JPH033615B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for producing synthetic glass for communications and optical applications.

``Prior Art'' OVD is one of the methods for producing glass rods, glass pipes, etc. for communication and optical applications made of high-grade synthetic quartz.

As is known, in the OVD method, soot-like glass particles (SiO ₂ , GeO ₂ , P ₂ O ₅ , B ₂ O ₃ , etc.) generated by flame hydrolysis reaction and/or thermal oxidation reaction are called the starting base material. deposited on the outer periphery of the glass deposition substrate to form a porous glass layer;
The porous glass layer is heated and defoamed to become transparent glass.

More specifically, during the deposition formation of the porous glass layer, a burner for producing glass particles and a glass deposition base that reciprocates in the axial direction while rotating are placed in a reaction vessel having a gas introduction system and a gas exhaust system. The glass particles are arranged in a manner that corresponds to each other, and the glass fine particles produced by the reaction are deposited on the outer periphery of the glass deposition base material through a burner.

In the case of this OVD method, compared to the VAD method in which the porous glass layer is grown in the axial direction (in the shape of a vertically long rod),
It is said that the porous glass layer is unlikely to break due to its own weight.

``Problems to be solved by the invention'' In the case of the above-mentioned OVD method, the raw material gas is mainly
Since chlorides such as SiCl ₄ , GeCl ₄ , POCl ₃ , and BCl ₃ are used, these reaction gases contain a large amount of corrosive gases such as Cl ₂ and HCl.

The reaction gas in the reaction vessel is discharged as waste gas from the gas exhaust system to the outside of the vessel and undergoes treatment to remove harmful components, but an unexpected abnormality occurs in the gas exhaust system and the exhaust capacity decreases. In this case, the reaction vessel is filled with waste gas.

Even if there is no particular abnormality in the gas exhaust system, waste gas may back-diffuse from the gas exhaust system into the reaction vessel due to pressure fluctuations inside and outside the reaction vessel.

Therefore, the inside of the reaction vessel is contaminated by the waste gas, and especially when the reaction vessel is not sufficiently airtight, the surrounding environment is deteriorated by the waste gas leaking from the reaction vessel.

Of course, since the waste gas contains the above-mentioned corrosive components, it can rust the metal parts of equipment and have an adverse effect on the human body.

On the other hand, a high level of cleanliness is required inside the reaction vessel in order to obtain high-quality synthetic quartz, but the inside of the reaction vessel, which is sucked in through the gas exhaust system, constantly tends to have a negative pressure. If the airtightness of the reaction vessel is insufficient, external dust and the like will enter as impurities and reduce the cleanliness inside the reaction vessel, making it difficult to maintain the above-mentioned quality.

In view of the above-mentioned problems, the present invention can prevent gas leakage from a reaction vessel to the outside thereof, and contamination of impurities from the outside into the reaction vessel. Furthermore, the present invention aims to provide an apparatus capable of producing high quality synthetic glass.

"Means for Solving the Problems" In order to achieve the above object, the present invention provides a system in which a burner for producing glass fine particles and a glass deposition substrate are mutually connected in a reaction vessel having a gas introduction system and a gas exhaust system. In a synthetic glass manufacturing apparatus equipped with an interior corresponding to It is characterized by being provided with a gas adjustment mechanism that can relatively adjust the gas pressure inside the container and the gas pressure in the internal space of the double-walled body.

``Operation'' In the case of the device of the present invention, on the outer periphery of the glass deposition substrate that reciprocates in a predetermined direction while rotating within the reaction vessel,
Glass particles produced by the reaction are deposited through a burner, thereby forming a porous glass layer.

At this time, the inside of the reaction vessel is evacuated via the gas exhaust system, and at the same time, clean gas is introduced into the reaction vessel from the gas introduction system.

Formation of the porous glass layer, gas discharge, gas introduction, etc. are the same as in the conventional example.

In the apparatus of the present invention, the reaction vessel (part or all) used when forming the porous glass layer as described above is
is composed of a double-walled body with an internal space,
Moreover, the gas pressure outside the reaction vessel P ₁
A gas adjustment mechanism is provided which can relatively adjust the gas pressure P ₃ inside the reaction vessel and the gas pressure P ₂ inside the double-walled body.

Therefore, even if the airtightness of the reaction vessel is insufficient, P ₁ < P ₃ <
By satisfying P ₂ or satisfying P ₂ < P ₁ and P ₂ < P ₃ , gas leakage from inside the reaction vessel to the outside, impurity contamination from the outside into the reaction vessel, and gas exhaust system can be prevented. Back diffusion of waste gas into the reaction vessel can be prevented, and a high-quality porous glass layer can be stably produced.

``Embodiments'' Examples of the apparatus of the present invention will be described below with reference to the drawings.

In the figure, a reaction vessel 1 made of quartz glass or ceramics has gas introduction systems 2a, 2b and a gas exhaust system 3.

