JP2018123022A - Multiple pipe burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiple pipe burner capable of accumulating soot efficiently.SOLUTION: In a multiple pipe burner 1 including a raw material gas pipe 11 for sending raw material gas therethrough, a combustible gas pipe 15 for sending combustible gas therethrough, and first combustion supporting gas pipes 13 for sending combustion supporting gas therethrough, an injection port 11A of the raw material gas pipe 11 and an injection port 13A of the first combustion supporting gas pipes 13 are arranged inside an injection port 15A of the combustible gas pipe 15, and the injection port 13A of the first combustion supporting gas pipes 13 are arranged so as to enclose the injection port 11A of the raw material gas pipe 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a multi-tube burner and is suitable for manufacturing, for example, an optical fiber preform.

  When manufacturing an optical fiber preform or the like, a manufacturing method is used in which a raw material gas is sprayed together with a flame and glass particles obtained by the combustion reaction are deposited on a target. Examples of such production methods include VAD (Vapor-phase Axial Deposition), OVD (Outside Vapor Deposition), and MCVD (Modified Chemical Vapor Deposition). Glass particles are called soot.

  As a burner used in such a method for producing a porous glass deposit, a burner that oxidizes a silicon-containing compound that does not contain a halide is disclosed in Patent Document 1 below. A plurality of injection regions are provided on one surface of the burner of Patent Document 1 below.

  Specifically, a first region for injecting a mixed gas of octamethylcyclotetrasiloxane, which is a raw material gas, and oxygen, which is a combustible gas, is disposed at the center of the burner outlet, and a second region for injecting nitrogen is provided. It is provided so as to surround the first region. Further, a plurality of third regions for injecting oxygen, which is an auxiliary combustion gas, are provided at predetermined intervals around the second region, and a plurality of injecting a mixed gas of methane, which is an inflammable gas, and oxygen, which is an auxiliary combustion gas. The fourth region is provided outside the third region at a predetermined interval.

Japanese National Patent Publication No. 11-510778

  By the way, when the amount of source gas increases, the flame spreads when the combustion reaction occurs, and soot tends to diffuse due to the flame. In the burner of the above-mentioned patent document 1, the 1st field which injects the mixed gas of source gas and auxiliary combustion gas is provided in the outermost peripheral side of the injection mouth of a burner. For this reason, there is a concern that soot spreads to the outer peripheral side of the first region due to the flame that spreads widely, and the amount of soot deposited on the target decreases.

  On the other hand, it is considered that soot diffusion outside the first region can be reduced by increasing the flow rate of the mixed gas of the raw material gas and the auxiliary combustion gas injected from the first region. However, when the flow rate of the mixed gas is increased, the temperature of the soot is lowered due to the gas flow, and there is a concern that the amount of soot deposited may be reduced without the soot adhering to the target.

  Therefore, the present invention provides a multi-tube burner that can deposit soot efficiently.

  In order to solve the above problems, a multi-tube burner of the present invention includes a raw material gas pipe for flowing a raw material gas, a flammable gas pipe for flowing a flammable gas, and a first auxiliary flammable gas pipe for flowing a flammable gas. The injection port of the raw material gas pipe and the injection port of the first auxiliary combustible gas pipe are disposed inside the injection port of the combustible gas pipe, and the injection port of the first auxiliary combustible gas pipe is the raw material gas. It is arranged to surround the injection port of the tube.

According to such a multi-tube burner, the raw material gas is injected inside the auxiliary combustion gas, and the combustible gas is injected so as to surround the auxiliary combustion gas and the raw material gas. For this reason, the auxiliary combustion gas acts like a wall that suppresses the diffusion of the raw material gas, and the raw material gas is easily confined inside the auxiliary combustion gas. Accordingly, it is possible to reduce the outward diffusion of the soot. Thus, it is possible to suppress the soot from diffusing, and to suppress a decrease in the amount of soot deposited on the target.
Further, since the injection port of the first auxiliary combustible gas pipe and the injection port of the raw material gas pipe are separately arranged, the gas flow rate can be set individually. Therefore, even if the spread of the flame increases as the amount of the raw material gas increases, the flow rate of the auxiliary combustion gas injected from the injection port of the first auxiliary combustion gas pipe is set so that the soot does not diffuse outward due to the expanded flame. Can be adjusted. Thus, the flow rate of the combustible gas does not need to be increased so much that the soot temperature is lowered by the gas flow, so that it is difficult for the soot to adhere to the target. As a result, it is possible to suppress a decrease in the amount of soot deposited on the target.
Thus, according to the multi-tube burner of the present invention, the amount of soot deposited per unit raw material gas can be increased. Thus, soot can be deposited efficiently.

