Process and device for purifying ultra-high purity electronic-grade deuterium gas and recycling heavy water

Abstract

The present application relates to a kind of ultra-high purity electronic grade deuterium gas purification process of water and carbon dioxide, comprising the following steps: S1, evacuation replacement: the purified system is vacuumized, vacuumization makes the internal pressure of purified system drop to-0.098Mpa below, and the rear replacement gas medium is high-purity helium;S2, crude gas is introduced into extraction column, extraction column is set to 20~40 tray number, control crude gas inlet flow is 22~27L / min, control extraction column operating pressure is 0.1~0.4Mpa, operating temperature is-50~‑20 ℃, and the heavy component extractant, heavy water and carbon dioxide are obtained at the bottom of column, and the mixed gas at the top of column is obtained after condensation 99.999% deuterium;S3, the heavy component of extraction column bottom is discharged into rectifying column, and rectifying column is set to 15~30 tray number, control rectifying column operating pressure is normal pressure, and the operating temperature at the top of column is set to 25~40 ℃, and the operating temperature at the bottom of column is 90~100 ℃, and the extractant, heavy water and carbon dioxide are separated;S4, the carbon dioxide obtained after separation of rectifying column is evacuated, and the extractant and heavy water are recycled.

Description

Technical Field

[0001] This invention relates to the field of deuterium purification technology, and in particular to a process and apparatus for purifying ultra-high purity electronic-grade deuterium and recovering heavy water. Background Technology

[0002] Deuterium is a stable isotope of hydrogen. At room temperature, it is a colorless, odorless, and non-toxic flammable gas. It has long been used in nuclear energy, controlled nuclear fusion reactions, deuterated optical fibers, deuterated lubricants, lasers, light bulbs, experimental research, toughening treatment of semiconductor materials, nuclear medicine, and nuclear agriculture. In addition, it also has some important military applications, such as the manufacture of hydrogen bombs, neutron bombs, and DF laser weapons.

[0003] Generally, deuterium gas with a purity of 99.99% to 99.999% is referred to as high-purity deuterium gas. In recent years, with the development of the semiconductor industry, high-purity deuterium gas has gradually become a key specialty gas in the semiconductor manufacturing process, which can be used for chip annealing to improve chip stability. The semiconductor manufacturing process has specific requirements for the CO2 and water content in the required high-purity deuterium gas, with CO2 content required to be below 0.01 ppm and water content below 0.036 ppm.

[0004] Chinese invention patents CN115449818A and CN106342104B respectively disclose an apparatus and method for efficiently preparing high-purity deuterium gas. This method utilizes molecular sieves to purify crude deuterium gas. However, the adsorption of CO2 and moisture by molecular sieves can only achieve a purification depth of 10 ppm, which cannot meet the requirements of semiconductor customers for ultra-high purity deuterium gas. Furthermore, molecular sieves reduce D2 adsorption during purification, resulting in material waste.

[0005] Extractive distillation using methanol as an extractant increases the relative volatility of the original components by introducing methanol before distilling the mixture. This method is widely used in the separation of gases containing carbon dioxide in mixed components. Its advantage lies in its ability to better separate carbon dioxide from deuterium gas, achieving the required level of impurity removal. However, it introduces methanol, a new substance, and wastes heavy water, which is currently very expensive, resulting in significant economic losses. Summary of the Invention

[0006] To address the shortcomings in the deuterium purification process, this invention provides a process and apparatus for purifying ultra-high purity electronic-grade deuterium and recovering heavy water, which can obtain ultra-high purity deuterium gas while simultaneously recovering and reusing heavy water, thus reducing raw material waste.

[0007] The specific technical solution of the process and apparatus for purifying ultra-high purity electronic-grade deuterium and recovering heavy water according to the present invention is as follows:

[0008] A process for purifying ultra-high purity electronic-grade deuterium and recovering heavy water includes the following steps:

[0009] S1. Vacuuming and replacement: The purification system is evacuated to reduce the internal pressure to below -0.098 MPa. The replacement gas medium is then high-purity helium.

[0010] S2. The crude deuterium gas is introduced into the extraction tower. The extraction tower is set with 20 to 40 trays. The inlet flow rate of the crude gas is controlled at 22 to 27 L / min. The operating pressure of the extraction tower is controlled at 0.1 to 0.4 MPa. The operating temperature is -50 to -20℃. The bottom of the tower yields heavy component extractant, heavy water and carbon dioxide. The mixed gas at the top of the tower is condensed to obtain 99.999% deuterium gas.

