A double-tower purification process for nitrous oxide

Abstract

The invention discloses a double-tower purification process for nitrous oxide, and relates to the technical field of nitrous oxide purification. The process comprises the following steps: S1: raw material preparation, wherein the nitrous oxide raw material is passed through a filtering device to filter out solid impurities, so as to obtain a raw material liquid; S2: low-boiling separation, wherein the raw material liquid is transported from a feed pipe to the inside of a first distillation tower through a compressor, and impurities in the raw material liquid with a boiling point lower than that of nitrous oxide are separated to obtain a primary separation stock liquid; S3: high-boiling separation, wherein the primary separation stock liquid is transported from the first distillation tower to the inside of a second distillation tower, and impurities in the primary separation stock liquid with a boiling point higher than that of nitrous oxide are separated to obtain a nitrous oxide liquid. The invention replaces an adsorption tower with a distillation tower, thereby not only reducing the replacement and maintenance costs of an adsorbent, but also greatly reducing the equipment complexity of a nitrous oxide purification system, and also making both the nitrous oxide raw material and the final product liquid, which is convenient for storage and transportation.

Description

Technical Field

[0001] The invention relates to the technical field of nitrous oxide purification, and in particular to a double-tower nitrous oxide purification process. Background Art

[0002] In the semiconductor production process, high-purity nitrous oxide is a key reaction gas in the chemical vapor deposition process, and its purity is usually above 99.999%. For high-precision electronic equipment such as extreme ultraviolet lithography equipment, high-resolution liquid crystal displays and organic light-emitting diode displays, high-purity nitrous oxide is an ideal cleaning gas.

[0003] However, nitrous oxide obtained from industrial waste gas or other sources often contains a variety of impurities, such as water, carbon dioxide, oxygen, nitrogen, methane, carbon monoxide, etc. These impurities seriously affect the purity and performance of nitrous oxide.

[0004] The existing purification method is that the compressed gas enters the first adsorption tower, and the tower is filled with a specific adsorbent combination, which is filled in the tower according to a specific ratio and layered structure. The gas is fully in contact with the adsorbent in the first adsorption tower, and the carbon dioxide and water therein are adsorbed by the adsorbent to obtain preliminarily purified nitrous oxide gas. When the adsorbent reaches the saturated adsorption capacity, the adsorbent is regenerated by decompression regeneration or displacement regeneration, and the regenerated adsorbent can continue to be recycled; the preliminarily purified nitrous oxide gas from the first adsorption tower enters the second distillation tower, and the second distillation tower adopts a packed tower. By controlling the tower top temperature, tower bottom temperature, reflux ratio, etc. of the distillation tower, the nitrous oxide is further purified and enriched at the top of the tower to obtain nitrous oxide with higher purity.

[0005] The Chinese patent with application number CN202211714098.8 discloses a 6N grade nitrous oxide distillation device and distillation method. The invention is connected in sequence by a purifier, a liquefier and a distillation tower; a liquid inlet is provided on the side of the distillation tower, a liquid outlet is provided at the bottom, and an emptying pipe with an emptying valve is provided on the top; the liquid inlet and the liquid outlet of the distillation tower are respectively connected to the heat exchanger through a pipe; impurities such as H2O, CO2, N2, H2, NO, CO, O2, Ar in the crude nitrous oxide are removed, so that the content of the above components in the nitrous oxide product obtained by distillation is maintained at 10ppb or less. However, the invention is not only complex in equipment, but also requires a compressor to compress the gas to a very high pressure for adsorption, which generates very large energy consumption, and the molecular sieve has a certain life span, and the molecular sieve needs to be replaced regularly, and there is a problem of extremely high maintenance costs in the later stage.

