A three-stage flame VAD process deposition torch

Abstract

The present invention relates to a three-stage flame VAD process deposition torch, comprising a torch body, a central feed hole and multiple layers of annular air holes surrounding the central feed hole are arranged in the circumferential direction of the torch body, characterized in that the multiple layers of annular air holes are all flame annular air holes, and sequentially include inner flame annular air holes, middle flame annular air holes and outer flame annular air holes from the inside to the outside, and the nozzle end face of the torch body is three-stage axially increasing concave from the inside to the outside, wherein the nozzle of the inner flame annular air hole is located at the innermost surface of the nozzle end face, flush with the nozzle of the central feed hole, the nozzle of the middle flame annular air hole is located at the second innermost surface of the nozzle end face, and the nozzle of the outer flame annular air hole is located at the outermost surface of the nozzle end face, and the flame annular air holes include oxygen annular air holes and hydrogen annular air holes. The present invention not only has a reasonable structure and is easy to process, but also can effectively improve and increase the collection rate and deposition rate of the deposition process.

Description

Technical Field

[0001] The invention relates to a three-stage flame VAD process deposition torch, belonging to the technical field of optical fiber preform manufacturing. Background Art

[0002] The manufacturing process of optical fiber preform is the most advanced and core technology in the entire optical fiber industry. Currently, the known manufacturing processes of optical fiber preform include the in-tube vapor deposition process and the out-tube vapor deposition process. The out-tube vapor deposition processes include OVD (outside vapor deposition) and VAD (vapor axial deposition). The VAD process uses raw gas and hydrogen flame to react to produce SiO2 and GeO2 powder, which are deposited on a predetermined target rod. By controlling the position of the flame torch and adjusting the amount of each reaction gas, the optical fiber preform powder rod with uniform outer diameter can be deposited. The VAD process has high production efficiency, simple production control, low cost, and is conducive to large-scale production. It is the mainstream process route on the market. The structure and performance of the VAD process deposition torch are very important to improve the production efficiency and process control of the VAD process. The structural design of the existing VAD process deposition torch is not entirely reasonable, resulting in insufficient combustion reaction and the deposition efficiency needs to be further improved. The torch is usually made of metal and glass materials, which often require high structural precision, are difficult to process, and repeatability cannot be guaranteed. This not only brings inconvenience to actual operation, but also makes the process unstable, affecting deposition efficiency and quality. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a three-stage flame VAD process deposition torch in view of the deficiencies in the above-mentioned prior art, which not only has a reasonable structure and is easy to process, but also can effectively improve and enhance the collection rate and deposition rate of the deposition process.

[0004] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows: it includes a blowtorch body, a central feed hole and multiple layers of annular air holes are arranged circumferentially on the blowtorch body around the central feed hole, characterized in that the multiple layers of annular air holes are all flame annular air holes, and from the inside to the outside, they include inner flame annular air holes, middle flame annular air holes and outer flame annular air holes in sequence, the nozzle end face of the blowtorch body is three-level axially increasing concave from the inside to the outside, wherein the nozzle of the inner flame annular air hole is located at the innermost surface of the nozzle end face, flush with the nozzle of the central feed hole, the nozzle of the middle flame annular air hole is located at the second innermost surface of the nozzle end face, and the nozzle of the outer flame annular air hole is located at the outermost surface of the nozzle end face, and the flame annular air holes include oxygen annular air holes and hydrogen annular air holes.

[0005] According to the above solution, the burner body is made of titanium alloy.

[0006] According to the above scheme, the height of the outermost layer of the inner flame annular air hole is flush with the second inner surface of the nozzle end face, and the inner surface of the outer ring is inlaid with an inner ceramic inner ring, forming the first-stage flame combustion mixing chamber of the blowtorch, the height of the outermost layer of the middle flame annular air hole is flush with the outermost surface of the nozzle end face, and the inner surface of the outer ring is inlaid with an outer ceramic inner ring, forming the second-stage flame combustion mixing chamber of the blowtorch, and the height of the end faces of each layer of the outer flame annular air hole is flush with the outermost surface of the nozzle end face, forming the third-stage flame combustion mixing zone of the blowtorch.

