A cascade cryogenic distillation pre-concentration 13 C isotope apparatus

Abstract

This utility model pertains to a cascade low-temperature distillation preconcentration method. 13 A device for C isotopes includes a carbon monoxide feed tank connected to the inlet of a first distillation column. A reboiler is located in the lower part of the first distillation column. A vapor outlet is located on one side of the first distillation column shell, connected to the inlet of a second distillation column via a second condenser channel. The vapor outlet at the top of the second distillation column is connected to a first three-way valve via a fourth condenser channel. The second end of the first three-way valve is connected to a second liquid reflux port at the top of the second distillation column, and the third end is connected to a cascade return port at the bottom of the first distillation column. The liquid outlet at the bottom of the second distillation column is connected to... 13 The C isotope refining section is connected; it features a reasonable structural design, reduces manufacturing and installation difficulty, and achieves energy reduction while producing high-purity CO as a byproduct.

Description

Technical Field

[0001] This utility model pertains to isotopes. 13 In the field of C preparation technology, specifically a cascade low-temperature distillation pre-concentration... 13 A device for C isotopes. Background Technology

[0002] An isotope is a type of atom of the same element that has the same number of protons but different numbers of neutrons. 13 Carbon (C) is an important isotope, stable and non-radioactive, and is widely used as a tracer atom in fields such as medicine, biology, environment, and agriculture. In nature, 13 The natural abundance of C is only 1.1%, and the separation coefficient is extremely low (α = 1.007). Currently, industrial applications in production... 13 Product C can only be produced via low-temperature distillation, using two raw materials: CH4 and CO. Because... 13 The production technology of carbon isotopes is very difficult. Specifically: isotopes 13 The pre-concentration separation of C utilizes the subtle differences in relative molecular weight and boiling point among different forms, employing a low-temperature distillation method. 13 CO in its C form is continuously concentrated in the reactor. 12 CO in its C form is continuously concentrated at the top of the column. Because the boiling points of the two are very similar, separation is extremely difficult and requires a large number of theoretical plates (more than 2,000). Therefore, when using vertical cascade technology, the distillation column is too long (200-300 meters), which poses great difficulties and risks in both equipment manufacturing and installation. Utility Model Content

[0003] To overcome the above shortcomings, this invention provides a cascade low-temperature distillation pre-concentration method. 13 A device for C isotopes is proposed to address the technical problems existing in the prior art.

[0004] The technical solution adopted by this utility model to solve its technical problem is:

[0005] A cascade cryogenic distillation pre-concentration 13 The apparatus for C isotopes includes a carbon monoxide feed tank connected to the inlet of a first distillation column. A reboiler is located in the lower part of the first distillation column. A vapor outlet is located on one side of the first distillation column shell, connected to the inlet of a second distillation column via a second condenser channel. The vapor outlet at the top of the second distillation column is connected to a first three-way valve via a fourth condenser channel. The second end of the first three-way valve is connected to a second liquid reflux port at the top of the second distillation column, and the third end is connected to a cascade return port at the bottom of the first distillation column. The liquid outlet at the bottom of the second distillation column is connected to...13 The C isotope refining section is connected.

[0006] The beneficial effects of this utility model are: This utility model is applicable to 13 Pre-concentration of C isotopes, and can also be applied to 13 The carbon isotope refining section, through the above-described setup, can achieve a cascade configuration of two distillation columns, thereby significantly reducing the traditional... 13 The height of each carbon isotope distillation column can be controlled within 30m. Specifically, in this invention, the gas phase is taken from the bottom of the first distillation column, powered by the reboiler of the first distillation column, and condensed into a liquid phase by the condenser before being fed into the second distillation column. The gas phase at the top of the second distillation column enters the condenser through the pressure difference and liquefies. It then returns to the bottom of the first distillation column by its own gravity, realizing cascade feeding of the first distillation column. This ensures that the pressure of the two distillation columns remains consistent, eliminating the pressure difference. Furthermore, the above structure reduces the material transport between the first and second distillation columns, reducing the return material by more than 90%, thereby significantly improving the distillation efficiency of the columns and greatly reducing both power consumption and energy consumption.

