Production process and system for preparing hydrogen fluoride from ammonium bifluoride

Abstract

The invention discloses a production process and system for preparing hydrogen fluoride from ammonium bifluoride, and belongs to the technical field of hydrogen fluoride production. The production process comprises the steps of pretreatment, decomposition, absorption, cracking and purification. The system comprises a high-position raw material storage tank used for storing ammonium hydrogen fluoride particles, a raw material preprocessor used for drying the ammonium hydrogen fluoride particles, a decomposition reactor used for decomposing ammonium hydrogen fluoride, an absorption separator used for absorbing and cracking generated hydrogen fluoride, a liquefaction separator used for purifying hydrogen fluoride and a hydrogen fluoride storage tank. And a continuous passage for preparing and purifying hydrogen fluoride is formed among 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. In the preparation of hydrogen fluoride, the hydrogen fluoride process is safe, green and environment-friendly by realizing dynamic balance between decomposition and absorption and interlocking control of temperature and speed.

Description

TECHNICAL FIELD

[0001] The present application relates to a hydrogen fluoride production process and system, in particular to a safe, controllable and environmentally friendly production process and system for preparing electronic grade hydrogen fluoride from ammonium bifluoride, belonging to the field of hydrogen fluoride production technology. BACKGROUND

[0002] Hydrogen fluoride (HF) is a colorless, irritating gas or liquid with strong corrosive and toxic properties, which can react with glass, silicate and other materials. Its aqueous solution (hydrofluoric acid) has an irreplaceable role in the electronic industry, refrigerants, pharmaceuticals and new material synthesis. For example, in semiconductor manufacturing, high-purity electronic grade hydrogen fluoride is used for wafer cleaning and etching process; 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 electrolyte). With the rapid development of global semiconductor, photovoltaic and new energy vehicle industries, the demand for electronic grade hydrogen fluoride and high-purity hydrogen fluoride continues to grow, and the market potential is expected to be huge in the future.

[0003] However, the production, storage and use of hydrogen fluoride face serious challenges. Due to its strong corrosive property, the equipment material requirements are extremely high, and the traditional preparation process is often accompanied by a large amount of pollutants (such as fluorogypsum, fluorine-containing wastewater), which has a significant environmental pressure. In addition, the synthesis of hydrogen fluoride in the prior art relies on the fluorite-sulfuric acid route, which consumes a lot of resources and has high carbon emissions, and a safer and more environmentally friendly alternative process is urgently needed.

[0004] Currently, the industrial production methods of hydrogen fluoride mainly include: 1. Fluorite-sulfuric acid method: fluorite (CaF2) reacts with concentrated sulfuric acid to produce hydrogen fluoride, with fluorogypsum as by-product. This technology is mature and has high yield, but has problems such as high raw material consumption, difficult treatment of by-products, and severe equipment corrosion; 2. Fluorosilicic acid method: fluorosilicic acid (H2SiF6) by-product of phosphate fertilizer is used to decompose and produce hydrogen fluoride, which can reduce the dependence on fluorite, but the process is complex, energy consumption is high, and a large amount of dilute sulfuric acid by-product needs to be treated; 3. Fluorine-containing waste recovery method: ammonium bifluoride (NH4HF2) is recovered from nitrogen trifluoride waste electrolyte, and then decomposed into hydrogen fluoride. Although this method conforms to the concept of circular economy, the existing process has problems such as low recovery efficiency and insufficient product purity.

[0005] Therefore, the above methods generally have the following defects: 1. Poor safety: high temperature and high pressure reaction conditions can easily lead to hydrogen fluoride leakage risk; 2. High environmental pressure: the treatment cost of by-products (such as fluorogypsum, fluorine-containing wastewater) is high, which can easily cause environmental pollution; 3. Purity is limited: traditional process is difficult to stably produce high purity (≥98%) hydrogen fluoride, which restricts its application in high-end fields.

[0006] Although, the prior art CN111847384A discloses "a preparation method of anhydrous hydrogen fluoride", which grafts mature sulfuric acid fluorite method to prepare hydrogen fluoride industrialization technology and production device, taking alkali metal or alkaline earth metal fluoride salt as raw material, reacting with concentrated sulfuric acid, the reaction formula involved is: 2MHF2+H2SO4→M2SO4+4HF↑ or M(HF2)2+H2SO4→MSO4+4HF↑ (M is alkali metal or alkaline earth metal); CN118684193A discloses "a preparation method of hydrogen fluoride", which mixes ammonium bifluoride solid and anti-azeotropic agent and water, and then distills to obtain hydrogen fluoride acid condensate; adding water removing agent to the hydrogen fluoride acid condensate, and distilling to obtain anhydrous hydrogen fluoride, etc. But it does not solve the problems of easy leakage of hydrogen fluoride, great environmental pressure, poor quality (mainly purity) of hydrogen fluoride, etc.

[0007] Therefore, there is an urgent need for a hydrogen fluoride production process that is controllable, safe, environmentally friendly, etc. SUMMARY

[0008] To solve the problems of uncontrollable reaction, safety hazard and environmental pollution in the production of hydrogen fluoride in the prior art, a production process and system for preparing hydrogen fluoride from ammonium bifluoride are proposed. In this technical solution, ammonium bifluoride is used as raw material, and decomposition is carried out under the conditions of nitrogen atmosphere and temperature of 125-250℃ to generate a mixed gas containing hydrogen fluoride; then, through absorption by active substances, a complex (composite salt) is formed to separate hydrogen fluoride gas from other gases; subsequently, the complex is cracked under the conditions of nitrogen atmosphere and temperature of 150-200℃ to generate hydrogen fluoride gas and replace the active substances; finally, purification is carried out to obtain hydrogen fluoride gas with purity ≥98%.

