Production system and method for producing electronic grade boron trifluoride

Abstract

The application relates to a production system and a production method of electronic-grade boron trifluoride, and the production system comprises a first filter, a first dust remover, a first adsorption tower, a second adsorption tower, a second dust remover, a second filter, a pre-fractionating tower, a light-removing tower, a heavy-removing tower, a third filter, an intermediate storage tank and a diaphragm compressor which are sequentially connected; the adsorption temperature of the first adsorption tower is 10-35 DEG C, the adsorption temperature of the second adsorption tower is -20-0 DEG C; the fractionating pressure of the pre-fractionating tower is 1.3-2.5 MPa; the fractionating pressure of the light-removing tower is 1.2-2.4 MPa; and the fractionating pressure of the heavy-removing tower is 1.0-2.2 MPa. The application has the advantages of reasonable process, less equipment investment, simple operation, continuous and stable production of high-purity boron trifluoride, large production capacity, high yield, meeting the requirements of various indexes after purification, the purity of the produced boron trifluoride being above 99.999%, stable quality, application in the semiconductor industry and other related industries, better utilization of cold and heat, and low production cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical purification technology, in particular to a production system and method of electronic-grade boron trifluoride. BACKGROUND

[0002] The boron trifluoride is an important raw material widely used in organic chemical industry, which is used as an acid catalyst for esterification, alkylation, polymerization, isomerization, sulfonation, nitration reaction in many organic chemical reactions, and also used for preparing halogenated boron, elemental boron, borane, borohydride and other borides.

[0003] The high-purity boron trifluoride (BF3) gas can be used in electronic industry and optical fiber industry, and can be used as a raw material for preparing optical fiber preform, and is a P-type doping source for silicon and germanium epitaxy, diffusion and ion implantation process. As a boron dopant, high-purity BF3 is used in silicon ion implantation, and the produced chip has the characteristics of high integration and high density, and is smaller in size and better in performance.

[0004] Due to the requirements of "ultra-purity" and "ultra-clean" for electronic gas, the impurity content in electronic special gas is controlled at ppm level or even ppb level. In recent years, with higher performance and smaller size of electronic components, the etching precision of semiconductor devices is required to be higher and higher, and the purity of the gas is required to be higher and higher. The trace impurities contained in the gas can cause defects in products with high-density integrated circuits. The purity of high-purity boron trifluoride used in large-scale integrated circuits is required to be greater than 99.999%. Therefore, the research on the purification technology of boron trifluoride is of great significance to the development of electronic industry. SUMMARY

[0005] Therefore, it is necessary to provide a production system and method of electronic-grade boron trifluoride.

[0006] To achieve the above-mentioned purpose, the present application provides a technical solution:

[0007] A production system of electronic-grade boron trifluoride, characterized in that the production system comprises a first filter, a first dust remover, a first adsorption tower, a second adsorption tower, a second dust remover, a second filter, a pre-distillation tower, a light-removing tower, a heavy-removing tower, a third filter, an intermediate storage tank and a diaphragm compressor connected in sequence.

[0008] The adsorption temperature of the first adsorption tower is 10-35℃, and the adsorption temperature of the second adsorption tower is -20-0℃.

[0009] The distillation pressure of the pre-distillation tower is 1.3-2.5MPa, the distillation pressure of the light-removing tower is 1.2-2.4MPa, and the distillation pressure of the heavy-removing tower is 1.0-2.2MPa.

[0010] Preferably, one end of the first filter is provided with a first valve and a second valve, the other end of the first filter is connected with the first dust remover, one end of the second filter is provided with a third valve and a fourth valve, and the fourth valve is arranged between the second filter and the pre-distillation column.

[0011] Preferably, the pre-distillation column comprises a first bottom reboiler, a first column body and a first overhead condenser.

[0012] Preferably, the light-removing column comprises a second bottom reboiler, a second column body and a second overhead condenser.

[0013] Preferably, the heavy-removing column comprises a third bottom reboiler, a third column body and a third overhead condenser.

[0014] A production method of electronic-grade boron trifluoride, and a production system thereof, comprising the steps of:

[0015] The first adsorption column and the second adsorption column are heated and purged with dry nitrogen, the heating of the first adsorption column and the second adsorption column is turned off, and the production system of the boron trifluoride is vacuumized.

[0016] The crude boron trifluoride is introduced into the first adsorption column and the second adsorption column through the first filter and the first dust remover, then purified in the pre-distillation column through the second dust remover and the second filter, and then deeply purified in the light-removing column and the heavy-removing column, and the high-purity boron trifluoride after purification is stored in an intermediate storage tank through the third filter, and compressed by a diaphragm compressor to obtain high-purity bottled boron trifluoride.

[0017] Preferably, the flow rate of the boron trifluoride to be purified and introduced into the pre-distillation column is 1 kg / h to 10 kg / h, and the heavy component flow rate discharged from the bottom of the column is 0.05 kg / h to 0.5 kg / h.

[0018] Preferably, the flow rate of the boron trifluoride to be purified and introduced into the light-removing column is 0.95 kg / h to 9.5 kg / h, and the light component flow rate discharged from the top of the column is 0.02 kg / h to 0.2 kg / h.

[0019] Preferably, the flow rate of the boron trifluoride to be purified and introduced into the heavy-removing column is 0.93 kg / h to 9.3 kg / h, the heavy component flow rate discharged from the bottom of the column is 0.05 kg / h to 0.5 kg / h, and the top take-off rate is 0.88 kg / h to 8.8 kg / h.

