JPS63107802A - Method for producing oxygen-enriched air - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for producing a large amount of oxygen-enriched air with an oxygen concentration of about 20 to 40 inches while maintaining a negative pressure outside the hollow fiber using fibers.

(Prior art) In recent years, oxygen-enriched air with an oxygen concentration of about 20 to 401 is produced by membrane separation as an alternative to air for oxidation, fermentation, blast furnace injection, combustion assistance, and waste liquid treatment aeration in chemical processes. Attempts have been made to use evaporated air. The present applicant also disclosed in JP-A No. 61-101225 that a hollow fiber having an inner diameter of 350 μm or more and a permeation performance of 0.5 Nrrl/ν・H・嬔性 or more was used, and the inside of the hollow fiber was subjected to negative pressure under specific conditions. We proposed a method to produce oxygen-enriched air while maintaining

Although this is an excellent production method using oxygen-enriched air that does not reduce performance or permeate air volume, it has the following problems in practical use. (1) Even if a fan or blower is used, it is difficult to supply enough raw air to the center of the hollow fiber bundle.
The central portion of the hollow fiber bundle becomes a dead zone, requiring an unnecessarily large membrane area.

(2) A special structure is required to supply sufficient raw material air to the center of the hollow m-thin bundle.

(Means for Solving the Problems) The present invention provides a practical method for producing oxygen-enriched air that solves the above-mentioned problems. This is a method for producing oxygen-enriched permeated air by uniformly supplying oxygen to the inside of the hollow fiber and selectively permeating it from the inside to the outside of the hollow fiber.

In the method of the present invention, the hollow fiber has an inner diameter of 800 or more and a permeability of 0.5Ni//-H-Kjl/c.
Hollow fibers are used that are equal to or greater than yj and satisfy the following formula.

The permeation performance of the hollow fiber used in the present invention is expressed using the following equation.

However, FC: Transmission performance (Nd/♂・H-Ky/ctA)
Q: Permeated air amount (NH1/H) Pl: Primary side air pressure (Ky/m abs) P2: 2
Next side air pressure (Ky/ci abs) D = inner diameter of hollow fiber (m) L: length of hollow fiber (m) When producing a large amount of oxygen-enriched air with an oxygen concentration of about 20 to 40 g The separation property of the selective oxygen permeable membrane is 2.0 to 3.0, but the ratio of the oxygen to nitrogen permeability coefficients is only 1,000 min. Should be selected. This is because - In general, the separation performance and permeation performance of materials have contradictory properties, and membrane materials with good separation performance do not have good permeation performance. Therefore, the membrane material is determined based on the balance between separation performance and permeation performance, taking into consideration the relationship with the application. Therefore, the selective oxygen permeable membrane used for the purpose of the present invention has a ratio of oxygen to nitrogen permeability coefficients of 2.0 or more and a permeability of 0.5 Nrl/rl-
Any material can be used as long as it has H, Ky, /crA or higher, but from the viewpoint of the required oxygen concentration of the enriched air obtained and the separation operation, preferably the permeability coefficient ratio is 2.5.
The above shows a transmission performance of 1.5 Nrl/rl·H and NVi.

A membrane having a permeability of less than 0.5 Nrl/dH-9/- cannot produce enriched air with the desired concentration under low pressure operating conditions.

The material should preferably have a large oxygen permeability coefficient, and the membrane thickness should be as thin as possible and durable, since the amount of permeation is inversely proportional to the membrane thickness.

As for the form of the membrane, any of asymmetric membrane, homogeneous membrane, and composite membrane can be used, but in particular, a thin polymer membrane is uniformly formed on the inner surface of a hollow fiber membrane-like porous support to prevent it from penetrating into the pores. Composite hollow fiber membranes are preferably used because they have high permeability, selectivity of 2.0 or more, can be made into extremely thin membranes of 0.5 μm or less, and are durable. The required performance of the material from which the microporous hollow fibers of such a composite hollow fiber membrane are to be formed is to prevent breakage of the thin polymer film coated on its inner surface so as not to substantially penetrate into the pores. However, it is sufficient that the material has sufficient mechanical strength and physical properties to facilitate handling, and in this sense, polyvinyl alcohol, aromatic polysulfone, polyamide, polyether ether lactone, etc. can be used. Particularly preferred are aromatic polysulfones, which have various advantages such as excellent hollow fiber moldability and good heat resistance.

Regarding polymer thin film components, polydimethylsiloxane,
Polyorganosiloxanes such as polydiphenylsiloxane and polymethylphenylsiloxane, and various polymers such as poly-4-methylpentene-1, polytetrafluoroethylene% furfuryl alcohol dendritic cellulose acetate, cellulose triacetate, and poly-4-vinylpyridine. Although polymers having selective separation permeability can be used, polysiloxane-based polymers are particularly suitable polymers in the sense that they have the largest oxygen permeation rate constant among all polymers.

Furthermore, silicone rubber whose strength and physical properties are improved by three-dimensionally crosslinking such chain polyorganosiloxane with a crosslinking catalyst has further improved strength and physical properties of polymer thin films made of chain polyorganosiloxane. Therefore, it has the great advantage of being able to be made into a thin film. The length must be 0 and the inner diameter is 80
less than 0 μm and the above parameters are 1. Hollow A-fibers with a diameter exceeding OX 10' have a large flow resistance within the hollow fibers, and the power consumption of the fan that supplies raw air becomes large, resulting in poor economic efficiency.

