An electronic-grade nitric acid preparation device and method based on temperature difference control of filtration speed

Abstract

The present invention discloses an electronic-grade nitric acid preparation device and method based on temperature difference control of filtration speed, which relates to the technical field of nitric acid preparation. The electronic-grade nitric acid preparation device includes a primary rectification tower and a secondary rectification tower. An evaporator I and an evaporator II are respectively arranged on the outer sides of the bottoms of the primary rectification tower and the secondary rectification tower. Compared with the current filtration component, the present invention is provided with a temperature control component, which has a dual function. On the one hand, it preheats the liquefied nitric acid entering the filter. On the other hand, it changes the filtration speed of the filtration component for nitric acid as needed to prevent the evaporation process in the evaporator II from being unstable due to the too-fast flow of the liquefied nitric acid. In addition, the present invention precisely rotates the packing disc through a reversing motor to isolate the target storage cavity from the rectification tower body, avoiding the risk of the destruction of the negative pressure in the tower or the leakage of harmful gases during the traditional disassembly process.

Description

Technical Field

[0001] The present invention relates to the technical field of nitric acid preparation, and specifically to an electronic-grade nitric acid preparation device and method based on temperature difference control of filtration speed. Background Art

[0002] Electronic-grade nitric acid is a high-purity nitric acid, mainly used in the electronics industry as a core chemical for high-end electronics industries such as semiconductor manufacturing and photovoltaic cells. Traditional electronic-grade nitric acid preparation processes usually involve multiple stages of evaporation, rectification, and filtration. The stability of the filtration and evaporation processes directly affects the quality of the final product.

[0003] For example, the patents "CN113353900A An Electronic-Grade Nitric Acid Preparation Device" and "CN116946987A An Electronic-Grade Nitric Acid Preparation Device and Its Preparation Process" respectively disclose a technical solution for the preparation of electronic-grade nitric acid. However, the existing preparation processes still have the following defects in practical applications. First, in the filtration section, conventional devices lack precise control over the temperature of liquefied nitric acid. When the low-temperature liquefied nitric acid after condensation directly enters the secondary evaporator, it is extremely easy to cause thermal stress shock to the equipment due to excessive temperature difference, which not only shortens the service life of key components but also leads to fluctuations in the evaporation rate. In addition, most existing filters adopt a fixed flow rate design or rely on mechanical speed control devices (such as electric valves). The former cannot meet the requirements of dynamic changes in process parameters, and the latter has a risk of seal failure because the rotating shaft penetrates the container wall, which may cause leakage of nitric acid vapor and pose a safety hazard. Finally, in the process of replacing the packing in the rectification column, the existing technology generally adopts the method of shutting down and disassembling. This process not only destroys the negative pressure environment inside the tower, causing harmful gases to escape, but also consumes a large amount of time due to system restart. Summary of the Invention

[0004] The purpose of the present invention is to provide an electronic-grade nitric acid preparation device and method based on temperature difference control of filtration speed to solve the problems raised in the existing technology.

[0005] To achieve the above purpose, the present invention provides the following technical solution: An electronic-grade nitric acid preparation device based on temperature difference control of filtration speed. The electronic-grade nitric acid preparation device includes a primary rectification column and a secondary rectification column. An evaporator and a secondary evaporator are respectively arranged on the outer sides of the bottoms of the primary rectification column and the secondary rectification column. A condenser and a filter are connected between the primary rectification column and the secondary rectification column. An installation seat and a filtration component are arranged inside the filter, and a temperature control component is arranged inside the installation seat. When the present invention works, the nitric acid solution to be purified is pumped out from the raw material tank by a raw material pump and transported into the primary evaporator. The primary evaporator heats the nitric acid solution to be purified. At this time, the nitric acid solution vaporizes into steam, and the nitric acid steam is transported into the primary rectification column through a pipeline.

[0006] Furthermore, the primary rectification column comprises a column barrel and a base. A plurality of column barrels are provided and are sequentially installed above the base. A plurality of groups of packing components are arranged inside each column barrel. The structure and internal arrangement of the secondary rectification column are the same as those of the primary rectification column. Nitric acid vapor flows upward in the primary rectification column, and impurities such as acid foam and particulate matter in the nitric acid vapor are intercepted by the plurality of groups of packing components. When the nitric acid vapor reaches the top of the primary rectification column, it enters the condenser. The high-boiling-point vapor phase, which is the doped solution, is first liquefied in the condenser and then flows back into the primary rectification column. The low-boiling-point vapor phase is the purified nitric acid vapor. After the nitric acid vapor is liquefied, it flows into the filter (the functions realized by the condenser belong to conventional technical means in the art, and the specific structure is not described).

