A step-by-step distillation method 13 C isotope abundance method

Abstract

The invention belongs to the technical field of isotopes and provides a step-by-step distillation method for improving 13 The method of measuring the abundance of C isotopes solves the problem of low production capacity of isotope products. The method removes impurities from the raw material CO to obtain an intermediate gas; the intermediate gas is sequentially subjected to primary distillation, secondary distillation, scrambling recombination, low-temperature impurity removal, tertiary distillation and quaternary distillation to complete the treatment. By removing impurities from the raw material CO, most of the impurities in the raw material gas can be removed to meet industrial requirements; then, after primary distillation and secondary distillation, a gas rich in C is obtained. 13 C component gas, scrambles and reorganizes the gas to produce more 13 C 16 O components; high abundance is obtained by low temperature impurity removal in the next step 13 C isotope gas; the abundance is further increased through subsequent two-stage distillation to obtain the final product. The method provided by the present invention is simple and can efficiently obtain an abundance of 99.999% 13 C gas has a good application prospect.

Description

Technical Field

[0001] The present invention relates to the field of isotope technology, in particular to a method for improving 13 C isotope abundance method. Background Art

[0002] The application of stable isotopes is becoming more and more widespread, and the separation methods include thermal diffusion, gas diffusion, centrifugal separation, laser separation, chemical exchange, ion exchange and distillation. 13 C. 18 O. 15 N. 10 B is mostly obtained by low temperature distillation of CO, NO, and BF3. 12 CO / 13 The ideal separation coefficient of CO is 1.01, but in reality it is mostly less than 1.008. 13 CO enrichment up to 99% 13 CO, generally requires 3000 theoretical plates, so the isotope separation cascade has a very long length. At the same time, due to the use of random packing, the tower diameter is generally less than 100mm. To expand the production scale, a multi-tube tower must be used. This makes the actual production device quite difficult to install. In the prior art, there are stable isotopes. 13 In 1947, Eastman Kodak Company in the United States adopted the highly toxic HCN / NaCN chemical exchange method (Clyde A. Hutchison, David W. Stewart, Harold C. Urey, the concentration of 13 C, Journal of Chemical Physics, Vol. 8, 1940, 532-537) to conduct semi-industrial production of 65%. 13 C, and was later ordered to close. In the 1960s, the United States used CH4 thermal diffusion to produce 13C (WM Rutherford, JM Keller, Preparation of highly enriched carbon-13 by thermal diffusion of methane, the journal of chemical physics, Vol. 44, No. 2, 1966, 723); because the method has a small production capacity and consumes a lot of electricity, it has not been further developed. Los Alamos Laboratory in the United States (BB Mclnteer, isotope separation by distillation: design of a carbon-13 plant, separation science and technology, vol. 15, No. 3, 1980, 491-508) established a plant with an annual output of 8kg / a 99% 13C (design capacity of 20kg / a), namely the Cola-Colita device in 1978. The main tower consists of two sections. The first stage consists of 6 multi-tube towers with a diameter of 5 cm and a length of 100 m in parallel. The second stage consists of a tower with a length of 100 m and a diameter of 5 cm. The tower is filled with random packing, and the two stages are vertically connected, with a total length of 200 m. The characteristic of this method is the use of vertical cascade, which is easy to implement. The disadvantage is that a large number of tubes with very small diameters are required to be arranged in parallel to increase the output. The distillation tower is particularly long and has high site requirements. The abundance of direct distillation 13C products can only reach 81.9%. U.S. Patents US4029559, US4941956, and US5827405 reported the use of laser separation. 13 C isotopes, but no industrial applications have been seen. Although the laser method is favored by many experts, it has extremely high energy consumption and the technology is not yet mature. Tokyo Gas Co. of Japan established a low-temperature distillation pilot plant with methane as the medium from 1988 to 1999 (Ito Kazuo, On the development of methane carbon isotope separation technology using low-temperature precision distillation, Petrotech, Vol.16, No.8, 1993, P727-729). The device consists of a raw material pre-treatment section, 13 CH4 concentration section and 12 The CH4 concentration section consists of three parts. 13 The CH4 concentration section consists of three 30-meter-high cascades, of which the first stage consists of 7 towers in parallel and uses self-developed fillers. The designed theoretical plate number of the first tower is 1,000, the second tower is 1,200, and the third tower is 1,000. 12 The theoretical number of plates of CH4 concentration tower is 1300. 13C low-temperature distillation production technology has the disadvantages of too high equipment, complex structure, high cold energy consumption, poor reliability of transmission equipment, and difficulty in achieving 99% isotope product, resulting in high production costs and low production capacity. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects in the prior art and provide a step-by-step distillation method. 13 C isotope abundance method.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a step-by-step distillation method for improving 13 The method for determining C isotope abundance comprises the following steps:

[0006] (1) removing impurities from the raw material CO to obtain an intermediate gas;

[0007] (2) The intermediate gas is sequentially subjected to primary distillation, secondary distillation, scrambling recombination, low-temperature impurity removal, tertiary distillation and quaternary distillation to complete the treatment.

