Manufacturing method and manufacturing apparatus for glass particulate deposit body

Abstract

To improve accuracy in the flow rate measurement of liquid siloxane to appropriately control the supply amount of the fluid siloxane.SOLUTION: A method for manufacturing a glass particle deposit comprises the steps of: supplying liquid siloxane to a vaporizer through a supply pipe; measuring the flow rate of the liquid siloxane in the supply pipe by a first flowmeter to control the supply amount of the liquid siloxane supplied to the vaporizer on the basis of the measurement results by the first flowmeter; and sending siloxane gas vaporized by the vaporizer to a burner to oxidize the siloxane gas and deposit glass fine particles. The step of controlling the supply amount of the liquid siloxane comprises further controlling the supply amount on the basis of measurement results by a second flowmeter for measuring the flow rate by a measurement principle different from that of the first flowmeter.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method and an apparatus for manufacturing a soot glass deposit body. [Background technology]

[0002] Patent Document 1 discloses an apparatus for manufacturing a glass soot deposit body using siloxane as a raw material. Specifically, Patent Document 1 discloses that liquid siloxane is sent to a vaporizer, vaporized by the vaporizer, and the resulting siloxane gas is supplied to a burner. Patent Document 1 also discloses that the flow rate of the liquid siloxane supplied to the vaporizer is controlled using an MFC (Mass Flow Controller). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 116523 Summary of the Invention [Problem to be solved by the invention]

[0004] When silicon tetrachloride is used as a raw material for the glass soot deposit body, a high-temperature MFC can be used to control the amount of silicon tetrachloride gas supplied to the burner. However, because siloxane has a higher boiling point than silicon tetrachloride, it is difficult to directly measure the flow rate of the siloxane gas. Therefore, as in Patent Document 1, the flow rate of liquid siloxane before vaporization is measured and controlled to relatively control the amount of siloxane gas supplied to the burner.

[0005] Conventionally, thermal or differential pressure flow meters have been used to measure the flow rate of liquid siloxane, but these flow meters can produce unstable measurement results due to the influence of temperature transmitted from the vaporizer and bubbles generated by dissolved gas due to pressure loss.

[0006] An object of the present disclosure is to improve the accuracy in measuring the flow rate of liquid siloxane and to appropriately control the supply amount of liquid siloxane. [Means for solving the problem]

[0007] A method for producing a soot glass deposit body according to one embodiment of the present disclosure includes: supplying liquid siloxane to a vaporizer via a supply line; measuring the flow rate of the liquid siloxane in the supply pipe with a first flow meter, and controlling the supply amount of the liquid siloxane supplied to the vaporizer based on the measurement result of the first flow meter; a step of supplying the siloxane gas vaporized by the vaporizer to a burner, and causing an oxidation reaction of the siloxane gas to deposit glass particles; The controlling step includes further controlling the supply amount based on a measurement result from a second flow meter that measures the flow rate using a measurement principle different from that of the first flow meter.

[0008] An apparatus for manufacturing a soot glass deposit body according to one aspect of the present disclosure includes: a supply line for supplying liquid siloxane to the vaporizer; a vaporizer for vaporizing the liquid siloxane; a first flow meter that measures the flow rate of the liquid siloxane in the supply pipe; a control unit that controls the amount of the liquid siloxane supplied to the vaporizer based on the measurement result of the first flow meter; a burner that causes an oxidation reaction of the siloxane gas vaporized by the vaporizer to deposit glass particles; a second flow meter that measures the flow rate using a measurement principle different from that of the first flow meter; The control unit No. 2 The supply amount is further controlled based on the measurement results from the flow meter. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to improve the accuracy in measuring the flow rate of liquid siloxane and appropriately control the supply amount of liquid siloxane. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram schematically illustrating a soot glass deposit manufacturing apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram schematically illustrating the configuration of the vaporizing unit shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. A method for producing a soot glass deposit body according to one embodiment of the present disclosure includes: supplying liquid siloxane to a vaporizer via a supply line; measuring the flow rate of the liquid siloxane in the supply pipe with a first flow meter, and controlling the supply amount of the liquid siloxane supplied to the vaporizer based on the measurement result of the first flow meter; a step of supplying the siloxane gas vaporized by the vaporizer to a burner, and causing an oxidation reaction of the siloxane gas to deposit glass particles; The controlling step includes further controlling the supply amount based on a measurement result from a second flow meter that measures the flow rate using a measurement principle different from that of the first flow meter.