  The second auxiliary combustible gas pipe further flows a second auxiliary combustible gas pipe, and an injection port of the second auxiliary combustible gas pipe is an inner side of the injection port of the combustible gas pipe. It is preferable that it is arranged outside the injection port.

  In this way, the combustible gas can be burned more efficiently, and the temperature of the soot deposited on the target can be controlled. Moreover, since the auxiliary combustion gas doubles the raw material gas, the raw material gas can be more easily confined inside the auxiliary combustion gas.

  In addition, a first seal gas pipe for flowing a seal gas is further provided, the injection port of the raw material gas pipe is disposed inside the injection port of the first seal gas pipe, and the injection port of the first auxiliary combustion gas pipe is The first sealing gas pipe is preferably disposed so as to surround the injection port.

  In this way, the raw material gas can be prevented from diffusing outward, and the reaction position between the raw material gas and the combustible gas injected from the raw material gas injection port and the combustible gas injection port is sealed. It can be adjusted by the gas flow rate or the like. Therefore, it is possible to further reduce the soot from diffusing to the outside, and to deposit the soot on an appropriate range of the target.

  The ratio of the flow rate of the raw material gas flowing through the raw material gas tube and the flow rate of the auxiliary combustible gas flowing through the first auxiliary combustion gas tube is preferably within a range of 0.35 to 0.75.

In this way, the flow rate of the raw material gas changes within a predetermined range when the deposition efficiency is 100% when all Si atoms contained in the raw material become soot (SiO ₂ ) and adhere to the target. However, the deposition efficiency of 50% or more can be ensured.

  The ratio is preferably in the range of 0.4 to 0.75.

In this way, the flow rate of the raw material gas changes within a predetermined range when the deposition efficiency is 100% when all Si atoms contained in the raw material become soot (SiO ₂ ) and adhere to the target. However, it is possible to ensure a deposition efficiency of 70% or more.

  In addition, the injection port of the raw material gas pipe is disposed inside the injection port of the first auxiliary combustion gas pipe, and the injection port of the first auxiliary combustion gas pipe extends over the entire circumference of the injection port of the raw material gas pipe. It is preferable to surround.

  In this way, the injection port of the first auxiliary combustion gas pipe surrounds the injection port of the raw material gas pipe, so that the injection region of the injection port of the first auxiliary combustion gas pipe surrounds the outer periphery of the injection port of the raw material gas pipe over the entire circumference. It will be. For this reason, the diffusion of the raw material gas can be further suppressed by the auxiliary combustion gas, the combustion can be made uniform in the circumferential direction, and the soot generation can be made uniform in the circumferential direction.

  In addition, a plurality of the first auxiliary combustion gas pipes are provided, and the injection ports of the plurality of first auxiliary combustion gas pipes are arranged at predetermined intervals around the injection port of the raw material gas pipe. It is also possible. In this case, the production of the multi-tube burner can be facilitated.

  As described above, according to the present invention, a multi-tube burner capable of efficiently depositing soot is provided.

It is a figure which shows a mode that the injection port of the multi-tube burner which concerns on 1st Embodiment of this invention was seen from the injection side of gas. It is a figure which shows a mode that the injection port of the multi-tube burner which concerns on 2nd Embodiment of this invention was seen from the injection | emission side of gas. 3 is a graph showing the relationship between the gas flow rate and the deposition efficiency in Example 1. It is a graph which shows the relationship between the flow velocity of gas in Example 2, and deposition efficiency.

  Hereinafter, preferred embodiments of a multi-tube burner according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a view showing a state where an injection port which is an injection port of a multi-tube burner according to the present embodiment is viewed from the gas injection side. As shown in FIG. 1, the multi-tube burner 1 includes a raw material gas pipe 11, a first seal gas pipe 12, a plurality of first auxiliary combustible gas pipes 13, a plurality of second auxiliary combustible gas pipes 14, and a combustible gas. The gas tube 15 and the second seal gas tube 16 are provided. In FIG. 1, for easy visual recognition, the raw material gas pipe 11, the first seal gas pipe 12, the respective first auxiliary gas pipes 13, the respective second auxiliary gas pipes 14, the combustible gas pipes 15, the first Although the two-seal gas pipe 16 is hatched, the hatched line does not indicate the cross section of the pipe.

