Integrated catalyst basket of ammoxidation furnace
By adopting the catalytic basket body with a hole structure and a U-shaped expansion structure in the ammonia oxidation furnace, the deformation and sealing problems of the catalyst basket under high temperature environment are solved, efficient catalytic oxidation and safe operation are achieved, and the service life of the equipment is extended.
Patent Information
- Application Number
- CN202422239414.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-12
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2034-09-12
AI Technical Summary
The existing ammonia oxidation furnace catalyst basket is prone to deformity and has poor sealing properties under high temperature environments, resulting in platinum mesh falling off, super high ammonium salt and explosion risk, and mismatched thermal expansion leads to deformation of the connector, affecting the sealing property and catalytic oxidation efficiency.
The catalyst basket body with a hole structure and an annular vertical plate are connected to the ammonia oxidation furnace cylinder in combination with a U-shaped expansion structure. The high-temperature resistant nickel-based alloy material and an N-shaped platinum mesh support table are used to set up expansion joints and platinum mesh compression blocks to absorb thermal expansion displacement and ensure sealing and catalytic efficiency.
It improves the sealing of the catalyst basket, avoids the phenomenon of platinum mesh falling off and bypassing, extends the equipment life, reduces maintenance costs, and ensures catalytic oxidation efficiency and safety.
Smart Images
Figure CN223069477U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to an integrated catalyst basket for an ammonia oxidation furnace, belonging to the technical field of ammonia oxidation furnace equipment in the nitric acid production process. Background Art
[0002] An important step in the production of nitric acid or caprolactam is the catalytic oxidation of ammonia, and the catalytic oxidation reaction is carried out on a platinum-rhodium catalyst mesh inside the ammonia oxidation furnace. The catalyst basket plays an indispensable role as a bracket for the catalyst mesh. In addition, the catalyst basket contains and supports the Raschig rings for the platinum-rhodium catalyst mesh or the catalyst for treating N2O.
[0003] The existing catalyst basket includes a special grab-type orifice plate, a support ring, a platinum mesh support table, a support plate, screws and washers. It has the following defects during operation:
[0004] 1) During the operation of the ammonia oxidation furnace, the ambient temperature of the catalyst basket is 850 - 870 °C. In such a high-temperature environment, the material of the catalyst basket will creep, the strength will decrease, and eventually deformation will occur.
[0005] 2) Due to the high-temperature environment, the platinum mesh support table of the catalyst basket is prone to deformation, resulting in the platinum mesh falling off and being damaged. As a result, some gaseous ammonia directly enters the next process without passing through the platinum mesh, causing the ammonium salt to be too high.
[0006] 3) Due to the poor sealing of the catalyst basket, some ammonia-air mixture directly enters the reaction product through the gap without undergoing catalytic oxidation reaction, reacts with nitric acid and nitrite to form ammonium salt, thereby causing the ammonium salt to be too high. A large amount of ammonium salt will accumulate on the blades of the nitric oxide compressor and is prone to explosion when encountering an open flame or friction.
[0007] 4) During the startup process of the ammonia oxidation furnace, due to the increase in ambient temperature, the catalyst basket will expand thermally upward. In order to avoid the phenomenon of flue gas short-circuit, the catalyst basket is connected to the ammonia oxidation furnace cylinder through a connecting piece. The thermal expansion coefficients of the cylinder and the catalyst basket are different, which easily causes the connecting piece to deform and ultimately affects the sealing performance of the catalyst basket.
[0008] 5) The catalyst basket for containing Raschig rings or emission reduction catalyst is a porous plate structure and is prone to cracks and even cracking in a high-temperature environment, resulting in the falling off of Raschig rings or emission reduction catalyst. Content of the Utility Model
[0009] The purpose of the utility model is to provide an integrated catalyst basket for an ammonia oxidation furnace to solve the technical problem that the connecting piece of the catalyst basket in the prior art is prone to heat deformation, resulting in a decrease in the sealing performance of the catalyst basket.
[0010] The utility model adopts the following technical solution: an integrated catalyst basket for an ammonia oxidation furnace, which comprises a catalyst basket body and an annular vertical plate fixed on the outer periphery of the catalyst basket body. The catalyst basket body is a horizontally arranged porous structure. The upper end surface of the annular vertical plate is fixedly connected with a platinum mesh support platform in a ring structure. A platinum mesh pressing block is arranged above the platinum mesh support platform. The outer side of the platinum mesh support platform is fixedly connected with a U-shaped expansion structure. The U-shaped expansion structure comprises an inner ring and an outer ring integrally connected. The cross-section is U-shaped after the inner ring and the outer ring are integrally connected. The end of the inner ring is fixedly connected with the platinum mesh support platform, and the end of the outer ring is fixedly connected with the cylinder body of the ammonia oxidation furnace.
