Device and method for purifying nitrogen trifluoride by using microchannel reactor

Abstract

The invention relates to a device and a method for purifying nitrogen trifluoride by using a microchannel reactor, and belongs to the technical field of nitrogen trifluoride gas purification, the method comprises the following steps: carrying out pyrolysis, alkali washing, reduction, water removal, primary rectification and secondary rectification on NF3 electrolytic gas prepared by adopting an electrolytic method in sequence, and under the set of device and proper process conditions, the nitrogen trifluoride is purified by using a microchannel reactor. The high-purity NF3 gas with the purity of 99.995% or above can be obtained; the device comprises a pyrolysis tower, a micro-channel reaction unit, a low-temperature water removal separator and a rectification unit which are sequentially connected through pipelines. The micro-channel reactor disclosed by the invention has efficient mass transfer and heat transfer performance, so that reactants can be fully mixed and reacted within an extremely short time, and the purification efficiency is remarkably improved. In addition, through further treatment of the rectification unit, impurities can be effectively removed, high-purity nitrogen trifluoride gas is obtained, and the purity can reach 99.995 vol% or above.

Description

Technical Field

[0001] The invention relates to the field of nitrogen trifluoride gas purification, and in particular to a device and method for purifying nitrogen trifluoride by using a microchannel reactor. Background Art

[0002] Nitrogen trifluoride (NF3) is a plasma gas with excellent etching ability. It is often used as a semiconductor material cleaning agent. It is an essential material for the production of semiconductors, displays, and solar cell industries. It is the gas with the largest demand in the electronic specialty gas market. While the rapid development of nitrogen trifluoride preparation technology has generated huge economic benefits, the purification equipment in the nitrogen trifluoride purification process is susceptible to raw material corrosion, short operating time, and high maintenance frequency. These problems have become bottlenecks that nitrogen trifluoride manufacturers need to solve urgently.

[0003] CN113247870B discloses a device for preparing high-purity nitrogen trifluoride gas. The device uses NF3 electrolytic gas prepared by electrolysis to perform secondary pyrolysis, cooling, water washing, reduction, alkali washing, water removal and secondary distillation in sequence, and can obtain high-purity NF3 gas with a purity of more than 99.995 vol%. However, this method has some defects. The device for preparing high-purity nitrogen trifluoride gas has too many purification equipments in a single production line, occupies a large area, and has low relative purification efficiency.

[0004] CN220578931U discloses a nitrogen trifluoride purification system. The system includes an alkali washing tower, a reduction tower, a water ring evacuation pump, a dehydration tower, a low-temperature dehydration cooler, a nitrogen trifluoride buffer tank, a crude product membrane press, a first rectification precooler, a first rectification tower, a second rectification tower, a third rectification tower, a fourth rectification tower and a first finished product tank, which are sequentially connected through pipelines. The purification system undergoes a simple alkali washing and reduction process, and the reaction process is insufficient, and impurities cannot be fully removed.

[0005] Therefore, the present invention proposes a device and method for purifying nitrogen trifluoride. Compared with traditional treatment methods, the present invention can effectively reduce the treatment cost of nitrogen trifluoride, increase production efficiency, improve the purity of nitrogen trifluoride, and meet green environmental protection requirements. Summary of the invention

[0006] In view of the defects existing in the current purification technology, the present invention aims to provide a device and method for purifying nitrogen trifluoride using a microchannel reactor. Compared with the traditional purification device, the footprint is reduced, the continuous automatic adjustment is carried out, and the operation difficulty and workload of the employees are reduced; at the same time, the purification efficiency is improved, the purity of nitrogen trifluoride is increased, and the maintenance and repair operations involved in the purification equipment during the purification process are reduced.

[0007] The specific technical scheme of the device and method for purifying nitrogen trifluoride using a microchannel reactor of the present invention is as follows:

[0008] A device for purifying nitrogen trifluoride using a microchannel reactor comprises a pyrolysis tower, a microchannel reaction unit, a low-temperature water removal separator and a distillation unit which are sequentially connected by pipelines;

[0009] The pyrolysis tower is provided with a feed inlet and a feed valve at the lower part and a gas outlet at the upper part;

[0010] The microchannel reaction unit comprises a first microchannel reactor, a gas-liquid separator and a second microchannel reactor which are sequentially connected by pipelines; the feed port of the first microchannel reactor is connected to a potassium hydroxide storage tank through a pipeline, and the feed port of the second microchannel reactor is also connected to a sodium sulfite storage tank through a pipeline;