[0006] A Chinese patent with application number CN202210925070.2 discloses a plate distillation tower. The invention adjusts the number of sieve holes on the tower plate to increase the top pressure of a single sieve hole on the liquid and reduce leakage; and prevents flooding by adjusting the distance between the tower plates. However, the equipment is very complex, making the installation of the distillation tower more difficult, and it cannot be adaptively adjusted according to the leakage or flooding of the tower plate. At the same time, reducing the sieve holes will also cause part of the raw liquid to not fully transfer mass with the gas, resulting in low separation efficiency of the raw liquid.

[0007] To this end, the present invention proposes a double-tower purification process for nitrous oxide to solve the above problems. Summary of the invention

[0008] The object of the present invention is to provide a double-tower purification process for nitrous oxide, so as to solve the technical problems of complex equipment and high energy consumption in the purification system of nitrous oxide proposed in the above background technology.

[0009] To achieve the above object, the present invention provides the following technical solution: a double-tower purification process for nitrous oxide, comprising the following steps:

[0010] S1: raw material preparation, passing the nitrous oxide raw material into a filtering device to filter out solid impurities to obtain a raw material liquid;

[0011] S2: low boiling separation, the raw material liquid is transported from the feed pipe to the inside of the first distillation tower by a compressor, and impurities with a boiling point lower than that of nitrous oxide in the raw material liquid are separated to obtain a primary separation raw liquid;

[0012] S3: high boiling separation, the primary separation liquid is transported from the first distillation tower to the second distillation tower, the temperature in the first distillation tower is higher than the temperature in the second distillation tower, during the primary separation liquid vaporization and ascent, the adjustment components arranged on the multiple trays adjust the cross-sectional area of ​​the sieve holes on the trays according to the leakage or flooding phenomenon, and the impurities with a boiling point higher than that of nitrous oxide in the primary separation liquid are separated to obtain nitrous oxide liquid;

[0013] The adjustment component includes a fixing part fixedly connected to the bottom of the tower plate, a movable part sliding up and down is arranged between the fixing part and the tower plate, and a plurality of adjustment parts matching the sieve holes are fixedly connected to the movable part. When the movable part moves up and down, the cross-sectional area of ​​the sieve holes can change accordingly.

[0014] Preferably, the first distillation tower is a packed distillation tower, the second distillation tower is a plate distillation tower, a feed pipe is provided in the middle of the first distillation tower, and a conveying member is provided between the second distillation tower and the first distillation tower.

[0015] Preferably, the second distillation tower includes a tower body, and the plurality of tower plates are respectively fixedly connected to the tower body and arranged up and down, a step groove is provided on one side of the tower plate, an overflow weir and a downcomer are provided on the side of the tower plate away from the step groove, and the regulating assembly is located between the tower plate and the downcomer.

[0016] Preferably, the fixing member includes a fixing plate fixedly connected to the tower plate and the downcomer, the fixing plate is provided with a plurality of first through holes matching the sieve holes, the movable member includes a movable plate located between the fixing plate and the tower plate, a first elastic member is provided between the movable plate and the fixed plate, a plurality of second through holes are provided on the movable plate, and the second through holes are staggered with the sieve holes.

[0017] Preferably, the adjusting member comprises a fixing column coaxially arranged with the sieve hole, and an inverted conical block is fixedly connected to a side of the fixing column away from the movable plate.

[0018] Preferably, a scraper is provided on the fixed column, and the scraper can clean the upper and lower sides of the sieve hole when the scraper moves up and down following the adjusting member.

[0019] Preferably, the scraper comprises an annular plate coaxially arranged with the sieve hole, and the fixed column is provided with a connecting frame fixedly connected with the annular plate.

[0020] Preferably, a defoaming member is disposed below each of the first through holes, and the defoaming member comprises a conical defoaming mesh.

