scope of the invention can preferably be understood as a device suitable for attaching a segmentation element to a gas-permeable base. In particular, the fixing device secures a segmentation element standing vertically on a gas-permeable base by means of a positive-locking fastening. In one possible embodiment, the fixing device fastens a vertically standing segmentation sheet to the base. The segmentation element of the present invention can, for example, be an unperforated sheet, a perforated sheet, a grid, or a mesh. The segmentation element can, for example, be arranged in a ring shape on the gas-permeable base. If the segmentation element is a grid or mesh, the 2023PF00176

[0014] 3

[0015] The segmentation element comprises a support structure for the mesh or grid. The support structure can, for example, be a frame within which a grid or mesh is stretched or to which a grid or mesh is attached. The segmentation element can also be understood as a partition between at least two areas in a catalyst basket, wherein preferably at least one area contains bulk catalyst.

[0016] The gas-permeable base of the present invention can be a mesh, a grid, or a gas-permeable sheet, e.g., a perforated sheet. Preferably, the gas-permeable base is part of a catalyst basket. A catalyst basket comprises at least one basket wall that surrounds a volume and a gas-permeable base that limits, and in particular closes, the volume on one side of the basket. The term "closes" here means that the escape of solids is prevented, while gas can pass through the base. The basket wall of the catalyst basket can be gas-permeable or gas-impermeable. For example, the basket wall is gas-impermeable if it is formed from a solid sheet. Alternatively, the basket wall of the catalyst basket can be gas-permeable, e.g., if it comprises a perforated sheet or a grid. The gas-permeable base contains openings through which gas can pass.The gas-permeable base can optionally be positively or materially bonded to the wall of the catalyst basket. The material of the catalyst basket, or of the gas-permeable base and the catalyst wall, is preferably a material that is as corrosion-resistant as possible in an ammonia oxidation reactor. Preferably, the material of the catalyst basket and its components comprises or consists of steel. Suitable materials for the fixing device and the catalyst basket must withstand the conditions in an ammonia oxidation reactor during the process and are known to those skilled in the art. For example, nickel-chromium alloys (NiCrFe alloys) such as Inconel600 (material no. 2.4816), iron-chromium-aluminium alloys (FeCrAl alloys) such as those sold under the trade names Megapyr (material no. 1.4767) or Kanthai (e.g. Kanthai A-1: ​​22.00 wt.% Cr, 5.80 wt.%-%Al, balance Fe) are available or heat-resistant stainless steels are used, with nickel-chromium alloys proving to be particularly suitable.

[0017] The catalyst basket can preferably be designed as a single piece or in multiple pieces. If the catalyst basket is designed as a single piece, the bottom and the wall can be formed from a continuous mesh, grid, or perforated sheet.

[0018] The fixing device has a base, a stand, and a holding device. The base can be, for example, a sheet metal or a perforated metal sheet. 2023PF00176

[0019] 4

[0020] The foot serves several functions. Firstly, it acts as a base plate for the stand, to which it is connected. Secondly, it functions as a counterpart to the holding device, securing a segmentation element between the two. In other words, the holding device can press the segmentation element against the foot.

[0021] The stand preferably separates the foot from the holding device. The distance between the foot and the holding device is determined by the stand. Preferably, the distance between the foot and the holding device is flexibly adjustable via the stand. For this purpose, the stand can optionally have an adjustment mechanism. The adjustment mechanism preferably comprises a screw thread or a clamping device. In particular, the adjustment mechanism can be a screw thread with a lock nut. In a possible embodiment, the adjustment mechanism, as part of the stand, can move the holding device and the foot towards each other, so that an optional segmenting element is attached between the foot and the holding device. The stand is designed so that it can be inserted through a gas-permeable floor without damaging it.If the gas-permeable base comprises a mesh or grid, the stand is preferably designed to pass through the mesh or grid without damaging it, and in particular without cutting it. The stand is preferably a rod with a maximum diameter of 1–5 mm, particularly 2–3 mm. This ensures that the gas-permeable base is hardly damaged, or not damaged at all. Optionally, the stand can have a larger diameter in the area not designed to pass through a gas-permeable base.

