JP6714849B2 - Sintering apparatus and sintering method for porous glass base material - Google Patents

Description

The present invention relates to a sintering device and a sintering method for a porous glass preform.

A sintering device for sintering a porous glass base material is known (for example, Patent Documents 1 and 2).

JP-A-63-159232 JP, 2002-068770, A

The porous glass preform sintering apparatus disclosed in Patent Documents 1 and 2 discharges exhaust gas through an exhaust pipe. This exhaust pipe is connected to an exhaust gas treatment device such as a scrubber. Usually, the exhaust gas treatment device is provided with a fan for invitation, and the fan for invitation is used to generate exhaust pressure to exhaust the exhaust gas through the exhaust pipe. However, it is difficult to make the pulling pressure constant because the pressure fluctuation occurs when the fan of the quotation is used. For this reason, the pressure difference between the inside and outside of the furnace core tube in the sintering device may fluctuate, and gas may leak from the gap between the furnace core tubes.

It is an object of the present invention to provide a porous glass preform sintering apparatus and a sintering method capable of reducing the fluctuation of the exhaust pressure of the exhaust pipe.

A porous glass preform sintering apparatus according to an aspect of the present invention,
A core tube arranged in the furnace body for accommodating the porous glass base material and performing sintering;
A supply port for supplying gas into the core tube,
An exhaust port for exhausting gas from the core tube,
The exhaust port is connected to an exhaust gas treatment device via an exhaust pipe,
An ejector provided in the middle of the exhaust pipe so as to generate a drawing pressure from the exhaust port to the exhaust gas treatment device, and a flow rate adjustment for adjusting a flow rate of a gas connected to the ejector to generate the drawing pressure. And a container.

Further, the method for sintering a porous glass preform according to an aspect of the present invention,
An exhaust pipe for exhausting gas from the core tube, the core tube arranged in the furnace body, a supply port for supplying gas into the core tube, and an exhaust port for exhausting gas from the core tube. Using a sintering device connected to the exhaust gas treatment device via, a method of sintering a porous glass preform for accommodating and sintering the porous preform in the furnace tube,
An ejector is arranged in the middle of the exhaust pipe so as to generate a drawing pressure from the exhaust port to the exhaust gas processing device, and the flow rate of the gas for generating the drawing pressure in the ejector is adjusted to adjust the inside of the core tube. The porous glass base material is sintered while maintaining the pressure of 1 to a predetermined pressure.

According to the above invention, it is possible to reduce fluctuations in the exhaust pressure of the exhaust pipe.

It is the schematic which shows an example of the sintering apparatus of the porous glass base material which concerns on this embodiment. It is a figure for explaining a sintering furnace of a sintering device.

(Description of Embodiments of the Present Invention)
First, embodiments of the present invention will be listed and described.
A porous glass preform sintering apparatus according to an aspect of the present invention,
(1) A core tube arranged in a furnace body for containing a porous glass base material and performing sintering,
A supply port for supplying gas into the core tube,
An exhaust port for exhausting gas from the core tube,
The exhaust port is connected to an exhaust gas treatment device via an exhaust pipe,
An ejector provided in the middle of the exhaust pipe so as to generate a drawing pressure from the exhaust port to the exhaust gas treatment device, and a flow rate adjustment for adjusting a flow rate of a gas connected to the ejector to generate the drawing pressure. And a container.
According to the above configuration, since the ejector is provided in the middle of the exhaust pipe so as to generate the suction pressure from the exhaust port to the exhaust gas treatment device, it is possible to reduce fluctuations in the exhaust pressure of the exhaust pipe. This stabilizes the pressure difference between the inside and the outside of the furnace tube in the sintering device, so that gas leakage from the gap in the tube can be suppressed. Further, since it is not necessary to provide a regulating valve for regulating the pulling pressure in the exhaust pipe, there is no problem that the regulating valve is clogged with the solid matter contained in the exhaust gas.