[0008] Preferably, the impurity removal treatment in step (1) is low-temperature impurity removal, room-temperature adsorption, heavy impurity removal, light impurity removal and secondary low-temperature impurity removal performed in sequence;

[0009] The pressure of the low temperature impurity removal is 280-320 psia and the temperature is 180-190K.

[0010] Preferably, the pressure of the room temperature adsorption is 200-220psia and the temperature is 270-280K;

[0011] The heavy impurity removal has a pressure of 200-220 psia, a temperature of 110-120 K, and a gas flow rate of 4-5 kg / h.

[0012] Preferably, the light impurity removal pressure is 110-120psia, the temperature is 100-120K, and the gas flow rate is 3-4kg / h;

[0013] The pressure of the secondary low-temperature impurity removal is 280-320 psia and the temperature is 180-190K.

[0014] Preferably, the top temperature of the first-level distillation in step (2) is 90-95K, the top pressure is 19-20psia, the temperature in the tower is 170-190K, the pressure in the tower is 36-37psia, the bottom temperature is 295-305K, the bottom pressure is 41-42psia, and the gas flow rate is 290-300g / h.

[0015] Preferably, the top temperature of the secondary distillation in step (2) is 90-95K, the top pressure is 20-21psia, the temperature in the tower is 140-160K, the pressure in the tower is 32.5-33.5psia, the bottom temperature is 140-160K, the bottom pressure is 41-42psia, and the gas flow rate is 70-75g / h.

[0016] Preferably, the temperature of the scrambling recombination in step (2) is 350-750° C., and the gas flow rate is 25-26 Kg / Hr.

[0017] Preferably, the pressure of the low-temperature impurity removal in step (2) is 250-260 psia, the temperature is 200-210K, and the gas flow rate is 6-6.1 Kg / Hr.

[0018] Preferably, the top temperature of the tertiary distillation in step (2) is 90-100K, the top pressure is 35-36psia, the temperature in the tower is 165-170K, the pressure in the tower is 50-55psia, the bottom temperature is 145-155K, the bottom pressure is 62-63psia, and the gas flow rate is 35-40g / h.

[0019] Preferably, the top temperature of the quaternary distillation in step (2) is 100-105K, the top pressure is 23.5-24.5psia, the temperature in the tower is 135-140K, the pressure in the tower is 24.5-25psia, the bottom temperature is 190-195K, the bottom pressure is 31.5-32psia, and the gas flow rate is 20-30g / h.

[0020] The present invention provides a step-by-step distillation method for improving 13 The method for measuring the isotope abundance of C isotope, wherein the raw material CO is subjected to impurity removal treatment to obtain an intermediate gas; the intermediate gas is subjected to primary distillation, secondary distillation, scrambling recombination, low-temperature impurity removal, tertiary distillation and quaternary distillation in sequence to complete the treatment. The method removes most of the impurities in the raw material CO by removing impurities, which can meet industrial requirements; and then the intermediate gas is subjected to primary distillation and secondary distillation to obtain a carbon-rich 13 C component gas, but some of the remaining 12 C component and 16 O combines into molecules and exists in the gas; in order to further increase the abundance of 13C, the gas is scrambled and reorganized. 12 C 16 O molecules open, 13 C and 18 O is separated and then 16 O combines into molecules, producing more 13 C 16O components; CO2 and N2 in the mixed gas are further removed by low-temperature impurity removal in the next step to obtain high-abundance 13 C isotope gas; the abundance is further increased through subsequent two-stage distillation to obtain the final product 13 C. The method provided by the present invention is simple in process, has low process and equipment requirements, and can efficiently obtain high abundance 13 C gas has a good application prospect. DETAILED DESCRIPTION

[0021] The present invention provides a step-by-step distillation method for improving 13 The method for determining C isotope abundance comprises the following steps:

[0022] (1) removing impurities from the raw material CO to obtain an intermediate gas;

[0023] (2) The intermediate gas is sequentially subjected to primary distillation, secondary distillation, scrambling recombination, low-temperature impurity removal, tertiary distillation and quaternary distillation to complete the treatment.