[0021] Preferably, an adjustment groove is provided in the stepped groove, a sensing plate is slidably connected in the adjustment groove, a second elastic member is arranged between the sensing plate and the adjustment groove, a plurality of slots are respectively provided on both sides of the bottom of the tower plate, a card block and a positioning block matching the slots are respectively fixed on both sides of the fixed plate and the movable plate, a flow channel connected to the adjustment groove is provided on the card block, a plurality of the first elastic members are multi-stage telescopic cylinders and are respectively fixed on the card blocks, the bottom of the multi-stage telescopic cylinders is connected to the flow channel, and a connecting pipe is arranged between the two multi-stage telescopic cylinders along the length direction of the tower plate.

[0022] Preferably, a sealing ring is provided on the outer wall of the induction plate.

[0023] The beneficial effects of the present invention are:

[0024] 1. The present invention replaces the adsorption tower with a distillation tower, which not only reduces the replacement and maintenance costs of the adsorbent, but also greatly reduces the equipment complexity of the nitrous oxide purification system, and also makes the nitrous oxide raw material and the final product both liquid, which is convenient for storage and transportation.

[0025] 2. The present invention is provided with adjusting components, fixing parts, movable parts and adjusting parts. When liquid leakage occurs in the distillation tower, a large amount of liquid leaks onto the movable plate. The movable plate moves downward under the action of liquid pressure, causing the conical block to move toward the sieve hole. At this time, the cross-sectional area of ​​the sieve hole is reduced, so that the flow rate of the gas passing through the sieve hole is increased, thereby increasing the supporting pressure of the gas on the liquid, thereby improving the leakage problem; similarly, when liquid flooding occurs in the distillation tower, the movable plate moves upward under the action of gas pressure, and the conical block moves away from the sieve hole. The cross-sectional area of ​​the sieve hole becomes larger, thereby reducing the gas flow rate in the sieve hole, thereby improving the liquid flooding problem. This method greatly reduces the probability of liquid leakage and liquid flooding, and does not require excessive participation of workers. On the basis of ensuring the purification effect of nitrous oxide, the labor intensity of workers is greatly reduced, and the purification efficiency of nitrous oxide is improved.

[0026] 3. The present invention is provided with a scraper, a movable plate and a foam removal screen. The scraper can clean the edge of the sieve hole following the up and down movement of the movable plate to prevent carbon dioxide from forming dry ice or water crystallization and clogging the sieve hole; and with the setting of the foam removal screen, the gas passing through the first through hole can be separated into gas and liquid, thereby improving the subsequent gas-liquid mass transfer efficiency and also improving the problem of liquid foam entrainment.

[0027] 4. The present invention is provided with an adjustment groove, a sensing plate, a second elastic member and a multi-stage telescopic cylinder. The sensing plate moves according to the weight of the liquid in the downcomer and the stepped groove. When leakage occurs, the weight on the sensing plate decreases and rises, causing the movable plate to descend. When liquid overflow occurs, the weight on the sensing plate increases and descends, causing the movable plate to rise. In this way, the up and down movement of the movable plate can be made more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a double-tower purification process flow chart of nitrous oxide.

[0029] Figure 2 It is a schematic diagram of the structure of the first distillation tower and the second distillation tower of the present invention.

[0030] Figure 3 It is a schematic diagram of the cross-sectional structure of the second distillation tower of the present invention.

[0031] Figure 4 It is a schematic diagram of the structure of the tower tray and the adjustment assembly of the present invention.

[0032] Figure 5 It is a side view schematic diagram of the tower tray and the adjustment assembly of the present invention.

[0033] Figure 6 It is a schematic top view of the tower tray of the present invention.

[0034] Figure 7for Figure 6 Schematic diagram of the cross section at AA in the middle.

[0035] Figure 8 for Figure 6 Schematic diagram of the cross section at BB in the middle.

[0036] Fig. 9 for Figure 7 A schematic diagram of the enlarged structure at point A in the middle.

[0037] Fig.10 for Figure 8 A magnified schematic diagram of the structure at point B in the middle.

[0038] Fig.11 It is a schematic diagram of the structure of the adjusting member and the scraping member.