[0011] S3. The heavy components at the bottom of the extraction column are discharged into the distillation column. The distillation column is set with 15 to 30 trays, the operating pressure of the distillation column is controlled at atmospheric pressure, the operating temperature of the top of the column is set to 25 to 40°C, and the operating temperature of the bottom of the column is 90 to 100°C to separate the extractant, heavy water and carbon dioxide.

[0012] S4. The carbon dioxide obtained after separation in the distillation column is vented, and the extractant and heavy water are recycled and reused.

[0013] Preferably, in step S2, an extractant, which is methanol, is introduced into the extraction tower. The temperature at which methanol is introduced is -50 to -30°C, and the feed molar ratio of methanol to crude deuterium gas is 8:1 to 56:1.

[0014] Preferably, in step S2, before the top gas mixture is condensed, it is pressurized to a pressure of 1.5 to 2.0 MPa.

[0015] Preferably, in step S2, the extractant in the top gas mixture is refluxed and condensed at a temperature of -90°C to -150°C.

[0016] Preferably, in step S2, the content of deuterium in the condensed gas is detected. If the deuterium content is greater than or equal to 99.999%, the inlet flow rate of crude deuterium is increased to 40 L / min.

[0017] Preferably, in step S2, the crude deuterium gas to be purified has a deuterium content of ≥99.7%, a moisture content of ≤3000ppm, and a CO2 content of ≤1000ppm.

[0018] The present invention also provides an apparatus for purifying ultra-high purity electronic-grade deuterium and recovering heavy water, comprising an extraction column and a distillation column. The inlet of the extraction column is connected to a compressor, the top outlet of the extraction column is connected to the inlet of a condenser via a compressor, the outlet of the condenser is connected to the reflux port of the extraction column, the bottom outlet of the extraction column is connected to the inlet of the distillation column, the top of the distillation column is provided with a gas discharge port and a liquid outlet, and the bottom of the distillation column is provided with a liquid drain port.

[0019] Preferably, the extraction column has 20 to 40 trays, and the distillation column has 15 to 30 trays.

[0020] The process and apparatus for purifying ultra-high purity electronic-grade deuterium and recovering heavy water according to the present invention have the following advantages:

[0021] 1. This process can deeply purify crude deuterium gas with a purity of over 99.7%. By precisely controlling the feed ratio of the extractant to the crude deuterium gas, impurities such as carbon dioxide and heavy water, as well as other gases such as nitrogen, oxygen, and carbon monoxide, are effectively removed from the crude product, thereby obtaining ultra-high purity electronic-grade deuterium gas with a purity of over 99.999%, meeting the high-precision electronic field's demand for high-purity gases.

[0022] 2. This method utilizes the low freezing point of methanol to remove it from deuterium gas at low temperatures. Simultaneously, methanol carries heavy water during absorption, which can be completely recovered in subsequent processes through distillation and other methods, improving the yield of heavy water, reducing material waste, and achieving efficient resource utilization.

[0023] 3. This process is simple and clear, comprising three main steps: vacuum displacement, extraction and absorption, and distillation separation. Each step has clearly defined operating parameters and control requirements, making the entire purification process easy to operate and control. Furthermore, this process is highly flexible and adaptable, and can be adjusted and optimized according to different compositions and purity requirements of the raw gas.

[0024] 4. The process and purification equipment have been carefully designed and optimized. The supporting ultra-high purity electronic-grade deuterium purification equipment adopts a combination design of extraction tower and distillation tower, which is compact in structure and occupies a small area. Through reasonable layout and process design, it achieves efficient material separation and energy utilization, and improves the operating efficiency and stability of the entire system. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the ultra-high purity electronic-grade deuterium purification device of the present invention;

[0026] The markings in the diagram are as follows: 1. Compressor 1; 2. Extraction column; 3. Air inlet; 4. Top outlet of the column; 5. Compressor 2; 6. Condenser; 7. Reflux pipe; 8. Bottom outlet of the column; 9. Distillation column; 10. Feed inlet; 11. Vent pipe; 12. Methanol recovery tank; 13. Heavy water recovery tank. Detailed Implementation

[0027] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0028] Example 1

[0029] A process for purifying ultra-high purity electronic-grade deuterium and recovering heavy water includes the following steps:

[0030] S1. Vacuuming and replacement: The purification system is evacuated to reduce the internal pressure to below -0.098 MPa. The replacement gas medium is then high-purity helium.

