JPH04119928A - Apparatus for generating gaseous starting material for glass - Google Patents

Abstract

PURPOSE:To stably and uniformly vaporize a large amt. of liq. starting material for glass by placing a pair of electrodes for generating an electric field opposite to each other at the ejecting end of a pipe for feeding gaseous starting material and the vaporizing part of a vaporizer vessel. CONSTITUTION:A feed pump 35 is operated to feed liq. starting material 45 for glass in a tank 31 to the ejecting end 34 of a pipe 32 for feeding liq. starting material through the pipe 32 and a flow rate controller 36. Voltage is impressed between electrodes 42, 43 for generating an electric field placed opposite to each other at the ejecting end 34 and the vaporizing part 40 of a vaporizer vessel 37. The liq. starting material 45 electrified in a generated electric field is dropped on the vaporizing part 40 and vaporized by heating to the b.p. or above with a heater 38. The resulting gaseous starting material is sent to a prescribed reaction system through a discharge pipe 41.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a frit gas generating device used in the synthesis of quartz-based glass in the communications and optical fields.

"Conventional technology" Synthesis technology for silica-based glass, which is typified by optical fiber base material, involves two methods: vaporizing liquid glass raw material to create frit gas, and reacting the glass raw material gas in a reaction system to generate glass particles. a means for depositing glass particles to create a porous glass body; a means for dehydrating the porous glass body;
Combinations with methods for producing transparent glass bodies (base materials) through transparent vitrification are widely practiced.

As a means for vaporizing the liquid frit mentioned above, that is, a means for producing frit gas, an apparatus shown in FIGS. 6 and 7 is provided.

First, the apparatus shown in FIG. 6 will be explained.

In FIG. 6, a raw material liquid supply pipe 4 equipped with a feed pump 3 is piped between a raw material tank 1 and a vaporization container 5, and the raw material liquid supply pipe 4 transfers the liquid glass raw material 2 in the raw material tank 1 to the vaporization container. Timely supply within 5 days.

The vaporization container 5 includes a heater 6 and a pressure gauge 7, and is covered with a heat insulating material 8, and the heater 6 heats the liquid glass raw material 2 in the vaporization container 5 to evaporate it.

Furthermore, the bubbling gas pipe 10 connected to the carrier gas pump 9 is equipped with a mass flow controller (MFC) 15 in each part of the branch pipe 11, the merging pipe 12, and the wood pipe 14 between the branch point and the merging point. Preparation, branch pipe 1
2 and the merging pipe 14 are inserted into the vaporization container 5, the carrier gas sent from the carrier gas pump 9 to the bubbling gas pipe 10 is divided into the branch pipe 11 and the wood pipe 14.

The carrier gas flowing through the branch pipe 11 is blown into the vaporization container 5 and flows through the confluence pipe 12 carrying the liquid frit 2 evaporated there, that is, the frit gas.

Thus, the frit gas flowing through the confluence pipe 12 flows through the main pipe 1.
After being diluted by merging with the carrier gas flowing through 4, it flows into a predetermined reaction system.

Next, the apparatus shown in FIG. 7 will be explained.

In FIG. 7, a raw material liquid supply pipe 4 equipped with a foot pump 3 and an MFC 15 is installed between the raw material tank 1 and the vaporization container 5. is supplied into the vaporization container 5 at the appropriate time.

The vaporization container 5 equipped with a heater 6 and a pressure gauge 7 has a gas outlet '1! '1B is connected, and the heater 6 is connected to the vaporization container 5.
Since the liquid frit 2 inside is heated, the liquid frit 2 evaporated in the vaporization container 5, that is, the frit gas, flows into a predetermined reaction system via the gas extraction pipe 16.

``Problem to be Solved by the Invention j'' In the case of the apparatus shown in FIG. Raw material (glass raw material gas)
is transported to the reaction system by a carrier gas.

At this time, the flow rate of the frit gas is controlled with high precision via the MFC 15 provided in each part of the piping, but in practice it is difficult to stably supply the frit gas over a long period of time.

The cause of this is that the MFC1
The sensor portion of No. 5 is susceptible to temperature deterioration, condensation of vaporized raw materials occurs in the valves of the piping system, and clogging occurs due to contamination of the piping system.

