Low-temperature denitration system based on self-heat generation

Abstract

This utility model discloses a low-temperature denitrification system based on self-exothermic heating, belonging to the field of flue gas denitrification technology. It includes a denitrification tower with an internal airflow distribution plate. Behind the airflow distribution plate are five catalyst layers and six ammonia injection grids, arranged alternately. A heat exchanger and a supplementary heat exchanger are installed at the inlet and outlet of the denitrification tower, respectively. A first connecting pipe connects the heat exchanger and the inlet to the cold medium outlet on the heat exchanger. In terms of flue gas treatment, the pretreatment mechanism includes a primary, secondary, and tertiary filter screen, forming a multi-stage filtration system. This system can progressively intercept dust and particulate matter of different sizes in the flue gas. Compared to traditional filtration equipment, it significantly improves the filtration effect on fine particulate matter and some harmful substances in the flue gas, effectively preventing impurities from entering the denitrification system and affecting the performance of the heat exchanger and catalyst layer, thus ensuring stable system operation.

Description

Technical Field

[0001] This utility model relates to the field of flue gas denitrification technology, and in particular to a low-temperature denitrification system based on self-exothermic heating. Background Technology

[0002] Flue gas denitrification, a key step in controlling industrial pollution, removes nitrogen oxides (NOx) from industrial flue gas through various means, including physical, chemical, and biological methods. x The process mainly involves NO and NO2 emissions. Its core objective is to significantly reduce nitrogen oxide emissions, thereby effectively preventing environmental pollution. In industrial production sectors, such as thermal power generation, steel smelting, waste incineration, and spent fuel processing in the nuclear industry, large amounts of NO-containing substances are generated during fuel combustion or chemical reactions. x The emission of nitrogen oxides into the atmosphere causes a series of serious environmental problems, such as acid rain, photochemical smog, and ozone layer depletion, while also posing a significant threat to the human respiratory system. Appropriate denitrification processes must be selected based on the characteristics of different flue gases. Common denitrification methods include selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), low-temperature plasma methods, and adsorption methods. Among these, SCR technology holds an important position in industrial applications due to its high denitrification efficiency and relatively stable operating performance.

[0003] In nuclear industry waste gas treatment scenarios, the waste gas temperature is typically low, making it difficult to reach the temperature conditions required for denitrification reactions. Therefore, it is necessary to reheat the waste gas to reach the denitrification reaction temperature. However, nuclear industry waste gas has unique characteristics. On the one hand, the NOx concentration in the flue gas is high, reaching up to 50,000 mg / Nm³. 3 On the other hand, the denitrification reaction itself is an exothermic reaction. Based on these characteristics, in order to fully utilize the heat released by the denitrification reaction and avoid the loss of heat carried in the flue gas after denitrification, the industry commonly adopts a technology of recovering heat from the flue gas through heat exchangers. The recovered heat is used to heat the exhaust gas before denitrification, raising its temperature to meet the requirements of the denitrification reaction. This method of heat recovery and utilization not only eliminates the need for continuous external heating, reducing energy consumption, but also aligns with the development concept of energy conservation and emission reduction.

[0004] However, in practical applications, the flue gas contains a large amount of dust and particulate matter. If these impurities enter the denitrification system directly without effective treatment, they will severely impact the critical equipment within the system. For heat exchangers, dust and particulate matter gradually deposit on the surface, forming a fouling layer. This increases the heat exchanger's thermal resistance and significantly reduces its heat exchange efficiency. Simultaneously, these impurities may clog the flow channels of the heat exchanger, affecting the normal flow of flue gas and further exacerbating the decline in heat exchange efficiency. For the catalyst layer, dust and particulate matter cover the catalyst surface, hindering the contact between the reactant gas and the catalyst's active sites, thereby reducing the catalyst's activity and shortening its lifespan.

