A production system for preparing hydrogen fluoride from ammonium bifluoride

Abstract

The utility model discloses a production system for preparing hydrogen fluoride from ammonium bifluoride, belonging to the technical field of hydrogen fluoride production. The production system comprises a high-position raw material storage tank, a raw material pretreater, a decomposition reactor, an absorption separator and a liquefaction separator. A hydrogen fluoride storage tank is arranged at the rear side of the working position of the liquefaction separator. A continuous passage for hydrogen fluoride preparation and purification is formed between the high-position raw material storage tank, the raw material pretreater, the decomposition reactor, the absorption separator, the liquefaction separator and the hydrogen fluoride storage tank. On the one hand, the production system can be well matched with the hydrogen fluoride production process, ensuring that the production process is simple. On the other hand, the production system can ensure that the reaction in the production of hydrogen fluoride is controllable, safe, green, environmentally friendly and the like, and high-purity (>=98%) hydrogen fluoride is obtained to meet the actual demand.

Description

Technical Field

[0001] This utility model relates to a hydrogen fluoride production system, specifically a production system for preparing hydrogen fluoride from ammonium bifluoride, and belongs to the field of hydrogen fluoride production technology. Background Technology

[0002] Hydrogen fluoride (HF) is a colorless gas or liquid with a pungent odor. It is highly corrosive and toxic, reacting with materials such as glass and silicates. Its aqueous solution (hydrofluoric acid) plays an irreplaceable role in the electronics industry, refrigerants, pharmaceuticals, and the synthesis of new materials. For example, in semiconductor manufacturing, high-purity electronic-grade hydrogen fluoride is used in wafer cleaning and etching processes; in the new energy field, hydrogen fluoride is an important raw material for the preparation of lithium hexafluorophosphate (a key component of lithium-ion battery electrolytes). With the rapid development of the global semiconductor, photovoltaic, and new energy vehicle industries, the demand for electronic-grade and high-purity hydrogen fluoride continues to grow, and the future market potential is expected to be enormous.

[0003] However, the production, storage, and use of hydrogen fluoride face severe challenges. Due to its highly corrosive nature, it places extremely high demands on equipment materials, and traditional preparation processes often generate large amounts of pollutants (such as fluorogypsum and fluoride-containing wastewater), resulting in significant environmental pressure. Furthermore, current hydrogen fluoride synthesis technologies largely rely on the fluorite-sulfuric acid route, which consumes large amounts of resources and produces high carbon emissions, necessitating safer and more environmentally friendly alternative processes.

[0004] Currently, the main industrial production methods for hydrogen fluoride include: I. Fluorite-Sulfuric Acid Process: Fluorite (CaF2) reacts with concentrated sulfuric acid to produce hydrogen fluoride, with fluorogypsum as a byproduct. This technology is mature and has a high yield, but it suffers from problems such as high raw material consumption, difficult-to-treat byproducts, and severe equipment corrosion. II. Fluorosilicic acid method: Hydrogen fluoride is produced by decomposing fluorosilicic acid (H2SiF6) produced as a byproduct of phosphate fertilizer production. This method can reduce dependence on fluorite, but the process is complex, energy-intensive, and requires the treatment of a large amount of dilute sulfuric acid byproducts. III. Fluorine-containing waste recovery method: Ammonium hydrogen fluoride (NH4HF2) is recovered from nitrogen trifluoride waste electrolyte and then decomposed into hydrogen fluoride. Although this method conforms to the concept of circular economy, existing processes have problems such as low recovery efficiency and insufficient product purity.

[0005] Therefore, the above methods generally have the following drawbacks: poor safety, as high temperature and high pressure reaction conditions can easily lead to the risk of hydrogen fluoride leakage; high environmental pressure, as the treatment cost of by-products (such as fluorogypsum and fluoride-containing wastewater) is high and can easily cause environmental pollution; and limited purity, as traditional processes are difficult to stably prepare high-purity (≥98%) hydrogen fluoride, which restricts its application in high-end fields.

[0006] Although the prior art CN217988383U discloses a "system for the safe production of anhydrous hydrogen fluoride," it mainly eliminates the water cooler and replaces the heating source of the reboiler with hydrogen fluoride gas at 55-75℃. This means that the anhydrous hydrogen fluoride production system does not require the construction and installation of a circulating water system and a boiler system, achieving the goals of saving investment, saving energy, and eliminating the risk of major safety accidents caused by system leaks. The prior art CN113800470A provides an "apparatus and process for preparing hydrofluoric acid by ammoniation," which utilizes fluorosilicic acid solution, a byproduct of fluorine-containing resource waste phosphate fertilizer, to prepare hydrogen fluoride gas using an ammoniation method. However, the above-mentioned prior art are all based on the fluorosilicic acid method or the fluorite-sulfuric acid method to produce hydrogen fluoride, involving relatively complex process flows, and are suitable for large-scale, industrial production. Summary of the Invention

