KR101833882B1 - Method for separation of fluorinated gas using multi-stage gas separation process comprising high-selectivity hollow fiber membrane modules - Google Patents

Abstract

The present invention relates to a method for producing a hollow fiber membrane module, comprising the steps of: I) compressing a mixed gas containing a fluorinated gas and supplying the compressed gas to a first stage gas separation unit including a hollow fiber membrane module; II) separating the first concentrated gas and the first permeated gas in the first-stage gas separation unit; And III) supplying the first concentrated gas to the second stage gas separator including the hollow fiber membrane module, and separating the second concentrated gas and the second permeated gas.
According to the present invention, it is possible to recover fluorinated gas with high efficiency from a mixed gas containing fluorinated gas by using a multistage gas separation process of two or more stages including a hollow fiber membrane module having high selectivity of nitrogen with respect to fluorinated gas, And the amount of gas discharged toward the permeable gas can be greatly increased by controlling the stage cut of the multi-stage gas separation unit.

Description

[0001] The present invention relates to a method for separating fluorinated gas using a multi-stage gas separation process including a high-selectivity hollow fiber membrane module,

The present invention relates to a method for separating fluorinated gas using a multistage gas separation process including a hollow fiber membrane module having a high selectivity, and more particularly, to a method for separating fluorinated gas using a multistage gas separation process including a hollow fiber membrane module having a high selectivity, And a method for recovering and separating fluorinated gas with high efficiency using a multi-stage gas separation process.

Currently, the United States has withdrawn from the Kyoto Protocol, but in February 2002, the US Department of Energy led the US Climate Change Technology Program Program) has been established and has led research and investment on emission reduction and reuse of fluorocarbons. In addition, the US Environmental Protection Agency has been working with industry to successfully implement voluntary programs to reduce global warming gases, including sulfur hexafluoride (SF ₆ ). Recent US climate change technology programs have concluded that cryogenic capture and membrane separation techniques are more effective than conventional pressure swing adsorption techniques in the recovery and reuse of sulfur hexafluoride.

In 2003, Air Liquide in France installed a filtration system of sulfur hexafluoride on a pilot scale at a power IC manufacturing plant in a pilot scale. The gas produced in the process was 60% sulfur hexafluoride and 40% air , And then treated with two membrane systems to obtain 89% of sulfur hexafluoride recovery and 99% or more purity.

As a conventional technique for separating fluorinated gas such as sulfur hexafluoride, sulfur hexafluoride is selectively separated and recovered from a mixed gas containing a bentonite sulfur by using a gas separation membrane selected from a polyimide membrane, a carbon membrane or a zeolite membrane However, there is a problem in that it is difficult to separate and recover sulfur hexafluoride with high efficiency because sulfur hexafluoride is mixed in the gas permeating through the gas separation membrane and recovery loss of sulfur hexafluoride occurs (Patent Documents 1 and 2).

In addition, although a method using a multi-stage gas separation membrane is known, there is a disadvantage in that recovery gas is generated because the fluorinated gas flows out along with the diluent gas as a permeation gas of the gas separation membrane in the first stage. It is difficult to separate and recover them with high efficiency (Patent Documents 3 and 4).

Therefore, in the present invention, it is possible to collect and separate fluorinated gas with high efficiency according to various degrees of selectivity by using a multi-stage gas separation process of two or more stages including a hollow fiber membrane module having high selectivity of nitrogen to fluorinated gas. Thereby completing the invention.

Patent Document 1: JP-A-11-345545 Patent Document 2. Japanese Patent Application Laid-Open No. 2000-140558 Patent Document 3: JP-A-10-128034 Patent Document 4: JP-A-9-103633

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a hollow fiber membrane module having a high selectivity for nitrogen with respect to fluorine gas, And to provide a method for separating fluorinated gas from the mixed gas at a high efficiency and within 5% of the fluorinated gas concentration of the feed.

According to an aspect of the present invention, there is provided a method for producing a hollow fiber membrane module, including: (I) compressing a gas mixture containing fluorinated gas and supplying the compressed gas to a first stage gas separation unit including a hollow fiber membrane module; II) separating the first concentrated gas and the first permeated gas in the first-stage gas separation unit; And III) supplying the first concentrated gas to the second stage gas separator including the hollow fiber membrane module, and separating the second concentrated gas and the second permeated gas.