  The source gas pipe 11 is a pipe through which source gas flows, and a gas supply device is connected to the end of the source gas pipe 11 opposite to the injection end side via a connecting pipe. Examples of the raw material of the raw material gas include octamethylcyclotetrasiloxane. When silicon-containing compounds that do not contain halides such as octamethylcyclotetrasiloxane and hexamethyldisiloxane are used as a raw material gas, hydrochloric acid is not generated by the combustion reaction of the raw materials, so the halides are contained. Silicon-containing compounds that are not preferred are preferred as source gases.

  The first seal gas pipe 12 is a pipe through which seal gas flows, and a gas supply device is connected to the end of the first seal gas pipe 12 opposite to the injection end side through a connecting pipe. As seal gas, inert gas, such as nitrogen and argon, is mentioned, for example.

  The plurality of first auxiliary combustion gas pipes 13 are pipes through which auxiliary combustion gas flows. The end of the first auxiliary combustible gas pipe 13 opposite to the injection end side is connected to a gas supply device via a connecting pipe. Examples of the auxiliary gas include oxygen.

  The plurality of second auxiliary combustion gas pipes 14 are pipes through which auxiliary combustion gas flows. An end portion of the second auxiliary combustible gas pipe 14 opposite to the injection end side is connected to a gas supply device via a connecting pipe. The first auxiliary gas pipe 13 and the second auxiliary gas pipe 14 may be connected to the gas supply device via a common communication pipe, or connected to the gas supply device via separate connection pipes. May be. However, when the first auxiliary gas pipe 13 and the second auxiliary gas pipe 14 are connected to the gas supply device via separate connecting pipes, the first auxiliary gas pipe 13 and the second auxiliary gas pipe 14 are connected. The flow rate and type of auxiliary combustion gas can be changed.

  The combustible gas pipe 15 is a pipe through which a combustible gas flows, and a gas supply device is connected to the end of the combustible gas pipe 15 opposite to the injection end side through a connecting pipe. Examples of the combustible gas include hydrogen and methane.

  The second seal gas pipe 16 is a pipe through which seal gas flows, and a gas supply device is connected to the end of the second seal gas pipe 16 opposite to the injection end side through a connecting pipe. The first seal gas pipe 12 and the second seal gas pipe 16 may be connected to the gas supply apparatus via a common communication pipe, or connected to the gas supply apparatus via separate connection pipes. Also good. However, when the first seal gas pipe 12 and the second seal gas pipe 16 are connected to the gas supply device via separate connecting pipes, the seal gas is generated between the first seal gas pipe 12 and the second seal gas pipe 16. The flow rate and type of can be changed.

  Note that the gas supply apparatus described above supplies the source gas to the source gas pipe 11, supplies the combustible gas to the combustible gas pipe 15, and the first auxiliary gas pipe 13 and the second auxiliary gas pipe 14. An auxiliary combustible gas is supplied to the first seal gas pipe 12 and the second seal gas pipe 16. The gas supply device can individually change the supply amount and flow rate of the raw material gas, the combustible gas, the auxiliary combustible gas, and the seal gas.

  Next, the arrangement of the injection ports 11A to 16A that are the injection ports of the respective gas pipes will be described. When the respective injection ports 11A to 16A are viewed from the gas injection side, the respective injection ports 11A to 16A are arranged as follows.

  The injection port 12A of the first seal gas pipe 12 is arranged so as to surround the outer periphery of the injection port 11A of the source gas pipe 11 over the entire circumference. That is, the injection port 11 </ b> A of the source gas pipe 11 is disposed inside the injection port 12 </ b> A of the first seal gas pipe 12. The injection ports 13A of the plurality of first auxiliary combustible gas pipes 13 are arranged at predetermined intervals so as to surround the outer periphery of the injection port 12A of the first seal gas pipe 12. Therefore, each injection port 13 </ b> A of the plurality of first auxiliary combustible gas pipes 13 also surrounds the injection port 11 </ b> A of the source gas pipe 11. In addition, the injection ports 14A of the plurality of second auxiliary combustion gas pipes 14 are arranged at predetermined intervals outside the injection ports 13A of the plurality of first auxiliary combustion gas pipes 13.

  In the case of the present embodiment, a plurality of injection ports 13A are arranged at predetermined equal intervals on a circle having a diameter larger than the diameter of the injection port 12A with the same position as the center of the injection port 11A as the center. A plurality of injection ports 14A are arranged at predetermined intervals equal to each other on a circle larger than the circle.