[0007] To address the problems of existing technologies that use fluorosilicic acid or fluorite resources as the source, which cannot meet the demand for high-purity hydrogen fluoride in small-scale or irregular situations within a limited space (e.g., poor reaction controllability, inability to start and stop quickly, poor safety and environmental protection, etc.) and have complex process flows, a production system for preparing hydrogen fluoride using ammonium bifluoride is proposed. In this technical solution, an elevated raw material storage tank, a raw material pre-processor, a decomposition reactor, an absorption separator, and a liquefaction separator are used to decompose ammonium bifluoride as a raw material under a nitrogen atmosphere and at a certain temperature (125–250°C) to generate a mixed gas containing hydrogen fluoride. This mixed gas is then absorbed by an active substance to form a complex (complex salt), thereby separating the hydrogen fluoride gas from other gases. Subsequently, the complex is cracked under a nitrogen atmosphere and at a certain temperature (150–200°C) to generate hydrogen fluoride gas, displacing the active substance. Finally, purification is performed to obtain hydrogen fluoride gas with a purity ≥98%. This production system achieves a simple, controllable, rapid start-up and shutdown, safe, and environmentally friendly recyclable hydrogen fluoride production process.

[0008] To achieve the above technical objectives, the following technical solution is proposed: The objective of this technical solution is to provide: a production system for preparing hydrogen fluoride from ammonium bifluoride, comprising a high-level raw material storage tank for storing ammonium bifluoride particles, a raw material preprocessor for drying the ammonium bifluoride particles, a decomposition reactor for decomposing the ammonium bifluoride, an absorption separator for absorbing and cracking the generated hydrogen fluoride, and a liquefaction separator for purifying the hydrogen fluoride, wherein... High-level raw material storage tank: The outer side is equipped with a jacket I, and the high-level raw material storage tank is connected to a nitrogen inlet pipe I; the high-level raw material storage tank is located in front of the station of the raw material preprocessor, and the discharge port on the high-level raw material storage tank is connected to the inlet on the raw material preprocessor. Raw material preprocessor: It is equipped with a jacket II on the outside, and the raw material preprocessor is connected to a nitrogen inlet pipe II and a dry air inlet pipe. The discharge port of the raw material preprocessor is connected to the feed port of the decomposition reactor. Decomposition reactor: It is equipped with a jacket III on the outside and is connected to a nitrogen inlet pipe III; the decomposition reactor is located behind the station of the raw material preprocessor and the discharge port of the decomposition reactor is connected to the inlet of the absorption separator. Absorption separator: It is equipped with a jacket IV on the outside, and the absorption separator is connected to a nitrogen inlet pipe IV and an active material inlet pipe; the absorption separator is located on the rear side of the decomposition reactor, and the discharge port of the absorption separator is connected to the feed port of the liquefaction separator. Liquefaction separator: It is connected to nitrogen inlet pipe V. The liquefaction separator is located behind the station of the absorption separator. The outlet of the liquefaction separator is connected to a hydrogen fluoride storage tank. The hydrogen fluoride storage tank is connected to nitrogen inlet pipe VI. A continuous pathway for hydrogen fluoride preparation and purification is formed between the high-level raw material storage tank, the raw material preprocessor, the decomposition reactor, the absorption separator, the liquefaction separator, and the hydrogen fluoride storage tank.

[0009] Furthermore, the outlet of the absorption separator is connected to the ammonia adsorption tower through a tail gas delivery pipe to remove ammonia from the tail gas discharged from the absorption separator; the ammonia adsorption tower is equipped with a water spraying mechanism, and the ammonia water formed can be recycled and reused in the future. The outlet of the ammonia adsorption tower is connected to an adsorption column, which contains activated carbon or molecular sieves to adsorb ammonia (small amount), nitrogen and hydrogen fluoride (trace amount) in the tail gas after ammonia removal, and then discharge it to the outside.

[0010] Furthermore, a heat exchanger I is provided between the decomposition reactor and the absorption separator to cool down the high-temperature mixed gas before it is introduced into the absorption separator, which facilitates material transportation and reduces damage to the equipment.

[0011] Furthermore, a heat exchanger II is provided between the absorption separator and the liquefaction separator, which cools down the higher-temperature gaseous product - crude hydrogen fluoride gas - before it is introduced into the liquefaction separator, which facilitates material transportation and reduces damage to the equipment.

[0012] Furthermore, in the decomposition reactor, jacket Ⅲ is connected to a temperature regulating medium inlet pipe, the temperature regulating medium inlet pipe is equipped with a temperature regulating medium control valve, nitrogen inlet pipe Ⅲ is equipped with a nitrogen control valve and pressure sensor Ⅰ, and the decomposition reactor is equipped with a temperature sensor. The outlet of the absorber is equipped with a pressure sensor II and an online detector for detecting the concentration of hydrogen fluoride; A mixed gas inlet pipe is provided between the decomposition reactor and the absorption separator, and a mixed gas control valve is provided on the mixed gas inlet pipe; The online monitoring instrument, temperature sensor, and temperature control medium regulating valve are interlocked via electrical signals. Pressure sensor II, pressure sensor I, and nitrogen control valve are interlocked via electrical signals; The online detector is interlocked with the gas mixture control valve via an electrical signal.

[0013] In this technical solution, sensors (such as temperature sensors, pressure sensors), control valves, flow meters, etc., are installed at appropriate locations according to actual needs.