Mixed gas containing the fluoride gas is _{SF 6, NF 3, BF 3} , SiF 4, CF 4, C 2 F 4, C 2 F 6, C 3 F 8, C 4 F 10 , or N ₂ in the CHF ₃ gas Gas is mixed.

And the mixed gas containing the fluorinated gas is N ₂ / SF ₆ .

The material of the hollow fiber membrane is any one selected from the group consisting of polysulfone, polyimide, polyetherimide, polyamide, polyamideimide, polycarbonate, and cellulose acetate.

Wherein the hollow fiber membrane has an outer diameter of 300 to 400 mu m and an inner diameter of 150 to 250 mu m.

The hollow fiber membrane module is characterized in that the selectivity of N ₂ / SF ₆ is 50 to 150.

And the total stage cut of the first stage gas separation unit and the second stage gas separation unit is 0.12 to 0.51.

According to the present invention, it is possible to recover fluorinated gas with high efficiency from a mixed gas containing fluorinated gas by using a multistage gas separation process of two or more stages including a hollow fiber membrane module having high selectivity of nitrogen with respect to fluorinated gas, And the amount of gas discharged toward the permeable gas can be greatly increased by controlling the stage cut of the multi-stage gas separation unit.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process for separating a mixed gas containing fluorine gas using a two-stage gas separation process according to the present invention. FIG.
2 is a scanning electron microscope (SEM) image of a section of a hollow fiber membrane according to the present invention.
3 is a graph showing SF ₆ recovery rates according to the stage cuts of Experimental Examples 1 to 4;
4 is a graph showing the relationship between N ₂ / SF ₆ A graph showing the throughput (supply flow rate) of the mixed gas.

Hereinafter, the fluorine gas separation method using the multi-stage gas separation process including the high selectivity hollow fiber membrane module according to the present invention will be described in detail.

The present invention relates to a method for producing a hollow fiber membrane module, comprising the steps of: I) compressing a mixed gas containing a fluorinated gas and supplying the compressed gas to a first stage gas separation unit including a hollow fiber membrane module; II) separating the first concentrated gas and the first permeated gas in the first-stage gas separation unit; And III) supplying the first concentrated gas to the second stage gas separator including the hollow fiber membrane module, and separating the second concentrated gas and the second permeated gas. FIG. 1 shows a process of separating a mixed gas containing fluorine gas using a two-stage gas separation process according to the present invention.

In the present invention, fluorinated gas can be defined as a gas containing fluorine atoms, and SF ₆ , NF ₃ , BF ₃ , SiF ₄ , CF ₄ , C ₂ F ₄ , and C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₁₀ or CHF ₃ gas, among which sulfur hexafluoride (SF ₆ ) is a typical example. In this semiconductor process, N ₂ (nitrogen) gas is supplied as a diluent gas to the fluorinated gas and discharged in the form of a mixed gas. In the step I), the mixed gas containing fluorine gas is SF ₆ , NF ₃ , BF ₃ , SiF ₄ , CF ₄ , C ₂ F ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₁₀ or CHF ₃ gas mixed with N ₂ gas. Preferably, the mixed gas containing the fluorinated gas may be N ₂ / SF ₆ .

The gas separation is performed by the hollow fiber membrane module in the first and second gas separators. The material of the hollow fiber membrane may be polysulfone, polyimide, polyetherimide, polyamide, polyamide, Amide, polycarbonate, and cellulose acetate.

The hollow fiber membrane preferably has an outer diameter of 300 to 400 탆 and an inner diameter of 150 to 250 탆, because the selectivity of nitrogen to fluorine gas can be increased.

In the hollow fiber membrane module, the gas-permeable hollow fiber membrane is mounted in a vessel provided with a gas feed port, a permeate gas outlet port, and a non-permeate gas outlet port so that the gas supply side and the gas permeation side space of the hollow fiber membrane are spaced apart from each other In particular, when the hollow fiber membrane module is employed in the first stage gas separator and the second stage gas separator, the selectivity of N ₂ / SF ₆ is preferably 50 to 150. When the selectivity of N ₂ / SF ₆ is less than 50, it is difficult to keep the concentration of the exhaust gas within 5% of the introduced gas, and it is difficult to obtain a recovery rate of 95% or more at the stage cut of 0.4 or more. In addition, the hollow fiber membrane module having a selectivity of N ₂ / SF ₆ exceeding 150 has a disadvantage that it is difficult to produce the hollow fiber membrane module in reality.