[0012] This configuration improves the accuracy of measuring the flow rate of the liquid siloxane, and makes it possible to appropriately control the supply amount of the liquid siloxane. Specifically, by using two types of flow meters, a first flow meter and a second flow meter that uses a different measurement principle than the first flow meter, even if the measurement results of the first flow meter become unstable due to factors such as temperature changes, it is possible to control the supply amount of liquid siloxane based on the measurement results of the second flow meter, or to correct the measurement results of the first flow meter using the measurement results of the second flow meter. As a result, the accuracy of liquid siloxane flow rate measurement is improved, and the supply amount of liquid siloxane can be appropriately controlled.

[0013] In the method for producing a soot glass deposit body, the first flow meter is a thermal or differential pressure flow meter, The second flow meter is preferably an ultrasonic or Coriolis flow meter.

[0014] The ultrasonic flow meter is capable of measuring the flow rate of liquid siloxane without being affected by the temperature from the vaporizer, and therefore, with the above configuration, the temperature dependency in measuring the flow rate of liquid siloxane can be reduced. Furthermore, the ultrasonic flowmeter can detect any air bubbles or foreign matter that may be present in the liquid siloxane, and therefore, with the above configuration, control can be implemented based on the detection of air bubbles or foreign matter.

[0015] The method for producing the glass soot deposit body includes the steps of: In the supply pipe, a measurement position by the first flow meter is located closer to the vaporizer than a measurement position by the second flow meter, the second flow meter has a function of detecting air bubbles or foreign matter in the supply pipe, If the second flow meter detects air bubbles or foreign matter in the supply pipe, it is preferable to determine that the measurement result by the first flow meter is an abnormal value within a predetermined period after the air bubbles or foreign matter are detected.

[0016] With this configuration, the second flow meter can detect the presence of air bubbles or foreign matter in the liquid siloxane before the first flow meter does, and in that case, by determining that the measurement value of the first flow meter is an abnormal value, it is possible to prevent a situation in which the supply amount of liquid siloxane is controlled based on the abnormal measurement value.

[0017] The method for producing the glass soot deposit body includes the steps of: In the supply pipe, a measurement position by the first flow meter is located closer to the vaporizer than a measurement position by the second flow meter, The distance between the measurement position of the first flow meter and the measurement position of the second flow meter is preferably 10 mm or more and 500 mm or less.

[0018] According to this configuration, by appropriately setting the measurement positions of the second flow meter and the first flow meter, the measurement results of the first flow meter can be corrected more appropriately based on the measurement results of the second flow meter.

[0019] An apparatus for manufacturing a soot glass deposit body according to one aspect of the present disclosure includes: a supply line for supplying liquid siloxane to the vaporizer; a vaporizer for vaporizing the liquid siloxane; a first flow meter that measures the flow rate of the liquid siloxane in the supply pipe; a control unit that controls the amount of the liquid siloxane supplied to the vaporizer based on the measurement result of the first flow meter; a burner that causes an oxidation reaction of the siloxane gas vaporized by the vaporizer to deposit glass particles; a second flow meter that measures the flow rate using a measurement principle different from that of the first flow meter; The control unit No. 2 The supply amount is further controlled based on the measurement results from the flow meter.

[0020] This configuration improves the accuracy of measuring the flow rate of the liquid siloxane, and makes it possible to appropriately control the supply amount of the liquid siloxane. Specifically, by using two types of flow meters, a first flow meter and a second flow meter that uses a different measurement principle than the first flow meter, even if the measurement results of the first flow meter become unstable due to factors such as temperature changes, it is possible to control the supply amount of liquid siloxane based on the measurement results of the second flow meter, or to correct the measurement results of the first flow meter using the measurement results of the second flow meter. As a result, the accuracy of liquid siloxane flow rate measurement is improved, and the supply amount of liquid siloxane can be appropriately controlled.

[0021] [Details of the embodiments of the present disclosure] Hereinafter, examples of embodiments of a soot glass deposit manufacturing apparatus and a soot glass deposit manufacturing method according to the present disclosure will be described with reference to the drawings. For the sake of convenience, the dimensions of each component shown in each drawing may differ from the actual dimensions of each component.

[0022] (Glass particle deposit manufacturing equipment) First, a soot glass deposit manufacturing apparatus 1 according to an embodiment of the present disclosure will be described with reference to Figures 1 and 2. Figure 1 is a diagram schematically illustrating the soot glass deposit manufacturing apparatus 1. The manufacturing apparatus 1 includes a reaction vessel 2, an elevation and rotation device 3, a vaporization section 20, a raw material vessel 30, a burner 34 for generating glass soot, and a control section 4 that controls the operation of each section.

