JPH01208338A - Production apparatus for matrix for optical fiber - Google Patents

Abstract

PURPOSE:To provide the title apparatus so designed that when a glass material is to be hydrolyzed in the presence of flame in a reaction vessel and a porous matrix is to be grown, an exhaust means comprising an exhaust pipe having an opening of specific shape is installed, thereby effecting greater efficiency for the discharge of suspended granular glass and obtaining the title matrix free from foaming in high yield. CONSTITUTION:An exhaust means is installed in a reaction vessel 11 so that the end 17 i.e., an exhaust port of an exhaust pipe 16 is so constructed that its sectional shape is circular, ellipsoidal or rectangular, as desired, and its sectional area fall between 10 and 60% of the are of the side ABCD where the exhaust pipe 16 is present. Thence, glass material (e.g., SiCl4) and such gases as H2, O2 and Ar are fed, via e.g., a concentric multitubular burner 12, into the reaction vessel where the mixture is combusted to perform hydrolysis in a flame 13 to produce granular glass and a porous matrix 15 is grown on a starting material or core rod each rotatable with a means 14 along with quick and efficient discharge of suspended granular glass through the exhaust pipe 16 having said exhaust port 17 without suspension in the vessel 11, thus suppressing the adherence of said granular glass to the inner wall of the vessel 11 or the matrix 15.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an apparatus for producing a glass base material for original fibers, and more specifically to an apparatus for producing a porous glass base material using a flame hydrolysis reaction. be.

[Conventional technology]

Generally, in the production of a porous glass base material using a flame hydrolysis reaction, combustion gas, glass raw materials, etc. are mixed and ejected from a burner 82 in a reaction vessel 81 using a device R11 as shown in FIG. The granular glass produced by the hydrolysis reaction of the glass raw material in the oxyhydrogen flame 83 is deposited on a rotating starting material or mandrel, and is deposited on the rotating starting material or mandrel, and is deposited on the porous base material 85t- in the direction of the rotation axis 84. A growing method is used. At this time, the granular glass that has not been deposited as the porous base material 85 is suctioned from inside the reaction vessel 81 through the exhaust pipe 86 and guided to -waste gas treatment fc11188.

[Problem to be solved by the invention]

In conventional manufacturing methods, 50-80% of the granular glass produced is deposited as a porous matrix. Therefore, 20 to 50% of the generated granular glass is not deposited as a porous matrix but is discharged. For example, if the synthesis rate of the base material is 4777 minutes, granular glass will be discharged into the reaction vessel from 0.8 to 211 minutes/minute. This undeposited granular glass floats inside the reaction vessel and is discharged from the exhaust pipe, but if it cannot be discharged smoothly and fills the reaction vessel, it may have a negative impact on the porous base material that is the product. affect That is, if floating particulate glass in the reaction vessel adheres to the surface of the porous base material, it will cause bubbles to be generated in the glass when the porous base material is turned into transparent galanic in a subsequent step. Furthermore, if floating matter adheres to the starting material Rondo, air bubbles will be generated and the product will be defective. Furthermore, if floating particulate glass thickly adheres to the inner wall of the reaction vessel, it takes time to clean it, which causes a decrease in the operating rate of the equipment. As described above, if the nine-grain glass is not deposited on the porous base material and is not evacuated quickly and the reaction vessel is filled, various adverse effects may occur. This becomes more noticeable and becomes an important problem as the synthesis speed of the base material increases.

In order to forcibly exhaust the floating particulate glass inside the reaction vessel, a method of increasing the suction power of the exhaust gas may be considered, but this may cause greater disturbance of the gas flow inside the reaction vessel. . In that case, a shadow I# will also be exerted on the flame of the burner, causing the flame to become turbulent. When the flame is turbulent, the efficiency of depositing granular glass onto the porous matrix deteriorates. Furthermore, in order to form a refractive index distribution in the radial direction of the porous base material, Go
When adding elements such as t's, there is a problem that the refractive index distribution formed becomes disordered. In fact, if the exhaust volume is doubled than before, the synthesis yield of the porous base material will be 70% to 65%.
When the flame was observed, it was clear that the flame turbulence had increased.