[0014] The positional relationships such as "behind the workstation," "between," "above," "front of the workstation," and "outer side" involved in this technical solution are defined according to the actual usage conditions and are conventional terms in this technical field, as well as conventional terms used by those skilled in the art in actual use.

[0015] In the description of this technical solution, it should be noted that, unless otherwise explicitly specified and limited, the terms "setting" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0016] The beneficial technical effects of adopting this technical solution are as follows: I. This utility model, through the configuration of a high-level raw material storage tank, a raw material pre-processor, a decomposition reactor, an absorption separator, a liquefaction separator, and a hydrogen fluoride storage tank, forms a continuous pathway for the preparation and purification of hydrogen fluoride. Firstly, this production system can be well integrated with the hydrogen fluoride production process, ensuring a simple production flow (using ammonium bifluoride granules as raw material, through pretreatment-decomposition-absorption-pyrolysis-purification, to obtain hydrogen fluoride). Secondly, this production system can ensure that the reaction in the production of hydrogen fluoride is controllable (by setting up decomposition reactors, absorption separators, etc., the decomposition, absorption and pyrolysis purification are designed in stages, and combined with nitrogen protection, step temperature control and adsorption and separation technology of active materials (such as potassium / sodium hydrogen fluoride), the production process is highly controllable), safe, green (active materials can be recycled and reused at low cost), and environmentally friendly (ammonia is adsorbed and then discharged, of which the adsorbed ammonia can be reused), and obtain high-purity (≥98%) hydrogen fluoride; Furthermore, this production system is particularly suitable for small-scale or irregular high-purity hydrogen fluoride demand in confined spaces (e.g., strong reaction controllability, rapid start-up and shutdown, good safety and environmental protection, etc.). Second, in this utility model, the dynamic balance between decomposition and absorption is ensured through the synergistic effect of the temperature regulating medium control valve, nitrogen control valve, pressure sensor I, temperature sensor, pressure sensor II, online detector, and mixed gas control valve, so as to achieve controllable reaction and rapid start-up and shutdown, while improving the stability and safety of hydrogen fluoride production process. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the working principle of the production system in this utility model; Figure 2 This is a block diagram of the equipment structure of the production system in this utility model; In the diagram, 1. High-level raw material storage tank, 2. Raw material pre-processor, 3. Decomposition reactor, 4. Absorption separator, 5. Liquefaction separator, 6. Hydrogen fluoride storage tank, 7. Dry air inlet pipe, 8. Nitrogen inlet pipe I, 10. Active substance inlet pipe, 11. Nitrogen inlet pipe II, 13. Tail gas conveying pipe, 14. Ammonia adsorption tower, 15. Heat exchanger I, 16. Heat exchanger II, 17. Adsorption column, 18. Nitrogen inlet pipe III, 19. Nitrogen inlet pipe IV, 20. Nitrogen inlet pipe V, 21. Nitrogen inlet pipe VI; 22. Temperature regulating medium inlet pipe; 23. Temperature regulating medium control valve; 24. Nitrogen control valve; 26. Pressure sensor I; 27. Temperature sensor; 28. Pressure sensor II; 29. ​​Online detector; 30. Mixed gas inlet pipe; 31. Mixed gas control valve. Detailed Implementation

[0018] The technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0019] Example 1 This embodiment provides a production system for preparing hydrogen fluoride from ammonium bifluoride, such as: Figure 1-2 As shown, the system includes a high-level raw material storage tank 1 for storing ammonium bifluoride granules, a raw material pre-processor 2 for drying the ammonium bifluoride granules, a decomposition reactor 3 for decomposing the ammonium bifluoride, an absorption separator 4 for absorbing and cracking the generated hydrogen fluoride, and a liquefaction separator 5 for purifying the hydrogen fluoride. The high-level raw material storage tank 1 is connected to a nitrogen inlet pipe I8. The high-level raw material storage tank 1 is located in front of the work station of the raw material preprocessor 2. The discharge port of the high-level raw material storage tank 1 is connected to the inlet of the raw material preprocessor 2. The raw material preprocessor 2 is connected to a nitrogen inlet pipe II11 and a dry air inlet pipe 7. The discharge port of the raw material preprocessor 2 is connected to the feed port of the decomposition reactor 3. The decomposition reactor 3 is connected to a nitrogen inlet pipe Ⅲ18. The decomposition reactor 3 is located behind the work station of the raw material preprocessor 2. The discharge port of the decomposition reactor 3 is connected to the inlet of the absorption separator 4. The absorption separator 4 is connected to a nitrogen inlet pipe IV19 and an active material inlet pipe 10. The absorption separator 4 is located behind the station of the decomposition reactor 3. The discharge port of the absorption separator 4 is connected to the inlet of the liquefaction separator 5. The liquefaction separator 5 is connected to a nitrogen inlet pipe V20. The liquefaction separator 5 is located behind the station of the absorption separator 4. The outlet of the liquefaction separator 5 is connected to a hydrogen fluoride storage tank 6, and the hydrogen fluoride storage tank 6 is connected to a nitrogen inlet pipe VI21. A continuous pathway for hydrogen fluoride preparation and purification is formed between the high-level raw material storage tank 1, the raw material pre-processor 2, the decomposition reactor 3, the absorption separator 4, the liquefaction separator 5, and the hydrogen fluoride storage tank 6.

