High-precision mixing method for fluorine and nitrogen mixed gas

Abstract

The application discloses a high-precision mixing method of fluorine and nitrogen mixed gas, and relates to the technical field of fluorine and nitrogen mixed gas mixing, which comprises pretreatment of the gas, gas flow control mixing, dynamic mixing and post-treatment of the mixed gas.The application has the advantages that: a flow sensor adopting quantum cascade laser-induced fluorescence technology and an intelligent micro-electro-mechanical system flow controller are combined to measure and control the flow of fluorine gas, and a high-precision mass flow controller based on the acoustic vortex principle is used to control the flow of nitrogen gas, so that the flow measurement and control precision are greatly improved, the stability and reliability of a semiconductor manufacturing process are greatly improved, chip defects caused by gas mixing problems are reduced, production cost is reduced, and production efficiency is improved; graphene-ceramic composite coating is coated in a heat exchanger, so that the heat exchanger has heat conduction performance and can enhance the corrosion resistance of fluorine gas; when fluorine gas passes through the heat exchanger, heat can be rapidly transmitted through a heat pipe, and high-efficiency heat exchange is realized.

Description

Technical Field

[0001] This invention relates to the field of fluorine and nitrogen gas mixing technology, specifically a high-precision mixing method for fluorine and nitrogen mixed gas. Background Technology

[0002] Gas mixing technology plays a crucial role in many high-tech industries and scientific research fields, especially with the increasing demand for high-precision mixing of fluorine and nitrogen gases.

[0003] In the semiconductor manufacturing industry, as chip manufacturing processes continue to evolve towards greater precision, the requirements for the gas environment are becoming increasingly stringent. Fluorine or nitrogen gases are often used as key process gases. For example, in some advanced plasma etching processes, a precisely proportioned fluorine mixture (which may contain other auxiliary gases) can achieve high-precision etching of the chip's microstructures, ensuring chip performance and yield. For nitrogen mixtures, in chip manufacturing processes such as annealing, a precise nitrogen mixture can effectively protect the chip surface and prevent adverse effects such as oxidation. Traditional mixing methods are limited by factors such as equipment precision and process control, making it difficult to meet these high-precision requirements. In terms of equipment, ordinary gas flow meters have significant errors when measuring the flow rate of fluorine or nitrogen. This is because the chemical reactivity of fluorine may corrode or interfere with the measuring element. Nitrogen flow rate may also be inaccurate at low flow rates. In terms of process, the temperature, humidity, and pressure control of the mixing environment are not precise enough, leading to deviations in the gas mixing ratio.

[0004] In the field of materials science research, fluorine and nitrogen mixtures are often used in plasma treatment processes when modifying material surfaces. For example, fluorine mixtures can be used to fluorinate polymer materials, changing their surface energy and chemical stability. Nitrogen mixtures can be used to form nitrided layers on metal materials, improving their hardness and wear resistance. However, inaccurate mixture ratios can lead to uneven surface modification and fail to achieve the expected improvement in material properties.

[0005] In chemical production, some chemical reaction processes involving fluorine or nitrogen require highly precise gas mixtures to control reaction rates and selectivity. For example, in certain fluorination reactions, a precisely proportioned fluorine gas mixture can ensure that the reaction proceeds along the designed path, improve the yield of the target product, and reduce the occurrence of side reactions. For redox reactions involving nitrogen, a suitable nitrogen gas mixture helps maintain the stability of the reaction system. However, traditional mixing methods are difficult to guarantee a consistently high-precision gas mixture in large-scale chemical production, affecting production efficiency and product quality. Therefore, we propose a high-precision mixing method for fluorine and nitrogen gas mixtures. Summary of the Invention

[0006] The purpose of this invention is to provide a method for high-precision mixing of fluorine and nitrogen gas.

[0007] To address the problems mentioned in the background section, the present invention provides the following technical solution: a method for high-precision mixing of fluorine and nitrogen gas, comprising gas pretreatment, gas flow control mixing, dynamic mixing, and post-treatment of the mixed gas. The specific operation steps of the method for high-precision mixing of fluorine and nitrogen gas are as follows:

[0008] Step 1: Gas pretreatment. Fluorine gas is passed into the purification column for filtration. After filtration, it is passed into the heat exchanger, and the outlet temperature of the fluorine gas is adjusted.

[0009] Step 2: Filter the nitrogen gas through two sets of filtration devices. After filtration, pass the nitrogen gas into the deoxygenation tower for deoxygenation. After deoxygenation, control the nitrogen gas to a stable state through a heat exchanger.

[0010] Step 3: Fluorine and nitrogen are introduced into the mixing chamber for mixing. The flow rates of the two gases are controlled, and the environmental conditions in the mixing chamber are set to perform preliminary mixing of fluorine and nitrogen to obtain a preliminary mixed gas.

[0011] Step 4: Pass the pre-mixed gas mixture into a special dynamic mixer, adjust the dynamic mixer, and simultaneously perform ultrasonic treatment on the pre-mixed gas mixture. After treatment, perform plasma activation operation on the gas mixture to obtain a refined gas mixture.

[0012] Step 5: Pass the mixed gas through the filter into the pressure stabilizing tank, control the pressure inside the tank, monitor the parameters of the refined mixed gas in the pipeline, and ensure that the output refined mixed gas is in a high-precision mixed state.

