A system for preparing high-purity nitrogen trifluoride by continuous absorption and analytical separation of impurity carbon tetrafluoride

Abstract

The invention discloses a system for preparing high-purity nitrogen trifluoride by continuous absorption, analysis and separation of impurity carbon tetrafluoride, which belongs to the technical field of nitrogen trifluoride preparation. The technical scheme is as follows: it comprises an absorption tower and a desorption distillation tower connected by pipelines; the absorption tower is connected with an absorption tower feed pipeline, carbon tetrafluoride and light component discharge pipelines and a solvent inlet absorption tower pipeline; a diaphragm compressor is arranged on the absorption tower feed pipeline, the diaphragm compressor is connected to the compressor feed pipeline, and an absorption tower top condenser is arranged on the top of the absorption tower; the desorption distillation tower is provided with a desorption distillation tower top condenser, a solvent recovery pipeline and a desorption distillation tower reboiler, the desorption distillation tower top condenser is connected to the nitrogen trifluoride discharge pipeline, and the end of the solvent recovery pipeline away from the desorption distillation tower is connected with a solvent storage tank, and the outlet of the solvent storage tank is connected with the solvent inlet absorption tower pipeline. The invention can realize industrial continuous production for removing carbon tetrafluoride as an impurity in nitrogen trifluoride.

Description

Technical Field

[0001] The invention relates to the technical field of nitrogen trifluoride preparation, and in particular to a system for preparing high-purity nitrogen trifluoride by continuously absorbing, analyzing and separating impurity carbon tetrafluoride. Background Art

[0002] The mainstream nitrogen trifluoride purity in the market is 4.6N purity (NF3≥99.996VOL, CF4 less than 30ppmv). As semiconductor chips continue to break through and advance, especially in the process of breaking through 7nm to 5nm and 3nm, 4.6N nitrogen trifluoride will not be able to meet the chip support needs, resulting in a significant increase in the defect rate. Similarly, in the panel industry, with the maturity and large-scale promotion of OLED screen technology, the demand for NF3 purity is also getting higher and higher.

[0003] The main impurity that affects the purity of nitrogen trifluoride is carbon tetrafluoride. Since the boiling point difference between carbon tetrafluoride and nitrogen trifluoride is 1°C, and the mixture of the two forms an azeotrope in a wide temperature and pressure range, it is difficult to separate them by conventional distillation methods. Reducing the carbon tetrafluoride content in nitrogen trifluoride is the key to improving the purity of nitrogen trifluoride, which is also the focus of technical research by nitrogen trifluoride manufacturers at home and abroad.

[0004] Regarding the method of separating carbon tetrafluoride as an impurity in nitrogen trifluoride, many companies at home and abroad are conducting research and development of different solutions and publishing relevant literature, but there are no reports of actual industrial applications. Summary of the invention

[0005] The present invention provides a system for preparing high-purity nitrogen trifluoride by continuously absorbing, analyzing and separating impurity carbon tetrafluoride, which can realize industrial continuous production for removing impurity carbon tetrafluoride in nitrogen trifluoride, achieve a breakthrough in the production process technology of high-purity nitrogen trifluoride, realize large-scale production of high-purity nitrogen trifluoride, reduce the content of impurity carbon tetrafluoride in nitrogen trifluoride to within 3ppmv, and can receive raw material gas with a maximum CF4 content of within 2500ppmv.

[0006] The technical scheme of the present invention is: a system for preparing high-purity nitrogen trifluoride by continuously absorbing, analyzing and separating impurity carbon tetrafluoride, comprising an absorption tower and a desorption distillation tower connected by pipelines; the absorption tower is connected with an absorption tower feed pipeline, a carbon tetrafluoride and light component discharge pipeline and a solvent inlet pipeline to the absorption tower; a diaphragm compressor is arranged on the absorption tower feed pipeline, the diaphragm compressor is connected to the compressor feed pipeline, and an absorption tower top condenser is arranged on the top of the absorption tower; the desorption distillation tower is provided with a desorption distillation tower top condenser, a solvent recovery pipeline and a desorption distillation tower reboiler, the desorption distillation tower top condenser is connected to a nitrogen trifluoride discharge pipeline, one end of the solvent recovery pipeline away from the desorption distillation tower is connected with a solvent storage tank, the outlet of the solvent storage tank is connected with a solvent inlet pipeline to the absorption tower through a solvent circulation pump inlet pipeline, and a solvent circulation pump is arranged on the solvent inlet pipeline to the absorption tower.

