CN106746587B - Burner for manufacturing optical fiber preform - Google Patents
Burner for manufacturing optical fiber preform Download PDFInfo
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- CN106746587B CN106746587B CN201611219517.5A CN201611219517A CN106746587B CN 106746587 B CN106746587 B CN 106746587B CN 201611219517 A CN201611219517 A CN 201611219517A CN 106746587 B CN106746587 B CN 106746587B
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- combustion
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- gas outlet
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/04—Multi-nested ports
- C03B2207/14—Tapered or flared nozzles or ports angled to central burner axis
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/36—Fuel or oxidant details, e.g. flow rate, flow rate ratio, fuel additives
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- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Gas Burners (AREA)
- Pre-Mixing And Non-Premixing Gas Burner (AREA)
Abstract
The application discloses a burner for manufacturing an optical fiber preform, which comprises a gas injection end, wherein the gas injection end sequentially comprises a central nozzle, an isolation gas outlet externally embedded on the central nozzle, a plurality of inner layer combustion-supporting gas outlets circumferentially uniformly distributed around the isolation gas outlet, a plurality of composite gas outlets circumferentially uniformly distributed around the isolation gas outlet, and an annular outer layer combustion-supporting gas outlet, and the composite gas outlets comprise mutually nested combustible gas outlets and middle combustion-supporting gas outlets. The circular outer layer combustion-supporting gas outlet at the outermost side of the application enhances the mixing of the raw material gas and the combustion-supporting gas above the burner; the combustion-supporting gas outlets of the inner layer, the middle layer and the outer layer are matched with the central nozzle in the middle and the combustible gas outlet in the middle layer, so that the gas mixing degree is effectively increased.
Description
Technical Field
The application relates to the field of optical fiber preform manufacturing, in particular to a burner for manufacturing an optical fiber preform.
Background
The processes for manufacturing the optical fiber preform mainly include VAD, OVD, MCVD, PCVD, etc., VAD and OVD are external deposition methods, and MCVD and PCVD are in-tube deposition methods. The radial dimension of the optical fiber preform manufactured by the in-tube deposition method is limited, the rule outside the tube is not limited, and the method can be used for manufacturing a preform with larger radial dimension, which has certain advantages in the manufacturing cost. In VAD and OVD processes, raw material silicon tetrachloride (SiCl 4 ) Vaporized gas passage and oxygen (O) 2 ) Is sprayed to a rotating target rod together with hydrogen (or methane) and oxygen flame, and under the action of heat energy, raw materials undergo hydrolysis reaction to generate silicon dioxide (SiO) 2 ) Dust particles generated by pyrolysis of silicon dioxide particles are adsorbed layer by layer on crossing flameAnd (3) forming a porous preform blank on the rotating target rod, introducing a drying agent (such as chlorine) to remove impurities such as water and metal under the condition that the temperature of the generated porous preform blank ranges from 1100 ℃ to 1550 ℃, sintering the porous preform blank into a glass preform, and drawing the glass preform into an optical fiber.
In the vapor deposition process, a temperature gradient formed by a difference between the flame temperature and the deposition surface (surface of the build-up rod) temperature pushes fine particles toward the surface of the build-up rod and adsorbs on the surface of the rod. Dust particles produced by high temperature oxidation and hydrolysis gradually polymerize into larger sized polymer particles and undergo preliminary dehydration during transport, diffusion, and thermomigration through the target rod. In the region near the burner port, the number density of the reaction-produced dust particles increases rapidly and forms particle-collecting nuclei rapidly, and then passes through the rapid-collecting zone, so that the number density of the dust particles decreases rapidly. As the particle number density decreases, the particle collision rate decreases, resulting in a slower rate of polymerization of the particles, and also a slower rate of decrease in the particle number density. Temperature is a critical factor in particle formation, and the size of the primary particles depends on the solid state diffusion coefficient at that temperature. Increasing the flame temperature can thus increase the particle size of the primary particles, with the flame temperature affecting to a large extent the degree of bonding between the particles. At high temperatures, the more intense the thermal movement of the particles, the higher the probability of mutual collisions and binding between the particles, and the correspondingly greater the probability of binding into larger particles, resulting in the formation of large particles. At low temperatures, the binding is much slower than the collision between particles, resulting in the formation of irregular particles with a large specific surface area (surface area to volume ratio). Therefore, the higher the heat value of the burner, the more fully reacted, and the higher the dust deposition efficiency, with substantially the same amount of gas flow.
As shown in fig. 1 and 2, the structure of the existing silicon tetrachloride burner is that a central nozzle 1 of the silicon tetrachloride burner sprays raw material silicon tetrachloride evaporation gas, combustion-supporting gas is sprayed from small hole gas nozzles 2 and 4 uniformly distributed on the outer side of the central nozzle 1, combustible gas hydrogen is sprayed from a middle nozzle 3, a mixed hydrolysis combustion reaction is carried out above a lamp socket, and silicon dioxide dust is produced and deposited on a target rod. Silicon tetrachloride is used as a reaction raw material gas, and chlorine and hydrogen chloride with strong corrosiveness and toxicity are generated in the production process, so that the purification treatment cost is high, and once the treatment is incomplete (such as the fault of treatment equipment), waste gas can enter the environment to cause pollution.