[0039] The accompanying drawings are marked as follows:

[0040] 1. first distillation tower; 11. feed pipe; 12. first reboiler; 13. first condenser;

[0041] 2. second distillation tower; 21. tower body; 22. second reboiler; 23. second condenser;

[0042] 3. Tower tray; 31. Sieve hole; 32. Step groove; 33. Card slot;

[0043] 4. Adjustment assembly; 41. Fixing member; 411. Fixing plate; 412. First through hole; 413. Block; 42. Movable member; 421. Movable plate; 422. Second through hole; 423. Positioning block; 43. Adjustment member; 431. Fixing column; 432. Conical block; 44. First elastic member; 45. Scraping member; 451. Annular plate; 452. Connecting frame; 46. Foam removal screen;

[0044] 5. Overflow weir;

[0045] 6. Downcomer;

[0046] 7. Adjusting groove; 71. Induction plate; 72. Second elastic member; 73. Flow channel; 74. Connecting pipe; 75. Sealing ring. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0048] Example 1

[0049] In the actual production process, the existing purification method requires a compressor to compress the gas to a very high pressure for adsorption, which results in very high energy consumption. In addition, the adsorbent has a certain lifespan and needs to be replaced regularly, resulting in extremely high maintenance costs. This embodiment is specially invented to solve the above problems.

[0050] See also Figures 1 to 11 As shown, a double-tower purification process for nitrous oxide according to an embodiment of the present invention comprises the following steps:

[0051] S1: raw material preparation, the raw material containing nitrous oxide is passed into a filtering device for filtering, solid impurities in the raw material are filtered out, and a raw material liquid is obtained;

[0052] S2: low boiling separation, the pressurized raw material liquid is transported from the feed pipe 11 to the inside of the first distillation tower 1 by a compressor, the temperature of the first distillation tower 1 is about -76°C, and the nitrous oxide is separated according to the difference in boiling points between the nitrous oxide and the impurities therein, such as oxygen, nitrogen, etc., and the raw material liquid is vaporized and raised by a first reboiler 12 arranged in the kettle of the first distillation tower 1, and the first condenser 13 arranged in the top of the first distillation tower 1 is provided with low-temperature nitrogen, so that the top gas is liquefied and used as reflux liquid, and the low boiling point impurities are discharged from the top of the tower together with the exhaust gas, and the first distillation tower 1 is used to separate the impurities in the raw material liquid that are lower than the boiling point of nitrous oxide to obtain a primary separation stock liquid;

[0053] S3: high boiling separation, the primary separation stock solution is pumped from the bottom of the first distillation tower 1 to the middle of the second distillation tower 2, the temperature in the first distillation tower 1 is higher than the temperature in the second distillation tower 2, the temperature in the second distillation tower 2 is about -82°C, the primary separation stock solution is vaporized and ascended by the second reboiler 22 arranged in the bottom of the second distillation tower 2, during the ascending process, the diameter of the sieve hole 31 on the tower plate 3 is adjusted according to the leakage or flooding of the tower plate 3 by the adjusting component 4 arranged on the tower plate 3, the gas at the top of the tower is liquefied by the second condenser 23 arranged at the top of the second distillation tower 2, part of which is used as reflux liquid, and the rest is drawn out from the top of the second distillation tower 2 as product liquid, and the impurities (water) with a boiling point higher than nitrous oxide in the primary separation stock solution are separated by the second distillation tower 2 to obtain nitrous oxide liquid.

[0054] The first distillation tower 1 is a packed distillation tower, the second distillation tower 2 is a plate distillation tower, a feed pipe 11 is arranged in the middle of the first distillation tower 1 , and a conveying member is arranged between the second distillation tower 2 and the first distillation tower 1 .

[0055] The conveying member includes a conveying pipe, a pump, a thyristor and a valve. One end of the conveying pipe is connected to the bottom of the first distillation tower 1 , and the other end is connected to the middle of the second distillation tower 2 .