[0011] The cross-section of the platinum mesh support platform is an N-shaped structure. The top of the N-shaped structure has an annular plane. The inner side of the N-shaped structure is fixedly connected with the annular vertical plate, and the outer side of the N-shaped structure is fixedly connected with the inner ring of the U-shaped expansion structure.
[0012] Expansion joints are arranged on the annular plane of the platinum mesh support platform. The expansion joints are spaced apart in the radial direction of the annular plane. Each expansion joint extends from the inner side of the annular plane to the middle.
[0013] The platinum mesh pressing block is formed by butting two or more arc-shaped blocks. Adjacent arc-shaped blocks are fixedly connected by U-shaped connecting pieces.
[0014] The platinum mesh pressing block is made of a high-temperature resistant 309 material.
[0015] The catalyst basket body adopts a grid structure.
[0016] The catalyst basket body is formed into a circular structure by connecting 4 structures through bolts.
[0017] A support member is connected to the bottom of the catalyst basket body.
[0018] Both the catalyst basket body and the platinum mesh support platform are made of a selected high-temperature resistant nickel-based alloy material.
[0019] The beneficial effect of the utility model is that: by arranging a U-shaped expansion structure between the catalyst basket and the cylinder body of the ammonia oxidation furnace, the inner ring of the U-shaped expansion structure is fixedly connected with the platinum mesh support platform, and the end of the outer ring is fixedly connected with the cylinder body of the ammonia oxidation furnace. The U-shaped expansion structure not only plays a role in connecting the catalyst basket and the cylinder body of the ammonia oxidation furnace, but also can absorb the displacement caused by thermal expansion on both the inner and outer sides. The U-shaped expansion structure is similar to the wave on the expansion joint and is not easily damaged after absorbing the displacement difference caused by thermal expansion. Therefore, the sealing performance of the outer periphery of the catalyst basket is ensured, preventing the mixer from passing through the gap between the outer periphery of the catalyst basket and the cylinder body of the ammonia oxidation furnace, ensuring that all the ammonia-air mixture passes through the platinum mesh for catalytic oxidation, improving the catalytic oxidation efficiency, and preventing bypass phenomena.
[0020] Preferably, the cross-section of the platinum mesh support platform is an N-shaped structure, which can cut off the local part with stress concentration, reduce or eliminate stress concentration, extend the service life of the material, and further avoid the bypass phenomenon of the mixer.
[0021] Preferably, the expansion joint on the platinum mesh support platform can absorb the expansion amount of the platinum mesh support platform in the axial direction.
[0022] Preferably, in order to facilitate the replacement of the platinum mesh, the platinum mesh pressing block is divided into multiple arc-shaped blocks, and the adjacent arc-shaped blocks are connected by U-shaped connecting pieces to form an integral annular platinum mesh pressing block.
[0023] Preferably, the platinum mesh adopts a grid structure, which has high supporting force and durability, can withstand large pressure and weight, and can reduce the flue gas resistance.
[0024] Preferably, the catalyst basket body is placed on the coil pipe through the support, and the setting of multiple supports ensures the flatness of the catalyst basket body and makes the support of the catalyst basket more stable.
[0025] Preferably, both the catalyst basket body and the platinum mesh support platform are made of high-temperature-resistant nickel-based alloy materials, which are not easily oxidized during long-term use and can extend the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 is the overall structural schematic diagram of an integrated catalyst basket of an ammonia oxidation furnace according to an embodiment of the present invention;
[0027] Figure 2 is Figure 1 the partial view of the installation of the integrated catalyst basket of the ammonia oxidation furnace in the ammonia oxidation furnace in
[0028] Figure 3 is Figure 1 the partial view of the annular plane of the platinum mesh support platform in
[0029] Figure 4 is Figure 1 the partial schematic diagram of the platinum mesh pressing block in
[0030] Figure 5 is Figure 1 the partial top view of the platinum mesh pressing block in
[0031] Figure 6 is Figure 1 the schematic diagram of the catalyst basket body in
[0032] In the figure: 1 - catalyst frame body, 1.1 - support member, 2 - annular vertical plate, 3 - platinum mesh support platform, 3.1 - annular plane, 3.2 - expansion joint, 4 - platinum mesh pressing block, 4.1 - arc-shaped block, 4.2 - U-shaped connecting member, 4.3 - handle, 5 - U-shaped expansion structure, 5.1 - inner ring, 5.2 - outer ring, 6 - ammonia oxidation furnace cylinder body, 7 - platinum mesh assembly, 8 - coil pipe. Detailed implementation mode
[0033] The present utility model will be described in detail below in conjunction with the accompanying drawings and specific embodiments.
