Full-automatic production line for preparing high-purity electronic-grade nitric acid

Abstract

The application discloses a kind of preparation high-purity electronic grade nitric acid fully automatic production line, it is related to electronic grade nitric acid production line technical field, including purification tower, liquid distribution anti-hanging device, feed tank, pipe network assembly and tray.The application utilizes the blocking of hanging wall liquid falling path by flow ring, and makes the flow of hanging wall liquid converge into flow cavity for collection, then rises under the action of buoyancy by floating head, drives the synchronous upward movement of taper rod, so that hanging wall liquid enters secondary liquid distribution cavity, uses liquid distribution chute and flow guide head to guide the hanging wall liquid obliquely, makes hanging wall liquid away from tower wall and obliquely flows out, avoids causing secondary wall hanging.The taper rod is designed as inverted cone, so that when the taper rod moves up with the floating head, the gap between the taper rod and the falling port automatically increases, so that the water discharge gradually increases with the increase of hanging wall liquid, forming the effect of self-adapting liquid release and timely reducing the accumulation of hanging wall liquid;At the same time, the taper rod is limited by the limiting ring to prevent disengagement, and a passage is reserved for the liquid flow to ensure smooth falling of the liquid during adjustment.

Description

Technical Field

[0001] This invention relates to the field of electronic-grade nitric acid production line technology, specifically a fully automated production line for preparing high-purity electronic-grade nitric acid. Background Technology

[0002] With the increasing demands for wet cleaning, etching, and surface treatment processes in fields such as integrated circuits, display panels, and precision chemicals, electronic-grade nitric acid, as a key chemical, directly impacts the yield and reliability of subsequent processes due to its purity and stability. Compared to ordinary industrial nitric acid, electronic-grade nitric acid requires not only higher precision in acid concentration control but also stricter limits on trace metal ions, particulate matter, and dissolved organic matter. Currently, electronic-grade nitric acid is typically produced using fully automated production lines.

[0003] In existing electronic-grade nitric acid production lines, when purifying nitric acid, the verticality of the purification tower wall causes the liquid to be captured as soon as it touches the wall. Furthermore, the high porosity at the edges of the tower wall and packing results in low liquid resistance and high flow rate at these locations, leading to wall adhesion. This causes the gas and liquid phases to separate, and the central packing layer in the tower to dry out due to lack of liquid. This not only reduces the preparation efficiency but also increases the amount of byproducts. Summary of the Invention

[0004] The purpose of this invention is to provide a fully automated production line for preparing high-purity electronic-grade nitric acid, so as to solve the problem of easy wall adhesion at the purification tower wall in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a fully automated production line for preparing high-purity electronic-grade nitric acid, comprising a purification tower, a liquid distribution anti-fouling device, a control system, and a pipeline assembly, wherein the purification tower is connected to a reboiler and a condenser respectively through the pipeline assembly;

[0006] The liquid distribution anti-sag device includes a liquid distribution beam and a flow-gathering ring. The liquid distribution beam is installed inside the purification tower. Several liquid distribution chambers are installed at the bottom of the liquid distribution beam, and demister rings are installed between the liquid distribution chambers. The flow-gathering ring is installed inside the purification tower and has an inlet and outlet. Several float detectors are movably installed inside the flow-gathering ring. Several anti-overflow and backflow mechanisms are installed inside the purification tower and are connected to the flow-gathering ring. The flow-gathering ring is located below the liquid distribution chambers. Both the anti-overflow and backflow mechanisms and the float detectors are electrically connected to the control system.

[0007] The production line is equipped with a control cabinet, which houses the control system for operating the entire production line. The piping system contains several connecting pipes used to connect the various production components. The purification tower contains several trays filled with packing material.

[0008] Before operation, unrefined nitric acid raw material is mixed with production reagents in the feed tank to form raw acid. The control system controls the pumping device to transport the raw acid through the pipeline assembly to the inlet. The raw acid enters the primary distribution chamber in the distribution beam from the inlet. When the raw acid accumulates in the primary distribution chamber to the height of the distribution port, it begins to fall from the distribution port to the distribution bin below. Several leaks on the distribution bin evenly distribute the raw acid into several fine water columns. The water columns fall onto the packing and then fall into the reflux port at the bottom of the purification tower. Finally, they enter the reboiler for heating through the reflux port.