The present invention is a reaction vessel for forming a porous matrix T-S by depositing granular glass produced by flame hydrolysis, etc., and includes an improved exhaust means that can quickly and efficiently exhaust undeposited granular glass. The purpose of this device is to provide a device that can efficiently produce a high-quality base material for fibers.

[Means to solve the problem]

As a result of various studies, the inventors have found that floating particulate glass in the reaction vessel can be efficiently exhausted without increasing the exhaust volume by making the exhaust port widen from the exhaust pipe toward the inside of the reaction vessel. I found out.

The present invention includes a burner in a reaction vessel that generates granular glass by flame hydrolyzing a gaseous glass raw material;
In an apparatus for producing a base material for an original fiber, the apparatus comprises a rotation means for gripping and rotating a starting material or a mandrel for growing a porous base material by depositing the granular glass on the surface thereof, and an exhaust means, The exhaust means is an apparatus for producing a base material for original fiber, characterized in that the exhaust pipe has a shape in which the opening widens toward the inside of the reaction vessel.

To specifically explain the non-invention with reference to the drawings, FIG. 1 is a schematic sectional view showing an embodiment of the present invention, and FIG. 2 is a view taken along arrows a-a' of the first cause. Middle 11 is a reaction container,
12 is a burner, 13 is a flame, 14 is a rotating shaft, 15 is a porous base material, and 18 is a waste gas treatment device.
Although the structure is similar to the conventional structure shown in the figure, the feature of the present invention is in the exhaust pipe 16, and the end (exhaust port) 17 of the exhaust pipe 16 that opens into the reaction vessel 11 is The end portion is shaped so as to widen toward the direction. The cross-sectional shape of the end portion 17 may have various shapes such as circular, oval, and rectangular, but as shown in FIG. 2, the cross-sectional area of the end portion 17 (the shaded area in the figure) The most efficient exhaust is possible if the exhaust pipe is within the range of 10 to 60% of the area of the side A'B CD.

[Effect]

The effect of the present invention that rapid exhaust can be realized by adopting the shape of the exhaust port that widens from the exhaust pipe side toward the inside of the reaction container is that the wide exhaust port sucks in a wide range of gases in the reaction container evenly. It is thought that this is because of this. In other words, as shown in Figure 9, in the case of a normal exhaust port, the area where the air is strongly sucked is limited to a narrow area in front, and the suction force in other areas is small, and the flow is rather distorted as shown by the arrow in Figure 9. The mixture is circulated in the reaction vessel 81 as shown in FIG. On the other hand, in the case of the wide exhaust port of the present invention, since a wide area inside the reaction container is sucked evenly, the gas flow inside the reaction container is uniform toward the exhaust port 17, as shown by the arrow in FIG. It becomes close to. For this reason,
The granular glass discharged into the reaction container 11
1, and is quickly discharged outside from the exhaust port 17.

The cross-sectional area of the open end of this exhaust port is the exhaust port 1 of the reaction vessel.
Area of I111411 plane cr) 10 S60 X O
We have found that being within this range is optimal. 10%
This is because if the diameter is smaller, the effect of the large diameter is lost as described above, and if it is made larger than 60%, the entire exhaust force is reduced.

