阅读说明：本技术 一种电子级六氟化硫的多级制备方法 (Multistage preparation method of electronic grade sulfur hexafluoride ) 是由 华祥斌 赖金香 张朝春 刘志强 罗浩 邱桂祥 于 2021-02-02 设计创作，主要内容包括：本发明提供了一种电子级六氟化硫的多级制备方法,包括：将氟气通入卧式SF-6反应单元,并与硫磺蒸汽在195～205℃持续反应形成SF-6粗气；将反应单元SF-6粗气除尘后通入热解单元中,将SF-6粗气中的S-2F-(10)气体热解；将步骤S2处理后的混合气体通入水洗单元进行水洗,得到一级纯化气体；将反应单元一级纯化气体通入碱洗单元进行碱洗,得到二级纯化气体；将反应单元二级纯化气体通入水气分离单元以去除水分得到三级纯化气体；将反应单元三级纯化气体通入低压吸附单元中吸附,得到四级纯化气体；将反应单元四级纯化气体通入高压吸附单元中吸附得到五级纯化气体；将反应单元五级纯化气体通入精馏单元进行精馏,得到电子级六氟化硫。(The invention provides a multistage preparation method of electronic grade sulfur hexafluoride, which comprises the following steps: fluorine gas is introduced into horizontal SF 6 A reaction unit, and reacting with sulfur steam at 195-205 deg.C to form SF 6 Coarse gas; reaction unit SF 6 Introducing the crude gas into a pyrolysis unit after dust removal, and introducing SF into the pyrolysis unit 6 S in crude gas 2 F 10 Pyrolyzing the gas; introducing the mixed gas treated in the step S2 into a washing unit for washing to obtain primary purified gas; introducing the primary purified gas of the reaction unit into an alkali washing unit for alkali washing to obtain secondary purified gas; introducing the second-stage purified gas of the reaction unit into a water-gas separation unit to remove water to obtain third-stage purified gas; introducing the three-stage purified gas of the reaction unit into a low-pressure adsorption unit for adsorption to obtain four-stage purified gas; introducing the four-stage purified gas of the reaction unit into a high-pressure adsorption unit for adsorption to obtain five-stage purified gas; and introducing the fifth-grade purified gas of the reaction unit into a rectification unit for rectification to obtain the electronic-grade sulfur hexafluoride.)

1. The multistage preparation method of the electronic grade sulfur hexafluoride is characterized by comprising the following steps:

s1, fluorine gas is led into horizontal SF₆A reaction unit, wherein sulfur continuously enters the reaction chamber and is heated to form sulfur steam which continuously reacts with the fluorine gas at 195-205 ℃ to form SF₆Coarse gas;

s2, mixing the SF₆Introducing the crude gas into a pyrolysis unit after dust removal, and introducing SF into the pyrolysis unit₆S in crude gas₂F₁₀Decomposition of gas to SF₆And SF₄；

S3, introducing the mixed gas treated in the step S2 into a water washing unit for water washing, and removing fluorine gas and low-sulfur fluoride in the mixed gas to obtain primary purified gas;

s4, introducing the primary purified gas into an alkali washing unit for alkali washing to remove HF and CO₂、SO₂Gas to obtain secondary purified gas;

s5, introducing the secondary purified gas into a water-gas separation unit to remove moisture to obtain a tertiary purified gas;

s6, introducing the three-stage purified gas into a low-pressure adsorption unit for adsorption, and removing trace moisture and acidic substances to obtain four-stage purified gas;

s7, introducing the four-stage purified gas into a high-pressure adsorption unit to adsorb low-sulfur oxyfluoride and trace HF and H₂O, obtainingPurifying the gas in five stages;

and S8, introducing the five-stage purified gas into a rectification unit for rectification and impurity removal to obtain the electronic-grade sulfur hexafluoride.

2. The multi-stage process for the preparation of electronic grade sulphur hexafluoride of claim 1, wherein in step S1, said horizontal SF is₆The reaction unit comprises a first horizontal SF connected in series₆Reactor (1) and second horizontal SF₆A reactor (2), and in step S1, the fluorine gas is passed through the horizontal SF₆A reaction unit, wherein sulfur continuously enters the reaction chamber and is heated to form sulfur steam which continuously reacts with the fluorine gas at 195-205 ℃ to form SF₆The crude gas step comprises:

s11, introducing the fluorine gas and the sulfur into the first horizontal SF₆The reactor (1) is controlled to continuously react at the reaction temperature of 200-205 ℃;

s22, mixing the first horizontal SF₆The reaction product of the reactor (1) is introduced into the second horizontal SF₆And the reaction temperature of the reactor (2) is controlled to be 190-200 ℃ for continuous reaction.