  A combustible gas pipe 15 is disposed outside the injection ports 14A of the plurality of second auxiliary combustible gas pipes 14 so as to surround the injection ports 14A. That is, the injection port 11A of the raw material gas pipe 11, the injection port 12A of the first seal gas pipe 12, the injection ports 13A of the plurality of first auxiliary combustible gas pipes 13, the plurality of injection ports 11A arranged in the positional relationship as described above. Each injection port 14 </ b> A of the second auxiliary combustible gas pipe 14 is disposed inside the injection port 15 </ b> A of the combustible gas pipe 15. Further, the injection port 16A of the second seal gas pipe 16 is disposed outside the injection port 15A of the combustible gas pipe 15 so as to surround the outer periphery of the injection port 15A over the entire circumference.

  Further, in the present embodiment, from the inner side to the outer side of the multi-tube burner 1, the injection port 11A of the source gas pipe 11, the injection port 12A of the first seal gas pipe 12, the injection port 15A of the combustible gas pipe 15, The injection ports are arranged concentrically in the order of the injection port 16A of the two-seal gas pipe 16.

  Further, the area of the injection region AR4 of the combustible gas is made larger than the area of the injection region AR1 of the raw material gas at the injection port 11A of the raw material gas pipe 11. Further, the area of the injection region AR4 of the combustible gas is larger than the area of the injection region AR2 of the seal gas that combines the injection port 12A of the first seal gas pipe 12 and the injection port 16A of the second seal gas pipe 16. Has been. In addition, compared to the area of the injection region AR3 of the auxiliary combustion gas, which includes the injection ports 13A of the plurality of first auxiliary combustion gas pipes 13 and the injection ports 14A of the plurality of second auxiliary combustion gas pipes 14, The area of the combustible gas injection area AR4 is increased. These injection regions AR1 to AR4 are regions where gas is injected. The combustible gas injection region AR4 includes the outer periphery of each injection port 13A of the first auxiliary combustible gas tube 13 and the second auxiliary combustible gas tube. The outer periphery of each of the 14 injection ports 14A and the outer periphery of the injection port 12A of the first seal gas pipe 12 are surrounded over the entire periphery.

  Next, gas combustion and soot generation by the multi-tube burner 1 will be described. The combustible gas injected from the injection port 15 </ b> A of the combustible gas pipe 15 burns together with the auxiliary combustible gas injected from the injection port 13 </ b> A of the first auxiliary combustible gas pipe 13. In this combustion flame, soot is generated by the combustion reaction of the raw material gas injected from the injection port 11A of the raw material gas pipe 11. Then, the generated soot is deposited on the target.

  At this time, the temperature of the soot deposited on the target is controlled by the auxiliary combustion gas injected from the injection port 14A of the second auxiliary combustion gas pipe 14. Specifically, the temperature of the auxiliary combustion gas injected from the injection port 14A of the second auxiliary combustion gas pipe 14 is combusted with the combustible gas, so that the temperature can be increased. Further, the raw material gas can be prevented from diffusing outside by the seal gas injected from the injection port 12A of the first seal gas pipe 12, and the raw material gas and the flammable gas can be reduced depending on the flow rate of the seal gas. The reaction position can be adjusted. Furthermore, it is possible to suppress the flame from spreading due to the seal gas injected from the injection port 16A of the second seal gas pipe 16, and to further prevent the combustible gas from touching the gas around the seal gas. it can.

  As described above, in the multi-tube burner 1 according to the present embodiment, the injection port 11A of the source gas pipe 11 and the injection port 13A of the first auxiliary combustible gas pipe 13 are arranged inside the injection port 15A of the combustible gas pipe 15. Has been. Further, the injection port 13A of the first auxiliary combustible gas pipe 13 is disposed so as to surround the injection port 11A of the raw material gas pipe 11 via the injection port 12A of the first seal gas pipe 12.

  According to such a multi-tube burner 1, the raw material gas is injected inside the auxiliary combustion gas, and the inflammable gas is injected so as to surround the auxiliary combustion gas and the raw material gas. Therefore, the auxiliary gas acts like a wall that suppresses the diffusion of the raw material gas, so that the raw material gas can be easily confined inside the auxiliary gas. Accordingly, it is possible to reduce the outward diffusion of the soot. Accordingly, it is possible to suppress a decrease in the amount of soot deposited on the target due to the diffusion of soot.

