Process and apparatus for purifying a medicinal perfluoroalkane

Abstract

The application discloses a purification method and device of medicinal perfluoroalkane, which comprises the following steps: increasing the pressure of raw material gas to more than 0.3 MPa; through an absorption process, the raw material gas is contacted with an absorption liquid in countercurrent, and the content of hydrogen fluoride in the raw material gas is controlled to be less than 0.5 ppm; the raw material gas is introduced into a feed condenser, the gas phase at the outlet of the feed condenser is tail gas, and the liquid phase material at the outlet of the feed condenser is introduced into a pre-separation tower through a feed pressurizing pump; the gas phase material at the top of the pre-separation tower is tail gas, and the liquid phase material at the bottom of the pre-separation tower is sewage; the material from the side line of the pre-separation tower is introduced into a light-removing tower, the material at the top of the light-removing tower is impurity gas, the liquid phase material at the bottom of the light-removing tower is introduced into a heavy-removing tower for further rectification, the bottom of the heavy-removing tower is impurity liquid, and the liquid phase at the top of the heavy-removing tower is obtained to be medicinal perfluoroalkane; the absorption process is a three-stage countercurrent absorption process, which comprises alkali washing, first-stage water washing and second-stage water washing. The purification method and device are simple in process, do not introduce other impurities and low in energy consumption.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of medicinal gas preparation, and particularly relates to a purification method and equipment of medicinal perfluoroalkane. BACKGROUND

[0002] Perfluoroalkane is a colorless gas with good stability, and has very small solubility in water and organic matter. Perfluoroalkane is mainly used for acoustic ultrasonic contrast in the medical field. Perfluoroalkane micro-bubbles can effectively reflect sound waves and be used for enhancing ultrasonic signal backscattering. It has sufficient residence time in blood vessels, can be used as a blood cell tracer, and can reflect the blood perfusion of organs without interfering with hemodynamics.

[0003] In the preparation of perfluoroalkane, fluorination or high-temperature reaction is often involved, so the crude product perfluoroalkane contains many impurities, mainly hydrogen-containing fluorocarbons, olefin fluorocarbons, etc. There are often impurities with boiling points close to that of perfluoroalkane. When the difference between the boiling points of the impurities and perfluoroalkane is less than 15℃, it is difficult to purify them by distillation. For example, the boiling point difference between perfluoropropane (boiling point -36.7℃) and hexafluoropropylene (boiling point -29.4℃) is only 7.3℃, and the energy consumption of conventional distillation separation is high. At the same time, perfluoropropane and hexafluoropropylene have similar structures, and there is almost no difference in molecular size, resulting in high difficulty in adsorption separation, and the pulverization of the adsorbent may lead to excessive heavy metals and particulate matter in perfluoroalkane.

[0004] Patent document CN104529691B discloses a catalytic conversion method for impurities in perfluoroalkane. A heavy metal catalyst such as cobalt or manganese is used to convert impurities with boiling points close to that of perfluoroalkane into impurities with large differences in boiling points from perfluoroalkane, so as to facilitate subsequent distillation and purification treatment. However, heavy metal impurities are introduced, which does not meet the requirements of medicinal perfluoroalkane without introducing other toxic and harmful impurities.

[0005] None of the current perfluoroalkane purification methods considers the preparation conditions of medicinal products, and it is difficult to meet the production requirements of medicinal gas. SUMMARY

[0006] The purpose of the present application is to provide a purification method and equipment of medicinal perfluoroalkane, which is simple in process, does not introduce other impurities, low in energy consumption, effectively removes hydrogen fluoride, near-boiling point impurities and other impurities in perfluoroalkane, and finally realizes the preparation of medicinal perfluoroalkane.

[0007] The purpose of the present application is achieved by the following technical solutions:

[0008] A purification method of medicinal perfluoroalkane, comprising the following steps:

[0009] (1) Increase the pressure of perfluoroalkane raw gas to more than 0.3MPa by a compressor.

[0010] (2) The raw material gas is contacted with the absorption liquid in countercurrent through an absorption process, so that the content of hydrogen fluoride in the raw material gas is controlled to be less than 0.5 ppm.

[0011] (3) The raw material gas after step (2) is introduced into a feed condenser, and the gas phase at the outlet of the feed condenser is tail gas, and the liquid phase material at the outlet of the feed condenser is introduced into a pre-separation column through a feed pressurizing pump. The tail gas contains nitrogen, nitrogen trifluoride and other gases.