[0034] As Figures 1 to 6 shown, an integrated catalyst basket of an ammonia oxidation furnace according to an embodiment of the present utility model includes a catalyst frame body 1 and an annular vertical plate 2 fixed to the outer periphery of the catalyst basket body 1. The catalyst frame body 1 is a horizontally arranged porous structure. An annular platinum mesh support platform 3 is fixedly connected to the upper end surface of the annular vertical plate 2. A platinum mesh pressing block 4 is arranged above the platinum mesh support platform 3. It is characterized in that: a U-shaped expansion structure 5 is fixedly connected to the outside of the platinum mesh support platform 3. The U-shaped expansion structure 5 includes an inner ring 5.1 and an outer ring 5.2 that are integrally connected. After the inner ring 5.1 and the outer ring 5.2 are integrally connected, the cross-section is U-shaped. The end of the inner ring 5.1 is fixedly connected to the platinum mesh support platform 3, and the end of the outer ring 5.1 is fixedly connected to the ammonia oxidation furnace cylinder body 6.
[0035] Both the catalyst basket body 1 and the platinum mesh support platform 3 are made of a selected high-temperature resistant nickel-based alloy material. The cross-section of the platinum mesh support platform 3 is an N-shaped structure. The top of the N-shaped structure has an annular plane 3.1. The inner side of the N-shaped structure is fixedly connected to the annular vertical plate 2, and the outer side of the N-shaped structure is fixedly connected to the inner ring 5.1 of the U-shaped expansion structure 5. Expansion joints 3.2 are arranged on the annular plane 3.1 of the platinum mesh support platform. The expansion joints 3.2 are spaced apart in the radial direction of the annular plane 3.1, and each expansion joint extends from the inner side of the annular plane 3.1 to the middle.
[0036] The platinum mesh pressing block 4 is formed by butting two or more arc-shaped blocks 4.1. Adjacent arc-shaped blocks 4.1 are fixedly connected through a U-shaped connecting member 4.2. In this embodiment, there are 12 arc-shaped blocks 4.1 in total, and the arc-shaped blocks 4.1 are connected together to form an annular platinum mesh pressing block 4. The platinum mesh pressing block 4 is made of a 309 high-temperature resistant material.
[0037] The catalyst basket body 1 adopts a grid structure, and the catalyst basket body 1 is formed into a circular structure by connecting 4 structures through bolts. A support member 1.1 is connected to the bottom of the catalyst basket body 1.
[0038] In this embodiment, the catalyst basket for containing Raschig rings or emission reduction catalysts is made of a heat-resistant nickel-based alloy material, which can extend the service life of the material. The catalyst basket body 1 adopts a grid structure, and the grid structure is a hexagon formed by splicing grid plates at a certain distance (40 mm is adopted in this embodiment). Compared with the orifice plate structure, this structure endows the grid with high supporting force and durability, can withstand greater pressure and weight, and reduces the flue gas resistance. This structure can absorb its own thermal expansion amount and is not prone to cracks. Therefore, the catalyst basket body 1 in this embodiment can reduce the flue gas resistance and has a long service life. Considering that the catalyst basket needs to be moved if there is a maintenance task on site, the catalyst basket body 1 is divided into four structures, and the four structures are fixedly connected by bolts.
[0039] In addition to using a heat-resistant nickel-based alloy material, the platinum mesh support platform 3 adopts an N-shaped structure to consider eliminating thermal stress. Since the flue gas temperature at the platinum mesh support platform 3 in the ammonia oxidation furnace is 850 - 870 °C, if the platinum mesh support platform is made of square steel, there will be local stress concentration in the high-temperature environment, resulting in a decrease in the hardness and toughness of the material, and the material will deform or even crack. By adopting the N-shaped platinum mesh support platform in this embodiment, the local part with stress concentration can be cut off, which can reduce or eliminate stress concentration and extend the service life of the material. In addition, several expansion joints are arranged on the platinum mesh support platform 3, which can absorb its axial expansion amount.
[0040] The material of the platinum mesh pressing block 4 is selected as heat-resistant 309 material. To facilitate the replacement of the platinum mesh, the platinum mesh pressing block is divided into 12 arc-shaped blocks 4.1, and the adjacent arc-shaped blocks are connected by U-shaped connectors 4.2 to form an integral annular platinum mesh pressing block, so that the arc-shaped blocks are not prone to slipping. Each arc-shaped block is respectively provided with two handles 4.3. The U-shaped connector 4.2 is made of round steel, and a ceramic fiber pad is laid between the platinum mesh pressing block 4 and the platinum mesh assembly 7. The platinum mesh assembly 7 is fixed between the platinum mesh pressing block 4 and the platinum mesh support platform 3.