[0007] Furthermore, a diversion channel is arranged at the middle position of the mounting seat. The diversion channel is connected to the condenser through a liquid inlet pipe. A liquid outlet pipe is arranged at the bottom of the filter. The liquid outlet pipe is connected to the secondary evaporator. The filtering component comprises a chassis, two filter meshes, two fixing frames, a preheating rod and two movable plates. The two fixing frames and the two filter meshes are connected end to end along the circumference of the chassis to form an annular structure. The two movable plates are oppositely arranged outside the two fixing frames. The temperature control component is connected to the preheating rod and the two movable plates. When the liquefied nitric acid enters the filter, it flows along the liquid inlet pipe, the diversion channel and the filtering component. Residual impurities and crystallized substances in the liquefied nitric acid are intercepted by the two filter meshes. The filtered liquefied nitric acid flows into the secondary evaporator along the liquid outlet pipe.

[0008] Further, the temperature control component includes a movable groove, a gas storage tank, a cover plate and an annular turntable. The movable groove, the gas storage tank and the annular turntable are all arranged at the lower end of the mounting seat. The cover plate is arranged below the mounting seat. The annular turntable is connected to the two movable plates. There are bumps on the outer side of the annular turntable. An arc spring is arranged in the movable groove. An arc groove is arranged between the movable groove and the gas storage tank. An arc rod is arranged in the arc groove. The bumps on the outer side of the annular turntable are connected to the arc rod and the arc spring. A first heating element and a second heating element are arranged inside the gas storage tank. The first heating element is connected to the preheating rod through a heat conducting element. Compressed gas is filled below the second heating element. When liquefied nitric acid is filtered in the filter, the staff can supply heat to the preheating rod through the first heating element and the heat conducting element, so as to achieve the purpose of preheating the liquefied nitric acid. When the staff needs to adjust the filtering speed of the filtering component for nitric acid, the second heating element can be turned on to heat the compressed gas in the gas storage tank through the second heating element. At this time, the compressed gas will expand. Under the action of the compressed gas, the arc rod will push the annular turntable to rotate, drive the two movable plates to rotate synchronously through the annular turntable, increase the flow resistance of the liquefied nitric acid through the two movable plates, and indirectly change the filtering speed of the filtering component for nitric acid. Compared with the current method of controlling the filtering speed by means of a motor, etc., the present invention controls the filtering speed by adjusting the heating power to change the expansion volume of the gas, which can effectively reduce the mechanical sealing requirements of the rotating components (for example, the motor shaft often needs to pass through the container wall), and reduce the risk of nitric acid volatilization and leakage.

[0009] Further, a second channel is arranged on one side of each filter screen away from the axis of the chassis. A cleaning pipe is arranged below each second channel. A sealing ball is arranged inside each second channel. Each sealing ball is movably installed in the second channel through a first sealing spring.

[0010] Furthermore, a first channel is provided at a middle position of the chassis, a waste pipe is provided below the first channel, a mounting groove is provided at a middle position of the first channel, a sealing plate is provided in the mounting groove, a through hole is provided on the sealing plate, the sealing plate and the mounting groove are connected by a second sealing spring, one end of the sealing plate away from the second sealing spring is connected to one of the second channels by a push rod, the elastic coefficient of the second sealing spring is smaller than that of the first sealing spring, when liquefied nitric acid is filtered in the filter, the sealing ball is in close contact with the second channel, there is no overlapping area between the through hole on the sealing plate and the first channel, the first channel and the second channel are sealed by the sealing plate and the sealing ball to prevent leakage of liquefied nitric acid, and when the work is completed, if the staff needs to clean the filter screen in the filter, they only need to connect the cleaning pipe to the external cleaning system and connect the waste pipe to the external waste liquid return The collection system is connected, and then the temperature control group is turned on to rotate the two movable plates until the two movable plates are aligned with the two filter screens. The filter assembly is separated from the filter by the two movable plates and the two fixed frames. Then the staff can turn on the external cleaning system. Since the elastic coefficient of the second sealing spring is smaller than that of the first sealing spring, when the cleaning liquid enters the second channel, under the action of the hydraulic pressure, the second sealing spring will first deform. At this time, the through hole on the sealing plate will overlap with the first channel. When the external cleaning system continues to transport cleaning liquid into the second channel, the sealing ball will eventually detach from the second channel. Finally, the second channel is in an open state, and the cleaning liquid will enter the area between the movable plate and the filter screen. The filter screen can be flushed with the cleaning liquid. Finally, the impurities retained by the filter screen will follow the cleaning liquid along the first channel and the waste pipe into the external waste liquid recovery system, so as to facilitate the subsequent reuse of the filter.