[0020] Preferably, the reflux ratio of the pre-distillation column is 30 to 170, the reflux ratio of the light-removing column is 2000 to 8000, and the reflux ratio of the heavy-removing column is 40 to 180.

[0021] The beneficial effects of the present application are as follows:

[0022] The present application has reasonable process, less equipment investment, simple operation, and can continuously and stably produce high-purity boron trifluoride with large production capacity and high yield. After purification, all indexes meet the requirements, the purity of the produced BF3 is above 99.999%, the quality is stable, and it can be used in semiconductor industry and other related industries. The problems of equipment corrosion and environmental pollution are solved. The cold and heat can be better utilized, and the production cost is lower. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Flow chart of the production system of electronic-grade boron trifluoride.

[0024] In the figure, 100 is a first filter, 101 is a first valve, 102 is a second valve, 110 is a second filter, 111 is a third valve, 112 is a fourth valve, 120 is a third filter, 200 is a first dust remover, 210 is a second dust remover, 300 is a first adsorption tower, 310 is a second adsorption tower, 320 is a third adsorption tower, 400 is a pre-distillation tower, 410 is a first tower bottom reboiler, 420 is a first tower body, 430 is a first tower top condenser, 500 is a light-removing tower, 510 is a second tower bottom reboiler, 520 is a second tower body, 530 is a second tower top condenser, 600 is a heavy-removing tower, 610 is a third tower bottom reboiler, 620 is a third tower body, 630 is a third tower top condenser, 700 is an intermediate storage tank, and 800 is a diaphragm compressor. DETAILED DESCRIPTION

[0025] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below in combination with specific examples.

[0026] In the examples, the test methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0027] A production system of electronic-grade boron trifluoride, the production system comprises a first filter 100, a first dust remover 200, a first adsorption tower 300, a second adsorption tower 310, a second dust remover 210, a second filter 110, a pre-distillation tower 400, a light-removing tower 500, a heavy-removing tower 600, a third filter 120, an intermediate storage tank 700, and a diaphragm compressor 800 connected in sequence.

[0028] The adsorption temperature of the first adsorption tower 300 is 10-35℃, and the adsorption temperature of the second adsorption tower 310 is -20-0℃. The adsorption depth of the first adsorption tower 300 and the second adsorption tower 310 is different, and the adsorption force is stronger at low temperature.

[0029] The distillation pressure of the pre-distillation column 400 is 1.3 MPa-2.5 MPa; the distillation pressure of the light-removing column 500 is 1.2 MPa-2.4 MPa; and the distillation pressure of the heavy-removing column 600 is 1.0 MPa-2.2 MPa. The columns are set to different pressures to provide driving force for the gas entering the next column, and the gas flows from the column with high pressure to the column with low pressure.

[0030] Specifically, the first filter 100 and the second filter 110 are used to filter the adsorbent and other solid particles, and the third filter 120 is used to remove metal particles.

[0031] In an embodiment, one end of the first filter 100 is provided with a first valve 101 and a second valve 102, the other end of the first filter 100 is connected with the first dust collector 200, one end of the second filter 110 is provided with a third valve 111 and a fourth valve 112, and the fourth valve 112 is arranged between the second filter 110 and the pre-distillation column 400.

[0032] In an embodiment, the pre-distillation column 400 includes a first column bottom reboiler 410, a first column body 420, and a first column top condenser 430.

[0033] In an embodiment, the light-removing column 500 includes a second column bottom reboiler 510, a second column body 520, and a second column top condenser 530.

[0034] In an embodiment, the heavy-removing column 600 includes a third column bottom reboiler 610, a third column body 620, and a third column top condenser 630.

[0035] A production method of electronic-grade boron trifluoride, and a production system thereof, including the steps of:

[0036] S100. Heating the first adsorption column 300 and the second adsorption column 310, purging with dry nitrogen, closing the heating of the first adsorption column 300 and the second adsorption column 310, and vacuumizing the production system of boron trifluoride.

[0037] Specifically, the first adsorption column 300 and the second adsorption column 310 are heated to 150℃-300℃, the first valve 101 and the fourth valve 112 are closed, the second valve 102 and the third valve 111 are opened, dry nitrogen is introduced for purging, the flow rate is 10 kg / h-50 kg / h, the pressure is 0.2 MPa-1.5 MPa, after purging for 10 h-20 h, the heating is stopped, the nitrogen purging is stopped after the temperature returns to room temperature, the second valve 102 and the third valve 111 are closed, and the production system of boron trifluoride is vacuumized to remove the nitrogen.

[0038] S200. Opening the first valve 101 and the fourth valve 112, the crude boron trifluoride gas is decompressed to a pressure of 1.5-3.0 MPa, and then enters the first adsorption tower 300 and the second adsorption tower 310 for adsorption, with the adsorption pressure of the first adsorption tower 300 and the second adsorption tower 310 being 1.5-3.0 MPa. The crude boron trifluoride gas then passes through the second dust remover 210 and the second filter 110, and then enters the pre-distillation tower 400 for purification. The pre-distillation tower 400 is operated under the conditions of a tower bottom temperature of -50.7 to -32.7°C, a tower top temperature of -51.5 to -34.0°C, and a distillation pressure of 1.3-2.5 MPa. The purified boron trifluoride gas then passes through the third filter 120 and is stored in the intermediate storage tank 700, and is compressed by a diaphragm compressor to obtain high-purity bottled boron trifluoride.

[0039] Specifically, the pre-distillation tower 400 discharges heavy components at the bottom and gas phase at the top, which enters the pre-distillation tower 400 top condenser. The pre-distillation tower 400 top condenser is a split condenser. After condensation, the liquid phase returns and the gas phase enters the middle of the light-removing tower 500. The pre-distillation tower 400 bottom liquid passes through the bottom reboiler, and part of it is discharged as heavy components.