[0041] The U-shaped expansion structure 5 is used to connect the ammonia oxidation furnace cylinder body 6 and the platinum mesh support platform 3. The U-shaped expansion structure 5 is made of a heat-resistant nickel-based alloy material. According to the actual situation, the thermal expansion amounts of the catalyst basket and the ammonia oxidation furnace are pre-calculated, and then the U-shaped expansion structure is designed. The U-shaped expansion structure 5 is equivalent to the wave on the expansion joint and can absorb the displacement amounts brought by thermal expansion on both the inside and outside. The lower cylinder walls of the catalyst basket and the ammonia oxidation furnace are affected by high-temperature flue gas. In the longitudinal direction, the catalyst basket and the lower cylinder wall move upward. Due to different positions and materials, the displacement amounts on both sides are different. The U-shaped expansion structure not only plays a role in connecting the catalyst basket and the ammonia oxidation furnace cylinder body, but also can absorb the displacement difference on both sides. In the axial direction, the expansion displacement amounts of the catalyst basket and the lower cylinder wall of the ammonia oxidation furnace are also different, and the U-shaped expansion structure can also absorb the displacement difference.
[0042] Generally speaking, the utility model has the following advantages: (1) The utility model has good circumferential sealing performance of the catalyst basket, which can ensure that all ammonia-air mixtures pass through the platinum mesh for catalytic oxidation, improve the catalytic oxidation efficiency, and prevent bypass phenomenon; (2) The utility model absorbs thermal expansion through the platinum mesh support platform with an N-shaped structure and a U-shaped expansion structure, reduces thermal stress, reduces the damage of materials in high-temperature environments, and extends the service life of the catalyst basket; (3) The utility model can meet the functions of installing the platinum mesh and filling the N2O reduction catalyst; (4) The utility model has a simple structure and uses less materials, saving manufacturing costs; (5) The utility model can reduce the system shutdown maintenance time and reduce the maintenance cost; (6) The utility model selects appropriate materials and is not easily oxidized at high temperature during long-term use.
[0043] The above embodiments are preferred embodiments of the utility model. Without departing from the spirit and scope of the utility model, various changes and improvements will occur to the utility model, and these changes and improvements all fall within the scope of the utility model claimed.
Claims
1. An integrated catalyst basket for an ammonia oxidation furnace, which comprises a catalyst basket body and an annular vertical plate fixed to the outer periphery of the catalyst basket body. The catalyst basket body is a horizontally arranged porous structure. An annular platinum mesh support platform is fixedly connected to the upper end surface of the annular vertical plate. A platinum mesh pressing block is arranged above the platinum mesh support platform, and it is characterized in that: A U-shaped expansion structure is fixedly connected to the outside of the platinum mesh support platform. The U-shaped expansion structure includes an inner ring and an outer ring that are integrally connected. After the inner ring and the outer ring are integrally connected, the cross-section is U-shaped. The end of the inner ring is fixedly connected to the platinum mesh support platform, and the end of the outer ring is fixedly connected to the ammonia oxidation furnace cylinder body.
2. The integrated catalyst basket of an ammonia oxidation furnace according to claim 1, characterized in that: The cross-section of the platinum mesh support platform is an N-shaped structure. The top of the N-shaped structure has an annular plane. The inner side of the N-shaped structure is fixedly connected to the annular vertical plate, and the outer side of the N-shaped structure is fixedly connected to the inner ring of the U-shaped expansion structure.
3. The integrated catalyst basket of an ammonia oxidation furnace according to claim 2, wherein: Expansion joints are arranged on the annular plane of the platinum mesh support platform. The expansion joints are spaced apart in the radial direction of the annular plane, and each expansion joint extends from the inner side of the annular plane to the middle.
4. The integrated catalyst basket of the ammonia oxidation furnace according to claim 1, wherein: The platinum mesh pressing block is formed by docking two or more arc-shaped blocks, and adjacent arc-shaped blocks are fixedly connected by U-shaped connecting pieces.
5. The integrated catalyst basket of an ammonia oxidation furnace according to claim 1, characterized in that: The platinum mesh pressing block is made of a material that can withstand high temperatures of 309.
6. The integrated catalyst basket of an ammonia oxidation furnace according to claim 1, characterized in that: The catalyst basket body adopts a grid structure.
7. The integrated catalyst basket of an ammonia oxidation furnace according to claim 1, characterized in that: The catalyst basket body is formed into a circular structure by connecting 4 structures with bolts.
8. The integrated catalyst basket of an ammonia oxidation furnace according to claim 1, characterized in that: A support member is connected to the bottom of the catalyst basket body.
9. The integrated catalyst basket of an ammonia oxidation furnace according to claim 1, characterized in that: Both the catalyst basket body and the platinum mesh support platform are made of a selected high-temperature resistant nickel-based alloy material.