[0011] The gas outlet of the pyrolysis tower is connected to the feed inlet of the first microchannel reactor through a pipeline;

[0012] The top of the potassium hydroxide storage tank is provided with a batching port, the interior of the potassium hydroxide storage tank is provided with a stirring device, and the bottom is provided with a discharge port and a discharge valve;

[0013] The first microchannel reactor is provided with an air inlet and a feed inlet at the lower part, and a discharge port at the upper part;

[0014] The gas-liquid separator is provided with a feed inlet at the top, a gas outlet at the top, and a liquid outlet at the bottom;

[0015] The sodium sulfite storage tank is provided with a batching port at the top, a stirring device is provided inside the sodium sulfite storage tank, and a discharge port and a discharge valve are provided at the bottom;

[0016] The second microchannel reactor is provided with an air inlet and a feed inlet at the lower part, and a discharge port at the upper part;

[0017] The low-temperature dehydration separator is provided with a feed inlet in the middle, a gas outlet at the top, and a liquid outlet at the bottom. The feed inlet of the low-temperature dehydration separator is connected to the discharge port of the second microchannel reactor through a pipeline;

[0018] The distillation unit comprises a diaphragm compressor, a first distillation tower and a second distillation tower connected in sequence by pipelines;

[0019] The top air outlet of the low-temperature water removal separator is connected to the feed port of the diaphragm compressor through a pipeline; the first distillation tower is provided with a feed port at the top and a discharge port at the bottom; the secondary distillation tower is provided with a feed port in the middle, a sewage outlet at the bottom and an NF3 air outlet at the top.

[0020] Preferably, a first regulating valve is provided on the pipeline between the pyrolysis tower and the first microchannel reactor; a first vacuum pump and a second regulating valve are provided on the pipeline between the first microchannel reactor and the potassium hydroxide storage tank; a second vacuum pump and a third regulating valve are provided on the pipeline between the second microchannel reactor and the sodium sulfite storage tank; a fourth regulating valve is provided on the pipeline between the low-temperature water removal separator and the diaphragm compressor; a fifth regulating valve is provided on the pipeline between the diaphragm compressor and the first distillation tower; and a sixth regulating valve is provided on the pipeline between the first distillation tower and the second distillation tower.

[0021] Preferably, the internal structures of the first microchannel reactor and the second microchannel reactor are spherical, heart-shaped or umbrella-shaped.

[0022] The present invention also provides a method for purifying nitrogen trifluoride using a microchannel reactor, which is carried out using an apparatus for purifying nitrogen trifluoride using a microchannel reactor, comprising the following steps:

[0023] S1. The primary NF3 electrolytic gas prepared by electrolysis is introduced into a pyrolysis tower, and the polyfluoride in the primary NF3 electrolytic gas undergoes pyrolysis reaction to generate fluorine gas and nitrogen gas, thereby obtaining an intermediate A;

[0024] S2, feeding the intermediate A and potassium hydroxide solution into the first microchannel reactor, reacting to remove fluorine gas, hydrogen fluoride and carbon dioxide, and obtaining the intermediate B;

[0025] The intermediate A is fed into the first microchannel reactor through the first regulating valve; the potassium hydroxide solution in the potassium hydroxide storage tank is fed into the first microchannel reactor through the first vacuum pump and the second regulating valve;

[0026] S3, sending the intermediate B into a gas-liquid separator, and obtaining a gaseous intermediate C after gas-liquid separation;

[0027] S4, sending the intermediate C and the sodium sulfite solution into the second microchannel reactor, reacting to remove oxygen difluoride and oxygen, and obtaining the intermediate D; the sodium sulfite solution in the sodium sulfite storage tank is sent into the second microchannel reactor through the second vacuum pump and the third regulating valve;

[0028] S5. The intermediate D is passed through a low-temperature water removal separator to remove water, thereby obtaining an intermediate E;

[0029] S6. After the intermediate E enters the diaphragm compressor through the fourth regulating valve for compression, it enters the first distillation tower through the fifth regulating valve to remove light impurities, and then enters the second distillation tower through the sixth regulating valve to remove heavy impurities, thereby obtaining NF3 gas with a purity of more than 99.995 vol%.

[0030] Preferably, the reaction temperature of the pyrolysis tower is 180-350° C., and the reaction pressure is 0.3-1.25 MPa.

[0031] Preferably, the reaction temperature of the first microchannel reactor is 0-55°C, and the reaction pressure is 0.25-1.2 MPa; the reaction temperature of the second microchannel reactor is 0-55°C, and the reaction pressure is 0.15-1.1 MPa.

