JPS646802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a separation membrane device that performs a separation operation by selectively permeating a specific component in a gas or liquid using porous glass hollow fibers.

Conventionally, separation membranes mainly made of organic polymer materials have been used in separation membrane devices, but none have been satisfactory in fields where heat resistance, corrosion resistance, chemical resistance, etc. are required. For example, after steam reforming heavy oil to obtain a mixed gas of hydrogen and carbon monoxide,
Ethanol is produced from the raw material gas obtained by hydrogen concentration.
In the process of synthesizing ethylene glycol and the like, a separation membrane module that selectively permeates hydrogen gas at high temperatures of 300 to 400°C is desired.

Separation membrane materials and inorganic porous materials that can withstand such high temperatures are attracting attention, and materials made by sintering fine powder of metal or ceramics are being considered. However, these sintered materials have relatively large pore diameters of 1000A or more, and although they can be made into large-diameter tubes, they cannot be formed into thin tubes or hollow fibers. Since the surface area per unit volume is small, the processing capacity per unit volume of the device is small, and it is not put into practical use.

On the other hand, the porous glass of the present invention can withstand temperatures up to 850°C, has a pore diameter of 10-3000 angstroms, and can range from hollow tubes with an outer diameter of about 2 mm to hollow fibers with an outer diameter of 20 microns. It has the advantage of being freely moldable. In order to assemble such porous glass tubes or hollow fibers (hereinafter collectively referred to as porous glass hollow fibers) into a separation membrane device, it is necessary to use a technology to manufacture a partition wall with the ends of the hollow fibers hermetically sealed. A technology is required to seal the gap between the container and the cylindrical container at high temperatures. Porous glass hollow fibers made of high silicate glass have a small thermal expansion coefficient of (-10 to +5) x 10 ^-7 1/℃, so the thermal expansion of the partition wall that penetrates and seals the porous glass hollow fibers. The rate will be similarly small. On the other hand, metals, plastics, glass fiber reinforced plastics, etc. that make up cylindrical containers and bolts have a coefficient of thermal expansion of (100 to 1000) x 10 ^-7 1/°C, so for example, the temperature in the range of 100 to 500°C It has been difficult to seal between the partition wall and the cylindrical container or the end plate in an environment where the temperature changes.

The inventors of the present invention actively investigated a method for sealing a partition wall, constructed a cylindrical container from a cylindrical member with a flange at the end, and an end plate, inserted the partition wall between the flange and the end plate, and bolted the container. We also developed a separation membrane device with a structure fixed by a spring, and arrived at the present invention.

That is, in the present invention, a hollow fiber bundle made of porous glass hollow fibers having an outer diameter of 2 mm or less and an average pore diameter of 10 to 3000 angstroms is housed in a cylindrical container, and at least one end of the hollow fiber bundle is The porous glass hollow fibers are opened through the partition wall, and the partition wall partitions a fluid chamber communicating with the inside of the porous glass hollow fibers and a fluid chamber communicating with the outside of the porous glass fibers. and that the cylindrical container is composed of a cylindrical member having a flange at the end and an end plate, and that the partition wall is sandwiched between the flange of the cylindrical member and the end plate and fixed by bolts and springs. This is a separation membrane device with special features.

As a representative example of porous glass in the present invention, 95
There are high silicate glasses containing more than weight percent _SiO2 , with a pore volume of around 30 percent and an average pore diameter of 10-3000A. This type of porous glass is manufactured by utilizing the phase separation phenomenon of borosilicate glass in a specific composition range, and the composition varies depending on the composition.
_SiO2 22-75 weight percent, _{B2O3 18-67} weight percent _{, Na2O2-16} weight percent, _Al2O30
-5% by weight of borosilicate glass, 0-5% by weight of ZrO ₂ and 0-5% by weight of TiO ₂ is melted and formed, and when heat treated at a temperature of 500-650℃, phase separation occurs and it becomes soluble in acids. The phase separates into a phase rich in sodium borate and a phase rich in nearly insoluble silicon dioxide. It is then treated with acid to elute the sodium borate-rich phase, which consists primarily of silicic acid;
A porous glass having an average pore diameter of 10 to 3000 Å can be obtained.

The porous glass hollow fiber in the present invention is a hollow fiber with an outer diameter of 2 mm or less, and the ratio of the inner diameter to the outer diameter is selected to be 40-90%. Such porous glass hollow fibers can be formed into thin tubes or hollow fibers by melting borosilicate glass having the above composition in a double crucible and spinning it directly, or by heating and drawing out the end of a previously prepared tube. It is manufactured by heat-treating and acid-treating the molded product.