[0013] As a further aspect of the present invention: In step one, the novel composite adsorbent filling the purification column is composed of metal-organic framework materials (MOFs) and a high-fluorine-affinity ionic liquid. Fluorine gas is introduced into the purification column at a flow rate of 1 L / min to 3 L / min, and the temperature of the purification column is controlled at 15℃-5℃, and the pressure is controlled between 0.122 MPa and 0.182 MPa. Under these environmental conditions, the content of hydrogen fluoride and fluorine oxides in the fluorine gas is reduced to below 0.5 ppm. The reaction of fluorine gas with trace amounts of hydrogen fluoride impurities in the purification column is as follows:

[0014]

[0015] In the above reactions, and Anions undergo proton exchange reactions. Formed after accepting protons ,form , Formed after accepting protons Similarly formed .

[0016] As a further aspect of the present invention: In step one, after the fluorine gas passes through the purification column, it is introduced into a heat exchanger, which is a micro-nano structure heat pipe technology. The heat pipe is filled with acetone with low boiling point and high thermal conductivity. The heat pipe wall is coated with a graphene ceramic composite coating. When the fluorine gas passes through the heat exchanger, the temperature is adjusted to reach 20℃-25℃. The fluorine gas pressure in the heat exchanger is maintained between 1.51MPa and 2.01MPa, and the fluorine gas temperature is controlled in a stable state, while the temperature fluctuation is reduced to within ±0.5℃.

[0017] As a further aspect of the present invention: In step two, nitrogen gas enters the first-stage filtration device. The filter membrane is a nanofiber membrane filter with a fiber diameter between 50µm and 100µm, made of polyimide carbon nanotube composite material. Nitrogen gas is passed through the first-stage nanofiber membrane filter at a flow rate of 3L / min to 6L / min, with an operating pressure of 0.2MPa to 0.3MPa.

[0018] The temperature is maintained at 15℃-25℃. The nitrogen gas after passing through the first-stage filtration is introduced into the second-stage filtration device, which is an adsorption tower based on zeolite molecular sieve. In the second-stage adsorption tower, the flow rate of nitrogen gas is adjusted to 2L / min-5L / min, the pressure is maintained between 0.15MPa and 0.25MPa, and the temperature is controlled between 20℃ and 25℃. The moisture content in the nitrogen gas is reduced to below 1ppm, and the content of small molecule organic matter is reduced to below 0.5ppm.

[0019] As a further aspect of the present invention: In step two, the deoxygenation tower is filled with a palladium-gold-nickel ternary alloy catalyst with an atomic ratio of 4:3:2. During the deoxygenation process, oxygen molecules in the nitrogen gas undergo dissociation and adsorption on the catalyst surface, and then react with a trace amount of externally supplied hydrogen gas. The reaction equation is as follows:

[0020]

[0021] Nitrogen gas is introduced into the deoxygenation tower at a flow rate of 2 L / min to 4 L / min. The temperature inside the deoxygenation tower is controlled at 25℃ to 30℃, and the pressure is maintained at 0.12 MPa to 0.18 MPa. The oxygen content in the nitrogen gas is reduced to below 0.1 ppm. After completion, the nitrogen gas is passed through a heat exchanger, where the nitrogen temperature is controlled at 20℃ to 25℃, and the nitrogen pressure inside the heat exchanger is maintained at 1.5 MPa to 2.0 MPa. The nitrogen temperature is kept in a stable state, and the temperature fluctuation is reduced to within ±0.5℃.

[0022] As a further aspect of the present invention: In step three, a flow sensor using quantum cascade laser-induced fluorescence technology is combined with an intelligent microelectromechanical system flow controller to control the fluorine gas flow rate. A high-precision mass flow controller based on the acoustic vortex street principle is used, with a vortex generator designed inside the controller. When nitrogen gas passes through, a stable vortex street is generated. The above flow control methods are used to introduce fluorine gas and nitrogen gas into the mixing chamber at flow rates of 0.5 L / min to 2 L / min and 2 L / min to 8 L / min, respectively. The inner wall of the mixing chamber is made of a novel electrostatic self-cleaning layer, the main components of which are a composite material of polytetrafluoroethylene and nano-titanium dioxide. An active pressure balancing device is used to control the pressure in the mixing chamber. A precise temperature control system is set in the mixing chamber to precisely control the temperature in the mixing chamber at 22℃ ± 0.2℃. After mixing the fluorine gas and nitrogen gas, a preliminary mixed gas is obtained.

[0023] As a further aspect of the present invention: In step four, a specially designed dynamic mixer is provided with a spiral microchannel inside. The walls of the microchannel are coated with a functional polymer film. The polymer film is supported by a composite of polyvinylidene fluoride hexafluoropropylene copolymer and MOFs. Ultrasonic transducers are uniformly arranged inside the mixer, with their operating frequency set to 30kHz-50kHz and the ultrasonic power density adjusted within the range of 10W / L-50W / L. The initial mixed gas is introduced into the dynamic mixer at a flow rate of 2.5L / min-10L / min. The ultrasonic power density and frequency are controlled according to the flow rate of the mixed gas. When the flow rate of the mixed gas is 5L / min, the ultrasonic power density is set to 30W / L and the frequency is 40kHz. The mixed gas is kept in the dynamic mixer for 1min-3min to ensure thorough mixing.

