KR20030012750A - The Burner of Soot for Optical Fiber - Google Patents

Abstract

PURPOSE: A burner for manufacturing optical fiber preform is provided, which is characterized by containing seven burner unit, having four concentric circles each. Accordingly, the burner improves deposition efficiency due to increase of reaction area of SiCl4 and gives soots with uniformed shape. CONSTITUTION: The burner for manufacturing optical fiber preforms contains seven burners. Each burner unit comprises four concentric circles, wherein SiCl4, H2, Ar, and O2 gas are flown in the center(the first), second, third and fourth layer, respectively. The burner, having a structure of six burners around one burner, sprays SiCl4 through seven SiCl4 nozzles, and the reaction area of SiCl4 gas is increased, which results in 30% increase in deposition efficiency of SiO2 compared with a burner unit comprising four concentric circles.

Description

Burner device for manufacturing optical fiber base material {The Burner of Soot for Optical Fiber}

In the present invention, when producing an optical fiber base material, SiCl 4 is injected into the center of the optical fiber base material manufacturing burner composed of concentric circles, H2 gas is injected into the tube which is the second concentric circle in the cross section, and Ar gas is applied to the tube which is the third concentric circle in the cross section. In the cross section, the oxygen is injected into the tube, which is the fourth concentric circle, and the flame is turned on. In the oxyhydrogen flame, the SiCl4 gas is oxidized into SiO2 particles containing thermal energy. These SiO2 particles are deposited while releasing energy by hitting a rotating target surface.

At this time, in order to increase the efficiency of converting SiCl4 into SiO2, the contact area of SiCl4 gas with H2 and O2 flames in the flame should be increased. In the existing technology, the burner cross section is concentric, and SiCl4 gas, which is the main reaction source of glass particles, is injected only to the center of the burner, so the contact area with H2 and O2 flames around it is low, resulting in low reaction efficiency. In order to increase the reaction efficiency, SiCl4 glass raw material is injected into the center of the four concentric circles with the burner composed of four concentric circles in the cross section.The second layer flows H2 gas and the third layer is Ar gas and the fourth layer from the center. The layer flows O2 or forms a plurality of concentric circles out of the fourth layer to increase deposition efficiency. The fifth layer is Ar, the sixth layer is H2, the seventh layer is Ar, and the eighth layer is O2 gas. In order to further increase the deposition efficiency, a 12-layer burner, a 16-layer burner, or a 20-layer burner is used by repeating the gas arrays of the 5th to 8th layers. It is used, and byproducts thereof cause a problem of forming moisture inside the reaction chamber.

In theory, the theoretical formula is

SiCl4 + 2H2 + O2 → SiO2 + 4HCl

The chemical formula in the actual process

SiCl 4 + 4H 2 + 2O 2 SiO 2 + 4HCl + 2H ₂ O. The water formed in this way causes the glass particles to stick to the inner wall of the muffle, and in the case of coasuit, a large amount of Cl2 should be added during dehydration.

In order to solve the above problems, the present invention expands the contact area in the flames of H2 and O2 by injecting SiCl4 gas, which previously flowed only into the center of the burner, into a plurality of nozzles, and also in the H2 and O2 flames of the SiCl4 gas. It is the first object of the present invention to increase the diffusion in SiCl4 to increase the reaction of SiO2 to SiO2. At this time, if several burners produce SiO 2 particles by chemical reaction, and SiO 2 is generated independently to deposit SiO 2 on the target surface, it is impossible to obtain an optical fiber base having a certain shape such as outer diameter nonuniformity and outer surface bending. Therefore, SiCl 4 injected from a plurality of nozzles is made of SiO 2 and is a stable deposition on the surface of the soot to obtain a certain shape of the soot is a second object of the present invention.

By making seven small burners with four concentric cross sections and surrounding six burners around one burner, SiCl4 nozzles are sprayed through the four small concentric burner center tubes. It becomes a dog. When SiCl4 is injected through seven nozzles, the flames of seven burners are gathered into one to form a stable flame shape.SiCl4 injected from the center of each burner expands the contact area with H2 and O2 flames. The diffusion coefficient at is also high, increasing the reaction. At this time, the center diameter of the small burner is larger than 1 / √7 times the center diameter of the burner when SiCl 4 flows only to the center of the burner. In addition, since the present invention exhibits a high reaction efficiency at a lower ratio of H 2 and O 2 gas flow rates than the conventional one, it is possible to solve problems such as water content inside the soot or adhesion of glass powder inside the muffle.

1 is a basic four-layer concentric burner cross section

Figure 2 is a raw material multiple nozzle burner cross section

Figure 3 is a raw material multiple nozzle, double flame burner

<Description of Main Parts of Drawing>

1: SiCl4 nozzle part of burner 2: H2 gas nozzle part of burner

3: Ar gas nozzle part of burner 4: O2 gas nozzle part of burner

5: Multi-nozzle burner hood 6: Nozzle part for double flame of multi-nozzle burner

Hereinafter, described in detail by the accompanying drawings as follows.

1 shows a four concentric burner. A small burner is shown which flows SiCl4 gas in the center, H2 gas in the second layer, Ar gas in the third layer, and O2 gas in the fourth layer.

FIG. 2 shows a new, stable burner structure by arranging the six burners of FIG. 1 around one burner of FIG. 1, thus converting SiCl 4 to SiO 2 in a burner of seven SiCl 4 nozzles. The resulting SiO2 particles are stably attached to the soot surface and the soot growth is uniform, so that the distance between the burner tip and the soot surface is at least 3.5 times the diameter of the burner with seven SiCl4 nozzles.

Figure 3 is again made around the burner of Figure 2 to form a layer having four concentric circles in the first outer layer, Ar gas in the first outer layer, H2 gas in the second outer layer, Ar gas in the third outer layer, H2 gas was allowed to flow to the outermost layer.

At this time, the four layers added to the outside end length is longer than the inner seven burner group ends, the length is suitable for 1.5 to 3.5 times the diameter of the circle that binds the seven burner groups together.

SiCl4 sprayed from 7 burners can stabilize SiO2 deposition on the surface of the soot by controlling the distance between the burner end and the surface of the soot, but the flame is more stable by making the combustion layer of the inverted surface with the 7 burner outside. And soot deposition becomes easy.

As described above, in the existing burner, only SiCl 4 is injected, but in the present invention, the injection is divided into seven and H 2 gas, Ar gas, and O 2 gas are injected around each SiCl 4 nozzle in the H 2, O 2 flame of SiCl 4 gas. Increasing the contact area and increasing the diffusion of SiCl4 to increase the reaction efficiency to SiO2, in the existing burner to generate more than twice the amount of H2 gas and O2 gas compared to the chemical formula to increase the reaction efficiency, water was produced as a by-product, When burner of is used, even if 1.2 times of H2 gas and O2 gas is used, the reaction efficiency and deposition efficiency is 1.3 times that of existing and there is no moisture generation.

Claims (2)

Burner for the optical fiber base material, characterized in that the four concentric burner components as shown in FIG. The burner for an optical fiber base material further comprising a gas injection port having four to eight cross-sections concentrically outward from the burner of claim 1.