[0007] Preferably, the vapor outlet at the top of the first distillation column is connected to the first liquid reflux port at the top of the reboiler of the first distillation column via the first condenser channel of the condenser.

[0008] Preferably, the inner wall of the first distillation column located below the first liquid reflux port is provided with a liquid overflow weir, and the inner wall of the first distillation column corresponding to the liquid overflow weir is provided with a liquid high-purity CO discharge port, which is connected to a high-purity CO storage tank through a pipeline.

[0009] This utility model also includes a circulating gas compressor. The outlet of the circulating gas compressor is connected to the inlet of the first distillation column reboiler and the second distillation column reboiler respectively through a second tee. The outlets of the first distillation column reboiler and the second distillation column reboiler are connected to the third condenser channel of the condenser respectively through a third tee. A circulating gas replenishment pipe with a replenishment valve is provided between the third condenser channel and the inlet of the circulating gas compressor.

[0010] Preferably, a first regulating valve is provided between the carbon monoxide feed tank and the inlet of the first distillation column, a second regulating valve is provided between the gas phase outlet and the second channel of the condenser, a third regulating valve is provided between the third end of the first tee and the cascade return port, and the liquid phase outlet at the bottom of the second distillation column is connected to... 13 A fifth regulating valve is installed between the C isotope refining sections.

[0011] Preferably, a fourth regulating valve is provided between the first channel of the condenser and the first liquid phase reflux port.

[0012] Preferably, a sixth regulating valve is provided between the liquid phase high-purity CO discharge port and the high-purity CO storage tank.

[0013] A cascade cryogenic distillation preconcentrator was prepared according to the above scheme. 13 The C isotope device includes a first distillation column reboiler located within the first distillation column. Vaporization in the first reboiler serves as the driving force, preferentially transporting the vaporized gas to a condenser for liquefaction. The liquefied gas is then fed into a second distillation column. The vapor phase from the top of the second distillation column enters the condenser through a pressure difference, liquefies, and returns to the bottom of the first distillation column by gravity, achieving cascade feeding of the first distillation column. This ensures consistent pressure between the two columns, eliminating pressure differences. Furthermore, this structure reduces material transport between the first and second distillation columns, reducing backflow by over 90%, significantly improving distillation efficiency and reducing both power and energy consumption. Additionally, the device includes a liquid overflow weir in the upper middle part of the first distillation column, enabling timely collection of high-purity CO liquid (containing...) 13 The liquid with low C content is removed, thereby reducing the amount of gas-liquid phase distribution on the tray below the overflow weir, so as to significantly reduce the distillation load of the first rectification while producing high-purity CO as a by-product; it has the characteristics of reasonable structural design, reduced manufacturing and installation difficulty, and reduced energy consumption while achieving high-purity CO as a by-product. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the structure of this utility model.

