JP2002020132A - Burner for manufacturing molten quartz glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture large-sized quartz glass ingots which are good in melting of siliceous glass powder and are free of the generation of foam with good production efficiency. SOLUTION: Gaseous hydrogen enters an annular gaseous hydrogen chamber 30 from a gaseous hydrogen supply pipe 3 and is sent along a tapered external wall 22 of a gaseous oxygen chamber 2 into a barrel 1. The gaseous hydrogen flowing down at the outer peripheral side of the barrel 1 withdraws the siliceous glass powder into gaseous hydrogen flow and is released from the aperture of the barrel 1. The gaseous hydrogen introduced by being deflected in a central direction by colliding against a gaseous hydrogen guide plate 5 is released from the aperture of the barrel 1 through the clearances of plural gaseous oxygen nozzles 21 arrayed on a concentric circle disposed on the lower side of a gaseous oxygen chamber 20 and is immediately mixed with the oxygen released from a gaseous oxyhydrogen nozzle. The oxyhydrogen flames are formed to a wide range by the hydrogen released from the outer periphery of the barrel and the hydrogen released from the clearances of the gaseous oxygen nozzles. by which the siliceous glass powder in the gaseous hydrogen flow is uniformly melted and deposited on a target and the large-sized quartz glass ingots are efficiently formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burner for producing fused silica glass, which is used for producing large-sized fused silica glass by fusing siliceous powder with a flame of a combustion gas.

[0002]

2. Description of the Related Art The flame melting method, which is one of the methods for producing quartz glass, is a method for producing quartz glass by fusing siliceous powder raw materials such as quartz and silica stone with the combustion heat of oxyhydrogen gas or propane gas. You need a burner. When a metal burner is used, along with the flame of the high-temperature combustion gas that gushes, the metal vapor or metal oxide released from the metal burner adheres to or mixes with the generated quartz glass, lowering the purity of the quartz glass. Not preferred. For this reason, a burner made of quartz glass having a structure as shown in Japanese Patent Publication No. 46-42113 shown in FIG. 7 by the present applicant is used. Although propane gas and the like can be used as the combustion gas of the flame melting method, oxyhydrogen flame fusion using hydrogen as a combustion gas is preferable from the viewpoint of purity, atmosphere control, and production of high quality quartz glass. The case will be described.

[0003]

In recent years, semiconductor wafers have been increased in size from 5 inch and 6 inch diameters to 8 inch and 12 inch diameters. As a result, quartz glass members and semiconductor wafers used in semiconductor wafer manufacturing have been increasingly used. Wafer holding / holding jigs, furnace core tubes, and various substrates to be housed and heat-treated have inevitably shifted to larger ones. Larger quartz glass ingots, which are the raw materials of these quartz glass members, are also required.

The burner disclosed in Japanese Patent Publication No. Sho 46-42113 does not supply the siliceous powder from one place at the center of the burner, but supplies the powder together with a carrier gas such as hydrogen from several places in the burner by a distribution pipe. This has the advantage that a large amount of siliceous powder can be supplied, and it has been possible to cope with an increase in the size of the quartz glass ingot to a certain extent.

In order to cope with the increase in size of the quartz glass ingot by increasing the size of the burner, the number of oxygen gas nozzles is increased by enlarging the outer cylinder, or the nozzle diameter of oxygen gas and hydrogen gas is increased by increasing the nozzle diameter of oxygen gas and hydrogen gas. And to increase the flow rate of combustion gas.

However, in the burner having the conventional structure, the hydrogen gas flow from the outer cylinder is directly discharged from the outer periphery of the outer cylinder, which is the supplied position, to the outside of the burner, and is discharged from a plurality of oxygen gas nozzles inside the outer cylinder. Was mixed with oxygen gas at a focal point (convergence point) over a considerable distance outside the burner. For this reason, the supplied oxyhydrogen gas was not entirely converted into heat, and the energy loss was large, probably because the gas was dispersed before mixing and the amount of the mixed gas contributing to combustion was reduced. Further, the focus of the oxyhydrogen gas on the burner was a point spot in accordance with the surface of the produced ingot, and a uniform molten state could not be obtained with a large ingot.