[0056] By replacing the adsorption tower with a distillation tower, not only the replacement and maintenance costs of the adsorbent are reduced, the equipment complexity of the nitrous oxide purification system is greatly reduced, but also the nitrous oxide raw material and the final product are both liquid, which is convenient for storage and transportation.

[0057] Example 2

[0058] During the use of the distillation tower, leakage, liquid foam entrainment and flooding are basically unavoidable. These phenomena not only reduce the mass transfer efficiency between gas and liquid, thereby affecting the purification effect of nitrous oxide, but also require workers to spend a lot of time adjusting the parameters of the reboiler or feed system, and even need to overhaul the tray 3 inside it, which is very time-consuming and labor-intensive. In view of the above problems, further improvements are made on the basis of the above embodiments.

[0059] See also Figure 4 and Figure 5 As shown, the adjustment component 4 includes a fixing part 41 fixedly connected to the bottom of the tower plate 3, a movable part 42 that slides up and down is arranged between the fixing part 41 and the tower plate 3, and a plurality of adjustment parts 43 matching the sieve holes 31 are fixedly connected to the movable part 42. When the movable part 42 moves up and down, the cross-sectional area of ​​the sieve holes 31 increases or decreases.

[0060] See also Figure 3 , Figure 4 and Figure 5 As shown, the second distillation tower 2 includes a tower body 21, and a plurality of tower plates 3 are respectively fixedly connected to the tower body 21 and arranged up and down. A step groove 32 is arranged on one side of the tower plate 3, and an overflow weir 5 and a downcomer 6 are arranged on the side of the tower plate 3 away from the step groove 32. When the raw liquid enters the step groove 32 through the downcomer 6, it will enter the gas-liquid mass transfer area of ​​the sieve hole 31 only after the raw liquid overflows the step groove 32. Compared with the conventional tower plate 3, this method makes the liquid distribution on the tower plate 3 more uniform, and the regulating component 4 is located between the tower plate 3 and the downcomer 6.

[0061] See also Figures 7 to 10 As shown, further supplementing the structure of the fixed member 41 and the movable member 42 is that the fixed member 41 includes a fixed plate 411 fixedly connected to the tower tray 3 and the downcomer 6, and a plurality of first through holes 412 matching the sieve holes 31 are opened on the fixed plate 411, and the movable member 42 includes a movable plate 421 located between the fixed plate 411 and the tower tray 3, a first elastic member 44 is arranged between the movable plate 421 and the fixed plate 411, and a plurality of second through holes 422 are arranged on the movable plate 421, and the second through holes 422 are staggered with the sieve holes 31. In this embodiment, the diameters of the first through holes 412 and the second through holes 422 are consistent with the diameter of the sieve holes 31.

[0062] The adjusting member 43 includes a fixing column 431 coaxially arranged with the sieve hole 31 , and an inverted conical block 432 is fixedly connected to a side of the fixing column 431 away from the movable plate 421 .

[0063] During use, after the worker fixes the tray 3 with the adjustment assembly 4 installed inside the distillation tower, the gas generated by the vaporization of the raw liquid rises from the bottom to the top of the distillation tower. During the rising process of the gas, if flooding occurs between a certain section of the trays 3, the gas pressure between the two trays 3 where flooding occurs rises, and the gas passes through the first through hole 412 and directly acts on the bottom surface of the movable plate 421, causing the movable plate 421 to move upward under the action of the gas pressure. At this time, the conical block 432 moves upward away from the sieve hole 31, and the cross-sectional area of ​​the sieve hole 31 increases, so that the gas flow rate through the sieve hole 31 becomes larger, which reduces the gas flow rate to a certain extent, and then reduces the drag of the gas on the liquid. Under the action of gravity, the liquid can more easily overcome the gas obstacle and smoothly flow through the downcomer 6 to the next tray 3, thereby reducing the accumulation of liquid on the tray 3 and improving the flooding phenomenon.