(2) a pressure measuring unit for measuring the pressure in the core tube,
Based on the measurement result of the pressure measuring unit, the flow rate of the gas is adjusted by the flow rate adjuster to generate a predetermined pulling pressure from the exhaust port to the exhaust gas treatment device to set a predetermined pressure in the core tube. Control unit to maintain the pressure of
Is preferably provided.
By adjusting the flow rate of the gas by the flow rate regulator based on the measurement result of the pressure measurement unit, it is possible to generate a predetermined pulling pressure from the exhaust port to the exhaust gas treatment device, and to set the pressure in the core tube to the predetermined pressure. Can be maintained.

(3) The core tube is
The first core tube,
A second core tube arranged in the first core tube,
An intermediate chamber is defined between the first core tube and the second core tube,
The exhaust port is provided in the intermediate chamber,
The pressure measuring unit measures the pressure of the intermediate chamber,
The control unit adjusts the flow rate of the gas by the flow rate regulator based on the measurement result of the pressure in the intermediate chamber measured by the pressure measuring unit, and maintains the pressure in the intermediate chamber at a predetermined pressure. Preferably.
The core tube comprises a first core tube and a second core tube arranged in the first core tube, an intermediate chamber is defined between the first core tube and the second core tube, and the exhaust port is In the sintering device provided in the intermediate chamber, the flow rate of the gas for generating the pulling pressure in the ejector is adjusted based on the measurement result of the pressure in the intermediate chamber to maintain the pressure in the intermediate chamber at a predetermined pressure. However, by sintering the porous glass base material, it is possible to reduce fluctuations in the exhaust pressure of the exhaust pipe.

Further, the method for sintering a porous glass preform according to an aspect of the present invention,
(4) Exhaust port for exhausting gas from the inside of the core tube, which includes a core tube arranged in the core, a supply port for supplying gas into the core tube, and an exhaust port for exhausting gas from the core tube Using a sintering device connected to an exhaust gas treatment device via an exhaust pipe, a method of sintering a porous glass preform for accommodating and sintering the porous preform in the core tube,
An ejector is arranged in the middle of the exhaust pipe so as to generate a drawing pressure from the exhaust port to the exhaust gas processing device, and the flow rate of the gas for generating the drawing pressure in the ejector is adjusted to adjust the inside of the core tube. The porous glass base material is sintered while maintaining the pressure of 1 to a predetermined pressure.
According to the above method, a core tube arranged in the furnace body, a supply port for supplying gas into the core tube, and an exhaust port for exhausting gas from the core tube, and an exhaust port for exhausting gas from the core tube Using a sintering device connected to the exhaust gas treatment device via the exhaust pipe, when the porous base material is housed in the core tube for sintering, an ejector is arranged in the middle of the exhaust pipe. By generating a suction pressure from the exhaust port to the exhaust gas treatment device, fluctuations in the suction pressure of the exhaust gas in the exhaust pipe can be reduced. This stabilizes the pressure difference between the inside and the outside of the furnace tube in the sintering device, so that gas leakage from the gap in the tube can be suppressed. Further, since it is not necessary to provide a regulating valve for regulating the pulling pressure in the exhaust pipe, there is no problem that the regulating valve is clogged with the solid matter contained in the exhaust gas.

(5) The core tube is composed of a first core tube and a second core tube arranged in the first core tube, and an intermediate chamber is defined between the first core tube and the second core tube. And, using the sintering device in which the exhaust port is provided in the intermediate chamber,
The pressure in the intermediate chamber is measured, and based on the measured result of the pressure in the intermediate chamber, while maintaining the pressure in the intermediate chamber at a predetermined pressure by adjusting the flow rate of the gas, the porous It is preferred to sinter the glass matrix.
The core tube comprises a first core tube and a second core tube arranged in the first core tube, an intermediate chamber is defined between the first core tube and the second core tube, and the exhaust port is In the sintering device provided in the intermediate chamber, the flow rate of the gas for generating the pulling pressure in the ejector is adjusted based on the measurement result of the pressure in the intermediate chamber to maintain the pressure in the intermediate chamber at a predetermined pressure. However, by sintering the porous glass base material, it is possible to reduce fluctuations in the exhaust pressure of the exhaust pipe.