[0040] The light-removing tower 500 is operated under the conditions of a tower bottom temperature of -53.0 to -34.8°C, a tower top temperature of -53.9 to -36.0°C, and a distillation pressure of 1.2-2.4 MPa. The light-removing tower 500 discharges light components at the top, and the bottom liquid enters the bottom reboiler of the light-removing tower 500, and part of it is discharged to the heavy-removing tower 600 for distillation.

[0041] The heavy-removing tower 600 is operated under the conditions of a tower bottom temperature of -57.3 to -37.2°C, a tower top temperature of -57.8 to -37.6°C, and a distillation pressure of 1.0-2.2 MPa. The heavy-removing tower 600 discharges gas phase at the top, which enters the heavy-removing tower 600 top condenser. The heavy-removing tower 600 top condenser is a split condenser. After condensation, the liquid phase returns and the gas phase is discharged as electronic-grade boron trifluoride after passing through the second filter 110, and enters the intermediate storage tank 700, which is compressed by a diaphragm compressor to obtain high-purity CO bottled product. The heavy-removing tower 600 bottom liquid enters the bottom reboiler of the heavy-removing tower 600, and part of it is discharged as heavy component impurities.

[0042] The pre-distillation tower 400, the light-removing tower 500, and the heavy-removing tower 600 all use a refrigerant as a cold source, and the second adsorption tower 310 also uses a refrigerant as a cold source.

[0043] The nitrogen tail gas purged from the first adsorption tower 300 and the second adsorption tower 310, the heavy components purged from the pre-fractionation tower 400 and the light components purged from the light component removal tower 500 are all subjected to tail gas treatment in the third adsorption tower 320.

[0044] The temperature for conveying the boron trifluoride to be purified is -20°C to 30°C;

[0045] The flow rate of the boron trifluoride conveyed into the first adsorption tower 300 and the second adsorption tower 310 is 1 kg / h to 10 kg / h.

[0046] The flow rate of the boron trifluoride conveyed into the pre-fractionation tower 400 to be purified is 1 kg / h to 10 kg / h, and the heavy component discharge flow rate at the bottom of the tower is 0.05 kg / h to 0.5 kg / h.

[0047] The flow rate of the boron trifluoride conveyed into the light component removal tower 500 to be purified is 0.95 kg / h to 9.5 kg / h, and the light component discharge flow rate at the top of the tower is 0.02 kg / h to 0.2 kg / h.

[0048] The flow rate of the boron trifluoride conveyed into the heavy component removal tower 600 to be purified is 0.93 kg / h to 9.3 kg / h, the heavy component discharge flow rate at the bottom of the tower is 0.05 kg / h to 0.5 kg / h, and the top take-off rate is 0.88 kg / h to 8.8 kg / h.

[0049] In an embodiment, the reflux ratio of the pre-fractionation tower 400 is 30 to 170;

[0050] In an embodiment, the reflux ratio of the light component removal tower 500 is 2000 to 8000;

[0051] In an embodiment, the reflux ratio of the light component removal tower 500 is 40 to 180;

[0052] The pre-fractionation tower 400, the light component removal tower 500 and the heavy component removal tower 600 are packed fractionation towers;

[0053] The packing of the light component removal tower 500 and the heavy component removal tower 600 is θ ring, triangular spiral or expanded hole plate; the material of the packing is stainless steel or nickel; the diameter of the packing is 2 mm to 20 mm, preferably 2 mm to 10 mm;

[0054] The material of the pre-fractionation tower 400, the light component removal tower 500 and the heavy component removal tower 600 is stainless steel or nickel;

[0055] The height of the pre-fractionation tower 400 is 3 m to 7 m, preferably 4 m to 6 m;

[0056] The height of the light component removal tower 500 is 5 m to 10 m, preferably 6 m to 8 m;

[0057] The height of the heavy component removal tower 600 is 10 m to 20 m, preferably 12 m to 18 m;

[0058] The diameter of the pre-distillation column of the pre-distillation tower 400 is 60-100 mm, preferably 60-80 mm;

[0059] The diameter of the distillation column of the light-removing tower 500 and the heavy-removing tower 600 is 60-150 mm, preferably 80-130 mm;

[0060] In an embodiment, the production system of the electronic-grade boron trifluoride further comprises a third adsorption tower 320 for adsorbing boron trifluoride in the exhaust tail gas, and the first adsorption tower 300, the second adsorption tower 310 and the third adsorption tower 320 have a diameter of 50-300 mm and a height of 0.5-3 m;

[0061] The adsorbent in the first adsorption tower 300 and the second adsorption tower 310 is molecular sieve, activated carbon or the like;

[0062] The adsorbent in the third adsorption tower 320 is a basic adsorbent such as calcium hydroxide and calcium oxide;

[0063] The filtering precision of the first filter 100 and the second filter 110 is 0.003-0.5 microns.

[0064] 1. The present application provides a production method of electronic-grade boron trifluoride gas, which is continuous operation, simple equipment, low investment, easy maintenance, simple operation, large production capacity, high product yield and good economy;

[0065] 2. The present application provides a production method of electronic-grade boron trifluoride gas, which can reduce the content of silicon tetrafluoride close to the boiling point of boron trifluoride to below 3 ppm, and obtain boron trifluoride with a purity of more than 99.999%.

[0066] 3. The present application provides a production method of electronic-grade boron trifluoride gas, which uses the combination of adsorption and distillation to reduce the contents of HF, CO2 and SO2 to below 1 ppm, and the contents of CF4 and H2 to below 0.5 ppm.

