JPH0152332B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for bundling and fixing porous glass capillary tubes for fluid separation, and more particularly, to a method for bundling and fixing porous glass tubes for fluid separation, and in particular, a method for bundling and fixing porous glass tubes for fluid separation. The present invention relates to a method of forming a fitting part.

The scope of application of membrane separation means is increasingly expanding with the development of new separation membranes, but in order to withstand long-term use under high-temperature conditions, they must be made of inorganic materials, such as metals or ceramics. A plate-shaped sintered membrane or a tubular membrane has been developed. On the other hand, it is well known that separation membranes are combined to form a modular structure, but in order to make the device more compact, it is necessary to form the above-mentioned inorganic material into a material suitable for the modular structure, and the applicant has been considering this for some time. It's layered. As a result, we achieved a holographic fiber type module consisting of a large number of porous glass tubes bundled into a cylindrical shape and housed in a pressure vessel, which we previously disclosed (Japanese Patent Application Laid-Open No. 119402/1983). FIG. 1 is an explanatory view of the main parts of the above-mentioned device, and both ends of the porous glass tube 1 are bundled by bundle attachment plates 2A and 2B made of adhesive or the like. Of both open ends, the lower left side in the drawing is sealed by the bundle attachment plate 2A, and the upper right side in the drawing penetrates the bundle attachment plate 2B, and the open end faces the back side (opposite side) thereof. Also, a mixed fluid introduction pipe 3 is connected to the bundle attachment plate 2A.
is connected to a porous or perforated dispersion tube 4.
The unit shown in FIG. 1 is housed in a casing (not shown). Therefore, for example, when a mixed gas consisting of a large molecular gas and a small molecular gas is pressurized into the device through the introduction tube 3, it is distributed and diffused from the inside of the dispersion tube 4 to the outside, passing through the gap in the porous glass tube 1. Disperse as if passing through. Since the porous glass tube 1 is penetrated by pores of about 10 to 200 Å, small molecule gases in the mixed gas enter the tube through these gaps and are further collected from the back side of the bundle plate 2B. , while large molecular gases pass through the bundle of porous glass tubules 1 . Therefore, if these gases are recovered independently from separate exhaust ports provided in the casing (not shown), the separation of the large molecule gas and the small molecule gas is completely completed.

Although the apparatus and separation procedure are outlined above, such separation membrane modules have been found to be suitable for the separation of gaseous bodies (eg, separation of hydrogen gas from water gas). However, the separation of gaseous bodies
The separation membrane module must be able to withstand the above conditions sufficiently, as it is often carried out in extremely high-temperature environments of over 200°C, and in some cases over 400°C. Excellent chemical stability is required. However, although porous glass tubes and dispersion tubes are made of inorganic materials and satisfy the above characteristics, there have been many problems with bundled plates. That is, since porous glass tubes are hollow fibers with an outer diameter of usually 2 mm or less, in order to bundle and fix them, a fixing agent that sufficiently penetrates into the gaps between the tubes and solidifies is required. In particular, on the side of the bundling plate 2A in FIG. 1, it is necessary to enter the hollow part of the glass tube and seal it, and a highly permeable adhesive is required. In order to bundle and fix the thin tubes, it is preferable to bring the circumferential surface of each thin tube into contact with the above-mentioned fixing agent. Furthermore, although organic adhesives are convenient as such fixing agents, they have a decisive weakness in heat resistance, and a glass adhesive with high heat resistance is desired. However, the porous glass tubes mentioned above exhibit a negative or extremely low positive thermal expansion coefficient, so using a general homogeneous glass adhesive with a high thermal expansion coefficient will prevent cracking or peeling during use. I'm worried about this, and I can't suddenly hire someone.