[0020] This production system can be well integrated with the production process, providing a prerequisite guarantee for the continuity and stability of the production process. Ultimately, it ensures the safety (dynamic balance between absorption and cracking) and environmental friendliness of the hydrogen fluoride process (the active materials - potassium / sodium hydrogen fluoride - are recyclable and low in cost).

[0021] Example 2 Based on Example 1, this example further specifies the following to maintain the temperature inside the high-level raw material storage tank 1, the raw material pre-processor 2, the decomposition reactor 3, and the absorption separator 4: The high-level raw material storage tank 1 is equipped with a jacket I on the outside, the raw material preprocessor 2 is equipped with a jacket II on the outside, the decomposition reactor 3 is equipped with a jacket III on the outside, and the absorption separator 4 is equipped with a jacket IV on the outside.

[0022] Example 3 Based on Examples 1-2, this example further specifies the following to ensure a dynamic balance between decomposition and absorption: Jacket Ⅲ is connected to temperature regulating medium inlet pipe 22, temperature regulating medium inlet pipe 22 is equipped with temperature regulating medium control valve 23, nitrogen inlet pipe Ⅲ 18 is equipped with nitrogen control valve 24 and pressure sensor Ⅰ 26, and decomposition reactor 3 is equipped with temperature sensor 27. The outlet of the absorber separator 4 is equipped with a pressure sensor II 28 and an online detector 29 for detecting the concentration of hydrogen fluoride; A mixed gas inlet pipe 30 is provided between the decomposition reactor 3 and the absorption separator 4, and a mixed gas control valve 31 is provided on the mixed gas inlet pipe 30. The online detector 29, temperature sensor 27, and temperature regulating medium control valve 23 are interlocked via electrical signals. For example, if the HF concentration detected by the online detector 29 is greater than 2% at the outlet of the absorber separator 4, the decomposition temperature in the decomposition reactor 3 is reduced by adjusting the opening of the temperature regulating medium control valve 23. Pressure sensor II 28, pressure sensor I 26, and nitrogen control valve 24 are interlocked via electrical signals. For example, when the pressure at the outlet of the absorber separator 4 is too high, the flow rate and partial pressure of N2 in the decomposition reactor 3 are reduced. The online detector 29 is interlocked with the mixed gas control valve 31 via an electrical signal. For example, after absorption is completed (i.e., the hydrogen fluoride gas content at the outlet of the absorber separator 4 is ≥0.1%, which can be monitored by the online detector 29), the mixed gas inlet pipe 30 containing nitrogen, hydrogen fluoride, and ammonia, which is connected to the absorber separator 4, is closed.

[0023] Ultimately, a dynamic balance is achieved between decomposition and absorption, preventing excessive pressure.

[0024] Example 4 Based on Examples 1-3, this example makes the following improvements to further enhance the continuity and stability of the absorption reaction and pyrolysis separation within the absorber separator 4, as well as to improve environmental friendliness: The outlet of the absorber 4 is connected to the ammonia adsorption tower 14 through the tail gas delivery pipe 13 to remove ammonia from the tail gas discharged from the absorber 4; the ammonia adsorption tower 14 is equipped with a water spraying mechanism, and the ammonia water formed can be recycled and reused in the future. An adsorption column 17 is connected to the outlet of the ammonia adsorption tower 14. The adsorption column 17 is equipped with activated carbon or molecular sieve to adsorb ammonia (small amount), nitrogen and hydrogen fluoride (trace amount) in the tail gas after ammonia removal, and then discharge it to the outside.

[0025] Example 5 Based on Examples 1-4, the following improvements are made to further facilitate material conveying and to enhance safety and equipment lifespan: A heat exchanger I15 is installed between the decomposition reactor 3 and the absorption separator 4. It cools down the high-temperature mixed gas before it is introduced into the absorption separator 4, which facilitates material transportation and reduces damage to the equipment.

[0026] A heat exchanger II16 is installed between the absorption separator 4 and the liquefaction separator 5. It cools down the high-temperature gaseous product - crude hydrogen fluoride gas - before it is introduced into the liquefaction separator 5, which facilitates material transportation and reduces damage to the equipment.

[0027] The hydrogen fluoride production system is characterized in that heat exchanger I15 is a tubular heat exchanger or a plate heat exchanger, and heat exchanger II16 is a tubular heat exchanger or a plate heat exchanger.