3. The multistage preparation method of electronic grade sulphur hexafluoride according to claim 1, wherein in step S2, the pyrolysis unit includes a first pyrolysis tower (4), a second pyrolysis tower (5), and an on-line analyzer (6) arranged in series, and in step S2, the SF is subjected to the on-line analyzer₆The step of introducing the crude gas into the pyrolysis tower after dedusting comprises the following steps:

s21, controlling the temperature of the first pyrolysis tower (4) to be 300-310 ℃ relative to the S₂F₁₀The gas is pyrolyzed and analyzed S by the on-line analyzer (6)₂F₁₀Gas content when said S₂F₁₀When the gas concentration is higher than a first threshold value, the temperature of the second pyrolysis tower (5) is increased, otherwise, the temperature of the second pyrolysis tower (5) is kept the same as the temperature of the first pyrolysis tower (4).

4. The multistage preparation method of electronic grade sulphur hexafluoride according to claim 1, wherein in step S3, the water washing unit includes a first stage water washing tower (7), a second stage water washing tower (8), a third stage water washing tower (9), and a fourth stage water washing tower (10) connected in series.

5. The multistage process for the production of electronic grade sulphur hexafluoride as claimed in claim 1, wherein in step S4, the caustic wash unit includes a first stage caustic wash tower (11), a second stage caustic wash tower (12), a third stage caustic wash tower (13), and a fourth stage caustic wash tower (14) connected in series.

6. The multistage preparation method of electronic grade sulphur hexafluoride according to claim 1, wherein in step S5, the water-gas separation unit includes a gas pump (15), a water-gas separator (16), a cyclone separator (17), and a freeze dryer (18) connected in series; the water discharge pipe of the water-gas separator (16) is arranged higher than the bottom of the water-gas separator (16) to form a water seal; the cyclone separator (17) and the cold dryer (18) are arranged at the top of the water-gas separator (16), and a drain pipe (171) of the cyclone separator (17) and a drain pipe (181) of the cold dryer (18) both extend into the water seal of the water-gas separator (16) so as to realize automatic drainage of the water-gas separator (16), the cyclone separator (17) and the cold dryer (18).

7. The multistage preparation method of electronic grade sulfur hexafluoride according to claim 1, wherein in step S6, the low pressure adsorption unit includes four stages of silica gel adsorption columns (19) connected in series in sequence and four stages of alumina gel adsorption columns (20) connected in series in sequence after the four stages of silica gel adsorption columns (19).

8. The multistage preparation method of electronic grade sulfur hexafluoride as claimed in claim 1, wherein in step S7, the high pressure adsorption unit includes a diaphragm compressor (21), an oil remover (22), a buffer tank (23), a first alumina gel adsorption tower (20), a 5A molecular sieve adsorption tower (24), a 13X molecular sieve adsorption tower (25), a CUCL molecular sieve adsorption tower (26), and an F-03 molecular sieve adsorption tower (27) connected in series in this order.

9. The multistage preparation method of electronic grade sulfur hexafluoride according to claim 1, wherein in step S8, the rectification unit includes a first-stage rectification column (28), a second-stage rectification column (29) and a third-stage rectification column (30), wherein the rectification for removing impurities includes:

the tower top temperature of the first-stage rectifying tower (28), the second-stage rectifying tower (29) and the third-stage rectifying tower (30) is controlled to be-3 ℃ to-5 ℃, and the tower bottom temperature is controlled to be 0 ℃ to 2 ℃.

Technical Field

The invention relates to a multistage preparation method of electronic grade sulfur hexafluoride.

Background

The sulfur hexafluoride is a stable gas which is colorless, odorless, nontoxic and noncombustible, the molecular structure of the sulfur hexafluoride is arranged in an octahedron shape, the bonding distance is small, the bonding energy is high, the stability of the sulfur hexafluoride is very high, and the sulfur hexafluoride is similar to the compatibility of an electrical structure material and nitrogen when the temperature is not more than 180 ℃. Is often used for the new generation of ultra-high voltage insulating dielectric materials and gas insulators for electronic devices and radar waveguides. Electronic grade sulfur hexafluoride (purity over 99.999%) is one of the electronic gases. High-purity SF₆Is an ideal electronic etching agent and is widely applied to the technical field of microelectronics. High-purity SF used in electronic industry of China at present₆It is also mainly an inlet. At present, the purity of industrial sulfur hexafluoride of domestic manufacturers is more than 99.9 percent, and the industrial sulfur hexafluoride sold in the market is taken as the main raw material. In summary, there is a need for a multistage preparation method of electronic grade sulfur hexafluoride in China to solve the existing problems.