[0024] In the present invention, the impurity removal treatment in step (1) is low-temperature impurity removal, room-temperature adsorption, heavy impurity removal, light impurity removal and secondary low-temperature impurity removal performed in sequence.

[0025] In the present invention, the low-temperature impurity removal is carried out in a low-temperature cold trap.

[0026] In the present invention, the pressure of the low-temperature impurity removal is preferably 280-320 psia, more preferably 285-315 psia, more preferably 290-310 psia; the temperature is preferably 180-190K, more preferably 182-188K, more preferably 184-186K.

[0027] In the present invention, the room temperature adsorption is carried out in a room temperature adsorber.

[0028] In the present invention, the pressure of the room temperature adsorption is preferably 200-220 psia, more preferably 205-215 psia, more preferably 208-212 psia; the temperature is preferably 270-280K, more preferably 272-278K, more preferably 274-276K.

[0029] In the present invention, the heavy impurity removal is carried out in a deweighting tower.

[0030] In the present invention, the pressure of the heavy impurity removal is preferably 200-220 psia, further preferably 205-215 psia, more preferably 208-212 psia; the temperature is preferably 110-120K, further preferably 112-118K, more preferably 114-116K; the gas flow rate is preferably 4-5 kg / h, further preferably 4.2-4.8 kg / h, more preferably 4.4-4.6 kg / h.

[0031] In the present invention, most of the nitrogen, methane and other components in the raw gas are removed through heavy impurity removal.

[0032] In the present invention, the light impurity removal is carried out in a light impurity removal tower.

[0033] In the present invention, the pressure of the light impurity removal is preferably 110-120 psia, more preferably 112-118 psia, more preferably 114-116 psia; the temperature is preferably 100-120K, more preferably 105-115K, more preferably 108-112K; the gas flow rate is preferably 3-4 kg / h, more preferably 3.2-3.8 kg / h, more preferably 3.4-3.6 kg / h.

[0034] In the present invention, most of the oxygen in the feedstock is removed by light impurity removal.

[0035] In the present invention, the gas after light impurity removal is compressed and stored by a compressor, and then distilled after the next step of impurity removal.

[0036] In the present invention, the secondary low-temperature impurity removal is carried out in a low-temperature cold trap.

[0037] In the present invention, the pressure of the secondary low-temperature impurity removal is preferably 280-320 psia, more preferably 285-315 psia, more preferably 290-310 psia; the temperature is preferably 180-190K, more preferably 182-188K, more preferably 184-186K.

[0038] In the present invention, the primary distillation, the secondary distillation, the tertiary distillation and the quaternary distillation are respectively operated in distillation towers, in which cascade reaction columns are connected in parallel, and the distillation towers are connected in series.

[0039] In the present invention, the diameter of the distillation tower is preferably 110 to 120 cm, more preferably 112 to 118 cm, and even more preferably 114 to 116 cm.

[0040] In the present invention, a condenser is provided at the top of the distillation tower, a reboiler is connected to the bottom of the tower, the bottom of the front-stage distillation tower is connected to the middle feed port of the secondary distillation tower through a cryogenic pump device, and the top of the distillation tower is recovered through a gas recovery device, or returned to the primary distillation tower through a pressure difference.

[0041] In the present invention, each stage of the distillation tower is connected by a cryogenic pump, which plays a role in removing impurities. The pressure of the impurities removal is preferably 280-320 psia, more preferably 285-315 psia, and more preferably 290-310 psia; the temperature is preferably 180-190K, more preferably 182-188K, and more preferably 184-186K.

[0042] In the present invention, the tower top temperature of the primary distillation in step (2) is preferably 90-95K, more preferably 91-94K, more preferably 92-93K; the tower top pressure is preferably 19-20psia, more preferably 19.2-19.8psia, more preferably 19.4-19.6psia; the tower temperature is preferably 170-190K, more preferably 175-185K, more preferably 178-182K; the tower pressure is preferably 36-37psia, more preferably 3 6.2~36.8psia, more preferably 36.4~36.6psia; the bottom temperature is preferably 295~305K, further preferably 296~304K, more preferably 298~302K; the bottom pressure is preferably 41~42psia, further preferably 41.2~41.8psia, more preferably 41.4~41.6psia; the gas flow rate is preferably 290~300g / h, further preferably 292~298g / h, more preferably 294~296g / h.

[0043] In the present invention, the primary distillation is carried out in a primary distillation tower, and the number of cascade reaction columns of the primary distillation tower is preferably 2 to 30, more preferably 4 to 26, and even more preferably 8 to 20.