When the ingot diameter exceeds 400 mm and the supply amount of the siliceous powder is increased, the conventional burner has a structure in which the siliceous powder supply nozzle obstructs the hydrogen gas flow path. This causes turbulence, the siliceous powder is no longer uniformly dispersed in the oxyhydrogen gas stream, and the melting is uneven and bubbles are generated in the generated quartz glass, which may lead to poor quality. There was a limit in the conversion. Therefore, it has become necessary to change the structure of the burner itself to improve the efficiency of melting the siliceous powder.

The present invention improves the above-mentioned drawbacks of the conventional burner and, when producing a large quartz glass ingot, melts the silica-based powder well, generates no bubbles, and has a high production efficiency. A manufacturing burner is provided.

[0009]

In order to enhance the thermal efficiency, a region where the melting point is a surface spot is selected at a distance close to the outer cylinder opening end of the burner, and for example, oxyhydrogen gas is burned at a heating diameter of 60 mmφ. When the quartz glass was formed by heating, the surface temperature of the quartz glass did not rise, the heating diameter at the melting point was doubled, the inside became dark and discolored, and poor melting was conspicuous.

As a result of investigating the cause of the double heating diameter,
It was found that the oxygen gas was excessive in the inside compared to the outside of the melting point, in other words, the supply of hydrogen gas was insufficient. It is considered that in the conventional burner structure, hydrogen gas is hardly diffused and supplied to the inside of the burner, and this tendency is further strengthened by the increase in the number of oxygen gas nozzles accompanying the increase in size. Thus, the present invention, in which the structure of the burner is configured as follows, has been completed.

A tapered oxygen gas chamber is provided in the outer cylinder of the burner, a plurality of oxygen gas nozzles are provided at the end of the oxygen gas chamber, and a siliceous powder supply nozzle is provided between the outer cylinder and the oxygen gas chamber. Disposed so that its end is located in the outer cylinder, supply hydrogen gas along the outer wall of the oxygen gas chamber, improve the gas flow, and send a stable gas diffused with uniform directionality. Supply, and a large, high-quality quartz glass ingot can be manufactured.

The siliceous powder supply nozzles are arranged concentrically at equal intervals around the outer cylinder to prevent obstruction of the hydrogen gas flow path unlike a conventional burner, so that the raw material siliceous powder is uniformly supplied. It was to so. A plurality of oxygen gas nozzles are arranged in multiple concentric circles, a part of the hydrogen gas is introduced into the gap between the plurality of oxygen gas nozzles, and oxygen gas and hydrogen gas are mixed near the outlet of the oxygen gas nozzle, and the oxygen in the center is The excess gas state was eliminated, and uniform melting was performed.

Then, a hydrogen gas guide plate is provided between the oxygen gas nozzle and the inner wall of the outer cylinder, a part of the hydrogen gas is deflected toward the center of the burner, and a part of the hydrogen gas is introduced into the gap between the oxygen gas nozzles. In addition, the oxygen gas supply pipe has a double pipe structure,
A hydrogen gas supply pipe is provided between the inner and outer oxygen gas pipes on the concentric circle which is a double pipe to supply hydrogen, and hydrogen gas is introduced into the gap of the oxygen gas nozzle to mix oxygen and hydrogen. It was done evenly.

A hydrogen gas supply pipe is provided with a ring-shaped hydrogen gas chamber, and hydrogen gas is introduced from the ring-shaped hydrogen gas chamber into the outer cylinder along the outer wall of the oxygen gas chamber from the peripheral direction of the oxygen gas supply pipe. The amount of hydrogen supplied was stabilized to achieve uniform mixing of hydrogen and oxygen.