In some cases, the material constituting the reaction vessel 1 may be resin-coated quartz glass, ceramics, or the like, and the resin coating material may be fluorine resin, silicone resin, or the like.

The gas introduction systems 2a and 2b are equipped with filters 4a and 4b, and these filters 4a and 4b have a function of filtering outside air to a cleanliness level of about 0 to 100 class.

The gas introduction systems 2a and 2b include inert gas cylinders (not shown) for introducing gas into the reaction vessel 1;
Alternatively, a cylinder of clean air (cleanliness class 0 to 100) may be connected via piping, but in this case, the filters 4a and 4b may be omitted.

The gas exhaust system 3 includes a waste gas harmful component removal tank 5 and a suction type exhaust fan 6, and the harmful component removal tank 5 has a function of causing a cleaning liquid such as water or alkaline solution to flow countercurrently to the waste gas.

Inside the reaction vessel 1 are a vertical downward glass particle generation burner 7 and a horizontal (horizontal) glass deposition substrate 8.
and are decorated in correspondence with each other.

The burner 7 has, for example, a multi-tube structure having a plurality of gas passages arranged concentrically, and predetermined gas pipes are respectively connected to these gas passages.

The glass deposition substrate 8, which can be rotated and reciprocated in the axial direction via a rotation means and a reciprocating means (not shown), is made of a quartz rod or a quartz tube, and both ends of the deposition substrate 8 are protruded outside the reaction vessel 1. Chuck 9a, 9
It is supported through b.

The glass deposition substrate 8, including the chucks 9a, 9b, their rotation means, reciprocating means, etc., may be housed in the reaction vessel 1 in its entirety.

Further, as shown in the figure, when the base end of the gas exhaust system 3, the gas supply pipe to the burner 7, both ends of the glass deposition substrate 8, etc. penetrate the wall surface of the reaction vessel 1, sealing means is provided at these penetrating portions. will be taken.

In the present invention, in the synthetic glass manufacturing apparatus having such a structure, the entire reaction vessel 1 (or even a part thereof) is constituted by a double-walled body 11 having an internal space 10.

An air supply system 12 communicating with the internal space 10 and an exhaust system 14 having a pressure regulating valve 13 are connected to the double wall body 11, respectively.

The air supply system 12 is equipped with a filter (filtration function: cleanliness level 0 to
100 class), or an inert gas cylinder, or clean air (cleanliness level 0~
100 class) cylinders are connected by piping.

Furthermore, as described above, the apparatus of the present invention has a gas adjustment system that allows the gas pressure inside the reaction container 1 and the gas pressure in the internal space 10 of the double-walled body 11 to be adjusted relative to the gas pressure outside the reaction container 1. Equipped with a mechanism.

Part of the gas adjustment mechanism includes the gas introduction systems 2a and 2b, the gas exhaust system 3, the air supply system 12, and the exhaust system 14 described above.

The other parts of the gas adjustment mechanism include a pressure gauge 15 for measuring the gas pressure outside the reaction vessel 1, and an internal space 1.
A pressure gauge 16 for measuring the gas pressure at 0, and a pressure gauge 17 for measuring the gas pressure inside the reaction vessel 1.
and a control device 18 for controlling the gas pressure in the reaction vessel 1 and the gas pressure in the internal space 10, the pressure gauge 15 is disposed outside the reaction vessel 1, and the sensor 19 of the pressure gauge 16 is located in the interior space 10. The sensor 20 of the pressure gauge 17 is placed inside the reaction vessel 1 .

The control device 18 adjusts the gas pressure in the reaction vessel 1 and the gas pressure in the internal space 10 to predetermined values based on the measured value input from each pressure gauge 15 to 17. It has a function of controlling part or all of the exhaust system 3, air supply system 12, and exhaust system 14.

More specifically, the control device 18 has a function of controlling at least the exhaust fan 6 of the gas exhaust system 3 and the pressure regulating valve 13 of the exhaust system 14.

In the case of the apparatus of the present invention described above, the glass deposition substrate 8 is rotated and reciprocated in the axial direction within the reaction vessel 1, as in the conventional example, and the burner 7 having a multi-tubular structure is filled with, for example, SiCl ₄ , Ar, O _{2 .} , _H2 etc.,
Glass particles generated by a predetermined reaction of each of these gases are deposited on the outer periphery of the glass deposition substrate 8 to form a quartz-based porous glass layer 21.

When manufacturing synthetic glass in this way, not only the gas introduction systems 2a and 2b and the gas exhaust system 3 are operated, but also the air supply system 12 and the exhaust system 14 are operated,
Moreover, at this time, the gas pressure P ₁ outside the reaction vessel 1, the gas pressure P ₂ in the internal space 10, and the gas pressure P ₃ inside the reaction vessel 1.
etc. are measured via the pressure gauges 15 to 17, and these measurement results are input to the control device 18, and the control device 18 controls the exhaust fan 6 of the gas exhaust system 3 and the pressure regulating valve 13 of the exhaust system 14. By controlling the
The above pressures may be set to "P ₁ < P ₃ < P ₂ ", or "P ₂ < P ₁ , P ₂ < P ₃ ".