(Function) The present invention has the effect of producing a large amount of enriched air with an oxygen concentration of 20 to 40 inches using hollow fibers with high permeability under operating conditions at low pressure levels even with a membrane module with a simple structure. However, such an effect is completely unexpected from conventional knowledge. The reason for this effect is that by using large diameter hollow fibers with an inner diameter of 800 μm or more, and by adjusting the length to a length that satisfies the above-mentioned specific conditions,
Since the flow resistance of air passing through the membrane can be reduced to a negligible level with respect to the differential pressure between the primary air pressure and the secondary air pressure, the power of the supply air fan can be reduced and energy-saving young fruit can be produced. 0 (Example) Example 1 and Comparative Example 1 Aromatic polysulfone (product new polysulfone: P
-1700: Mix and dissolve 100 parts by weight of Union Carno (manufactured by Ido), 10,000 parts by weight of polyvinylpyrrolidone, and 500 parts by weight of dimethylformamide, which is a common solvent for them, and after sufficiently defoaming, discharge from an annular nozzle. After molding, passing through a water bath while supplying water to the hollow part to remove dimethylformamide, and drying, 100 parts by weight of aromatic polysulfone and 100 parts by weight of polyvinylpyrrolidone are finally mixed extremely uniformly. On the other hand, a room-temperature curing silicone rubber (trade name: Silpot 184W/C: manufactured by Dow Corning) and 1/1 of that were obtained.
A 10 weight silicone solution was prepared by dissolving 0 amount of curing catalyst in n-pentane.The 10 weight silicone solution thus prepared was prepared.

Approximately 3 Q on the inner surface side of the aforementioned non-porous hollow fiber membrane base material.
Supply the silicone solution for about 3 minutes at a supply rate of mj/min, then drain the silicone solution by natural dripping, and then remove the air for 1 minute.
It was allowed to pass for about 1 minute at a linear speed of 5 m/sea.

Thereafter, crosslinking treatment was carried out at 100°C X I HR, and then the polyvinylpyrrolidone was extracted and removed by immersion in 60°C ethanol for 16 hours. By such a method, the porous hollow fiber membrane-like base material made of aromatic polysulfone and its inner surface are finally formed so as not to substantially penetrate into the pores of the inner surface, and to form the hollow fibers. Circumferential direction of the inner surface of the thread,
and an inner diameter of 50 mm, which is well formed with a thin silicone rubber film formed with extremely uniform thickness in both the fiber axis direction.
0Iin, 800AB11000P111200μm,
A composite hollow optical spectrometer M film with a length of 1 m was obtained. A large number of these hollow fiber membranes were bundled and fixed with epoxy resin so that both ends were open, a module with a membrane area of 100 mm was created, and the outside of the hollow fibers and the inside of the housing were sucked with a Roots blower to remove the hollow fibers. The results of measuring the influence of the inner diameter on separation performance and permeation performance are shown in I-1.

In addition, a plot of the above results is shown in Figure 1.O c-L2 From the above example, the parameter ``is determined as follows.In other words, assuming that the amount of air permeating to the outside of the hollow fiber is 0, the flow inside the hollow fiber is is a laminar flow state, and the flow resistance is expressed by the equation 0.

q=πxDxLxFc x (PH-Pz)□■However, -o Pressure loss (Ky/crA)Fc Membrane permeability performance (Nrrf/rl-H-KVctA)D
Inner diameter of hollow fiber (m) L Length of hollow fiber (m) Pl Primary pressure (KVc!Aaba)Pz
Secondary pressure (Ky/c!Aabs) μ viscosity
(ky/m-S) U flow velocity (m/S) gc Gravity conversion factor (9,8kP-m7S2-K
y) If the supply air amount on the primary side is Q (Ni/H), then Q
=10q□□■ is the preferred supply amount, and air is supplied according to the formula.

The viscosity of air at a temperature of 20°C is 18 x 10-60-
Substituting 6kf into equation 0 and combining it with equation (■) yields equation (■).

Table 2 shows the correction coefficients when comparing the results calculated by formula (1) with the results in Table 1 shown in Example 1 and Comparative Example 1.

From the above results, if the correction coefficient is in the range of 0.73 to 0.77 and 0.75 is adopted as the average value, then equation (2) can be replaced with equation 0.

The hollow fibers having four types of inner diameters used in Example 1 and Comparative Example 1 have the differences between the primary pressure and the secondary pressure as shown in Table 3.

Table 3 By substituting the results of Table 3 into Equation 0 and rearranging them, the parameters can be summarized in Table 4, taking into account operating conditions and hollow fiber specifications (transmission performance, inner diameter, length).Table 4 (Effects of the Invention) As described above, the method of the present invention makes it possible to economically produce oxygen-enriched air from air by selecting the inner diameter and length of the hollow fibers based on the permeation performance of the membrane, operating conditions, etc. This is an extremely useful method in practice.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the flow resistance of the inner diameter of hollow fibers. Patent applicant: FJ Ware Co., Ltd. Agent: Patent Attorney Doboku Taken

Claims (1)

[Claims] In a method for producing oxygen-enriched permeated air by maintaining a negative pressure outside the hollow fiber and selectively permeating air from the inside to the outside of the hollow fiber, the inside diameter of the hollow fiber is is 800μm or more, and the transmission performance is 0.5Nm^3/m
A method for producing oxygen-enriched air characterized by using hollow fibers having a value of ^2·H·Kg/cm^2 or more and satisfying the following formula. L^2/D^3<(1.0×10^9)/Fc However, Fc: Transmission performance (Nm^3/m^2・H・Kg/c
m^2) D: Inner diameter of hollow fiber (m) L: Length of hollow fiber (m)