In addition to the above, the liquid glass raw material 2 in the vaporization container 5
Bubbles burst due to localized boiling of the gas, creating a limit where the pressure inside the vaporization container 5 fluctuates, which also impedes the flow rate controllability (stable supply) of the frit gas. .

In addition, since the temperature of the liquid frit 2 in the vaporization container 5 tends to be different between the center of the container and the outer periphery of the container, especially when vaporizing a large amount of liquid frit 2, the temperature of the liquid frit 2 tends to be different. It is necessary to increase the size of the device, such as by increasing the thermal area.

On the other hand, in the case of the apparatus shown in FIG. 7, the entire amount of liquid frit 2 supplied into vaporization container 5 is vaporized instantly, so the amount of liquid frit 2 supplied into vaporization container 5 is simply controlled. MFC1 required for such control
5 is also only provided in the raw material liquid supply pipe 4 in the low temperature range, so the piping configuration is simplified and failure of the MFC 15 is less likely to occur.

Therefore, when using the apparatus shown in FIG. 7, it is possible to sufficiently control the flow rate (stable supply) of the frit gas with a simple device configuration, and it can be said that the reliability in supplying the frit gas is improved.

However, the apparatus shown in FIG. 7 also has a large amount of liquid glass raw material 2.
It is difficult to vaporize for the following reasons.

For example, when the liquid frit 2 in the form of droplets or mist is continuously introduced into the vaporization container 5 and vaporized in order to facilitate the evaporation of the liquid frit 2, the vaporization section of the vaporization container 5 ( Due to the surface tension of the liquid raw material #42 generated on the heater 6 side), the vaporized gas pressure, etc., the unevaporated raw material (droplets, mist) floats up from the vaporized part, and moreover, there is a gap between the unevaporated raw material and the vaporized part. Since the intervening evaporation raw material (gas layer) prevents heat conduction from the heater 6 side to the unevaporated raw material side, the vaporization rate of the liquid glass raw material 2 decreases.

In view of this technical problem, the present invention aims to provide a frit gas generation device that can stably and homogeneously vaporize a large amount of liquid glass raw material without increasing the size of the device.

Means for Solving the Problems In order to achieve the intended purpose of the present invention, a raw material liquid supply pipe having a flow rate controller is installed between the raw material liquid link and the vaporization container, and the raw material liquid supply pipe is connected to the raw material liquid supply pipe. In a frit gas generation device in which a suction end is connected to a raw material liquid tank and a discharge end of a raw material liquid supply pipe is connected to a vaporization container, a pair of electric field generating electrodes is connected to a raw material liquid supply pipe. It is characterized in that the end portion side and the vaporization portion side of the vaporization container are disposed relative to each other.

In the case of the device of the present invention, when supplying droplets of liquid glass raw material into the vaporization container and vaporizing it, as in the case of the raw material liquid tank → raw material liquid supply pipe → raw material liquid tank, a voltage is applied between the pair of electrodes. Apply.

In such a case, droplets of the liquid glass raw material supplied into the vaporization container from the discharge end of the raw material liquid supply pipe are charged with a polarity different from that of the vaporization part of the vaporization container.

In this way, the liquid glass raw material is attracted to the vaporization section of the vaporization container and is vaporized reliably and stably.

rExample” Regarding the example of the frit gas generator according to the present invention,
This will be explained with reference to the drawings.

1 to 3, 31 is a raw material tank, 32 is a raw material liquid supply pipe, 37 is a vaporization container, 41 is a gas extraction pipe, 42
．． Reference numeral 43 indicates a pair of electrodes, and 44 indicates a power source.

These raw material tank 31, raw material liquid supply pipe 32, vaporization container 3
7. The gas extraction pipe 41 has heat resistance, corrosion resistance, mechanical properties,
The inner electrodes 42 and 43 are made of well-known materials such as metals, glass, and ceramics having insulating properties and the like, and the inner electrodes 42 and 43 are also made of well-known conductive materials.

The raw material liquid supply pipe 32 is provided with a feed pump 35 and a flow rate controller 38 between a suction end 33 and a discharge end 34. The device 36 also includes a mass flow controller (MFC), which is publicly known.