〔Example〕

Example 1 A porous base material was manufactured under the following conditions using the apparatus for manufacturing a porous base material for original fiber according to the present invention shown in FIG. The area of the side surface of the reaction vessel on the exhaust port side is 4500 m2'
As shown in Figure 4 (&), the shape of the exhaust port is a trumpet-shaped exhaust pipe with a circular cross section with a diameter l of 1001 mm, and the tip of the exhaust pipe increases in diameter toward the inside of the reaction vessel, and the side has 10 scratches. The tip of the opening in the reaction vessel was circular with a rear radius of 17 degrees, and the cross-sectional area was 900 m2, that is, 20% of the area of the side A of the vessel. Centripetal 4]! 1 glass raw material SiC/4 is placed in the first boat at the center of the tube burner! / minute, 10 H2 on the second boat! /min, krf51/min to the 3rd port, and 02i2 (1/min flow rate) to the 4th port. A porous base material with an outer diameter of 800 mm was synthesized at a synthesis speed of 297 minutes, but the yield was Most of the granular glass that was released without being deposited on the porous matrix was discharged from the exhaust pipe, and the granular glass that adhered to the container surface was less than 1% of the ejected glass. , the obtained porous matrix also has a smooth surface;
This was dehydrated and sintered to vitrify it, and no air bubbles were observed in the base material.

Comparative Example 1 Using the device of the above example, only the exhaust port was made of a cylindrical type without a trumpet-shaped part and the diameter j was Ion as shown in Fig. 4 (bl), and all other conditions were the same as in Example 1. We attempted to synthesize the base materials and compared the differences depending on the shape of the exhaust pipe.

The yield of the porous matrix was 70% as in Example 1, but the released granular glass was thickly attached to the inner wall of the reaction vessel, and was estimated to account for about 10% of the total released granular glass. Ta. In addition, many protrusions were observed on the surface of the synthesized porous base material, which appeared to be a layer of granular glass floating in the reaction vessel. When this base material was vitrified, 10 square meters of air bubbles were found within the glass.

Although the above embodiment uses an exhaust cap whose wIT surface has a circular opening, similar effects can be expected with other rectangular or elliptical exhaust caps.

As another embodiment of the present invention, Fig. 6 (ml, (bl) Fig. 7 (IL), (bl, Fig. 8 (tortoise), (b) K cross-sectional view f: Show f! Shape of eel ridges Of course, even if the exhaust pipe has a shape other than that shown in the drawings, the present invention includes the use of an exhaust pipe with a wide opening inside the reaction vessel.

〔Effect of the invention〕

As explained above, the invention makes it possible to efficiently discharge floating particulate glass in the reaction vessel by providing an exhaust pipe whose end diameter widens toward the inside of the reaction vessel. may form a layer on the inner wall of the reaction vessel,
It reduces the cost of equipment maintenance because it prevents particles from adhering to the porous base material, and it also improves productivity by producing a porous base material that does not generate bubbles when vitrified. It is an effective device for improvement.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a specific example of the device of the present invention, FIG. 2 is a view taken in the &-a' direction of FIG. 1, and FIG. Figure 4 (a) is an explanatory diagram of the exhaust pipe used in the example of the present invention, the same figure (bl is an explanatory diagram of the exhaust pipe of the comparative example, Figure 5 (&I, (b), Figure 6 (a) , (b
) and FIG. 7 (ILI, (1)) are vjT plane views showing various exhaust pipe shapes in the present invention. Fig. 8 is a schematic sectional view explaining the conventional device, and Fig. 9 is a schematic sectional view of the conventional device.
FIG. 3 is an explanatory diagram of gas flow within the conventional device shown in the figure.

Claims (2)

[Claims] (1) A burner that generates granular glass by flame hydrolyzing a gaseous glass raw material in a reaction vessel, and a starting material or mandrel for depositing the granular glass on the surface of the burner and growing a porous base material. In the apparatus for producing an optical fiber preform, the apparatus comprises a rotating means for gripping and rotating the base material, and an evacuation means, wherein the evacuation means has a shape in which the evacuation pipe has an opening that widens toward the inside of the reaction vessel. An optical fiber base material manufacturing device characterized by: (2) The optical fiber according to claim 1, wherein the cross-sectional area of the end of the opening is within a range of 10 to 60% of the area of the side surface of the reaction vessel where the exhaust pipe is located. Manufacturing equipment for base materials.