[0009] Among them, based on the control of specific conditions, and based on the matching production system, the dynamic balance between decomposition and absorption is guaranteed (through the establishment of a quick response relationship between the pressure and component changes of the material in the discharge port of the absorption separator and the control parameters of the front-end decomposition reactor, such as: when the HF concentration in the discharge port of the absorption separator is greater than 2%, the decomposition temperature in the decomposition reactor is reduced; when the pressure in the discharge port of the absorption separator is too high, the N2 flow rate and partial pressure in the decomposition reactor are reduced); and through the interlocking control of temperature and speed, the safety (dynamic balance, not too high pressure), greenness (active substance-potassium / sodium bifluoride can be recycled and reused, and the cost is low), environmental protection (ammonia gas is adsorbed and then emptied, and the adsorbed ammonia gas can be reused) and other advantages of the hydrogen fluoride process are guaranteed.

[0010] In order to achieve the above technical purpose, the following technical scheme is proposed: The first object of the technical solution is to provide 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-position raw material storage tank are added to a raw material pretreater, and after drying and dehydration, dry ammonium bifluoride particles are obtained; if not dehydrated, the water in the raw material will react with the subsequently generated HF to form hydrofluoric acid, which has strong corrosiveness and brings certain influence on the equipment and subsequent operation; S2 decomposition: the dry ammonium bifluoride particles obtained in step S1 are passed into a decomposition reactor, the nitrogen atmosphere in the decomposition reactor is controlled, and the decomposition temperature is 125-250°C, to obtain a mixed gas containing nitrogen (as an equilibrium gas), hydrogen fluoride and ammonia (a small amount); Among them, the reaction formula is: NH4HF2→NH4F+HF (I); NH4HF2→2HF+NH3 (II); NH4F →HF+NH3 (III); S3 absorption: the mixed gas containing hydrogen fluoride, ammonia and nitrogen is cooled to 90-120°C by using a heat exchanger I, and then is passed into an absorption separator; under the condition of a temperature of 100-130°C in the absorption separator, the hydrogen fluoride in the mixed gas is absorbed by the active substance in the absorption separator and forms a complex (a 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 a small amount of hydrogen fluoride which is not absorbed; The tail gas containing ammonia, nitrogen and hydrogen fluoride is sequentially passed into an ammonia adsorption tower and an adsorption column (containing activated carbon or molecular sieves), the ammonia adsorption tower absorbs and removes the ammonia in the tail gas, the tail gas is then subjected to adsorption treatment (absorbing a small amount of ammonia and a small amount of hydrogen fluoride) by the adsorption column, and finally the tail gas is sent to a exhaust pipeline for external exhaust. At this time, the tail gas mainly contains nitrogen, and a small amount of ammonia and hydrogen fluoride (concentration ≤0.09 mg / m³), which meets the "Air Pollutant Emission Standard"; Among them, the active substance in the absorption separator is potassium fluoride, sodium fluoride, potassium fluoride or sodium fluoride; in the case of potassium fluoride, the reaction formula is: KHF2+ (1-3) HF→ KF· (2-4) HF; In the case of potassium fluoride, the reaction formula is: KF + HF → KHF2; In the technical solution, the active substance is limited to "potassium fluoride, sodium fluoride, potassium fluoride or sodium fluoride", which effectively avoids the use of active substances with high decomposition temperature, resulting in high energy consumption and uneconomicalness, etc. After the absorption is completed (i.e. the hydrogen fluoride gas content in the discharge port of the absorption separator is ≥0.1%. A gas concentration detector can be used for monitoring), the gas inlet pipe containing the mixed gas of nitrogen, hydrogen fluoride and ammonia gas connected with the absorption separator is closed (one end of the gas inlet pipe is connected with the decomposition reactor, and the other end is connected with the absorption separator); S4 cleavage: after the active substance in the absorption separator is saturated with hydrogen fluoride (an online detector for detecting the hydrogen fluoride concentration can be arranged at the discharge port of the absorption separator to monitor whether the hydrogen fluoride in the absorption separator is saturated. If the absorption is saturated, the hydrogen fluoride gas content in the discharge port of the absorption separator is ≥0.1%; if the absorption is not saturated, the hydrogen fluoride gas content in the discharge port of the absorption separator is <0.1%), nitrogen is introduced into the absorption separator to sweep away the remaining fluorine-containing gas; then, the temperature is raised to 150-200°C, the complex is cleaved to form a solid product and a gas product, wherein the solid product is the active substance (potassium fluoride, sodium fluoride, potassium fluoride or sodium fluoride), and the gas product is a crude hydrogen fluoride gas (mainly hydrogen fluoride, and a small amount of nitrogen); S5 purification: the obtained crude hydrogen fluoride gas is cooled to room temperature (15-30°C) by using a heat exchanger II, and then introduced into a liquefaction separator to compress the obtained crude hydrogen fluoride gas and separate the non-condensable gas to obtain hydrogen fluoride gas with a volume concentration of ≥98%, which is then introduced into a hydrogen fluoride storage tank for storage and standby; In the compression process, the nitrogen in the crude hydrogen fluoride gas is not liquefied, and the hydrogen fluoride is liquefied, so that the hydrogen fluoride and nitrogen are separated, thereby ensuring the purification of the hydrogen fluoride gas.