[0015]

EXAMPLE 1 As shown in FIG. 1, a burner made of quartz glass was provided with an outer cylinder 1.
An oxygen gas supply pipe 2, a hydrogen gas supply pipe 3, and a siliceous powder supply pipe 4 are connected to the supply port. The supply pipes are interconnected by a reinforcing rod 6 and reinforced. The oxygen gas supply pipe 2 is connected to an oxygen gas chamber 20 having a tapered diameter inside the outer cylinder 1, and an end of the oxygen gas chamber 20 extends to an intermediate portion of the outer cylinder 1, as shown in FIG. As described above, a plurality of oxygen gas nozzles 21 are arranged concentrically at the end at equal intervals, and the end of the oxygen gas nozzle 21 extends to the opening end of the outer cylinder.

The hydrogen gas supply pipe 3 is connected to a ring-shaped chamber 30 provided on the upper part of the outer cylinder 1. A plurality of distribution pipes branch from the ring-shaped chamber 30 and extend along the tapered wall surface of the oxygen gas chamber 20. It is arranged so that hydrogen gas flows.

The siliceous powder supply pipe 4 is connected to a ring-shaped chamber 40 in the same manner as the hydrogen gas, and the distribution pipe is branched into four as shown in FIG. It is connected to a siliceous powder nozzle 41 arranged at intervals. The end of the siliceous powder nozzle 41 is disposed so as to be located in the middle of the outer cylinder 1.

An annular hydrogen gas guide plate 5 is provided between the outermost oxygen gas nozzle 21 and the siliceous powder nozzle 41, and the hydrogen gas guide plate 5 is inclined toward the center of the outer cylinder 1. .

The oxygen gas enters the oxygen gas chamber 20 whose diameter has been increased in a tapered manner from the oxygen gas supply pipe 2, and the flow velocity smoothly decreases, so that the internal gas pressure fluctuates less. A fixed amount can be uniformly discharged from the plurality of oxygen gas nozzles 21 arranged.
The hydrogen gas enters the chamber 30 from the hydrogen gas supply pipe 3, is equally branched and collides with the tapered wall surface 22 of the oxygen gas chamber 20, and moves toward the outer cylinder 1 outer peripheral direction while smoothly decelerating along the wall surface 22 to diffuse. And is released from the opening of the outer cylinder 1.

A part of the hydrogen gas flowing down the tapered wall surface 22 collides with the hydrogen gas guide plate 5, is guided along the guide plate, is deflected toward the center, is guided to the gap of the oxygen gas nozzle 21, and As shown in FIG. 1, the fluid flows toward the opening of the outer cylinder 1.

The raw material siliceous powder passes through the siliceous powder supply pipe 4 and is evenly distributed in the ring-shaped chamber 40 in the outer circumferential direction of the outer cylinder 1. Riding on the hydrogen gas flow which is ejected near the center and flows downward on the outer circumference of the outer cylinder 1, the hydrogen gas flows toward the oxygen gas nozzle. The tip of the siliceous powder supply nozzle 41 is cut obliquely outward, so that the siliceous powder flows uniformly along the outer cylinder 1.

By introducing a part of the hydrogen gas into the gap between the oxygen gas nozzles 21, the hydrogen gas is
The mixture is mixed at the position discharged from 1 and an oxyhydrogen flame is formed at a short distance outside the burner. Further, since the hydrogen gas ejected from the outer peripheral portion of the outer cylinder 1 is mixed with oxygen gas to form a flame, a combination of the external mixing method and the internal mixing method is used to increase the oxyhydrogen flame width, and the thermal energy is increased. The heat loss was reduced, the heating diameter was increased, and the thermal efficiency of the burner was dramatically improved.