[0009] During this period, the control system activates the reboiler, which heats the pre-reserved raw acid inside, causing the nitric acid in the raw acid to absorb heat and form nitric acid gas. The nitric acid gas is then transported to the inlet through the pipeline assembly. After entering through the inlet, the nitric acid gas rises upward along the purification tower. During this process, the nitric acid gas continuously contacts the falling raw acid, and the impurities contained in the nitric acid gas are mixed and carried away by the low-temperature liquid raw acid. At the same time, the nitric acid in the raw acid is converted into gas after absorbing heat and rises. This cycle continues, and the high-purity nitric acid gas rises step by step until it enters the condenser from the outlet.

[0010] The condenser cools the gaseous nitric acid to form clean liquid nitric acid. Then, the control system sends this portion of nitric acid to the bleaching and nanofilters for deep purification to obtain high-purity electronic-grade nitric acid.

[0011] Furthermore, the inlet and outlet include a collection port and several liquid distribution troughs;

[0012] The collection port is located on the concentrating ring, which has a concentrating cavity. The bottom of the concentrating cavity has several drop ports. The float detector is movably installed on the drop ports. The bottom of the concentrating ring has a secondary liquid distribution cavity, which is connected to the concentrating cavity through the drop ports. The top of the secondary liquid distribution cavity has an overflow port, which is connected to the anti-overflow and backflow mechanism through the overflow port. Several liquid distribution troughs are located on the side of the secondary liquid distribution cavity away from the anti-overflow and backflow mechanism. The liquid distribution troughs are equipped with guide heads.

[0013] Furthermore, the float detector includes a cone rod and a connecting rod. The connecting rod is mounted on the current-collecting ring and has a protrusion. The cone rod is movably mounted on the descent port. A limit ring is installed at the bottom of the cone rod, and a float head is installed at the top of the cone rod. The float head contains a detection element. The cone rod adopts an inverted cone design.

[0014] The float head can float in the wall-mounted liquid. The inverted conical design of the cone rod causes the gap between the cone rod and the drop outlet to gradually increase as the cone rod rises, allowing the flow rate at the drop outlet to gradually increase with the rise of the cone rod. Furthermore, because the rise of the cone rod is consistent with the rise of the float head, the more wall-mounted liquid collected in the flow-collecting chamber, the higher the float head will lift the cone rod, thus achieving an adaptive adjustment function for the flow rate based on the increase of wall-mounted liquid. The limiting ring is designed to prevent the bottom of the cone rod from detaching from the drop outlet, while also ensuring that the falling wall-mounted liquid can flow freely, achieving both anti-detachment and smooth liquid flow.

[0015] When the raw acid flowing through the distribution chamber adheres to the tower wall, the adhered liquid falls along the inner wall of the purification tower. Upon reaching the collection ring, the collection port of the collection ring blocks the falling path and diverts the adhered liquid into the collection chamber. As the adhered liquid converges, the float head, under buoyancy, drives the float detector upwards. At this point, the falling port previously blocked by the float head opens, and the adhered liquid falls along the cone rod into the secondary distribution chamber, flowing evenly out through several distribution troughs. The guide head diagonally guides the outflowing adhered liquid, keeping it away from the tower wall and flowing out at an angle, thus preventing secondary adhesion and achieving a primary anti-adhesion effect.

[0016] Furthermore, the detection element includes a flexible contact and a protective diaphragm. The flexible contact is installed at the top of the float head, and a pressure head is provided at the bottom of the flexible contact. The protective diaphragms are symmetrically installed inside the float head, and piezoelectric elements are installed between the protective diaphragms.

[0017] The flexible contact is made of an elastic, corrosion-resistant material. When the flexible contact is compressed, it causes the pressure head to move downwards, which in turn compresses the piezoelectric element inside the protective diaphragm. The piezoelectric element generates an electrical signal after being compressed.