The raw material liquid supply pipe 32 equipped with the feed pump 35 and the flow rate controller 36 has a suction end 33 inserted into the raw material tank 31 and a discharge end 34 inserted therein.
The raw material tank 31 and vaporization container 37 are in communication with each other.

Note that when the raw material tank 31 is equipped with a pressurized liquid feeding means, the foot pump 35 of the raw material liquid supply pipe 32 may be omitted.

The vaporization container 37 has an electric heater 38 below the bottom of the container.
In addition, the container body is equipped with a pressure gauge 39, and the bottom side of the container where the heater 38 is located is connected to the vaporizer 40.
It becomes.

A heat insulating material (not shown) is provided around the vaporization container 37 for the purpose of heat retention.

The above is common to each of the embodiments shown in FIGS. 1 to 3, but the embodiments differ in the following aspects.

In the embodiment shown in FIGS. 1 and 2, one end of the gas extraction pipe 41 is connected to the vaporization container 37, and the other end is connected to a reaction system (not shown).

In the embodiment shown in FIG. 83, the gas extraction pipe 41 is omitted, and the open end of the vaporization container 37 is inserted into the axial center of an oxyhydrogen flame burner 46 having a multi-tube structure.

In the case of the embodiment shown in FIG. 1, one electrode 42 is wound into a coil and placed on the outer periphery of the discharge end 34 of the raw material liquid supply pipe 32, and the other electrode 43 is formed into a planar shape and is arranged around the discharge end 34 of the raw material liquid supply pipe 32.
7 on the vaporization section 40 side.

In the case of the embodiment shown in FIGS. 2 and 3, the raw material liquid supply pipe 32
One electrode 42 disposed on the side of the discharge end 34 is pulled out from the front of the discharge end 34 through the axis inside the discharge end 34 to the outside of the tube end, and the pulled out electrode end is The other electrode 43, which is branched and arranged on the side of the vaporizing section 40 of the vaporizing container 37, is constructed in the same manner as that shown in FIG. 1.

In addition, the inner electrodes 42 and 43 in FIGS. 1 to 3 are
Both are connected to a power source 44.

In FIG. 3, 45 indicates a liquid glass raw material, 47 indicates a glass rod made of quartz glass, and 48 indicates a porous glass body.

As the liquid glass raw material 45 in the above, in addition to 5iC1n for producing the main component 5i02 of quartz glass,
GeCIa, TiCl for producing subcomponents of silica glass (for refractive index control) such as GeO2 and TlO2
Various metal halides (liquid) such as No. 11 can be mentioned.

In the embodiment shown in FIGS. 1 to 3, when the liquid glass raw material 45 is vaporized, the following occurs.

The feed pump 35 is operated to suck the liquid glass raw material 45 in the raw material tank 31 from the suction end 33 of the raw material liquid supply pipe 32, and while the flow rate at this time is controlled by the flow rate controller 36, the liquid glass raw material 45 is The raw material liquid is supplied from the discharge end 34 of the raw material liquid supply pipe 32 into the vaporization container 37 .

In the vaporization container 37 into which the liquid frit 45 is supplied, the vaporization section 40 is heated to a temperature higher than the boiling point of the liquid frit 45 via the heater 38 and is maintained at a predetermined internal pressure so that the entire container is heated. It is kept warm.

Therefore, the liquid glass raw material 45 that becomes droplets from the discharge end 34 of the raw material liquid supply pipe 32 and drops onto the vaporization section 40 in the vaporization container 37 comes into contact with the vaporization section 40 and instantaneously evaporates (vaporizes).

When the liquid glass raw material 45 is vaporized, the pair of electrodes 42
．． A voltage is applied between 43 and 43.

For example, the electrode 42 is a negative electrode (-), and the electrode 43 is an anode (+
) (or vice versa), when a voltage is applied between these electrodes 42 and 43, the discharge end 34 of the raw material liquid supply pipe 32
The liquid glass raw material 45 passing through is negatively charged by the electrode 42, and the vaporization section 40 of the vaporization container 37 is positively charged by the electrode 43.

Therefore, the negatively charged liquid glass raw material 45 is attracted to the positively charged vaporizer 40 and is reliably and sufficiently vaporized there.