[0024] As a further aspect of the present invention: In step four, a set of magnetic field generating devices is arranged around the dynamic mixer, and the magnetic field strength is controlled to be 0.1T-0.5T. From a microscopic perspective, gas molecules are subjected to Lorentz force in the magnetic field. For molecules with a certain magnetic moment, their equation of motion is:

[0025] ;

[0026] Among them is the Lorentz force, It is the equivalent charge of the molecule. It is the speed of molecular motion. It is the magnetic field strength;

[0027] After the initial mixed gas is mixed with magnetic field assistance, it is activated by low-temperature plasma. During the operation, the plasma discharge power is controlled at 100W-500W and the discharge frequency is 10kHz-20kHz. After the operation is completed, a refined mixed gas is obtained.

[0028] As a further aspect of the present invention: In step five, the refined mixed gas is passed through a filtration device at a flow rate of 2L / min to 10L / min. The filtration device has a two-layer composite structure, the first layer being a filter screen made of MOFs and carbon nanotubes interwoven together, and the second layer being an ion exchange membrane. The operating pressure of the filtration device is maintained at 0.8MPa to 1.2MPa, and the temperature is maintained between 20℃ and 25℃. After the refined mixed gas passes through the filtration device, a high-precision mixed gas is obtained.

[0029] Compared with the prior art, the beneficial effects of the present invention by adopting the above technical solution are as follows:

[0030] This invention combines a flow sensor using quantum cascade laser-induced fluorescence technology with an intelligent microelectromechanical system (MEMS) flow controller for fluorine gas, and a high-precision mass flow controller based on the acoustic vortex shedding principle for nitrogen gas. This significantly improves flow measurement and control accuracy, greatly enhances the stability and reliability of semiconductor manufacturing processes, reduces chip defects caused by gas mixing issues, lowers production costs, and increases production efficiency. Furthermore, by coating the inside of the heat exchanger with a graphene-ceramic composite coating, not only is the heat exchanger thermally conductive, but its resistance to fluorine corrosion is also enhanced. When fluorine gas passes through the heat exchanger, the heat can be... The heat pipe can quickly transfer heat to achieve efficient heat exchange. Low-temperature plasma is generated by high-frequency discharge. The high-energy electrons, ions and free radicals in the plasma collide with fluorine and nitrogen molecules, causing the gas molecules to be excited, dissociated and ionized, generating more active groups. The flow control method of fluorine and nitrogen ensures that the two gases can enter the mixing chamber at a high-precision flow ratio. The electrostatic self-cleaning layer in the mixing chamber can prevent impurities from interfering with the mixing process. The precise temperature control system and active pressure balancing device ensure a stable mixing environment, thereby achieving the initial uniform mixing of fluorine and nitrogen.

[0031] This invention utilizes a specially designed dynamic mixer. The functional polymer film on the walls of its internal spiral microchannels facilitates the adsorption and diffusion of gas molecules. Ultrasonic treatment from an ultrasonic transducer, magnetic field-assisted mixing from a magnetic field generator, and low-temperature plasma activation promote the interaction between gas molecules from multiple dimensions, further ensuring thorough mixing of the initial mixture and yielding a refined mixture. In the post-treatment stage, a two-layer composite filter device, operating under set pressure and temperature conditions, effectively removes impurities from the mixture. A pressure stabilizing tank ensures stable output pressure that meets high-precision requirements. This series of operations enables precise control of reaction rates and selectivity in chemical production involving fluorine or nitrogen. Fluorination reactions can improve the yield of target products and reduce side reactions, while nitrogen-involved redox reactions maintain system stability, thereby comprehensively improving chemical production efficiency and product quality. (See attached figures.)

[0032] Figure 1 This is a schematic diagram of the process for mixing fluorine and nitrogen gas in an embodiment of the present invention. Detailed Implementation

[0033] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] This invention provides a high-precision mixing method for a fluorine and nitrogen mixture, comprising gas pretreatment and gas flow control.

[0035] The specific operational steps for a high-precision mixing method of fluorine and nitrogen gases, including mixing, dynamic mixing, and post-treatment of the mixed gas, are as follows:

[0036] Step 1: Gas pretreatment. Fluorine gas is passed into the purification column for filtration. After filtration, it is passed into the heat exchanger, and the outlet temperature of the fluorine gas is adjusted.

[0037] Step 2: Filter the nitrogen gas through two sets of filtration devices. After filtration, pass the nitrogen gas into the deoxygenation tower for deoxygenation. After deoxygenation, control the nitrogen gas to a stable state through a heat exchanger.

[0038] Step 3: Fluorine and nitrogen are introduced into the mixing chamber for mixing. The flow rates of the two gases are controlled, and the environmental conditions in the mixing chamber are set to perform preliminary mixing of fluorine and nitrogen to obtain a preliminary mixed gas.

[0039] Step 4: Pass the pre-mixed gas mixture into a special dynamic mixer, adjust the dynamic mixer, and simultaneously perform ultrasonic treatment on the pre-mixed gas mixture. After treatment, perform plasma activation operation on the gas mixture to obtain a refined gas mixture.

[0040] Step 5: Pass the mixed gas through the filter into the pressure stabilizing tank, control the pressure inside the tank, monitor the parameters of the refined mixed gas in the pipeline, and ensure that the output refined mixed gas is in a high-precision mixed state.