[0031] S2. The crude deuterium gas is introduced into the extraction tower. The crude deuterium gas contains 99.7% deuterium, 2722.4 ppm moisture, and 30.2 ppm CO2. The impurity content is shown in Table 1.

[0032] The extraction tower is equipped with 40 trays. The extractant, methanol, is introduced into the extraction tower at a temperature of -50℃. The inlet flow rate of the crude gas is controlled at 22L / min, and the feed mass ratio of methanol to deuterium crude gas is 56:1 to ensure that the crude gas is in full contact with the packing of the absorption tower.

[0033] The operating pressure of the extraction tower was controlled at 0.1 MPa, and the operating temperature at -50°C. Ethylene glycol was used as the cooling medium to cool the extraction tower. The operating temperature of the extraction tower was controlled. Heavy extractant, heavy water, and carbon dioxide were obtained at the bottom of the tower. The mixed gas at the top of the tower was condensed to obtain condensate. Before the condensation operation, the mixed gas at the top of the tower was pressurized to a pressure of 2.0 MPa and a condensation temperature of -90°C. The condensate obtained after condensation was returned to the extraction tower. The condensate was sampled through a gas sampling bag, and the deuterium content was found to be 99.999%.

[0034] After passing the test, the inlet rate of crude deuterium gas was increased, and the sample was continuously injected into the absorption tower. The flow rate was increased to 40 L / min. The purity of the collected high-purity deuterium gas reached over 99.999%. The methanol content in the finished product was 0.8 ppm, and the contents of impurities such as water and carbon dioxide were below 0.03 ppm. The deuterium gas yield was 99.99%, and the impurity content is shown in Table 2.

[0035] S3. The heavy components at the bottom of the extraction column are discharged into the distillation column. The operating pressure of the distillation column is controlled at atmospheric pressure, and the operating temperature at the top of the column is set to 40°C. The operating temperature of the reboiler is controlled to 100°C by adjusting the voltage of the heating tile in the reboiler.

[0036] S4. After the heavy components are discharged into the distillation column, the carbon dioxide is first vaporized and discharged from the top of the column. Then, the heavy water and methanol are separated by the distillation operation. The separated methanol is discharged into the methanol recovery tank and can be added back into the absorption column for reuse. The separated heavy water is discharged into the heavy water recovery tank and can be added back into the electrolytic cell for reuse in the preparation of deuterium.

[0037] Table 1

[0038] Content (ppmv) 62.3 47.7 1.8 3.9 30.2 2722.4

[0039] Table 2

[0040] <![CDATA[N2]]> 0.09 CH 0.02 <![CDATA[O2]]> 0.02 <![CDATA[CO2]]> 0.01 <![CDATA[H2]]> 1.8 Moisture 0.03 methanol 0.8

[0041] Example 2

[0042] A process for purifying ultra-high purity electronic-grade deuterium and recovering heavy water includes the following steps:

[0043] S1. Vacuuming and replacement: The purification system is evacuated to reduce the internal pressure to below -0.098 MPa. The replacement gas medium is then high-purity helium.

[0044] S2. The crude deuterium gas is introduced into the extraction tower. The crude deuterium gas contains 99.7% deuterium, 2135.5 ppm moisture, and 33.2 ppm CO2. The impurity content is shown in Table 3.

[0045] The extraction tower is equipped with 30 trays. The extractant, methanol, is introduced into the extraction tower at a temperature of -40℃. The inlet flow rate of the crude gas is controlled at 25L / min, and the feed mass ratio of methanol to deuterium crude gas is 40:1 to ensure that the crude gas is in full contact with the packing of the absorption tower.

[0046] The operating pressure of the extraction tower was controlled at 0.2 MPa, and the operating temperature at -30°C. Ethylene glycol was used as the cooling medium to cool the extraction tower. The operating temperature of the extraction tower was controlled. The bottom of the tower yielded heavy extractant, heavy water, and carbon dioxide. The mixed gas at the top of the tower was condensed to obtain condensate. Before the condensation operation, the mixed gas at the top of the tower was pressurized to 1.5 MPa, and the condensation temperature was -120°C. The condensate obtained after condensation was returned to the extraction tower. The condensate was sampled through a gas sampling bag, and the deuterium content was found to be 99.999%.