[0022] The holding device is attached to the stand and prevents a segmentation element, in particular a segmentation plate, from moving away from or lifting off the gas-permeable base. The holding device can be, for example, a hook, a groove, or a clamp. The holding device is preferably designed to exert pressure on the base via a segmentation element.

[0023] The fixing device can optionally be designed as a single piece, so that the base, stand, and holding device are manufactured from one piece. In this case, the fixing device is a type of clamp. Preferably, the fixing device is designed as a multi-part device, such that one or more parts of the fixing device are dedicated components that together form the fixing device. For example, the fixing device can have a separate base that is connected to the stand. The base can be screwed, welded, riveted, or otherwise attached to the stand. 2023PF00176

[0024] 5

[0025] The base is preferably screwed or welded to the stand. The stand and the holding device can, for example, be made from a single piece or from multiple parts. It is particularly preferred that the holding device is connected to the stand via a screw connection.

[0026] A second aspect of the invention relates to a segmented catalyst basket for a bulk catalyst, wherein the catalyst basket has a gas-permeable base, one or more segmentation elements and a fixing device for attaching at least one segmentation element to the gas-permeable base, wherein the fixing device comprises a foot, a stand and a holding device, wherein the foot is arranged below the gas-permeable base, the stand is attached to the foot and the holding device is arranged, in particular attached, to the stand, characterized in that the holding device is arranged at least partially above the foot and the segmentation element is attached, in particular held, on the gas-permeable base.

[0027] The catalyst basket according to the invention enables improved segmentation of the bulk catalyst, thereby preventing the bulk catalyst from migrating from one segment to another and accumulating there during operation in the reactor.

[0028] A catalyst basket can be understood as a container comprising at least one basket wall and a gas-permeable base. The catalyst basket is capable of receiving and securely holding bulk catalyst. Optionally, the wall of the catalyst basket can be gas-permeable. In one possible embodiment, the entire catalyst basket is formed from one or more meshes or grids. It is also possible for the basket wall to be gas-impermeable. In this case, the basket wall contains or consists of a sheet metal component. The sheet metal component can be designed as a ring. The gas-permeable base can be positively or materially bonded to the basket wall.

[0029] The catalyst basket is segmented. Segmented here means that the volume of the catalyst basket is divided into at least two volume segments. The segments are arranged so that gas can flow through the catalyst basket. The gas can, in particular, be gas that is routed from the previous reaction stage in a reactor to a bulk catalyst. The catalyst basket is suitable for receiving bulk catalyst. The bulk material can, in particular, be granules, Raschig rings, or pellets. 2023PF00176

[0030] 6

[0031] The mean diameter of the bulk material catalyst is preferably in the range of 2–20 mm.

[0032] The catalyst basket is segmented by at least one segmentation element. The segmentation element of the present invention can, for example, be an unperforated sheet, a perforated sheet, a grid, or a mesh. If the segmentation element is a grid or mesh, it can include a support structure for the grid or mesh. The support structure can, for example, be a frame in which a grid or mesh is stretched. The segmentation element can preferably divide a catalyst basket into two or more segments. The number of possible segments is not further limited according to the invention and can be determined by a person skilled in the art to avoid local accumulation of bulk catalyst.

[0033] The catalyst basket contains a fixing device as described in the first aspect of the invention. The fixing device comprises a base, a stand, and a holding device. The base is arranged beneath the gas-permeable base. In particular, the base is located on the side of the gas-permeable base where there is no bulk catalyst material. In other words, the base of the fixing device is located outside the catalyst basket. Thus, the base is located on one side of the gas-permeable base, and the holding device attached to the stand is located on the other side of the gas-permeable base. This allows the holding device to press the segmenting element against the gas-permeable base and the base located beneath it.

[0034] The stand is guided through the gas-permeable floor and connected to the base. Preferably, the stand is guided through the gas-permeable floor in such a way that the floor is not damaged. Particularly if the gas-permeable floor is a mesh, the stand is preferably dimensioned so that the mesh is not torn.