[0023] The reaction vessel 2 is a vessel in which the glass soot deposit M is formed. An exhaust pipe 12 is attached to the side of the reaction vessel 2. The lifting and rotating device 3 is a device that lifts and rotates the glass soot deposit M via a support rod 10 and a starting rod 11. The lifting and rotating device 3 controls the operation of the support rod 10 based on a control signal sent from a control unit 4. The lifting and rotating device 3 lifts and lowers the glass soot deposit M while rotating it.

[0024] The support rod 10 is disposed by passing through a through-hole formed in the upper wall of the reaction vessel 2, and a starting rod 11 is attached to one end (the lower end in FIG. 1) that is disposed inside the reaction vessel 2. The other end (the upper end in FIG. 1) of the support rod 10 is held by the lifting and rotating device 3. The starting rod 11 is a rod on which glass particles are deposited, and is attached to the support rod 10. The exhaust pipe 12 is a pipe that exhausts glass particles 35 that have not adhered to the starting rod 11 and the glass particle deposit M to the outside of the reaction vessel 2 together with the gas inside the reaction vessel 2.

[0025] Liquid siloxane 31 is stored as a raw material in a raw material container 30. Examples of siloxane that can be used include octamethylcyclotetrasiloxane (OMCTS), decamethylcyclopentasiloxane (DMCPS), hexamethylcyclotrisiloxane, and hexamethyldisiloxane. In this example, a case where OMCTS is used as the siloxane will be described.

[0026] Liquid siloxane 31 in a raw material container 30 is supplied to the vaporizer 20 via a supply pipe 32. The vaporizer 20 will be described in detail later with reference to FIG. 2. The liquid siloxane 31 is vaporized in the vaporizer 20 to form siloxane gas. The siloxane gas is supplied to a burner 34 via a temperature control pipe 33. The temperature control pipe 33 maintains a high temperature within the pipe so that the siloxane gas does not liquefy. The temperature control pipe 33 is, for example, a pipe wrapped around a tape heater, which is a heating element.

[0027] The burner 34 is supplied with the siloxane gas vaporized in the vaporization section 20 and a flame-forming gas. The flame-forming gas is, for example, hydrogen gas and oxygen gas. An inert gas such as nitrogen gas or argon gas may also be supplied to the burner 34 as a seal gas. Note that a supply device that supplies the flame-forming gas to the burner 34 and a supply device that supplies the seal gas to the burner 34 are not shown in FIG. The burner 34 generates glass microparticles 35 by oxidizing the siloxane gas in the flame, and the generated glass microparticles 35 are sprayed onto the starting rod 11 to deposit them.

[0028] The control unit 4 controls each operation of the lifting and rotating device 3. The control unit 4 transmits a control signal to the lifting and rotating device 3 to control the lifting speed and rotation speed of the soot glass deposit body M. The control unit 4 may also control each operation of at least some of the devices included in the vaporizing unit 20, such as the control unit 26 (see FIG. 2).

[0029] Here, vaporization unit 20 will be described in detail. Fig. 2 is a diagram schematically showing the configuration of vaporization unit 20 shown in Fig. 1. As shown in Fig. 2, vaporization unit 20 includes first flow meter 22, second flow meter 21, mixer 23, vaporizer 24, MFC 25, and control unit 26.

[0030] The first flow meter 22 measures the flow rate of the liquid siloxane 31 in the supply pipe 32. The amount of the liquid siloxane 31 supplied to the vaporizer 24 is controlled based on the measurement result by the first flow meter 22. The measurement position by the first flow meter 22 is not particularly limited, but is preferably, for example, closer to the vaporizer 24 than the measurement position by the second flow meter 21.

[0031] The first flow meter 22 may be, for example, a thermal or differential pressure flow meter, but is not limited to these examples and may use other measurement principles. Thermal flow meters may be, for example, cooling measurement methods, temperature difference measurement methods, or power consumption measurement methods. The cooling measurement method detects a temperature rise in a section where a Peltier element is installed and calculates the flow rate based on that temperature rise. The temperature difference measurement method measures the temperature of the fluid downstream and upstream of a heater installed in the fluid and calculates the flow rate based on the temperature difference between the two points. The power consumption measurement method adjusts the output to the heater so that the temperature difference between the downstream and upstream of the heater installed in the fluid is constant, and calculates the flow rate based on the power consumption of the heater at that time. Differential pressure flow meters may be, for example, detecting the pressure difference before and after a flow restrictor and calculating the flow rate from the pressure difference using the Hagen-Poiseuille law.