Disclosure of Invention

The invention provides a multistage preparation method of electronic grade sulfur hexafluoride, which can effectively solve the problems.

The invention is realized by the following steps:

a multistage preparation method of electronic grade sulfur hexafluoride comprises the following steps:

s1, fluorine gas is led into horizontal SF₆A reaction unit, wherein sulfur continuously enters the reaction chamber and is heated to form sulfur steam which continuously reacts with the fluorine gas at 195-205 ℃ to form SF₆Coarse gas;

s2, mixing the SF₆Introducing the crude gas into a pyrolysis unit after dust removal, and introducing SF into the pyrolysis unit₆S in crude gas₂F₁₀Decomposition of gas to SF₆And SF₄；

S3, introducing the mixed gas treated in the step S2 into a water washing unit for water washing, and removing fluorine gas and low-sulfur fluoride in the mixed gas to obtain primary purified gas;

s4, converting the first stage into a second stageIntroducing the purified gas into an alkali washing unit for alkali washing to remove HF and CO₂、SO₂Gas to obtain secondary purified gas;

s5, introducing the secondary purified gas into a water-gas separation unit to remove moisture to obtain a tertiary purified gas;

s6, introducing the three-stage purified gas into a low-pressure adsorption unit for adsorption, and removing trace moisture and acidic substances to obtain four-stage purified gas;

s7, introducing the four-stage purified gas into a high-pressure adsorption unit to adsorb low-sulfur oxyfluoride and trace HF and H₂O, obtaining five-stage purified gas;

and S8, introducing the five-stage purified gas into a rectification unit for rectification and impurity removal to obtain the electronic-grade sulfur hexafluoride.

The invention has the beneficial effects that: the preparation method provided by the invention is characterized in that fluorine gas prepared by an electrolytic cell enters a reactor through a fluorine gas pipeline and reacts with sulfur steam under certain conditions to generate SF₆And an intermediate fluorine-sulfur compound. SF₆And (3) feeding the crude gas into a water scrubber after passing through a dust remover and a pyrolysis tower, wherein other low fluoride and oxyfluoride in the water scrubber can be hydrolyzed, and feeding the gas after water scrubbing into an alkaline washing tower for leaching by using KOH solution. Firstly, absorbing acid gas HF generated by hydrolysis by water; then KOH solution is used for washing and neutralization, and the removal rate of the hydrogen fluoride reaches more than 99 percent. Washed SF₆After the moisture of the gas is removed, the SF is removed by a multi-stage low-pressure adsorption tower and a multi-stage high-pressure adsorption tower₆The continuous process method can be used for industrially producing electronic grade sulfur hexafluoride so as to solve the bottleneck that the existing domestic electronic grade sulfur hexafluoride cannot be industrially produced depending on import.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a flow chart of a multistage preparation method of electronic grade sulfur hexafluoride according to an embodiment of the present invention.

FIG. 2 shows horizontal SF in the multi-stage preparation method of electronic grade sulfur hexafluoride according to the embodiment of the present invention₆The reaction unit and the pyrolysis unit are schematically shown in the structure.

Fig. 3 is a schematic structural diagram of a water washing unit in the multistage preparation method of electronic grade sulfur hexafluoride provided by the embodiment of the invention.

Fig. 4 is a schematic structural diagram of an alkaline washing unit in the multistage preparation method of electronic grade sulfur hexafluoride provided by the embodiment of the invention.

Fig. 5 is a schematic structural diagram of a water-gas separation unit in the multistage preparation method of electronic grade sulfur hexafluoride provided by the embodiment of the invention.

Fig. 6 is a schematic structural diagram of a low-pressure adsorption unit in the multistage preparation method of electronic-grade sulfur hexafluoride provided in the embodiment of the present invention.

Fig. 7 is a schematic structural diagram of a high-pressure adsorption unit in the multistage preparation method of electronic grade sulfur hexafluoride provided in the embodiment of the present invention.