  In addition, since the injection port 13A of the first auxiliary combustible gas pipe 13 and the injection port 11A of the source gas pipe 11 are separately arranged, the gas flow rate can be set individually. Therefore, the flow rate of the auxiliary combustible gas injected from the injection port 13A of the first auxiliary combustible gas pipe 13 is set so that the soot does not diffuse to the outside due to the enlarged flame even if the flame becomes larger due to the increase in the amount of raw material gas. Can be adjusted. Accordingly, the flow rate of the combustible gas does not need to be increased so much that the soot temperature is lowered by the gas flow, so that it is difficult for the soot to adhere to the target. As a result, it is possible to suppress a decrease in the amount of soot deposited on the target. Note that since the flow rates of the source gas and the combustible gas can be individually adjusted, the optimum deposition efficiency can be adjusted according to the increase or decrease in the amount of the source gas.

  Thus, according to the multi-tube burner 1 according to the present embodiment, it is possible to increase the amount of soot deposition per unit raw material gas. Thus, soot can be deposited efficiently.

  Moreover, the multiple tube burner 1 of this embodiment is further provided with the 2nd auxiliary | assistant combustion gas pipe | tube 14 which flows auxiliary combustion gas. The injection port 14 </ b> A of the second auxiliary combustible gas pipe 14 is disposed on the inner side of the injection port 15 </ b> A of the combustible gas pipe 15, and is disposed on the outer side of the injection port 13 </ b> A of the first auxiliary combustible gas pipe 13. For this reason, combustible gas can be burned more efficiently and the temperature of the soot deposited on the target can be controlled. Moreover, since the auxiliary combustion gas doubles the raw material gas, the raw material gas can be more easily confined inside the auxiliary combustion gas.

  Furthermore, the multi-tube burner 1 of the present embodiment further includes a first seal gas pipe 12 through which a seal gas flows, and an injection port 11A of the source gas pipe 11 is disposed inside the injection port 12A of the first seal gas pipe 12. Has been. For this reason, it is possible to suppress the diffusion of the raw material gas to the outside, and it is possible to adjust the reaction position between the raw material gas injected from the injection ports 11A and 15A and the combustible gas by the flow rate of the seal gas. . Therefore, it is possible to further reduce the soot from diffusing outward, and it is possible to deposit the soot on an appropriate range of the target.

  Further, in the multi-tube burner 1 of the present embodiment, the injection port 16A of the second seal gas pipe 16 is disposed so as to surround the outer periphery of the injection port 15A of the combustible gas pipe 15. Therefore, it is possible to suppress the flame from spreading greatly, and soot can be deposited in a more appropriate range of the target.

(Second Embodiment)
Next, a multi-tube burner according to a second embodiment of the present invention will be described with reference to FIG. In addition, about the component which is the same as that of 1st Embodiment, or an equivalent component, the overlapping description is abbreviate | omitted except the case where it attaches | subjects the same referential mark and demonstrates especially.

  FIG. 2 is a view showing a state in which the injection port of the multi-tube burner according to the present embodiment is viewed from the gas injection side. As shown in FIG. 2, the multi-tube burner 2 according to the second embodiment includes a raw material gas pipe 11, a first seal gas pipe 12, a first combustible gas pipe 23, and a first auxiliary combustible gas pipe 24. A plurality of second auxiliary combustible gas pipes 14, a second combustible gas pipe 25, and a second seal gas pipe 16 are provided. That is, in this embodiment, it replaces with the some 1st auxiliary combustion gas pipe 13 of 1st Embodiment, and the 1st auxiliary combustion gas pipe 24 is provided. Moreover, in this embodiment, it replaces with the combustible gas pipe | tube 15 of 1st Embodiment, and the 1st combustible gas pipe | tube 23 arrange | positioned inside the 1st auxiliary | assistant combustible gas pipe 24 and the 1st arrange | positioned outside. Two combustible gas pipes 25 are provided. In FIG. 2, for easy visual recognition, the raw material gas pipe 11, the first seal gas pipe 12, the first combustible gas pipe 23, the first auxiliary combustible gas pipe 24, the second auxiliary combustible gas pipe 14, the first 2 Although the flammable gas pipe 25 and the second seal gas pipe 16 are indicated by hatching, the hatching does not indicate a cross section of the pipe.