The deposition process using octamethyl cyclotetrasiloxane as raw material has no toxic and harmless silicon dioxide, water, carbon dioxide and other reaction products, and has no adverse effect on environment. As shown in fig. 3 and 4, in the conventional octamethyl cyclotetrasiloxane burner, octamethyl cyclotetrasiloxane mixed combustion-supporting gas oxygen is sprayed from a central nozzle 5, isolation gas is sprayed from an isolation nozzle 6 sleeved outside the central nozzle, combustion-supporting gas oxygen is sprayed from oxygen nozzles 8 and 9, combustible gas hydrogen is sprayed from a hydrogen nozzle 7, and after being sprayed in a certain shape, mixing and combustion reaction occur to generate silica dust. However, this structure has problems such as insufficient reaction, easy blockage of the burner ports, low adhesion rate of silica dust generated, and the like, because the raw material gas is insufficiently mixed and the flame is emitted, resulting in insufficient combustion heat.
Disclosure of Invention
The present application addresses at least one of the above-mentioned problems by providing a burner for manufacturing an optical fiber preform. The problems of insufficient mixing, flame divergence and insufficient combustion heat of the existing burner are solved.
The technical scheme adopted by the application is as follows:
the utility model provides a make combustor of optical fiber perform, includes the gas injection end, the gas injection end is from interior to exterior including central spout in proper order, the isolation gas export of inlaying on central spout outward, around the export of isolation gas a plurality of inlayer combustion-supporting gas export of circumference equipartition, around the export of isolation gas a plurality of compound gas outlets of circumference equipartition and the export of annular outer combustion-supporting gas of annular, compound gas outlet includes the combustible gas export of mutual nestification and middle combustion-supporting gas export.
The outer annular combustion-supporting gas outlet at the outermost side enhances the mixing of the raw material gas and the combustion-supporting gas above the burner; the combustion-supporting gas outlets of the inner layer, the middle layer and the outer layer are matched with the central nozzle in the middle and the combustible gas outlet in the middle layer, so that the gas mixing degree can be improved, the gas can be fully combusted, the flame heat value is higher and stable, the combustible gas premixing form is more favorable for generating the reaction of easily-adsorbed agglomerated particles, and the crystallization and blockage of the raw material gas at the port can be prevented.
The burner takes the octamethyl cyclotetrasiloxane as the raw material, because the silicon element content of the octamethyl cyclotetrasiloxane accounts for about 80 percent of the total amount, compared with the silicon tetrachloride raw material, the burner has the advantages that silicon dioxide dust is generated in unit time, no toxic hydrogen chloride gas is generated in byproducts of the reaction, the burner has high cleanliness, no pollution to the environment, the deposition efficiency is improved, and the investment and the cost of waste gas treatment are greatly reduced.
Optionally, the combustible gas outlet is externally embedded on the middle combustion-supporting gas outlet, and the combustible gas outlet is arranged inside the gas injection end and is spaced from the middle combustion-supporting gas outlet.
The interval refers to that the combustible gas outlet and the middle combustion-supporting gas outlet are not on the same plane, and a plurality of distances are arranged between the combustible gas outlet and the middle combustion-supporting gas outlet. The combustible gas outlet and the intermediate combustion gas outlet are designed so that the combustible gas and the combustion gas are sufficiently mixed.
Optionally, the central nozzle, the isolation gas outlet, the inner layer combustion-supporting gas outlet, the middle combustion-supporting gas outlet and the outer layer combustion-supporting gas outlet are all positioned on the same plane.
Optionally, the burner further includes a central channel, an isolation gas channel, an inner layer combustion-supporting gas channel, a combustible gas channel, an intermediate combustion-supporting gas channel and an outer layer combustion-supporting gas channel, wherein an outlet of the central channel is a central nozzle, an outlet of the isolation gas channel is an isolation gas outlet, an outlet of the inner layer combustion-supporting gas channel is an inner layer combustion-supporting gas outlet, an outlet of the combustible gas channel is a combustible gas outlet, an outlet of the intermediate combustion-supporting gas channel is an intermediate combustion-supporting gas outlet, and an outlet of the outer layer combustion-supporting gas channel is an outer layer combustion-supporting gas outlet;
the inner layer combustion-supporting gas channel is provided with a first buffer chamber adjacent to the inner layer combustion-supporting gas outlet, the combustible gas channel is provided with a second buffer chamber adjacent to the combustible gas outlet, the middle combustion-supporting gas channel is provided with a third buffer chamber adjacent to the middle combustion-supporting gas outlet, and the outer layer combustion-supporting gas channel is provided with a fourth buffer chamber adjacent to the outer layer combustion-supporting gas outlet.
The design of the buffer chamber ensures that the gas conveyed to the burner is subjected to expansion and compression processes, so that the flow velocity distribution at the outlet is more uniform, and the burner is more stable in combustion.
Optionally, the outer layer combustion-supporting gas channel comprises a conical portion at the end, and the outer layer combustion-supporting gas outlet is a small diameter end of the conical portion.
Optionally, the angle between the gas spraying direction of the conical part and the axis of the central nozzle is 0.5-5 degrees, and the gas sprayed from the outer layer combustion-supporting gas outlet is focused at a position 150-250mm away from the end face of the burner.
The outer layer combustion-supporting gas outlet determines a flame burning torch, has a great influence on flame temperature, and the structure of the conical part limits a focusing position, so that the flame temperature can reach an optimal value, the temperature of burning flame and the agglomeration degree of generated dust particles are fully improved, and the adsorption rate of the dust particles on the optical fiber preform target rod is increased.