[0032] Preferably, the operating temperature in the gas-liquid separator is 0-60°C, and the operating pressure is 0.2-1.15 MPa.

[0033] Preferably, the operating temperature in the low-temperature water removal separator is -140 to -80°C, and the operating pressure is 0.10 to 1.05 MPa.

[0034] Preferably, the pressure at the inlet of the diaphragm compressor is 0.1-1.05 MPa, and the pressure at the outlet is 0.4-1.2 MPa; the operating temperature and pressure of the first distillation tower are -140--90°C and 0.38-1.15 MPa, respectively, and the operating temperature and pressure of the second distillation tower are -150--100°C and 0.32-1.10 MPa, respectively.

[0035] Preferably, the feed amount of intermediate A in the first microchannel reactor can reach up to 1600kg / h, the feed amount of potassium hydroxide solution can reach up to 1800kg / h, and the concentration of potassium hydroxide solution is 2.5-4.5mol / L; the feed amount of intermediate C in the second microchannel reactor is up to 1550kg / h, the feed amount of sodium sulfite solution is up to 2000kg / h, and the concentration of sodium sulfite solution is 2-5mol / L.

[0036] The present invention provides a device and method for purifying nitrogen trifluoride using a microchannel reactor, which has significant beneficial effects compared to traditional purification technologies, including the following advantages:

[0037] 1. The present invention adopts microchannel reactor technology, and the device of the present invention realizes a compact design of the equipment, significantly reduces the floor space, and improves the space utilization rate. At the same time, the pipeline connections between the units are compact and orderly, which is convenient for overall layout and installation, and reduces the requirements for the production site.

[0038] 2. The device of the present invention integrates an automatic control system, which can realize continuous automatic adjustment of the operating parameters of each unit without excessive manual intervention. This not only reduces the operating difficulty and workload of employees, but also improves the stability and safety of the production process; by adjusting the valve to control the feed amount and reaction conditions, the device can flexibly respond to production needs of different scales and changes in raw material quality, enhancing the adaptability of the system.

[0039] 3. The microchannel reactor of the present invention has efficient mass transfer and heat transfer performance, so that the reactants can be fully mixed and reacted in a very short time, thereby significantly improving the purification efficiency. In addition, through further treatment by the distillation unit, impurities can be effectively removed to obtain high-purity nitrogen trifluoride gas with a purity of more than 99.995 vol%.

[0040] 4. The device of the present invention reduces unnecessary energy and material consumption by precisely controlling reaction conditions and operating parameters during the purification process. At the same time, the high efficiency of the microchannel reactor also reduces the generation of reaction by-products, which is beneficial to environmental protection and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a structural schematic diagram of the nitrogen trifluoride purification device of the present invention;

[0042] Figure 2 It is a schematic diagram of the heart-shaped structure inside the microchannel reactor of the present invention;

[0043] Figure 3 It is a schematic diagram of the spherical structure inside the microchannel reactor of the present invention;

[0044] Figure 4 It is a schematic diagram of the umbrella-shaped structure inside the microchannel reactor of the present invention;

[0045] Explanation of the markings in the figure: 1. Pyrolysis tower; 2. First regulating valve; 3. Potassium hydroxide storage tank; 4. First vacuum pump; 5. Second regulating valve; 6. First microchannel reactor; 7. Gas-liquid separator; 8. Sodium sulfite storage tank; 9. Second vacuum pump; 10. Third regulating valve; 11. Second microchannel reactor; 12. Low-temperature water removal separator; 13. Fourth regulating valve; 14. Diaphragm compressor; 15. Fifth regulating valve; 16. First distillation tower; 17. Sixth regulating valve; 18. Second distillation tower. DETAILED DESCRIPTION

[0046] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0047] Device Example 1

[0048] like Figure 1 As shown, a device for purifying nitrogen trifluoride using a microchannel reactor according to the present invention is shown. The purification device includes a pyrolysis tower 1, a microchannel reaction unit, a low-temperature water removal separator 12 and a distillation unit which are sequentially connected by pipelines.

[0049] The microchannel reaction unit includes a first microchannel reactor 6, a gas-liquid separator 7 and a second microchannel reactor 11 which are connected in sequence by pipelines; the feed port of the first microchannel reactor 6 is connected to the discharge port of the potassium hydroxide storage tank 3 through a pipeline, and the feed port of the second microchannel reactor 11 is also connected to the discharge port of the sodium sulfite storage tank 8 through a pipeline.