[0041] In one embodiment of the present invention: In step one, the novel composite adsorbent filling the purification column is composed of metal-organic framework materials (MOFs) and a high-fluorine-affinity ionic liquid. Fluorine gas is introduced into the purification column at a flow rate of 1 L / min to 3 L / min, and the temperature of the purification column is controlled at -15℃ to -5℃, and the pressure is controlled between 0.122 MPa and 0.182 MPa. Under the above environmental conditions, the content of hydrogen fluoride and fluorine oxides in the fluorine gas is reduced to below 0.5 ppm. The reaction of fluorine gas with trace amounts of hydrogen fluoride impurities in the purification column is as follows:

[0042] In the above reactions, and Anions undergo proton exchange reactions. Formed after accepting protons ,form , Formed after accepting protons Similarly formed .

[0043] In one embodiment of the present invention: In step one, after passing through the purification column, the fluorine gas is introduced into a heat exchanger, which is a micro-nano structured heat pipe technology. The heat pipe is filled with acetone with low boiling point and high thermal conductivity, and the heat pipe wall is coated with a graphene-ceramic composite coating. When the fluorine gas passes through the heat exchanger, the temperature is adjusted to reach 20°C-25°C, and the fluorine gas pressure in the heat exchanger is maintained between 1.51MPa-2.01MPa, so that the fluorine gas temperature is controlled in a stable state, and the temperature fluctuation is reduced to within ±0.5°C.

[0044] In one embodiment of the present invention: In step two, nitrogen gas enters the first-stage filtration device. The filter membrane is a nanofiber membrane filter with a fiber diameter between 50 μm and 100 μm and is made of polyimide-carbon nanotube composite material. Nitrogen gas is passed through the first-stage nanofiber membrane filter at a flow rate of 3 L / min to 6 L / min, with an operating pressure of 0.2 MPa to 0.3 MPa and a temperature maintained at 15°C to 25°C. The nitrogen gas after passing through the first-stage filtration is then passed into the second-stage filtration device, which is an adsorption tower based on zeolite molecular sieves. In the second-stage adsorption tower, the flow rate of nitrogen gas is adjusted to 2 L / min to 5 L / min, the pressure is maintained between 0.15 MPa and 0.25 MPa, and the temperature is controlled at 20°C to 25°C. This reduces the moisture content in the nitrogen gas to below 1 ppm and the content of small molecule organic matter to below 0.5 ppm.

[0045] In one embodiment of the present invention: In step two, the deoxygenation tower is filled with a palladium-gold-nickel ternary alloy catalyst with an atomic ratio of 4:3:2. During the deoxygenation process, oxygen molecules in the nitrogen gas undergo dissociation and adsorption on the catalyst surface, and then react with a trace amount of externally supplied hydrogen gas. The reaction equation is as follows:

[0046]

[0047] Nitrogen gas is introduced into the deoxygenation tower at a flow rate of 2L / min-4L / min. The temperature inside the deoxygenation tower is controlled at 25℃-30℃, and the pressure is maintained at 0.12MPa-0.18MPa. The oxygen content in the nitrogen gas is reduced to below 0.1ppm. After completion, the nitrogen gas is passed through a heat exchanger to control the nitrogen temperature at 20℃-25℃. The nitrogen pressure inside the heat exchanger is maintained at 1.5MPa-2.0MPa to keep the nitrogen temperature stable, while reducing temperature fluctuations to within ±0.5℃.

[0048] In one embodiment of the present invention: In step three, a flow sensor using quantum cascade laser-induced fluorescence technology is combined with an intelligent microelectromechanical system flow controller to control the flow rate of fluorine gas. A high-precision mass flow controller based on the acoustic vortex street principle is used, and the controller is designed with a vortex generator inside. When nitrogen gas passes through, a stable vortex street is generated. The above flow control methods are used to introduce fluorine gas and nitrogen gas into the mixing chamber at flow rates of 0.5 L / min-2 L / min and 2 L / min-8 L / min, respectively. The inner wall of the mixing chamber is made of a novel electrostatic self-cleaning layer, the main components of which are a composite material of polytetrafluoroethylene and nano-titanium dioxide. An active pressure balancing device is used to control the pressure in the mixing chamber. A precise temperature control system is set in the mixing chamber to precisely control the temperature in the mixing chamber at 22℃±0.2℃. After mixing fluorine gas and nitrogen gas, a preliminary mixed gas is obtained.

[0049] In one embodiment of the present invention: In step four, a specially designed dynamic mixer is provided with a spiral microchannel inside. The walls of the microchannel are coated with a functional polymer film. The polymer film is supported by a composite of polyvinylidene fluoride-hexafluoropropylene copolymer and MOFs. An ultrasonic transducer is uniformly arranged inside the mixer, with its operating frequency set to 30kHz-50kHz and the ultrasonic power density adjusted within the range of 10W / L-50W / L. The initial mixed gas is introduced into the dynamic mixer at a flow rate of 2.5L / min-10L / min. The ultrasonic power density and frequency are controlled according to the flow rate of the mixed gas. When the flow rate of the mixed gas is 5L / min, the ultrasonic power density is set to 30W / L and the frequency is 40kHz. The mixed gas is kept in the dynamic mixer for 1min-3min to ensure thorough mixing.