[0012] (4) The gas phase material at the top of the pre-separation column is discharged into a tail gas treatment section, and the liquid phase material at the bottom of the pre-separation column is discharged into a waste water treatment section. The gas phase material at the top of the pre-separation column is an easily separable light component tail gas, containing carbon tetrafluoride, hexafluoroethane and the like; and the liquid phase material at the bottom of the pre-separation column is hydrogen fluoride, water and the like.

[0013] (5) The side line material from the pre-separation column is introduced into a light component removal column, the material at the top of the light component removal column is discharged into a waste liquid treatment section, and the liquid phase material at the bottom of the light component removal column is introduced into a heavy component removal column. The material at the top of the light component removal column is a difficult-to-separate light component such as pentafluoroethane.

[0014] (6) The liquid phase material from the bottom of the light component removal column is introduced into the heavy component removal column for further rectification, and the material at the bottom of the heavy component removal column is a liquid impurity, and the liquid phase material at the top of the heavy component removal column is obtained as a medicinal perfluoroalkane. The liquid impurity is mainly a difficult-to-separate impurity such as a near-boiling heavy component.

[0015] The perfluoroalkane refers to perfluoropropane, perfluorobutane and the like.

[0016] The outlet pressure of the compressor is preferably 0.3-1.0 MPa.

[0017] The absorption process is a three-stage countercurrent absorption, including alkali washing, first-stage water washing and second-stage water washing. The alkali washing and the first-stage water washing are used for removing hydrogen fluoride, and the second-stage water washing is used for removing the salt entrained in the alkali washing section. The absorption equipment is respectively an alkali washing column, a first-stage water washing column and a second-stage water washing column.

[0018] The liquid at the outlet of the second-stage water washing column is used as the absorption liquid of the first-stage water washing column, and the absorption liquid at the outlet of the first-stage water washing column is used as the absorption liquid of the alkali washing column after being added with alkali.

[0019] Further, the operating pressure and the operating temperature of the pre-separation column, the light component removal column and the heavy component removal column are respectively:

[0020] The pre-separation column: the operating pressure is 1.5-2.2 MPa, the temperature at the top is 35-65℃, and the temperature at the bottom is 50-100℃;

[0021] The light component removal column: the operating pressure is 1.4-2.0 MPa, the temperature at the top is 40-75℃, and the temperature at the bottom is 60-95℃;

[0022] The operating pressure of the heavy component removal column is 1.2-1.8 MPa, the column top temperature is 38-80 DEG C, and the column bottom temperature is 55-100 DEG C.

[0023] The mass ratio of the flow rate of the side-draw material of the pre-separation column to the content of the perfluoroalkane in the feed is (1-1.5):1.

[0024] A device used in a method for purifying a medicinal perfluoroalkane, comprising an acid removal system, a pre-separation column, a light component removal column, and a heavy component removal column, wherein a compressor is connected to the front end of the acid removal system, the acid removal system is connected to the middle part of the pre-separation column through a feed condenser and a feed pressurizing pump, a light component venting pipeline is connected to the top of the pre-separation column, a heavy component waste pipeline is connected to the bottom of the pre-separation column, a side-draw pipeline in the middle part of the pre-separation column is connected to the middle part of the light component removal column, a difficult-to-separate light component pipeline is connected to the top of the light component removal column, a pipeline in the bottom of the light component removal column is connected to the middle part of the heavy component removal column, a perfluoroalkane outlet pipeline is connected to the top of the heavy component removal column, and a near-boiling-point heavy component impurity pipeline is connected to the bottom of the heavy component removal column.

[0025] The pre-separation column is a side-draw column, and the side-draw position is in the middle or lower part of the column.

[0026] Further, the pre-separation column, the light component removal column, and the heavy component removal column are all pressurized rectification columns.

[0027] Compared with the prior art, the present application has the following advantages due to the use of the above technical solutions:

[0028] (1) The absorption process adopts the mode of alkali washing + water washing + water washing, which can reduce the amount of absorption liquid, and the secondary water washing avoids the salt produced by alkali washing from entering the subsequent separation section, thereby meeting the requirements for medicinal use;

[0029] (2) The side-draw of the pre-separation column in the rectification process can achieve the removal of a large amount of light impurities and heavy impurities, thereby reducing the separation difficulty, and the subsequent light component removal column and heavy component removal column can easily prepare medicinal perfluoroalkane meeting the purity requirements;

[0030] (3) The rectification process adopts high-pressure separation, and the column top can be cooled by circulating water, thereby avoiding the introduction of high-value refrigerated water;

[0031] (4) Compared with the prior art method, the present application has low energy consumption and produces less waste liquid, which is conducive to engineering amplification and environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic diagram of the process flow of the present application.