[0028] Example 6 Based on Examples 1-5, in order to better implement the system and better integrate it with the production process, suitable high-level raw material storage tank 1, raw material pre-processor 2, decomposition reactor 3, absorption separator 4, liquefaction separator 5, and hydrogen fluoride storage tank 6 are selected, or corresponding improvements are made, as follows: High-level raw material storage tank 1: A vertical steel cylindrical tank with jacketed heat exchange. The heat exchange medium inside the jacket is demineralized water. The shell material is carbon steel and the inner lining is corrosion-resistant polymer. Temperature detection points (temperature detector I) and pressure detection points (pressure detector I) are installed inside the cavity to monitor the temperature and pressure inside the high-level raw material storage tank 1. When the weather is too hot, ammonium bifluoride absorbs heat and the temperature approaches 70°C. Raw material preprocessor 2: A drum dryer is used, with all parts in contact with the material lined with corrosion-resistant polymer. Temperature detection points (temperature detector II) and pressure detection points (pressure detector II) are installed inside the dryer cavity. Decomposition Reactor 3: This is a kettle-type structure, constructed entirely of carbon steel or stainless steel, lined with a corrosion-resistant polymer. The kettle lid and surrounding area are made of Hastelloy alloy. The lid is equipped with a feed inlet, a gas phase outlet, a temperature detection conduit (temperature detector III), a pressure detection conduit (pressure detector III), and an analytical sampling port. Heating is achieved via thermal oil, with a heating temperature not exceeding 300℃. Two temperature measurement points are located inside the kettle: the bottom material temperature measurement point is 5–10 cm from the bottom and 5–10 cm from the nearest kettle wall; the upper gas phase material temperature measurement point is 2–8 cm from the kettle lid. The sleeves around both temperature measurement points are made of Hastelloy alloy coated with a corrosion-resistant polymer. Absorption Separator 4: This is a kettle-type structure, constructed entirely of carbon steel or stainless steel, lined with a corrosion-resistant polymer. The kettle lid and surrounding area are made of Hastelloy alloy. The lid is equipped with a feed inlet, a gas phase outlet, a temperature detection conduit (temperature detector IV), a pressure detection conduit (pressure detector IV), and an analytical sampling port. Heating is via thermal oil, with a heating temperature of 100–130℃. Two temperature measuring points are located inside the kettle: the upper gas phase measuring point is 5–10 cm above the liquid surface, and the bottom measuring point is 5–10 cm from the bottom of the kettle (the composite salt is molten at around 100℃; it is solid at room temperature). The sleeves for both measuring points are made of Hastelloy alloy coated with a corrosion-resistant polymer.

[0029] Liquefaction separator 5: Employs a conventional, corrosion-resistant gas compressor; Hydrogen fluoride storage tank 6: A carbon steel tank lined with corrosion-resistant polymer; Heat exchangers I15 and II16: Both are tubular or plate heat exchangers, using low-temperature circulating water as the cooling medium. Ammonia adsorption tower 14: It is a vertical tank made of carbon steel, and demineralized water is used as the ammonia absorbent inside.

[0030] The corrosion-resistant polymer is modified polypropylene, polytetrafluoroethylene, polyaryletherketone, or polyimide. Modified polypropylene is preferred when the operating temperature is not higher than 100℃; polytetrafluoroethylene or polyaryletherketone is preferred when the operating temperature is 100–200℃; and polyimide is preferred when the operating temperature is 200–300℃.

[0031] Example 7 Based on Examples 1-6, this example provides: a production process for preparing hydrogen fluoride from ammonium bifluoride, comprising the following steps: S1 Pretreatment: The raw material ammonium bifluoride particles in the high-level raw material storage tank 1 are added to the raw material pretreatment unit 2. After drying and dehydration, dry ammonium bifluoride particles are obtained. If the raw material is not dehydrated, the water in the raw material will react with the HF generated later to form hydrofluoric acid. Hydrofluoric acid is highly corrosive and will have a certain impact on the equipment and subsequent operations. S2 decomposition: The dried ammonium bifluoride particles obtained in step S1 are introduced into the decomposition reactor 3. The decomposition reactor 3 is controlled to be in a nitrogen atmosphere and the decomposition temperature is 125-250℃ to obtain a mixed gas containing nitrogen (as a balance gas), hydrogen fluoride and ammonia (small amount). The reaction formulas involved include: NH4HF2→NH4F+HF(Ⅰ; NH4HF2→2HF+NH3(Ⅱ; NH4F →HF + NH3(III); S3 Absorption: Heat exchanger I15 is used to cool the mixed gas containing hydrogen fluoride, ammonia, and nitrogen to 90-120°C, and then it is introduced into the absorption separator 4. In the absorption separator 4, at a temperature of 100-130°C, the hydrogen fluoride in the mixed gas is absorbed by the active material in the absorption separator 4 and forms a complex (complex salt). The ammonia and nitrogen in the mixed gas are not absorbed and form tail gas. At this time, the tail gas contains ammonia, nitrogen, and trace amounts of unabsorbed hydrogen fluoride. The tail gas containing ammonia, nitrogen, and hydrogen fluoride is sequentially passed through an ammonia adsorption tower 14 and an adsorption column 17 (containing activated carbon or molecular sieves). The ammonia adsorption tower 14 absorbs and removes the ammonia from the tail gas. The tail gas is then further treated by adsorption in the adsorption column 17 (adsorbing a small amount of ammonia and trace amounts of hydrogen fluoride). Finally, the tail gas is sent to the exhaust pipe for external discharge. At this point, the tail gas mainly contains nitrogen, as well as trace amounts of ammonia and hydrogen fluoride (concentration ≤0.09 mg / m³), which complies with the "Air Pollutant Emission Standard". Among them, the active substance in the absorber separator 4 is potassium hydrogen fluoride, sodium hydrogen fluoride, potassium fluoride or sodium fluoride; with potassium hydrogen fluoride, the reaction involved is: KHF2+(1~3)HF→ KF•(2~4)HF; Taking potassium fluoride as an example, the reaction involved is: KF + HF → KHF2; In this technical solution, the active material is limited to "potassium hydrogen fluoride, sodium hydrogen fluoride, potassium fluoride or sodium fluoride", which effectively avoids the use of active materials with high decomposition temperature, resulting in high energy consumption and uneconomicalness. After absorption is complete (i.e., the hydrogen fluoride gas content at the outlet of the absorber separator 4 is ≥0.1%, which can be monitored using a gas concentration detector), close the inlet pipe of the mixed gas containing nitrogen, hydrogen fluoride and ammonia connected to the absorber separator 4 (one end of the inlet pipe is connected to the decomposition reactor 3, and the other end is connected to the absorber separator 4); S4 pyrolysis: After the active material in the absorber separator 4 is absorbed to the point of hydrogen fluoride saturation (an online detector 29 for detecting hydrogen fluoride concentration can be installed at the outlet of the absorber separator 4 to monitor whether the hydrogen fluoride in the absorber separator 4 is saturated. If the absorption is saturated, the hydrogen fluoride gas content at the outlet of the absorber separator 4 is ≥0.1%; if the absorption is not saturated, the hydrogen fluoride gas content at the outlet of the absorber separator 4 is <0.1%), nitrogen gas is introduced into the absorber separator 4 to purge away the remaining fluorine-containing gas; then, the temperature is raised to 150-200℃, the complex is pyrolyzed, forming solid and gaseous products. The solid product is the active material (potassium hydrogen fluoride, sodium hydrogen fluoride, potassium fluoride or sodium fluoride), and the gaseous product is crude hydrogen fluoride gas (mainly hydrogen fluoride, and containing a small amount of nitrogen). S5 Purification: Heat exchanger II16 is used to cool the obtained crude hydrogen fluoride gas to room temperature (15-30℃), and then it is introduced into liquefaction separator 5 to compress the obtained crude hydrogen fluoride gas, separate non-condensable gas, and obtain hydrogen fluoride gas with a volume concentration ≥98%, which is then introduced into hydrogen fluoride storage tank 6 for storage and standby. For the liquefaction separator 5, a conventional, corrosion-resistant gas compressor is generally used. During the compression process, the nitrogen in the crude hydrogen fluoride gas does not liquefy, while the hydrogen fluoride liquefies, thus achieving the separation of hydrogen fluoride and nitrogen and ensuring the purification of the hydrogen fluoride gas.