The stage cut in the multi-stage gas separation process according to the present invention means the ratio of the flow rate of each permeate gas to each flow rate supplied to the first stage gas separation unit and the second stage gas separation unit. The total stage cut of the first stage gas separation unit and the second stage gas separation unit is preferably 0.12 to 0.51. If the total stage cut is less than 0.12, it is difficult to concentrate the concentration of the residual fluorinated gas because the amount of the exhaust gas is smaller than the introduction gas. If the total stage cut exceeds 0.51, the concentration of the residual fluorinated gas is easily concentrated, It is difficult to achieve the above.

Hereinafter, specific examples will be described in detail.

(Hollow fiber membrane module fabrication and single gas permeability test)

The hollow fiber membrane was adjusted to have an outer diameter of 400 m, an inner diameter of 250 m, and an effective membrane area of 1.24 m < ^{2 &gt};. The hollow fiber membrane module had a diameter of 1.5 inches, 12 inch. From the scanning electron microscope image of the cross section of the hollow fiber membrane of FIG. 2, it can be seen that a defect-free uniform hollow fiber membrane was produced. In addition, four types of sulfur hexafluoride in the supply pressure 0.5Mpa, using a hollow fiber membrane module (SF ₆₎ gas and nitrogen (N ₂₎ by measuring the gas permeance of each of N ₂ / SF ₆ selectivity of 51.31, 61.38, 81.55 of And 108.44, respectively.

( Experimental Example  1 to 4)

The selection of the N ₂ / SF ₆ also respectively 51.31, 61.38, using the 81.55 and 108.44 in four types of the hollow fiber membrane module N _2: SF ₆ = 50: target 50 in the mixed gas was carried out for one-stage separation process , And detailed experimental results thereof are shown in Tables 1 to 4, respectively.

Feed gas flow rate (ccm) 5816 3100 2165 1495 1170 Concentrated gas flow rate (ccm) 5150 2450 1540 900 600 SF ₆ concentration (%) 56.42 62.67 69.03 80.45 92.47 N ₂ concentration (%) 43.58 37.33 30.97 19.55 7.53 Sum 100.00 100.00 100.00 100.00 100.00 Transmission gas flow rate (ccm) 666 650 625 595 570 SF ₆ concentration (%) 3.82 4.14 4.50 4.94 6.12 N ₂ concentration (%) 96.18 95.86 95.50 95.06 93.88 Sum 100.00 100.00 100.00 100.00 100.00 SF ₆ Recovery (%) 99.13 98.28 97.42 96.10 94.08 Stage Cut 0.11 0.21 0.29 0.40 0.49

Feed gas flow rate (ccm) 6522 2570 1550 960 339 Concentrated gas flow rate (ccm) 5920 2050 1090 590 169 SF ₆ concentration (%) 55.29 62.55 70.41 79.64 95.16 N ₂ concentration (%) 44.71 37.45 29.59 20.36 4.84 Sum 100.00 100.00 100.00 100.00 100.00 Transmission gas flow rate (ccm) 602 520 460 370 170 SF ₆ concentration (%) 2.28 2.50 2.98 3.77 5.90 N ₂ concentration (%) 97.72 97.50 97.02 96.23 94.10 Sum 100.00 100.00 100.00 100.00 100.00 SF ₆ Recovery (%) 99.58 99.00 98.25 97.12 94.13 Stage Cut 0.09 0.20 0.30 0.39 0.50

Feed gas flow rate (ccm) 6627 3155 1718 995 419 Concentrated gas flow rate (ccm) 5920 2530 1180 600 214 SF ₆ concentration (%) 56.16 62.28 72.12 81.39 93.17 N ₂ concentration (%) 43.84 37.72 27.88 18.61 6.83 Sum 100.00 100.00 100.00 100.00 100.00 Transmission gas flow rate (ccm) 707 625 538 395 205 SF ₆ concentration (%) 2.14 2.29 2.77 3.32 5.75 N ₂ concentration (%) 97.86 97.71 97.23 96.68 94.25 Sum 100.00 100.00 100.00 100.00 100.00 SF ₆ Recovery (%) 99.55 99.10 98.28 97.38 94.42 Stage Cut 0.11 0.20 0.31 0.40 0.49