[0016] In the diagram: 1. Carbon monoxide feed tank; 2. First distillation column; 3. Second distillation column; 4. Reboiler of the first distillation column; 5. Reboiler of the second distillation column; 6. Vapor outlet; 7. Condenser; 8. First condenser channel; 9. Second condenser channel; 10. Third condenser channel; 11. Fourth condenser channel; 12. Circulating gas compressor; 13. First liquid reflux port; 14. Second liquid reflux port; 15. Cascade return port; 16. 13C isotope refining section; 17. Liquid overflow weir; 18. High-purity liquid CO discharge port; 19. High-purity CO storage tank; 20. First tee; 21. Second tee; 22. Third tee; 23. Gas supply valve; 24. First regulating valve; 25. Second regulating valve; 26. Third regulating valve; 27. Fourth regulating valve; 28. Fifth regulating valve; 29. ​​Sixth regulating valve. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0018] The following is in conjunction with the appendix Figure 1 This application provides a further detailed description of the present invention, which is a cascade low-temperature distillation pre-concentration method. 13 The C isotope apparatus includes a carbon monoxide feed tank 1, which is connected to the inlet of a first distillation column 2. A reboiler 4 is located in the lower part of the first distillation column 2. A vapor outlet 6 is located on one side of the reboiler 4 on the shell of the first distillation column 2. The vapor outlet 6 is connected to the inlet of a second distillation column 3 via a second condenser channel 9 of a condenser 7. The vapor outlet at the top of the second distillation column 3 is connected to a first three-way valve 20 via a fourth condenser channel 11 of the condenser 7. The second end of the first three-way valve 20 is connected to a second liquid reflux port 14 at the top of the second distillation column 3, and the third end of the first three-way valve 20 is connected to a cascade return port 15 at the bottom of the first distillation column 2. The liquid outlet at the bottom of the second distillation column 3 is connected to... 13 C isotope refining section 16 is connected. This utility model is applicable to isotopes. 13 Pre-concentration of C can also be applied to isotopes. 13 The refining section of column C; this utility model can replace the traditional single column with two distillation columns connected in series, thereby reducing the difficulty of manufacturing and installation. Furthermore, the gas phase is taken from the bottom of the first distillation column 2, powered by the reboiler 4 of the first distillation column, and condensed into liquid phase by the condenser 7 before being transported to the second distillation column 3 to complete the feeding. The gas phase at the top of the second distillation column 3 enters the condenser through the pressure difference and liquefies. It returns to the bottom of the first distillation column 2 by its own gravity, realizing the cascade feeding of the first distillation column 2, so that the pressure of the two distillation columns is kept consistent and there is no pressure difference. Furthermore, the above structure reduces the material transportation between the first distillation column 2 and the second distillation column 3, and the return material can be reduced by more than 90%, thereby greatly improving the distillation efficiency of the distillation column and significantly reducing both power consumption and energy consumption.

[0019] Furthermore, the vapor outlet at the top of the first distillation column 2 is connected to the first liquid reflux port 13 at the top of the reboiler 4 of the first distillation column via the first condenser channel 8 of the condenser 7.

[0020] Furthermore, a liquid overflow weir 17 is provided on the inner wall of the first distillation column 2 located below the first liquid reflux port 13. A high-purity liquid CO outlet 18 is provided on the inner wall of the first distillation column 2 corresponding to the lower part of the liquid overflow weir 17. The high-purity liquid CO outlet 18 is connected to the high-purity CO storage tank 19 via a pipeline. This arrangement ensures that the upper middle part of the first distillation column 2 has a liquid overflow weir 17, which can promptly discharge high-purity CO liquid (containing...) 13 The liquid with low C content is removed, thereby reducing the amount of gas-liquid phase distribution on the tray below the overflow weir 17, so as to achieve the characteristic of significantly reducing the load of the first distillation and distillation 2 while producing high-purity CO as a by-product.

[0021] This invention also includes a circulating gas compressor 12. The outlet of the circulating gas compressor 12 is connected to the inlets of the first distillation column reboiler 4 and the second distillation column reboiler 5 via a second three-way valve 21. The outlets of the first distillation column reboiler 4 and the second distillation column reboiler 5 are connected to the third condenser channel 10 of the condenser 7 via a third three-way valve 22. A circulating gas makeup pipe with a makeup gas valve 23 is provided between the third condenser channel 10 and the inlet of the circulating gas compressor 12. The third condenser channel 10 in this invention corresponds to the shell side of the condenser 7. This invention uses the circulating gas compressor 12 for pressurization to provide a heat source for the first distillation column reboiler 4 and the second distillation column reboiler 5. The circulating gas can use nitrogen circulation refrigeration instead of the current liquid nitrogen refrigeration. The above method can reduce liquid nitrogen consumption and energy consumption.

[0022] Furthermore, a first regulating valve 24 is provided between the carbon monoxide feed tank 1 and the inlet of the first distillation column 2; a second regulating valve 25 is provided between the gas phase outlet 6 and the second channel 9 of the condenser; a third regulating valve 26 is provided between the third end of the first three-way valve 20 and the cascade return port 15; and the liquid phase outlet at the bottom of the second distillation column 3 is connected to... 13 A fifth regulating valve 28 is provided between the C isotope refining section 16 and the C isotope refining section 16.

[0023] Furthermore, a fourth regulating valve 27 is provided between the first channel 8 of the condenser and the first liquid phase reflux port 13.

[0024] Furthermore, a sixth regulating valve 29 is provided between the liquid high-purity CO discharge port 18 and the high-purity CO storage tank 19. This configuration allows for control of the liquid high-purity CO production, thereby enabling the regulated production of both products according to demand.