[0018] When the wall-mounted liquid exceeds the critical level, the liquid level in the concentrator ring continues to rise, causing the float head to rise to the height of the connecting rod under the action of buoyancy. The flexible contact on the float head contacts and squeezes against the protrusion on the connecting rod. After being pressed, the flexible contact head drives the pressure head to squeeze the piezoelectric body downward. After being pressed, the piezoelectric body generates an electrical signal. After receiving the electrical signal, the control system opens the telescopic rod. The output shaft of the telescopic rod drives the base plate to descend. The base plate drives the elastic bladder to open. The overflow chamber inside the elastic bladder expands rapidly, and the overflowing wall-mounted liquid flows into the overflow chamber from the overflow port.

[0019] At the same time, the control system reduces the conveying speed of the raw acid, thereby reducing the flow rate of the liquid distribution chamber and reducing the continuous increase of the wall-attached liquid. When the wall-attached liquid gradually decreases to below the critical value, the float detector descends, disconnects from the connecting rod, and the electrical signal disappears. Then, the control system controls the output shaft of the telescopic rod to slowly extend. The output shaft of the telescopic rod drives the bottom plate to squeeze the elastic bladder upward. After being compressed, the elastic bladder contracts, and the overflow liquid in the overflow chamber is squeezed in the opposite direction from the overflow port into the secondary liquid distribution chamber, and then discharged by the secondary liquid distribution, thereby achieving the effect of secondary anti-wall-attached liquid.

[0020] If the electrical signal persists and the wall-mounted object remains, the control system will send an alarm signal to the operator, who will then shut down the machine for inspection.

[0021] Furthermore, the anti-overflow and backflow mechanism includes an end shell and a connecting block. An elastic bladder is installed at the bottom of the end shell, and a base plate is installed at the bottom of the elastic bladder. The elastic bladder, end shell, and base plate form an overflow cavity. The overflow cavity is connected to the secondary liquid distribution cavity through an overflow port. The connecting block is installed inside the purification tower, and a telescopic rod is installed on the connecting block. The output shaft of the telescopic rod is connected to the base plate.

[0022] Furthermore, the demisting ring includes several connecting parts, which are installed between the liquid distribution chambers. Several vertical rings are installed on the connecting parts. An upper ring plate is installed on one side of the vertical ring, and a lower ring plate is installed on the other side of the vertical ring. An S-shaped demisting flow channel is formed between adjacent upper and lower ring plates.

[0023] When nitric acid gas reaches the liquid distribution and anti-fogging device from bottom to top, it passes through the demister ring and then through the S-shaped demister channel formed between the upper and lower ring plates. The water mist mixed in the nitric acid gas will adhere to the vertical ring, the upper ring plate, and the lower ring plate, thereby achieving the demister effect.

[0024] Furthermore, the purification tower has an outlet at the top, which is connected to the condenser through a pipeline assembly. The purification tower has a reflux port at the bottom, which is connected to the reboiler through a pipeline assembly. The purification tower also has an inlet, which is connected to the reboiler through a pipeline assembly. Additionally, the purification tower has a liquid inlet, one end of which is connected to a feed box through a pipeline assembly, and the other end of which is connected to a liquid separator beam.

[0025] Furthermore, the liquid distribution beam is provided with a primary liquid distribution chamber, which is connected to the liquid inlet. Several liquid distribution ports are provided on both sides of the primary liquid distribution chamber, and the liquid distribution ports are located above the liquid distribution chamber.

[0026] Furthermore, several leaks are provided at the bottom of the liquid distribution tank.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. The flow-collecting ring is used to block the falling path of the wall-mounted liquid and to collect the liquid flow into the flow-collecting cavity. Then, the floating head rises under the action of buoyancy, which drives the cone rod to move upward synchronously, so that the wall-mounted liquid enters the secondary liquid distribution cavity. The liquid distribution chute and the guide head are used to guide the wall-mounted liquid at an angle, so that the wall-mounted liquid is away from the tower wall and flows out at an angle, avoiding secondary wall-mounting and achieving the effect of primary anti-wall-mounting.