[0067] 4. The present application provides a production method of electronic-grade boron trifluoride gas, which uses the method of distillation to reduce N2 to below 2 ppm and O2 to below 1 ppm.

[0068] 5. The present application provides a production method of electronic-grade boron trifluoride gas, which uses a refrigerator to cool, the temperature is easy to control, the heat loss is small, the distillation operation pressure is high, and the energy consumption can be saved compared with distillation near the boiling point, and the cold energy can be fully utilized.

[0069] 6. The present application provides a method for producing electronic grade boron trifluoride gas, which uses an adsorption tower and a low temperature adsorption tower for adsorption, a pre-distillation tower for pre-distillation, a light removal tower for light removal, and a heavy removal tower for heavy removal, thereby effectively preventing the system from being blocked due to condensation under low temperature conditions and reducing the corrosion of equipment.

[0070] 7. The present application provides a method for producing electronic grade boron trifluoride gas, which controls the parameters of rectification and adsorption, so that the total impurity content is less than 10 ppm, while achieving the purpose of reducing energy consumption.

[0071] 8. The present application provides a method for producing electronic grade boron trifluoride gas, in which the tail gas in the production process is completely absorbed, so that the environment is not polluted and the environmental protection requirements are met.

[0072] 9. The present application provides a method for producing electronic grade boron trifluoride gas, which produces high-purity boron trifluoride products with stable quality, stable operation, safe operation, and is suitable for large-scale continuous industrial production.

[0073] 10. The present application provides a production device for electronic grade boron trifluoride gas, which is suitable for the production method of electronic grade boron trifluoride gas described in the present application, and obtains high-purity boron trifluoride with a purity of more than 99.999%.

[0074] Example 1

[0075] The composition of the crude boron trifluoride gas to be purified is shown in Table 1.

[0076] Table 1 Composition of raw gas in Example 1

[0077] Component [H2] [N2] O2 CF4 CO2 HF SiF4 SO2 Content / ppm 100 12 5 30 60 16 3058 8224

[0078] The system for producing electronic grade boron trifluoride from crude boron trifluoride in this example includes a first adsorption tower, a second adsorption tower, and a third adsorption tower with a diameter of 50 mm and a height of 0.5 m. The pre-distillation tower, the light removal tower, and the heavy removal tower are stainless steel packed towers, with stainless steel θ rings with a diameter of 2 mm as the packing. The pre-distillation tower has a height of 3 m and a diameter of 60 mm, the light removal tower has a height of 5 m and a diameter of 60 mm, and the heavy removal tower has a height of 10 m and a diameter of 60 mm. The first filter, the second filter, and the third filter have a filtering precision of 0.003 microns.

[0079] The operation method is as follows:

[0080] Heating the first and second adsorption towers to 150℃, closing the first and fourth valves, opening the second and third valves, and purging with dry nitrogen at a flow rate of 10 kg / h and a pressure of 0.2 MPa for 10 h. Then, stop heating, and stop purging with nitrogen after the temperature returns to room temperature. Close the second and third valves, and vacuumize the system to remove nitrogen.

[0081] Opening the first and fourth valves, and reducing the pressure of the industrial boron trifluoride gas to be purified. The gas is then introduced into the first and second adsorption towers at a flow rate of 1 kg / h and a pressure of 1.5 MPa via the first filter and first dust collector. The adsorption pressure is 1.5 MPa, the adsorption temperature of the first adsorption tower is 10℃, and the adsorption temperature of the second adsorption tower is -20℃.

[0082] The crude boron trifluoride gas after adsorption is introduced into the middle of the pre-fractionation tower at a flow rate of 1 kg / h via the second dust collector and second filter. The pre-fractionation tower is fractionated at a tower bottom temperature of -50.7℃, a tower top temperature of -51.5℃, and a fractionation pressure of 1.3 MPa. The heavy components are discharged from the bottom of the pre-fractionation tower at a flow rate of 0.05 kg / h, and the gas phase is collected from the top of the pre-fractionation tower and introduced into the pre-fractionation tower top condenser, which is a split condenser. After condensation in the condenser, the liquid phase is refluxed, and the gas phase is introduced into the middle of the light component removal tower at a flow rate of 0.95 kg / h. The reflux ratio of the pre-fractionation tower is 170.

[0083] The light component removal tower is fractionated at a tower bottom temperature of -53.0℃, a tower top temperature of -53.9℃, and a fractionation pressure of 1.2 MPa. The light components are discharged from the top of the light component removal tower at a flow rate of 0.02 kg / h, and the liquid part from the bottom of the light component removal tower is introduced into the light component removal tower bottom reboiler, and part is collected at a flow rate of 0.93 kg / h and introduced into the heavy component removal tower for fractionation. The reflux ratio of the light component removal fractionation tower is 8000.

[0084] The heavy component removal tower is fractionated at a tower bottom temperature of -57.3℃, a tower top temperature of -57.8℃, and a fractionation pressure of 1.0 MPa. The gas phase is collected from the top of the heavy component removal tower and introduced into the heavy component removal tower top condenser, which is a split condenser. After condensation in the condenser, the liquid phase is refluxed, and the gas phase is collected at a flow rate of 0.88 kg / h as electronic grade boron trifluoride via the third filter, introduced into an intermediate storage tank, and compressed by a membrane compressor to obtain high-purity CO bottled product. The liquid part from the bottom of the heavy component removal tower is introduced into the heavy component removal tower bottom reboiler, and part is collected as heavy component impurities at a flow rate of 0.05 kg / h. The reflux ratio of the heavy component removal fractionation tower is 170.