[0007] According to the above scheme, arc-shaped blocks are arranged in the flame annular air holes to form grid-shaped flame annular air holes, and part or all of the flame annular air holes are arranged as grid-shaped flame annular air holes.

[0008] According to the above scheme, 3 to 6 arc-shaped blocks are provided, which are arranged at intervals along the circumferential direction in the annular air hole corresponding to the air inlet holes.

[0009] According to the above scheme, the inner flame annular pores include 1 to 2 inner oxygen annular pores and 1 to 2 inner hydrogen annular pores.

[0010] According to the above scheme, the middle flame annular pores include 1 to 2 layers of middle hydrogen annular pores arranged inside and 0 to 1 layers of middle oxygen annular pores arranged outside.

[0011] According to the above scheme, the outer flame annular pores include 0 to 1 layers of outer hydrogen annular pores arranged inside and 1 to 3 layers of outer oxygen annular pores arranged outside.

[0012] According to the above scheme, the flame annular air holes are concentric annular air holes, the radial single-side width of the annular air holes is 1 to 3 mm, and the front end of each layer of flame annular air holes is a nozzle and the rear end is closed.

[0013] According to the above scheme, the oxygen flow rate of the oxygen annular pore is 10-20 slm, and the hydrogen flow rate of the hydrogen annular pore is 30-50 slm.

[0014] According to the above scheme, the rear end of the blowtorch body is in the shape of an outwardly convex step, the outer ring of the flame annular air hole increases layer by layer along the axial direction from the outside to the inside, and an air inlet connected to the annular air hole is arranged on one side of the rear end of each layer of the outer ring of the flame annular air hole.

[0015] The beneficial effects of the present invention are as follows: 1. A three-stage flame combustion zone is set, the three-stage flame heating temperature is high, the flame reaction zone is about 30% longer than that of an ordinary blowtorch, the SiO2 deposition particle density generated by the reaction is high, and the collection rate and deposition rate are high; 2. The blowtorch body is made of titanium alloy, which is easy to process and has low cost compared to glass materials. Compared with other metals, it has high temperature resistance and acid and alkali corrosion resistance and is suitable for harsh production environments; a two-stage ceramic inner ring insulation sheath is used to isolate and guide the internal and external graded flames to avoid the corresponding inner layer of the pipe wall being baked and deformed by high temperature; at the same time, different levels of flames A ceramic inner sleeve is used for isolation. Compared with the traditional inert isolation gas method, it can not only achieve the flame laminar steady-state and thermal insulation effect, but also save gas consumption and the cost of isolation gas; 3. The diversion grid structure of the three-layer flame and the annular air hole reduces the impact effect near the air inlet, has a better diversion effect, and the actual flame airflow state is more inclined to the laminar structure, which reduces the risk of turbulence, improves the stability of the deposition process, and is more conducive to the production of large-size powder rods; 4. The structure is reasonably set up, easy to process, and suitable for large-scale batch customization; it is easy to operate and has high processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a front cross-sectional structural diagram of an embodiment of the present invention.

[0017] Figure 2 It is a front cross-sectional structural diagram of another embodiment of the present invention.

[0018] Figure 3 The top view of the structure of a layer of annular pores in one embodiment of the present invention.

[0019] Figure 4 It is a three-dimensional structural diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are further described below with reference to the accompanying drawings.