[0032] In the preprocessing step S1: The temperature of the circulating water inside the jacket of the high-level raw material storage tank 1 is controlled at 10-35℃. The volume of material inside the high-level raw material storage tank 1 does not exceed 70% of its capacity. The upper part of the high-level raw material storage tank 1 is sealed with nitrogen, with a nitrogen purity of >99.9% and a nitrogen sealing pressure of 0.3-0.6MPa. The raw material pre-processor 2 uses dry air with a dew point < -40℃ and a temperature below 35℃ to dehydrate the raw materials, with a batch processing time of 1 to 4 hours. In step S2 decomposition: Before the decomposition reaction begins, nitrogen gas with a purity of 99.9% or higher is used to replace the gas in decomposition reactor 3 to ensure that the nitrogen content in decomposition reactor 3 is >99% and to maintain a slight positive pressure of 10-30 kPa. Then, a stepped temperature control mode is adopted: the temperature is increased from room temperature to 80℃ at a rate of 5–10℃ / min; then increased from 80℃ to the set temperature of 125–250℃ at a rate of 2–5℃ / min, and after being kept constant, the temperature is maintained for decomposition. The generation rate of the mixed gas is controlled by adjusting the decomposition temperature. Gradient temperature control allows observation of whether hydrogen fluoride is generated at the set decomposition starting point, thus determining whether the decomposition reactor 3 is functioning correctly. Without stepped temperature control, it would be difficult to determine whether the decomposition reactor 3 is functioning correctly, thereby compromising the sustainability and stability of the production process. During the decomposition reaction, the pressure inside the decomposition reactor 3 is maintained at 50–150 kPa. In step S3 absorption: The decomposed mixed gas is introduced into heat exchanger I15, and the outlet temperature of heat exchanger I15 is controlled to be <100℃. Before the absorption reaction begins, the gas inside the absorption separator 4 is replaced with nitrogen gas of 99.9% or higher to ensure that the nitrogen content inside the absorption separator 4 is >99% and to maintain a slight positive pressure of 10-30 kPa. The mixed gas inlet pipe connected to heat exchanger I15 is inserted to the bottom of the absorption separator 4; during the absorption reaction, the temperature inside the absorption separator 4 is maintained at 100-130℃, and the hydrogen fluoride content in the outlet of the absorption separator 4 is ensured to be <0.1% by controlling the inlet rate of the gas (the mixed gas generated in the self-decomposition reactor 3); among which, the amount of ammonium bifluoride used in a single batch, a, is linearly related to the amount of active material (sodium bifluoride / potassium bifluoride), b: a=3b; In step S4 pyrolysis: Before the pyrolysis reaction begins, the absorber separator 4 is purged with nitrogen of 99.9% or higher to ensure that the nitrogen content in the absorber separator 4 is >99% and to maintain a slight positive pressure of 10-30 kPa. Then, the temperature inside the absorber separator 4 is raised to 150-170℃ and held for 1-2 hours; the temperature is then raised to 180-200℃ and held for 1-4 hours to ensure that the decomposition rate of hydrogen fluoride adsorbed by the active material is ≥99%. In step S5 purification: The crude hydrogen fluoride gas formed is introduced into heat exchanger II16, and the outlet temperature of heat exchanger II16 is controlled to be <30℃. The temperature inside the hydrogen fluoride storage tank 6 is controlled at 10-18℃, and the hydrogen fluoride storage tank 6 is pressurized to 0.3-1.0MPa with nitrogen.