Examples of materials constituting the partition walls in the present invention include ceramics having a negative expansion coefficient and inorganic composites having a softening point of 1000°C or less. Examples of ceramics with negative expansion coefficients include LiO ₂ ,
Examples include ceramics obtained by firing at 1400° C. for 5 hours with a molar ratio of Al ₂ O ₂ and SiO ₂ of 1:1:1.5. In this case, the average coefficient of thermal expansion of ceramics at 300℃-600℃ is -60×
It was 10 ^-7 1/℃. On the other hand, examples of inorganic composites having a softening point of 1000 DEG C. or less include the well-known Pyrex glass or aluminosilicate glass having a coefficient of thermal expansion of (30-60) ^{.times.10.sup.} -7 1/.degree. For example, SiO ₂ 57%, Al ₂ O ₃ 15%, B ₂ O ₃ 5%, MgO 7%,
Aluminosilicate glass with 10% CaO and 6% BaO exhibits a coefficient of thermal expansion of 52×10 ^-7 1/℃, and
_SiO2 80.8%, _{Al2O3 2.3} %, _{Fe2O3 0.03} %,
Pyrex glass containing 12.5% B ₂ O ₃ , 4.0% Na ₂ O, and 0.4% K _{2 O} exhibited a coefficient of thermal expansion of 32×10 ^-7 1/°C.

The porous glass in the present invention exhibits a coefficient of thermal expansion with a negative or extremely low positive value, and the value is (-10 to
+5)×10 _-7 1/°C. Therefore, the material for the partition walls that seal the ends of such porous glass hollow fibers is similarly required to have a low coefficient of thermal expansion. Furthermore, the bonding temperature is limited to 1000°C or less due to the limit of the deformation temperature of the pores of porous glass. Furthermore, if the operating temperature of the separation membrane device is, for example, 400°C, the softening point of the partition wall material must be higher than 400°C.
Furthermore, the material of this partition wall is required not only to adhere and hold the porous glass hollow fibers, but also to have airtightness and sealability against the fluid to be separated. An example of a barrier wall material that satisfies these limiting conditions is a mixture of ceramics with a negative coefficient of thermal expansion and an inorganic composite with a softening point of 1000°C or less. In this case, for example, the particle size of ceramics and inorganic composite is 10
- When a powder mixture of 150 micrometers is used in a ratio of 55 to 90 parts by weight of ceramics and 55 to 90 parts by weight of inorganic binder, only the inorganic binder melts and softens at the bonding temperature, forming porous glass hollow fibers. Since the ceramic powder is wetted with the ceramic powder, the ceramic powder is dispersed in the inorganic binder which is then cooled, and a partition wall is obtained in which the porous glass fibers penetrate. This type of bonding operation is carried out by preparing a mold for the partition wall to be molded, and placing a mixed powder of ceramics and an inorganic binder and the ends of porous glass hollow fibers in this mold, but the bonding temperature If the fluidity of the inorganic binder is not sufficient, it is also effective to apply a hot press method.

In the present invention, the spring used to fix the partition wall between the flange and the end plate is a coil spring or a plate spring (disc spring). By using springs, the partition wall, flanges, and end plates are completely sealed despite the difference in thermal expansion coefficients of the bolts.
There are no particular restrictions on the material of the spring, but 300 to 400
Inconel
I can give you sus631.

Next, the structure of the separation membrane device of the present invention will be explained according to the drawings, but the drawings show specific examples of the present invention, and the present invention is not limited by these drawings.

FIG. 1 is an axial sectional view showing a specific example of the present invention. A hollow fiber bundle 4 is housed in a cylindrical container consisting of a cylindrical member 1 having a flange 19 at the end and end plates 2 and 3. The porous glass hollow fibers constituting the hollow fiber bundle 4 are connected to a partition wall 5. It passes through and opens on the left side. On the other hand, the other end of the porous glass hollow fiber is embedded in the block 6 and closed.

Further, the partition wall 5 is arranged to partition a fluid chamber 20 communicating with the inside of the porous glass hollow fiber and a fluid chamber 21 communicating with the outside of the hollow fiber. A porous tube 7 is arranged near the central axis of the hollow fiber bundle 4, and the porous glass hollow fibers are laminated around this porous tube 7. The porous tube 7 has an opening in the tube wall, and the fluid flow path 8 in the porous tube communicates with the outside of the porous glass hollow fiber through this opening. Also, the partition wall 5
is sandwiched between the cylindrical member 1 and the end plate 2. Here, 9, 10, 11 are gaskets, and 12, 13, 14, 15 are bolt holes for fastening the flange 19 of the cylindrical member 1 and the plate 2 or 3.

When performing a separation operation using the apparatus shown in FIG.
The liquid enters the hollow fiber bundle 4 through the opening in the porous glass hollow fiber, flows through the fluid chamber 21 outside the porous glass hollow fiber, and is discharged through the opening 17 in the end plate 3. The raw material fluid is hollow fiber bundle 4
While flowing, a part of the raw material fluid permeates from the outer circumferential side of the porous glass hollow fibers to the hollow side, passes through the hollow flow path of the porous glass hollow fibers, penetrates the partition wall 5, and flows inside the hollow fibers. The fluid enters the fluid chamber 20 communicating with the fluid chamber 20 and is taken out through the opening 18 of the end plate 2.