[0044] In the present invention, after the first-stage distillation is completed, the isotope gas is discharged through the top of the distillation tower, and the heavy component gas is enriched at the bottom of the distillation tower and sent to the second-stage distillation tower through the gas phase pipeline.

[0045] In the present invention, the tower top temperature of the secondary distillation in step (2) is preferably 90-95K, more preferably 91-94K, more preferably 92-93K; the tower top pressure is preferably 20-21psia, more preferably 20.2-20.8psia, more preferably 20.4-20.6psia; the tower temperature is preferably 140-160K, more preferably 145-155K, more preferably 148-152K; the tower pressure is preferably 32.5-33.5psia, more preferably 32.5-33.5psia. The tower bottom temperature is preferably 140-160K, further preferably 145-155K, more preferably 148-152K; the tower bottom pressure is preferably 41-42psia, further preferably 41.2-41.8psia, more preferably 41.4-41.6psia; the gas flow rate is preferably 70-75g / h, further preferably 71-74g / h, more preferably 72-73g / h.

[0046] In the present invention, the secondary distillation is carried out in a secondary distillation tower, and the number of cascade reaction columns of the secondary distillation tower is preferably 2 to 10, more preferably 4 to 8, and even more preferably 5 to 7.

[0047] In the present invention, after the secondary distillation is completed, the isotope gas is discharged through the top of the distillation tower, and the heavy component gas is enriched at the bottom of the distillation tower and transported through the gas phase pipeline.

[0048] In the present invention, the product obtained by the secondary distillation first enters a cryogenic pump and then undergoes scrambling recombination and low-temperature impurity removal.

[0049] In the present invention, the temperature of the scrambling recombination in step (2) is preferably 350-750°C, more preferably 400-700°C, and more preferably 500-600°C; the gas flow rate is preferably 25-26Kg / Hr, more preferably 25.2-25.8Kg / Hr, and more preferably 25.4-25.6Kg / Hr.

[0050] In the present invention, the catalyst used in the scramble recombination is alumina. 12 C 16 O molecules open, 13 C and 18 O is separated and then 16 O combines into molecules, producing more 13 C 16 O components; and operating at high temperatures, exhausting isotopic compounds in the gas.

[0051] In the present invention, the pressure of the low-temperature impurity removal in step (2) is preferably 250-260 psia, more preferably 252-258 psia, more preferably 254-256 psia; the temperature is preferably 200-210K, more preferably 202-208K, more preferably 204-206K; the gas flow rate is preferably 6-6.1Kg / Hr, more preferably 6.02-6.08Kg / Hr, more preferably 6.04-6.06Kg / Hr.

[0052] In the present invention, carbon dioxide and water vapor generated in the frequency scrambling process can be removed by low-temperature impurity removal.

[0053] In the present invention, after scrambling recombination and low-temperature impurity removal, the gas is transported to a three-stage distillation tower.

[0054] In the present invention, the top temperature of the tertiary distillation in step (2) is preferably 90-100K, more preferably 92-98K, more preferably 94-96K; the top pressure is preferably 35-36psia, more preferably 35.2-35.8psia, more preferably 35.4-35.6psia; the temperature in the tower is preferably 165-170K, more preferably 166-169K, more preferably 167-168K; the pressure in the tower is preferably 50-55psia , further preferably 51-54 psia, more preferably 52-53 psia; the bottom temperature is preferably 145-155K, further preferably 146-154K, more preferably 148-152K; the bottom pressure is preferably 62-63psia, further preferably 62.2-62.8psia, more preferably 62.4-62.6psia; the gas flow rate is preferably 35-40g / h, further preferably 36-39g / h, more preferably 37-38g / h.

[0055] In the present invention, the number of cascade reaction columns of the three-stage distillation tower is preferably 2 to 6, more preferably 3 to 5, and even more preferably 4.

[0056] In the present invention, after three-stage distillation, the heavy component gas is greater than or equal to 99% 13 C product, the gas can now be passed into the product tank for storage, or for the next step of distillation.

[0057] In the present invention, the tower top temperature of the quaternary distillation in step (2) is preferably 100-105K, more preferably 101-104K, more preferably 102-103K; the tower top pressure is preferably 23.5-24.5psia, more preferably 23.6-24.4psia, more preferably 23.8-24.2psia; the tower temperature is preferably 135-140K, more preferably 136-139K, more preferably 137-138K; the tower pressure is preferably 24.5-25psia , further preferably 24.6-24.9 psia, more preferably 24.7-24.8 psia; the bottom temperature is preferably 190-195K, further preferably 191-194K, more preferably 192-193K; the bottom pressure is preferably 31.5-32 psia, further preferably 31.6-31.9 psia, more preferably 31.7-31.8 psia; the gas flow rate is preferably 20-30 g / h, further preferably 22-28 g / h, more preferably 24-26 g / h.