[0033] In the figure, 1, raw material gas feed line; 2, compressor; 3, caustic washing tower; 4, first-stage water washing tower; 5, second-stage water washing tower; 6, caustic solution separator; 7, caustic solution delivery pump; 8, first-stage water washing tower clean water pump; 9, second-stage water washing tower clean water pump; 10, water separator; 11, feed condenser; 12, feed pressurizing pump; 13, pre-separation tower; 14, light component removal tower; 15, heavy component removal tower; 16, caustic addition line; 17, clean water line; 18, waste water blowdown line; 19, non-condensable gas vent line; 20, easily separable light component vent line; 21, side line production line; 22, heavy component blowdown line; 23, difficult-to-separate light component line; 24, light component removal tower bottom product line; 25, perfluoroalkane product line; 26, near-boiling point heavy component impurity line; 27, caustic solution separator blowdown line; 28, caustic solution blowdown line. DETAILED DESCRIPTION

[0034] The technical solutions of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0035] As Figure 1As shown, a purification method of a pharmaceutical perfluoroalkane uses equipment including a deacidification system, a pre-separation tower 13, a light component removal tower 14, and a heavy component removal tower 15. The raw material gas inlet pipeline 1 is connected to the inlet of the compressor 2, and the deacidification system is connected to the outlet of the compressor 2. The feed condenser 11 is connected to the deacidification system, and the non-condensable gas vent pipeline 19 is connected to the feed condenser 11. The feed pressurizing pump 12 is connected to the middle of the pre-separation tower 13. The easily separated light component vent pipeline 20 is connected to the top of the pre-separation tower 13. The heavy component discharge pipeline 22 is connected to the bottom of the pre-separation tower 13. The difficultly separated light component pipeline 23 is connected to the top of the light component removal tower 14. The light component removal tower 14 is connected to the middle of the heavy component removal tower 15 through the light component removal tower outlet pipeline 24. The perfluoroalkane outlet pipeline 25 is connected to the top of the heavy component removal tower 15. The near-boiling-point heavy component impurity pipeline 26 is connected to the bottom of the heavy component removal tower 15. The deacidification system includes the alkali washing tower 3, the first-stage water washing tower 4, and the second-stage water washing tower 5 connected in series. The alkali liquid separator 6 is arranged on the pipeline connecting the top of the alkali washing tower 3 and the lower part of the first-stage water washing tower 4. The alkali liquid separator discharge pipeline 27 is connected to the alkali liquid separator 6. The alkali liquid discharge pipeline 28 is connected to the bottom of the alkali washing tower 3. The alkali liquid delivery pump 7 is arranged on the pipeline connecting the upper part of the alkali washing tower 3 and the bottom of the first-stage water washing tower 4. The alkali liquid delivery pump 7 is connected to the inlet of the alkali adding pipeline 16 and the bottom of the first-stage water washing tower 4. The first-stage water washing tower clean water pump 8 is arranged on the pipeline connecting the upper part of the first-stage water washing tower 4 and the bottom of the second-stage water washing tower 5. The second-stage water washing tower clean water pump 9 is arranged on the upper part of the second-stage water washing tower 5. The second-stage water washing tower clean water pump 9 is connected to the front end of the clean water pipeline 17. The feed condenser 11 is connected to the water separator 10 on the top of the second-stage water washing tower 5. The waste water discharge pipeline 18 is connected to the bottom of the water separator.

[0036] In a preferred embodiment, the pre-separation tower 13 is a side-draw tower.

[0037] In a preferred embodiment, the pre-separation tower 13 is a side-draw tower.

[0038] In a preferred embodiment, the pre-separation tower 13, the light component removal tower 14, and the heavy component removal tower 15 are all pressurized rectifying towers.

[0039] A purification method of a pharmaceutical perfluoroalkane includes the following steps:

[0040] (1) The perfluoroalkane raw material gas is pressurized to 0.3 MPa or above by a compressor.

[0041] (2) The hydrogen fluoride content in the raw material gas is controlled to be less than 0.5 ppm by countercurrent contact between the raw material gas and the absorption liquid through an absorption process.

[0042] (3) The raw material gas from step (2) is passed into a feed condenser, and the gas phase at the outlet of the feed condenser is tail gas, and the liquid phase material at the outlet of the feed condenser is passed into a pre-separation column through a feed pressurizing pump. The tail gas contains nitrogen, nitrogen trifluoride and other gases.