[0005] To address the aforementioned issues, flue gas is typically pre-treated by filtration equipment, such as dust collectors, before entering the denitrification system. However, existing filtration equipment has several shortcomings in practical applications. Firstly, its filtration efficiency is poor, failing to effectively remove fine particulate matter and some harmful substances from the flue gas. This results in some impurities still entering subsequent denitrification equipment, affecting the normal operation of the system (e.g., impurities accumulating in heat exchangers reduce heat exchange efficiency and accumulating in catalyst layers affect reaction efficiency). Secondly, after long-term use, existing filtration equipment accumulates a large amount of dust and particulate matter internally. The cleaning process is extremely cumbersome, requiring significant manpower and time, and may even damage the equipment during cleaning, increasing maintenance costs and downtime, thus affecting the continuity and stability of production. Utility Model Content

[0006] The main objective of this invention is to provide a low-temperature denitrification system based on self-exothermic heating, which can effectively solve the problems in the background technology.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0008] A low-temperature denitrification system based on self-exothermic heating includes a denitrification tower. The tower's interior is equipped with an airflow distribution plate, and behind the distribution plate are five catalyst layers and six ammonia injection grids, arranged alternately. A heat exchanger and a supplementary heat exchanger are respectively installed at the tower's inlet and outlet. A first connecting pipe connects the heat exchanger and the inlet to the cold medium outlet of the heat exchanger. A pretreatment mechanism is connected to the cold medium inlet of the heat exchanger via a second connecting pipe. The pretreatment mechanism includes a treatment box, a rotating shaft, a driven bevel gear, and a cleaning plate. The treatment box contains a brush motor and a drive bevel gear. A primary, secondary, and tertiary filter screen are fixedly connected inside. A rotating shaft is movably connected to the bottom of a horizontal plate inside the treatment box via a rotating rod at the top. The rotating shaft passes through the primary, secondary, and tertiary filter screens. A cleaning plate corresponding to the primary, secondary, and tertiary filter screens is fixedly connected to the outer wall of the rotating shaft. A brush is fixedly connected to the top surface of the cleaning plate. The driven bevel gear is fixedly connected to the top of the rotating rod. The motor is fixedly connected to the outer wall of the treatment box, and the drive bevel gear is connected to the output end of the motor via a connecting shaft and meshes with the driven bevel gear.

[0009] Furthermore, a smoke inlet is fixedly installed on the bottom surface of the treatment box, and a smoke exhaust outlet is fixedly installed on the top surface of the treatment box. A second connecting pipe is fixedly installed between the smoke exhaust outlet and the cold medium inlet of the heat exchanger, and a flue gas pipe is fixedly installed at the bottom end of the smoke inlet.

[0010] Furthermore, three dust discharge ports are fixedly installed on the outer wall of the processing box in a vertical array, and the dust discharge ports are fixedly installed on the dust discharge pipe. The other end of the dust discharge pipe is fixedly installed on the input end of the dust removal fan, and a dust collection bag is fixedly installed on the output end of the dust removal fan.

[0011] Furthermore, a horizontal plate is fixedly installed on the upper part of the interior of the processing box, and a mounting hole is opened on the top surface of the horizontal plate, and a bearing is fixedly installed in the mounting hole.

[0012] Furthermore, the interior of the processing box is fixedly installed with a primary filter, a secondary filter, and a tertiary filter from bottom to top.

[0013] Furthermore, a rotating rod is fixedly installed at the top of the rotating shaft, and the rotating rod is fixedly installed together with the bearing. A driven bevel gear is fixedly installed at the top of the rotating rod. The rotating shaft passes through the third-stage filter, the second-stage filter, and the first-stage filter. Cleaning plates are also fixedly installed on the outer wall of the rotating shaft and below the third-stage filter, the second-stage filter, and the first-stage filter, respectively. A brush is fixedly installed on the top surface of the cleaning plate. The motor is fixedly installed on the outer wall of the treatment box, and a connecting shaft is fixedly installed on the output end of the motor. A driving bevel gear is fixedly installed at the other end of the connecting shaft, and the driving bevel gear and the driven bevel gear mesh together.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] In this invention, regarding flue gas treatment, the pretreatment mechanism comprises a multi-stage filtration system consisting of a primary filter, a secondary filter, and a tertiary filter. This system progressively intercepts dust and particulate matter of different particle sizes in the flue gas. Compared to traditional filtration equipment, this significantly improves the filtration efficiency for fine particulate matter and some harmful substances in the flue gas, effectively preventing impurities from entering the denitrification system and affecting the performance of the heat exchanger and catalyst layer, thus ensuring stable system operation. Regarding equipment maintenance, a motor-driven active bevel gear drives a driven bevel gear, which in turn rotates the shaft. Brushes on the cleaning plate clean each stage of the filter screens, and a dust removal fan extracts the cleaned dust and particulate matter, which is then collected by a dust collection bag. This prevents dust and particulate matter from accumulating on the filter screen surface, avoiding filter clogging, reducing downtime due to filter cleaning difficulties, lowering maintenance costs, facilitating equipment maintenance, reducing the risk of damage during cleaning, and improving production continuity and stability. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0017] Figure 2 This is a cross-sectional schematic diagram of the denitrification tower of this utility model;