[0011] In the step S1 pretreatment: The circulating water temperature in the jacket of the high-level raw material storage tank is controlled at 10-35°C, the volume of the material in the high-level raw material storage tank is not more than 70% of the volume, the upper part of the high-level raw material storage tank is sealed with nitrogen with a purity of >99.9%, and the nitrogen sealing pressure is 0.3-0.6 MPa; The raw material pretreater uses dry air with a dew point of < -40°C and a temperature lower than 35°C for dehydration, and the batch processing time is 1-4 h; In the step S2 decomposition: Before the decomposition reaction starts, the decomposition reactor is replaced with nitrogen with a purity of >99.9% to ensure that the nitrogen content in the decomposition reactor is >99%, and a slight positive pressure of 10-30 KPa is maintained; 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. After holding the temperature, decomposition is carried out. 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 is functioning correctly. Without stepped temperature control, it would be difficult to determine the reactor's functionality, thereby compromising the sustainability and stability of the production process. During the decomposition reaction, the pressure inside the decomposition reactor is maintained at 50–150 kPa. In step S3 absorption: The decomposed mixed gas is introduced into heat exchanger I, and the outlet temperature of heat exchanger I is controlled to be <100℃. Before the absorption reaction begins, the gas inside the absorption separator is replaced with nitrogen gas of 99.9% or higher to ensure that the nitrogen content inside the absorption separator is >99% and to maintain a slight positive pressure of 10-30 kPa. Insert the mixed gas inlet pipe connected to heat exchanger I into the bottom of the absorption separator; during the absorption reaction, maintain the temperature inside the absorption separator at 100-130℃, and ensure that the hydrogen fluoride content in the outlet of the absorption separator is <0.1% by controlling the inlet rate of the gas (mixed gas generated in the self-decomposition reactor); 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 gas inside the absorber is replaced with nitrogen of 99.9% or higher to ensure that the nitrogen content inside the absorber is >99% and to maintain a slight positive pressure of 10-30 kPa. Then, the temperature inside the absorber separator is raised to 150–170°C and held for 1–2 hours; the temperature is then raised to 180–200°C 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 II, and the outlet temperature of heat exchanger II is controlled to be <30℃. The temperature inside the hydrogen fluoride storage tank is controlled at 10–18°C, and the hydrogen fluoride storage tank is pressurized to 0.3–1.0 MPa with nitrogen.

[0012] The second 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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 invention based on the specific circumstances.

[0020] The beneficial technical effects of adopting this technical solution are as follows: This invention proposes a production process for preparing hydrogen fluoride from ammonium bifluoride, and then, based on a phase-compatible production system, ensures a dynamic balance between decomposition and absorption; furthermore, through interlocking control of temperature and rate, it ensures the safety, greenness, and environmental friendliness of the hydrogen fluoride process. Specifically, it includes: I. High Raw Material Safety: Ammonium bifluoride is a solid compound, which is easier to store and transport safely than gaseous hydrogen fluoride. This means that the raw material is not demanding in terms of required conditions and can be obtained through resource recovery from fluorine-containing waste (such as nitrogen trifluoride waste electrolyte), reducing raw material costs and promoting a circular economy. Compared with ammonium fluoride, which is also a solid, ammonium fluoride has a theoretical boiling point of about 68°C, while ammonium bifluoride has a boiling point of about 240°C. Ammonium bifluoride is very stable in low-temperature and dry environments, which is beneficial for long-distance transportation and long-term storage. II. Strong process controllability: Through a two-stage process design of decomposition and absorption and pyrolysis purification, combined with nitrogen protection, step temperature control and adsorption and separation technology of active substances (such as potassium / sodium hydrogen fluoride), side reactions are effectively suppressed to ensure that the purity of hydrogen fluoride is ≥98%, reaching the electronic grade. III. Significant Environmental Benefits: The entire process is a closed-loop operation. The exhaust gas is treated by an ammonia adsorption tower and adsorption column to meet emission standards. The by-product ammonia water can be recycled and reused, achieving near-zero pollution emissions. IV. Equipment Corrosion Resistance Optimization: The reaction device is lined with corrosion-resistant polymers such as modified polypropylene and polytetrafluoroethylene, combined with Hastelloy key components, which significantly extends the equipment life and reduces maintenance costs. V. Particularly suitable for small-scale or irregular high-purity hydrogen fluoride demand in confined spaces: 1) Using ammonium bifluoride granules as raw material, hydrogen fluoride is obtained through pretreatment-decomposition-absorption-pyrolysis-purification, ensuring a simple production process; 2) Through the setting of decomposition reactors, absorption separators, etc., the decomposition, absorption, and pyrolysis purification are designed in stages, and combined with nitrogen protection, step temperature control, and active material (such as potassium / sodium hydrogen fluoride) adsorption and separation technology, the production process is highly controllable; 3) Safe and green (active materials can be recycled and reused at low cost), environmentally friendly (ammonia is adsorbed and then discharged, and the adsorbed ammonia can be reused), and high-purity (≥98%) hydrogen fluoride is obtained; 4) Through the synergistic effect of temperature regulating medium control valve, nitrogen control valve, pressure sensor I, temperature sensor, pressure sensor II, online detector, mixed gas control valve, etc., the dynamic balance between decomposition and absorption is ensured, achieving controllable reaction and rapid start-up and shutdown; This invention not only provides a new route for the efficient preparation of hydrogen fluoride, but also offers an innovative solution to the environmental pollution and safety hazards of traditional processes, aligning with the global trend of green transformation in the chemical industry. Attached Figure Description