[0011] Furthermore, each tower is provided with a plurality of groups of material changing ports, each group of material changing ports is aligned with a group of packing components, and a group of sealing end covers are detachably installed inside each group of material changing ports.

[0012] Furthermore, the filler assembly includes a mounting frame and a filler tray, the filler tray is arranged inside the mounting frame, and a plurality of storage cavities are arranged inside the filler tray. A group of support nets are arranged at the upper and lower ends of each group of storage cavities, and each group of storage cavities is filled with fillers.

[0013] Further, one end of the mounting frame close to the charging port is provided with a first opening. Two groups of partition plates are arranged at one end of the mounting frame close to the first opening inside. The packing tray is located between the two groups of partition plates. One group of second openings is arranged at one end of each storage cavity close to the inner wall of the mounting frame. A sealing cover is arranged on one of the partition plates. A reversing motor is arranged inside the sealing cover. The working end of the reversing motor is connected to the packing tray. When nitric acid vapor flows in the primary rectification tower, the particulate matter and acid foam in the nitric acid vapor are intercepted by the packing in the storage cavity. When the staff needs to replace the packing in a certain storage cavity, only need to start the reversing motor. The reversing motor can drive the packing tray to rotate in the mounting frame. When the storage cavity to be replaced with packing moves between the two groups of partition plates, the storage cavity to be replaced with packing can be separated from the primary rectification tower through the two groups of partition plates. At this time, the staff can first remove the sealing end cover from the charging port, and then use a suction pump to pump away the residual nitric acid vapor inside the storage cavity to be replaced with packing. Then the staff can directly clean the storage cavity to be replaced with packing and send new packing into the cleaned storage cavity. Compared with the current packing assembly, the present invention accurately rotates the packing tray through the reversing motor to isolate the target storage cavity from the main body of the rectification tower, avoiding the risk of negative pressure damage or harmful gas leakage in the tower during the traditional disassembly process. Each storage cavity adopts a standardized packing module, which improves the rate of replacing the packing on the one hand, and enables the present invention to replace the packing without shutting down the machine when there is a problem with the packing on the other hand.

[0014] A preparation method used in an electronic-grade nitric acid preparation device based on temperature difference control of the filtration rate includes the following steps:

[0015] S1: The nitric acid raw material is transported to the primary evaporator by a raw material pump. The generated vapor-phase nitric acid is transported to the primary rectification tower through a pipeline. Particulate matter and other impurities in the vapor-phase nitric acid are intercepted by the packing assembly arranged inside the primary rectification tower;

[0016] S2: The rectified nitric acid vapor is cooled and liquefied by a condenser. The liquefied nitric acid is filtered twice by a filter and enters the secondary evaporator;

[0017] S3: The nitric acid is reheated by the secondary evaporator. After the nitric acid becomes vapor-phase, it enters the secondary rectification tower through a pipeline. Particulate matter and other impurities in the vapor-phase nitric acid are intercepted by the packing assembly arranged inside the secondary rectification tower;

[0018] S4: The nitric acid vapor after secondary rectification is transported to the subsequent absorption tower treatment process through a pipeline.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. Compared with the current filter component, the present invention is provided with a temperature control component, which has a dual function. On the one hand, the preheating rod generates heat to preheat the liquefied nitric acid entering the filter, avoiding the direct entry of the low-temperature liquefied nitric acid after condensation into the secondary evaporator, which may cause thermal shock to the equipment, affect the service life and stability of the equipment, and enabling the liquefied nitric acid to quickly reach the evaporation state after entering the secondary evaporator. On the other hand, the temperature control component can also control the rotation of two movable plates, thereby increasing the flow resistance of the liquefied nitric acid as needed, indirectly changing the filtration speed of the filter component for nitric acid, preventing the unstable evaporation process in the secondary evaporator due to the too-fast flow of the liquefied nitric acid, affecting the evaporation effect of nitric acid, and causing the purification efficiency and quality of nitric acid to decline.