  The first combustible gas pipe 23 is a pipe through which a combustible gas flows like the combustible gas pipe 15 of the first embodiment, and the first combustible gas pipe 23 has an end opposite to the injection end side. A gas supply device is connected via the connecting pipe. As combustible gas, the gas similar to the combustible gas of 1st Embodiment can be mentioned.

  The first auxiliary combustible gas pipe 24 is a pipe through which auxiliary combustible gas flows in the same manner as the first auxiliary combustible gas pipe 13 of the first embodiment. The end of the first auxiliary combustible gas pipe 24 opposite to the injection end side is connected to a gas supply device via a connecting pipe. Examples of the auxiliary combustion gas include the same gases as the auxiliary combustion gas of the first embodiment.

  The 2nd combustible gas pipe 25 is a pipe | tube which flows the combustible gas made into the structure similar to the combustible gas pipe 15 of 1st Embodiment. As combustible gas, the gas similar to the combustible gas of 1st Embodiment can be mentioned.

  Next, the arrangement of the injection port of each gas pipe will be described. However, the description of the injection port arrangement similar to that of the first embodiment is omitted. The injection port 11 </ b> A of the source gas pipe 11 and the injection port 12 </ b> A of the first seal gas pipe 12 surrounding the raw gas pipe 11 are disposed inside the injection port 23 </ b> A of the first combustible gas pipe 23. Accordingly, the injection port 23A of the first combustible gas pipe 23 surrounds the outer periphery of the injection port 12A of the first seal gas pipe 12 over the entire circumference, and the raw material gas pipe is connected via the injection port 12A of the first seal gas pipe 12. 11 injection ports 11A are surrounded all around.

  Further, the injection port 23 </ b> A of the first combustible gas pipe 23 is disposed inside the injection port 24 </ b> A of the first auxiliary combustible gas pipe 24. Therefore, the injection port 24A of the first auxiliary combustible gas pipe 24 surrounds the entire outer periphery of the injection port 23A of the first combustible gas pipe 23, and the injection port 23A of the first combustible gas pipe 23 and the first seal gas. The injection port 11A of the source gas pipe 11 is surrounded over the entire circumference via the injection port 12A of the pipe 12. Further, outside the injection port 13A of the first auxiliary combustible gas pipe 13, the injection ports 14A of the plurality of second auxiliary gas pipes 14 are arranged at predetermined intervals.

  Further, the injection port 25A of the second combustible gas pipe 25 is arranged so as to surround the outer periphery of the injection port 24A of the first auxiliary combustible gas pipe 24 over the entire circumference. That is, the injection port 11A of the raw material gas pipe 11, the injection port 12A of the first seal gas pipe 12, the injection port 23A of the first combustible gas pipe 23, and the first auxiliary combustible gas pipe arranged in the above positional relationship. The 24 injection ports 24 </ b> A and the injection ports 14 </ b> A of the plurality of second auxiliary combustible gas pipes 14 are arranged inside the injection ports 15 </ b> A of the second combustible gas pipes 25. Therefore, a plurality of second auxiliary combustible gas pipes 14 are arranged between the inner wall of the injection port 25A of the second combustible gas pipe 25 and the outer wall of the injection port 24A of the first auxiliary combustible gas pipe 24.

  In such a multi-tube burner 2, the injection region AR4 of the injection port 23A of the first combustible gas pipe 23 surrounds the outer periphery of the injection port 12A of the first seal gas pipe 12 over the entire circumference. In addition, the injection region AR3 of the injection port 24A of the first auxiliary combustible gas pipe 24 surrounds the outer periphery of the injection port 23A of the first combustible gas pipe 23 over the entire circumference. Therefore, the injection region AR3 of the injection port 24A of the first auxiliary combustible gas pipe 24 surrounds the outer periphery of the injection port 11A of the source gas pipe 11 over the entire circumference via the injection port 23A of the first combustible gas pipe 23. Yes. Further, the injection region AR4 of the injection port 25A of the second combustible gas pipe 25 includes the outer periphery of each injection port 14A of the second auxiliary combustible gas pipe 14, and the outer periphery of the injection port 24A of the first auxiliary combustible gas pipe 24. Is surrounded all around.