[0058] In the present invention, the four-stage distillation is carried out in a four-stage distillation tower, and the number of cascade reaction columns of the four-stage distillation tower is preferably 1 to 2.

[0059] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0060] Example 1

[0061] The raw gas is subjected to low-temperature impurity removal at 300psia and 185K, and then introduced into a normal temperature adsorber for adsorption at 210psia and 275K; then introduced into a de-weighting tower, the pressure is controlled to be 210psia, the temperature is 115K, and the gas flow rate is 4.5kg / h to carry out heavy impurity removal in the de-weighting tower to remove nitrogen, methane and other components in the raw gas, and then the gas is subjected to light impurity removal in a light-weighting tower at 115psia, 110K, and 3.5kg / h to remove oxygen; the gas after light impurity removal is compressed and stored by a compressor, and then subjected to secondary low-temperature impurity removal in a low-temperature cold trap at 300psia and 185K. The gas after the secondary low-temperature impurity removal preliminarily meets industrial requirements and is subjected to subsequent step-by-step distillation.

[0062] The diameter of the distillation tower is 114 cm. The gas after the secondary low-temperature impurity removal is introduced into the primary distillation tower (the cascade reaction columns are 20). The top temperature of the tower is controlled to be 92K, the top pressure of the tower is 19.5psia, the temperature in the tower is 180K, the pressure in the tower is 36.5psia, the bottom temperature of the tower is 296K, the bottom pressure of the tower is 41.5psia, and the gas flow rate is 295g / h for distillation. After the distillation is completed, the isotopic gas of the light component is enriched at the top of the tower, discharged and collected, and the gas of the heavy component is enriched at the bottom of the distillation tower and transported to the cryogenic pump through the gas phase pipeline. Impurities are removed under the conditions of 300psia and 180K, and then the impurity-removed gas is transported to the secondary distillation. In the tower (there are 6 cascade reaction columns), the top temperature is controlled to be 91K, the top pressure is 20.8psia, the temperature in the tower is 152K, the pressure in the tower is 32.8psia, the bottom temperature is 148K, the bottom pressure is 41.2psia, and the gas flow rate is 72g / h for distillation. After the distillation is completed, the isotopic gas of the light component is enriched to the top of the tower and discharged and collected, and the gas of the heavy component is enriched at the bottom of the distillation tower and transported to the cryogenic pump through the gas phase pipeline. Impurities are removed under the conditions of 300psia and 180K, and then the temperature in the scrambler is set to 500℃ and the gas flow rate is 25.5Kg / Hr. More isotopes are produced through the action of high temperature and alumina. 13 C component, and then low-temperature impurity removal is carried out under the conditions of 255psia, 205K, and 6.05Kg / Hr to remove carbon dioxide and water produced in the scrambling process; then the gas is transported into a three-stage distillation tower (three cascade reaction columns), and the top temperature of the tower is controlled to be 98K, the top pressure of the tower is 35.2psia, the temperature in the tower is 166K, the pressure in the tower is 51psia, the bottom temperature of the tower is 148K, the bottom pressure of the tower is 62.6psia, and the gas flow rate is 38g / h for distillation. After the distillation is completed, the isotope gas of the light component is enriched to The gas is discharged from the top of the tower and collected, and the heavy component gas is enriched at the bottom of the distillation tower and transported into the cryogenic pump through the gas phase pipeline. Impurities are removed under the conditions of 300psia and 180K, and then the impurity-free gas is transported into a four-stage distillation tower (one cascade reaction column). The top temperature of the tower is controlled to be 103K, the top pressure of the tower is 23.6psia, the temperature in the tower is 139K, the pressure in the tower is 24.6psia, the bottom temperature of the tower is 194K, the bottom pressure of the tower is 31.9psia, and the gas flow rate is 22g / h for distillation to complete the distillation and collect the gas.

[0063] In this embodiment, after three-stage distillation, 13 The abundance of C product is 99.89% after four-stage distillation. 13 The abundance of C product is 99.999%.