[0021] 2. The present invention can achieve the purpose of automatically cleaning the filter component through the mutual cooperation of the temperature control component and the filter component. When the liquefied nitric acid is filtered in the filter, the first channel and the second channel are sealed by the sealing plate and the sealing ball, effectively avoiding the leakage of the liquefied nitric acid. When it is necessary to clean the filter screen inside the filter component after the work is completed, only need to connect the cleaning pipe to the external cleaning system and the waste pipe to the external waste liquid recovery system, and then turn on the temperature control component, so that the cleaning liquid conveyed by the external cleaning system can flush the filter screen. The impurities intercepted by the filter screen will enter the external waste liquid recovery system along with the cleaning liquid through the first channel and the waste pipe. This operation method can quickly and effectively clean the filter screen, facilitate the reuse of the filter in the future, reduce the downtime of the equipment, and improve the production efficiency.

[0022] 3. Compared with the current packing component, the present invention accurately rotates the packing disk through a reversing motor to isolate the target storage cavity from the main body of the rectifying column, avoiding the risk of negative pressure damage or harmful gas leakage in the column during the traditional disassembly process. In addition, each storage cavity adopts a standardized packing module, which improves the rate of replacing the packing on the one hand, and enables the present invention to replace the packing without stopping the machine when there is a problem with the packing on the other hand, further improving the production efficiency and ensuring the continuity of production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the overall structural schematic diagram of the present invention;

[0024] Figure 2 is the internal structural schematic diagram of the filter of the present invention;

[0025] Figure 3 is the structural schematic diagram of the filter component of the present invention;

[0026] Figure 4 is the internal structural schematic diagram of the mounting seat of the present invention;

[0027] Figure 5Schematic structural diagram of the temperature control component of the present invention;

[0028] Figure 6 Schematic internal structure diagram of the chassis of the present invention;

[0029] Figure 7 Schematic position diagram of the packing component of the present invention;

[0030] Figure 8 Schematic structural diagram of the packing component of the present invention;

[0031] Figure 9 Schematic structural diagram of the mounting bracket of the present invention;

[0032] Figure 10 Schematic structural diagram of the packing tray of the present invention.

[0033] In the figure: 1, primary evaporator; 2, primary rectification tower; 21, tower barrel; 211, refueling port; 212, mounting bracket; 2121, partition board; 213, sealing cover; 214, packing tray; 2141, storage cavity; 2142, support mesh; 22, base; 3, condenser; 4, filter; 41, liquid inlet pipe; 42, mounting seat; 421, first heating element; 422, second heating element; 423, gas storage tank; 424, cover plate; 425, annular turntable; 426, arc rod; 43, liquid outlet pipe; 44, waste pipe; 45, cleaning pipe; 46, filtering component; 461, chassis; 4611, first channel; 4612, sealing plate; 4613, sealing ball; 4614, second channel; 4615, mounting groove; 462, filter screen; 463, fixing frame; 464, preheating rod; 465, movable plate; 5, secondary evaporator; 6, secondary rectification tower. Specific embodiments

[0034] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0035] Embodiment: As Figures 1-10As shown in the figure, the present invention provides a technical solution, an electronic-grade nitric acid preparation device based on temperature difference control of filtration speed. The electronic-grade nitric acid preparation device includes a primary rectification column 2 and a secondary rectification column 6. An evaporator 1 and a secondary evaporator 5 are respectively arranged on the outer sides of the bottoms of the primary rectification column 2 and the secondary rectification column 6. A condenser 3 and a filter 4 are connected between the primary rectification column 2 and the secondary rectification column 6. An installation seat 42 and a filter assembly 46 are arranged inside the filter 4. A temperature control assembly is arranged inside the installation seat 42. When the present invention works, the nitric acid solution to be purified is pumped out from the raw material tank by a raw material pump and conveyed into the primary evaporator 1. The primary evaporator 1 heats the nitric acid solution to be purified. At this time, the nitric acid solution vaporizes into steam, and the nitric acid steam is conveyed into the primary rectification column 2 through a pipeline.

[0036] As Figure 1 , Figure 7 shown, the primary rectification column 2 includes a column barrel 21 and a base 22. A plurality of column barrels 21 are provided, and the plurality of column barrels 21 are sequentially installed above the base 22. A plurality of groups of packing components are arranged inside each column barrel 21. The structure and the internal structure of the secondary rectification column 6 are the same as those of the primary rectification column 2.

[0037] The nitric acid steam flows upward in the primary rectification column 2, and impurities such as acid foam and particulate matter in the nitric acid steam are intercepted by a plurality of groups of packing components. When the nitric acid steam reaches the top of the primary rectification column 2, it will enter the condenser 3. The high-boiling-point vapor phase is the doped solution and is first liquefied in the condenser 3 and then flows back into the primary rectification column 2. The low-boiling-point vapor phase is the purified nitric acid steam. After the nitric acid steam is liquefied, it will flow into the filter 4 (the function realized by the condenser 3 belongs to the conventional technical means in the art, and the specific structure will not be described).