[0064] At the same time, if the gas phase load in the distillation tower is low, the rising speed of the gas is too small, and sufficient pressure cannot be provided to support the liquid on the tower plate 3, the liquid will directly leak from the sieve hole 31, resulting in leakage. When leakage occurs, a large amount of liquid gathers on the movable plate 421, and the movable plate 421 moves downward under the action of liquid pressure, so that the conical block 432 approaches the sieve hole 31. At this time, the cross-sectional area of ​​the sieve hole 31 is reduced, thereby increasing the flow rate of the gas through the sieve hole 31, thereby increasing the supporting pressure of the gas on the liquid, and solving the leakage problem of the tower plate 3.

[0065] By adjusting the components 4, the fixing parts 41, the movable parts 42 and the adjusting parts 43, when liquid leakage occurs in the distillation tower, a large amount of liquid leaks onto the movable plate 421, and the movable plate 421 moves downward under the action of the liquid pressure, so that the conical block 432 moves toward the direction of the sieve hole 31. At this time, the cross-sectional area of ​​the sieve hole 31 is reduced, so that the flow rate of the gas passing through the sieve hole 31 increases, thereby increasing the supporting pressure of the gas on the liquid, and improving the leakage problem; similarly, when liquid flooding occurs in the distillation tower, the movable plate 421 moves upward under the action of the gas pressure, and the conical block 432 moves away from the sieve hole 31. The cross-sectional area of ​​the sieve hole 31 becomes larger, thereby reducing the gas flow rate in the sieve hole 31, and improving the liquid flooding problem. This method greatly reduces the probability of liquid leakage and liquid flooding, and does not require too much participation of workers. On the basis of ensuring the purification effect of nitrous oxide, the labor intensity of workers is greatly reduced, and the purification efficiency of nitrous oxide is improved.

[0066] Example 3

[0067] After the nitrous oxide raw liquid is purified and separated in the first distillation tower 1, the raw material impurities entering the second distillation tower 2 are heavy component impurities, such as carbon dioxide and water. Since the internal temperature of the second distillation tower 2 is about -82°C, carbon dioxide and water are easy to form crystals at the edge of the sieve holes 31 when passing through the sieve holes 31 of the tray 3. In severe cases, the sieve holes 31 may even be blocked, which leads to uneven gas-liquid distribution in the distillation tower, increased mist entrainment, and increased probability of flooding. In view of the above problems, further improvements are made on the basis of the above embodiments.

[0068] See also Fig. 9 As shown, a scraper 45 is provided on the fixed column 431 , and the scraper 45 can clean the upper and lower sides of the sieve hole 31 when following the upward and downward movement of the adjusting member 43 .

[0069] See also Fig.11 As shown, the scraper 45 includes an annular plate 451 coaxially arranged with the sieve hole 31 , and a connecting frame 452 fixedly connected to the annular plate 451 is arranged on the fixing column 431 .

[0070] See also Fig. 9 As shown, a defoaming member is disposed below each of the plurality of first through holes 412 , and the defoaming member includes a conical defoaming mesh 46 .

[0071] When in use, every time the gas passes through the first through hole 412, the defoaming mesh 46 will filter the liquid carried in the gas. The gas after filtering the liquid has a better mass transfer effect with the original liquid. When mist entrainment occurs, the defoaming mesh 46 has a better defoaming effect on the gas. In addition, since the defoaming mesh 46 is set in a cone shape, it is convenient for the filtered liquid to drip.

[0072] At the same time, whenever the adjusting member 43 moves up and down following the movable plate 421 , the scraping member 45 will also move up and down in the sieve hole 31 and clean the edge of the sieve hole 31 to prevent the sieve hole 31 from being blocked.