(Details of the embodiment of the present invention)
Specific examples of the apparatus and method for sintering a porous glass preform according to the embodiment of the present invention will be described below with reference to the drawings.
It should be noted that the present invention is not limited to these exemplifications, and is shown by the scope of the claims, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope.

FIG. 1 is a diagram showing an example of an apparatus for sintering a porous glass preform.
As shown in FIG. 1, the sintering device 100 is provided in the middle of a sintering furnace 30, an exhaust gas treatment device 70, and a gas exhaust pipe 14 that is piped from the sintering furnace 30 to the exhaust gas treatment device 70. The ejector 50 is provided.
The sintering furnace 30 is a furnace for dehydrating and sintering the glass particle deposit body (porous glass base material) 1 on which glass particles are deposited. The exhaust gas treatment device 70 is a device that treats the exhaust gas from the sintering furnace 30 and has an exhaust gas treatment function such as a scrubber. The ejector 50 is a device that generates a drawing pressure from the sintering furnace 30 to the exhaust gas processing device 70.

FIG. 2 is a diagram showing a detailed configuration of the sintering furnace 30.
As shown in FIG. 2, in the sintering furnace 30, the first furnace core tube 3 is arranged in the furnace body 7, and the second furnace core tube 4 is coaxial with the first furnace core tube 3 in the first furnace core tube 3. It is arranged and configured. A space (hereinafter referred to as an intermediate chamber) 10 is defined between the first core tube 3 and the second core tube 4.

The porous glass preform 1 made of SiO ₂ particles has a support rod 2 as a starting rod, which is formed on the penetration portion 4a of the second furnace core tube 4, the penetration portion 3a of the first furnace core tube 3 and the penetration portion 7a of the furnace body 7. It is suspended and supported at the center of the second furnace tube 4. Each of the first furnace core tube 3 and the second furnace core tube 4 is formed by dividing a cylindrical side wall member made of high-purity carbon into a plurality of parts and stacking them in multiple stages, and the upper and lower parts thereof are a disc-shaped lid and a bottom part. It is configured by being sealed with a material. The joint portion between the side wall members in the first furnace core tube 3 is referred to as a joint portion 3b, and the joint portion between the side wall members in the second reactor tube 4 is referred to as a joint portion 4b. The first furnace core tube 3 and the second furnace core tube 4 may have a split structure of quartz, for example.

A heater 5 is arranged outside the first core tube 3. A heat insulating material 6 is arranged outside the heater 5 to block the heat of the heater 5 from being dissipated to the outside. The furnace body 7 is formed of a metal having excellent corrosion resistance such as stainless steel, and surrounds the entire components including the first furnace core tube 3 and the second furnace core tube 4 and completely seals it from the outer atmosphere.

A gas supply pipe 11 for supplying a gas for dehydration treatment and sintering treatment of the porous glass base material 1 (hereinafter referred to as a dehydration/sintering gas) to the second furnace core pipe 4, and a second reactor core pipe 4 The gas exhaust pipes 12 for exhausting the gas therein are independently connected. A gas supply pipe 13 to which an inert gas is supplied is connected to the supply port 10a of the intermediate chamber 10. A gas exhaust pipe 14 that exhausts the gas in the intermediate chamber 10 is connected to the exhaust port 10b of the intermediate chamber 10. A gas supply pipe 15 for supplying an inert gas and a gas exhaust pipe 16 for exhausting the gas inside the furnace body are independently connected to the furnace body 7.

A space (hereinafter, referred to as a core chamber) 8 in the second furnace tube 4 is supplied from a gas supply tube 11 as a gas for dehydration and sintering of the porous glass base material 1, for example, helium gas which is advantageous for making glass transparent. A mixed gas of chlorine gas, which is advantageous for dehydration treatment, is supplied. Further, the dehydration-sintering gas includes a corrosive gas such as SiCl ₄ or SiF ₄ . A fluorine compound gas that decomposes at high temperature may be supplied to adjust the refractive index of the porous glass base material 1. The supply gas is not particularly limited to this example, and different kinds of gas are used depending on the manufacturing process of the porous glass base material 1.