[0021] The first implementation is Figure 1 , 3As shown in , 4, it is a blowtorch with three levels and five layers of flame annular air holes, including a blowtorch body, a central feed hole 8 is arranged along the circumferential direction of the blowtorch body, the central feed hole is connected with the feed gas source, and mainly sprays silicon tetrachloride and germanium tetrachloride mixed vapor, and multiple layers of concentric annular air holes are arranged around the central feed hole, the multiple layers of annular air holes are all flame annular air holes, and include inner flame annular air holes, middle flame annular air holes and outer flame annular air holes from the inside to the outside, the inner flame annular air holes include 1 inner oxygen annular air holes 1 and 1 inner hydrogen annular air holes 2 arranged outside; the middle flame annular air holes include 1 middle hydrogen annular air holes 3; the outer flame annular air holes include 2 outer oxygen annular air holes 4, 5. The nozzle end face of the blowtorch body presents a three-level axially increasing concave shape from the inside to the outside, wherein the inner flame annular air hole nozzle is located at the innermost surface of the nozzle end face and is flush with the central feed hole nozzle, the middle flame annular air hole nozzle is located at the sub-inner surface of the nozzle end face, and the outer flame annular air hole nozzle is located at the outermost surface of the nozzle end face. The blowtorch body is made of titanium alloy, the outer circle height of the outermost layer of the inner flame annular air hole, that is, the outer circle height of the inner hydrogen annular air hole 2 is flush with the sub-inner surface of the nozzle end face, and the inner surface of the outer circle is inlaid with an inner ceramic inner circle 7, forming a first-level flame combustion mixing chamber of the blowtorch, the outer circle height of the outermost layer of the middle flame annular air hole, that is, the outer circle height of the middle hydrogen annular air hole 3 is flush with the outermost surface of the nozzle end face, and the inner surface of the outer circle is inlaid with an outer ceramic inner circle 6, forming a second-level flame combustion mixing chamber of the blowtorch, and the end surface heights of each layer of the outer flame annular air hole are flush with the outermost surface of the nozzle end face, forming a third-level flame combustion mixing zone of the blowtorch. The flame annular air holes are provided with arc blocks to form grid-shaped flame annular air holes. All the flame annular air holes are set as grid-shaped flame annular air holes. Four arc blocks are set in each layer of flame annular air holes. They are arranged at intervals along the circumference in the annular air holes corresponding to the air inlet holes. An arc block with a smaller arc is set above the air inlet hole, and an arc block 9 with a larger arc is set opposite the air inlet hole. Arc blocks with the smaller arc are set at intervals of one arc on both sides of the air inlet hole. The radial single-side width of the annular air holes described in this embodiment is 1 to 3 mm. The front end of each layer of flame annular air holes is a nozzle and the rear end is closed. The oxygen flow rate of the oxygen annular air holes is 10 to 20 slm, and the hydrogen flow rate of the hydrogen annular air holes is 30 to 50 slm. The rear end of the burner body is in an outward convex step shape. The outer ring of the flame annular air holes increases layer by layer along the axial direction from the outside to the inside. An air inlet connected to the annular air hole is set on one side of the rear end of the outer ring of each layer of flame annular air holes. The outer diameter of the blowtorch is approximately 65mm.

[0022] The second implementation example Figure 2, as shown in FIG3 , is a three-level seven-layer flame annular air hole blowtorch, which is different from the first embodiment in that the middle flame annular air hole is a two-layer annular air hole, including a middle layer hydrogen annular air hole 3 arranged inside and a middle layer oxygen annular air hole 10 arranged outside; the outer flame annular air hole is a three-layer annular air hole, including an outer layer hydrogen annular air hole 11 arranged inside and two outer layers of oxygen annular air holes 4 and 5 arranged outside. The outer diameter of the blowtorch is about 70mm. The rest of the structure is the same as the previous embodiment, which can improve the reaction temperature and reaction efficiency.

[0023] The present invention can also be configured as a blowtorch with three levels and nine layers of flame annular air holes, wherein the middle layer of flame annular air holes is a three-layer annular air hole, and the outer layer of flame annular air holes is a four-layer annular air hole.