FIG. 2 shows a perspective view of a hollow fiber bundle of the embodiment of the invention shown in FIG. Porous glass hollow fibers are arranged approximately parallel to the axis around the porous tube 7 to constitute the hollow fiber bundle 4, and one end of the porous glass hollow glass penetrates the partition wall 5 and opens, and the other end opens through the partition wall 5. The end is shown embedded in block 6 and closed.

In Figures 1 and 2, an example is shown in which the porous glass hollow fiber is open at one end and closed at the other end. It is also possible to adopt a structure in which the fibers are open at both ends. In this case, it is used when a first fluid is passed inside the porous glass hollow fiber and a second fluid is passed outside to perform mass exchange through the membrane wall. Although the porous pipe 7 is shown in FIG. 1, there is no particular restriction as long as the fluid flow path is maintained near the hollow axis of the hollow fiber bundle 4, and for example, a mesh pipe may be used. Further, when the outer diameter of the porous glass hollow fibers is relatively large and the porous glass hollow fibers themselves are strong, it is also possible to construct a fluid flow path in the vicinity of the central axis using only the porous glass hollow fibers. By providing the fluid flow path in this manner, the raw material fluid can flow in the radial direction of the hollow fiber bundle, which has the advantage of lower pressure loss than when flowing in the axial direction. Furthermore, since the flow rate distribution in the axial direction becomes uniform, the separation operation can be performed efficiently.

Further, FIG. 1 shows a structure in which the partition wall 5 is sandwiched between the flange 19 of the cylindrical member 1 and the end plate 2.

FIG. 3 is an enlarged view of a portion where the flange 19 and end plate 2 of FIG. 1 are fixed by bolts and springs.
In FIG. 3, the bolt 22 passes through the bolt hole 13 of the flange 19 and the bolt hole 12 of the end plate 2, and the nut 2 is inserted between the coil spring 24 and washers 25 and 26.
It is fixed by 3. The coil spring 24 is the third
In the figure, it is arranged between the flange 19 and the head of the bolt 22, but it may also be arranged between the end plate 2 and the nut 23. The action of the coil spring 24 ensures that the outer fluid chamber 21 and the inner fluid chamber 20 of the porous glass hollow fiber are sealed despite expansion and contraction during temperature raising and lowering operations.

FIG. 2 shows an example in which porous glass hollow fibers are arranged substantially parallel to the axis. The method of arranging the porous glass hollow fibers can be selected depending on the type of separation operation, the properties of the raw fluid, the flow direction of the fluid, and the physical properties of the porous glass hollow fibers. For example, it may be preferable to arrange the porous glass hollow fibers so as to cross each other and stack them, or it is also possible to wrap them spirally around a central axis and stack them.

In addition, spacers in the form of powder, string, fiber, or cloth are placed in the gaps between the porous glass fibers to firmly hold the porous glass fibers. It is also possible to have a structure with In addition, in order to use a granular spacer, the hollow fiber bundle 4 is housed in a cylindrical container and the rear end plate 3 is
The granules are filled into the container from the side and the hollow fiber bundle is fixed. Further, a fibrous spacer may be formed each time the hollow fibers are wound around the porous tube 7 by laminating, for example, solid fibers on the wound layer to fix the hollow fiber bundle.

[Brief explanation of drawings]

FIG. 1 shows an axial cross-sectional view of a specific example of the separation membrane device of the present invention. 2 is a perspective view of a hollow fiber bundle of the separation membrane device shown in FIG. 1, and FIG. 3 is a partially enlarged view of FIG. 1. DESCRIPTION OF SYMBOLS 1... Cylindrical member, 2, 3... End plate, 4... Hollow fiber bundle, 5... Partition wall, 6... Block, 7... Porous pipe, 20... Fluid chamber communicating with the inside, 21...
Fluid chamber communicating with the outside, 22... Bolt, 23...
...Natsuto, 24...Coil spring.

Claims (1)

[Claims] 1. The outer diameter is 2 mm or less and the average pore diameter is 10 to 10.
A hollow fiber bundle made of porous glass hollow fibers having a thickness of 3000 angstroms is housed in a cylindrical container, and at least one end of the hollow fiber bundle is opened through a partition wall, and the partition wall is opened. A cylindrical member configured to partition a fluid chamber communicating with the inside of the porous glass hollow fiber and a fluid chamber communicating with the outside of the porous glass hollow fiber, and the cylindrical container having a flange at an end; A separation membrane device comprising an end plate, the partition wall being sandwiched between the cylindrical member flange and the end plate and fixed by bolts and springs. 2. The separation membrane device according to claim 1, wherein a fluid flow path communicating with the outside of the porous glass hollow fibers is provided near the central axis of the hollow fiber bundle. 3. The separation membrane device according to claim 1, wherein the porous glass hollow fibers are arranged substantially in parallel to form the hollow fiber bundle. 4. The separation membrane device according to claim 1, wherein the porous glass hollow fibers are cross-layered to form the hollow fiber bundle. 5. The separation membrane device according to claim 1, in which a granular or fibrous spacer is arranged in the gap between the porous glass hollow fibers to fix the hollow fiber bundle.