[0043] (4) The gas phase material at the top of the pre-separation column is discharged into a tail gas treatment section, and the liquid phase material at the bottom of the pre-separation column is discharged into a waste liquid treatment section. The gas phase material at the top of the pre-separation column is an easily separable light component tail gas containing carbon tetrafluoride, hexafluoroethane and the like; and the liquid phase material at the bottom of the pre-separation column is hydrogen fluoride, water and the like.

[0044] (5) The side line material from the pre-separation column is passed into a light component removal column, the material at the top of the light component removal column is discharged into a waste liquid treatment section, and the liquid phase material at the bottom of the light component removal column is passed into a heavy component removal column. The material at the top of the light component removal column is a difficult-to-separate light component containing pentafluoroethane.

[0045] (6) The liquid phase material from the bottom of the light component removal column is passed into the heavy component removal column for further rectification, and the material at the bottom of the heavy component removal column is a liquid impurity, and the liquid phase material at the top of the heavy component removal column is obtained as a medicinal perfluoroalkane. The liquid impurity is mainly a difficult-to-separate impurity such as a near-boiling heavy component.

[0046] In a preferred embodiment, the outlet pressure of the compressor is 0.3-1.0 MPa.

[0047] In a preferred embodiment, the absorption process is a three-stage countercurrent absorption, including an alkali washing column, a first-stage water washing column and a second-stage water washing column. The alkali washing column and the first-stage water washing column are used for removing hydrogen fluoride, and the second-stage water washing column is used for removing salt entrained in the alkali washing section.

[0048] In a preferred embodiment, the outlet liquid of the second-stage water washing column is used as the absorption liquid of the first-stage water washing column, and the outlet absorption liquid of the first-stage water washing column is used as the absorption liquid of the alkali washing column after being added with alkali, and further, the alkali is preferably potassium hydroxide or sodium hydroxide.

[0049] In a preferred embodiment, the operating pressure and the operating temperature of the pre-separation column, the light component removal column and the heavy component removal column are respectively as follows:

[0050] The pre-separation column: the operating pressure is 1.5-2.2 MPa, the temperature at the top is 35-65℃, and the temperature at the bottom is 50-100℃;

[0051] The light component removal column: the operating pressure is 1.4-2.0 MPa, the temperature at the top is 40-75℃, and the temperature at the bottom is 60-95℃;

[0052] The heavy component removal column: the operating pressure is 1.2-1.8 MPa, the temperature at the top is 38-80℃, and the temperature at the bottom is 55-100℃.

[0053] In a preferred embodiment, the mass ratio of the flow rate of the side line material from the pre-separation column to the content of the perfluoroalkane in the feed is (1-1.5):1.

[0054] Example 1

[0055] The crude perfluoropropane gas used in the present application is synthesized from perfluoropropene as raw material, and the indexes are shown in Table 1.

[0056] Table 1 Composition of crude perfluoropropane gas in Example 1

[0057]

[0058] The crude perfluoropropane gas in Table 1 is pressurized to 0.8 MPa by means of a compressor at a processing capacity of 300 kg / h, and the operating conditions are shown in Table 2. After being washed by alkali and secondary water according to the present application, the hydrogen fluoride content at the outlet is detected to be 0.3 ppm, which is sent to the rectification section. The medicinal perfluoropropane prepared is shown in Table 3.

[0059] Table 2 Operating conditions of Example 1

[0060]

[0061] Table 3 Product test results of Example 1

[0062]

[0063] Example 2

[0064] The crude perfluorobutane gas used in Example 2 is synthesized from perfluoro-1-butene as raw material, and the indexes are shown in Table 4.

[0065] Table 4 Composition of crude perfluorobutane gas in Example 2

[0066]

[0067] The crude perfluorobutane gas in Table 4 is pressurized to 0.7 MPa by means of a compressor at a processing capacity of 400 kg / h, and the operating conditions are shown in Table 5. After being washed by alkali and secondary water according to the present application, the hydrogen fluoride content at the outlet is detected to be 0.36 ppm, which is sent to the rectification section. The medicinal perfluorobutane prepared is shown in Table 6.