The moisture released from the porous glass base material 1 hydrolyzes with a part of the supply gas to generate a corrosive gas such as hydrogen chloride or hydrogen fluoride. Further, the generated gas contains dust particles such as silica fine particles. These gases are exhausted to the gas exhaust pipe 12 and processed by the exhaust gas processing device 70.

A space (hereinafter, referred to as a furnace body chamber) 9 between the furnace body 7 and the first furnace core tube 3 is filled with a gas such as nitrogen or argon gas so that the heater 5 and the heat insulating material 6 do not deteriorate due to oxidation. The inert gas is supplied from the gas supply pipe 15. These gases are exhausted to the gas exhaust pipe 16 and processed by the exhaust gas processing device 70.

An inert gas such as helium gas is supplied from a gas supply pipe 13 to the intermediate chamber 10 between the first furnace core tube 3 and the second furnace core tube 4. These gases are exhausted to the gas exhaust pipe 14 and processed by the exhaust gas processing device 70. The intermediate chamber 10 shuts off the core chamber 8 of the second core tube 4 and the furnace chamber 9 which is the space of the furnace body 7.

As shown in FIG. 1, a pressure gauge 21 (an example of a pressure measuring unit) for measuring the pressure in the intermediate chamber 10 is connected to the gas supply pipe 13 of the sintering furnace 30. The pressure gauge 21 is connected to a gas pressure control unit 29 (an example of a control unit), and the pressure value in the intermediate chamber 10 measured by the pressure gauge 21 is sent to the gas pressure control unit 29.

The exhaust gas treatment device 70 is provided with, for example, an induction fan that generates an air flow that attracts the exhaust gas into the exhaust gas treatment device 70 with respect to each of the gas exhaust pipes 12, 14, 16. However, since the induction fan generates an airflow that is attracted by, for example, the rotation of the rotary blades, pressure variation occurs in the attraction pressure that is attracted, and it is difficult to keep the attraction pressure constant. As described above, when the pressure variation of the drawing pressure with respect to each of the gas exhaust pipes 12, 14, 16 occurs, the pressure difference between the inside and outside of the furnace core tube in the sintering apparatus 100 fluctuates, and gas leakage may occur from the gap of the furnace core tube. there were.

Therefore, the present inventors connect a vacuum pump to the gas exhaust pipe of the intermediate chamber and adjust the suction pressure of the vacuum pump to the exhaust pipe in order to control the pressure in the intermediate chamber, which requires particularly fine pressure adjustment. I thought of installing a regulating valve to do this. However, since the gas flow path in the exhaust pipe becomes narrower at the position of the adjusting valve, it is known that the solid matter contained in the exhaust gas is likely to be clogged, and the adjusting valve is blocked and the pulling pressure is weakened. It was

In consideration of the above, in the sintering apparatus 100 of the present embodiment, the gas exhaust pipe 14 is provided with the ejector 50 that uses gas to create a reduced pressure state by the Venturi effect. A supply pipe 54 is connected to the supply port 51 of the ejector 50, and a gas such as nitrogen or air is supplied to the supply port 51, that is, the ejector 50 via the supply pipe 54. The supply pipe 54 is provided with a mass flow controller (mass flow controller: MFC, an example of a flow rate controller) 55 that adjusts the flow rate of the gas supplied to the supply port 51. The MFC 55 is connected to the gas pressure control unit 29.

The gas pressure control unit 29 compares the actually measured pressure value in the intermediate chamber 10 measured by the pressure gauge 21 with a preset pressure value set as the pressure in the intermediate chamber 10, and based on the comparison result, the ejector 50. To control. For example, when the measured pressure value is lower than the set pressure value, the gas pressure control unit 29 sends a flow rate control signal for reducing the flow rate of the gas supplied to the supply port 51 to the MFC 55. When the measured pressure value is higher than the set pressure value, the gas pressure control unit 29 sends a flow rate control signal to the MFC 55 to increase the flow rate of the gas supplied to the supply port 51. The MFC 55 adjusts the flow rate of gas based on the control signal sent from the gas pressure control unit 29.