[0064] Example 2

[0065] The raw gas is subjected to low-temperature impurity removal at 285psia and 190K, and then passed into a normal temperature adsorber for adsorption at 205psia and 270K; then it is passed into a de-weighting tower, and the pressure is controlled to be 205psia, the temperature to be 113K, and the gas flow rate to be 4.3kg / h to carry out heavy impurity removal in the de-weighting tower to remove nitrogen, methane and other components in the raw gas; then the gas is subjected to light impurity removal in a light-weighting tower at 118psia, 108K, and 3.6kg / h to remove oxygen; the gas after light impurity removal is compressed and stored by a compressor, and then subjected to secondary low-temperature impurity removal in a low-temperature cold trap at 295psia and 190K. The gas after the secondary low-temperature impurity removal preliminarily meets industrial requirements and is subjected to subsequent step-by-step distillation.

[0066] The diameter of the distillation tower is 112 cm. The gas after the secondary low-temperature impurity removal is introduced into the primary distillation tower (the cascade reaction columns are 25). The top temperature of the tower is controlled to be 94K, the top pressure of the tower is 19.8psia, the temperature in the tower is 175K, the pressure in the tower is 36.4psia, the bottom temperature of the tower is 299K, the bottom pressure of the tower is 41.4psia, and the gas flow rate is 298g / h for distillation. After the distillation is completed, the isotopic gas of the light component is enriched at the top of the tower and discharged and collected. The gas of the heavy component is enriched at the bottom of the distillation tower and transported to the cryogenic pump through the gas phase pipeline. Impurities are removed under the conditions of 310psia and 190K, and then the impurity-removed gas is transported to the secondary distillation. In the tower (5 cascade reaction columns), the top temperature is controlled to be 93K, the top pressure is 20.4psia, the temperature in the tower is 151K, the pressure in the tower is 33.5psia, the bottom temperature is 155K, the bottom pressure is 41.8psia, and the gas flow rate is 71g / h for distillation. After the distillation is completed, the isotopic gas of the light component is enriched to the top of the tower and discharged and collected, and the gas of the heavy component is enriched at the bottom of the distillation tower and transported to the cryogenic pump through the gas phase pipeline. Impurities are removed under the conditions of 310psia and 190K, and then the temperature in the scrambler is set to 410℃ and the gas flow rate is 25.2Kg / Hr. More isotopes are produced through the action of high temperature and alumina. 13C component, and then under the conditions of 260psia, 201K, 6.02Kg / Hr, low-temperature impurity removal is carried out to remove carbon dioxide and water produced in the scrambling process; then the gas is transported into a three-stage distillation tower (4 cascade reaction columns), the tower top temperature is controlled to be 94K, the tower top pressure is 35.2psia, the tower temperature is 169K, the tower pressure is 51psia, the tower bottom temperature is 148K, the tower bottom pressure is 62psia, and the gas flow rate is 36g / h for distillation. After the distillation is completed, the isotope gas of the light component is enriched to the tower The gas is discharged from the top and collected, and the heavy component gas is enriched at the bottom of the distillation tower and transported into the cryogenic pump through the gas phase pipeline. Impurities are removed under the conditions of 310psia and 190K. The impurity-free gas is then transported into a four-stage distillation tower (two cascade reaction columns). The top temperature of the tower is controlled to be 101K, the top pressure of the tower is 23.6psia, the temperature in the tower is 136K, the pressure in the tower is 24.5psia, the bottom temperature of the tower is 193K, the bottom pressure of the tower is 31.7psia, and the gas flow rate is 23g / h for distillation to complete the distillation and collect the gas.

[0067] In this embodiment, after three-stage distillation, 13 The abundance of C product is 99.99%. 13 The abundance of C product is 99.999%.

[0068] Example 3

[0069] The raw gas is subjected to low-temperature impurity removal at 307psia and 182K, and then passed into a normal temperature adsorber for adsorption at 218psia and 274K; then it is passed into a de-weighting tower, and the pressure is controlled to be 219psia, the temperature to be 114K, and the gas flow rate to be 4.7kg / h to carry out heavy impurity removal in the de-weighting tower to remove nitrogen, methane and other components in the raw gas; then the gas is subjected to light impurity removal in a light-weighting tower at 114psia, 116K, and 3.3kg / h to remove oxygen; the gas after light impurity removal is compressed and stored by a compressor, and then subjected to secondary low-temperature impurity removal in a low-temperature cold trap at 301psia and 182K. The gas after the secondary low-temperature impurity removal preliminarily meets industrial requirements and is subjected to subsequent step-by-step distillation.