[0085] The purified BF3 gas is detected by an analytical instrument for the content of impurities. Table 2 shows the content of impurities in the purified BF3 obtained in Example 1. The purity of the high-purity BF3 after purification is calculated to be 99.9999%.

[0086] Table 2 Gas impurity content after purification of Example 1

[0087] Component [H2] [N2] O2 CF4 CO2 HF SiF4 SO2 Content / ppm 0.02 0.3 0.1 ＜0.01 0.05 0.1 0.2 ＜0.01

[0088] The overheads of the pre-fractionation column, the light-removing column and the heavy-removing column all use refrigerant as the cold source, the second adsorption column uses the refrigerant from the outlet of the condenser of the fractionation column as the cold source, and the total cold consumption is reduced by 10%.

[0089] The nitrogen tail gas of the first adsorption column and the second adsorption column, the heavy components of the pre-fractionation column and the heavy-removing column, and the light components of the light-removing column all pass through the third adsorption column for tail gas treatment.

[0090] Example 2

[0091] The composition of the crude boron trifluoride gas to be purified is shown in Table 3.

[0092] Table 3 Raw gas phase composition of Example 2

[0093] Component [H2] [N2] O2 CF4 CO2 HF SiF4 SO2 Content / ppm 48 50 30 20 61 23 628 214

[0094] The system for producing electronic-grade boron trifluoride from crude boron trifluoride in this example has a first adsorption column, a second adsorption column and a third adsorption column with a diameter of 300 mm and a height of 3 m. The pre-fractionation column, the light-removing column and the heavy-removing column are packed fractionation columns made of nickel, and the packing is nickel triangular spiral with a diameter of 15 mm. The pre-fractionation column has a height of 7 m and a diameter of 100 mm, the light-removing column has a height of 10 m and a diameter of 150 mm, and the heavy-removing column has a height of 20 m and a diameter of 150 mm. The filtration precision of the first filter, the second filter and the third filter is 0.5 microns.

[0095] The operation method is as follows:

[0096] The first adsorption column and the second adsorption column are heated to 300°C, the first valve and the fourth valve are closed, the second valve and the third valve are opened, and dry nitrogen is introduced for purging at a flow rate of 50 kg / h and a pressure of 1.5 MPa. After purging for 20 h, heating is stopped, nitrogen purging is stopped after the temperature returns to room temperature, the second valve and the third valve are closed, and the system is vacuumed to remove nitrogen.

[0097] The first valve and the fourth valve are opened, the industrial boron trifluoride gas to be purified is depressurized, and then introduced into the first adsorption column and the second adsorption column at a flow rate of 10 kg / h and a pressure of 3.0 MPa through the first filter and the first dust collector for adsorption. The adsorption pressure is 3.0 MPa, the adsorption temperature of the first adsorption column is 35°C, and the adsorption temperature of the second adsorption column is 0°C.

[0098] The crude product after adsorption of boron trifluoride gas is introduced into the middle of the pre-distillation column at a flow rate of 10 kg / h after passing through the second dust remover and the second filter, and is distilled under the conditions of a column bottom temperature of -32.7°C, a column top temperature of -34.0°C, and a distillation pressure of 2.5 MPa. The heavy components are discharged from the bottom of the pre-distillation column at a flow rate of 0.5 kg / h, and the gas phase is taken out from the top of the pre-distillation column and introduced into the pre-distillation column top condenser which is a split condenser. After being condensed by the condenser, the liquid phase is refluxed, and the gas phase is introduced into the middle of the light component removal column at a flow rate of 9.5 kg / h. The reflux ratio of the pre-distillation column is 30.

[0099] The light component removal column is distilled under the conditions of a column bottom temperature of -34.8°C, a column top temperature of -36.0°C, and a distillation pressure of 2.4 MPa. The light components are discharged from the top of the light component removal column at a flow rate of 0.2 kg / h, and the liquid phase is partially introduced into the light component removal column bottom reboiler and partially taken out at a flow rate of 9.3 kg / h and introduced into the heavy component removal column for distillation. The reflux ratio of the light component removal column is 4000.

[0100] The heavy component removal column is distilled under the conditions of a column bottom temperature of -37.2°C, a column top temperature of -37.6°C, and a distillation pressure of 2.2 MPa. The gas phase is taken out from the top of the heavy component removal column and introduced into the heavy component removal column top condenser which is a split condenser. After being condensed by the condenser, the liquid phase is refluxed, and the gas phase is taken out at a flow rate of 8.8 kg / h as electronic grade boron trifluoride after passing through the third filter, introduced into the intermediate storage tank, and compressed by a membrane compressor to obtain high-purity CO bottled product. The liquid phase is partially introduced into the heavy component removal column bottom reboiler and partially taken out as heavy component impurities at a flow rate of 0.5 kg / h. The reflux ratio of the heavy component removal column is 100.

[0101] The purified BF3 gas is detected by an analyzer, and Table 4 shows the impurity content in the purified BF3 obtained in Example 1. The purity of the high-purity BF3 after purification is calculated to be 99.9999%.

[0102] Table 4 Impurity content of the gas after purification in Example 2

[0103]

[0104] The pre-distillation column, the light component removal column, and the heavy component removal column all use refrigerant as a cold source, and the second adsorption column uses the refrigerant at the outlet of the distillation column condenser as a cold source, so that the total cold consumption is reduced by 15%.

[0105] The nitrogen gas tail gas of the first adsorption column and the second adsorption column, the heavy components of the pre-distillation column and the heavy component removal column, and the light components of the light component removal column all pass through the third adsorption column for tail gas treatment.