[0050] A dosing port is provided on the top of the potassium hydroxide storage tank 3, a stirring device is provided inside the potassium hydroxide storage tank 3, and a discharge port and a discharge valve are provided at the bottom; a dosing port is provided on the top of the sodium sulfite storage tank 8, a stirring device is provided inside the sodium sulfite storage tank 8, and a discharge port and a discharge valve are provided at the bottom.

[0051] The first microchannel reactor 6 is provided with an air inlet and a feed inlet at the bottom, and a discharge port at the top; the second microchannel reactor 11 is provided with an air inlet and a feed inlet at the bottom, and a discharge port at the top; the internal structures of the first microchannel reactor 6 and the second microchannel reactor 11 are spherical, heart-shaped or umbrella-shaped, such as Figure 2-4 shown.

[0052] A feed inlet and a feed valve are provided at the lower part of the pyrolysis tower 1, and a gas outlet is provided at the upper part; the gas outlet of the pyrolysis tower 1 is connected to the feed inlet of the first microchannel reactor 6 through a pipeline.

[0053] The gas-liquid separator 7 is provided with a feed inlet at the top, a gas outlet at the top, and a liquid outlet at the bottom.

[0054] The low-temperature dehydration separator 12 has a feed inlet in the middle, a gas outlet at the top, and a liquid outlet at the bottom. The feed inlet of the low-temperature dehydration separator 12 is connected to the outlet of the second microchannel reactor 11 through a pipeline.

[0055] The distillation unit includes a diaphragm compressor 14, a first distillation tower 16 and a second distillation tower 18 which are connected in sequence by pipelines.

[0056] The top outlet of the low-temperature water removal separator 12 is connected to the feed port of the diaphragm compressor 14 through a pipeline; the first distillation tower 16 is provided with a feed port at the top and a discharge port at the bottom; the secondary distillation tower is provided with a feed port in the middle, a sewage outlet at the bottom, and a NF3 outlet at the top.

[0057] A first regulating valve 2 is arranged on the pipeline between the pyrolysis tower 1 and the first microchannel reactor 6; a first vacuum pump 4 and a second regulating valve 5 are arranged on the pipeline between the first microchannel reactor 6 and the potassium hydroxide storage tank 3; a second vacuum pump 9 and a third regulating valve 10 are arranged on the pipeline between the second microchannel reactor 11 and the sodium sulfite storage tank 8; a fourth regulating valve 13 is arranged on the pipeline between the low-temperature water removal separator 12 and the diaphragm compressor 14; a fifth regulating valve 15 is arranged on the pipeline between the diaphragm compressor 14 and the first distillation tower 16; a sixth regulating valve 17 is arranged on the pipeline between the first distillation tower 16 and the second distillation tower 18; high-purity nitrogen trifluoride can be produced by controlling the opening of all regulating valves.

[0058] Method Example 1

[0059] The present invention also provides a method for purifying nitrogen trifluoride using a microchannel reactor, which is carried out using the above-mentioned device for purifying nitrogen trifluoride using a microchannel reactor, and comprises the following steps:

[0060] The components of the initial NF3 electrolytic gas were analyzed, and the results are shown in Table 1.

[0061] S1, the primary NF3 electrolytic gas prepared by electrolysis is passed into the pyrolysis tower 1, and the polyfluoride (N x F y ) undergoes a pyrolysis reaction to generate fluorine gas (F2) and nitrogen gas (N2) to obtain an intermediate A;

[0062] The reaction temperature of pyrolysis tower 1 is 280°C and the reaction pressure is 0.8MPa.

[0063] S2, sending the intermediate A and the potassium hydroxide solution into the first microchannel reactor 6, wherein the gas and the liquid are contacted multiple times in the first microchannel reactor, and the fluorine gas (F2), hydrogen fluoride (HF) and carbon dioxide (CO2) are fully reacted to remove the fluorine gas (F2), hydrogen fluoride (HF) and carbon dioxide (CO2), and the intermediate B is obtained;

[0064] The intermediate A is fed into the first microchannel reactor 6 through the first regulating valve 2; the potassium hydroxide solution in the potassium hydroxide storage tank 3 is fed into the first microchannel reactor 6 through the first vacuum pump 4 and the second regulating valve 5; in the potassium hydroxide storage tank, the potassium hydroxide solution is prepared when the internal liquid volume is less than 15%;

[0065] Among them, the feed rate of intermediate A is 1200 kg / h, the feed rate of potassium hydroxide solution is 1400 kg / h, the concentration of potassium hydroxide solution is 3.21 mol / L, the reaction temperature of the first microchannel reactor 6 is 35° C., and the reaction pressure is 0.75 MPa.