[0070] The diameter of the distillation tower is 118 cm. The gas after the secondary low-temperature impurity removal is introduced into the primary distillation tower (the cascade reaction columns are 30). The top temperature of the tower is controlled to be 93.5K, the top pressure of the tower is 19.8psia, the temperature in the tower is 178K, the pressure in the tower is 36.3psia, the bottom temperature of the tower is 302K, the bottom pressure of the tower is 41.4psia, and the gas flow rate is 293g / h for distillation. After the distillation is completed, the isotopic gas of the light component is enriched at the top of the tower and discharged and collected, and the gas of the heavy component is enriched at the bottom of the distillation tower and transported to the cryogenic pump through the gas phase pipeline. Impurities are removed under the conditions of 295psia and 188K, and then the impurity-removed gas is transported to the secondary distillation tower. In the distillation tower (8 cascade reaction columns), the top temperature is controlled to be 94K, the top pressure is 20.8psia, the temperature in the tower is 148K, the pressure in the tower is 33.4psia, the bottom temperature is 141K, the bottom pressure is 41.9psia, and the gas flow rate is 71g / h for distillation. After the distillation is completed, the isotopic gas of the light component is enriched to the top of the tower and discharged and collected, and the gas of the heavy component is enriched at the bottom of the distillation tower and transported to the cryogenic pump through the gas phase pipeline. Impurities are removed under the conditions of 295psia and 188K, and then the temperature in the scrambler is set to 740℃ and the gas flow rate is 25.8Kg / Hr. More isotopes are produced through the action of high temperature and alumina. 13 C component, and then low-temperature impurity removal is carried out under the conditions of 252psia, 207K, and 6.04Kg / Hr to remove carbon dioxide and water produced in the scrambling process; the gas is then transported into a three-stage distillation tower (6 cascade reaction columns), and the tower top temperature is controlled to be 98.4K, the tower top pressure is 35.3psia, the tower temperature is 166K, the tower pressure is 53psia, the tower bottom temperature is 152K, the tower bottom pressure is 62.8psia, and the gas flow rate is 39g / h for distillation. After the distillation is completed, the isotope gas of the light component is enriched to The gas from the top of the tower is discharged and collected, and the heavy component gas is enriched at the bottom of the distillation tower and transported into the cryogenic pump through the gas phase pipeline for impurity removal under the conditions of 295psia and 188K. The impurity-free gas is then transported into a four-stage distillation tower (two cascade reaction columns). The top temperature and pressure of the tower are controlled to be 103K and 23.8psia, the temperature in the tower is 137.5K and the pressure in the tower is 24.9psia, the bottom temperature is 191K and the pressure at the bottom is 31.9psia. The gas flow rate is 23g / h for distillation to complete the distillation and gas collection.

[0071] In this embodiment, after three-stage distillation, 13 The abundance of C product is 99.995%, after four-stage distillation 13 The abundance of C product is 99.999%.

[0072] Example 4

[0073] The raw gas is subjected to low-temperature impurity removal at 314psia and 186K, and then passed into a normal temperature adsorber for adsorption at 214psia and 276K; then it is passed into a de-weighting tower, and the pressure is controlled to be 218psia, the temperature to be 115K, and the gas flow rate to be 4.1kg / h to carry out heavy impurity removal in the de-weighting tower to remove components such as nitrogen and methane in the raw gas; then the gas is subjected to light impurity removal in a light-weighting tower at 116psia, 105K, and 3.6kg / h to remove oxygen; the gas after light impurity removal is compressed and stored by a compressor, and then subjected to secondary low-temperature impurity removal in a low-temperature cold trap at 314psia and 190K. The gas after the secondary low-temperature impurity removal preliminarily meets industrial requirements and is subjected to subsequent step-by-step distillation.