[0106] Example 3

[0107] The composition of the crude boron trifluoride gas to be purified is shown in Table 5.

[0108] Table 5 Raw gas phase composition of Example 3

[0109]

[0110] The system for producing electronic grade boron trifluoride from crude boron trifluoride in this example comprises a first adsorption tower, a second adsorption tower, and a third adsorption tower, each having a diameter of 100 mm and a height of 1.5 m. The pre-fractionation tower, the light component removal tower, and the heavy component removal tower are packed fractionation towers made of stainless steel, and the packing is stainless steel pressed hole plates having a diameter of 6 mm. The pre-fractionation tower has a height of 4 m and a diameter of 80 mm, the light component removal tower has a height of 6 m and a diameter of 130 mm, and the heavy component removal tower has a height of 12 m and a diameter of 130 mm. The first filter, the second filter, and the third filter have a filtering accuracy of 0.006 microns.

[0111] The operation method is as follows:

[0112] The first adsorption tower and the second adsorption tower are heated to 250°C, the first valve and the fourth valve are closed, the second valve and the third valve are opened, dry nitrogen is introduced for purging, the flow rate is 20 kg / h, the pressure is 1.0 MPa, and the purging time is 15 h. After the temperature returns to room temperature, the nitrogen purging is stopped, the second valve and the third valve are closed, and the system is vacuumed to remove the nitrogen.

[0113] The first valve and the fourth valve are opened, the industrial boron trifluoride gas to be purified is depressurized, and the gas is introduced into the first adsorption tower and the second adsorption tower at a flow rate of 5 kg / h and a pressure of 2.5 MPa through the first filter and the first dust collector. The adsorption pressure is 2.5 MPa, the adsorption temperature of the first adsorption tower is 25°C, and the adsorption temperature of the second adsorption tower is -10°C.

[0114] The crude boron trifluoride gas after adsorption is introduced into the middle of the pre-fractionation tower at a flow rate of 5 kg / h through the second dust collector and the second filter. The tower bottom temperature is -39.9°C, the tower top temperature is -40.2°C, and the distillation pressure is 2.0 MPa. The heavy components are discharged from the tower bottom at a flow rate of 0.1 kg / h, the gas phase is collected from the tower top, introduced into the pre-fractionation tower top condenser, condensed through the condenser, and then returned to the liquid phase. The gas phase is introduced into the middle of the light component removal tower at a flow rate of 4.9 kg / h. The reflux ratio of the pre-fractionation tower is 60.

[0115] The light component removal tower is subjected to distillation under the conditions of a tower bottom temperature of -42.8°C, a tower top temperature of -43.1°C, and a distillation pressure of 1.8 MPa. The light components are discharged from the tower top at a flow rate of 0.1 kg / h, the liquid part of the tower bottom is introduced into the light component removal tower bottom reboiler, and part of the liquid is collected and introduced into the heavy component removal tower for distillation at a flow rate of 4.8 kg / h. The reflux ratio of the light component removal tower is 5000.

[0116] The heavy component removal column is rectified at a column bottom temperature of -45.9°C, a column top temperature of -46.2°C, and a rectification pressure of 1.6 MPa. The gaseous phase of the heavy component removal column top is taken out and enters the heavy component removal column top condenser, which is a partial condenser. After condensation in the condenser, the liquid phase is refluxed, and the gaseous phase is taken out at a flow rate of 4.7 kg / h as electronic grade boron trifluoride after passing through the third filter and enters the intermediate storage tank, and is compressed by the membrane compressor to obtain high-purity CO bottled product. The liquid phase of the heavy component removal column bottom partially enters the heavy component removal column bottom reboiler and partially is taken out as heavy component impurities at a flow rate of 0.1 kg / h. The reflux ratio of the heavy component removal rectification column is 120.

[0117] The purity of the purified BF3 gas is detected by an analyzer, and Table 6 shows the impurity content in the purified BF3 obtained in Example 1. The purity of the high-purity BF3 after purification is calculated to be 99.9998%.

[0118] Table 6 Impurity content of the purified gas in Example 3

[0119] Component [H2] [N2] O2 CF4 CO2 HF SiF4 SO2 Content / ppm 0.05 1.3 0.4 ＜0.01 0.06 0.2 0.2 ＜0.01

[0120] The refrigerant is used as the cold source for the top of the pre-rectification column, the light component removal column, and the heavy component removal column, and the refrigerant at the outlet of the condenser of the rectification column is used as the cold source for the second adsorption column, thereby reducing the total refrigeration consumption by 12%.

[0121] The nitrogen gas tail gas of the first adsorption column and the second adsorption column, the heavy component of the pre-rectification column and the heavy component removal column, and the light component of the light component removal column are all treated by the third adsorption column.

[0122] Example 4

[0123] The composition of the crude boron trifluoride gas to be purified is shown in Table 7.

[0124] Table 7 Composition of the raw gas in Example 4

[0125] Component [H2] [N2] O2 CF4 CO2 HF SiF4 SO2 Content / ppm 68 37 16 15 21 8 912 32

[0126] The system for producing electronic grade boron trifluoride from crude boron trifluoride in this example has a first adsorption column, a second adsorption column, and a third adsorption column with a diameter of 100 mm and a height of 1.5 m. The pre-rectification column, the light component removal column, and the heavy component removal column are stainless steel packed columns with a packing of stainless steel pressed expanded hole plates with a diameter of 6 mm. The pre-rectification column has a height of 6 m and a diameter of 70 mm, the light component removal column has a height of 8 m and a diameter of 80 mm, and the heavy component removal column has a height of 18 m and a diameter of 80 mm. The filtration precision of the first filter, the second filter, and the third filter is 0.003 microns.