  Thus, according to the multi-tube burner 2 of the present embodiment, the injection port 24A of the first auxiliary combustible gas pipe 24 surrounds the outside of the injection port 11A of the raw material gas pipe 11 over the entire circumference. For this reason, compared with the case where each injection port 13A of the plurality of first auxiliary combustion gas pipes 13 is arranged around the injection port 11A of the raw material gas pipe 11 at a predetermined interval as in the first embodiment, the auxiliary combustion gas Therefore, the diffusion of the raw material gas can be further suppressed, and the combustion can be made uniform in the circumferential direction, so that the soot generation can be made uniform in the circumferential direction.

  As mentioned above, although this invention was demonstrated to the example for embodiment, this invention is not limited to these.

  For example, when the injection ports 11A to 16A of the first embodiment are viewed from the gas injection side, the injection ports 11A to 16A are on the same surface as long as the positional relationship described above in the first embodiment is satisfied. It does not need to be arranged even if it is arranged. Similarly, when the injection ports 11A, 12A, 23A, 24A, 14A, 25A, and 16A of the second embodiment are viewed from the gas injection side, the injection ports have the positional relationship described above in the second embodiment. As long as they are arranged, they may or may not be arranged on the same surface. Moreover, although each said injection port was made circular, it may be non-circular.

  Moreover, in the said embodiment, the 2nd auxiliary combustion gas pipe 14, the 1st seal gas pipe 12, and the 2nd seal gas pipe 16 were provided. However, all of the second auxiliary combustion gas pipe 14, the first sealing gas pipe 12, and the second sealing gas pipe 16 may be omitted, and the second auxiliary combustion gas pipe 14, the first sealing gas pipe 12, and the first sealing gas pipe 12 may be omitted. One or two of the two seal gas pipes 16 may be omitted.

  Hereinafter, the content of the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

Example 1
Soot was deposited on the target by the OVD method using the multi-tube burner 1 in the first embodiment. At this time, the deposition efficiency of soot was measured when the flow rate of the raw material gas flowing through the raw material gas tube 11 and the flow rate of the auxiliary combustion gas flowing through the first auxiliary combustion gas tube 13 were changed. The deposition efficiency is calculated from the weight of the soot deposited on the target during the experiment, assuming that all Si atoms contained in the raw material are SiO ₂ and adhere to the target as 1.0 (100%). .

  The diameter of the injection port 11A of the raw material gas pipe 11 was 3.6 mm, and the diameter of the injection port 13A of the first auxiliary combustible gas pipe 13 was 1.6 mm. In addition, octamethylcyclotetrasiloxane was used as a raw material for the raw material gas, hydrogen was used as the combustible gas, oxygen was used as the auxiliary combustible gas, and nitrogen was used as the seal gas. The flow rate of the raw material gas was changed from 20 m / s to 35 m / s, and the flow rate of the auxiliary combustible gas was changed from 10 m / s to 20 m / s.

  The flow rate of the raw material gas was changed to a predetermined ratio with the flow rate of the auxiliary combustion gas. The flow rate of the combustible gas was fixed at 0.15 m / s. Furthermore, the diameter of the injection port 14A of the second auxiliary combustion gas pipe 14 is the same as the injection port 13A of the first auxiliary combustion gas pipe 13, and the flow rate of the auxiliary combustion gas flowing through the second auxiliary combustion gas pipe 14 is the first auxiliary combustion property. The flow velocity is the same as that flowing through the gas pipe 13. Furthermore, the flow rate of the seal gas was fixed at 0.3 m / s.

  FIG. 3 is a graph showing the relationship between gas flow velocity and deposition efficiency in Example 1. As shown in FIG. 3, when the ratio of the flow rate of the auxiliary combustible gas to the flow rate of the raw material gas (flow rate ratio) is within the range of 0.35 to 0.75, the deposition efficiency is 0.5 or more. Moreover, when the flow rate ratio was within the range of 0.4 to 0.75, the deposition efficiency was 0.7 or more.

  Thus, if the flow rate ratio is in the range of 0.35 to 0.75, even if the flow rate of the source gas changes within the range of 20 g / min to 38 g / min, the deposition efficiency of 50% or more is secured. I can confirm that I can do it. Moreover, if the flow rate ratio is in the range of 0.4 to 0.75, even if the flow rate of the source gas changes within the range of 20 g / min to 38 g / min, it is possible to ensure a deposition efficiency of 70% or more. I was able to confirm.

(Example 2)
The diameter of the injection port of the raw material gas pipe is 2.8 mm, and the other conditions are the same as in Example 1 except that the flow rate of the raw material gas flowing through the raw material gas pipe and the flow rate of the auxiliary combustion gas flowing through the first auxiliary combustion gas pipe are changed. The deposition efficiency of soot was measured.