[0007] Preferably, the absorption tower kettle adopts a horizontal kettle, and a shell and tube heat exchanger is installed in the kettle.

[0008] Preferably, the absorption tower feed pipeline is arranged in the middle of the absorption tower body, and the solvent inlet absorption tower pipeline is arranged in the upper part of the absorption tower body.

[0009] Preferably, it also includes a controller and a flow meter, the flow meter is arranged on the absorption tower feed pipeline and the solvent inlet absorption tower pipeline, and the flow meter is electrically connected to the controller.

[0010] Preferably, the desorption distillation tower top condenser is arranged at the top position of the desorption distillation tower, and the desorption distillation tower reboiler is arranged at the bottom position of the desorption distillation tower.

[0011] Preferably, the top and bottom of the absorption tower and the top and bottom of the desorption distillation tower are all provided with pressure transmitters, and the pressure transmitters are electrically connected to the controller for monitoring the pressure of the top and bottom of the tower.

[0012] Preferably, the absorption tower, the desorption distillation tower and the solvent storage tank are all provided with a liquid level transmitter, and the liquid level transmitter is electrically connected to the controller for monitoring the liquid level changes in the absorption tower and the desorption distillation tower.

[0013] Preferably, temperature sensors are provided on the tower bodies of the absorption tower and the desorption distillation tower, and the temperature sensors are electrically connected to the controller for monitoring the temperature distribution and changes of each packing layer in the absorption tower and the desorption distillation tower.

[0014] Preferably, it also includes an absorption tower solvent self-circulation pipeline, and the absorption tower solvent circulation pipeline is connected to the inlet of the solvent circulation pump.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. It can remove carbon tetrafluoride as an impurity in nitrogen trifluoride and realize industrial large-scale production;

[0017] The purity of nitrogen trifluoride produced can reach 5.5N purity (nitrogen trifluoride ≥ 99.9995% vol, CF4 ≤ 3 ppmv);

[0018] 2. The system created by the present invention can receive and process crude nitrogen trifluoride with seriously excessive carbon tetrafluoride, and the purity of the produced nitrogen trifluoride can reach 5.5N purity standard; combined with the existing nitrogen trifluoride production system, it can be used to recycle high carbon tetrafluoride materials under abnormal production conditions, improve nitrogen trifluoride production yield, and reduce production costs;

[0019] 3. Compared with other solutions, the present invention has a high degree of automation and lower operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the present invention.

[0021] In the figure, 1. compressor feed pipeline; 2. diaphragm compressor; 3. absorption tower feed pipeline; 4. absorption tower; 5. absorption tower top condenser; 6. solvent inlet absorption tower pipeline; 7. carbon tetrafluoride and light component discharge pipeline; 8. solvent circulation pump; 9. absorption tower solvent self-circulation pipeline; 10. solvent circulation cooler; 11. solvent circulation pump inlet pipeline; 12. solvent storage tank; 13. desorption distillation tower; 14. desorption distillation tower top condenser; 15. nitrogen trifluoride discharge pipeline; 16. desorption distillation tower reboiler; 17. solvent recovery pipeline. DETAILED DESCRIPTION