[0038] As Figures 2-6 shown, a diversion channel is arranged at the middle position of the installation seat 42. The diversion channel is connected to the condenser 3 through a liquid inlet pipe 41. An outlet pipe 43 is arranged at the bottom of the filter 4. The outlet pipe 43 is connected to the secondary evaporator 5. The filter assembly 46 includes a chassis 461, two filter meshes 462, two fixing frames 463, a preheating rod 464 and two movable plates 465. The two fixing frames 463 and the two filter meshes 462 are connected end to end along the circumference of the chassis 461 to form an annular structure. The two movable plates 465 are oppositely arranged on the outer sides of the two fixing frames 463. The temperature control assembly is connected to the preheating rod 464 and the two movable plates 465.

[0039] When the liquefied nitric acid enters the filter 4, it flows along the liquid inlet pipe 41, the diversion channel, and the filter assembly 46. The residual impurities and crystals in the liquefied nitric acid are intercepted by the two filter meshes 462. The filtered liquefied nitric acid flows into the secondary evaporator 5 along the liquid outlet pipe 43. Compared with the current filter components, the present invention is provided with a temperature control component. On the one hand, the preheating rod 464 is heated by the temperature control component, so as to preheat the liquefied nitric acid so that the liquefied nitric acid can quickly reach the evaporation state after entering the secondary evaporator 5, avoiding the thermal shock to the equipment caused by the direct entry of low-temperature nitric acid into the secondary evaporator 5. On the other hand, the temperature control component can also control the rotation of the two movable plates 465. By the two movable plates 465, the flow resistance of the liquefied nitric acid can be increased, and then the filtration speed of the filter assembly 46 for nitric acid can be indirectly changed, ensuring that the condensed nitric acid can smoothly enter the secondary evaporation stage and avoiding too fast filtration speed, which affects the evaporation effect of the condensed nitric acid by the subsequent secondary evaporator 5.

[0040] As Figures 2-6 shown, the temperature control component includes a movable groove, a gas storage tank 423, a cover plate 424, and an annular turntable 425. The movable groove, the gas storage tank 423, and the annular turntable 425 are all arranged at the lower end of the mounting seat 42. The cover plate 424 is arranged below the mounting seat 42. The annular turntable 425 is connected to the two movable plates 465. There are bumps on the outer side of the annular turntable 425. An arc-shaped spring is arranged in the movable groove. An arc-shaped groove is arranged between the movable groove and the gas storage tank 423. An arc-shaped rod 426 is arranged in the arc-shaped groove. The bump on the outer side of the annular turntable 425 is connected to the arc-shaped rod 426 and the arc-shaped spring. A first heating element 421 and a second heating element 422 are arranged inside the gas storage tank 423. The first heating element 421 is connected to the preheating rod 464 through a heat-conducting element. Compressed gas is filled below the second heating element 422.

[0041] When the liquefied nitric acid is filtered in the filter 4, the staff can supply heat to the preheating rod 464 through the first heating element 421 and the heat-conducting element, so as to achieve the purpose of preheating the liquefied nitric acid. When the staff needs to adjust the filtration speed of the filter assembly 46 for nitric acid, the second heating element 422 can be turned on. The second heating element 422 heats the compressed gas in the gas storage tank 423. At this time, the compressed gas will expand. Under the action of the compressed gas, the arc-shaped rod 426 will push the annular turntable 425 to rotate. The two movable plates 465 are driven by the annular turntable 425 to rotate synchronously. By the two movable plates 465, the flow resistance of the liquefied nitric acid is increased, and then the filtration speed of the filter assembly 46 for nitric acid is indirectly changed. Compared with the current method of controlling the filtration speed by means of a motor, etc., the present invention controls the filtration speed by adjusting the heating power to change the expansion volume of the gas, which can effectively reduce the mechanical sealing requirements of the rotating components (for example, the motor shaft often needs to pass through the container wall), and reduce the risk of nitric acid volatilization and leakage.

[0042] like Figure 6 As shown, a second channel 4614 is provided on the side of each filter 462 away from the axis of the chassis 461, a cleaning pipe 45 is provided below each second channel 4614, a sealing ball 4613 is provided inside each second channel 4614, and each sealing ball 4613 is movably installed in the second channel 4614 through a first sealing spring.