[0029] 2. The cone rod adopts an inverted cone design, which automatically increases the gap between the cone rod and the drop outlet when the cone rod moves up with the float. This allows the discharge volume to increase step by step as the amount of wall-mounted liquid increases, forming an adaptive liquid discharge effect and timely reducing the accumulation of wall-mounted liquid. At the same time, the limiting ring limits the cone rod to prevent it from detaching and reserves a channel for liquid flow, ensuring that the liquid continues to fall smoothly during the adjustment process without jamming or interruption.

[0030] 2. When the wall-mounted liquid exceeds the critical value, the displacement generated by buoyancy is converted into the compression between the protrusion and the floating head. An electrical signal is generated through the piezoelectric element, which allows the control system to identify and drive the elastic bladder to expand rapidly to form an overflow cavity, which can promptly accept the excess wall-mounted liquid. At the same time, the control system reduces the amount of raw acid transported to reduce the formation of wall-mounted liquid from the source, realizing precise control of rapid discharge and source flow restriction, and preventing the wall-mounted liquid from getting out of control.

[0031] 3. After the operating conditions are restored, the overflow liquid is squeezed back into the secondary liquid distribution chamber and then evenly distributed again through the liquid distribution chute, realizing the return distribution of the overflow liquid.

[0032] 4. When nitric acid gas passes through the S-shaped demister channel formed by the demister ring, the droplets adhere to and are trapped on the upper ring plate, lower ring plate and vertical ring, thereby reducing the risk of water mist being entrained into condensation.

[0033] 5. The raw acid is distributed in the liquid chamber to form multiple fine liquid columns that uniformly wet the packing material, achieving full countercurrent contact and washing with the rising nitric acid gas, reducing the dry zone of the packing material, and improving heat exchange and impurity removal efficiency. Attached Figure Description

[0034] Figure 1 This is a three-dimensional view of the fully automated production line of the present invention;

[0035] Figure 2 This is a cross-sectional view of the purification tower of the present invention;

[0036] Figure 3 This is a perspective view of the liquid-repellent anti-snagging device of the present invention;

[0037] Figure 4 This is a perspective view of the liquid distribution chamber and the demister ring of the present invention;

[0038] Figure 5 This is a cross-sectional view of the demister ring of the present invention;

[0039] Figure 6 This is a perspective view of the current-collecting ring, the anti-overflow and backflow mechanism, and the float detector of the present invention;

[0040] Figure 7 For the present invention Figure 6 A magnified view of a portion of region A in the middle;

[0041] Figure 8 For the present invention Figure 6A magnified view of a portion of region B in the middle;

[0042] Figure 9 This is a cross-sectional view of the float detector of the present invention;

[0043] Figure 10 For the present invention Figure 9 A magnified view of a portion of region C.

[0044] In the diagram: 1. Purification tower; 2. Liquid distribution anti-sag device; 3. Feed box; 4. Piping assembly; 5. Tower plate; 11. Liquid inlet; 12. Air inlet; 13. Reflux port; 14. Air outlet; 21. Liquid distribution beam; 22. Liquid distribution chamber; 23. Demisting ring; 24. Converging ring; 25. Anti-overflow and reflux mechanism; 26. Float detector; 211. Primary liquid distribution chamber; 212. Liquid distribution port; 221. Leak; 231. Vertical ring; 232. Upper ring plate; 233. Lower ring plate; 234. Demisting channel; 235. 241. Connector; 242. Collection port; 243. Converging chamber; 244. Drop port; 245. Liquid distribution chute; 246. Secondary liquid distribution chamber; 247. Overflow port; 248. Guide head; 261. Connecting rod; 262. Protrusion; 263. Floating head; 264. Conical rod; 265. Limiting ring; 266. Flexible contact; 267. Protective membrane; 268. Piezoelectric element; 269. Pressure head; 251. End shell; 252. Elastic bladder; 253. Base plate; 254. Telescopic rod; 255. Connecting block. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Example: Figures 1-10 As shown, the present invention provides a technical solution: a fully automated production line for preparing high-purity electronic-grade nitric acid, including a purification tower 1, a liquid distribution and anti-fouling device 2, a control system and a pipeline assembly 4. The purification tower 1 is connected to a reboiler and a condenser respectively through the pipeline assembly 4.