[0050] In one embodiment of the present invention: In step four, a set of magnetic field generating devices is arranged around the dynamic mixer, and the magnetic field strength is controlled to be 0.1T-0.5T. From a microscopic perspective, gas molecules are subjected to Lorentz force in the magnetic field. For molecules with a certain magnetic moment, their equation of motion is:

[0051] ;

[0052] Among them is the Lorentz force, It is the equivalent charge of the molecule. It is the speed of molecular motion. It is the magnetic field strength;

[0053] After the initial mixed gas is mixed with magnetic field assistance, it is activated by low-temperature plasma. During the operation, the plasma discharge power is controlled at 100W-500W and the discharge frequency is 10kHz-20kHz. After the operation is completed, a refined mixed gas is obtained.

[0054] In one embodiment of the present invention: In step five, the refined mixed gas is passed through a filtration device at a flow rate of 2L / min to 10L / min. The filtration device has a two-layer filter composite structure. The first layer is a filter screen made of MOFs and carbon nanotubes interwoven together, and the second layer is an ion exchange membrane. The operating pressure of the filtration device is maintained at 0.8MPa to 1.2MPa, and the temperature is maintained between 20°C and 25°C. After the refined mixed gas passes through the filtration device, a high-precision mixed gas is obtained.

[0055] In one embodiment of the present invention: In step one, the reaction equation is explained as follows:

[0056] ;

[0057] In this reaction, imidazole cations The tetrafluoroborate anion forms an ionic liquid, which is the key substance in the reaction. Imidazole cations have a relatively stable structure and can provide steric hindrance and a charge environment, allowing the anion to react effectively with hydrogen fluoride. The hydrogen atoms in the hydrogen fluoride molecule have strong acidity and can react with... Anions undergo proton exchange reactions. Formed after accepting protons Simultaneously, the generated compounds combine with imidazole cations, and this reaction can effectively remove hydrogen fluoride impurities from fluorine gas. It has relatively high stability in ionic liquids, thus it is fixed in the adsorbent and will not enter the fluorine gas flow again;

[0058] ;

[0059] In this reaction, and A proton exchange reaction occurs. Formed after accepting protons Similarly generated It combines with imidazole cations and, based on the coordination ability and proton accepting ability of anions in ionic liquids, selectively reacts with hydrogen fluoride to remove impurities from fluorine gas.

[0060] In one embodiment of the present invention: In step three, quantum cascade laser-induced fluorescence technology accurately measures the flow rate based on the fluorescence signal generated by fluorine molecules under specific laser excitation, with a measurement accuracy of ±0.05%. The intelligent MEMS flow controller has an ultra-fast response microvalve structure with a response time in the millisecond range. When the preset mixing ratio requires adjustment of the fluorine flow rate, the controller can quickly and accurately adjust the microvalve opening. The high-precision mass flow controller based on the acoustic vortex street principle has a specially designed vortex generator inside. When nitrogen flows through, a stable vortex street is generated. The nitrogen flow rate is determined by measuring the vortex street frequency, with an accuracy of ±0. 0.03%, while the surface of the vortex generator is coated with a titanium nitride film, which improves its wear resistance and corrosion resistance, ensuring long-term stable measurement. The inner wall of the mixing chamber adopts a new type of electrostatic self-cleaning coating, the main component of which is a composite material of polytetrafluoroethylene and nano titanium dioxide. During the mixing process, the inner wall of the mixing chamber will generate static electricity due to gas friction. This static electricity can keep the tiny particles that may adhere to the wall in a suspended state under the action of Coulomb force, and will not be deposited on the wall to affect the mixing effect. At the same time, nano titanium dioxide has photocatalytic activity under low intensity ultraviolet light source, which can decompose trace organic pollutants that may be generated during the mixing process.

[0061] In one embodiment of the present invention: In step four, since fluorine and nitrogen molecules are magnetized to different degrees in a magnetic field, the trajectories of the gas molecules change under the action of the magnetic field, increasing the probability of collisions between molecules and the degree of mixing. When the preliminary mixed gas after magnetic field-assisted mixing is activated by plasma, the nitrogen molecules react under the action of plasma as follows:

[0062] ;

[0063] A nitrogen molecule consists of two nitrogen atoms bonded by a triple bond ( Nitrogen molecules combine to form nitrogen molecules. Under the impact of high-energy electrons, nitrogen molecules absorb enough energy to break the nitrogen-nitrogen triple bond, resulting in a nitrogen molecule ( It decomposes into two nitrogen atoms. ), and the high-energy electrons after the collision ( It continues to exist in the plasma environment.

[0064] Example 1

[0065] A novel composite adsorbent composed of metal-organic frameworks (MOFs) and a high-fluorine-affinity ionic liquid is filled into a purification column. Fluorine gas is introduced into the purification column at a flow rate of 2 L / min, while the column temperature is controlled at -10℃ and the pressure at 0.15 MPa. Under these conditions, the content of hydrogen fluoride and fluorine oxides in the fluorine gas can be reduced to 0.3 ppm. In the purification column, the fluorine gas undergoes a proton exchange reaction with trace amounts of hydrogen fluoride impurities. Anions in the ionic liquid accept protons to form corresponding products. Subsequently, the fluorine gas filtered through the purification column is introduced into a heat exchanger. The heat exchanger adopts micro-nano structure heat pipe technology. The heat pipe is filled with low-boiling-point and highly thermally conductive acetone, and the heat pipe wall is coated with a graphene-ceramic composite coating. When the fluorine gas passes through the heat exchanger, its temperature is adjusted to 22℃, and the fluorine gas pressure inside the heat exchanger is maintained at 1.8 MPa, thereby keeping the fluorine gas temperature stable and controlling the temperature fluctuation range of the fluorine gas within ±0.3℃.