[0018] Figure 3 This is a cross-sectional schematic diagram of the processing box of this utility model;

[0019] Figure 4 This is a schematic diagram of the overall structure of the pretreatment mechanism of this utility model.

[0020] In the diagram: 1. Denitrification tower; 2. Airflow distribution plate; 3. Catalyst layer; 4. Ammonia injection grid; 5. Heater; 6. Heat exchanger; 7. First connecting pipe; 8. Second connecting pipe; 9. Flue gas duct; 10. Pretreatment mechanism; 11. Treatment box; 12. Flue gas inlet; 13. Flue gas outlet; 14. Dust outlet; 15. Horizontal plate; 16. Mounting hole; 17. Bearing; 18. Dust discharge pipe; 19. Dust removal fan; 20. Dust collection bag; 21. Primary filter screen; 22. Secondary filter screen; 23. Tertiary filter screen; 24. Rotating shaft; 25. Rotating rod; 26. Driven bevel gear; 27. Cleaning plate; 28. Brush; 29. ​​Motor; 30. Connecting shaft; 31. Driving bevel gear. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0022] like Figure 1 - Figure 4 As shown, a low-temperature denitrification system based on self-exothermic heating includes a denitrification tower 1. The interior of the denitrification tower 1 is provided with an airflow distribution plate 2, and behind the airflow distribution plate 2, there are five layers of catalyst 3 and six layers of ammonia injection grids 4 respectively. The catalyst layers 3 and ammonia injection grids 4 are arranged alternately. The air inlet and outlet of the denitrification tower 1 are respectively provided with a heat exchanger 5 and a heat exchanger 6, and the heat exchanger 5 and the air inlet are connected to the cold medium outlet on the heat exchanger 6 by a first connecting pipe 7.

[0023] The existing principle of the low-temperature denitrification system based on self-exothermic heating is as follows:

[0024] The low-temperature flue gas first enters the supplementary heater 5, where it initially absorbs heat, raising its temperature. Then, the flue gas enters the denitrification tower 1 through its inlet. Upon entering the tower, the flue gas first encounters the airflow distribution plate 2, which evenly distributes the gas, allowing it to enter the subsequent denitrification reaction zone with a relatively uniform flow rate and distribution. Next, the flue gas enters the reaction zone formed by five catalyst layers 3 and six ammonia injection grids 4 arranged alternately. The six ammonia injection grids 4 evenly inject ammonia into the flue gas, ensuring thorough mixing. The mixed flue gas and ammonia then pass through the five catalyst layers 3 sequentially. In the catalyst layers 3, the ammonia reacts with nitrogen oxides (NOx) in the flue gas. xSelective catalytic reduction (SCR) occurs, reducing nitrogen oxides to nitrogen and water, thus achieving denitrification. The denitrification reaction is exothermic, releasing heat during the process and further increasing the flue gas temperature. The high-temperature denitrified flue gas exits from the outlet of denitrification tower 1 and enters heat exchanger 6. In heat exchanger 6, the high-temperature flue gas acts as the heat medium, exchanging heat with the cold medium (i.e., the pretreated low-temperature flue gas) entering heat exchanger 6 from pretreatment unit 10 via the second connecting pipe 8. The high-temperature flue gas releases heat and its temperature decreases, while the low-temperature flue gas absorbs heat and its temperature increases. After heat exchange, the low-temperature flue gas is discharged from the cold medium outlet of heat exchanger 6 and enters the supplementary heat exchanger 5 through the first connecting pipe 7. It mixes with the original low-temperature flue gas entering the supplementary heat exchanger 5, providing some heat to the original low-temperature flue gas and reducing the external heat input required by the supplementary heat exchanger 5. Only one heating supplement is needed before the flue gas is treated at the beginning. By making full use of the exothermic characteristics of the denitrification reaction, the heat of the flue gas after denitrification is recovered through heat exchanger 6 and used to heat the waste gas before denitrification, realizing heat recycling. There is no need for continuous external supplementary heating, which effectively reduces energy consumption, conforms to the concept of energy conservation and emission reduction, and reduces production costs.