Of course, at this time, the vaporized gas layer does not remain on the vaporizing section 40 and the heat conduction to the liquid glass raw material (droplets) is not inhibited.

In the embodiments shown in FIGS. 1 and 2, the vaporized liquid glass raw material, that is, the glass raw material waste, is sent to a predetermined reaction system via the gas extraction pipe 41, and is produced as glass fine particles by the reaction there. Ru.

The glass raw material gas in the embodiment shown in FIG.
7 to form a porous glass body 48.

Next, an experimental example regarding the device of the present invention will be explained.

In this experimental example, the apparatus illustrated in FIG. 2 was used. The specifications of its main parts are as follows.

The inner diameter of the vaporizing section 40 in the vaporizing container 37 is 150 mm.

The heating temperature of the vaporization container 37 by the heater 38 was set to 250°C.

One electrode 42 was made of 20 branched electrode rods, and the other electrode 43 had approximately the same area as the vaporization part 40.

The distance from the lower end of the multi-branched electrode 42 to the vaporization section 40 is 3 m.
■It is.

The voltages applied to the picture electrodes 42 and 43 are as shown in FIGS. 4 and 5.

The liquid glass raw material 45 consists only of silicon tetrachloride (SiC+4).

The amount of liquid glass raw material 45 supplied from the raw material tank to the vaporization container 37 via the raw material liquid supply pipe 32 equipped with a flow rate controller 36 is 100 g/in.

The specifications of the apparatus illustrated in FIG. 2 were set as described above to vaporize the liquid frit 45, and at this time, the pressure fluctuation in the vaporization container 37 and the flow rate of the frit gas on the gas extraction pipe 41 side were measured. .

The results are shown in FIGS. 4 and 5.

As is clear from FIGS. 4 and 5, the voltage is 20
When the voltage was 0 V or more, the pressure fluctuation inside the vaporization container 37 was small, and 100 g/win of frit gas could be stably obtained on the gas extraction pipe 41 side.

However, when the voltage is Ov, 100V, which is too low relative to the amount of liquid frit supplied, the entire amount of liquid frit 45 supplied into the vaporization container 37 cannot be vaporized, and within a few minutes after the start of the experiment, The above-mentioned pressure fluctuation caused the amount of generated gas to become unstable, and glass raw material gas could not be stably obtained on the gas extraction pipe 41 side. In addition, 20 to 30 minutes after the start of the experiment, 4 of the unexploited liquid glass raw materials
5 filled the vaporization container 37, and the experiment had to be stopped.

"Effects of the Invention" The frit gas generation device δ according to the present invention has a basic configuration mainly consisting of a raw material liquid tank, a vaporization container, and a raw material liquid supply pipe with a flow rate controller, and simply combines a pair of electrodes. In addition to securing these technical advantages, such as simplifying the flow path configuration, controlling the flow rate of liquid glass raw materials, increasing the lifespan of the flow rate controller, and downsizing the vaporization vessel, the function of the paired electrodes enables A large amount of liquid glass raw material can be vaporized stably and homogeneously.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram schematically showing a first embodiment of the device of the present invention, FIG. 2 is an explanatory diagram schematically showing a second embodiment of the device of the present invention, and FIG.
The figure is an explanatory diagram schematically showing the third embodiment of the device of the present invention, and FIGS. 6 and 7 are explanatory diagrams schematically showing various conventional devices. 31... Raw material tank 32... Raw material supply pipe 33... Suction end 34... Discharge end 36... Flow rate controller 37 ...... Vaporization container 38 ... Heater 40 ... Vaporization section 42 ... Electrode 43 ... Electrode 44 ... Power supply 45・・・・・・Liquid glass raw material

Claims (1)

[Claims] A raw material liquid supply pipe having a flow rate controller is piped between the raw material liquid tank and the vaporization container, and the suction end of the raw material liquid supply pipe is connected to the raw material liquid tank, and the discharge end of the raw material liquid supply pipe is connected to the vaporization container. In the connected frit gas generators, a pair of electrodes for generating an electric field are arranged relative to each other on the discharge end side of the raw material liquid supply pipe and on the vaporization section side of the vaporization container. Glass raw material gas generator.