For this reason, adhesives are used that are made of powdered ceramics with a negative thermal expansion coefficient and glass powders with a positive thermal expansion coefficient, either in powder form or mixed with water or liquid paraffin to form a paste. A method is proposed. When this adhesive is placed on the part of the glass tube that is to be fixed and then bundled and fired, only the glass melts and softens, exhibiting fluidity, and coats the surface of the tube and the ceramic powder, and the ceramics adhere to each other. It can be achieved.
Therefore, the blending ratio of the adhesive can be selected depending on individual circumstances, but since the coefficient of thermal expansion of ceramics is generally around -60×10 ^-7 °C ^-1 , the coefficient of thermal expansion of the entire adhesive is determined by In order to sufficiently approximate the quality of glass tubules, the glass mixing ratio of 40
The percentage of ceramics in the adhesive tended to increase, with the percentage of ceramics increasing. As a result, the adhesive itself became porous, creating problems in terms of airtightness.

The present invention has been made in view of these circumstances, and it is an object of the present invention to provide a method for performing the above-mentioned bundling using a homogeneous adhesive material with good heat resistance and chemical stability.

However, the bundling method according to the present invention means that glass powder with an SiO ₂ content of 75% by weight or more (hereinafter simply referred to as %) and a coefficient of thermal expansion of 2×10 ^-6 °C ^-1 or less is placed in the part to be bundled. The gist is that the glass powder applied portion is sintered and fixed by heating to an extent that does not reach the softening temperature of the porous glass tube.

Glass powder was first considered as an inorganic adhesive that could replace organic adhesives, but because it is heated to a considerably high temperature in the usage environment,
It is necessary to prevent cracking or separation from the porous glass tube due to repeated heating and cooling. Therefore, it must have a coefficient of thermal expansion sufficiently close to that of the porous glass tube, and in addition, the porous glass tube must not soften or melt at the bonding treatment temperature, and there are various restrictions. It was hot. Therefore, the present inventors selected glass powders having various compositions and physical properties, formed bundle bonded plates by the method shown in FIG. 2, and compared and studied the workability and physical properties after production.

That is, in FIG. 2, press molds 6A and 6B having semicircular recesses are arranged on the upper part of the bottom mold 5 so that the semicircular recesses face each other, and the porous glass tubes 1 are bundled and inserted therein, and various glass powders 8 are inserted therein. Charge.
In this case, it is preferable that the peripheral surface of each porous glass tube be in contact with the glass powder. Place the upper regulating disc 7 on the press molds 6A, 6B, and press the press molds 6A, 6B while heating the glass powder 8.
Gradually push in the direction of the arrow. The glass powder enters the gap in the porous glass tube 1 due to its fluidity, and a portion of the glass powder also enters the hollow space through the lower open end of the tube 1, resulting in the state shown in FIG. 3, and remains in this state. By being sintered, it performs bundle bonding and at the same time becomes a bundle bonding board.

Regarding the bundled plates and porous glass tubes produced in this way, we examined whether they had softened, whether they were airtight, whether they would crack or peel due to repeated heating and cooling, and chemically we found that the SiO ₂ content was 75. % or more, and physically the coefficient of thermal expansion is 2×10 ^-6 ℃.
Using glass powder that satisfies the condition of ^-1 or less,
Moreover, in sealing, it was concluded that it is necessary to sinter the glass powders together and between the glass powder and the porous glass tube at a temperature that does not soften the porous glass tube. .

As a glass powder that satisfies the above conditions, first of all,
Mention may be made of porous glasses in which more than 75% is occupied by SiO ₂ . Although the method of manufacturing the above-mentioned glass does not matter, generally, glass manufactured by the following method is used.

(1) _SiO2 : 22-75%, _Na2O : _2-16 %, _B2O3 :
18-67%, _Al2O3 : 0-5%, _{ZrO2 :} 0-5
%, _TiO2 : After melting and forming borosilicate glass with a composition of 0 to 5% as a raw material,
When heated to 500-650°C to induce phase separation in the glass and the sodium borate-rich phase eluted with acid, a porous glass is formed that is composed of more than 75% SiO ₂ . The porous glass powder obtained by crushing this powder is basically the same as the porous glass tube, and its coefficient of thermal expansion is virtually the same, so it is ideal as a material for forming bundle plates. It is a thing.