Optionally, the ratio of the sum of the cross-sectional areas of the combustion-supporting gas outlets of each inner layer to the cross-sectional area of the first buffer chamber is less than or equal to 0.2, the ratio of the sum of the cross-sectional areas of the combustible gas outlets to the cross-sectional area of the second buffer chamber is less than or equal to 0.2, and the ratio of the sum of the cross-sectional areas of the intermediate combustion-supporting gas outlets to the cross-sectional area of the third buffer chamber is less than or equal to 0.2; the fourth buffer chamber is of an outward protruding streamline shape, and the ratio of the maximum cross-sectional area of the fourth buffer chamber to the cross-sectional area of the combustion-supporting gas outlet of the outer layer is 8-20; the length range of each buffer chamber is more than or equal to 50mm.
Optionally, the burner comprises a central tube, an insulating gas tube, a first vent, a second vent, and an outer tube;
the inner space of the central tube is a central channel, the isolating gas tube is sleeved on the central tube, and a gap between the isolating gas tube and the central tube is an isolating gas channel;
the first ventilation piece comprises a first pipe body, a cylindrical cavity is formed in the side wall of the first pipe body, the cavity is a second buffer chamber, one end of the first pipe body is provided with a plurality of second combustion-supporting pipes which are uniformly distributed around the axis direction of the first pipe body, the second combustion-supporting pipes are communicated with the second buffer chamber, and the inner spaces of the second buffer chamber and the second combustion-supporting pipes are middle combustion-supporting gas channels;
the second ventilation piece comprises a second pipe body, a partition plate is arranged at the first end of the second pipe body, the second pipe body further comprises a partition pipe penetrating through the second end of the second pipe body and fixed with the partition plate, and the second pipe body and the partition pipe are coaxially arranged; the outer end face of the partition plate is also provided with a plurality of first combustion-supporting pipes uniformly distributed around the axis direction of the second pipe body and a plurality of gas pipes uniformly distributed around the axis direction of the second pipe body, the outer side port of the first combustion-supporting pipe is an inner layer combustion-supporting gas outlet, and the height of the gas pipes is smaller than that of the first combustion-supporting pipe; the partition plate is provided with a central hole for the central pipe and the isolation gas pipe to pass through, the isolation gas pipe is sleeved in the partition pipe, and one end of the isolation gas pipe passes through the central hole; the first pipe body is sleeved in the second pipe body and sleeved on the separation pipe, the second combustion-supporting pipe penetrates through the corresponding gas pipe, the height of the second combustion-supporting pipe positioned outside the partition plate is larger than that of the gas pipe, a gap between the inner side wall of the second pipe body and the outer side wall of the first pipe body is a third buffer chamber, the gas pipe is communicated with the third buffer chamber, and the gap between the gas pipe and the second combustion-supporting pipe and the third buffer chamber are combustible gas channels; the gap between the separation pipe and the isolation gas pipe is a first buffer chamber, the first combustion-supporting pipe is communicated with the first buffer chamber, and the inner spaces of the first buffer chamber and the first combustion-supporting pipe are inner-layer combustion-supporting gas channels;
the second ventilation piece is provided with a guide pipe at the outer side of the partition board, the guide pipe is of a conical structure, and the inner diameter of the guide pipe is smaller as the guide pipe is far away from the partition board;
the outer tube is sleeved on the second ventilation piece, the gap between the inner side wall of the outer tube and the outer side wall of the second ventilation piece is an outer layer combustion-supporting gas channel, the corresponding part of the outer tube and the guide tube is provided with a conical inner side wall, and a conical part of the outer layer combustion-supporting gas channel is arranged between the conical inner side wall and the outer side wall of the guide tube.
Optionally, the outer tube further includes a concave annular arc groove, and a space between the annular arc groove and the second tube body is the fourth buffer chamber.
Optionally, the burner further comprises:
the isolation gas inlet pipe is communicated with the isolation gas channel;
the first combustion-supporting gas inlet pipe is communicated with the first cache chamber;
the second combustion-supporting gas inlet pipe is communicated with the second cache chamber;
the fuel gas inlet pipe is communicated with the third cache chamber;
and the third combustion-supporting gas inlet pipe is communicated with the outer layer combustion-supporting gas channel.
The beneficial effects of the application are as follows: the outer annular combustion-supporting gas outlet at the outermost side enhances the mixing of the raw material gas and the combustion-supporting gas above the burner; the combustion-supporting gas outlets of the inner layer, the middle layer and the outer layer are matched with the central nozzle in the middle and the combustible gas outlet in the middle layer, so that the gas mixing degree can be improved, the gas can be fully combusted, the flame heat value is higher and stable, the combustible gas premixing form is more favorable for generating the reaction of easily-adsorbed agglomerated particles, and the crystallization and blockage of the raw material gas at the port can be prevented.
Description of the drawings:
FIG. 1 is a top view of a prior art silicon tetrachloride burner;
FIG. 2 is a cross-sectional view of a prior art silicon tetrachloride burner;
FIG. 3 is a top view of a prior art octamethyl cyclotetrasiloxane burner;
FIG. 4 is a cross-sectional view of a prior art octamethyl cyclotetrasiloxane burner;
FIG. 5 is a top view of a burner for fabricating an optical fiber preform according to the present application;
FIG. 6 is a cross-sectional view of a burner for fabricating an optical fiber preform according to the present application;
FIG. 7 is an exploded view of a burner for fabricating an optical fiber preform according to the present application;
FIG. 8 is a front view of the center tube;
FIG. 9 is a front view of an isolation gas duct;
FIG. 10 is a cross-sectional view of the second venting member;
FIG. 11 is a schematic structural view of a second venting member;
FIG. 12 is a cross-sectional view of a first vent;
FIG. 13 is a schematic view of the structure of the first vent;
FIG. 14 is a cross-sectional view of the outer tube;
FIG. 15 is a schematic structural view of an outer tube;
FIG. 16 is a graph comparing deposition efficiency curves of a burner of the present application with that of a prior art silicon tetrachloride burner in experimental verification;
FIG. 17 is a graph comparing deposition efficiency curves of the burner of the present application with that of a conventional octamethyl cyclotetrasiloxane burner in experimental verification.