Embodiment 2 As shown in FIG. 4, the basic structure is the same as that of Embodiment 1. The hydrogen gas guide plate 5 extends to the outer periphery of the outer cylinder 1 and guides hydrogen gas to the outer peripheral space between the siliceous powder nozzle 41 and the outer cylinder 1. A hole 50 is provided in the hydrogen gas guide plate 5, and the tip of the siliceous powder nozzle 41 protrudes below the hydrogen gas guide plate 5 through the hole 50. Hole 5
No. 0 has a gap because it is larger than the silica powder nozzle 41, and hydrogen gas flowing into the outer cylinder through this gap is
It flows along the outer periphery in the direction of the opening, and forms a flow surrounding the oxygen gas nozzle to generate a flame. Further, the hydrogen flow guided toward the center by the hydrogen gas guide plate 5 flows through the gap of the oxygen gas nozzle 21 to the opening of the outer cylinder 1 and mixes with the oxygen gas discharged from the oxygen gas nozzle 21 immediately near the nozzle. And produce a flame.

Embodiment 3 FIGS. 5 and 6 show an oxygen gas supply pipe and a hydrogen gas supply pipe having a double structure. At the lower ends of the inner oxygen gas supply pipe 23 and the outer oxygen gas supply pipe 24, oxygen gas chambers 25 and 26 having tapered diameters are provided, respectively. And is discharged from the oxygen gas nozzle 21 provided below them. The siliceous powder is branched into four portions from the siliceous powder supply pipe 4 via a ring-shaped chamber, and is uniformly diffused and discharged into the outer cylinder 1 from the siliceous powder nozzle 41.

The hydrogen gas is sent from the outer hydrogen gas supply pipe 32 along the tapered outer wall of the outer oxygen gas chamber 26 into the outer cylinder 1, and is discharged from the siliceous powder nozzle 41 at the outer periphery of the outer cylinder 1. The siliceous powder is drawn into the hydrogen gas flow, and is discharged from the opening of the outer cylinder 1 while promoting the dispersion and diffusion of the powder. The hydrogen gas is sent from the inner hydrogen gas supply pipe 31 provided between the inner and outer oxygen gas supply pipes 23 and 24 along the tapered outer wall of the inner oxygen gas chamber 25, and is sent to the gap of the oxygen gas nozzle 21. It is introduced and released from the opening of the outer cylinder 1.

[0026]

[Production Example] Silica powder, silica sand, quartz powder and the like are used as the silica powder as the raw material of the fused silica glass ingot. When producing a high-purity product, one kind of a high-purity silicon oxide source such as α-quartz or cristobalite, or a mixture thereof is used. For example, purified high-purity quartz powder or silicon alkoxide is hydrochloric acid, or calcined silica obtained by hydrolysis under an ammonia catalyst, and silica obtained by reacting an alkali metal silicic acid aqueous solution with an acid is purified. Such as fired.

In the case of the oxyhydrogen flame melting method, the ratio of the supplied oxyhydrogen gas is made to be an excess of hydrogen over the stoichiometrically required amount, so that the produced quartz glass has an improved heat retaining effect and the molten state is improved. It is preferable in order to improve. Further, the melting atmosphere becomes a reducing atmosphere, which has an effect of preventing deterioration and the like due to oxidative consumption of furnace materials and the like. Hydrogen gas / oxygen gas molar ratio is 2.1 to
2.5, more preferably 2.2 to 2.4.

Production Example 1 Oxygen gas nozzle 21 of the quartz glass burner of Example 1
With a diameter of 6 mmφ and 35
The molar ratio of hydrogen gas to oxygen gas (H _Two/ O_Two)
Is 2.3, and the quartz powder melted in a mist
Spraying on a rotating target, melting and depositing
Lower at a constant speed while rotating, 480mmφ × 90
A 0 mm column-shaped quartz glass ingot was obtained.