[0022] Example 1

[0023] like Figure 1As shown, this embodiment provides a system for preparing high-purity nitrogen trifluoride by continuous absorption, analysis and separation of impurity carbon tetrafluoride, including an absorption tower 4 and a desorption distillation tower 13 connected by pipelines; the tower kettle of the absorption tower 4 adopts a horizontal tower kettle, and a shell-and-tube heat exchanger is installed in the tower kettle; the absorption tower 4 is connected with an absorption tower feed pipeline 3, a carbon tetrafluoride and light component discharge pipeline 7 and a solvent inlet absorption tower pipeline 6; the absorption tower feed pipeline 3 is arranged in the middle of the absorption tower body, and the solvent inlet absorption tower pipeline 6 is arranged on the upper part of the absorption tower body; a diaphragm compressor 2 is arranged on the absorption tower feed pipeline 3, and the diaphragm compressor 2 is connected to the compressor feed pipeline 1; the absorption tower 4 is provided with an absorption tower feed pipeline 3, and the diaphragm compressor 2 is connected to the compressor feed pipeline 1; the absorption tower 4 is provided with an absorption tower feed pipeline 3. The top condenser 5; the desorption distillation tower 13 is provided with a desorption distillation tower top condenser 14, a solvent recovery pipeline 17 and a desorption distillation tower reboiler 16, the desorption distillation tower top condenser 14 is connected to the nitrogen trifluoride discharge pipeline 15, the desorption distillation tower top condenser 14 is arranged at the top position of the desorption distillation tower 13, and the desorption distillation tower reboiler 16 is arranged at the bottom position of the desorption distillation tower 13; the end of the solvent recovery pipeline 17 away from the desorption distillation tower 13 is connected to the solvent storage tank 12, the outlet of the solvent storage tank 12 is connected to the solvent inlet absorption tower pipeline 6 through the solvent circulation pump inlet pipeline 11, and the solvent inlet absorption tower pipeline 6 is provided with a solvent circulation pump 8;

[0024] It also includes a controller and a flow meter, the flow meter is arranged on the absorption tower feed pipeline 3 and the solvent inlet absorption tower pipeline 6, and the flow meter is electrically connected to the controller; the top and bottom of the absorption tower 4 and the top and bottom of the desorption distillation tower 13 are all provided with pressure transmitters, and the pressure transmitter is electrically connected to the controller for monitoring the pressure of the top and bottom of the tower; the absorption tower 4, the desorption distillation tower 13 and the solvent storage tank 12 are all provided with liquid level transmitters, and the liquid level transmitter is electrically connected to the controller for monitoring the liquid level changes in the absorption tower 4 and the desorption distillation tower 13; temperature sensors are arranged on the tower bodies of the absorption tower 4 and the desorption distillation tower 13, and the temperature sensors are electrically connected to the controller for monitoring the temperature distribution and changes of each packing layer in the absorption tower 4 and the desorption distillation tower 13; the absorption tower solvent self-circulation pipeline 9, the solvent circulation pipeline is connected to the inlet of the solvent circulation pump 8, and is used for self-circulation of the absorption tower 4.

[0025] Working process:

[0026] Nitrogen trifluoride containing carbon tetrafluoride impurities enters the diaphragm compressor 2 through the compressor feed pipeline 1 for compression and pressure increase, and then enters the absorption tower 4 from the middle of the absorption tower 4. The solvent in the solvent storage tank 12 is pressurized by the solvent circulation pump 8 and then first passes through the solvent circulation cooler 10 to a certain temperature, and then enters the absorption tower 4 from the upper part of the absorption tower 4 for spraying. The absorption tower 4 is equipped with structured packing and distributors and other tower internals. The mixture of carbon tetrafluoride and nitrogen trifluoride and the solvent are fully in contact with the surface of the packing in the absorption tower 4. Afterwards, carbon tetrafluoride and other impurities with lower boiling points gradually gather at the top of the absorption tower 4 and are regularly discharged from the carbon tetrafluoride and light component discharge pipeline 7, and nitrogen trifluoride enters the bottom of the absorption tower 4 along with the solvent, and is transported from the bottom of the tower to the desorption distillation tower 13 through a pipeline, where the nitrogen trifluoride and the solvent are separated, and the nitrogen trifluoride is extracted from the top of the desorption distillation tower 13, and the solvent without nitrogen trifluoride in the bottom of the desorption distillation tower 13 is recovered into the solvent storage tank 12 through the solvent recovery pipeline 17 for recycling.

[0027] High-purity nitrogen trifluoride is prepared by using the system for preparing high-purity nitrogen trifluoride by continuous absorption and analysis separation of impurity carbon tetrafluoride as described above. The feed composition is shown in Table 1, and the material data output by the nitrogen trifluoride discharge pipeline 15 is shown in Table 2.

[0028] Table 1

[0029]

[0030] Table 2

[0031]

[0032] Example 2

[0033] The difference from Example 1 is that the feed gas is different from that of Example 1, and the other conditions are exactly the same as those of Example 1. The feed composition is shown in Table 3, and the material data of the nitrogen trifluoride discharge pipeline 15 are shown in Table 4.