[0021] Figure 1 This is a flowchart of the production process in this invention; Figure 2 This is a schematic diagram illustrating the working principle of the production system in this invention; Figure 3 This is a block diagram of the equipment structure of the production system in this invention; 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. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 This embodiment provides a production process for preparing hydrogen fluoride from ammonium bifluoride, such as: Figure 1 As shown, it includes the following steps: S1 preprocessing: The ammonium bifluoride granules in the high-level raw material storage tank 1 are added to the raw material pre-processor 2. Dry air with a dew point < -40℃ and a temperature below 35℃ is used for drying and dehydration treatment for 1 hour. After drying and dehydration, dry ammonium bifluoride granules are obtained. S2 decomposition: The decomposition reactor 3 is gas-purified with nitrogen of 99.9% or higher, and the nitrogen content in the decomposition reactor 3 is controlled to be >99%, while maintaining a slight positive pressure of 10 kPa. Then, the dried ammonium bifluoride particles obtained in step S1 are fed into the decomposition reactor 3. The decomposition reactor 3 is controlled to be in a nitrogen atmosphere, the decomposition temperature is 125°C, and the pressure is maintained at 50 kPa to obtain a mixed gas containing hydrogen fluoride, ammonia and nitrogen. More specifically, for the decomposition temperature, a stepped temperature control mode can be used: The temperature inside the decomposition reactor 3 was raised to 80℃ at a rate of 5℃ / min; the temperature inside the decomposition reactor 3 was then raised from 80℃ to 125℃ at a rate of 2℃ / min; and then the temperature was kept constant. S3 absorption: Heat exchanger I15 is used to cool the mixture of hydrogen fluoride, ammonia and nitrogen to 95°C; The gas in the absorption separator 4 is replaced with nitrogen gas of 99.9% or higher to control the nitrogen content in the decomposition reactor 3 to >99% and maintain a slight positive pressure of 10 kPa. Then, the cooled mixture of hydrogen fluoride, ammonia, and nitrogen is introduced into the absorption separator 4. Potassium hydrogen fluoride for absorbing hydrogen fluoride gas is added into the absorption separator 4. The atmosphere inside the absorption separator 4 is controlled to be nitrogen and the absorption temperature is controlled to be 100°C. The hydrogen fluoride gas content at the outlet of the absorption separator 4 is controlled to be <0.1%, resulting in a complex and tail gas (containing ammonia, nitrogen, and hydrogen fluoride). The tail gas containing ammonia, nitrogen, and hydrogen fluoride is sequentially introduced into the ammonia adsorption tower 14 and the adsorption column 17 for post-treatment before being discharged to improve environmental protection. S4 pyrolysis: After the active material is absorbed to the point of hydrogen fluoride saturation, the gas in the absorption separator 4 is replaced with nitrogen gas of 99.9% or higher to control the nitrogen content in the decomposition reactor 3 to >99% and maintain a slight positive pressure of 10 kPa. The absorption separator 4 is controlled to be in a nitrogen atmosphere and the pyrolysis temperature is 200℃. The complex is pyrolyzed to obtain crude hydrogen fluoride gas and solid product. The solid product is potassium hydrogen fluoride. More specifically, for the pyrolysis temperature, a stepped temperature control mode can be adopted: The temperature inside the absorber separator 4 is raised to 150℃ and held for 1 hour; then, the temperature is raised to 200℃ and held for 4 hours, controlling the decomposition rate of hydrogen fluoride adsorbed by the active material to be ≥99%.

[0024] S5 Purification: Using heat exchanger II16, the obtained crude hydrogen fluoride gas is cooled to room temperature and then introduced into liquefaction separator 5; nitrogen gas for liquefying hydrogen fluoride gas is added into liquefaction separator 5, and then the obtained crude hydrogen fluoride gas is compressed to obtain hydrogen fluoride gas with a volume concentration ≥98%; it is then introduced into hydrogen fluoride storage tank 6 for storage and future use.

[0025] Example 2 This embodiment provides a production process for preparing hydrogen fluoride from ammonium bifluoride, including the following steps: S1 preprocessing: The ammonium bifluoride granules in the high-level raw material storage tank 1 are added to the raw material pre-processor 2. Dry air with a dew point < -40℃ and a temperature below 35℃ is used for drying and dehydration treatment for 4 hours. After drying and dehydration, dry ammonium bifluoride granules are obtained. S2 decomposition: The decomposition reactor 3 is gas-purified with nitrogen of 99.9% or higher, and the nitrogen content in the decomposition reactor 3 is controlled to be >99%, while maintaining a slight positive pressure of 30 kPa. Then, the dried ammonium bifluoride particles obtained in step S1 are fed into the decomposition reactor 3. The decomposition reactor 3 is controlled to be in a nitrogen atmosphere, the decomposition temperature is 250°C, and the pressure is maintained at 150 kPa to obtain a mixed gas containing hydrogen fluoride, ammonia and nitrogen. More specifically, for the decomposition temperature, a stepped temperature control mode can be used: The temperature inside the decomposition reactor 3 was raised to 80℃ at a rate of 6℃ / min; the temperature inside the decomposition reactor 3 was then raised from 80℃ to 250℃ at a rate of 3℃ / min; and then the temperature was kept constant. S3 absorption: Heat exchanger I15 is used to cool the mixture of hydrogen fluoride, ammonia and nitrogen to 100°C; The gas in the absorption separator 4 is replaced with nitrogen gas of 99.9% or higher, and the nitrogen content in the decomposition reactor 3 is controlled to be >99%, maintaining a slight positive pressure of 30 kPa. Then, the cooled mixture of hydrogen fluoride, ammonia, and nitrogen is introduced into the absorption separator 4. Sodium hydrogen fluoride for absorbing hydrogen fluoride gas is added into the absorption separator 4. The atmosphere inside the absorption separator 4 is controlled to be nitrogen and the absorption temperature is controlled to be 100-130℃. The hydrogen fluoride gas content at the outlet of the absorption separator 4 is controlled to be <0.1%, resulting in a complex and tail gas (containing ammonia, nitrogen, and hydrogen fluoride). The tail gas containing ammonia, nitrogen, and hydrogen fluoride is sequentially introduced into the ammonia adsorption tower 14 and the adsorption column 17 for post-treatment before being discharged to improve environmental protection. S4 pyrolysis: After the active material is absorbed to the point of hydrogen fluoride saturation, the gas in the absorption separator 4 is replaced with nitrogen gas of 99.9% or higher to control the nitrogen content in the decomposition reactor 3 to >99% and maintain a slight positive pressure of 30 kPa. The absorption separator 4 is controlled to be in a nitrogen atmosphere and the pyrolysis temperature is 200℃. The complex is pyrolyzed to obtain crude hydrogen fluoride gas and solid product. The solid product is sodium hydrogen fluoride. More specifically, for the pyrolysis temperature, a stepped temperature control mode can be adopted: The temperature inside the absorber separator 4 is raised to 170℃ and held for 2 hours; then, the temperature is raised to 200℃ and held for 1 hour, controlling the decomposition rate of hydrogen fluoride adsorbed by the active material to be ≥99%.