[0047] After passing the test, the inlet rate of crude deuterium gas was increased, and the sample was continuously injected into the absorption tower. The flow rate was increased to 40 L / min. The purity of the collected high-purity deuterium gas reached over 99.999%. The methanol content in the finished product was 0.3 ppm, and the contents of impurities such as water and carbon dioxide were below 0.02 ppm. The deuterium gas yield was ≥99.99%, and the impurity content is shown in Table 4.

[0048] S3. The heavy components at the bottom of the extraction column are discharged into the distillation column. The operating pressure of the distillation column is controlled at atmospheric pressure, and the operating temperature at the top of the column is set to 30°C. The operating temperature of the reboiler is controlled to 95°C by adjusting the voltage of the heating tile in the reboiler.

[0049] S4. After the heavy components are discharged into the distillation column, the carbon dioxide is first vaporized and discharged from the top of the column. Then, the heavy water and methanol are separated by the distillation operation. The separated methanol is discharged into the methanol recovery tank and can be added back into the absorption column for reuse. The separated heavy water is discharged into the heavy water recovery tank and can be added back into the electrolytic cell for reuse in the preparation of deuterium.

[0050] Table 3

[0051] Content (ppmv) 20.3 12.5 2.3 4.5 33.2 2135.5

[0052] Table 4

[0053]

[0054]

[0055] Example 3

[0056] A process for purifying ultra-high purity electronic-grade deuterium and recovering heavy water includes the following steps:

[0057] S1. Vacuuming and replacement: The purification system is evacuated to reduce the internal pressure to below -0.098 MPa. The replacement gas medium is then high-purity helium.

[0058] S2. The crude deuterium gas is introduced into the extraction tower. The crude deuterium gas contains 99.7% deuterium, 1563.2 ppm moisture, and 50.2 ppm CO2. The impurity content is shown in Table 5.

[0059] The extraction tower is equipped with 20 trays. The extractant, methanol, is introduced into the extraction tower at a temperature of -30°C. The inlet flow rate of the crude gas is controlled at 27 L / min, and the feed mass ratio of methanol to deuterium crude gas is 8:1 to ensure that the crude gas is in full contact with the packing of the absorption tower.

[0060] The operating pressure of the extraction tower was controlled at 0.4 MPa, and the operating temperature at -20°C. Ethylene glycol was used as the cooling medium to cool the extraction tower. The operating temperature of the extraction tower was controlled. The bottom of the tower yielded heavy component extractant, heavy water, and carbon dioxide. The mixed gas at the top of the tower was condensed to obtain condensate. Before the condensation operation, the mixed gas at the top of the tower was pressurized to a pressure of 2.0 MPa and a condensation temperature of -150°C. The condensate obtained after condensation was returned to the extraction tower. The condensate was sampled through a gas sampling bag, and the deuterium content was found to be 99.999%.

[0061] After passing the test, the inlet rate of crude deuterium gas was increased, and the sample was continuously injected into the absorption tower. The flow rate was increased to 40 L / min. The purity of the collected high-purity deuterium gas reached over 99.999%. The methanol content in the finished product was 0.03 ppm, and the contents of impurities such as water and carbon dioxide were below 0.03 ppm. The deuterium gas yield was ≥99.99%, and the impurity content is shown in Table 6.

[0062] S3. The heavy components at the bottom of the extraction column are discharged into the distillation column. The operating pressure of the distillation column is controlled at atmospheric pressure, and the operating temperature at the top of the column is set to 25°C. The operating temperature of the reboiler is controlled to 90°C by adjusting the voltage of the heating tile in the reboiler.

[0063] S4. After the heavy components are discharged into the distillation column, the carbon dioxide is first vaporized and discharged from the top of the column. Then, the heavy water and methanol are separated by the distillation operation. The separated methanol is discharged into the methanol recovery tank and can be added back into the absorption column for reuse. The separated heavy water is discharged into the heavy water recovery tank and can be added back into the electrolytic cell for reuse in the preparation of deuterium.

[0064] Table 5

[0065] Content (ppmv) 49.8 5.6 1.1 4.2 50.2 1563.2

[0066] Table 6

[0067] <![CDATA[N2]]> 0.01 CH 0.01 <![CDATA[O2]]> 0.02 <![CDATA[CO2]]> 0.03 <![CDATA[H2]]> 1.1 Moisture 0.03 methanol 0.03

[0068] Example 4

[0069] like Figure 1 The diagram shown is a schematic diagram of the device for purifying ultra-high purity electronic-grade deuterium and recovering heavy water according to the present invention.