[0073] To sum up, through the settings of the scraper 45, the movable plate 421 and the foam removal screen 46, the scraper 45 can follow the up and down movement of the movable plate 421 to clean the edge of the sieve hole 31 to prevent carbon dioxide from forming dry ice or water crystallization and clogging the sieve hole 31; and under the setting of the foam removal screen 46, the gas passing through the first through hole 412 can be separated into gas and liquid, thereby improving the subsequent gas-liquid mass transfer efficiency and also improving the problem of liquid foam entrainment.

[0074] Example 4

[0075] In order to make the movable plate 421 have a more stable movement capability after leakage or flooding occurs, further improvements are made on the basis of the above embodiment.

[0076] See also Figure 8 and Fig.10 As shown, an adjusting groove 7 is provided in the stepped groove 32, and a sensing plate 71 is slidably connected in the adjusting groove 7. A sealing ring 75 is provided on the outer wall of the sensing plate 71, and a second elastic member 72 is provided between the sensing plate 71 and the adjusting groove 7. A plurality of card slots 33 are provided on both sides of the bottom of the tower plate 3, and a card block 413 and a positioning block 423 matching the card slot 33 are fixed on both sides of the fixed plate 411 and the movable plate 421, respectively. A flow channel 73 connected to the adjusting groove 7 is provided on the card block 413, and a plurality of first elastic members 44 are multi-stage telescopic cylinders and are respectively fixed on the card block 413. The bottom of the multi-stage telescopic cylinder is connected to the flow channel 73, and a connecting pipe 74 is provided between two multi-stage telescopic cylinders along the length direction of the tower plate 3. Hydraulic oil or compressed gas is provided in the adjusting groove 7, the flow channel 73, the multi-stage telescopic cylinder and the connecting pipe 74.

[0077] During use, when leakage occurs in the distillation tower, a large amount of liquid will directly leak from the sieve hole 31 to the tower plate 3 of the next layer, and the liquid accumulated in the downcomer 6 and the next layer of stepped groove 32 will be reduced. The induction plate 71 will move upward under the action of the second elastic member 72, and the volume in the adjustment groove 7 will increase, causing the multi-stage telescopic cylinder to shrink. At this time, the movable plate 421 moves downward following the multi-stage telescopic cylinder.

[0078] When liquid flooding occurs between the two trays 3, the amount of liquid accumulated in the downcomer 6 and the stepped groove 32 increases, causing the induction plate 71 to break through the elastic force of the second elastic member 72 and be compressed downward. At this time, the hydraulic oil or compressed gas in the regulating groove 7 enters the multi-stage telescopic cylinder, causing the multi-stage telescopic cylinder to expand and move the movable plate 421 upward.

[0079] By adjusting the groove 7, the sensing plate 71, the second elastic member 72 and the multi-stage telescopic cylinder, the sensing plate 71 moves according to the weight of the liquid in the downcomer 6 and the stepped groove 32. When leakage occurs, the weight on the sensing plate 71 decreases and rises, causing the movable plate 421 to descend. When liquid overflow occurs, the weight on the sensing plate 71 increases and descends, causing the movable plate 421 to rise. In this way, the up and down movement of the movable plate 421 can be made more stable.