[0066] S3, sending the intermediate B to the gas-liquid separator 7, and obtaining the gaseous intermediate C after gas-liquid separation;

[0067] The operating temperature in the gas-liquid separator 7 is 42° C. and the operating pressure is 0.7 MPa.

[0068] S4, sending the intermediate C and the sodium sulfite solution into the second microchannel reactor 11, in the second microchannel reactor, the gas and the liquid are contacted for multiple times, and the oxyfluoride (OF2) and oxygen (O2) are fully reacted to remove, so as to obtain the intermediate D; the sodium sulfite solution in the sodium sulfite storage tank 8 is sent into the second microchannel reactor 11 through the second vacuum pump 9 and the third regulating valve 10; in the sodium sulfite storage tank, the sodium sulfite solution is prepared when the internal liquid volume is less than 15%;

[0069] Among them, the feed rate of intermediate C is 1080 kg / h, the feed rate of sodium sulfite solution is 1530 kg / h, the concentration of sodium sulfite solution is 3.6 mol / L, the reaction temperature of the second microchannel reactor 11 is 34° C., and the reaction pressure is 0.65 MPa.

[0070] S5, intermediate D passes through a low-temperature water removal separator 12 to remove water, thereby obtaining intermediate E;

[0071] The operating temperature in the low-temperature water removal separator 12 is -104°C and the operating pressure is 0.6MPa.

[0072] S6, the intermediate E enters the diaphragm compressor 14 through the fourth regulating valve 13 for compression, then enters the first distillation tower 16 through the fifth regulating valve 15 to remove light impurities, and then enters the second distillation tower 18 through the sixth regulating valve 17 to remove heavy impurities. The pressure at the inlet of the diaphragm compressor 14 is 0.6MPa, and the pressure at the outlet is 0.8MPa; the operating temperature and pressure of the first distillation tower 16 are -123°C and 0.76MPa, respectively, and the operating temperature and pressure of the second distillation tower 18 are -131°C and 0.68MPa, respectively. The first distillation can remove the light impurities in the intermediate E, and the second distillation can remove the heavy impurities. After removing the impurities, the product NF3 gas is obtained. The product NF3 gas is subjected to component analysis, and the NF3 purity is greater than 99.995vol%. The results are detailed in Table 1.

[0073] Method Example 2

[0074] The present invention also provides a method for purifying nitrogen trifluoride using a microchannel reactor, which is carried out using the above-mentioned device for purifying nitrogen trifluoride using a microchannel reactor, and comprises the following steps:

[0075] S1, the primary NF3 electrolytic gas prepared by electrolysis is introduced into a pyrolysis tower 1, and the polyfluoride in the primary NF3 electrolytic gas undergoes pyrolysis reaction to generate fluorine gas and nitrogen gas, thereby obtaining an intermediate A;

[0076] The reaction temperature of pyrolysis tower 1 is 180°C and the reaction pressure is 0.3MPa.

[0077] S2, feeding the intermediate A and potassium hydroxide solution into the first microchannel reactor 6, reacting to remove fluorine gas, hydrogen fluoride and carbon dioxide to obtain intermediate B;

[0078] The intermediate A is fed into the first microchannel reactor 6 through the first regulating valve 2; the potassium hydroxide solution in the potassium hydroxide storage tank 3 is fed into the first microchannel reactor 6 through the first vacuum pump 4 and the second regulating valve 5;

[0079] Among them, the feed rate of intermediate A is 1000 kg / h, the feed rate of potassium hydroxide solution is 12 kg / h, the concentration of potassium hydroxide solution is 2.5 mol / L, the reaction temperature of the first microchannel reactor 6 is 0° C., and the reaction pressure is 0.25 MPa.

[0080] S3, sending the intermediate B to the gas-liquid separator 7, and obtaining the gaseous intermediate C after gas-liquid separation;

[0081] The operating temperature in the gas-liquid separator 7 is 0°C and the operating pressure is 0.2 MPa.

[0082] S4, sending the intermediate C and the sodium sulfite solution into the second microchannel reactor 11, reacting to remove the oxygen difluoride and oxygen, and obtaining the intermediate D; the sodium sulfite solution in the sodium sulfite storage tank 8 is sent into the second microchannel reactor 11 through the second vacuum pump 9 and the third regulating valve 10;

[0083] Among them, the feed rate of intermediate C is 950 kg / h, the feed rate of sodium sulfite solution is 1400 kg / h, the concentration of sodium sulfite solution is 2 mol / L, the reaction temperature of the second microchannel reactor 11 is 0° C., and the reaction pressure is 0.15 MPa.