[0035] The holding device is positioned at least partially above the base, and the segmentation element is attached to the gas-permeable base. In particular, the segmentation element is held on the gas-permeable base in such a way that no bulk catalyst can get between the segmentation element and the gas-permeable base. 2023PF00176

[0036] 7

[0037] The dimensions of the segmentation element are preferably adapted to the dimensions of the catalyst basket, so that an uneven distribution of bulk catalyst in the catalyst basket can be effectively avoided.

[0038] The dimensions of the fixing element are preferably adapted to the dimensions of the segmenting element in order to fulfill its function.

[0039] The invention is further illustrated below by means of examples, which, however, are not to be understood as limiting. It will be apparent to those skilled in the art that other equivalent means can be used in a similar manner instead of the features described here.

[0040] Figure 1 shows a fixing device (101) according to the invention for attaching a segmentation element (140) to a gas-permeable base (161). The fixing device has a base (10), a stand (120), and a holding device (130). The stand is connected to the base (110), and a holding device (130) is arranged on the stand (120). The holding device (130) is arranged at least partially above the base (110) and is designed to press a segmentation element (140) against the gas-permeable base and the base (110) located below it. In the present figure, the segmentation element (140) is designed as a segmentation plate. The segmentation element (140) separates two segments from each other, each of which contains bulk catalyst (150).

[0041] Figure 2A-D shows various examples of possible embodiments of the fixing device according to the invention. The embodiments of the foot, stand, and holding device from the figures shown can be freely combined. For example, the foot (210") from Figure 2B can also be combined with the stand (220") from Figure 2A.

[0042] Figure 2A shows a very simple version of the fixing device, in which a stand (220'), for example designed as a rod, is attached to a base (210'). The base can, for example, be made of sheet metal. The holding device (230') is attached to the stand (220') and is designed to hold a segmentation element. In the illustrated embodiment, the holding device (230') is shown as a simple hook. For example, the hook and the stand (220') can be formed from a continuous rod that is bent at one end. 2023PF00176

[0043] 8

[0044] Figure 2B shows an alternative fixing element. The base (210") is shown as a perforated sheet. The holding device (230") is designed as a groove. The stand (220") can, for example, be designed as a rod.

[0045] Figure 2C shows a fixing device in which the stand (220"') is made in two parts. The part of the stand that is attached to the base (210"') and the part of the stand to which the holding device (230"') is attached are positively connected to each other, in particular interlocked.

[0046] Figure 2D shows a fixing device in which a height-adjustable stand (220) is attached to the base (210). The base (210) can, for example, be screwed to the stand (220). The stand shown includes a screw connection with two threaded rods (222), a threaded sleeve (21), and a lock nut (23). A holding device (230) is attached to the height-adjustable stand (220). The height of the holding device can be adjusted via the screw connection (indicated by the double arrow). Additionally, pressure can be exerted on the segmenting element by the screw connection, clamping it between the holding device (230) and the base (210).

[0047] Figure 3 shows a segmented catalyst basket (302) according to the invention in a side cross-section in Figure 3A and of the same catalyst basket in a top view in Figure 3B. The segmented catalyst basket (302) comprises a basket wall (360) and a gas-permeable base (361). A segmentation element (340) is arranged in the segmented catalyst basket (302). In the illustrated embodiment, the segmentation element (340) is shown as an annular sheet. The segmentation element (340) is attached at one point to the gas-permeable base (361) by a fixing device (301). For illustrative purposes, the catalyst basket is filled with bulk catalyst (350), which is not part of the invention.

[0048] The right side of the segmentation element (340) is not secured by a fixing device, allowing the segmentation element to lift and bulk catalyst (350) to get underneath it. This catalyst then accumulates against the basket wall (360) of the catalyst basket (302). In contrast, the bulk catalyst cannot get underneath the segmentation element (340) on the left side because it is held in place on the gas-permeable base (361) by the fixing device (301).

[0049] Figure 3B shows a top view of the segmented catalyst basket (302). This basket is filled with bulk catalyst (350). A segmentation element (340) in the form of a segmentation sheet ring is located in the catalyst basket. This is separated by the sheet 2023PF00176.