[0047] The liquid distribution anti-snagging device 2 includes a liquid distribution beam 21 and a flow-gathering ring 24. The liquid distribution beam 21 is installed inside the purification tower 1. Several liquid distribution chambers 22 are installed at the bottom of the liquid distribution beam 21. Demisting rings 23 are installed between the liquid distribution chambers 22. The flow-gathering ring 24 is installed inside the purification tower 1. The flow-gathering ring 24 has an inlet and outlet. Several float detectors 26 are movably installed inside the flow-gathering ring 24. Several anti-overflow and backflow mechanisms 25 are installed inside the purification tower 1. The anti-overflow and backflow mechanisms 25 are connected to the flow-gathering ring 24. The flow-gathering ring 24 is located below the liquid distribution chambers 22. The anti-overflow and backflow mechanisms 25 and the float detectors 26 are both electrically connected to the control system.

[0048] The production line is equipped with a control cabinet, which houses the control system for operating the entire production line. Piping assembly 4 contains several connecting pipes used to connect various production components. Purification tower 1 contains several trays 5, which are filled with packing material.

[0049] The purification tower 1 has an outlet 14 at the top, which is connected to the condenser through a pipe network assembly 4. The purification tower 1 has a reflux port 13 at the bottom, which is connected to the reboiler through the pipe network assembly 4. The purification tower 1 has an inlet 12, which is connected to the reboiler through the pipe network assembly 4. The purification tower 1 has a liquid inlet 11, one end of which is connected to a feed box 3 through the pipe network assembly 4, and the other end of which is connected to a liquid separator beam 21.

[0050] The liquid distribution beam 21 is provided with a primary liquid distribution chamber 211, which is connected to the liquid inlet 11. Several liquid distribution ports 212 are provided on both sides of the primary liquid distribution chamber 211, and the liquid distribution ports 212 are located above the liquid distribution chamber 22.

[0051] The liquid distribution chamber 22 has several leaks 221 at its bottom.

[0052] The demisting ring 23 includes several connectors 235, which are installed between liquid distribution chambers 22. Several vertical rings 231 are installed on the connectors 235. An upper ring plate 232 is installed on one side of the vertical ring 231, and a lower ring plate 233 is installed on the other side of the vertical ring 231. An S-shaped demisting channel 234 is formed between adjacent upper ring plates 232 and lower ring plates 233.

[0053] When nitric acid gas reaches the liquid distribution and anti-fogging device 2 from bottom to top, it will pass through the demister ring 23 and then through the S-shaped demister flow channel 234 formed between the upper ring plate 232 and the lower ring plate 233. The water mist mixed in the nitric acid gas will adhere to the vertical ring 231, the upper ring plate 232 and the lower ring plate 233, thereby achieving the demister effect.

[0054] The inlet and outlet include a collection port 241 and several liquid distribution troughs 244. The collection port 241 is set on the flow-gathering ring 24, the flow-gathering ring 24 is provided with a flow-gathering cavity 242, the bottom end of the flow-gathering cavity 242 is provided with several drop ports 243, the float detector 26 is movably installed on the drop ports 243, the bottom end of the flow-gathering ring 24 is provided with a secondary liquid distribution cavity 245, the secondary liquid distribution cavity 245 is connected to the flow-gathering cavity 242 through the drop ports 243, the top end of the secondary liquid distribution cavity 245 is provided with an overflow port 246, the secondary liquid distribution cavity 245 is connected to the anti-overflow and backflow mechanism 25 through the overflow port 246, and several liquid distribution troughs 244 are set on the side of the secondary liquid distribution cavity 245 away from the anti-overflow and backflow mechanism 25, and the liquid distribution troughs 244 are provided with guide heads 247.