  FIG. 4 is a graph showing the relationship between gas flow velocity and deposition efficiency in Example 2. As shown in FIG. 4, when the ratio of the flow rate of the auxiliary combustible gas to the flow rate of the raw material gas is within the range of 0.35 to 0.75, the deposition efficiency is 0. It became 5 or more. In addition, when the flow rate ratio was in the range of 0.4 to 0.75, the deposition efficiency was 0.7 or more, as in Example 1.

  Thus, it was confirmed that the deposition efficiency can be ensured as in Example 1 even when the diameter of the injection port of the source gas pipe is small. In addition, it is considered that the ratio of the flow rate of the source gas and the flow rate of the first auxiliary combustion gas mainly contributes to the deposition efficiency. For example, when the seal gas is not used, the range in which the source gas diffuses and soot accumulates tends to be wider than when the seal gas is used, but the effect on the deposition efficiency is an auxiliary combustion for the flow rate of the source gas. This is considered to be small compared with the influence of the ratio of the flow rate of the sex gas.

  As described above, according to the present invention, a multi-tube burner capable of efficiently depositing soot is provided, and can be used in industries for manufacturing optical fibers.

1, 2 ... Multiple pipe burner 11 ... Raw material gas pipe 12 ... First seal gas pipe 13, 24 ... First auxiliary gas pipe 14 ... Second auxiliary gas pipe 15 ... Combustible gas pipe 16 ... second seal gas pipe 23 ... first combustible gas pipe 25 ... second combustible gas pipe 11A ... injection port 12A of raw material gas pipe ... first Injection port 13A, 24A of the seal gas pipe ... Injection port 14A of the first auxiliary gas pipe ... Injection port 15A of the second auxiliary gas pipe ... Injection port 16A of the combustible gas pipe ... No. 2 seal gas pipe injection port 23A ... first combustible gas pipe injection port 25A ... second combustible gas pipe injection port

By the way, when the amount of source gas increases, the flame spreads when the combustion reaction occurs, and soot tends to diffuse due to the flame. In the burner of the above-mentioned patent document 1, the 1st field which injects the mixed gas of source gas and auxiliary combustion gas is provided in the innermost peripheral side of the injection mouth of a burner. For this reason, there is a concern that soot spreads to the outer peripheral side of the first region due to the flame that spreads widely, and the amount of soot deposited on the target decreases.

On the other hand, if the flow rate of the nitrogen gas injected from the second region is increased, it is considered that soot can be prevented from diffusing outside the first region. However, when the flow rate of nitrogen gas is increased, the soot temperature is lowered by the gas flow, and there is a concern that the amount of soot deposited may be reduced without the soot adhering to the target.

Claims (7)

A source gas pipe through which source gas flows,
A combustible gas pipe for flowing a combustible gas;
A first auxiliary gas pipe for flowing auxiliary gas,
With
The injection port of the source gas pipe and the injection port of the first auxiliary combustible gas pipe are disposed inside the injection port of the combustible gas pipe,
The multi-tube burner, wherein an injection port of the first auxiliary combustible gas pipe is disposed so as to surround the injection port of the raw material gas pipe. A second auxiliary gas pipe for flowing the auxiliary gas;
The injection port of the second auxiliary combustible gas pipe is disposed outside the injection port of the first auxiliary combustible gas pipe inside the injection port of the combustible gas pipe. Multi-tube burner. A first seal gas pipe for flowing a seal gas;
The injection port of the source gas pipe is disposed inside the injection port of the first seal gas pipe,
3. The multi-tube burner according to claim 1, wherein an injection port of the first auxiliary combustible gas pipe is disposed so as to surround the injection port of the first seal gas pipe. The ratio between the flow rate of the raw material gas flowing through the raw material gas tube and the flow rate of the auxiliary combustion gas flowing through the first auxiliary combustion gas tube is in a range of 0.35 to 0.75. Item 4. The multiple tube burner according to any one of Items 1 to 3. The multi-tube burner according to claim 4, wherein the ratio is in a range of 0.4 to 0.75. 6. The multi-tube burner according to claim 1, wherein an injection port of the source gas pipe is disposed inside an injection port of the first auxiliary combustible gas pipe. A plurality of the first auxiliary combustible gas pipes;
6. The injection port of each of the plurality of first auxiliary combustible gas pipes is arranged at predetermined intervals around the injection port of the source gas pipe. Multi-tube burner.

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