The reference numerals in the drawings are as follows:
1. a central spout; 2. a small hole gas nozzle; 3. an intermediate layer nozzle; 4. a small hole gas nozzle; 5. a central orifice; 6. isolating the nozzle; 7. a hydrogen gas jet; 8. an oxygen nozzle; 9. an oxygen nozzle; 10. a central spout; 11. isolating the gas outlet; 12. an inner layer combustion-supporting gas outlet; 13. a combustible gas outlet; 14. an intermediate combustion-supporting gas outlet; 15. an outer layer combustion-supporting gas outlet; 16. a gas injection port; 17. a central tube; 18. an isolation gas tube; 19. a first vent; 20. a second vent; 21. an outer tube; 22. isolating the gas inlet pipe; 23. a second combustion-supporting gas inlet pipe; 24. a first combustion-supporting gas inlet pipe; 25. a fuel gas inlet pipe; 26. a third combustion-supporting gas inlet pipe; 27. a central passage; 28. isolating the gas channel; 29. a first buffer chamber; 30. a second buffer chamber; 31. a third buffer chamber; 32. a fourth buffer chamber; 33. a taper portion; 34. a second combustion-supporting pipe; 35. a gas pipe; 36. a first combustion-supporting pipe; 37. a guide tube; 38. a second tube body; 39. a partition pipe; 40. a partition plate; 41. a central bore; 42. a first tube body; 43. a tapered inner sidewall; 44. an annular arc-shaped groove; 45. and an outer layer combustion-supporting gas channel.
The specific embodiment is as follows:
the present application will be described in detail with reference to the accompanying drawings.
Example 1
As shown in fig. 5 and 6, a burner for manufacturing an optical fiber preform comprises a gas injection end 16, wherein the gas injection end 16 sequentially comprises a central nozzle 10, an isolation gas outlet 11 externally embedded on the central nozzle 10, a plurality of inner combustion-supporting gas outlets 12 circumferentially uniformly distributed around the isolation gas outlet 11, a plurality of composite gas outlets circumferentially uniformly distributed around the isolation gas outlet 11, and an annular outer combustion-supporting gas outlet 15 from inside to outside, and the composite gas outlets comprise mutually nested combustible gas outlets 13 and an intermediate combustion-supporting gas outlet 14.
As shown in fig. 5 and 6, in the present embodiment, the combustible gas outlet 13 is externally embedded on the intermediate combustion-supporting gas outlet 14, and the combustible gas outlet 13 is inside the gas injection end 16 with a space from the intermediate combustion-supporting gas outlet 14; the central nozzle 10, the isolation gas outlet 11, the inner combustion gas outlet 12, the middle combustion gas outlet 14 and the outer combustion gas outlet 15 are all positioned on the same plane. The interval in this embodiment means that the combustible gas outlet 13 and the intermediate combustion gas outlet 14 are not on the same plane, and there are several distances between them. The combustible gas outlet 13 and the intermediate combustion gas outlet 14 are designed so that the combustible gas and the combustion gas are sufficiently mixed.
As shown in fig. 6, in the present embodiment, the burner further includes a central channel 27, an isolation gas channel 28, an inner combustion-supporting gas channel, a combustible gas channel, an intermediate combustion-supporting gas channel, and an outer combustion-supporting gas channel 45, wherein the outlet of the central channel 27 is the central nozzle 10, the outlet of the isolation gas channel 28 is the isolation gas outlet 11, the outlet of the inner combustion-supporting gas channel is the inner combustion-supporting gas outlet 12, the outlet of the combustible gas channel is the combustible gas outlet 13, the outlet of the intermediate combustion-supporting gas channel is the intermediate combustion-supporting gas outlet 14, and the outlet of the outer combustion-supporting gas channel 45 is the outer combustion-supporting gas outlet 15;
the inner combustion gas channel has a first buffer chamber 29 adjacent to the inner combustion gas outlet 12, the combustible gas channel has a second buffer chamber 30 adjacent to the combustible gas outlet 13, the intermediate combustion gas channel has a third buffer chamber 31 adjacent to the intermediate combustion gas outlet 14, and the outer combustion gas channel 45 has a fourth buffer chamber 32 adjacent to the outer combustion gas outlet 15.
The design of the buffer chamber ensures that the gas conveyed to the burner is subjected to expansion and compression processes, so that the flow velocity distribution at the outlet is more uniform, and the burner is more stable in combustion.
In the present embodiment, as shown in fig. 6, the outer combustion-supporting gas passage 45 includes a tapered portion 33 at an end, and the outer combustion-supporting gas outlet 15 is a small diameter end of the tapered portion 33. The angle between the gas spraying direction of the conical part 33 and the axis of the central nozzle 10 is 0.5-5 degrees, and the gas sprayed from the outer layer combustion-supporting gas outlet 15 is focused at a position 150-250mm away from the end face of the burner. The outer combustion-supporting gas outlet 15 determines a flame focusing torch, has a great influence on flame temperature, and the conical part 33 is structured and defines a focusing position, so that the flame temperature can reach an optimal value, the temperature of the combustion flame and the agglomeration degree of generated dust particles are fully improved, and the adsorption rate of the dust particles on the optical fiber preform target rod is increased.