Feed gas flow rate (ccm) 6006 2825 1375 790 264 Concentrated gas flow rate (ccm) 5400 2290 950 480 136 SF ₆ concentration (%) 55.92 61.85 72.13 81.49 93.18 N ₂ concentration (%) 44.08 38.15 27.87 18.51 6.82 Sum 100.00 100.00 100.00 100.00 100.00 Transmission gas flow rate (ccm) 606 535 425 310 128 SF ₆ concentration (%) 1.18 1.38 1.83 2.26 4.95 N ₂ concentration (%) 98.82 98.62 98.17 97.74 95.05 Sum 100.00 100.00 100.00 100.00 100.00 SF ₆ Recovery (%) 99.76 99.48 98.88 98.24 95.24 Stage Cut 0.10 0.19 0.31 0.39 0.48

3, the recovery rate of SF ₆ according to the stage cuts of Experimental Examples 1 to 4 is graphically shown. As shown in Tables 1 to 4 and FIG. 3, when the stage cut is about 0.1 to 0.5, the SF ₆ recovery rate is about 95% The results show that the higher the selectivity of N ₂ / SF _6, the higher the SF ₆ recovery rate in the same stage cut.

(Example)

A two-stage separation process was carried out using the hollow fiber membrane module (N ₂ / SF ₆ selectivity of 81.55) according to Experimental Example 3, and the detailed performance results are shown in Table 5.

Feed gas flow rate (ccm) 11072 6324 3642 2439 1630 First stage Transmission gas flow rate (ccm) 704 695 672 646 590 SF ₆ concentration (%) 1.82 2.13 2.36 2.50 2.82 N ₂ concentration (%) 98.18 97.87 97.64 97.50 97.18 Sum 100.00 100.00 100.00 100.00 100.00 Second stage Transmission gas flow rate (ccm) 638 579 470 363 240 SF ₆ concentration (%) 2.02 2.56 3.29 4.31 6.14 N ₂ concentration (%) 97.98 97.44 96.71 95.69 93.86 Sum 100.00 100.00 100.00 100.00 100.00 Concentrated gas flow rate (ccm) 9730 5050 2500 1430 800 SF ₆ concentration (%) 57.09 62.53 72.17 83.74 98.77 N ₂ concentration (%) 42.91 37.47 27.83 16.26 1.23 Sum 100.00 100.00 100.00 100.00 100.00 SF ₆ Recovery (%) 99.54 99.07 98.29 97.41 96.18 Stage Cut First stage 0.06 0.11 0.18 0.26 0.36 Second stage 0.06 0.09 0.13 0.15 0.15 Sum 0.12 0.20 0.31 0.41 0.51

4 is a graph showing the relationship between N ₂ / SF ₆ From Table 5 and FIG. 4, it can be seen that the SF ₆ recovery rate is slightly higher in the two-stage separation process than in the one-stage separation process of the same selectivity, It can be seen that the throughput at the cut of about 0.1 was about twice that of the cut at about 0.1 and the throughput was about four times that of the stage cut of about 0.5.

Therefore, according to the present invention, it is possible to recover fluorinated gas from a mixed gas containing fluorinated gas with high efficiency by using a multistage gas separation process of two or more stages including a hollow fiber membrane module having high selectivity of nitrogen with respect to fluorinated gas, And the amount of gas discharged toward the permeable gas can be greatly increased by controlling the stage cut of the multi-stage gas separation unit.

Claims (7)

I) compressing a mixed gas containing fluorinated gas and supplying the compressed gas to a first stage gas separation unit including a hollow fiber membrane module;
II) separating the first concentrated gas and the first permeated gas in the first-stage gas separation unit; And
III) supplying the first concentrated gas to a second stage gas separation unit including a hollow fiber membrane module, and separating the second concentrated gas into a second concentrated gas and a second permeated gas,
The mixed gas containing the fluorinated gas is N ₂ / SF ₆ ,
The hollow fiber membrane module has a selectivity of N ₂ / SF ₆ of 50 to 150,
Wherein the total stage cut of the first stage gas separation unit and the second stage gas separation unit is 0.12 to 0.51. delete delete The method according to claim 1, wherein the material of the hollow fiber membrane is any one selected from the group consisting of polysulfone, polyimide, polyetherimide, polyamide, polyamideimide, polycarbonate, and cellulose acetate . The method for recovering fluorinated gas according to claim 1, wherein the hollow fiber membrane has an outer diameter of 300 to 400 탆 and an inner diameter of 150 to 250 탆. delete delete

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