[0025] A pretreatment mechanism 10 is connected to the cold medium inlet of heat exchanger 6 via a second connecting pipe 8. The pretreatment mechanism 10 includes a treatment box 11, a rotating shaft 24, a driven bevel gear 26, a cleaning plate 27, a brush 28, a motor 29, and a driving bevel gear 31. A primary filter 21, a secondary filter 22, and a tertiary filter 23 are fixedly connected inside the treatment box 11. The rotating shaft 24 is movably connected to the bottom of the horizontal plate 15 inside the treatment box 11 via a rotating rod 25 at the top. The rotating shaft 24 passes through a... The system includes a primary filter 21, a secondary filter 22, and a tertiary filter 23. A cleaning plate 27 corresponding to the primary filter 21, secondary filter 22, and tertiary filter 23 is fixedly connected to the outer wall of the rotating shaft 24. A brush 28 is fixedly connected to the top surface of the cleaning plate 27. A driven bevel gear 26 is fixedly connected to the top of the rotating rod 25. A motor 29 is fixedly connected to the outer wall of the treatment box 11. The driving bevel gear 31 is connected to the output end of the motor 29 through the connecting shaft 30 and meshes with the driven bevel gear 26.

[0026] like Figure 3 As shown, a flue gas inlet 12 is fixedly installed on the bottom surface of the treatment box 11, and a flue gas outlet 13 is fixedly installed on the top surface of the treatment box 11 to realize the entry and discharge of flue gas before treatment. A second connecting pipe 8 is fixedly installed between the flue gas outlet 13 and the cold medium inlet of the heat exchanger 6. The treated flue gas can be introduced into the heat exchanger 6 through the second connecting pipe 8. A flue gas pipe 9 is fixedly installed at the bottom end of the flue gas inlet 12. The flue gas pipe 9 can introduce the waste gas generated by the nuclear industry into the system for denitrification treatment.

[0027] like Figure 3As shown, three dust discharge ports 14 are fixedly installed on the outer wall of the processing box 11 in a vertical array, and the dust discharge ports 14 are fixedly installed on the dust discharge pipe 18. The other end of the dust discharge pipe 18 is fixedly installed on the input end of the dust removal fan 19, and a dust collection bag 20 is fixedly installed on the output end of the dust removal fan 19. After the dust removal fan 19 is started, it generates negative pressure and draws the dust and particulate matter generated during the cleaning of the processing box 11 into the dust discharge pipe 18 through the dust discharge ports 14, and collects them in the dust collection bag 20.

[0028] like Figure 3 As shown, a horizontal plate 15 is also fixedly installed on the upper part of the interior of the processing box 11, and a mounting hole 16 is provided on the top surface of the horizontal plate 15. A bearing 17 is fixedly installed in the mounting hole 16. The bearing 17 installed in the mounting hole 16 on the top surface of the horizontal plate 15 is used to cooperate with the rotating rod 25 to realize the rotation operation.

[0029] like Figure 4 As shown, the interior of the treatment box 11 is fixedly installed with a primary filter 21, a secondary filter 22 and a tertiary filter 23 from bottom to top. The primary filter 21, the secondary filter 22 and the tertiary filter 23 achieve multi-stage filtration of dust and particulate matter in the flue gas.