[0026] S5 Purification: Using heat exchanger II16, the obtained crude hydrogen fluoride gas is cooled to room temperature and then introduced into liquefaction separator 5; nitrogen gas for liquefying hydrogen fluoride gas is added into liquefaction separator 5, and then the obtained crude hydrogen fluoride gas is compressed to obtain hydrogen fluoride gas with a volume concentration ≥98%; it is then introduced into hydrogen fluoride storage tank 6 for storage and future use.

[0027] Example 3 This embodiment provides a production process for preparing hydrogen fluoride from ammonium bifluoride, including the following steps: S1 preprocessing: The ammonium bifluoride granules in the high-level raw material storage tank 1 are added to the raw material pre-processor 2. Dry air with a dew point < -40℃ and a temperature below 35℃ is used for drying and dehydration treatment for 3 hours. After drying and dehydration, dry ammonium bifluoride granules are obtained. S2 decomposition: The decomposition reactor 3 is gas-purified with nitrogen of 99.9% or higher, and the nitrogen content in the decomposition reactor 3 is controlled to be >99%, while maintaining a slight positive pressure of 20 kPa. Then, the dried ammonium bifluoride particles obtained in step S1 are fed into the decomposition reactor 3. The decomposition reactor 3 is controlled to be in a nitrogen atmosphere, the decomposition temperature is 200℃, and the pressure is maintained at 100KPa to obtain a mixed gas containing hydrogen fluoride, ammonia and nitrogen. More specifically, for the decomposition temperature, a stepped temperature control mode can be used: The temperature inside the decomposition reactor 3 was raised to 80℃ at a rate of 8℃ / min; the temperature inside the decomposition reactor 3 was then raised from 80℃ to 200℃ at a rate of 4℃ / min; and then the temperature was kept constant. S3 absorption: Heat exchanger I15 is used to cool the mixture of hydrogen fluoride, ammonia and nitrogen to 115°C; The gas in the absorption separator 4 is replaced with nitrogen gas of 99.9% or higher to control the nitrogen content in the decomposition reactor 3 to >99% and maintain a slight positive pressure of 20 kPa. Then, the cooled mixture of hydrogen fluoride, ammonia, and nitrogen is introduced into the absorption separator 4. Sodium fluoride for absorbing hydrogen fluoride is added into the absorption separator 4. The atmosphere inside the absorption separator 4 is controlled to be nitrogen and the absorption temperature is controlled to be 100-130°C. The hydrogen fluoride content at the outlet of the absorption separator 4 is controlled to be <0.1%, resulting in a complex and tail gas (containing ammonia, nitrogen, and hydrogen fluoride). The tail gas containing ammonia, nitrogen, and hydrogen fluoride is then sequentially introduced into the ammonia adsorption tower 14 and the adsorption column 17 for post-treatment before being discharged to improve environmental friendliness. S4 pyrolysis: After the active material is absorbed to the point of hydrogen fluoride saturation, the absorber separator 4 is replaced with nitrogen gas of 99.9% or higher to control the nitrogen content in the decomposition reactor 3 to >99% and maintain a slight positive pressure of 20 kPa. The absorption separator 4 is controlled to be in a nitrogen atmosphere and the pyrolysis temperature is 180℃. The complex is pyrolyzed to obtain crude hydrogen fluoride gas and solid product. The solid product is the active substance. More specifically, for the pyrolysis temperature, a stepped temperature control mode can be adopted: The temperature inside the absorber separator 4 is raised to 160℃ and held for 1-2 hours; then, the temperature is raised to 180℃ and held for 3 hours, controlling the decomposition rate of hydrogen fluoride adsorbed by the active material to be ≥99%.

[0028] S5 Purification: Using heat exchanger II16, the obtained crude hydrogen fluoride gas is cooled to room temperature and then introduced into liquefaction separator 5; nitrogen gas for liquefying hydrogen fluoride gas is added into liquefaction separator 5, and then the obtained crude hydrogen fluoride gas is compressed to obtain hydrogen fluoride gas with a volume concentration ≥98%; it is then introduced into hydrogen fluoride storage tank 6 for storage and future use.