[0032] There are no particular limitations on second flow meter 21 as long as it measures the flow rate using a different measurement principle from first flow meter 22, but it is preferable that second flow meter 21 has a function of detecting air bubbles or foreign matter in supply pipe 32. Specifically, second flow meter 21 is preferably an ultrasonic flow meter. Furthermore, because installation and maintenance are easy, it is preferable that second flow meter 21 be a so-called clamp-on ultrasonic flow meter that can be installed on the outside of supply pipe 32 and can measure the flow rate inside supply pipe 32 from the outside.

[0033] The amount of liquid siloxane 31 supplied to vaporizer 24 is further controlled based on the measurement results of second flow meter 21. The measurement position of second flow meter 21 is not particularly limited, but is preferably, for example, closer to source material container 30 than the measurement position of first flow meter 22. Furthermore, in addition to setting the measurement position in this way, it is also preferable that the distance between the measurement position of first flow meter 22 and the measurement position of second flow meter 21 be 10 mm or more and 500 mm or less.

[0034] The flow velocity of the liquid siloxane 31 in the supply pipe 32 is preferably, for example, 1 m / s or less from the viewpoint of suppressing the generation of static electricity. Furthermore, the flow velocity of the liquid siloxane 31 is preferably 0.015 m / s or more from the viewpoint of increasing the production speed. When changing the flow rate, a response on the order of 0.1 to 1 second is required, and the distance between the measurement position by the first flow meter 22 and the measurement position by the second flow meter 21 is determined taking into consideration these flow velocities and the responsiveness of the first flow meter 22.

[0035] The MFC 25 controls the flow rate of the carrier gas sent to the mixer 23. The carrier gas is supplied to the mixer 23 via a supply pipe 36. The carrier gas is, for example, an inert gas such as nitrogen gas. Note that in FIG. 2, the supply device that supplies the carrier gas to the MFC is not shown.

[0036] The mixer 23 mixes the liquid siloxane 31 supplied from the supply pipe 32 with the carrier gas supplied from the MFC 25, and sends the mixture to the vaporizer 24. The mixer 23 mixes the carrier gas, which has been heated, with the liquid siloxane 31, for example, by increasing the pressure of the carrier gas before mixing.

[0037] Mixer 23, for example, has a valve (e.g., a piezoelectric actuator valve) therein, and adjusts the opening of the valve based on a signal from control unit 26. By adjusting the opening of the valve, the flow rate of liquid siloxane 31 supplied to vaporizer 24 is controlled. As a result, the flow rate of siloxane gas supplied to burner 34 is controlled.

[0038] The vaporizer 24 vaporizes the liquid siloxane 31 to form a siloxane gas. The vaporizer 24 reduces the pressure of a gas mixture of the liquid siloxane 31 and a heated carrier gas, for example, to vaporize the liquid siloxane 31. In the vicinity of the vaporizer 24, the influence of the temperature transmitted from the vaporizer 24 is large.

[0039] Control unit 26 receives the measurement results of first flow meter 22 and first flow meter 23, and controls the amount of liquid siloxane 31 supplied to vaporizer 24 based on these measurement results. In this embodiment, control unit 26 sends a control signal to mixer 23 and controls the flow rate of liquid siloxane 31 in mixer 23, thereby controlling the amount of liquid siloxane 31 supplied to vaporizer 24. Note that control unit 26 may not be provided, and control unit 4 may perform the above-mentioned functions of control unit 26 instead.

[0040] (Method of manufacturing glass particle deposit body) A method for manufacturing a soot glass deposit M according to an embodiment of the present disclosure is a method for manufacturing a soot glass deposit M using the above-described apparatus 1. In the following, an example will be described in which an ultrasonic flow meter having a function of detecting bubbles or foreign matter in the supply pipe 32 is used as the second flow meter 21.

[0041] The manufacturing method described below will be explained using the OVD (Outside Vapor Deposition) method as an example, but the present disclosure is not limited to the OVD method. The present disclosure can be applied to any method that generates and deposits glass particles from siloxane gas, without any particular restrictions, and can also be applied to, for example, the VAD (Vapor Phase Axial Deposition) method and the MMD (Multiburner Multilayer Deposition) method.

[0042] A method for manufacturing a soot glass deposit M according to an embodiment of the present disclosure includes a supplying step, a control step, and a depositing step. The supplying step is a step of supplying liquid siloxane 31 in a source container 30 to a vaporizer 24. The amount of liquid siloxane 31 supplied to the vaporizer 24 is controlled in the control step.

[0043] The control step is a step of measuring the flow rate of liquid siloxane 31 in supply pipe 32 with first flow meter 22 and controlling the amount of liquid siloxane 31 supplied to vaporizer 24 based on the measurement results of first flow meter 22. Furthermore, in the control step, the amount of liquid siloxane 31 supplied is further controlled based on the measurement results of second flow meter 21.