[0030] like Figure 4 As shown, a rotating rod 25 is fixedly installed at the top of the rotating shaft 24, and the rotating rod 25 is inserted and fixedly installed together with the bearing 17. A driven bevel gear 26 is fixedly installed at the top of the rotating rod 25. The rotating shaft 24 passes through the three-stage filter 23, the two-stage filter 22, and the first-stage filter 21. Cleaning plates 27 are also fixedly installed on the outer wall of the rotating shaft 24 and below the three-stage filter 23, the two-stage filter 22, and the first-stage filter 21. A brush 28 is fixedly installed on the top surface of the cleaning plate 27. The motor 29 is fixedly installed on the outer wall of the treatment box 11, and a connecting shaft is fixedly installed on the output end of the motor 29. 30. The other end of the connecting shaft 30 is fixedly installed with a drive bevel gear 31, and the drive bevel gear 31 and the driven bevel gear 26 mesh together. When the motor 29 is turned on, the output end drives the drive bevel gear 31 to rotate through the connecting shaft 30. Under the rotational meshing, the drive bevel gear 31 drives the driven bevel gear 26 to rotate. The driven bevel gear 26 will drive the rotating shaft 24 to rotate through the rotating rod 25. During the rotation, the rotating shaft 24 cleans the primary filter screen 21, the secondary filter screen 22 and the tertiary filter screen 23 through the brush 28 on the cleaning plate 27, so as to facilitate cleaning and maintenance.

[0031] The operating principle of the pretreatment unit 10, in conjunction with the low-temperature denitrification system based on self-exothermic heating, is as follows:

[0032] When the pretreatment unit 10 is working, the waste gas generated by the nuclear industry enters the treatment box 11 through the flue gas duct 9 from the inlet 12. The flue gas entering the treatment box 11 passes through the primary filter 21, the secondary filter 22, and the tertiary filter 23 in sequence. These three filter layers constitute a multi-stage filtration system. The primary filter 21 first intercepts larger dust and particulate matter in the flue gas, the secondary filter 22 further intercepts medium-sized impurities, and the tertiary filter 23 intercepts small-sized particulate matter and some harmful substances, achieving multi-stage filtration of the flue gas, effectively removing impurities from the flue gas, and preventing impurities from entering the subsequent denitrification system and affecting equipment performance. During the filtration process, impurities will adhere to the filter surface. During long-term use, in order to prevent filter clogging and ensure the filtration effect of the pretreatment unit 10, the motor 29 is turned on to drive the output end to rotate the connecting shaft 30. The connecting shaft 30 drives the active bevel gear 31 to rotate. Since the active bevel gear 31 and the driven bevel gear 26 mesh with each other, the rotation of the active bevel gear 31 will drive the driven bevel gear 26. The driven bevel gear 26 rotates, causing the rotating rod 25 to rotate within the bearing 17 installed in the mounting hole 16 on the top surface of the horizontal plate 15. The rotating rod 25 drives the rotating shaft 24 to rotate, which in turn drives the cleaning plate 27 fixedly connected to its outer wall to rotate. The brush 28 on the top surface of the cleaning plate 27 rotates accordingly, and the brush 28 cleans the bottom surfaces of the primary filter screen 21, the secondary filter screen 22, and the tertiary filter screen 23, sweeping off the impurities attached to the filter screen surfaces. At the same time, the dust removal fan 19 is turned on. The operation of the 19 unit generates negative pressure, which draws the dust and particulate matter swept off the treatment box 11 by the brush 28 into the dust discharge pipe 18 and the dust discharge port 14, and finally into the dust collection bag 20 for collection, thus cleaning the impurities. The pre-treated low-temperature flue gas is discharged from the exhaust port 13 on the top surface of the treatment box 11, and enters the cold medium inlet of the heat exchanger 6 through the second connecting pipe 8 to participate in the subsequent heat exchange and denitrification process, thereby improving the flue gas treatment effect and maintaining the equipment.