In the present embodiment, the ratio of the sum of the cross-sectional areas of the combustion-supporting gas outlets 12 of each inner layer to the cross-sectional area of the first buffer chamber 29 is equal to or less than 0.2, the ratio of the sum of the cross-sectional areas of the combustible gas outlets 13 to the cross-sectional area of the second buffer chamber 30 is equal to or less than 0.2, and the ratio of the sum of the cross-sectional areas of the intermediate combustion-supporting gas outlets 14 to the cross-sectional area of the third buffer chamber 31 is equal to or less than 0.2; the fourth buffer chamber 32 is an outward-protruding streamline shape, and the ratio of the maximum cross-sectional area of the fourth buffer chamber to the cross-sectional area of the outer layer combustion-supporting gas outlet 15 ranges from 8 to 20; the length range of each buffer chamber is more than or equal to 50mm.
As shown in fig. 7 to 15, in the present embodiment, the burner includes a central tube 17, an insulating gas tube 18, a first ventilation member 19, a second ventilation member 20, and an outer tube 21;
the inner space of the central tube 17 is a central channel 27, the isolating gas tube 18 is sleeved on the central tube 17, and the gap between the isolating gas tube 18 and the central tube 17 is an isolating gas channel 28;
as shown in fig. 6, 12 and 13, the first ventilation member 19 includes a first pipe body 42, a cylindrical cavity is formed in a side wall of the first pipe body 42, the cavity is a second buffer chamber 30, one end of the first pipe body 42 is provided with a plurality of second combustion supporting pipes 34 uniformly distributed around an axis direction of the first pipe body 42, the second combustion supporting pipes 34 are communicated with the second buffer chamber 30, and an inner space of the second buffer chamber 30 and an inner space of the second combustion supporting pipes 34 are intermediate combustion supporting gas channels;
as shown in fig. 6, 10 and 11, the second venting member 20 includes a second tube body 38, a first end of the second tube body 38 has a partition plate 40, the second tube body 38 further includes a partition tube 39 passing through a second end of the second tube body 38 and fixed to the partition plate 40, and the second tube body 38 is disposed coaxially with the partition tube 39; the outer end face of the partition plate 40 is also provided with a plurality of first combustion-supporting pipes 36 which are uniformly distributed around the axial direction of the second pipe body 38 and a plurality of gas pipes 35 which are uniformly distributed around the axial direction of the second pipe body 38, the outer side port of the first combustion-supporting pipe 36 is the inner layer combustion-supporting gas outlet 12, and the height of the gas pipes 35 is smaller than that of the first combustion-supporting pipe 36; the partition plate 40 has a center hole 41 through which the center tube 17 and the insulating gas tube 18 pass, the insulating gas tube 18 is sleeved in the partition tube 39, and one end passes through the center hole 41; the first pipe body 42 is sleeved in the second pipe body 38 and sleeved on the separation pipe 39, the second combustion-supporting pipe 34 passes through the corresponding gas pipe 35, the height of the second combustion-supporting pipe 34 positioned outside the partition plate 40 is larger than that of the gas pipe 35, a gap between the inner side wall of the second pipe body 38 and the outer side wall of the first pipe body 42 is a third buffer chamber 31, the gas pipe 35 is communicated with the third buffer chamber 31, and a gap between the gas pipe 35 and the second combustion-supporting pipe 34 and the third buffer chamber 31 are combustible gas channels; the gap between the separation pipe 39 and the isolation gas pipe 18 is a first buffer chamber 29, the first combustion-supporting pipe 36 is communicated with the first buffer chamber 29, and the inner spaces of the first buffer chamber 29 and the first combustion-supporting pipe 36 are inner combustion-supporting gas channels;
the second ventilation member 20 further has a guide tube 37 at the outer side of the partition plate 40, the guide tube 37 has a tapered structure, and the inner diameter of the guide tube 37 is smaller as the guide tube is farther from the partition plate 40;
as shown in fig. 6, 14 and 15, the outer tube 21 is sleeved on the second ventilation member 20, and the gap between the inner side wall of the outer tube 21 and the outer side wall of the second ventilation member 20 is an outer layer combustion-supporting gas channel 45, and the corresponding position of the outer tube 21 and the guide tube 37 is provided with a conical inner side wall 43, and the conical portion 33 of the outer layer combustion-supporting gas channel 45 is located between the conical inner side wall 43 and the outer side wall of the guide tube 37.
As shown in fig. 6 and 14, the outer tube 21 further includes a concave annular arc-shaped groove 44, and a space between the annular arc-shaped groove 44 and the second tube 38 is the fourth buffer chamber 32.
In this embodiment, the burner further includes:
a shielding gas inlet pipe 22 communicating with the shielding gas passage 28;
a first combustion air inlet pipe 24 communicated with a first buffer chamber 29;
a second combustion air inlet pipe 23 communicated with the second buffer chamber 30;
a gas inlet pipe 25 communicating with the third buffer chamber 31;
the third combustion-supporting gas intake pipe 26 communicates with the outer-layer combustion-supporting gas passage 45.