The gas supplied to the supply port 51 becomes a high-speed gas flow, is injected into the ejector 50, and advances toward the exhaust port 52 of the ejector 50. A negative static pressure is generated by this gas flow, and the inside of the ejector 50 is in a reduced pressure state. When the pressure inside the ejector 50 is reduced, a pulling pressure is generated in the gas exhaust pipe 14 connected to the intake port 53 of the ejector 50 from the intermediate chamber 10 toward the exhaust gas treatment device 70, and is exhausted from the intermediate chamber 10. Exhaust gas is drawn into the intake port 53 via the gas exhaust pipe 14.

The high-speed gas injected from the supply port 51 and the exhaust gas sucked from the intake port 53 are discharged from the exhaust port 52 to the outside of the ejector 50. The exhaust gas discharged from the ejector 50 is discharged to the exhaust gas processing device 70 through the gas exhaust pipe 14 connected to the exhaust port 52.

When the flow rate of the gas supplied into the ejector 50 decreases, the flow of the gas injected into the ejector 50 becomes weak, and the decompression amount in the ejector 50 decreases. When the amount of reduced pressure becomes small, the force of drawing the exhaust gas from the gas exhaust pipe 14 of the intermediate chamber 10 to the drawing port 53 of the ejector 50 becomes weak, and the drawing pressure from the intermediate chamber 10 to the exhaust gas treatment device 70 becomes small. As a result, the pressure in the intermediate chamber 10 rises. On the contrary, when the flow rate of the gas supplied into the ejector 50 becomes large, the flow of the gas injected into the ejector 50 becomes strong and the decompression amount inside the ejector 50 becomes large. When the amount of decompression increases, the drawing force for drawing the exhaust gas from the gas exhaust pipe 14 of the intermediate chamber 10 to the drawing port 53 of the ejector 50 becomes strong, and the drawing pressure from the intermediate chamber 10 to the exhaust gas treatment device 70 becomes large. Therefore, the pressure in the intermediate chamber 10 decreases. In this way, by adjusting the flow rate of the gas by the MFC 55, the drawing pressure from the intermediate chamber 10 to the exhaust gas treatment device 70 is controlled, and the pressure in the intermediate chamber 10 is maintained within a predetermined range.

Further, the gas supply pipe 13 is provided with an openable/closable supply valve 22 that can shut off the supply of gas to the intermediate chamber 10. The gas exhaust pipe 14 is provided with exhaust valves 23 and 24 capable of blocking the exhaust of gas from the intermediate chamber 10. Although not shown, the supply valve 22 and the exhaust valve 23 are connected to a gas pressure control unit 29, respectively, and under the control of the gas pressure control unit 29, an open state that allows gas to pass through during operation of the sintering apparatus 100. In addition, it is adjusted to a closed state that shuts off gas when not in operation.

A pressure gauge 31 for measuring the pressure in the core chamber 8 is connected to the gas supply pipe 11 of the sintering furnace 30. Further, the gas supply pipe 11 is provided with an openable/closable supply valve 32 capable of shutting off the supply of gas to the core chamber 8, and the gas exhaust pipe 12 is exhausted to shut off the discharge of gas from the core chamber 8. The valve 33 is provided. The pressure gauge 31, the supply valve 32, and the exhaust valve 33 are connected to the gas pressure control unit 29, though not shown. The pressure value in the core chamber 8 measured by the pressure gauge 31 is sent to the gas pressure control unit 29. The supply valve 32 and the exhaust valve 33 are controlled in the same manner as the supply valve 22 and the exhaust valve 23.

A pressure gauge 34 for measuring the pressure inside the furnace body chamber 9 is connected to the gas supply pipe 15 of the sintering furnace 30. Further, the gas supply pipe 15 is provided with an openable/closable supply valve 35 capable of shutting off the supply of gas to the furnace body chamber 9, and the gas exhaust pipe 16 is shut off from the discharge of gas from the furnace body chamber 9. An exhaust valve 36 is provided. The pressure gauge 34, the supply valve 35, and the exhaust valve 36 are connected to the gas pressure control unit 29, though not shown. The pressure value in the furnace chamber 9 measured by the pressure gauge 34 is sent to the gas pressure control unit 29. The supply valve 35 and the exhaust valve 36 are controlled similarly to the supply valve 22 and the exhaust valve 23.