[0043] like Figure 6 As shown, a first channel 4611 is provided at the middle position of the chassis 461, a waste pipe 44 is provided below the first channel 4611, a mounting groove 4615 is provided at the middle position of the first channel 4611, a sealing plate 4612 is provided in the mounting groove 4615, a through hole is provided on the sealing plate 4612, the sealing plate 4612 and the mounting groove 4615 are connected by a second sealing spring, one end of the sealing plate 4612 away from the second sealing spring is connected to one of the second channels 4614 through a push rod, and the elastic coefficient of the second sealing spring is smaller than that of the first sealing spring.

[0044] When the liquefied nitric acid is filtered in the filter 4, the sealing ball 4613 is in close contact with the second channel 4614, and there is no overlapping area between the through hole on the sealing plate 4612 and the first channel 4611. The first channel 4611 and the second channel 4614 are sealed by the sealing plate 4612 and the sealing ball 4613 to prevent leakage of the liquefied nitric acid. When the work is completed, if the staff needs to clean the filter screen 462 in the filter 4, they only need to connect the cleaning pipe 45 to the external cleaning system, connect the waste pipe 44 to the external waste liquid recovery system, and then turn on the temperature control group to rotate the two movable plates 465 until the two movable plates 465 are aligned with the two filter screens 462, and separate the filter assembly 46 from the filter 4 through the two movable plates 465 and the two fixed frames 463. Then the staff The staff can turn on the external cleaning system. Since the elastic coefficient of the second sealing spring is smaller than that of the first sealing spring, when the cleaning liquid enters the second channel 4614, the second sealing spring will be deformed first under the action of hydraulic pressure. At this time, the through hole on the sealing plate 4612 will overlap with the first channel 4611. When the external cleaning system continues to transport cleaning liquid into the second channel 4614, the sealing ball 4613 will eventually detach from the second channel 4614. Finally, the second channel 4614 is in an open state, and the cleaning liquid will enter the area between the movable plate 465 and the filter screen 462. The filter screen 462 can be rinsed with the cleaning liquid. Finally, the impurities retained by the filter screen 462 will enter the external waste liquid recovery system along the first channel 4611 and the waste pipe 44 with the cleaning liquid, so as to facilitate the subsequent reuse of the filter 4.

[0045] like Figure 1 , Figure 7As shown, a number of groups of charging openings 211 are provided on each tower barrel 21. Each group of charging openings 211 is aligned with a group of packing components, and a group of sealing end caps can be detachably installed inside each group of charging openings 211.

[0046] As Figure 1 , Figures 7-10 shown, the packing component includes a mounting frame 212 and a packing tray 214. The packing tray 214 is arranged inside the mounting frame 212. A number of groups of material storage cavities 2141 are arranged inside the packing tray 214. A group of support meshes 2142 are arranged at both the upper and lower ends of each group of material storage cavities 2141, and each group of material storage cavities 2141 is filled with packing.

[0047] As Figure 1 , Figures 7-10 shown, one end of the mounting frame 212 close to the charging opening 211 is provided with a first opening. Two groups of partition plates 2121 are arranged at one end inside the mounting frame 212 close to the first opening. The packing tray 214 is located between the two groups of partition plates 2121. A group of second openings are arranged at one end of each group of material storage cavities 2141 close to the inner wall of the mounting frame 212. A sealing cover 213 is arranged on one of the partition plates 2121, and a reversing motor is arranged inside the sealing cover 213. The working end of the reversing motor is connected to the packing tray 214.

[0048] When nitric acid vapor flows in the primary distillation column 2, the particulate matter and acid foam in the nitric acid vapor are intercepted by the packing in the material storage cavity 2141. When the staff needs to replace the packing in a certain group of material storage cavities 2141, only need to start the reversing motor. The reversing motor can drive the packing tray 214 to rotate in the mounting frame 212. When the material storage cavity 2141 with the packing to be replaced moves between the two groups of partition plates 2121, the two groups of partition plates 2121 can separate the material storage cavity 2141 with the packing to be replaced from the primary distillation column 2. At this time, the staff can first remove the sealing end cap from the charging opening 211, and then use a suction pump to pump away the residual nitric acid vapor inside the material storage cavity 2141 with the packing to be replaced. Then the staff can directly clean the material storage cavity 2141 with the packing to be replaced and send new packing into the cleaned material storage cavity 2141. Compared with the current packing components, the present invention accurately rotates the packing tray 214 through the reversing motor to isolate the target material storage cavity 2141 from the main body of the distillation column, avoiding the risk of negative pressure damage or harmful gas leakage in the tower during the traditional disassembly process. Each material storage cavity 2141 adopts a standardized packing module, which on the one hand improves the rate of packing replacement, and on the other hand enables the present invention to replace the packing without stopping the machine when problems are found with the packing.