[0033] Example 8 Based on Examples 1-6, this example provides: a production process for preparing hydrogen fluoride from ammonium bifluoride, comprising: I. Selection of raw materials, gaseous medium, and active substances; and arrangement of equipment. 1. Raw material: Ammonium bifluoride (NH4HF2) granules, purity ≥99%; Gaseous medium: Nitrogen, purity > 99.9%; Active ingredient: A mixture of sodium hydrogen fluoride (NaHF2) and potassium hydrogen fluoride (KHF2) (mass ratio 1:1). 2. Equipment High-level raw material storage tank 1: carbon steel lined with polyaryletherketone, with a jacketed circulating water temperature of 20℃, and the tank is filled with material to 60% of its volume; Raw material preprocessor 2: Uses a drum dryer lined with corrosion-resistant polymer; Decomposition reactor 3: Carbon steel lined with polytetrafluoroethylene, heated by heat transfer oil in the jacket, with temperature measuring tubes inserted to 5cm from the bottom of the reactor and 2cm from the lid; Absorption Separator 4: Stainless steel lined with polyimide, mixed gas inlet pipe inserted at the bottom, with potassium hydrogen fluoride built in as the active material for absorption; Heat exchanger: Tubular heat exchanger, low-temperature circulating water inlet temperature 3℃; Ammonia adsorption tower 14: Carbon steel tank, used for adsorbing and recovering ammonia water. A multi-stage spray system is added to improve ammonia absorption efficiency. Liquefaction Separator 5: Three-stage compressor; Hydrogen fluoride storage tank 6: lined with polyimide.

[0034] II. Process Flow (1) Decomposition and absorption Ammonium bifluoride granules are introduced from the high-level raw material storage tank 1 into a drum dryer, where dry hot air with a dew point of -55℃ and a temperature of 28℃ is introduced for 1.5 hours to remove trace amounts of moisture. The pretreated ammonium bifluoride is then conveyed to the decomposition reactor 3 via a screw conveyor, where nitrogen gas (purity ≥ 99.9%) is introduced to replace the oxygen content to < 0.4%, maintaining a slight positive pressure of 15 kPa. Then, a stepped temperature control is used: the decomposition reactor 3 is heated from room temperature to 80℃ at a rate of 10℃ / min and held at that temperature for 1 hour; then heated to 170℃ at a rate of 5℃ / min and held at that temperature for 1 hour; finally, heated to 230℃ at a rate of 0.5℃ / min and held at that temperature for 2.5 hours, with the decomposition reaction pressure stabilizing at 80 kPa. The mixed gas produced by the decomposition reaction (containing HF, NH3, N2 and a small amount of ammonium fluoride) is cooled to 95°C by a tubular heat exchanger and enters the absorption separator 4. The absorption separator 4 is kept at 100°C, where the active material fully absorbs HF, and the HF content in the outlet gas is <0.03%. The tail gas is fed into an ammonia absorption tower, where a three-stage spray device is used to absorb NH3, resulting in ammonia water with a concentration of 30%. The remaining tail gas is discharged after the residual NH3 is removed by a zeolite-activated carbon adsorption column 17, and the residual NH3 content in the tail gas is <2 ppm, which meets environmental protection requirements. (2) Pyrolysis and purification After the sodium hydrogen fluoride in the absorber separator 4 is saturated, nitrogen gas (purity ≥ 99.9%) is introduced to replace the oxygen content until it is < 0.2%, maintaining a slight positive pressure of 10 kPa. Then, a stepped temperature control is used: the temperature is increased to 155℃ at a rate of 1℃ / min and held at that temperature for 3 hours; then the temperature is increased to 195℃ at a rate of 0.5℃ / min and held at that temperature for 3.5 hours, controlling the cracking rate to ≥ 99.9%. The HF gas produced by cracking is cooled by a tubular heat exchanger and then enters a three-stage compressor; the three-stage compressor is pressurized to 0.4 MPa to remove non-condensable gases, finally obtaining anhydrous hydrogen fluoride with a purity of 99.5%, which is stored in hydrogen fluoride storage tank 6 (temperature controlled at 10℃).

[0035] Under the above process conditions, after 300 consecutive batches of operation, the core equipment, including the raw material preprocessor 2, remained stable, and the inner lining polymer showed no signs of corrosion. Hydrogen fluoride gas product specifications: purity 99.5%, moisture content <0.01%.