[0084] S5, intermediate D passes through a low-temperature water removal separator 12 to remove water, thereby obtaining intermediate E;

[0085] The operating temperature in the low-temperature water removal separator 12 is -140°C and the operating pressure is 0.10 MPa.

[0086] S6 and the intermediate E enter the diaphragm compressor 14 through the fourth regulating valve 13 for compression, and then enter the first distillation tower 16 through the fifth regulating valve 15 to remove light component impurities, and then enter the second distillation tower 18 through the sixth regulating valve 17 to remove heavy component impurities. The pressure at the inlet of the diaphragm compressor 14 is 0.1MPa, and the pressure at the outlet is 0.4MPa; the operating temperature and pressure of the first distillation tower 16 are -140°C and 0.38MPa, respectively, and the operating temperature and pressure of the second distillation tower 18 are -150°C and 0.32MPa, respectively. After removing impurities, the product NF3 gas is obtained. The product NF3 gas is subjected to component analysis, and the NF3 purity is greater than 99.995vol%. The results are detailed in Table 1.

[0087] Method Example 3

[0088] The present invention also provides a method for purifying nitrogen trifluoride using a microchannel reactor, which is carried out using the above-mentioned device for purifying nitrogen trifluoride using a microchannel reactor, and comprises the following steps:

[0089] S1. The primary NF3 electrolytic gas prepared by electrolysis is introduced into a pyrolysis tower 1. The polyfluoride in the primary NF3 electrolytic gas undergoes pyrolysis reaction to generate fluorine gas and nitrogen gas, thereby obtaining an intermediate A. The reaction temperature of the pyrolysis tower 1 is 350° C. and the reaction pressure is 1.25 MPa.

[0090] S2, feeding the intermediate A and potassium hydroxide solution into the first microchannel reactor 6, reacting to remove fluorine gas, hydrogen fluoride and carbon dioxide to obtain intermediate B;

[0091] The intermediate A is fed into the first microchannel reactor 6 through the first regulating valve 2; the potassium hydroxide solution in the potassium hydroxide storage tank 3 is fed into the first microchannel reactor 6 through the first vacuum pump 4 and the second regulating valve 5;

[0092] Among them, the feed rate of intermediate A is 1600 kg / h, the feed rate of potassium hydroxide solution is 1800 kg / h, the concentration of potassium hydroxide solution is 4.5 mol / L, the reaction temperature of the first microchannel reactor 6 is 55° C., and the reaction pressure is 1.2 MPa.

[0093] S3, sending the intermediate B to the gas-liquid separator 7, and obtaining the gaseous intermediate C after gas-liquid separation;

[0094] The operating temperature in the gas-liquid separator 7 is 60° C. and the operating pressure is 1.15 MPa.

[0095] S4, feeding the intermediate C and the sodium sulfite solution into the second microchannel reactor 11, reacting to remove the oxygen difluoride and oxygen to obtain the intermediate D; the sodium sulfite solution in the sodium sulfite storage tank 8 is fed into the second microchannel reactor 11 through the second vacuum pump 9 and the third regulating valve 10; wherein, the feed amount of the intermediate C is 1550kg / h, the feed amount of the sodium sulfite solution is 2000kg / h, the concentration of the sodium sulfite solution is 5mol / L, the reaction temperature of the second microchannel reactor 11 is 55°C, and the reaction pressure is 1.1MPa.

[0096] S5, intermediate D passes through a low-temperature water removal separator 12 to remove water, thereby obtaining intermediate E;

[0097] The operating temperature in the low-temperature water removal separator 12 is -80°C and the operating pressure is 1.05MPa.

[0098] S6 and the intermediate E enter the diaphragm compressor 14 through the fourth regulating valve 13 for compression, and then enter the first distillation tower 16 through the fifth regulating valve 15 to remove light component impurities, and then enter the second distillation tower 18 through the sixth regulating valve 17 to remove heavy component impurities. The pressure at the inlet of the diaphragm compressor 14 is 1.05MPa, and the pressure at the outlet is 1.2MPa; the operating temperature and pressure of the first distillation tower 16 are -90°C and 1.15MPa, respectively, and the operating temperature and pressure of the second distillation tower 18 are -100°C and 1.10MPa, respectively. After removing impurities, the product NF3 gas is obtained. The product NF3 gas is subjected to component analysis, and the NF3 purity is greater than 99.995vol%. The results are detailed in Table 1.