Fig. 8 is a schematic structural diagram of a rectifying unit in the multistage preparation method of electronic grade sulfur hexafluoride provided by the embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

Referring to fig. 1, an embodiment of the present invention provides a multistage preparation method of electronic grade sulfur hexafluoride, including the following steps:

s1, fluorine gas is led into horizontal SF₆A reaction unit, wherein sulfur continuously enters the reaction chamber and is heated to form sulfur steam which continuously reacts with the fluorine gas at 195-205 ℃ to form SF₆Coarse gas;

s2, mixing the SF₆Introducing the crude gas into a pyrolysis unit after dust removal, and introducing SF into the pyrolysis unit₆S in crude gas₂F₁₀Decomposition of gas to SF₆And SF₄；

S3, introducing the mixed gas treated in the step S2 into a water washing unit for water washing, and removing fluorine gas and low-sulfur fluoride in the mixed gas to obtain primary purified gas;

s4, introducing the primary purified gas into an alkali washing unit for alkali washing to remove HF and CO₂、SO₂Gas to obtain secondary purified gas;

s5, introducing the secondary purified gas into a water-gas separation unit to remove moisture to obtain a tertiary purified gas;

s6, introducing the three-stage purified gas into a low-pressure adsorption unit for adsorption, and removing trace moisture and acidic substances to obtain four-stage purified gas;

s7, introducing the four-stage purified gas into a high-pressure adsorption unit to adsorb low-sulfur fluorineSubstance and trace amounts of HF and H₂O, obtaining five-stage purified gas;

and S8, introducing the five-stage purified gas into a rectification unit for rectification and impurity removal to obtain the electronic-grade sulfur hexafluoride.

Referring to fig. 2, in step S1, the horizontal SF₆The reaction unit comprises a first horizontal SF connected in series₆Reactor 1 and second horizontal SF₆Reactor 2 and in step S1, the fluorine gas is passed through the horizontal SF₆A reaction unit, wherein sulfur continuously enters the reaction chamber and is heated to form sulfur steam which continuously reacts with the fluorine gas at 195-205 ℃ to form SF₆The crude gas step comprises:

s11, introducing the fluorine gas and the sulfur into the first horizontal SF₆The reaction temperature of the reactor 1 is controlled to be 200-205 ℃ for continuous reaction;

s22, mixing the first horizontal SF₆The reaction product of the reactor 1 is introduced into the second horizontal SF₆And 2, controlling the reaction temperature to be 190-200 ℃ for continuous reaction.

It will be appreciated that since sulfur reacts more vigorously with fluorine gas, by dispersing part of the reaction in the second horizontal SF₆In the reactor 2, so that the first horizontal SF can be reduced₆Risk of the reactor 1, in addition, due to the second horizontal SF₆The material concentration of the reactor 2 is reduced, so that the reaction temperature can be properly reduced, and the energy is saved.

Referring to fig. 2, the pyrolysis unit includes a first pyrolysis tower 4, a second pyrolysis tower 5, and an on-line analyzer 6, which are arranged in series, in step S2, and the SF is mixed with the raw material in step S2₆The step of introducing the crude gas into the pyrolysis tower after dedusting comprises the following steps:

s21, controlling the temperature of the first pyrolysis tower 4 to be 300-310 ℃ relative to S₂F₁₀The gas is pyrolyzed and analyzed by the on-line analyzer 6₂F₁₀Gas content when said S₂F₁₀When the gas concentration is higher than the first threshold value, the temperature of the second pyrolysis tower 5 is increased, otherwise, the temperature of the second pyrolysis tower 5 and the first pyrolysis tower 4 are maintainedThe temperature of (2) is the same.

It is understood that when S is said₂F₁₀When the gas concentration is higher than the first threshold value, S can be understood as₂F₁₀The gas decomposition is not complete, and therefore, it is necessary to increase the temperature of the second pyrolysis tower 5. Preferably, the step of increasing the temperature of the second pyrolysis tower 5 is: and increasing the temperature of the second pyrolysis tower 5 to 310-315 ℃.

Referring to fig. 3, in step S3, the water washing unit includes a first-stage water washing tower 7, a second-stage water washing tower 8, a third-stage water washing tower 9, and a fourth-stage water washing tower 10 connected in series. Other subfluorides and oxyfluorides can be hydrolyzed and removed in the water washing tower. The primary water washing tower 7 and the secondary water washing tower 8 mainly perform hydrolysis, and the tertiary water washing tower 9 and the quaternary water washing tower 10 mainly absorb hydrolysate HF.