[0029] Example 4 Based on Examples 1-3, this example provides a production system for preparing hydrogen fluoride from ammonium bifluoride, such as... Figures 2-3 As shown, it includes an elevated raw material storage tank 1, a raw material pre-processor 2, a decomposition reactor 3, an absorption separator 4, and a liquefaction separator 5, wherein, High-level raw material storage tank 1: used to store ammonium bifluoride granules. High-level raw material storage tank 1 is connected to nitrogen inlet pipe I8. High-level raw material storage tank 1 is located in front of the work station of raw material preprocessor 2. The discharge port of high-level raw material storage tank 1 is connected to the inlet of raw material preprocessor 2. Raw material pre-processor 2: Used for drying ammonium bifluoride granules. The raw material pre-processor 2 is connected to a nitrogen inlet pipe II11 and a drying air inlet pipe 7. The discharge port of the raw material pre-processor 2 is connected to the feed port of the decomposition reactor 3. Decomposition reactor 3: Used to decompose ammonium hydrogen fluoride. Decomposition reactor 3 is connected to nitrogen inlet pipe Ⅲ18. Decomposition reactor 3 is located behind the work station of raw material preprocessor 2. The discharge port of decomposition reactor 3 is connected to the inlet of absorption separator 4. Absorption separator 4: Used to absorb and separate the generated hydrogen fluoride. Absorption separator 4 is connected to nitrogen inlet pipe IV19 and active material inlet pipe 10. Absorption separator 4 is located behind the station of decomposition reactor 3. The discharge port of absorption separator 4 is connected to the feed port of liquefaction separator 5. Liquefaction separator 5: Used to purify hydrogen fluoride. Liquefaction separator 5 is connected to a nitrogen inlet pipe V20. Liquefaction separator 5 is located behind the station of absorption separator 4. The outlet of liquefaction separator 5 is connected to a hydrogen fluoride storage tank 6, and 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. Each of the high-level raw material storage tank 1, the raw material pre-processor 2, the decomposition reactor 3, and the absorption separator 4 is equipped with a jacket, through which circulating water or steam is circulated.

[0030] 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, preventing excessive pressure), greenness (the active material - potassium / sodium hydrogen fluoride - can be recycled at low cost), and environmental protection (ammonia can be reused) of the hydrogen fluoride process, etc.

[0031] Furthermore, in the embodiments, to further ensure the dynamic balance between decomposition and absorption, the following limitations are further defined: The jacket Ⅲ outside the decomposition reactor 3 is connected to a temperature regulating medium inlet pipe. The temperature regulating medium inlet pipe is equipped with a temperature regulating medium control valve. The nitrogen inlet pipe Ⅲ18 is equipped with a nitrogen control valve and a pressure sensor Ⅰ. The decomposition reactor 3 is equipped with a temperature sensor. The outlet of the absorber separator 4 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 3 and the absorption separator 4, and a mixed gas control valve is provided on the mixed gas inlet pipe; The online detector, temperature sensor, and temperature control medium regulating valve are interlocked via electrical signals. For example, when the HF concentration at the outlet of the absorption separator 4 is greater than 2%, the decomposition temperature in the decomposition reactor 3 is reduced. Pressure sensor II, pressure sensor I, and the nitrogen control valve 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 and the mixed gas control valve are interlocked 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 using an online detector), the mixed gas inlet pipe containing nitrogen, hydrogen fluoride, and ammonia connected to the absorber separator 4 is closed.

[0032] Ultimately, a dynamic balance is achieved between decomposition and absorption.

[0033] Example 5 Based on Example 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.

[0034] 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.

[0035] Example 6 Based on Examples 4-5, in order to further improve the continuity and stability of the absorption reaction and pyrolysis separation within the absorber separator 4, as well as to enhance environmental friendliness, the following improvements are made: 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.

[0036] Example 7 Based on Examples 4-6, 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.

[0037] 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.

[0038] 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℃.

[0039] Example 8 Based on Examples 1-7, 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: Sodium hydrogen fluoride (NaHF2); 2. Equipment High-level raw material storage tank 1: carbon steel lined with modified polypropylene, with a jacketed circulating water temperature of 22℃, and the tank is filled with material at 65% 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 8cm from the bottom of the reactor and 5cm from the lid; Absorption Separator 4: Stainless steel lined with polytetrafluoroethylene, mixed gas inlet pipe inserted at the bottom, with sodium bifluoride inside as the active substance for absorption; Heat exchanger: Tubular heat exchanger, low-temperature circulating water inlet temperature 5℃; Ammonia Adsorption Tower 14: Carbon steel tank, used for adsorbing and recovering ammonia water; 5. Liquefaction Separator: Compressor; Hydrogen fluoride storage tank 6: lined with polytetrafluoroethylene.

[0040] 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 -45℃ and a temperature of 30℃ is introduced for 2.5 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 until it is < 0.5%, maintaining a slight positive pressure of 20 kPa. Then, a stepped temperature control is used: the temperature of the decomposition reactor 3 is increased from room temperature to 80℃ at a rate of 5℃ / min and held at that temperature for 1.5 hours; then increased to 150℃ at a rate of 2℃ / min and held at that temperature for 1.5 hours; finally, increased to 190℃ at a rate of 1℃ / min and held at that temperature for 3 hours, with the decomposition reaction pressure stabilizing at 150 kPa. The mixture produced by the decomposition reaction (containing HF, NH3, N2 and a small amount of ammonium fluoride) is cooled to 90°C by a tubular heat exchanger and enters the absorption separator 4. The absorption separator 4 is kept at 120°C, where sodium bifluoride fully absorbs HF, and the HF content in the outlet gas is <0.1%. The tail gas is fed into an ammonia absorption tower, where NH3 is absorbed by spraying with deionized water to obtain ammonia water with a concentration of 25%. The remaining tail gas is discharged after removing residual NH3 by an activated carbon adsorption column 17, and the residual NH3 content in the tail gas is <5 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 < 0.5%, maintaining a slight positive pressure of 20 kPa. Then, a stepped temperature control is used: the temperature is increased to 160℃ at a rate of 2℃ / min and held at that temperature for 1.5 hours; then the temperature is increased to 190℃ at a rate of 1℃ / min and held at that temperature for 3 hours, controlling the cracking rate to ≥ 99.5%. The HF gas produced by cracking is cooled by a tubular heat exchanger and then enters the compressor; the compressor is pressurized to 0.3 MPa to remove non-condensable gases, finally obtaining anhydrous hydrogen fluoride with a purity of 98.5%, which is stored in hydrogen fluoride storage tank 6 (temperature controlled at 15℃).

[0041] Under the above process conditions, after 200 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 98.5%, moisture content <0.02%.