[0055] The float detector 26 includes a cone rod 264 and a connecting rod 261. The connecting rod 261 is mounted on the current-collecting ring 24 and has a protrusion 262. The cone rod 264 is movably mounted on the drop port 243. A limit ring 265 is installed at the bottom of the cone rod 264 and a float head 263 is installed at the top of the cone rod 264. A detection element is provided inside the float head 263. The cone rod 264 adopts an inverted cone design.

[0056] The float 263 can float in the wall-mounted liquid. The inverted conical design of the cone 264 causes the gap between the cone 264 and the drop outlet 243 to gradually increase as the cone 264 rises, allowing the flow rate of the drop outlet 243 to gradually increase with the rise of the cone 264. Furthermore, because the rise of the cone 264 is consistent with the rise of the float 263, the more wall-mounted liquid collected in the flow-collecting cavity 242, the higher the float 263 drives the cone 264 to rise, thus achieving an adaptive adjustment function for the flow rate according to the increase of wall-mounted liquid. The limiting ring 265 is designed to prevent the bottom of the cone 264 from detaching from the drop outlet 243, while also ensuring that the falling wall-mounted liquid can flow freely, achieving both anti-detachment and smooth liquid flow.

[0057] The detection element includes a flexible contact 266 and a protective diaphragm 267. The flexible contact 266 is installed at the top of the float head 263, and a pressure head 269 is provided at the bottom of the flexible contact 266. The protective diaphragms 267 are symmetrically installed inside the float head 263, and piezoelectric elements 268 are installed between the protective diaphragms 267.

[0058] The flexible contact 266 is made of an elastic and corrosion-resistant material. When the flexible contact 266 is pressed, it will cause the pressure head 269 to move downward. The pressure head 269 will squeeze the piezoelectric element 268 inside the protective diaphragm 267, and the piezoelectric element 268 will generate an electrical signal after being compressed.

[0059] The anti-overflow and backflow mechanism 25 includes an end shell 251 and a connecting block 255. An elastic bladder 252 is installed at the bottom of the end shell 251, and a base plate 253 is installed at the bottom of the elastic bladder 252. The elastic bladder 252, the end shell 251 and the base plate 253 form an overflow chamber. The overflow chamber is connected to the secondary liquid distribution chamber 245 through the overflow port 246. The connecting block 255 is installed in the purification tower 1. A telescopic rod 254 is installed on the connecting block 255, and the output shaft of the telescopic rod 254 is connected to the base plate 253.

[0060] The working principle of this invention is as follows: Before operation, unrefined nitric acid raw material is mixed with production reagents in the feed tank 3 to form raw acid. The control system controls the pumping device to transport the raw acid through the pipeline assembly 4 to the inlet 11. The raw acid enters the primary distribution chamber 211 in the distribution beam 21 from the inlet 11. When the raw acid accumulates in the primary distribution chamber 211 to the height of the distribution port 212, it begins to fall from the distribution port 212 to the distribution bin 22 below. Several drains 221 on the distribution bin 22 evenly distribute the raw acid into several fine water columns. The water columns fall onto the packing and then fall into the reflux port 13 at the bottom of the purification tower 1. Finally, they enter the reboiler for heating through the reflux port 13.

[0061] During this period, the control system starts the reboiler, which heats the reserved raw acid inside, causing the nitric acid in the raw acid to absorb heat and form nitric acid gas. The nitric acid gas is transported to the inlet 12 through the pipeline assembly 4. After entering from the inlet 12, the nitric acid gas rises upward along the purification tower 1. During this process, the nitric acid gas continuously contacts the falling raw acid. The impurities contained in the nitric acid gas are mixed and carried away by the low-temperature liquid raw acid. At the same time, the nitric acid in the raw acid is converted into gas after absorbing heat and rises. This cycle continues, and the high-purity nitric acid gas rises step by step until it enters the condenser from the outlet 14.

[0062] The condenser cools the gaseous nitric acid to form clean liquid nitric acid. Then, the control system sends this portion of nitric acid to the bleaching and nanofilters for deep purification to obtain high-purity electronic-grade nitric acid.