[0025] The working principle of this utility model is as follows: Step 1: The raw material gas in the carbon monoxide raw material tank 1 enters the first distillation column 2 through the first regulating valve 24; the raw material gas consists of nitrogen, oxygen, methane, and carbon monoxide; the temperature of the raw material gas is -188℃, the pressure is 0.2 MPa, and the flow rate is 120 Nm³. 3 / h, vapor phase fraction 0, carbon monoxide molar fraction ≥99.9%; the operating pressure of the T1 distillation column is 0.15 MPaG; Step 2: The raw material entering the first distillation column 2 in Step 1 is purified by distillation. The vapor phase after the first distillation purification flows back into the first distillation column 2 through the vapor phase outlet at the top of the first distillation column 2, the first condenser channel 8 of the condenser 7, and the first liquid phase reflux port 13. A portion of the reflux liquid enters the liquid overflow weir 17 and enters the high-purity CO storage tank 19 through the high-purity CO discharge port 18, thereby obtaining high-purity CO; the vapor phase temperature at the vapor phase outlet at the top of the first distillation column 2 is -185~-187℃, CO molar fraction: 99.999%; the high-purity CO temperature entering the high-purity CO storage tank 19 is -188℃, and the flow rate is 105.2 Nm³. 3 / h, CO purity ≥99.999%, gas phase fraction: 0; Step 3: The gas phase from the gas outlet 6 of the first distillation column 2 is condensed through the second condenser channel 9 of the condenser 7 and then enters the second distillation column 3 for distillation; The material temperature entering the second distillation column 3: -189℃, gas phase fraction: 0; The operating pressure of the second distillation column 3: 0.15 MPaG; Step 4: The second distillation column 3 performs distillation on the material to achieve pre-concentration, separation and purification. The pre-concentrated and purified liquid product enters the liquid phase outlet at the bottom of the second distillation column 3. 13 Within the C isotope refining section 16; the liquid phase temperature at the bottom liquid outlet of the second distillation column 3 is -186℃, and the flow rate is 14.8 Nm³. 3 / h、 13C abundance ≥ 10%; Step 5: The vapor phase after the material is distilled in the second distillation column 3 is condensed into liquid phase through the vapor phase outlet at the top of the second distillation column 3 and the fourth condenser channel 11 of the condenser 7. Part of the liquid phase flows back into the second distillation column 3 through the second liquid phase reflux port 14 at the top of the second distillation column 3, and the other part of the liquid phase enters the first distillation column 2 through the cascade return port 15 at the bottom of the first distillation column 2, realizing the cascade distillation of the first distillation column 2 and the second distillation column 3. The vapor phase outlet temperature at the top of the second distillation column 3 is: -187℃~-188℃; Step 6: The circulating gas compressor 12 compresses the circulating gas and sends it into the reboiler 4 of the first distillation column and the reboiler 5 of the second distillation column, providing the required heat for the reboiling of the first distillation column 2 and the second distillation column 3 respectively. After the circulating gas releases its own heat, it changes from a gaseous state to a liquid state. The liquid in the first distillation column 2 and the second distillation column 3 enters the third channel 10 of the condenser 7 to provide cooling for the first distillation column 2 and the second distillation column 3 respectively. After providing cooling, the liquid absorbs heat and completely vaporizes before returning to the circulating compressor 12 for the next cycle. The components of the circulating gas are nitrogen, hydrogen, and argon, with a nitrogen mole fraction of 99.99%. The liquid temperature at the outlet of the reboiler 4 and the reboiler 5 of the first distillation column is -186℃, and the gas phase fraction is 0%. The gas temperature at the outlet of the third channel 10 of the condenser is -191 to 194℃, and the gas phase fraction is 100%. The above-mentioned circulating refrigeration technology can save more than 65% of liquid nitrogen consumption and more than 25% of electricity consumption. Through the above method, high-purity carbon monoxide products with a purity ≥5N can be obtained simultaneously, and more than 10% of the product can be obtained. 13 C pre-concentrated product; compared with traditional production processes, this invention has the following advantages: 1. It can achieve 13 The pre-concentration of C isotopes and the production of high-purity carbon monoxide significantly reduce the production cost of CO (CO purification process can produce byproducts). 13 C. Pre-concentrated products (higher added value); 2. High-pressure nitrogen heat pump circulation replaces the traditional electric heating + liquid nitrogen heating and cooling mode, greatly reducing... 13 C. Energy consumption (liquid nitrogen and electricity) during production and process; 3. Adopting a dual-tower cascade distillation, the gas phase taken from the bottom of the first distillation tower 2 (reliquefied) enters the top of the second distillation tower 3, while the gas phase at the top of the second distillation tower 3 returns to the bottom of the first distillation tower 2, reducing the amount of return material in the cascade process, thereby reducing the distillation load and achieving energy saving of the unit.