[0080] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A double-tower purification process for nitrous oxide, characterized in that: The following steps are involved: S1: raw material preparation, passing the nitrous oxide raw material into a filtering device to filter out solid impurities to obtain a raw material liquid; S2: low boiling separation, the raw liquid is transported from the feed pipe (11) to the inside of the first distillation tower (1) by a compressor, and impurities with a boiling point lower than that of nitrous oxide in the raw liquid are separated to obtain a primary separation raw liquid; S3: high boiling separation, the primary separation raw liquid is transported from the first distillation tower (1) to the second distillation tower (2), the temperature in the first distillation tower (1) is higher than the temperature in the second distillation tower (2), during the process of the primary separation raw liquid vaporizing and ascending, the cross-sectional area of ​​the sieve holes (31) on the tower plates (3) is adjusted according to the leakage or flooding phenomenon by means of the regulating components (4) arranged on the plurality of tower plates (3), so as to separate the impurities with a boiling point higher than that of nitrous oxide in the primary separation raw liquid, thereby obtaining nitrous oxide liquid; The adjustment assembly (4) comprises a fixing member (41) fixedly connected to the bottom of the tower plate (3); a movable member (42) sliding up and down is arranged between the fixing member (41) and the tower plate (3); a plurality of adjustment members (43) matching the sieve holes (31) are fixedly connected to the movable member (42); when the movable member (42) moves up and down, the cross-sectional area of ​​the sieve holes (31) can change accordingly; The fixed member (41) comprises a fixed plate (411) fixedly connected to the tower tray (3) and the downcomer (6); the fixed plate (411) is provided with a plurality of first through holes (412) matching the sieve holes (31); the movable member (42) comprises a movable plate (421) located between the fixed plate (411) and the tower tray (3); a first elastic member (44) is provided between the movable plate (421) and the fixed plate (411); the movable plate (421) is provided with a plurality of second through holes (422), and the second through holes (422) are arranged in a staggered manner with the sieve holes (31); The adjusting member (43) comprises a fixing column (431) coaxially arranged with the sieve hole (31), and an inverted conical block (432) is fixedly connected to a side of the fixing column (431) away from the movable plate (421).

2. A nitrous oxide double-tower purification process according to claim 1, characterized in that: The first distillation tower (1) is a packed distillation tower, the second distillation tower (2) is a plate distillation tower, a feed pipe (11) is arranged in the middle of the first distillation tower (1), and a conveying member is arranged between the second distillation tower (2) and the first distillation tower (1).

3. A nitrous oxide double-tower purification process according to claim 2, characterized in that: The second distillation tower (2) comprises a tower body (21), a plurality of tower trays (3) are respectively fixedly connected to the tower body (21) and arranged in an up-and-down arrangement, a stepped groove (32) is provided on one side of the tower tray (3), an overflow weir (5) and a downcomer (6) are provided on a side of the tower tray (3) away from the stepped groove (32), and the regulating assembly (4) is located between the tower tray (3) and the downcomer (6).

4. A double-tower nitrous oxide purification process according to claim 3, characterized in that: The fixed column (431) is provided with a scraper (45), and the scraper (45) can clean the upper and lower sides of the sieve hole (31) as it moves up and down following the adjusting member (43).

5. A double-tower purification process for nitrous oxide according to claim 4, characterized in that: The scraper (45) comprises an annular plate (451) coaxially arranged with the sieve hole (31), and the fixed column (431) is provided with a connecting frame (452) fixedly connected to the annular plate (451).

6. A double-tower purification process for nitrous oxide according to claim 5, characterized in that: A defoaming piece is provided below each of the plurality of first through holes (412), and the defoaming piece comprises a conical defoaming mesh (46).

7. A double-tower purification process for nitrous oxide according to claim 6, characterized in that: An adjusting groove (7) is provided in the stepped groove (32), a sensing plate (71) is slidably connected in the adjusting groove (7), a second elastic member (72) is provided between the sensing plate (71) and the adjusting groove (7), a plurality of slots (33) are provided on both sides of the bottom of the tower plate (3), a clamping block (413) and a positioning block (423) matching the slots (33) are fixed on both sides of the fixed plate (411) and the movable plate (421), a flow channel (73) communicating with the adjusting groove (7) is provided on the clamping block (413), a plurality of the first elastic members (44) are multi-stage telescopic cylinders and are respectively fixed on the clamping block (413), the bottom of the multi-stage telescopic cylinders is communicated with the flow channel (73), and a connecting pipe (74) is provided between two multi-stage telescopic cylinders along the length direction of the tower plate (3).

8. A double-tower nitrous oxide purification process according to claim 7, characterized in that: A sealing ring (75) is provided on the outer wall of the sensing plate (71).

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