The circular outer layer combustion-supporting gas outlet at the outermost side of the burner of the embodiment enhances the mixing of the raw material gas and the combustion-supporting gas above the burner; the combustion-supporting gas outlets of the inner layer, the middle layer and the outer layer are matched with the central nozzle in the middle and the combustible gas outlet in the middle layer, so that the gas mixing degree can be improved, the gas can be fully combusted, the flame heat value is higher and stable, the combustible gas premixing form is more favorable for generating the reaction of easily-adsorbed agglomerated particles, and the crystallization and blockage of the raw material gas at the port can be prevented.
The raw material of the burner in the embodiment is octamethyl cyclotetrasiloxane, because the content of silicon element of octamethyl cyclotetrasiloxane accounts for about 80 percent of the total amount, compared with silicon tetrachloride raw material, the burner has the advantages that silicon dioxide dust is generated in unit time, no toxic hydrogen chloride gas is generated in byproducts of the reaction, the burner is high in cleanliness, has no pollution to the environment, not only improves the deposition efficiency, but also greatly reduces the investment and the cost of waste gas treatment.
The burner of the embodiment, the central spout is used for spraying the mixture of octamethyl cyclotetrasiloxane raw material evaporation gas and combustion-supporting gas oxygen; the isolating gas outlet is used for spraying inert isolating gas argon or nitrogen, and the purpose of the isolating gas outlet is to prevent the dust accumulation and blockage of the lamp socket; the inner layer combustion-supporting gas outlet is used for spraying combustion-supporting gas oxygen, so that the gas is fully mixed, and the flame temperature is increased; the mutually nested combustible gas outlet and the middle combustion-supporting gas outlet respectively spray the combustible gas hydrogen and the combustion-supporting gas oxygen to ignite the flame and further enhance the flame temperature; the outer layer combustion-supporting gas outlet is used for spraying the maximum amount of combustion-supporting gas oxygen and focusing in a focal length of 150-250mm from the end face of the burner, the layer determines a flame burning torch, has great influence on flame temperature, and a certain flow rate is set, so that the flame temperature can reach an optimal value, the temperature of the burning flame and the aggregation degree of generated dust particles are fully improved, and the adsorption rate of the dust particles on the optical fiber preform is increased.
The cladding of the optical fiber preform is manufactured by an OVD (over-the-counter-gas (OVD) vapor phase process, and the combustible gas, the auxiliary gas, the isolation gas and the evaporating gas of the octamethyl cyclotetrasiloxane serving as a reaction raw material are introduced into the burner of the embodiment, flame sprayed by the burner is focused on a rotating mandrel in the center, and the burner transversely and reciprocally moves relative to the mandrel at a certain speed. And under the condition of relatively high speed, the dust produced by the reaction is adsorbed on the core rod at a high speed to form an optical fiber preform blank, and after reaching a set weight or outer diameter, the deposition is stopped, and then the optical fiber preform blank is sintered into a transparent optical fiber preform in a high-temperature sintering furnace. In order to ensure that the octamethyl cyclotetrasiloxane evaporating gas is not liquefied in pipeline transportation, the heating and heat-preserving devices are wrapped outside the transportation pipeline and the burner, the combustion-supporting gas oxygen mixed with raw material gas before the burner and the insulating gas pipeline are wrapped outside the heating and heat-preserving devices, and the temperature is controlled to be 5-10 ℃ higher than the evaporating temperature.
The conventional octamethyl cyclotetrasiloxane burner was compared with the burner of this example by the OVD method, and hydrogen (H 2 ) As the combustible gas, oxygen (O 2 ) As combustion-supporting gas, argon (Ar) is used as isolating gasOctamethyl cyclotetrasiloxane (D) 4 ) As a raw material for the generation of silica dust particles, the evaporation temperature was controlled at 190 ℃, the piping temperature was controlled at 195 ℃, the burner temperature was controlled at 200 ℃, and the burner flow rate was not more than 100g/min, and the specific results are shown in table 1:
TABLE 1
Note that: in the table, each layer of air flow bit is slm, i.e. rises per minute in standard condition.
As can be seen from Table 1, the burner ports of this example did not exhibit clogging and crystallization, were flame stable, and had a relatively high temperature.
Example 2
The burners of example 1 were compared with the silicon tetrachloride burners shown in FIGS. 1 and 2 for deposition experiments, wherein both burners used hydrogen (H 2 ) As the combustible gas, oxygen (O 2 ) As a combustion supporting gas, argon (Ar) was used as a shielding gas, and octamethyl cyclotetrasiloxane (D) was used as a burner in example 1 4 ) As a raw material for the generation of silica dust particles, silicon tetrachloride (SiCl 4 ) As a raw material for the generation of silica dust particles. The two burners adopt the same reciprocating speed, the target rods adopt the same rotating speed, the air supply and exhaust speeds are also the same, and parameters such as air flow are shown in table 2:
TABLE 2
Note that: in the table above, the air flow rate of each layer is slm, and the deposition efficiency unit is g/min.
The experimental results are as follows: the temperature of the deposition surface of the target rod was graded between 1200-900 ℃ using a silicon tetrachloride burner, whereas the temperature of the deposition surface of the target rod was graded between 1500-1200 ℃ using the burner of example 1, with a higher deposition density. Deposition efficiency comparison (deposition efficiency=silica dust adsorption amount/deposition time), as shown in fig. 16, the burner of example 1 was lifted by 800% or more.