[0024] Table 1 is the deposition powder rod parameter results of the present invention:

[0025] Table 1 Deposition powder rod parameter results

[0026] Powder rod diameter Collection rate Powder stick density Deposition rate mm mm G / cm^3 G / min 150 70％ >0.35 8 200 72％ >0.35 10 230 75％ >0.35 12

[0027] The results of the embodiment show that compared with the traditional two-stage or single-stage metal / glass blowtorch, the collection rate is increased by 5%, up to 75%, the deposition rate can reach 12g / min, and the outer diameter of the powder rod can reach more than 230mm; the powder rod density is increased by 15% compared with the traditional blowtorch, up to 0.35g / cm 3 The overall production efficiency is increased by more than 10% compared with traditional blowtorches.

Claims

1. A three-stage flame VAD process deposition torch, comprising a torch body, wherein the torch body is provided with a central feed hole and multiple layers of annular air holes surrounding the central feed hole along the circumferential direction, characterized in that The multi-layer annular air holes are all flame annular air holes, and include inner flame annular air holes, middle flame annular air holes and outer flame annular air holes from the inside to the outside. The nozzle end face of the burner body is three-level axially increasing inward concave from the inside to the outside, wherein the inner flame annular air hole nozzle is located at the innermost surface of the nozzle end face, flush with the central feed hole nozzle, the middle flame annular air hole nozzle is located at the second inner surface of the nozzle end face, and the outer flame annular air hole nozzle is located at the outermost surface of the nozzle end face. The flame annular air holes include oxygen annular air holes and hydrogen annular air holes; the outer circle height of the outermost layer of the inner flame annular air holes is flush with the second inner surface of the nozzle end face, and the inner surface of the outer circle is inlaid with an inner ceramic inner circle, forming the first-stage flame combustion mixing chamber of the blowtorch; the outer circle height of the outermost layer of the middle flame annular air holes is flush with the outermost surface of the nozzle end face, and the inner surface of the outer circle is inlaid with an outer ceramic inner circle, forming the second-stage flame combustion mixing chamber of the blowtorch; the end surface heights of each layer of the outer flame annular air holes are flush with the outermost surface of the nozzle end face, forming the third-stage flame combustion mixing zone of the blowtorch.

2. The three-stage flame VAD process deposition torch according to claim 1, characterized in that The blowtorch body is made of titanium alloy.

3. The three-stage flame VAD process deposition torch according to claim 1 or 2, characterized in that An arc-shaped stopper is arranged inside the flame annular air hole to form a grid-shaped flame annular air hole, and part or all of the flame annular air hole is arranged as a grid-shaped flame annular air hole.

4. The three-stage flame VAD process deposition torch according to claim 3, characterized in that The arc-shaped stoppers are arranged in 3 to 6 pieces and are arranged at intervals along the circumferential direction in the annular air hole corresponding to the air inlet holes.

5. The three-stage flame VAD process deposition torch according to claim 1, characterized in that The inner flame annular pores include 1 to 2 inner oxygen annular pores and 1 to 2 inner hydrogen annular pores.

6. The three-stage flame VAD process deposition torch according to claim 5, characterized in that The middle-layer flame annular pores include 1-2 layers of inner middle-layer hydrogen annular pores and 0-1 layers of outer middle-layer oxygen annular pores.

7. The three-stage flame VAD process deposition torch according to claim 6, characterized in that The outer flame annular pores include 0 to 1 layers of outer hydrogen annular pores arranged inside and 1 to 3 layers of outer oxygen annular pores arranged outside.

8. The three-stage flame VAD process deposition torch according to claim 1 or 2, characterized in that The flame annular air holes are concentric annular air holes, the radial single-side width of the annular air holes is 1-3 mm, the front end of each layer of flame annular air holes is a nozzle, and the rear end is closed.

9. The three-stage flame VAD process deposition torch according to claim 7, characterized in that The oxygen flow rate of the oxygen annular air hole is 10-20slm, and the hydrogen flow rate of the hydrogen annular air hole is 30-50slm; the rear end of the burner body is in an outwardly convex step shape, and the outer ring of the flame annular air hole increases layer by layer along the axial direction from the outside to the inside, and an air inlet hole connected to the annular air hole is arranged on one side of the rear end of each layer of the outer ring of the flame annular air hole.

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