The pressure in the intermediate chamber 10 is adjusted by the MFC 55 connected to the ejector 50 so as to be a pressure slightly lower than the pressures in the core chamber 8 and the furnace body chamber 9.
When the pressure in the intermediate chamber 10 is set to be slightly lower than the pressure in the core chamber 8, the gas in the core chamber 8 leaks to the intermediate chamber 10 from the penetration portion 4a and the joint portion 4b, which have insufficient airtightness. There are cases. However, the gas leaking into the intermediate chamber 10 is discharged to the outside of the sintering furnace 30 through the gas exhaust pipe 14, and does not leak to the core chamber 8 on the high pressure side. Further, when the pressure of the intermediate chamber 10 is set to be slightly lower than the pressure of the furnace chamber 9, the gas in the furnace chamber 9 flows from the through portion 3a and the joint portion 3b of the first furnace core tube 3 to the intermediate chamber 10 There may be some leakage inside. However, the gas leaking to the intermediate chamber 10 is discharged to the outside of the sintering furnace 30 through the gas exhaust pipe 14, and does not leak to the furnace body chamber 9 on the high pressure side.

That is, the corrosive gas generated in the second furnace core tube 4 may leak into the intermediate chamber 10 but not into the furnace body chamber 9 of the furnace body 7. Similarly, the gas containing impurities generated from the heat insulating material 6 and the metal of the furnace body 7 may leak into the intermediate chamber 10 but not into the reactor core chamber 8 of the second furnace core tube 4. Absent. In this way, the first core tube 3 and the second core tube 4 serving as partition walls for separating the gas in the core chamber 8 and the gas in the furnace chamber 9 from each other, the joint portion 3b having insufficient airtightness, Even if 4b and the penetrating portions 3a and 4a are present, the separated gases are prevented from leaking into the mutual chambers.

The pressure difference between the intermediate chamber 10 and the core chamber 8 and the furnace body chamber 9 is such a small pressure difference that can prevent gas from flowing from the intermediate chamber 10 to the core chamber 8 and from the intermediate chamber 10 to the furnace body chamber 9. Should exist. Specifically, the pressure P in the intermediate chamber 10 is set to 101.3 to 102.3 KPa (atmospheric pressure is 101.325 KPa), and the pressure in the core chamber 8 is P+(0.01 to 0.2) KPa, The pressure in the furnace chamber 9 is in the range of P+(0.1 to 1.0) KPa.

In addition, in the above-mentioned embodiment, the sintering apparatus of the double core tube provided with double core tubes (the first core tube 3 and the second core tube 4) in the furnace body 7 has been described. It may be a single-core tube sintering apparatus including only the core tube (2nd core tube of the above embodiment). In this case, the ejector 50 is attached to the discharge path of the single core tube, that is, an exhaust pipe connected between the core tube and the exhaust gas treatment device.

As described above, according to the configuration of the present embodiment, the ejector 50 is provided in the middle of the gas exhaust pipe 14 connected between the intermediate chamber 10 and the exhaust gas treatment device 70, and is supplied to the ejector 50. An MFC 55 that adjusts the flow rate of gas is provided. Therefore, the suction pressure can be generated from the intermediate chamber 10 toward the exhaust gas treatment device 70, and the generated suction pressure is controlled by the MFC 55 to reduce the fluctuation of the suction pressure of the exhaust gas in the gas exhaust pipe 14. You can This stabilizes the pressure difference between the inside and outside of the furnace tube in the sintering machine 100.

If the gas exhaust pipe is equipped with an adjusting valve for adjusting the exhaust pressure, dust particles contained in the exhaust gas will easily adhere to the adjusting valve and become clogged. There is a case where a pressure reversal phenomenon occurs. However, according to the configuration of the present embodiment, since the gas exhaust pipe 14 is not provided with a regulating valve or the like, the pressure reversal between the intermediate chamber 10, the core chamber 8 and the furnace body chamber 9 due to clogging of the gas exhaust pipe 14. The phenomenon cannot occur. Therefore, the gas leaking from the core chamber 8 into the intermediate chamber 10 does not leak into the furnace body chamber 9, and the gas leaking from the furnace chamber 9 into the intermediate chamber 10 does not leak into the core chamber 8. No defects such as product defects or equipment troubles will occur.