Example 3:
the burner of example 1 was compared to the octamethyl cyclotetrasiloxane burner shown in FIGS. 3 and 4 for deposition experiments, wherein both burners used hydrogen (H 2 ) As the combustible gas, oxygen (O 2 ) As combustion-supporting gas, argon (Ar) as isolating gas, octamethyltetrasiloxane (D) 4 ) As a raw material for the generation of silica dust particles. The two burners adopt the same reciprocating speed, the target rods adopt the same rotating speed, the air supply and exhaust speeds are also the same, and parameters such as air flow are shown in table 3:
TABLE 3 Table 3
Note that: in the table above, the air flow rate of each layer is slm, and the deposition efficiency unit is g/min.
The experimental results are as follows: the target rod deposition surface temperature was graded between 1300-1000 ℃ using the octamethyl cyclotetrasiloxane burner, whereas the target rod deposition surface temperature was graded between 1500-1200 ℃ using the burner of example 1, with greater deposition density. Compared with the deposition efficiency, the burner of example 1 was lifted by 20% or more as shown in fig. 17.
The foregoing description is only of the preferred embodiments of the present application, and is not intended to limit the scope of the application, but rather is intended to cover all equivalent structures as modifications within the scope of the application, either directly or indirectly, as may be contemplated by the present application.
Claims (9)
1. The burner for manufacturing the optical fiber preform is characterized by comprising a gas injection end, wherein the gas injection end sequentially comprises a central nozzle, an isolation gas outlet externally embedded on the central nozzle, a plurality of inner-layer combustion-supporting gas outlets circumferentially uniformly distributed around the isolation gas outlet, a plurality of composite gas outlets circumferentially uniformly distributed around the isolation gas outlet and an annular outer-layer combustion-supporting gas outlet from inside to outside, and the composite gas outlets comprise mutually nested combustible gas outlets and middle combustion-supporting gas outlets;
the combustible gas outlet is externally embedded on the middle combustion-supporting gas outlet, and is arranged inside the gas injection end and is spaced from the middle combustion-supporting gas outlet;
the interval means that the combustible gas outlet and the middle combustion-supporting gas outlet are not on the same plane, and a plurality of distances are arranged between the combustible gas outlet and the middle combustion-supporting gas outlet.
2. The burner for fabricating an optical fiber preform according to claim 1, wherein the central nozzle, the barrier gas outlet, the inner combustion gas outlet, the middle combustion gas outlet, and the outer combustion gas outlet are all located on the same plane.
3. The burner for manufacturing an optical fiber preform according to claim 1, further comprising a central passage, an isolation gas passage, an inner combustion gas passage, a combustible gas passage, an intermediate combustion gas passage, and an outer combustion gas passage, wherein an outlet of the central passage is a central nozzle, an outlet of the isolation gas passage is an isolation gas outlet, an outlet of the inner combustion gas passage is an inner combustion gas outlet, an outlet of the combustible gas passage is a combustible gas outlet, an outlet of the intermediate combustion gas passage is an intermediate combustion gas outlet, and an outlet of the outer combustion gas passage is an outer combustion gas outlet;
the inner layer combustion-supporting gas channel is provided with a first buffer chamber adjacent to the inner layer combustion-supporting gas outlet, the combustible gas channel is provided with a second buffer chamber adjacent to the combustible gas outlet, the middle combustion-supporting gas channel is provided with a third buffer chamber adjacent to the middle combustion-supporting gas outlet, and the outer layer combustion-supporting gas channel is provided with a fourth buffer chamber adjacent to the outer layer combustion-supporting gas outlet.
4. A burner for fabricating an optical fiber preform according to claim 3, wherein the outer combustion-supporting gas passage includes a tapered portion at an end portion, and the outer combustion-supporting gas outlet is a small diameter end of the tapered portion.
5. The burner for fabricating an optical fiber preform according to claim 4, wherein the gas injection direction of the tapered portion is at an angle of 0.5 ° to 5 ° to the central nozzle axis, and the outer layer combustion-supporting gas outlet injecting gas is focused at 150 to 250mm from the burner end face.
6. The burner for manufacturing an optical fiber preform according to claim 4, wherein a ratio of a sum of cross-sectional areas of the combustion-supporting gas outlets of the respective inner layers to a cross-sectional area of the first buffer chamber is 0.2 or less, a ratio of a sum of cross-sectional areas of the respective combustible gas outlets to a cross-sectional area of the second buffer chamber is 0.2 or less, and a ratio of a sum of cross-sectional areas of the combustion-supporting gas outlets of the intermediate layers to a cross-sectional area of the third buffer chamber is 0.2 or less; the fourth buffer chamber is of an outward protruding streamline shape, and the ratio of the maximum cross-sectional area of the fourth buffer chamber to the cross-sectional area of the combustion-supporting gas outlet of the outer layer is 8-20; the length range of each buffer chamber is more than or equal to 50mm.