[0066] Nitrogen gas is first introduced into the first-stage filtration device at a flow rate of 4 L / min. This filtration device uses a nanofiber membrane filter with a fiber diameter of 80 μm, made of polyimide-carbon nanotube composite material. The operating pressure is 0.25 MPa, and the temperature is maintained at 20°C. Subsequently, the nitrogen gas passing through the first-stage filtration is introduced into the second-stage filtration device at a flow rate of 3 L / min. The second-stage filtration device is an adsorption tower based on zeolite molecular sieves. In the second-stage adsorption tower, the pressure is maintained at 0.2 MPa, and the temperature at 22°C, which removes impurities from the nitrogen gas. The moisture content was reduced to 0.8 ppm, and the small molecule organic matter content was reduced to 0.3 ppm. Then, nitrogen gas was introduced into the deoxidation tower, which was filled with a ternary alloy catalyst with a palladium-gold-nickel atomic ratio of 4:3:2. Nitrogen gas was introduced into the deoxidation tower at a flow rate of 3 L / min. Under the conditions that the temperature in the deoxidation tower was controlled at 28°C and the pressure was maintained at 0.15 MPa, the oxygen content in the nitrogen gas was reduced to 0.08 ppm. After the deoxidation operation was completed, the nitrogen gas was passed through a heat exchanger to control its temperature at 23°C and maintain its pressure at 1.8 MPa.

[0067] A flow sensor using quantum cascade laser-induced fluorescence technology is combined with an intelligent microelectromechanical system flow controller to control the fluorine gas flow rate at 1 L / min. Simultaneously, a high-precision mass flow controller based on the acoustic vortex street principle (with an internal vortex generator that produces a stable vortex street when nitrogen passes through) is used to control the nitrogen gas flow rate at 5 L / min. Then, the fluorine and nitrogen gases are introduced into a mixing chamber. The inner wall of the mixing chamber is made of a novel electrostatic self-cleaning layer, whose main components are polytetrafluoroethylene and nano-titanium dioxide composite materials. The pressure in the mixing chamber is controlled by an active pressure balancing device, and the temperature is precisely controlled at 22°C using a temperature precision control system installed in the mixing chamber. This allows for the initial mixing of the fluorine and nitrogen gases, thus producing a preliminary mixed gas.

[0068] The initial mixed gas is introduced into a specially designed dynamic mixer at a flow rate of 6 L / min. The dynamic mixer has a spiral microchannel inside, and the walls of the microchannel are coated with a functional polymer film composed of polyvinylidene fluoride-hexafluoropropylene copolymer and MOFs. Ultrasonic transducers are uniformly arranged inside the mixer, with their operating frequency set to 40 kHz and ultrasonic power density of 30 W / L. A set of magnetic field generators is set around the dynamic mixer, and the magnetic field strength is controlled to be 0.3 T. The initial mixed gas is first mixed under the assistance of the magnetic field, and then activated by low-temperature plasma. During the plasma activation operation, the plasma discharge power is controlled to be 300 W and the discharge frequency is 15 kHz. After these operations, a refined mixed gas is obtained.

[0069] The refined gas mixture is passed through a filtration device at a flow rate of 6 L / min. This filtration device has a two-layer composite structure: the first layer is a filter screen made of MOFs and carbon nanotubes, and the second layer is an ion exchange membrane. During operation, the operating pressure of the filtration device is maintained at 1.0 MPa and the temperature at 22°C. After passing through the filtration device, the refined gas mixture enters a pressure stabilizing tank. The pressure is controlled in the pressure stabilizing tank, and the parameters of the refined gas mixture in the pipeline are monitored to ensure that the output refined gas mixture is in a high-precision mixed state, thus producing a high-precision mixed gas mixture.

[0070] Example 2

[0071] A novel composite adsorbent is filled into the purification column, and fluorine gas is introduced into the purification column at a flow rate of 1.5 L / min. At the same time, the temperature of the purification column is controlled at -8℃ and the pressure at 0.16 MPa. Under these conditions, the content of hydrogen fluoride and fluorine oxides in the fluorine gas can be reduced to 0.2 ppm. The fluorine gas undergoes a proton exchange reaction with trace hydrogen fluoride impurities in the purification column. After that, the fluorine gas filtered through the purification column is introduced into a heat exchanger. When the fluorine gas passes through the heat exchanger, its temperature is adjusted to 23℃ and the fluorine gas pressure in the heat exchanger is maintained at 1.9 MPa, so that the fluorine gas temperature is kept stable and the temperature fluctuation range of the fluorine gas is controlled within ±0.2℃.