[0099] Table 1 Component analysis of primary NF3 electrolytic gas and product NF3 gas

[0100]

[0101] Comparative Example 1

[0102] The device used in this comparative example to prepare high-purity nitrogen trifluoride gas mainly includes a pyrolysis tower 1, a water washing tower, a reduction tower, an alkali washing tower, a water removal tower, a diaphragm compressor 14, a first distillation tower 16 and a second distillation tower 18 which are connected in sequence by pipelines.

[0103] Compared with the device embodiment 1, the difference between this comparative example is that the microchannel reaction unit and the low-temperature water removal separator 12 are replaced by a water washing tower, a reduction tower, an alkali washing tower and a water removal tower.

[0104] The method for preparing high-purity nitrogen trifluoride gas using the above comparative example device comprises the following steps:

[0105] (1) NF3 electrolysis gas passes through the first regulating valve and passes through the pyrolysis tower 1 to remove N x F y, to obtain intermediate A;

[0106] The temperature and pressure in the pyrolysis tower 1 are 350°C and 0.8MPa respectively;

[0107] (2) Intermediate A enters a water washing tower for water washing to remove part of the fluorine gas and hydrogen fluoride, then enters a reduction tower for reduction to remove oxidizing gases such as oxygen difluoride and oxygen, then enters an alkali washing tower for alkali washing to neutralize carbon dioxide, trace amounts of acidic impurities such as hydrogen fluoride, then enters a dehydration tower to remove water vapor, then enters a first distillation tower 16 for distillation to remove light impurities, and finally enters a second distillation tower 18 for distillation to remove heavy impurities, and collects the product discharged from the de-weighting tower, which is high-purity NF3 gas;

[0108] Among them, the working temperature and working pressure of the pyrolysis tower 1 are 270°C and 0.80MPa respectively; the working temperature and working pressure of the water washing tower are 37°C and 0.75MPa respectively; the working temperature and working pressure of the reduction tower are 36°C and 0.70MPa respectively; the working temperature and working pressure of the alkali washing tower are 34°C and 0.65MPa respectively; the working temperature and working pressure of the water removal tower are -103°C and 0.60MPa respectively; the inlet pressure of the diaphragm compressor 14 is 0.60MPa, and the outlet pressure is 0.8MPa; the working temperature and working pressure of the first distillation tower 16 and the second distillation tower 18 are both -123°C and 0.76MPa.

[0109] The components of the high-purity NF3 gas prepared by the comparative method were analyzed, and the results are shown in Table 2;

[0110] Table 2 High-purity NF3 gas prepared in comparative example

[0111]

[0112] Compared with method example 1, the present embodiment adopts a microchannel reactor in method example 1 so that the reactants can be fully mixed and reacted in a very short time, thereby significantly improving the purification efficiency and product concentration.

[0113] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A device for purifying nitrogen trifluoride using a microchannel reactor, characterized in that: It comprises a pyrolysis tower (1), a microchannel reaction unit, a low-temperature water removal separator (12) and a distillation unit which are sequentially connected by pipelines; The microchannel reaction unit comprises a first microchannel reactor (6), a gas-liquid separator (7) and a second microchannel reactor (11) which are sequentially connected by pipelines; the feed port of the first microchannel reactor (6) is connected to a potassium hydroxide storage tank (3) via a pipeline, and the feed port of the second microchannel reactor (11) is also connected to a sodium sulfite storage tank (8) via a pipeline; The distillation unit comprises a diaphragm compressor (14), a first distillation tower (16) and a second distillation tower (18) which are sequentially connected by pipelines; The gas outlet of the pyrolysis tower (1) is connected to the feed inlet of the first microchannel reactor (6) via a pipeline; The feed port of the low-temperature dehydration separator (12) is connected to the discharge port of the second microchannel reactor (11) via a pipeline; the top air outlet of the low-temperature dehydration separator (12) is connected to the feed port of the diaphragm compressor (14) via a pipeline.

2. The device for purifying nitrogen trifluoride using a microchannel reactor according to claim 1, characterized in that: A first regulating valve (2) is arranged on the pipeline between the pyrolysis tower (1) and the first microchannel reactor (6); a first vacuum pump (4) and a second regulating valve (5) are arranged on the pipeline between the first microchannel reactor (6) and the potassium hydroxide storage tank (3); a second vacuum pump (9) and a third regulating valve (10) are arranged on the pipeline between the second microchannel reactor (11) and the sodium sulfite storage tank (8); a fourth regulating valve (13) is arranged on the pipeline between the low-temperature water removal separator (12) and the diaphragm compressor (14); a fifth regulating valve (15) is arranged on the pipeline between the diaphragm compressor (14) and the first distillation tower (16); and a sixth regulating valve (17) is arranged on the pipeline between the first distillation tower (16) and the second distillation tower (18); the internal structures of the first microchannel reactor (6) and the second microchannel reactor (11) are spherical, heart-shaped or umbrella-shaped.