7. The burner for fabricating an optical fiber preform according to claim 4, wherein the burner comprises a central tube, a spacer gas tube, a first vent, a second vent, and an outer tube;
the inner space of the central tube is a central channel, the isolating gas tube is sleeved on the central tube, and a gap between the isolating gas tube and the central tube is an isolating gas channel;
the first ventilation piece comprises a first pipe body, a cylindrical cavity is formed in the side wall of the first pipe body, the cavity is a second buffer chamber, one end of the first pipe body is provided with a plurality of second combustion-supporting pipes which are uniformly distributed around the axis direction of the first pipe body, the second combustion-supporting pipes are communicated with the second buffer chamber, and the inner spaces of the second buffer chamber and the second combustion-supporting pipes are middle combustion-supporting gas channels;
the second ventilation piece comprises a second pipe body, a partition plate is arranged at the first end of the second pipe body, the second pipe body further comprises a partition pipe penetrating through the second end of the second pipe body and fixed with the partition plate, and the second pipe body and the partition pipe are coaxially arranged; the outer end face of the partition plate is also provided with a plurality of first combustion-supporting pipes uniformly distributed around the axis direction of the second pipe body and a plurality of gas pipes uniformly distributed around the axis direction of the second pipe body, the outer side port of the first combustion-supporting pipe is an inner layer combustion-supporting gas outlet, and the height of the gas pipes is smaller than that of the first combustion-supporting pipe; the partition plate is provided with a central hole for the central pipe and the isolation gas pipe to pass through, the isolation gas pipe is sleeved in the partition pipe, and one end of the isolation gas pipe passes through the central hole; the first pipe body is sleeved in the second pipe body and sleeved on the separation pipe, the second combustion-supporting pipe penetrates through the corresponding gas pipe, the height of the second combustion-supporting pipe positioned outside the partition plate is larger than that of the gas pipe, a gap between the inner side wall of the second pipe body and the outer side wall of the first pipe body is a third buffer chamber, the gas pipe is communicated with the third buffer chamber, and the gap between the gas pipe and the second combustion-supporting pipe and the third buffer chamber are combustible gas channels; the gap between the separation pipe and the isolation gas pipe is a first buffer chamber, the first combustion-supporting pipe is communicated with the first buffer chamber, and the inner spaces of the first buffer chamber and the first combustion-supporting pipe are inner-layer combustion-supporting gas channels;
the second ventilation piece is provided with a guide pipe at the outer side of the partition board, the guide pipe is of a conical structure, and the inner diameter of the guide pipe is smaller as the guide pipe is far away from the partition board;
the outer tube is sleeved on the second ventilation piece, the gap between the inner side wall of the outer tube and the outer side wall of the second ventilation piece is an outer layer combustion-supporting gas channel, the corresponding part of the outer tube and the guide tube is provided with a conical inner side wall, and a conical part of the outer layer combustion-supporting gas channel is arranged between the conical inner side wall and the outer side wall of the guide tube.
8. The burner for manufacturing an optical fiber preform according to claim 7, wherein the outer tube further comprises an inwardly concave annular arc-shaped groove, and a space between the annular arc-shaped groove and the second tube body is a fourth buffer chamber.
9. The burner for fabricating an optical fiber preform according to claim 8, wherein the burner further comprises:
the isolation gas inlet pipe is communicated with the isolation gas channel;
the first combustion-supporting gas inlet pipe is communicated with the first cache chamber;
the second combustion-supporting gas inlet pipe is communicated with the second cache chamber;
the fuel gas inlet pipe is communicated with the third cache chamber;
and the third combustion-supporting gas inlet pipe is communicated with the outer layer combustion-supporting gas channel.
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| CN109928611B (en) * | 2017-12-18 | 2024-01-30 | 中天科技精密材料有限公司 | Burner and optical fiber preform processing device with same |
| CN108323542A (en) * | 2018-04-10 | 2018-07-27 | 肇庆市万顺达食品机械制造有限公司 | A kind of waffle oven |
| CN110966607B (en) * | 2019-12-26 | 2022-04-15 | 中天科技精密材料有限公司 | Natural gas auxiliary flame treatment burner |
| CN111559860B (en) * | 2020-05-21 | 2022-04-19 | 江苏晶隆科技有限公司 | Chemical deposition process for large-size high-purity quartz glass |
| CN114436521A (en) * | 2022-04-08 | 2022-05-06 | 武汉友美科自动化有限公司 | Device and method for preparing optical fiber preform rod by plasma chemical vapor deposition outside tube |
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| JPH1129331A (en) * | 1997-05-14 | 1999-02-02 | Nikon Corp | Production of optical member of synthetic quartz glass, and optical member |
| JP2011225413A (en) * | 2010-04-23 | 2011-11-10 | Furukawa Electric Co Ltd:The | Method for manufacturing optical fiber preform |
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| CN105384334A (en) * | 2015-11-30 | 2016-03-09 | 中天科技精密材料有限公司 | Blowtorch for large-size optical fiber perform manufacturing and large-size optical fiber perform manufacturing method of blowtorch |
| CN206447774U (en) * | 2016-12-26 | 2017-08-29 | 富通集团（嘉善）通信技术有限公司 | Manufacture the burner of preform |
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| TW440548B (en) * | 1997-05-14 | 2001-06-16 | Nippon Kogaku Kk | Synthetic silica glass optical member and method of manufacturing the same |
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| JPH1129331A (en) * | 1997-05-14 | 1999-02-02 | Nikon Corp | Production of optical member of synthetic quartz glass, and optical member |
| JP2011225413A (en) * | 2010-04-23 | 2011-11-10 | Furukawa Electric Co Ltd:The | Method for manufacturing optical fiber preform |
| CN103058510A (en) * | 2011-10-18 | 2013-04-24 | 信越化学工业株式会社 | Burner used for producing porous glass preform and method for producing porous glass preform |
| CN105384334A (en) * | 2015-11-30 | 2016-03-09 | 中天科技精密材料有限公司 | Blowtorch for large-size optical fiber perform manufacturing and large-size optical fiber perform manufacturing method of blowtorch |
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