[0026] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. A cascade cryogenic distillation pre-concentration method 13 The apparatus for C isotopes, comprising a carbon monoxide feed tank (1), is characterized in that: The carbon monoxide feed tank (1) is connected to the inlet of the first distillation column (2). The lower part of the first distillation column (2) is equipped with a first distillation column reboiler (4). A gas phase outlet (6) is opened on the shell of the first distillation column (2) on one side of the first distillation column reboiler (4). The gas phase outlet (6) is connected to the inlet of the second distillation column (3) through the second condenser channel (9) of the condenser (7). The gas phase outlet at the top of the second distillation column (3) is connected to the first tee (20) through the fourth condenser channel (11) of the condenser (7). The second end of the first tee (20) is connected to the second liquid phase reflux port (14) at the top of the second distillation column (3). The third end of the first tee (20) is connected to the cascade return port (15) at the bottom of the first distillation column (2). The liquid phase outlet at the bottom of the second distillation column (3) and 13 The C isotope refining section (16) is connected.

2. The cascade low-temperature distillation pre-concentration method according to claim 1 13 The device for C isotopes is characterized by: The gas phase outlet at the top of the first distillation column (2) is connected to the first liquid phase reflux port (13) at the top of the reboiler (4) of the first distillation column via the first condenser channel (8) of the condenser (7).

3. A cascade low-temperature distillation pre-concentration method according to claim 2 13 The device for C isotopes is characterized by: The first distillation column (2) located below the first liquid reflux port (13) has a liquid overflow weir (17) on its inner wall. The first distillation column (2) located below the liquid overflow weir (17) has a liquid high-purity CO discharge port (18) on its inner wall. The liquid high-purity CO discharge port (18) is connected to the high-purity CO storage tank (19) through a pipeline.

4. A cascade low-temperature distillation pre-concentration method according to claim 1 13 The device for C isotopes is characterized by: It also includes a circulating gas compressor (12). The outlet of the circulating gas compressor (12) is connected to the inlet of the first distillation column reboiler (4) and the second distillation column reboiler (5) respectively through the second tee (21). The outlets of the first distillation column reboiler (4) and the second distillation column reboiler (5) are connected to the condenser third channel (10) of the condenser (7) through the third tee (22). A circulating gas makeup pipeline with a makeup gas valve (23) is provided between the condenser third channel (10) and the inlet of the circulating gas compressor (12).

5. A cascade low-temperature distillation pre-concentration method according to claim 1 13 The device for C isotopes is characterized by: A first regulating valve (24) is provided between the carbon monoxide feed tank (1) and the inlet of the first distillation column (2); a second regulating valve (25) is provided between the gas phase outlet (6) and the second channel (9) of the condenser; a third regulating valve (26) is provided between the third end of the first tee (20) and the cascade return port (15); and the liquid phase outlet at the bottom of the second distillation column (3) is connected to... 13 A fifth regulating valve (28) is provided between the C isotope refining section (16).

6. A cascade low-temperature distillation pre-concentration method according to claim 2 13 The device for C isotopes is characterized by: A fourth regulating valve (27) is provided between the first channel (8) of the condenser and the first liquid phase reflux port (13).

7. A cascade low-temperature distillation pre-concentration method according to claim 3 13 The device for C isotopes is characterized by: A sixth regulating valve (29) is provided between the liquid phase high-purity CO discharge port (18) and the high-purity CO storage tank (19).

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