The gas flow rate is adjusted by the MFC 55 under the control of the gas pressure control unit 29 based on the measurement result of the pressure gauge 21. Therefore, the suction pressure from the intermediate chamber 10 to the exhaust gas treatment device 70 can be accurately generated, the fluctuation of the suction pressure can be further reduced, and the pressure in the intermediate chamber 10 is maintained at a predetermined pressure. be able to.

While the present invention has been described in detail and with reference to particular embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. Further, the number, position, shape, etc. of the constituent members described above are not limited to those in the above-described embodiment, and can be changed to the number, position, shape, etc. suitable for implementing the present invention.

1 Porous Glass Base Material 2 Support Rod 3 First Reactor Tube 4 Second Reactor Tube 5 Heater 6 Heat Insulating Material 7 Reactor Body 8 Reactor Core Room 9 Reactor Body Room 10 Intermediate Room 10a Supply Port 10b Exhaust Ports 11, 13, 15 Gas Supply pipes 12, 14, 16 Gas exhaust pipe 21 Pressure gauge (an example of pressure measuring unit)
29 Gas pressure control unit (an example of control unit)
30 Sintering furnace 50 Ejector 51 Supply port 52 Exhaust port 53 Inlet port 54 Supply pipe 55 Mass flow controller (an example of a flow controller)
70 Exhaust gas treatment device 100 Sintering device

Claims (2)

A core tube arranged in the furnace body for accommodating the porous glass base material and performing sintering;
A supply port for supplying gas into the core tube,
An exhaust port connected to an exhaust gas treatment device through an exhaust pipe for exhausting gas from the core tube,
An ejector provided in the middle of the exhaust pipe so as to generate a drawing pressure from the exhaust port to the exhaust gas treatment device,
A flow rate controller connected to the ejector for adjusting the flow rate of the gas for generating the pulling pressure;
A pressure measuring unit for measuring the pressure in the core tube,
Based on the measurement result of the pressure measuring unit, the flow rate of the gas is adjusted by the flow rate adjuster to generate a predetermined pulling pressure from the exhaust port to the exhaust gas treatment device to set a predetermined pressure in the core tube. Control unit to maintain the pressure of
Equipped with
The exhaust pipe is not provided with a control valve for adjusting the pulling pressure,
The core tube is
The first core tube,
A second core tube arranged in the first core tube,
An intermediate chamber is defined between the first core tube and the second core tube,
The exhaust port is provided in the intermediate chamber,
The pressure measuring unit measures the pressure of the intermediate chamber,
The control unit adjusts the flow rate of the gas by the flow rate regulator based on the measurement result of the pressure in the intermediate chamber measured by the pressure measuring unit, and maintains the pressure in the intermediate chamber at a predetermined pressure. To do
Sintering device for porous glass base material. A core tube arranged in the furnace body; a supply port for supplying gas into the core tube; and an exhaust port connected to an exhaust gas treatment device via an exhaust pipe for exhausting gas from the core tube. The core tube is constituted by a first core tube and a second core tube arranged in the first core tube, and an intermediate chamber is defined between the first core tube and the second core tube. A sintering method of a porous glass preform for accommodating and sintering a porous preform in the furnace core tube, using a sintering device in which the exhaust port is provided in the intermediate chamber,
Without providing an adjusting valve for adjusting the drawing pressure in the exhaust pipe, an ejector is arranged in the middle of the exhaust pipe so as to generate a drawing pressure from the exhaust port to the exhaust gas treatment device,
The pressure in the intermediate chamber is measured, and based on the measured result of the pressure in the intermediate chamber, the flow rate of the gas for causing the ejector to generate the pulling pressure is adjusted to set the pressure in the intermediate chamber to a predetermined value. A method for sintering a porous glass base material, comprising sintering the porous glass base material while maintaining the pressure.

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