[0044] The first flow meter 22, which is located near the vaporizer 24, is significantly affected by the temperature transmitted from the vaporizer 24. Therefore, if the first flow meter 22 is a thermal flow meter, there is a risk of errors in the measurement results. Therefore, in this embodiment, an ultrasonic flow meter with low temperature dependency is used as the second flow meter 21, and the supply amount of liquid siloxane 31 is further controlled based on the measurement results of the ultrasonic flow meter, thereby reducing the effect of the temperature transmitted from the vaporizer 24.

[0045] Furthermore, in the control step, if the second flow meter 21 detects air bubbles or foreign matter in the supply pipe 32, it is preferable to determine that the measurement result by the first flow meter 22 is an abnormal value within a predetermined period (e.g., 10 seconds) after the detection of the air bubbles or foreign matter. Specifically, it is preferable to control the supply amount of liquid siloxane 31 without relying on the measurement result measured by the first flow meter 22 within the predetermined period. More specifically, it is preferable to control the supply amount of liquid siloxane 31 based only on the measurement result of the second flow meter 21, or based on the measurement result of the second flow meter 21 and the measurement result of the first flow meter 22 immediately before the detection of the air bubbles or foreign matter.

[0046] The deposition step is a step in which the siloxane gas vaporized by the vaporizer 24 is sent to the burner 34, and the siloxane gas is subjected to an oxidation reaction to deposit glass particles 35. Through the deposition step, a glass particle deposit body M is obtained.

[0047] Although the present embodiment has been described above, it goes without saying that the technical scope of the present invention should not be construed as being limited by the description of the embodiment. The present embodiment is merely an example, and it will be understood by those skilled in the art that various modifications of the embodiment are possible within the scope of the invention described in the claims. Thus, the technical scope of the present invention should be determined based on the scope of the invention described in the claims and its equivalents. [Explanation of symbols]

[0048] 1: (Glass particle deposit) manufacturing equipment 2: Reaction vessel 3: Lifting and rotating device 4,26: Control unit 10: Support rod 11: Starting rod 12: Exhaust pipe 20: Vaporization section 21:Second flow meter 22: 1st flow meter 23: Mixer 24: Vaporizer 25:MFC 30: Raw material container 31: Liquid siloxane 32, 36: Supply piping 33: Temperature control piping 34: Burner 35: Glass particles M: Glass particle deposit

Claims

1. supplying liquid siloxane to a vaporizer via a supply line; measuring the flow rate of the liquid siloxane in the supply pipe with a first flow meter, and controlling the supply amount of the liquid siloxane supplied to the vaporizer based on the measurement result of the first flow meter; a step of supplying the siloxane gas vaporized by the vaporizer to a burner, and causing an oxidation reaction of the siloxane gas to deposit glass particles; the controlling step further includes controlling the supply amount based on a measurement result of a second flow meter that measures the flow rate using a measurement principle different from that of the first flow meter. A method for producing a glass soot deposit.

2. the first flow meter is a thermal or differential pressure flow meter, The second flow meter is an ultrasonic flow meter. The method for producing a soot glass deposit according to claim 1 .

3. In the supply pipe, a measurement position by the first flow meter is located closer to the vaporizer than a measurement position by the second flow meter, the second flow meter has a function of detecting air bubbles or foreign matter in the supply pipe; When the second flow meter detects air bubbles or foreign matter in the supply pipe, the measurement result of the first flow meter is determined to be an abnormal value within a predetermined period after the detection of the air bubbles or foreign matter. The method for producing a soot glass deposit according to claim 2 .

4. In the supply pipe, a measurement position by the first flow meter is located closer to the vaporizer than a measurement position by the second flow meter, a distance between a measurement position of the first flow meter and a measurement position of the second flow meter is 10 mm or more and 500 mm or less; The method for producing a soot glass deposit body according to any one of claims 1 to 3.

5. a supply line for supplying liquid siloxane to the vaporizer; a vaporizer for vaporizing the liquid siloxane; a first flow meter that measures the flow rate of the liquid siloxane in the supply pipe; a control unit that controls the amount of the liquid siloxane supplied to the vaporizer based on the measurement result of the first flow meter; a burner that causes an oxidation reaction of the siloxane gas vaporized by the vaporizer to deposit glass particles; a second flow meter that measures the flow rate using a measurement principle different from that of the first flow meter, The control unit further controls the supply amount based on a measurement result by the second flow meter. Glass particle deposit manufacturing equipment.

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