Referring to fig. 4, in step S4, the caustic washing unit includes a first-stage caustic washing tower 11, a second-stage caustic washing tower 12, a third-stage caustic washing tower 13, and a fourth-stage caustic washing tower 14 connected in series. The residual gas HF generated by hydrolysis is firstly absorbed by water and then is washed and neutralized by KOH solution, and the removal rate of the hydrogen fluoride reaches more than 99 percent.

Referring to fig. 5, in step S5, the water-air separation unit includes an air pump 15, a water-air separator 16, a cyclone separator 17, and a cold dryer 18 connected in sequence; the water discharge pipe of the water-gas separator 16 is arranged higher than the bottom of the water-gas separator 16 to form a water seal; the cyclone separator 17 and the cooling dryer 18 are arranged at the top of the moisture separator 16, and the drain pipe 171 of the cyclone separator 17 and the drain pipe 181 of the cooling dryer 18 both extend into the water seal of the moisture separator 16, so as to realize automatic drainage of the moisture separator 16, the cyclone separator 17 and the cooling dryer 18. It can be understood that the removal rate of the water gas in the gas can reach more than 98% through the three-stage water gas treatment. In addition, the height of the water seal in the water-gas separator 16 is preferably 0.4-0.5 m. Too high water seal height affects the removal rate of water vapor, and too low water seal easily causes the product gas to have too low discharge pressure through the water seal, thus causing pollution and waste.

Referring to fig. 6, in step S6, the low-pressure adsorption unit includes four stages of silica gel adsorption towers 19 connected in series in sequence and four stages of alumina gel adsorption towers 20 connected in series in sequence after the four stages of silica gel adsorption towers 19. Its main function is to remove moisture.

Referring to fig. 7, in step S7, the high-pressure adsorption unit includes a diaphragm compressor 21, an oil remover 22, a buffer tank 23, a first alumina gel adsorption tower 20, a 5A molecular sieve adsorption tower 24, a 13X molecular sieve adsorption tower 25, a CUCL molecular sieve adsorption tower 26, and a F-03 molecular sieve adsorption tower 27, which are connected in series in sequence. When the relative humidity of the sulfur hexafluoride is high, the moisture adsorption capacity of molecular sieve adsorbents such as 5A, 13X, CUCL and F-03 is not different from that of silica gel adsorbents and aluminum gel adsorbents, and when the relative humidity of the sulfur hexafluoride is low, the moisture adsorption capacity of the molecular sieve adsorbents such as 5A, 13X, CUCL and F-03 is much higher than that of the silica gel adsorbents and the aluminum gel adsorbents; the adsorption capacity of the molecular sieve adsorbent is far greater than that of the silica gel alumina adsorbent in the aspect of low fluoride adsorption capacity, but after a large amount of moisture is adsorbed by one molecular sieve adsorbent, the capacity of adsorbing low-sulfur fluoride is greatly reduced. In this embodiment, the sulfur hexafluoride raw gas has a high humidity, and is subjected to a process of removing most of moisture by the silica gel adsorbent in the four-stage silica gel adsorption tower 19, further drying by the alumina gel adsorbent in the alumina gel adsorption tower 20, and then blowing air by the diaphragm compressor 21 to enter the high-pressure adsorption unit. Under the condition of high pressure, further removing moisture by using a first-level alumina gel adsorbent, removing trace water by using a 5A molecular sieve, and ensuring that the subsequent 13X, CUCL and F-03 molecular sieve adsorbents have stronger adsorption capacity on low fluoride; removing CO2 with 13X molecular sieve adsorbent, removing CO with CUCL molecular sieve adsorbent, and adsorbing CO₂The adsorption of CO is not interfered mutually, and the sequence can be interchanged; further treating with F-03 molecular sieve adsorbent to obtain sulfur fluoride compound such as SF₂、SF₄、S₂F₂、S₂F₁₀Etc. and fluorooxysulfur compounds, e.g. SOF₂、SOF₄、SO₂F₂And adsorbing, and finally, rectifying in a rectifying tower.

Referring to fig. 8, in step S8, the rectification unit includes a first-stage rectification tower 28, a second-stage rectification tower 29, and a third-stage rectification tower 30, wherein the step of removing impurities by rectification includes:

controlling the tower top temperature of the first-stage rectifying tower 28, the second-stage rectifying tower 29 and the third-stage rectifying tower 30 to be-3 ℃ to-5 ℃, and controlling the tower bottom temperature to be 0 ℃ to 2 ℃; thereby obtaining the electronic grade product.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.