[0042] Example 9 Based on Examples 1-7, 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: Potassium hydrogen fluoride (KHF2); 2. Equipment High-level raw material storage tank 1: carbon steel lined with polytetrafluoroethylene, with a jacketed circulating water temperature of 24℃, and the tank is filled with material to 70% of its volume; Raw material preprocessor 2: Uses a drum dryer lined with corrosion-resistant polymer; Decomposition reactor 3: Carbon steel lined with polyimide, heated by heat transfer oil in the jacket, with temperature measuring tubes inserted to 10cm from the bottom of the reactor and 8cm from the lid; Absorber Separator 4: Stainless steel lined with poly(aryletherketone) ketone, mixed gas inlet pipe inserted at the bottom (the outlet of the mixed gas inlet pipe is located in the middle of the absorbent layer), with potassium hydrogen fluoride built in as the active material for absorption; Heat exchanger: Tubular heat exchanger, low-temperature circulating water inlet temperature 8℃; 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. 5. Liquefaction Separator: Compressor; Hydrogen fluoride storage tank 6: lined with polytetrafluoroethylene.

[0043] 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 -50℃ and a temperature of 25℃ is introduced for 3.5 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 until it is < 0.3%, maintaining a slight positive pressure of 25 kPa. Then, a stepped temperature control is used: the decomposition reactor 3 is heated from room temperature to 80℃ at a rate of 7℃ / min and held at that temperature for 1.5 hours; then heated to 160℃ at a rate of 4℃ / min and held at that temperature for 2 hours; finally, heated to 205℃ at a rate of 0.8℃ / min and held at that temperature for 1.5 hours, with the decomposition reaction pressure stabilizing at 120 kPa. The mixture produced by the decomposition reaction (containing HF, NH3, N2 and a small amount of ammonium fluoride) is cooled to 100°C by a tubular heat exchanger and enters the absorption separator 4. The absorption separator 4 is kept at 115°C, where potassium hydrogen fluoride fully absorbs HF, and the HF content in the outlet gas is <0.05%. The tail gas is fed into an ammonia absorption tower, where a two-stage spray device is used to absorb NH3, resulting in ammonia water with a concentration of 28%. The remaining tail gas is discharged after the residual NH3 is removed by the activated carbon adsorption column 17, and the residual NH3 content in the tail gas is <3 ppm, which meets environmental protection requirements. (2) Pyrolysis and purification After the potassium fluoride in the absorber separator 4 is saturated, nitrogen gas (purity ≥ 99.9%) is introduced to replace the oxygen content until it is < 0.3%, maintaining a slight positive pressure of 25 kPa. Then, a stepped temperature control is used: the temperature is increased to 170℃ at a rate of 1.5℃ / min and held at that temperature for 2 hours; then, the temperature is increased to 200℃ at a rate of 0.8℃ / min and held at that temperature for 4 hours, controlling the cracking rate to ≥ 99.8%. The HF gas produced by cracking is cooled by a tubular heat exchanger and then enters the compressor; the compressor is pressurized to 0.55 MPa to remove non-condensable gases, finally obtaining anhydrous hydrogen fluoride with a purity of 99.2%, which is stored in hydrogen fluoride storage tank 6 (temperature controlled at 12℃).

[0044] Under the above process conditions, after 200 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 99.2%, moisture content <0.015%.

[0045] Example 10 Based on Examples 1-7, 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.

[0046] 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℃).

[0047] 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%.

[0048] Comparative Example 1 Based on Example 1, the difference between this comparative example and Example 1 is as follows: The pretreatment in step S1 is omitted, that is, the drying and dehydration treatment of the raw material ammonium bifluoride particles is cancelled, and the rest is the same as in Example 1.

[0049] It was found that after one day of operation, the pipelines connected to the decomposition reactor 3 (made of stainless steel) and the stirring mechanism inside the decomposition reactor 3 developed localized pitting corrosion. After three days of operation, the corrosion area expanded, and a slight leak appeared on the sealing surface inside the decomposition reactor 3, requiring shutdown for maintenance. The corrosion was concentrated in stress-concentrated areas such as welds and flange connections, presenting as brown rust products (containing ferric fluorides). Simultaneously, a large amount of white mist-like gas was generated in subsequent decomposition processes. Testing of this gas revealed free water vapor (content of 1.5–2.0 vol%). Furthermore, the hydrogen fluoride concentration in the exhaust gas discharged from the outlet of the absorption separator 4 exceeded the standard, reaching 0.8–1.2% (higher than the hydrogen fluoride gas content in Example 1: hydrogen fluoride gas content at the outlet of the absorption separator 4 <0.1%), leading to a surge in the load on the ammonia adsorption tower 14. In addition, the solid product potassium hydrogen fluoride severely agglomerated in subsequent pyrolysis processes.

[0050] Comparative Example 2 Based on Example 2, the difference between this comparative example and Example 2 is as follows: The stepped temperature control mode in step S2 is not performed, and the temperature is directly increased from room temperature to 250°C at a rate of 10°C / min, and the rest is the same as in Example 2.

[0051] It can be seen that the concentration of hydrogen fluoride in the exhaust gas discharged from the upper outlet of the absorber separator 4 exceeds the standard by 0.5-0.8% (far exceeding the design value: <0.1%); local hot spots appear inside the absorber separator 4, and the surface layer of the active material - sodium hydrogen fluoride - is sintered and caking.

[0052] Comparative Example 3 Based on Example 3, the difference between this comparative example and Example 3 is as follows: In the absorption process of step S3, heat exchanger I15 is used to cool the mixed gas containing hydrogen fluoride, ammonia and nitrogen to 80°C, and the rest is the same as in Example 1.