[0068] Table 5 Operating conditions of Example 2

[0069]

[0070] Table 6 Product test results of Example 2

[0071]

[0072] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for purifying a pharmaceutical perfluoroalkane, characterized by, It comprises the following steps: (1) increasing the pressure of the perfluoroalkane raw gas to above 0.3 MPa by a compressor; (2) controlling the hydrogen fluoride content in the raw gas to below 0.5 ppm by countercurrent contact of the raw gas with absorbing liquid through an absorbing process; (3) passing the raw gas after step (2) into a feed condenser, with the gas phase at the outlet of the feed condenser being tail gas, and the liquid phase material at the outlet of the feed condenser being passed into a pre-separation tower through a feed pressurizing pump; (4) discharging the gas phase material at the top of the pre-separation tower into a tail gas treatment section, and discharging the liquid phase material at the bottom of the pre-separation tower into a waste water treatment section; (5) passing the material from the side line of the pre-separation tower into a light component removal tower, discharging the material at the top of the light component removal tower into a waste liquid treatment section, and passing the liquid phase material at the bottom of the light component removal tower into a heavy component removal tower; (6) passing the liquid phase material from the bottom of the light component removal tower into the heavy component removal tower for further rectification, with the material at the bottom being liquid impurities, and the liquid phase material at the top being a medicinal perfluoroalkane; The perfluoroalkane refers to perfluoropropane and perfluorobutane. The absorbing process is a three-stage countercurrent absorption, comprising alkali washing, first-stage water washing and second-stage water washing.

2. The purification method according to claim 1, characterized in that, The absorbing equipment comprises an alkali washing tower, a first-stage water washing tower and a second-stage water washing tower.

3. The purification method of claim 2, wherein, The liquid at the outlet of the second-stage water washing tower is used as the absorbing liquid of the first-stage water washing tower, and the absorbing liquid at the outlet of the first-stage water washing tower is used as the absorbing liquid of the alkali washing tower after being mixed with alkali.

4. The purification method of claim 1, wherein, The operating pressure and temperature of the pre-separation tower, the light component removal tower and the heavy component removal tower are as follows: Pre-separation tower: operating pressure 1.5-2.2 MPa, top temperature 35-65℃, bottom temperature 50-100℃; Light component removal tower: operating pressure 1.4-2.0 MPa, top temperature 40-75℃, bottom temperature 60-95℃; Heavy component removal tower: operating pressure 1.2-1.8 MPa, top temperature 38-80℃, bottom temperature 55-100℃.

5. The purification method of claim 1, wherein, The mass ratio of the flow rate of the material from the side line of the pre-separation tower to the content of the perfluoroalkane in the feed is (1-1.5):

1.

6. The purification method of claim 1, wherein, The outlet pressure of the compressor is 0.3-1.0 MPa.

7. An apparatus for use in a purification process according to any one of claims 1 to 6, characterized in that The system comprises a deacidification system, a pre-separation tower (13), a light component removal tower (14), and a heavy component removal tower (15). The deacidification system is connected to a compressor (2) at the front end, and is connected to the middle part of the pre-separation tower (13) through a feed condenser (11) and a feed pressurizing pump (12) at the rear end. The pre-separation tower (13) is connected to an easily separated light component venting pipeline (20) at the top, and is connected to a heavy component waste pipeline (22) at the bottom. The middle part of the pre-separation tower (13) is connected to a light component removal pipeline (23) at the top of the light component removal tower (14), and is connected to the middle part of the heavy component removal tower (15) through the tower bottom pipeline of the light component removal tower (14). The top of the heavy component removal tower (15) is connected to a perfluoroalkane outlet pipeline (25), and the bottom of the heavy component removal tower (15) is connected to a near-boiling point heavy component impurity pipeline (26). The deacidification system comprises an alkali washing tower (3), a first-stage water washing tower (4), and a second-stage water washing tower (5) connected in series. An alkali liquid separator (6) is arranged on the pipeline connecting the top of the alkali washing tower (3) and the lower part of the first-stage water washing tower (4). An alkali liquid delivery pump (7) is arranged on the pipeline connecting the upper part of the alkali washing tower (3) and the bottom of the first-stage water washing tower (4). A first-stage water washing tower clean water pump (8) is arranged on the pipeline connecting the upper part of the first-stage water washing tower (4) and the bottom of the second-stage water washing tower (5). A second-stage water washing tower clean water pump (9) is arranged at the upper part of the second-stage water washing tower (5), and the top of the second-stage water washing tower (5) is connected to the feed condenser (11) through a water separator (10).

8. The apparatus of claim 7, wherein, The pre-separation tower (13) is a side-draw tower, and the draw position is the middle or lower part of the tower body.

9. The apparatus of claim 7, wherein, The pre-separation tower (13), the light component removal tower (14), and the heavy component removal tower (15) are all pressurized rectifying towers.

10. The apparatus of any one of claims 7-9, wherein, The system further comprises a raw material gas feed pipeline (1), an alkali adding pipeline (16), a clean water pipeline (17), a waste water waste pipeline (18), a non-condensable gas venting pipeline (19), a light component removal tower tower bottom outlet pipeline (24), an alkali liquid separator waste pipeline (27), and an alkali liquid waste pipeline (28).

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