[0034] Table 3

[0035]

[0036] Table 4

[0037]

[0038] Example 3

[0039] The difference from Example 1 is that the feed gas is different from that of Example 1, and the other conditions are exactly the same as those of Example 1. The feed composition is shown in Table 5, and the material data of the nitrogen trifluoride discharge pipeline 15 are shown in Table 6.

[0040] Table 5

[0041]

[0042] Table 6

[0043]

[0044] Example 4

[0045] The difference from Example 1 is that the feed gas is different from that of Example 1, and the other conditions are exactly the same as those of Example 1. The feed composition is shown in Table 7, and the material data of the nitrogen trifluoride discharge pipeline 15 are shown in Table 8.

[0046] Table 7

[0047]

[0048] Table 8

[0049]

[0050] Example 5

[0051] The difference from Example 1 is that the feed gas is different from that of Example 1, and the other conditions are exactly the same as those of Example 1. The feed composition is shown in Table 9, and the material data of the nitrogen trifluoride discharge pipeline 15 are shown in Table 10.

[0052] Table 9

[0053]

[0054] Table 10

[0055]

[0056] As shown in Tables 1-10 above, the system for preparing high-purity nitrogen trifluoride by continuous absorption, analysis and separation of impurity carbon tetrafluoride according to the present invention is capable of receiving and processing crude nitrogen trifluoride with seriously excessive carbon tetrafluoride content, and multiple batches of nitrogen trifluoride gas with different CF4 contents are sampled separately, and the purity of the output nitrogen trifluoride can reach 5.5N purity (nitrogen trifluoride ≥99.9995%vol, CF4≤3ppmv).

[0057] Although the present invention has been described in detail by referring to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A system for preparing high-purity nitrogen trifluoride by continuous absorption and analytical separation of impurity carbon tetrafluoride, characterized in that: It includes an absorption tower (4) and a desorption distillation tower (13) connected by a pipeline; The absorption tower (4) is connected to an absorption tower feed pipeline (3), a carbon tetrafluoride and light component discharge pipeline (7) and a solvent absorption tower feed pipeline (6); a diaphragm compressor (2) is arranged on the absorption tower feed pipeline (3), and the diaphragm compressor (2) is connected to the compressor feed pipeline (1); an absorption tower top condenser (5) is arranged on the top of the absorption tower (4); The desorption distillation tower (13) is provided with a desorption distillation tower top condenser (14), a solvent recovery pipeline (17) and a desorption distillation tower reboiler (16); the desorption distillation tower top condenser (14) is connected to a nitrogen trifluoride discharge pipeline (15); one end of the solvent recovery pipeline (17) away from the desorption distillation tower (13) is connected to a solvent storage tank (12); the outlet of the solvent storage tank (12) is connected to a solvent inlet pipeline (6) through a solvent circulation pump inlet pipeline (11); and a solvent circulation pump (8) is provided on the solvent inlet pipeline (6); It also includes a controller and a flow meter, wherein the flow meter is arranged on the absorption tower feed pipeline (3) and the solvent inlet absorption tower pipeline (6), and the flow meter is electrically connected to the controller; The top and bottom of the absorption tower (4) and the top and bottom of the desorption distillation tower (13) are both provided with pressure transmitters, and the pressure transmitters are electrically connected to the controller; Temperature sensors are provided on the tower bodies of the absorption tower (4) and the desorption and distillation tower (13), and the temperature sensors are electrically connected to the controller; It also includes an absorption tower solvent self-circulation pipeline (9), and the absorption tower solvent circulation pipeline (9) is connected to the inlet of the solvent circulation pump (8); The absorption tower (4) adopts a horizontal tower kettle, and a shell-and-tube heat exchanger is installed in the tower kettle; The absorption tower feed pipeline (3) is arranged in the middle of the absorption tower (4) tower body, and the solvent inlet absorption tower pipeline (6) is arranged in the upper part of the absorption tower (4) tower body; The desorption distillation tower top condenser (14) is arranged at the top of the desorption distillation tower (13), and the desorption distillation tower reboiler (16) is arranged at the bottom of the desorption distillation tower (13); The absorption tower (4), the desorption distillation tower (13) and the solvent storage tank (12) are all provided with a liquid level transmitter, and the liquid level transmitter is electrically connected to the controller.

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