[0063] When the raw acid falling through the distribution chamber 22 exhibits wall-attachment, the attached liquid will fall along the inner wall of the purification tower 1. When it falls to the collection ring 24, the collection port 241 of the collection ring 24 blocks the falling path and guides the attached liquid into the collection chamber 242. As the attached liquid converges, under the action of buoyancy, the float head 263 drives the float detector 26 to float upward. At this time, the falling port 243, which was blocked by the float head 263, opens, and the attached liquid falls along the cone rod 264 into the secondary distribution chamber 245, and flows out evenly from several distribution troughs 244. The guide head 247 guides the outflowing attached liquid at an angle, so that the attached liquid is away from the tower wall and flows out at an angle, avoiding secondary wall-attachment and achieving the primary anti-wall-attachment effect.

[0064] When the wall-mounted liquid exceeds the critical level, the liquid level in the concentrating ring 24 continues to rise, causing the float 263 to rise to the height of the connecting rod 261 under the action of buoyancy. The flexible contact 266 on the float 263 contacts and squeezes the protrusion 262 on the connecting rod 261. After being pressed, the flexible contact 266 drives the pressure head 269 to squeeze the piezoelectric body 268 downward. After being pressed, the piezoelectric body 268 generates an electrical signal. After receiving the electrical signal, the control system opens the telescopic rod 254. The output shaft of the telescopic rod 254 drives the base plate 253 to descend. The base plate 253 drives the elastic bladder 252 to open. The overflow chamber inside the elastic bladder 252 expands rapidly, and the overflowing wall-mounted liquid flows into the overflow chamber from the overflow port 246.

[0065] Simultaneously, the control system reduces the conveying speed of the raw acid, thereby reducing the flow rate of the liquid distribution chamber 22 and decreasing the continuous increase of the wall-attached liquid. When the wall-attached liquid gradually decreases to below the critical value, the float detector 26 descends, disconnecting from the connecting rod 261, and the electrical signal disappears. Then, the control system controls the output shaft of the telescopic rod 254 to slowly extend. The output shaft of the telescopic rod 254 drives the base plate 253 to press upwards against the elastic bladder 252. The elastic bladder 252 contracts under pressure, and the overflow liquid in the overflow chamber is reversed and squeezed from the overflow port 246 into the secondary liquid distribution chamber 245, and then discharged by the secondary liquid distribution system, thus achieving a two-stage anti-wall-attached effect. If the electrical signal persists and the wall-attached liquid cannot be eliminated, the control system sends an alarm signal to the operator, who then stops the machine for maintenance.

[0066] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A fully automated production line for preparing high-purity electronic-grade nitric acid, characterized in that: The production line includes a purification tower (1), a liquid distribution anti-slip device (2), a control system and a pipeline assembly (4). The purification tower (1) is connected to a reboiler and a condenser through the pipeline assembly (4). The liquid distribution anti-snagging device (2) includes a liquid distribution beam (21) and a flow-gathering ring (24). The liquid distribution beam (21) is installed inside the purification tower (1). Several liquid distribution chambers (22) are installed at the bottom of the liquid distribution beam (21). Demisting rings (23) are installed between the liquid distribution chambers (22). The flow-gathering ring (24) is installed on the outer wall of the purification tower (1). The flow-gathering ring (24) has an inlet and outlet. Several float detectors (26) are movably installed inside the flow-gathering ring (24). Several anti-overflow and backflow mechanisms (25) are installed on the outer wall of the purification tower (1). The anti-overflow and backflow mechanisms (25) are connected to the flow-gathering ring (24). The flow-gathering ring (24) is located below the liquid distribution chambers (22). The anti-overflow and backflow mechanisms (25) and the float detectors (26) are both electrically connected to the control system. The inlet and outlet include a collection port (241) and several liquid distribution troughs (244). The flow-gathering ring (24) is provided with a flow-gathering cavity (242), and a secondary liquid distribution cavity (245) is provided below the bottom end of the flow-gathering cavity (242). The bottom end of the flow-gathering cavity (242) is provided with several drop ports (243). The float detector (26) is movably installed on the drop ports (243). The bottom end of the flow-gathering ring (24) is provided with a secondary liquid distribution cavity (245), and the secondary liquid distribution cavity (245) is connected to the flow-gathering cavity (242) through the drop ports (243). The liquid distribution chamber (245) is provided with an overflow port (246) at the top. The secondary liquid distribution chamber (245) is connected to the anti-overflow and backflow mechanism (25) through the overflow port (246). Several liquid distribution inclined troughs (244) are provided on the side of the secondary liquid distribution chamber (245) away from the anti-overflow and backflow mechanism (25). The liquid distribution inclined troughs (244) are provided with guide heads (247). The collection port (241) blocks the falling path of the wall-mounted liquid and guides the wall-scraping liquid into the flow-gathering chamber (242). The anti-overflow and backflow mechanism (25) includes an end shell (251) and a connecting block (255). An elastic bladder (252) is installed at the bottom of the end shell (251), and a base plate (253) is installed at the bottom of the elastic bladder (252). The elastic bladder (252), the end shell (251) and the base plate (253) form an overflow cavity. The overflow cavity is connected to the secondary liquid distribution cavity (245) through an overflow port (246). The connecting block (255) is installed on the outer wall of the purification tower (1). A telescopic rod (254) is installed on the connecting block (255), and the output shaft of the telescopic rod (254) is connected to the base plate (253).