[0074] The diameter of the distillation tower is 114 cm. The gas after the secondary low-temperature impurity removal is introduced into the primary distillation tower (the cascade reaction columns are 14). The top temperature of the tower is controlled to be 94K, the top pressure of the tower is 19.1psia, the temperature in the tower is 172K, the pressure in the tower is 36.7psia, the bottom temperature of the tower is 301K, the bottom pressure of the tower is 41.7psia, and the gas flow rate is 295g / h for distillation. After the distillation is completed, the isotopic gas of the light component is enriched at the top of the tower and discharged and collected. The gas of the heavy component is enriched at the bottom of the distillation tower and transported to the cryogenic pump through the gas phase pipeline. Impurities are removed under the conditions of 304psia and 186K, and then the impurity-removed gas is transported to the secondary distillation. In the tower (there are 6 cascade reaction columns), the top temperature is controlled to be 95K, the top pressure is 20.8psia, the temperature in the tower is 158K, the pressure in the tower is 33.2psia, the bottom temperature is 152K, the bottom pressure is 41.6psia, and the gas flow rate is 75g / h for distillation. After the distillation is completed, the isotopic gas of the light component is enriched to the top of the tower and discharged and collected, and the gas of the heavy component is enriched at the bottom of the distillation tower and transported to the cryogenic pump through the gas phase pipeline. Impurities are removed under the conditions of 304psia and 186K, and then the temperature in the scrambler is set to 515℃ and the gas flow rate is 25.6Kg / Hr. More isotopes are produced through the action of high temperature and alumina. 13 C component, and then low-temperature impurity removal is carried out under the conditions of 258psia, 200K, and 6.1Kg / Hr to remove carbon dioxide and water produced in the scrambling process; then the gas is transported into a three-stage distillation tower (4 cascade reaction columns), and the top temperature is controlled to be 98K, the top pressure is 35.4psia, the temperature in the tower is 166K, the pressure in the tower is 54psia, the bottom temperature is 149K, the bottom pressure is 62.4psia, and the gas flow rate is 40g / h for distillation to complete the distillation and collect the gas.

[0075] In this embodiment, after three-stage distillation, 13 The abundance of C product is 99.86%.

[0076] It can be seen from the above embodiments that the present invention provides a step-by-step distillation method to improve 13 The method for determining the isotope abundance of C, wherein the raw material CO is subjected to impurity removal treatment to obtain an intermediate gas; the intermediate gas is subjected to primary distillation, secondary distillation, scrambling recombination, low-temperature impurity removal, tertiary distillation and quaternary distillation in sequence to complete the treatment. The method removes most of the impurities in the raw material gas by removing impurities from the raw material CO, and can meet industrial requirements. It can be seen from the examples that the step-by-step distillation method provided by the present invention finally obtains 13 The abundance of C product can reach 99.999%, which is suitable for various high-demand, high-precision and advanced operations.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A step-by-step distillation method 13 C isotope abundance method, characterized in that It includes the following steps: (1) The raw material CO is treated to remove impurities to obtain intermediate gas; (2) The intermediate gas is sequentially subjected to primary distillation, secondary distillation, scrambling recombination, low-temperature impurity removal, tertiary distillation and quaternary distillation to complete the treatment; The impurity removal treatment in step (1) is low-temperature impurity removal, room-temperature adsorption, heavy impurity removal, light impurity removal and secondary low-temperature impurity removal performed in sequence; The pressure of the low-temperature impurity removal in step (1) is 280-320 psia and the temperature is 180-190K; The pressure of the room temperature adsorption is 200-220psia and the temperature is 270-280K; The pressure of the heavy impurity removal is 200-220psia, the temperature is 110-120K, and the gas flow rate is 4-5kg / h; The light impurity removal process has a pressure of 110-120 psia, a temperature of 100-120 K, and a gas flow rate of 3-4 kg / h; The pressure of the secondary low-temperature impurity removal is 280-320 psia and the temperature is 180-190K; The tower top temperature of the primary distillation in step (2) is 90-95K, the tower top pressure is 19-20psia, the tower temperature is 170-190K, the tower pressure is 36-37psia, the tower bottom temperature is 295-305K, the tower bottom pressure is 41-42psia, and the gas flow rate is 290-300g / h; The tower top temperature of the secondary distillation in step (2) is 90-95K, the tower top pressure is 20-21psia, the tower temperature is 140-160K, the tower pressure is 32.5-33.5psia, the tower bottom temperature is 140-160K, the tower bottom pressure is 41-42psia, and the gas flow rate is 70-75g / h; The scrambling recombination temperature in step (2) is 350-750°C, and the gas flow rate is 25-26 Kg / Hr; The pressure of the low-temperature impurity removal in step (2) is 250-260 psia, the temperature is 200-210K, and the gas flow rate is 6-6.1 Kg / Hr; The top temperature of the tertiary distillation in step (2) is 90-100K, the top pressure is 35-36psia, the temperature in the tower is 165-170K, the pressure in the tower is 50-55psia, the bottom temperature is 145-155K, the bottom pressure is 62-63psia, and the gas flow rate is 35-40g / h; The top temperature of the quaternary distillation in step (2) is 100-105K, the top pressure is 23.5-24.5psia, the temperature in the tower is 135-140K, the pressure in the tower is 24.5-25psia, the bottom temperature is 190-195K, the bottom pressure is 31.5-32psia, and the gas flow rate is 20-30g / h.