[0127] The operation method is as follows:

[0128] Heating the first and second adsorption towers to 250℃, closing the first and fourth valves, opening the second and third valves, and purging with dry nitrogen at a flow rate of 20 kg / h and a pressure of 1.0 MPa for 15 h, then stopping heating, stopping purging with nitrogen after the temperature returns to room temperature, closing the second and third valves, and vacuumizing the system to remove nitrogen.

[0129] Opening the first and fourth valves, reducing the pressure of the industrial boron trifluoride gas to be purified, and feeding the gas into the first and second adsorption towers through the first filter and first dust collector at a flow rate of 5 kg / h and a pressure of 2.5 MPa, the adsorption pressure being 2.5 MPa, the adsorption temperature of the first adsorption tower being 25℃, and the adsorption temperature of the second adsorption tower being -10℃.

[0130] Purifying the crude boron trifluoride gas after adsorption by feeding it into the middle of the pre-fractionation tower through the second dust collector and second filter at a flow rate of 5 kg / h, and fractionating it at a tower bottom temperature of -39.9℃, a tower top temperature of -40.2℃, and a fractionation pressure of 2.0 MPa. Discharging heavy components from the bottom of the pre-fractionation tower at a flow rate of 0.1 kg / h, and feeding the gas phase into the pre-fractionation tower top condenser, which is a split condenser, condensing the gas phase after passing through the condenser, and returning the liquid phase to flow back, and feeding the gas phase into the middle of the light component removal tower at a flow rate of 4.9 kg / h. The reflux ratio of the pre-fractionation tower is 40.

[0131] Fractionating the light component removal tower at a tower bottom temperature of -42.8℃, a tower top temperature of -43.1℃, and a fractionation pressure of 1.8 MPa. Discharging light components from the top of the light component removal tower at a flow rate of 0.1 kg / h, feeding part of the liquid phase from the bottom of the light component removal tower into the light component removal tower bottom reboiler, and feeding part of the liquid phase out at a flow rate of 4.8 kg / h into the heavy component removal tower for fractionation. The reflux ratio of the light component removal fractionation tower is 2000.

[0132] Fractionating the heavy component removal tower at a tower bottom temperature of -45.9℃, a tower top temperature of -46.2℃, and a fractionation pressure of 1.6 MPa. Feeding the gas phase from the top of the heavy component removal tower into the heavy component removal tower top condenser, which is a split condenser, condensing the gas phase after passing through the condenser, and returning the liquid phase to flow back, and feeding the gas phase out at a flow rate of 4.8 kg / h as electronic grade boron trifluoride through the third filter into the intermediate storage tank, and compressing the gas to obtain high purity CO bottled product by a membrane compressor. Feeding part of the liquid phase from the bottom of the heavy component removal tower into the heavy component removal tower bottom reboiler, and feeding part of the liquid phase out as heavy component impurities at a flow rate of 0.1 kg / h. The reflux ratio of the heavy component removal fractionation tower is 40.

[0133] Detecting the impurity content of the purified BF3 gas by an analytical instrument, and Table 8 is the impurity content of the purified BF3 obtained in Example 1 of the present application. The purity of the high purity BF3 after purification is calculated to be 99.9998%.

[0134] Table 8 Gas impurity content after purification of Example 4

[0135] Component [H2] [N2] O2 CF4 CO2 HF SiF4 SO2 Content / ppm 0.05 0.6 0.3 ＜0.01 0.06 0.1 0.2 ＜0.01

[0136] The overheads of the pre-fractionation column, the light-removing column and the heavy-removing column all use refrigerant as the cold source, the second adsorption column uses the refrigerant from the outlet of the fractionation column condenser as the cold source, and the total cold consumption is reduced by 12%.

[0137] The nitrogen gas tail gas of the first adsorption column and the second adsorption column, the heavy components of the pre-fractionation column and the heavy-removing column, and the light components of the light-removing column all pass through the third adsorption column for tail gas treatment.

[0138] Example 5

[0139] The composition of the crude boron trifluoride gas to be purified is shown in Table 9.

[0140] Table 9 Raw gas phase composition of Example 5

[0141] Component [H2] [N2] O2 CF4 CO2 HF SiF4 SO2 Content / ppm 12 40 14 3 17 9 24 13

[0142] The system for producing electronic-grade boron trifluoride from crude boron trifluoride in this embodiment has a first adsorption column, a second adsorption column and a third adsorption column with a diameter of 100 mm and a height of 1.5 m. The pre-fractionation column, the light-removing column and the heavy-removing column are packed fractionation columns made of stainless steel, with packing made of stainless steel pressed expanded hole plates with a diameter of 6 mm. The pre-fractionation column has a height of 5 m and a diameter of 70 mm, the light-removing column has a height of 7 m and a diameter of 110 mm, and the heavy-removing column has a height of 15 m and a diameter of 110 mm. The filtration precision of the first filter, the second filter and the third filter is 0.003 microns.

[0143] The operation method is as follows:

[0144] The first adsorption column and the second adsorption column are heated to 250°C, the first valve and the fourth valve are closed, the second valve and the third valve are opened, and dry nitrogen is introduced for purging at a flow rate of 20 kg / h and a pressure of 1.0 MPa. After purging for 15 h, heating is stopped, nitrogen purging is stopped after the temperature returns to room temperature, the second valve and the third valve are closed, and the system is vacuumed to remove nitrogen.