[0033] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A low-temperature denitrification system based on self-exothermic heating, comprising a denitrification tower (1), wherein the interior of the denitrification tower (1) is provided with an airflow distribution plate (2), and five layers of catalyst layers (3) and six layers of ammonia injection grids (4) are respectively provided behind the airflow distribution plate (2), wherein the catalyst layers (3) and ammonia injection grids (4) are arranged alternately between each other, wherein a heat exchanger (5) and a heat inlet and an outlet of the denitrification tower (1) are respectively provided, and a first connecting pipe (7) is connected between the heat exchanger (5) and the air inlet and the cold medium outlet on the heat exchanger (6), characterized in that: The heat exchanger (6) is connected to a pretreatment mechanism (10) via a second connecting pipe (8) at the cold medium inlet. The pretreatment mechanism (10) includes a treatment box (11), a rotating shaft (24), a driven bevel gear (26), a cleaning plate (27), a brush (28), a motor (29), and a driving bevel gear (31). The treatment box (11) is fixedly connected to a primary filter (21), a secondary filter (22), and a tertiary filter (23). The rotating shaft (24) is movably connected to the bottom of the transverse plate (15) inside the treatment box (11) via a rotating rod (25) at the top. The rotating shaft (24) passes through... The filter passes through a primary filter (21), a secondary filter (22), and a tertiary filter (23). A cleaning plate (27) corresponding to the primary filter (21), secondary filter (22), and tertiary filter (23) is fixedly connected to the outer wall of the rotating shaft (24). A brush (28) is fixedly connected to the top surface of the cleaning plate (27). The driven bevel gear (26) is fixedly connected to the top of the rotating rod (25). The motor (29) is fixedly connected to the outer wall of the processing box (11). The driving bevel gear (31) is connected to the output end of the motor (29) through the connecting shaft (30) and meshes with the driven bevel gear (26).

2. The low-temperature denitrification system based on self-exothermic heating according to claim 1, characterized in that: The bottom surface of the processing box (11) is fixedly equipped with a smoke inlet (12), and the top surface of the processing box (11) is fixedly equipped with a smoke outlet (13). A second connecting pipe (8) is fixedly installed between the smoke outlet (13) and the cold medium inlet of the heat exchanger (6). A flue gas pipe (9) is fixedly installed at the bottom end of the smoke inlet (12).

3. The low-temperature denitrification system based on self-exothermic heating according to claim 2, characterized in that: Three dust discharge ports (14) are fixedly installed on the outer wall of the processing box (11) in a vertical array, and the dust discharge ports (14) are fixedly installed on the dust discharge pipe (18). The other end of the dust discharge pipe (18) is fixedly installed on the input end of the dust removal fan (19), and a dust collection bag (20) is fixedly installed on the output end of the dust removal fan (19).

4. The low-temperature denitrification system based on self-exothermic heating according to claim 3, characterized in that: A horizontal plate (15) is fixedly installed on the upper part of the inside of the processing box (11), and a mounting hole (16) is opened on the top surface of the horizontal plate (15). A bearing (17) is fixedly installed in the mounting hole (16).

5. A low-temperature denitrification system based on self-exothermic heating according to claim 4, characterized in that: The processing box (11) is equipped with a primary filter (21), a secondary filter (22) and a tertiary filter (23) installed from bottom to top inside.

6. A low-temperature denitrification system based on self-exothermic heating according to claim 5, characterized in that: A rotating rod (25) is fixedly installed at the top of the rotating shaft (24), and the rotating rod (25) is inserted and fixedly installed together with the bearing (17). A driven bevel gear (26) is fixedly installed at the top of the rotating rod (25). The rotating shaft (24) passes through the third-stage filter (23), the second-stage filter (22), and the first-stage filter (21). A cleaning plate (27) is also fixedly installed on the outer wall of the rotating shaft (24) and below the third-stage filter (23), the second-stage filter (22), and the first-stage filter (21). A brush (28) is fixedly installed on the top surface of the cleaning plate (27). The motor (29) is fixedly installed on the outer wall of the treatment box (11), and a connecting shaft (30) is fixedly installed on the output end of the motor (29). A driving bevel gear (31) is fixedly installed at the other end of the connecting shaft (30), and the driving bevel gear (31) and the driven bevel gear (26) mesh together.

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