[0072] Nitrogen gas is first introduced into the first-stage filtration unit at a flow rate of 5 L / min, with an operating pressure of 0.28 MPa and a temperature maintained at 22°C. Then, the nitrogen gas, after passing through the first-stage filtration, is introduced into the second-stage filtration unit at a flow rate of 3.5 L / min. In the second-stage adsorption tower, the pressure is maintained at 0.22 MPa and the temperature at 23°C, reducing the moisture content in the nitrogen gas to 0.6 ppm and the small molecule organic matter content to 0.2 ppm. Next, the nitrogen gas is introduced into a deoxygenation tower filled with a ternary alloy catalyst with a palladium-gold-nickel atomic ratio of 4:3:2. Nitrogen gas is introduced into the deoxygenation tower at a flow rate of 3.2 L / min. Under the conditions of a temperature controlled at 27°C and a pressure maintained at 0.16 MPa, the oxygen content in the nitrogen gas is reduced to 0.05 ppm. After the deoxygenation operation is completed, the nitrogen gas is passed through a heat exchanger, where its temperature is controlled at 24°C and its pressure is maintained at 1.9 MPa.

[0073] A flow sensor using quantum cascade laser-induced fluorescence technology, combined with an intelligent microelectromechanical system (MEMS) flow controller, is used to control the flow rate of fluorine gas at 1.2 L / min. Simultaneously, a high-precision mass flow controller based on the acoustic vortex shedding principle is used to control the flow rate of nitrogen gas at 6 L / min. Then, fluorine and nitrogen gas are introduced into a mixing chamber. The pressure in the mixing chamber is controlled by an active pressure balancing device, and the temperature is precisely controlled at 22.1℃ by a temperature precision control system installed in the mixing chamber. This allows for the initial mixing of fluorine and nitrogen gas, thus producing a preliminary mixed gas.

[0074] The initial mixed gas is introduced into a specially designed dynamic mixer at a flow rate of 7 L / min. Ultrasonic transducers are uniformly arranged inside the mixer, with their operating frequency set to 45 kHz and ultrasonic power density to 35 W / L. A set of magnetic field generators is set around the dynamic mixer, with the magnetic field strength controlled at 0.4 T. The initial mixed gas is first mixed under the assistance of the magnetic field, and then activated by low-temperature plasma. During the plasma activation operation, the plasma discharge power is controlled at 400 W and the discharge frequency at 18 kHz. After these operations, a refined mixed gas is obtained.

[0075] The refined gas mixture is passed through a filtration device at a flow rate of 7 L / min. This filtration device has a two-layer composite structure: the first layer is a filter screen made of MOFs and carbon nanotubes interwoven together, and the second layer is an ion exchange membrane. During operation, the operating pressure of the filtration device is maintained at 1.1 MPa and the temperature at 23°C. After passing through the filtration device, the refined gas mixture enters a pressure stabilizing tank. The pressure is controlled in the pressure stabilizing tank, and the parameters of the refined gas mixture in the pipeline are monitored to ensure that the output refined gas mixture is in a high-precision mixed state, thus producing a high-precision gas mixture.

[0076] Based on the above two sets of embodiments, it can be concluded that gas pretreatment effectively improves the purity of fluorine and nitrogen, and through precise and stable flow control, the synergistic effect of multiple technologies such as a specially designed dynamic mixer to achieve excellent mixing effect, and the high-precision output guaranteed by gas post-treatment, the method can achieve the effect of high-precision gas mixing. This method has technical advantages and application prospects.

Claims

1. A method for high-precision mixing of fluorine and nitrogen gas, comprising gas pretreatment, gas flow control mixing, dynamic mixing, and gas post-treatment, characterized in that: The specific steps of the high-precision mixing method for fluorine and nitrogen gas are as follows: Step 1: Gas pretreatment. Fluorine gas is passed into the purification column for filtration. After filtration, it is passed into the heat exchanger, and the outlet temperature of the fluorine gas is adjusted. Step 2: Nitrogen gas is filtered through multiple stages. After filtration, it is passed into a deoxygenation tower for deoxygenation. After completion, it is passed through a heat exchanger. Step 3: Fluorine and nitrogen are introduced into the mixing chamber for mixing. The flow rates of the two gases are controlled and the environmental conditions in the mixing chamber are set to initially mix the fluorine and nitrogen to obtain a preliminary mixed gas. The flow rate of fluorine is controlled by a quantum cascade laser-induced fluorescence technology flow sensor and an intelligent microelectromechanical system flow controller, and the flow rate of nitrogen is controlled by a mass flow controller based on the acoustic vortex street principle. Step 4: Pass the pre-mixed gas mixture into a specially designed dynamic mixer, adjust the dynamic mixer, and simultaneously perform ultrasonic treatment on the pre-mixed gas mixture to obtain a refined gas mixture. The specially designed dynamic mixer has a spiral microchannel inside, and the walls of the microchannel are coated with a layer of functional polymer film. The polymer film is supported by a composite of polyvinylidene fluoride hexafluoropropylene copolymer and MOFs. Ultrasonic transducers are uniformly arranged inside the mixer. Step 5: Pass the mixed gas through the filter into the pressure stabilizing tank, control the pressure inside the tank, monitor the parameters of the refined mixed gas in the pipeline, and ensure that the output refined mixed gas is in a high-precision mixed state.