[0050] 9

[0051] The shaped sleeve rests on the gas-permeable base. The segmentation element is attached to the gas-permeable base of the catalyst basket by a fixing device (301) in Figure 3B, although the gas-permeable base is not visible in this top view. Preferably, a segmentation element is attached to the gas-permeable base (361) with more than one fixing device. This effectively prevents uneven distribution of the bulk catalyst.

[0052] Figure 4 shows another embodiment of the segmented catalyst basket according to the invention. In the illustrated catalyst basket, the basket wall (460) and the gas-permeable base (461) are made of the same material. Here, the basket wall (460) is also gas-permeable. Preferably, the basket wall (460) and the gas-permeable base (461) are made of at least one layer of a metal mesh. An optional support structure (465) for the catalyst basket is shown here, in case the basket is too flexible to hold the bulk catalyst itself. The support structure (465) is designed to allow gas to flow through the catalyst basket. As in Figure 3, the fixing device comprises a foot (410), a stand (420), which is height-adjustable in Figure 4, and a holding device (430).

[0053] Preferably, the segmented catalyst basket is part of a reactor for ammonia oxidation. In such a reactor, ammonia is passed together with oxygen over catalytically active meshes (470) and reacted to form nitrogen oxides and water at a temperature in the range of approximately 800°C to 930°C. Nitrous oxide is present as a byproduct in the resulting gas mixture. The product mixture of nitrogen oxides, water, and nitrous oxide is passed over a bulk catalyst located in a segmented catalyst basket.

[0054] Reference symbol list

[0055]

[0056] 2023PF00176

[0057] 10

[0058]

Claims

2023PF00176 11 Claims 1. Fixing device (101) for attaching a segmentation element (140) to a gas-permeable base (161), comprising a foot (110), a stand (120) and a holding device (130), wherein the stand is arranged on the foot (110) and a holding device (130) is arranged on the stand (120), characterized in that the holding device (130) is arranged at least partially above the foot (110) and that the holding device (120) is designed to press a segmentation element (140) against the foot (110).

2. Fixing device according to claim 1, wherein the fixing device comprises a material selected from the group consisting of stainless steel, nickel-chromium-iron alloys, iron-chromium-aluminium alloys or one of these materials.

3. Fixing device according to one of claims 1 or 2, wherein the foot is designed as a bracket, a continuous plate or as a perforated plate.

4. Fixing device according to one of the preceding claims, wherein the stand comprises or consists of a rod or a sheet.

5. Fixing device according to one of the preceding claims, wherein the stand includes a thread to which the foot, the holding device or both are attached.

6. Fixing device according to one of the preceding claims, wherein the stand is designed in such a way that it can be guided through the gas-permeable base without damage and the diameter of the stand in the area adjacent to the foot is preferably no more than 5 mm.

7. Fixing device according to one of the preceding claims, wherein the stand comprises an adjustment mechanism that allows segmentation elements of different sizes to be attached to a gas-permeable base.

8. Fixing device according to any one of the preceding claims, wherein the adjustment mechanism comprises a screw connection or a clamping device.

9. Fixing device according to any one of the preceding claims, wherein the holding device comprises a hook or a clamp.

10. Segmented catalyst basket (302) for a bulk catalyst (350), 2023PF00176 12 wherein the catalyst basket (360) has a gas-permeable base (361), one or more segmentation elements and a fixing device (301) for attaching a segmentation element (340) to the gas-permeable base (361), wherein the fixing device comprises a foot (310), a stand (320) and a holding device (330), wherein the foot (310) is arranged under the gas-permeable base (361), the stand (320) is attached to the foot (310) and a holding device (330) is arranged on the stand (320), characterized in that the holding device (330) is arranged at least partially above the foot (310) and the segmentation element (340) is attached to the gas-permeable base.

11. Segmented catalyst basket according to claim 10, wherein the fixing device is designed according to any one of claims 1-9.

12. Segmented catalyst basket according to one of claims 10 or 11, wherein the segmentation element is designed in a ring shape.

13. Use of a segmented catalyst basket according to one of claims 10-12 in a reactor for ammonia oxidation.

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