[0070] An apparatus for purifying ultra-high purity electronic-grade deuterium and recovering heavy water includes an extraction tower 2 and a distillation tower 9. The number of trays in the extraction tower 2 is set to 40. The gas inlet 3 of the extraction tower 2 is connected to a compressor 1. The compressor 1 pressurizes the crude deuterium gas and causes the gas to flow to the extraction tower 2.

[0071] The top outlet 4 of the extraction tower 2 is connected to the compressor 2 5, and the compressor 2 5 is connected to the inlet of the condenser 6. Before the condensation operation, the mixed gas at the top outlet 4 is pressurized by the compressor 2 5 to meet the operating pressure of the condenser 6 for condensing methanol.

[0072] The outlet of condenser 6 is connected to the reflux port of extraction tower 2 through reflux pipe 7. After the mixed gas from the top outlet 4 of the tower is condensed by condenser 6, the condensate is methanol and is returned to extraction tower 2 through reflux pipe 7. The remaining condensate is ultra-high purity electronic-grade deuterium.

[0073] The bottom outlet 8 of the extraction column 2 is connected to the inlet 10 of the distillation column 9. The distillation column 9 has 30 trays. The heavy components discharged from the bottom outlet 8 are separated by distillation. The top of the distillation column 9 is equipped with a gas vent, which is connected to a vent pipe 11. After the heavy components are discharged into the distillation column 9, carbon dioxide is vaporized first, and the separated carbon dioxide is discharged through the top vent pipe 11. The top side of the distillation column 9 is also equipped with an exhaust port, which is connected to a methanol recovery tank 12. After the heavy components are separated by distillation, the separated methanol is discharged into the methanol recovery tank 12. The methanol can be added back into the absorption column for reuse. The bottom of the distillation column 9 is equipped with a liquid drain, which is connected to a heavy water recovery tank 13. After the heavy components are separated by distillation, the separated heavy water is discharged into the heavy water recovery tank 13. The heavy water can be added back into the electrolytic cell for reuse in the preparation of deuterium.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A process for purifying ultra-high purity electronic-grade deuterium and recovering heavy water, characterized in that, Includes the following steps: S1. Vacuuming and replacement: The purification system is evacuated to reduce the internal pressure to below -0.098MPa, and then high-purity helium is used as the replacement gas medium. S2. The crude deuterium gas is introduced into the extraction tower. The extraction tower is set with 20~40 trays, the inlet flow rate of the crude gas is controlled at 22~27 L / min, the operating pressure of the extraction tower is controlled at 0.1~0.4 MPa, and the operating temperature is -50~-20℃. The bottom of the tower yields heavy component extractant, heavy water and carbon dioxide, and the mixed gas at the top of the tower is condensed to obtain 99.999% deuterium gas. S3. The heavy components at the bottom of the extraction column are discharged into the distillation column. The distillation column is set with 15 to 30 trays, the operating pressure of the distillation column is controlled at atmospheric pressure, the operating temperature of the top of the column is set to 25 to 40°C, and the operating temperature of the bottom of the column is 90 to 100°C to separate the extractant, heavy water and carbon dioxide. S4. The carbon dioxide obtained after separation in the distillation column is discharged into the air, and the extractant and heavy water are recovered and reused. In step S2, an extractant, methanol, is introduced into the extraction tower. The temperature of the methanol is -50 to -30°C, and the feed mass ratio of methanol to crude deuterium gas is 8:1 to 56:

1. In step S2, before the top gas mixture is condensed, it is pressurized to a pressure of 1.5~2.0 MPa. In step S2, the extractant in the mixed gas at the top of the column is refluxed by condensation at a temperature of -90℃ to -150℃.

2. The process for purifying ultra-high purity electronic-grade deuterium and recovering heavy water according to claim 1, characterized in that, In step S2, the deuterium content in the condensed gas is detected. If the deuterium content is greater than or equal to 99.999%, the inlet flow rate of the crude deuterium gas is increased to 40 L / min.

3. The process for purifying ultra-high purity electronic-grade deuterium and recovering heavy water according to claim 1, characterized in that, In step S2, the crude deuterium gas to be purified has a deuterium content of ≥99.7%, a moisture content of ≤3000ppm, and a CO2 content of ≤1000ppm.

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