2. The method for high-precision mixing of fluorine and nitrogen gas according to claim 1, characterized in that: In step one, the composite adsorbent filling the purification column is composed of metal-organic framework materials (MOFs) and high-fluorine-affinity ionic liquid. Fluorine gas is introduced into the purification column at a flow rate of 1 L / min to 3 L / min. The temperature of the purification column is controlled between 15°C and 5°C, and the pressure is controlled between 0.122 MPa and 0.182 MPa. Under the above environmental conditions, the content of hydrogen fluoride and fluorine oxides in the fluorine gas is reduced to below 0.5 ppm.

3. The method for high-precision mixing of fluorine and nitrogen gas according to claim 1, characterized in that: In step one, after passing through the purification column, the fluorine gas is introduced into the heat exchanger, which uses micro-nano structure heat pipe technology. The heat pipe is filled with acetone with low boiling point and high thermal conductivity, and the heat pipe wall is coated with a graphene-ceramic composite coating. When the fluorine gas passes through the heat exchanger, the temperature is adjusted to reach 20℃-25℃. The fluorine gas pressure in the heat exchanger is maintained between 1.51MPa and 2.01MPa, and the temperature fluctuation is controlled within ±0.5℃.

4. The high-precision mixing method for fluorine and nitrogen mixed gas according to claim 1, characterized in that: In step two, nitrogen gas enters the first-stage filtration device. The filter membrane is a nanofiber membrane filter with a fiber diameter between 50µm and 100µm, made of polyimide-carbon nanotube composite material. Nitrogen gas is passed through the first-stage nanofiber membrane filter at a flow rate of 3L / min to 6L / min, with an operating pressure of 0.2MPa to 0.3MPa and a temperature maintained between 15℃ and 25℃. The nitrogen gas after passing through the first-stage filtration is then passed into the second-stage filtration device, which is an adsorption tower based on zeolite molecular sieves. Inside the tower, the flow rate of nitrogen was adjusted to 2L / min to 5L / min, the pressure was maintained between 0.15MPa and 0.25MPa, and the temperature was controlled between 20℃ and 25℃. The moisture content in the nitrogen was reduced to below 1ppm, and the content of small molecule organic matter was reduced to below 0.5ppm.

5. The method for high-precision mixing of fluorine and nitrogen gas according to claim 1, characterized in that: In step two, the deoxygenation tower is filled with a palladium-gold-nickel ternary alloy catalyst with an atomic ratio of 4:3:

2. During the deoxygenation process, oxygen molecules in the nitrogen gas undergo dissociation and adsorption on the catalyst surface, and then react with a trace amount of externally supplied hydrogen gas. The reaction equation is as follows: ； Nitrogen gas is introduced into the deoxidizer at a flow rate of 2 L / min to 4 L / min. The temperature inside the deoxidizer is controlled at 25℃ to 30℃, and the pressure is maintained at [missing information]. The pressure is maintained at 0.12 MPa to 0.18 MPa to reduce the oxygen content in the nitrogen to below 0.1 ppm. After completion, the nitrogen is passed through a heat exchanger to control the nitrogen temperature at 20℃ to 25℃. The nitrogen pressure in the heat exchanger is maintained at 1.5 MPa to 2.0 MPa, and the temperature fluctuation is controlled within ±0.5℃.

6. The method for high-precision mixing of fluorine and nitrogen gas according to claim 1, characterized in that: In step three, fluorine and nitrogen are introduced into the mixing chamber at flow rates of 0.5 L / min, 2 L / min, and 2 L / min, 8 L / min, respectively. The inner wall of the mixing chamber is made of an electrostatic self-cleaning layer of polytetrafluoroethylene and nano-titanium dioxide composite material. An active pressure balancing device and a precise temperature control system are used to control the temperature at 22℃±0.2℃ to obtain a preliminary mixed gas.

7. The method for high-precision mixing of fluorine and nitrogen gas according to claim 1, characterized in that: In step four, the operating frequency is set to 30kHz-50kHz, and the ultrasonic power density is adjusted within the range of 10W / L-50W / L. The initial mixed gas is introduced into the dynamic mixer at a flow rate of 2.5L / min-10L / min. The ultrasonic power density and frequency are controlled according to the flow rate of the mixed gas. When the flow rate of the mixed gas is 5L / min, the ultrasonic power density is set to 30W / L and the frequency is 40kHz. The mixed gas is kept in the dynamic mixer for 1min-3min to ensure thorough mixing.

8. The method for high-precision mixing of fluorine and nitrogen gas according to claim 1, characterized in that: In step four, a magnetic field generating device is set up around the dynamic mixer, and the magnetic field strength is controlled to be 0.1T-0.5T. After the preliminary mixed gas is mixed with magnetic field assistance, it is activated by low temperature plasma with a plasma discharge power of 100W-500W and a discharge frequency of 10kHz-20kHz to obtain a refined mixed gas.

9. The method for high-precision mixing of fluorine and nitrogen gas according to claim 1, characterized in that: In step five, the refined mixed gas is passed through a filtration device at a flow rate of 2L / min to 10L / min. The filtration device has a two-layer composite structure. The first layer is a filter screen made of MOFs and carbon nanotubes, and the second layer is an ion exchange membrane. The operating pressure of the filtration device is maintained at 0.8MPa to 1.2MPa, and the temperature is maintained between 20℃ and 25℃. After the refined mixed gas passes through the filtration device, a high-precision mixed gas is obtained.

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