[0053] It can be seen that the concentration of hydrogen fluoride in the exhaust gas discharged from the upper outlet of the absorber separator 4 is consistently higher than 0.5% (higher than the design value: <0.1%); the active substance - sodium fluoride (NaF) is in powder form, and at the same time, powder appears in the pipeline connected to the upper outlet of the absorber separator 4, the pressure difference gradually increases, and even blockage occurs.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention 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 invention should be included within the protection scope of the present invention.

Claims

1. A production process for preparing hydrogen fluoride from ammonium bifluoride, characterized in that, Includes the following steps: S1 Pretreatment: Add the raw material ammonium bifluoride particles from the high-level raw material storage tank (1) to the raw material preprocessor (2), and after drying and dehydration, obtain dry ammonium bifluoride particles; S2 decomposition: The dried ammonium fluoride particles obtained in step S1 are introduced into the decomposition reactor (3), and 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 hydrogen fluoride, ammonia and nitrogen. S3 Absorption: Heat exchanger I (15) 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); active material for absorbing hydrogen fluoride gas is added into the absorption separator (4), and then the nitrogen atmosphere and absorption temperature in the absorption separator (4) are controlled to be 100-130°C to obtain a complex. S4 pyrolysis: After the active material is absorbed to the point of hydrogen fluoride saturation, the atmosphere inside the absorption separator (4) is controlled to be nitrogen and the pyrolysis temperature is 150-200℃. The complex is pyrolyzed to obtain crude hydrogen fluoride gas. S5 Purification: Using heat exchanger II (16), the obtained crude hydrogen fluoride gas is cooled to room temperature and then introduced into the liquefaction separator (5); nitrogen gas for liquefying hydrogen fluoride gas is added into the liquefaction separator (5), and then the obtained crude hydrogen fluoride gas is compressed to obtain hydrogen fluoride gas with a volume concentration ≥98%; it is then introduced into the hydrogen fluoride storage tank (6) for storage and future use.

2. The production process for preparing hydrogen fluoride from ammonium bifluoride according to claim 1, characterized in that, In step S1, dry air with a dew point < -40℃ and a temperature below 35℃ is used, and the drying and dehydration treatment time is 1 to 4 hours.

3. The production process for preparing hydrogen fluoride from ammonium bifluoride according to claim 1, characterized in that, In step S2, before the decomposition reaction begins, the decomposition reactor (3) is purged with nitrogen of 99.9% or higher to control the nitrogen content in the decomposition reactor (3) to be >99% and maintain a slight positive pressure of 10-30 kPa. During the decomposition reaction, the pressure inside the decomposition reactor (3) is controlled to be maintained at 50-150 KPa.

4. The production process for preparing hydrogen fluoride from ammonium bifluoride according to claim 1 or 3, characterized in that, In step S2, a stepped temperature control mode is adopted: The temperature inside the decomposition reactor (3) is raised to 80°C at a rate of 5-10°C / min; the temperature inside the decomposition reactor (3) is raised from 80°C to 125-250°C at a rate of 2-5°C / min; and then the temperature is kept constant.

5. The production process for preparing hydrogen fluoride from ammonium bifluoride according to claim 1, characterized in that, In step S3, before the absorption reaction begins, the absorption separator (4) is purged with nitrogen of 99.9% or higher to control the nitrogen content in the decomposition reactor (3) to be >99% and maintain a slight positive pressure of 10-30 kPa. During the absorption reaction, the hydrogen fluoride gas content in the discharge port of the absorption separator (4) is controlled to be <0.1%.

6. The production process for preparing hydrogen fluoride from ammonium bifluoride according to claim 1 or 5, characterized in that, In step S3, the active substance is potassium hydrogen fluoride, sodium hydrogen fluoride, potassium fluoride, or sodium fluoride.

7. The production process for preparing hydrogen fluoride from ammonium bifluoride according to claim 6, characterized in that, In step S3, a tail gas containing ammonia, nitrogen and hydrogen fluoride is also obtained. The tail gas containing ammonia, nitrogen and hydrogen fluoride is sequentially passed into the ammonia adsorption tower (14) and the adsorption column (17) for post-treatment.

8. The production process for preparing hydrogen fluoride from ammonium bifluoride according to claim 1, characterized in that, In step S4, before the pyrolysis reaction begins, the absorber separator (4) is purged with nitrogen of 99.9% or higher to control the nitrogen content in the decomposition reactor (3) to be >99% and maintain a slight positive pressure of 10-30 kPa.

9. The production process for preparing hydrogen fluoride from ammonium bifluoride according to claim 1 or 8, characterized in that, In step S4, a stepped temperature control mode is adopted: The temperature inside the absorber (4) is raised to 150-170°C and kept constant for 1-2 hours; then, the temperature is raised to 180-200°C and kept constant for 1-4 hours, controlling the decomposition rate of hydrogen fluoride adsorbed by the active substance to be ≥99%.

10. A production system for preparing hydrogen fluoride from ammonium bifluoride, characterized in that, The production system used in the production process for preparing hydrogen fluoride from ammonium bifluoride as described in any one of claims 1-9 includes an elevated raw material storage tank (1) for storing ammonium bifluoride particles, a raw material pre-processor (2) for drying the ammonium bifluoride particles, 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).

11. The production system for preparing hydrogen fluoride from ammonium bifluoride according to claim 10, characterized in that, The jacket Ⅲ outside the decomposition reactor (3) is connected to a temperature regulating medium inlet pipe. The temperature regulating medium inlet pipe is equipped with a temperature regulating medium control valve. The nitrogen inlet pipe Ⅲ (18) is equipped with a nitrogen control valve and a pressure sensor Ⅰ. The decomposition reactor (3) is equipped with a temperature sensor. Pressure sensor II and an online detector for detecting hydrogen fluoride concentration are installed at the outlet of the absorber separator (4); A mixed gas inlet pipe is provided between the decomposition reactor (3) and the absorption separator (4), 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.

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