2. The fully automated production line for preparing high-purity electronic-grade nitric acid according to claim 1, characterized in that: The float detector (26) includes a cone rod (264) and a connecting rod (261). The connecting rod (261) is mounted on the current-collecting ring (24). The connecting rod (261) has a protrusion (262). The cone rod (264) is movably mounted on the drop port (243). A limit ring (265) is installed at the bottom end of the cone rod (264). A float head (263) is installed at the top end of the cone rod (264). A detection element is provided inside the float head (263). The cone rod (264) adopts an inverted cone design.

3. The fully automated production line for preparing high-purity electronic-grade nitric acid according to claim 2, characterized in that: The detection element includes a flexible contact (266) and a protective diaphragm (267). The flexible contact (266) is installed at the top of the float (263), and a pressure head (269) is provided at the bottom of the flexible contact (266). The protective diaphragms (267) are symmetrically installed inside the float (263), and a piezoelectric element (268) is installed between the protective diaphragms (267).

4. The fully automated production line for preparing high-purity electronic-grade nitric acid according to claim 2, characterized in that: The demisting ring (23) includes several connectors (235), which are installed between the liquid distribution chambers (22). Several vertical rings (231) are installed on the connectors (235). An upper ring plate (232) is installed on one side of the vertical ring (231), and a lower ring plate (233) is installed on the other side of the vertical ring (231). An S-shaped demisting channel (234) is formed between adjacent upper ring plates (232) and lower ring plates (233).

5. The fully automated production line for preparing high-purity electronic-grade nitric acid according to claim 1, characterized in that: The purification tower (1) is provided with an outlet (14) at the top, and the outlet (14) is connected to the condenser through a pipeline assembly (4). The purification tower (1) is provided with a reflux port (13) at the bottom, and the reflux port (13) is connected to the reboiler through a pipeline assembly (4). The purification tower (1) is provided with an inlet (12), and the inlet (12) is connected to the reboiler through a pipeline assembly (4). The purification tower (1) is provided with a liquid inlet (11), one end of which is connected to a feed box (3) through a pipeline assembly (4), and the other end of which is connected to a liquid separator beam (21).

6. The fully automated production line for preparing high-purity electronic-grade nitric acid according to claim 5, characterized in that: The liquid distribution beam (21) is provided with a primary liquid distribution chamber (211), which is connected to the liquid inlet (11). Several liquid distribution ports (212) are provided on both sides of the primary liquid distribution chamber (211), and the liquid distribution ports (212) are located above the liquid distribution chamber (22).

7. The fully automated production line for preparing high-purity electronic-grade nitric acid according to claim 1, characterized in that: The liquid distribution chamber (22) has several leaks (221) at its bottom.

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