[0145] The first valve and the fourth valve are opened, the industrial boron trifluoride gas to be purified is depressurized, and then introduced into the first adsorption column and the second adsorption column at a flow rate of 5 kg / h and a pressure of 2.5 MPa through the first filter and the first dust collector for adsorption. The adsorption pressure is 2.5 MPa, the adsorption temperature of the first adsorption column is 25°C, and the adsorption temperature of the second adsorption column is -10°C.

[0146] The crude product after adsorption, boron trifluoride gas, is introduced into the middle of the pre-distillation column at a flow rate of 5 kg / h after passing through the second dust remover and the second filter, and is distilled under the conditions of a column bottom temperature of -39.9 ℃, a column top temperature of -40.2 ℃, and a distillation pressure of 2.0 MPa. The heavy components are discharged from the bottom of the pre-distillation column at a flow rate of 0.1 kg / h, and the gas phase is collected from the top of the pre-distillation column and introduced into the pre-distillation column top condenser, which is a partial condenser. After condensation in the condenser, the liquid phase is refluxed, and the gas phase is introduced into the middle of the light component removal column at a flow rate of 4.9 kg / h. The reflux ratio of the pre-distillation column is 40.

[0147] The light component removal column is distilled under the conditions of a column bottom temperature of -42.8 ℃, a column top temperature of -43.1 ℃, and a distillation pressure of 1.8 MPa. The light components are discharged from the top of the light component removal column at a flow rate of 0.1 kg / h, and the liquid phase is partially introduced into the light component removal column bottom reboiler and partially collected at a flow rate of 4.8 kg / h and introduced into the heavy component removal column for distillation. The reflux ratio of the light component removal column is 4000.

[0148] The heavy component removal column is distilled under the conditions of a column bottom temperature of -45.9 ℃, a column top temperature of -46.2 ℃, and a distillation pressure of 1.6 MPa. The gas phase is collected from the top of the heavy component removal column and introduced into the heavy component removal column top condenser, which is a partial condenser. After condensation in the condenser, the liquid phase is refluxed, and the gas phase is collected at a flow rate of 4.7 kg / h as electronic grade boron trifluoride after passing through the third filter, introduced into the intermediate storage tank, and compressed by a membrane compressor to obtain high-purity CO bottled product. The liquid phase is partially introduced into the heavy component removal column bottom reboiler and partially collected as heavy component impurities at a flow rate of 0.1 kg / h. The reflux ratio of the heavy component removal column is 100.

[0149] The purified BF3 gas is detected by an analytical instrument for the content of impurities, and Table 10 shows the content of impurities in the purified BF3 obtained in Example 1. The purity of the high-purity BF3 after purification is calculated to be 99.9998%.

[0150] Table 10 Content of impurities in the purified gas of Example 5

[0151] Component [H2] [N2] O2 [CAT] CO2 HF SiF4 SO2 Content / ppm 0.02 0.4 0.2 ＜0.01 0.1 0.2 0.1 ＜0.01

[0152] It should be noted that the specific parameters or some reagents in the above examples are specific embodiments or preferred embodiments under the concept of the present application, but are not limited thereto; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present application.

Claims

1. A method for producing electronic grade boron trifluoride, characterized by, The method comprises the steps of: Heating the first adsorption tower and the second adsorption tower, purging with dry nitrogen at 150-300°C for 10-20 hours, closing the heating of the first adsorption tower and the second adsorption tower, and vacuumizing the production system of the electronic-grade boron trifluoride; The crude boron trifluoride is adsorbed by the first adsorption tower and the second adsorption tower through the first filter and the first dust collector, the adsorption pressure of the first adsorption tower and the second adsorption tower is 1.0-1.5 MPa, the temperature of the first adsorption tower is 10-35°C, and the temperature of the second adsorption tower is -20-0°C; After adsorption, the boron trifluoride is purified by the second dust collector and the second filter, then enters the pre-distillation tower, and is further purified by the light-removing tower and the heavy-removing tower; the bottom temperature of the pre-distillation tower is -50.7 to -32.7°C, the top temperature of the pre-distillation tower is -51.5 to -34.0°C, the distillation pressure of the pre-distillation tower is 1.3-2.5 MPa, the bottom temperature of the light-removing tower is -53.0 to -34.8°C, the top temperature of the light-removing tower is -53.9 to -36.0°C, the distillation pressure of the light-removing tower is 1.2-2.4 MPa, the bottom temperature of the heavy-removing tower is -57.3 to -37.2°C, the top temperature of the heavy-removing tower is -57.8 to -37.6°C, and the distillation pressure of the heavy-removing tower is 1.0-2.2 MPa; The purified high-purity boron trifluoride is filtered by the third filter and stored in the intermediate storage tank, and is compressed by the diaphragm compressor to obtain high-purity bottled boron trifluoride; The flow rate of the boron trifluoride to be purified into the pre-distillation tower is 1-10 kg / h, and the heavy component discharge flow rate at the bottom of the tower is 0.05-0.5 kg / h; The flow rate of the boron trifluoride to be purified into the light-removing tower is 0.95-9.5 kg / h, and the light component discharge flow rate at the top of the tower is 0.02-0.2 kg / h; The flow rate of the boron trifluoride to be purified into the heavy-removing tower is 0.93-9.3 kg / h, the heavy component discharge flow rate at the bottom of the tower is 0.05-0.5 kg / h, and the top take-out rate is 0.88-8.8 kg / h; The reflux ratio of the pre-distillation tower is 30-170, the reflux ratio of the light-removing tower is 2000-8000, and the reflux ratio of the heavy-removing tower is 40-180.

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