Production Example 2 The quartz glass burner of Example 2 was used as a main burner, and quartz powder melted by an oxyhydrogen flame having a molar ratio of hydrogen gas to oxygen gas of 2.2 was deposited in a rotating container. The quartz glass was heated with a sub-burner of oxyhydrogen gas having a molar ratio of hydrogen gas to oxygen gas of 2.3, and the generated quartz glass was flowed and extended in the outer peripheral direction of the container to 950 mm × 95.
A square plate-shaped quartz glass ingot (slab) of 0 mm × 400 mm was obtained.

In both Production Example 1 and Production Example 2, there was no generation of aggregated foam or crown foam in which the upper cup area of the ingot became opaque. there were. In addition, since the combustion efficiency is improved, the average amount of raw material supplied per hour can be increased. Conventionally, in the production of slabs, the raw material supply rate is 1.0 to 10 kg depending on the use and shape of the quartz glass to be produced. /
Although it was Hr, it is possible to double the supply rate per hour, for example, from 2.0 kg / Hr to 4.0 kg / Hr without causing deterioration in quality,
A large fused silica glass ingot could be manufactured with good production efficiency.

[0031]

The siliceous powder supply nozzle is arranged between the outer cylinder and the oxygen gas chamber, and the end of the nozzle is located in the outer cylinder. It can be diffused and supplied, and a part of the hydrogen gas is deflected to the center by the hydrogen gas guide plate and guided between the oxygen gas nozzles, so that the hydrogen gas can be uniformly supplied to the oxygen gas in a well-balanced manner. A stable flame with a large diameter can be obtained, and the flame can be efficiently heated and reacted with the siliceous powder, there is no generation of bubbles, and the loss of heat energy is suppressed to produce a large quartz glass ingot with high production efficiency. It became possible.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a first embodiment.

FIG. 2 is a plan view of the first embodiment.

FIG. 3 is a bottom view of the first embodiment.

FIG. 4 is a perspective view of a second embodiment.

FIG. 5 is a front sectional view of a third embodiment.

FIG. 6 is a plan view of a third embodiment.

FIG. 7 is a front sectional view of a conventional quartz glass burner.

[Explanation of symbols]

 Reference Signs List 1 outer cylinder 2 oxygen gas supply pipe 3 hydrogen gas supply pipe 4 siliceous powder supply pipe 5 hydrogen gas guide plate 30, 40 ring-shaped chamber 20 oxygen gas chamber 21 oxygen gas nozzle 22 tapered wall surface 41 siliceous powder nozzle

Claims (6)

[Claims] 1. An outer cylinder, a tapered oxygen gas chamber provided at the center of the outer cylinder and connected to an oxygen supply pipe, a plurality of oxygen gas nozzles provided at an end of the oxygen gas chamber, and an outer cylinder. Placed between oxygen gas chambers,
A fused silica glass manufacturing burner comprising a silica glass powder supply nozzle having an end located in an outer cylinder and a hydrogen gas supply pipe connected to supply hydrogen gas along an outer wall of an oxygen gas chamber. 2. The burner for producing fused silica glass according to claim 1, wherein the siliceous powder supply nozzles are provided at equal intervals on the circumference. 3. The method according to claim 1, wherein the oxygen gas nozzles are arranged in multiple concentric circles, and a part of the hydrogen gas is introduced into the gap between the oxygen gas nozzles. burner. 4. A burner for producing fused silica glass according to claim 3, wherein a part of the hydrogen gas is deflected to the center of the burner by the hydrogen gas guide plate. 5. The burner for producing fused silica glass according to claim 3, wherein the oxygen gas supply pipe has a double pipe structure, and a hydrogen gas supply pipe is provided between oxygen gas pipes of the double pipe structure. 6. The hydrogen gas supply pipe according to any one of claims 1 to 5, wherein the hydrogen gas supply pipe is connected to a ring-shaped chamber, and a plurality of distribution pipes from the ring-shaped chamber supply hydrogen gas along an outer wall of the oxygen gas chamber. Burner for producing fused silica glass to be introduced into the interior.