JPS6329565B2 - - 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 1000 Å 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, a technique is required to hermetically seal the ends of the hollow fibers.
Conventionally, heat-resistant separation membrane devices using porous glass have not been put to practical use because sealing materials suitable for this purpose have not been available.

The present inventors have actively investigated sealing materials and have developed a sealing material that solves all of the conventional problems in terms of thermal expansion coefficient, bonding temperature, heat resistance, etc. for sealing porous glass. We have 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 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 the partition wall is made of ceramics with a negative coefficient of thermal expansion at 1000℃.
This is a separation membrane device characterized by comprising a mixture with an inorganic binder having the following softening point.

As a representative example of porous glass in the present invention, 95
There are high silicate glasses that contain more than a weight percent of SiO ₂ , with a pore volume of around 30 percent and an average pore diameter of 10-3000 Å. 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.
SiO ₂ 22-75% by weight, B ₂ O ₃ 18-67% by weight, Na ₂ O2 - 16% by weight, Al ₂ O ₃ 0
-5% by weight of borosilicate glass, 0-5% by weight of ZrO ₂ , 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 made into thin tubes or hollow fibers by melting borosilicate glass having the above composition in a double crucible and directly spinning it, 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.

The materials constituting the partition walls in the present invention are ceramics with a negative expansion coefficient and an inorganic bond with a softening point of 1000°C or less. An example of a ceramic having a negative expansion coefficient is a ceramic obtained by firing Li ₂ O, Al ₂ O ₃ and SiO ₂ in a molar ratio of 1:1:1.5 at 1400° C. for 5 hours. In this case, the coefficient of thermal expansion of ceramics is 300℃.
The average value at 600°C was -60×10 ^-7 1/°C. On the other hand, as an inorganic bond with a softening point of 1000℃ or less, the thermal expansion coefficient of the well-known Pyrex glass or aluminosilicate glass is (30-60) ×
10 ^-7 1/℃. For example _SiO2 57%,
_{Al2O3 15} %, _{B2O3 5} %, MgO7%, CaO10%,
BaO6% aluminosilicate glass is 52×
It exhibits a coefficient of thermal expansion of 10 ^-7 1/℃, and SiO ₂ 80.8%,
_{Al2O3 2.3} %, _{Fe2O3 0.03} %, _{B2O3 12.5} %,
Pyrex glass with Na ₂ O 4.0% and K ₂ O 0.4% is
It 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/℃. 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. The present invention uses a mixture of ceramics having a negative coefficient of thermal expansion and an inorganic bonding material having a softening point of 1000 DEG C. or less as a partition wall material that satisfies these limiting conditions. In this case, for example, a powder mixture of ceramics and an inorganic binder with a particle size of 10 to 150 micrometers is mixed with 55 to 90 parts by weight of ceramics and an inorganic binder.
When used at a ratio of 55 to 90 parts by weight, only the inorganic binder melts and softens at the bonding temperature and wets the porous glass hollow fibers and ceramic powder. A partition wall in which the powder is dispersed and porous glass fibers are penetrated is obtained. 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.

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 packings, and 12, 13, 14, 15 are bolt holes for fastening the flange 19 of the cylindrical member 1 and the end 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 around the porous tube 7 almost parallel to the axis to constitute the hollow fiber bundle 4, and one end of the porous glass hollow fibers penetrates the partition wall 5 and opens, and the other end passes through the partition wall 5 and opens. 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 tube 7 is shown in FIG. 1, there is no particular restriction as long as the fluid flow path is maintained near the central axis of the hollow fiber bundle 4, and for example, a mesh tube 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. Such a structure is particularly recommended for the separation membrane device of the present invention used at high temperatures.
Even if the partition wall, the cylindrical moving member, and the flange are made of different materials and have different coefficients of thermal expansion, sealing can be achieved reliably. That is, the seal between the outer fluid chamber 21 and the inner fluid chamber 20 of the porous glass hollow fiber is guaranteed 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. 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.

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 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 are partitioned, and the partition wall is made of ceramic having a negative thermal expansion coefficient and heated to 1000°C.
A separation membrane device comprising a mixture with an inorganic binder having the following softening point. 2. According to claim 1, the cylindrical container comprises a cylindrical member having a flange at the end and an end plate, and the partition wall is sandwiched between the flange of the cylindrical member and the end plate. Separation membrane device. 3. 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. 4. 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. 5. The separation membrane device according to claim 1, wherein the porous glass hollow fibers are cross-layered to form the hollow fiber bundle. 6. 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.