In this way, the gas inside the reaction vessel 1 will not leak to the outside, or impurities will not be mixed into the reaction vessel 1 from the outside, and each system will exhibit an extremely stable operating condition.

As a result, the cleanliness inside the reaction vessel 1 is maintained well, a high quality porous glass layer 21 is obtained, and the surrounding working circulation is not contaminated.

``Effects of the Invention'' As explained above, according to the present invention, part or all of the reaction vessel in a predetermined synthetic glass manufacturing apparatus is constituted by a double-walled body having an internal space, and the reaction vessel is Since a gas adjustment mechanism is provided that allows relative adjustment of the gas pressure inside the reaction vessel and the gas pressure in the internal space of the double-walled body with respect to the external gas pressure, the gas pressure inside the reaction vessel is adjusted via the gas adjustment mechanism. By adjusting the gas pressure in the internal space of the double-walled body to an appropriate state, it is possible to prevent gas leakage from the reaction vessel to the outside, and to prevent impurities from entering the reaction vessel from the outside. High-quality synthetic glass can be manufactured stably without contaminating the working environment.

[Brief explanation of the drawing]

The drawing is a sectional view schematically showing an embodiment of a glass synthesis apparatus according to the present invention. 1... Reaction container, 2a, 2b... Gas introduction system,
3... Gas exhaust system, 6... Exhaust fan, 7... Burner for generating glass particles, 8... Glass deposition base material, 10... Internal space of double wall body, 11... Double wall body, 12...Air supply system, 13...Exhaust system pressure regulating valve, 14...Exhaust system, 15-17...Pressure gauge,
18...Control equipment, 19, 20...Pressure gauge sensor, 21...Porous glass layer, _P1 ...Gas pressure outside the reaction vessel, _P2 ...Gas pressure in the internal space, _P3 ...
...Gas pressure inside the reaction vessel.

Claims (1)

[Scope of Claims] 1. A synthetic glass manufacturing apparatus in which a burner for producing glass fine particles and a glass deposition substrate are installed in a reaction vessel having a gas introduction system and a gas exhaust system in correspondence with each other, Part or all of the reaction vessel is composed of a double-walled body having an internal space, and the reaction vessel has a gas pressure inside the reaction vessel with respect to a gas pressure outside the reaction vessel, and a pressure inside the double-walled body. A synthetic glass manufacturing apparatus characterized by being provided with a gas adjustment mechanism capable of relatively adjusting gas pressure. 2. The gas adjustment mechanism controls the gas introduction system and gas exhaust system provided in the reaction vessel, the air supply system and exhaust system provided in communication with the internal space of the double-walled body, and the gas pressure inside and outside the reaction vessel. Claims consisting of a pressure gauge for measuring the gas pressure in the internal space of the double-walled body, and a control device for controlling the gas pressure inside the reaction vessel and the gas pressure in the internal space of the double-walled body The synthetic glass manufacturing apparatus according to item 1. 3 The gas pressure outside the reaction vessel is P ₁ , the gas pressure inside the double-walled body is P ₂ , and the gas pressure inside the reaction vessel is P 1 .
The synthetic glass manufacturing apparatus according to claim 1, wherein these gas pressures satisfy the relationship P ₁ < P ₃ < P ₂ when P ₃ . 4 The gas pressure outside the reaction vessel is P ₁ , the gas pressure inside the double-walled body is P ₂ , and the gas pressure inside the reaction vessel is P 1 .
When P ₃ , these gas pressures are P ₂ < P ₁ , P ₂ < P ₃
A synthetic glass manufacturing apparatus according to claim 1, which satisfies the following relationship. 5. The synthetic glass manufacturing apparatus according to any one of claims 1 to 4, wherein the gas pressure in the internal space of the double-walled body is positive pressure. 6. The synthetic glass manufacturing apparatus according to any one of claims 1 to 4, wherein the gas introduced into the reaction vessel is an inert gas, clean air, or a mixed gas thereof. 7. The synthetic glass manufacturing apparatus according to any one of claims 1 to 5, wherein the gas introduced into the internal space of the double-walled body is an inert gas, clean air, or a mixed gas thereof. 8. The synthetic glass manufacturing apparatus according to claim 6 or 7, wherein the clean air has a cleanliness level of 0 to 100 class. 9. The synthetic glass manufacturing apparatus according to any one of claims 1 to 4 or 6, wherein the reaction vessel is made of an arbitrary material selected from quartz glass and ceramics. 10. The synthetic glass manufacturing apparatus according to any one of claims 1 to 4, 6, or 9, wherein the material for the reaction vessel is coated with a resin. 11. The synthetic glass manufacturing apparatus according to claim 9, wherein the resin coating material is made of either fluororesin or silicone resin.