[0049] A preparation method used in an electronic-grade nitric acid preparation device based on temperature difference control of the filtration rate includes the following steps:

[0050] S1: The nitric acid raw material is transported to the first-stage evaporator 1 by a raw material pump. The generated vapor-phase nitric acid is transported to the first-stage rectification tower 2 through a pipeline. Particulate matter and other impurities in the vapor-phase nitric acid are intercepted by the packing components arranged inside the first-stage rectification tower 2.

[0051] S2: The rectified nitric acid vapor is cooled and liquefied by the condenser 3. The liquefied nitric acid is filtered twice by the filter 4 and enters the second-stage evaporator 5.

[0052] S3: The nitric acid is reheated by the second-stage evaporator 5. After the nitric acid becomes vapor-phase, it enters the second-stage rectification tower 6 through a pipeline. Particulate matter and other impurities in the vapor-phase nitric acid are intercepted by the packing components arranged inside the second-stage rectification tower 6.

[0053] S4: The vapor of the nitric acid after secondary rectification is transported to the subsequent absorption tower treatment process through a pipeline.

[0054] The working principle of the present invention: The nitric acid solution to be purified is pumped out from the raw material tank by a raw material pump and transported into the first-stage evaporator 1. The first-stage evaporator 1 heats the nitric acid solution to be purified. At this time, the nitric acid solution vaporizes into steam. The nitric acid steam is transported to the first-stage rectification tower 2 through a pipeline. When the nitric acid steam flows inside the first-stage rectification tower 2, particulate matter and acid foam in the nitric acid steam are intercepted by the packing in the storage cavity 2141. When the staff needs to replace the packing in a certain storage cavity 2141 inside the packing component, the reversing motor can be started to isolate the target storage cavity 2141 from the main body of the first-stage rectification tower 2. Then, the staff can first remove the sealing end cover from the material replacement port 211, and use an air extraction pump to extract the residual nitric acid steam inside the target storage cavity 2141. Then, directly clean the storage cavity 2141 of the packing to be replaced, and send the new packing into the cleaned storage cavity 2141. When the nitric acid steam reaches the top of the first-stage rectification tower 2, it will enter the condenser 3. The high-boiling-point vapor-phase doped solution is first liquefied in the condenser 3 and flows back to the first-stage rectification tower 2. The low-boiling-point vapor-phase is the purified nitric acid steam. After the nitric acid steam is liquefied, it will flow into the filter 4 and flow along the liquid inlet pipe 41, the diversion channel, and the filter component 46. The filter component 46 intercepts the residual impurities and crystals in the liquefied nitric acid. The temperature control component controls the filtering speed of the filter component 46 for nitric acid to ensure that the condensed nitric acid can smoothly enter the secondary evaporation stage, avoiding a too fast filtering speed and affecting the evaporation effect of the condensed nitric acid by the subsequent second-stage evaporator 5. When the filtered liquefied nitric acid is reheated in the second-stage evaporator 5, the nitric acid steam will enter the second-stage rectification tower 6 through a pipeline. Particulate matter and other impurities in the vapor-phase nitric acid are intercepted by the packing components arranged inside the second-stage rectification tower 6. The vapor of the nitric acid after secondary rectification is transported to the subsequent absorption tower treatment process through a pipeline.

[0055] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An electronic-grade nitric acid preparation device based on temperature difference control of filtration speed, characterized in that: The electronic grade nitric acid preparation device includes a primary distillation column (2) and a secondary distillation column (6). An evaporator I (1) and an evaporator II (5) are respectively arranged on the outer sides of the bottoms of the primary distillation column (2) and the secondary distillation column (6). A condenser (3) and a filter (4) are connected between the primary distillation column (2) and the secondary distillation column (6). An installation seat (42) and a filtering component (46) are arranged inside the filter (4). A temperature control component is arranged inside the installation seat (42) to preheat the condensed nitric acid and control the filtering speed of the filtering component (46). The filtering component (46) includes a chassis (461), two filter meshes (462), two fixing frames (463), a preheating rod (464) and two movable plates (465). The two fixing frames (463) and the two filter meshes (462) are connected end to end along the circumference of the chassis (461) to form an annular structure. The two movable plates (465) are oppositely arranged on the outer sides of the two fixing frames (463). The temperature control component is connected to the preheating rod (464) and the two movable plates (465). The temperature control component includes a movable groove, an air storage tank (423), a cover plate (424) and an annular turntable (425). The movable groove, the air storage tank (423) and the annular turntable (425) are all arranged at the lower end of the installation seat (42). The cover plate (424) is arranged below the installation seat (42). The annular turntable (425) is connected to the two movable plates (465). A convex block is arranged on the outer side of the annular turntable (425). An arc-shaped spring is arranged in the movable groove. An arc-shaped groove is arranged between the movable groove and the air storage tank (423). An arc-shaped rod (426) is arranged in the arc-shaped groove. The convex block on the outer side of the annular turntable (425) is connected to the arc-shaped rod (426) and the arc-shaped spring. A first heating element (421) and a second heating element (422) are arranged inside the air storage tank (423). The first heating element (421) is connected to the preheating rod (464) through a heat conduction element. Compressed gas is filled below the second heating element (422).