3. A method for purifying nitrogen trifluoride using a microchannel reactor, based on the device according to any one of claims 1 to 2, characterized in that: The method comprises the following steps: S1, introducing the primary NF3 electrolytic gas prepared by electrolysis into a pyrolysis tower (1), whereby the polyfluoride in the primary NF3 electrolytic gas undergoes pyrolysis reaction to generate fluorine and nitrogen, thereby obtaining an intermediate A; S2, feeding the intermediate A and potassium hydroxide solution into the first microchannel reactor (6), reacting to remove fluorine gas, hydrogen fluoride and carbon dioxide, and obtaining the intermediate B; The intermediate A is fed into the first microchannel reactor (6) through the first regulating valve (2); the potassium hydroxide solution in the potassium hydroxide storage tank (3) is fed into the first microchannel reactor (6) through the first vacuum pump (4) and the second regulating valve (5); S3, sending the intermediate B to a gas-liquid separator (7), and obtaining a gaseous intermediate C after gas-liquid separation; S4, sending the intermediate C and the sodium sulfite solution into the second microchannel reactor (11), reacting to remove the oxygen difluoride and oxygen, and obtaining the intermediate D; the sodium sulfite solution in the sodium sulfite storage tank (8) is sent into the second microchannel reactor (11) through the second vacuum pump (9) and the third regulating valve (10); S5, intermediate D passes through a low temperature water removal separator (12) to remove water to obtain intermediate E; S6 and the intermediate E enter the diaphragm compressor (14) through the fourth regulating valve (13) for compression, then enter the first distillation tower (16) through the fifth regulating valve (15) to remove light impurities, and then enter the second distillation tower (18) through the sixth regulating valve (17) to remove heavy impurities, thereby obtaining NF3 gas with a purity of more than 99.995 vol%.

4. The method for purifying nitrogen trifluoride using a microchannel reactor according to claim 3, characterized in that: The reaction temperature of the pyrolysis tower (1) is 180-350° C., and the reaction pressure is 0.3-1.25 MPa.

5. The method for purifying nitrogen trifluoride using a microchannel reactor according to claim 3, characterized in that: The reaction temperature of the first microchannel reactor (6) is 0-55°C, and the reaction pressure is 0.25-1.2 MPa; the reaction temperature of the second microchannel reactor (11) is 0-55°C, and the reaction pressure is 0.15-1.1 MPa.

6. The method for purifying nitrogen trifluoride using a microchannel reactor according to claim 3, characterized in that: The operating temperature in the gas-liquid separator (7) is 0-60°C, and the operating pressure is 0.2-1.15 MPa.

7. The method for purifying nitrogen trifluoride using a microchannel reactor according to claim 3, characterized in that: The operating temperature in the low-temperature water removal separator (12) is -140 to -80°C, and the operating pressure is 0.10 to 1.05 MPa.

8. The method for purifying nitrogen trifluoride using a microchannel reactor according to claim 3, characterized in that: The pressure at the inlet of the diaphragm compressor (14) is 0.1-1.05 MPa, and the pressure at the outlet is 0.4-1.2 MPa; the operating temperature and pressure of the first distillation tower (16) are -140--90°C and 0.38-1.15 MPa, respectively, and the operating temperature and pressure of the second distillation tower (18) are -150--100°C and 0.32-1.10 MPa, respectively.

9. The method for purifying nitrogen trifluoride using a microchannel reactor according to claim 3, characterized in that: The feed rate of the intermediate A in the first microchannel reactor (6) is 1000-1600 kg / h, the feed rate of the potassium hydroxide solution is 1200-1800 kg / h, and the concentration of the potassium hydroxide solution is 2.5-4.5 mol / L.

10. The method for purifying nitrogen trifluoride using a microchannel reactor according to claim 3, characterized in that: The feed rate of the intermediate C in the second microchannel reactor (11) is 950-1550 kg / h, the feed rate of the sodium sulfite solution is 1400-2000 kg / h, and the concentration of the sodium sulfite solution is 2-5 mol / L.

Images