[0036] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A production system for preparing hydrogen fluoride from ammonium bifluoride, characterized in that, The system includes a high-level raw material storage tank (1) for storing ammonium bifluoride granules, a raw material pre-processor (2) for drying the ammonium bifluoride granules, a decomposition reactor (3) for decomposing ammonium bifluoride, an absorption separator (4) for absorbing and cracking the generated hydrogen fluoride, and a liquefaction separator (5) for purifying the hydrogen fluoride. The high-level raw material storage tank (1) is connected to a nitrogen inlet pipe I (8). The high-level raw material storage tank (1) is located in front of the work station of the raw material preprocessor (2). The discharge port of the high-level raw material storage tank (1) is connected to the inlet of the raw material preprocessor (2). The raw material preprocessor (2) is connected to a nitrogen inlet pipe II (11) and a dry air inlet pipe (7), and the upper outlet of the raw material preprocessor (2) is connected to the upper inlet of the decomposition reactor (3); The decomposition reactor (3) is connected to a nitrogen inlet pipe III (18). The decomposition reactor (3) is located behind the work station of the raw material preprocessor (2). The discharge port of the decomposition reactor (3) is connected to the inlet of the absorption separator (4). The absorption separator (4) is connected to the nitrogen inlet pipe IV (19) and the active substance inlet pipe (10). The absorption separator (4) is located on the back side of the decomposition reactor (3). The discharge port of the absorption separator (4) is connected to the feed port of the liquefaction separator (5). The liquefaction separator (5) is connected to a nitrogen inlet pipe V (20). The liquefaction separator (5) is located behind the station of the absorption separator (4). The outlet of the liquefaction separator (5) is connected to a hydrogen fluoride storage tank (6). The hydrogen fluoride storage tank (6) is connected to a nitrogen inlet pipe VI (21). A continuous pathway for the preparation and purification of hydrogen fluoride is formed between the high-level raw material storage tank (1), the raw material pre-processor (2), the decomposition reactor (3), the absorption separator (4), the liquefaction separator (5), and the hydrogen fluoride storage tank (6).

2. The production system for preparing hydrogen fluoride from ammonium bifluoride according to claim 1, characterized in that, The high-level raw material storage tank (1) is provided with a jacket I on the outside, the raw material preprocessor (2) is provided with a jacket II on the outside, the decomposition reactor (3) is provided with a jacket III on the outside, and the absorption separator (4) is provided with a jacket IV on the outside.

3. The production system for preparing hydrogen fluoride from ammonium bifluoride according to claim 2, characterized in that, The jacket Ⅲ is connected to a temperature regulating medium inlet pipe (22), and a temperature regulating medium control valve (23) is provided on the temperature regulating medium inlet pipe (22). A nitrogen control valve (24) and a pressure sensor Ⅰ (26) are provided on the nitrogen inlet pipe Ⅲ (18). A temperature sensor (27) is provided on the decomposition reactor (3). Pressure sensor II (28) and an online detector (29) for detecting hydrogen fluoride concentration are provided at the outlet of the absorber separator (4). A mixed gas inlet pipe (30) is provided between the decomposition reactor (3) and the absorption separator (4), and a mixed gas control valve (31) is provided on the mixed gas inlet pipe (30). The online detector (29), temperature sensor (27) and temperature regulating medium control valve (23) are interlocked by electrical signals; Pressure sensor II (28), pressure sensor I (26), and nitrogen control valve (24) are interlocked by electrical signals; The online detector (29) and the mixed gas control valve (31) are interlocked by an electrical signal.

4. The production system for preparing hydrogen fluoride from ammonium bifluoride according to claim 1, characterized in that, The outlet of the absorber (4) is connected to the ammonia adsorption tower (14) through the tail gas delivery pipe (13). The ammonia adsorption tower (14) is equipped with a water spraying mechanism. The outlet of the ammonia adsorption tower (14) is connected to an adsorption column (17). The adsorption column (17) is equipped with activated carbon or molecular sieve.

5. The production system for preparing hydrogen fluoride from ammonium bifluoride according to any one of claims 1-4, characterized in that, A heat exchanger I (15) is provided between the decomposition reactor (3) and the absorption separator (4).

6. The production system for preparing hydrogen fluoride from ammonium bifluoride according to claim 5, characterized in that, A heat exchanger II (16) is provided between the absorption separator (4) and the liquefaction separator (5).

7. The production system for preparing hydrogen fluoride from ammonium bifluoride according to claim 6, characterized in that, The heat exchanger I (15) is a tubular heat exchanger or a plate heat exchanger, and the heat exchanger II (16) is a tubular heat exchanger or a plate heat exchanger.

8. The production system for preparing hydrogen fluoride from ammonium bifluoride according to claim 1, characterized in that, The raw material pre-processor (2) is a drum dryer.

9. The production system for preparing hydrogen fluoride from ammonium bifluoride according to claim 1, characterized in that, The decomposition reactor (3) is equipped with a bottom material temperature measuring point and an upper gas phase material temperature measuring point. The bottom material temperature measuring point is 5-10cm away from the bottom of the reactor and 5-10cm away from the nearest side of the reactor wall; the upper gas phase material temperature measuring point is 2-8cm away from the reactor cover.

10. The production system for preparing hydrogen fluoride from ammonium bifluoride according to claim 1, characterized in that, The liquefaction separator (5) is a gas compressor.

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