2. The electronic grade nitric acid preparation device based on temperature difference control of filtration speed according to claim 1, wherein: The primary distillation column (2) includes a column barrel (21) and a base (22). A plurality of column barrels (21) are arranged. The plurality of column barrels (21) are sequentially installed above the base (22). A plurality of groups of packing components are arranged inside each column barrel (21). The structure and the internal structure of the secondary distillation column (6) are the same as those of the primary distillation column (2).

3. The electronic grade nitric acid preparation device based on temperature difference control of filtration speed according to claim 1, wherein: A second channel (4614) is arranged on one side of each filter mesh (462) away from the axis of the chassis (461). A cleaning pipe (45) is arranged below each second channel (4614). A sealing ball (4613) is arranged inside each second channel (4614). Each sealing ball (4613) is movably installed in the second channel (4614) through a first sealing spring.

4. The electronic grade nitric acid preparation device based on temperature difference control of filtration rate according to claim 3, characterized in that: A first channel (4611) is provided at the middle position of the chassis (461). A waste pipe (44) is provided below the first channel (4611). An installation groove (4615) is provided at the middle position of the first channel (4611). A sealing plate (4612) is arranged in the installation groove (4615). A through hole is provided on the sealing plate (4612). The sealing plate (4612) is connected to the installation groove (4615) through a second sealing spring. One end of the sealing plate (4612) away from the second sealing spring is connected to one of the second channels (4614) through a push rod.

5. The electronic grade nitric acid preparation device based on temperature difference control of filtration speed according to claim 2, wherein: A plurality of groups of charging openings (211) are provided on each tower barrel (21). Each group of charging openings (211) is aligned with a group of packing components. A group of sealing end caps are detachably installed inside each group of charging openings (211).

6. The electronic grade nitric acid preparation device based on temperature difference control of filtration rate according to claim 5, wherein: The packing component includes an installation frame (212) and a packing tray (214). The packing tray (214) is arranged inside the installation frame (212). A plurality of groups of material storage cavities (2141) are provided inside the packing tray (214). A group of support meshes (2142) are provided at the upper and lower ends of each group of material storage cavities (2141).

7. An electronic-grade nitric acid preparation device based on temperature difference control of filtration speed according to claim 6, characterized in that: One end of the installation frame (212) close to the charging opening (211) is provided with a first opening. Two groups of partition plates (2121) are provided at one end of the interior of the installation frame (212) close to the first opening. The packing tray (214) is located between the two groups of partition plates (2121). A group of second openings are provided at one end of each group of material storage cavities (2141) close to the inner wall of the installation frame (212). A sealing cover (213) is provided on one of the partition plates (2121). A reversing motor is arranged inside the sealing cover (213). The working end of the reversing motor is connected to the packing tray (214).

8. A preparation method of an electronic-grade nitric acid preparation device based on temperature difference control of filtration rate according to claim 2, characterized in that: Including the following steps: S1: The nitric acid raw material is transported to the first-stage evaporator (1) by a raw material pump. The generated vapor-phase nitric acid is transported to the first-stage rectifying column (2) through a pipeline. The particulate impurities in the vapor-phase nitric acid are intercepted by the packing component arranged inside the first-stage rectifying column (2). S2: The rectified nitric acid vapor is cooled and liquefied by the condenser (3). The liquefied nitric acid passes through the filter (4) for secondary filtration and enters the second-stage evaporator (5). S3: The nitric acid is heated secondarily by the second-stage evaporator (5). After the nitric acid becomes vapor-phase, it enters the second-stage rectifying column (6) through a pipeline. The particulate impurities in the vapor-phase nitric acid are intercepted by the packing component arranged inside the second-stage rectifying column (6). S4: The nitric acid vapor after secondary rectification is transported to the subsequent absorption tower treatment process through a pipeline.

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