(2) Si(OC ₂ H ₅ ) ₄ , Ti(OC ₃ H ₇ ) ₄ , Zr(OC ₄ H ₉ ) ₄ ,
A metal alcoholate such as Al(OC ₃ H ₇ ) ₄ is dissolved in alcohol, water and acid are added to it, and the resultant gel is heated at room temperature or at elevated temperatures to form a porous material. quality glass is obtained. Here, if Si alkolate is used as the main component of the metal alkolate, a porous glass with an SiO ₂ content of 75% or more will be obtained, and the above conditions will also be satisfied in terms of the coefficient of thermal expansion.

As the adhesive other than the above-mentioned porous glass, borosilicate glass having a SiO ₂ content≧75% and a coefficient of thermal expansion≦2×10 ⁻⁶ ° C. ⁻¹ can also be used as is. The borosilicate glass mentioned here contains a larger amount of SiO ₂ than the borosilicate glass mentioned in (1) above,
The three components of B ₂ O ₃ , Na ₂ O, and SiO ₂ are 90% or more or
Contains 90% or more of the two components B ₂ O ₃ and SiO ₂ , for example, SiO ₂ : 85-91%, B ₂ O ₃ : 5%,
Those having a composition of Na ₂ O: 0.2% and Al ₂ O ₃ : 3.8% both have a coefficient of thermal expansion of 2 × 10 ^-6 °C ^-1 or less and satisfy the conditions as an adhesive in the present invention. do. However, the coefficient of thermal expansion of borosilicate glass is often about 10 × 10 ^-7 °C ^-1 larger than that of porous glass, and it may not be able to withstand use conditions that involve rapid temperature changes. porous glass tube
It is preferable to heat the porous portion to a temperature below the softening point at 1000° C. or higher to make the porous portion non-porous and to make the coefficient of thermal expansion approach that of borosilicate glass before application. Alternatively, after impregnating the bonded part of the porous glass tube with a boric acid aqueous solution,
The coefficient of thermal expansion of the bonded portion can also be brought close to that of borosilicate glass in advance by drying and firing. The softening point of borosilicate glass is lower than that of porous glass, such as SiO ₂ : 91%, B ₂ O ₃ : 5%, Na ₂ O: 0.2%,
Al ₂ O ₃ with a composition of 3.8% softens at about 880°C, which is significantly lower than the softening temperature of porous glass (generally around 1300°C), and has the advantage of being able to perform bundling work in a liquid state. be.

Further, the porous glass capillary used in the present invention has the same composition as the above-mentioned porous glass and is formed into a capillary shape. Furthermore, what is the coefficient of thermal expansion in the present invention?
Determined from the average linear expansion coefficient at 300 to 600°C. The softening point is the temperature at which the viscosity of the glass body becomes 4.5×10 ⁷ poise.

Since the present invention is configured as described above, it is possible to easily fix any part of a bundle of porous glass tubes, and there is no risk of softening or melting the porous glass tubes during fixation, and moreover, the present invention can be used at high temperatures. Even if used for a long time or repeatedly in an environment, the fixed portion will not crack or peel, and airtightness can be safely maintained for a long period of time.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the main parts of the separating device, FIG. 2 is a sectional view showing the bundling method, and FIG. 3 is a sectional view of the main parts of the bundling section. 1...Porous glass tube, 2...Bundle attachment plate.

Claims (1)

[Scope of Claims] 1. A method of bundling and fixing thin tubes formed of porous glass, which method includes bundling the porous glass tubes, and having a SiO ₂ content of 75% by weight or more and a coefficient of thermal expansion of 2×. A porous glass characterized in that glass powder of 10 ^-6 ℃ ^-1 or less is applied to the part to be fixed, and the part to which the glass powder is applied is sintered and fixed by heating to an extent that does not reach the softening temperature of the porous glass tube. How to bundle tubules. 2 In claim 1, the glass powder is applied after the part of the porous glass tube where the porous glass tube is to be fixed is heated in advance to a temperature of 1000°C or higher but below the softening point to lose its porosity. A method for fixing porous glass tubes by sintering and fixing them.