JPS61205629A - Raw material feeder - Google Patents

Abstract

PURPOSE:To keep a raw material constantly in boiling state, to prevent the bumping of the material, and to enable the stable feeding of the material, by using a raw material tank to heat and evaporate the raw material and to supply the vapor to a reaction vessel under controlled flow rate, and attaching a means to cool the evaporated raw material gas to the tank. CONSTITUTION:The liquid raw material 2 reactive with oxygen or moisture in air is stored in an air-tight raw material tank 1, and evaporated with the heater 3. The generated raw material gas is transferred from the upper space 4 through the line 5 furnished with a shut-off valve 6, a control valve 7 and a flow-controlling device 8 to a reaction vessel (omitted in the figure) under controlled flow rate. In the above raw material feeding apparatus, an assistant vessel 11 furnished with a cooling means is connected to the upper space 4 via constricted connection channel 12. The apparatus enables the constant and stable boiling of the raw material and the stable flow control of the material even in the case of abrupt increase in the supply of the raw material.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to 5iCA!, which is used in the production of original fiber base materials or semiconductors, etc. The present invention relates to a raw material supply device that can stably guide a liquid raw material such as GeCl4 into a reaction vessel in a large amount while precisely controlling the flow rate.

<Prior Art> A case where the raw material supply device is a manufacturing device for a base material for a fiber will be described. The method for manufacturing optical fiber base material is as follows:
The so-called VAD method, external method, internal method, etc. are known. Among these, in the VAD method, which requires continuous supply of raw material gas for a long period of time, the liquid glass raw material is vaporized and the raw material gas is fed to a reaction vessel at atmospheric pressure or higher and burned in a hydrogen oxide burner or a plasma burner. In this method, a glass medium is generated and deposited in the axial direction on a rotating starting member to produce a rod-shaped porous preform, and this porous preform is further spun into a base fiber. For this reason, a raw material supply device that continuously and stably supplies the raw material gas to the reaction vessel was required. An example of such a raw material supply device is shown in FIG. According to the raw material supply device shown in FIG. 7, an airtight raw material tank 1 contains a raw material liquid 2 that reacts with dust or moisture in the atmosphere, and the raw material liquid 2 is disposed on the outer periphery of the raw material tank 1.
A heater 3 is attached to vaporize the . The upper space 4 of the raw material tank 1 is filled with raw material gas obtained by vaporizing the raw material liquid at the vapor pressure at the temperature of the raw material tank 1, and there is a gap between the upper space 4 of the raw material tank 1 and the reaction vessel (not shown). A pipe 5 for supplying raw material gas is arranged. Piping 5
An on-off valve 6, an automatic valve 7, and a flow meter control device 8 are installed in the . As the flowmeter control device 8, a quality 1 flowmeter (mass 70-controller) is widely used.

A piping 9 with an automatic valve 10 interposed therebetween is connected to the primary side of the flowmeter control device 8, and nitrogen gas is supplied through the piping 9. The automatic valve 10 is interlocked with the automatic valve 7, and when the raw material is being supplied, the automatic valve 7 opens and the automatic valve 10 is closed to flow the raw material into the reaction vessel, and when the material is not being supplied, the automatic valve 7 is closed and the automatic valve is closed. 10 is opened and nitrogen gas is flowed into the piping to purge the piping.

The procedure for introducing the raw material gas into the reaction vessel using the raw material supply device shown in FIG. 7 is as follows. When the raw material is not being supplied, the automatic valve 7 closes, and the automatic valve 10 opens to close the pipe 50.
The counter reactor side is purged with nitrogen gas. In order to start supplying raw materials from such a state, first, the heater 3 is heated to heat the raw material liquid in the raw material tuck, and the raw material gas pressure in the upper space 4 of the raw material tank is brought to a predetermined value higher than atmospheric pressure. do. For example, in order to make the raw material liquid 5tcz4 and the raw material gas pressure 1Kg/iG, the temperature of the raw material tank should be 8
Heat to 0°C.

Next, the automatic valve 10 is closed, the automatic valve 7 is opened, and the raw material gas is sent to the reaction vessel. At this time, the flow rate control device 8 controls the feed 1 of the raw material gas to a required flow rate.

At the end of raw material gas supply, automatic valve 7 is closed and automatic valve 1 is closed.
0 and parts the inside of the pipe 5 with nitrogen gas. moreover,
If supply of raw material gas is not restarted in a short time, heater 3
and cool the raw material tank. Furthermore, when restarting is scheduled relatively soon, the heater 3 is left on to keep warm.

<Problems to be Solved by the Invention> With the configuration shown in FIG.
For example, when the temperature is maintained at 80°C, the temperature inside the raw material tank is completely uniform.

In this state, heat convection and boiling due to temperature distribution do not occur in the raw material tank, and only gas-liquid phase changes occur at the liquid level in an equilibrium state. In such a situation, if you suddenly open the automatic valve 7 to send a large flow of raw material gas to the reaction vessel, even if the gas phase raw material gas flows out and the internal pressure of the raw material tank decreases, boiling will start stably. Moreover, in some cases, the internal pressure of the raw material tank becomes temporarily lower than the saturated vapor pressure of the raw material gas, resulting in bumping, making it impossible to stably supply raw materials with a controlled flow rate. has the disadvantage that the worst case scenario is damage to piping parts.

In addition, after the start of boiling, the raw material tank is in a completely steady state, and the wall temperature of the tank, the liquid temperature of the raw material, and the air temperature are approximately the same, so the outflow of latent heat caused by the sudden flow of raw material gas is extremely low. Even if the temperature increases, sufficient heat transfer from the wall or heater cannot be expected, and the liquid temperature continues to drop for a certain period of time.As a result, the primary gas pressure at flow rate control 1 & 2, which is approximately equal to the saturated vapor pressure, decreases, and the temperature remains constant. Stable light weight control using a control device that requires a primary and secondary pressure difference becomes impossible.

Therefore, in view of the above-mentioned drawbacks, the present invention creates a temperature distribution in the raw material tank even when the raw material tank is kept warm by a heater, thereby actively exchanging the gas-liquid phase and constantly boiling. to achieve stable boiling and prevent bumping.
In addition, even when the raw material supply increases rapidly, sufficient heat transfer from the heater is carried out to prevent a shortage of raw material supply and to maintain a stable IT system.
The purpose is to provide a raw material supply device that performs control.

Means for Solving Problems> The present invention, which achieves the above-mentioned objects, includes a raw material tank containing a raw material liquid that reacts with oxygen or moisture in the atmosphere, a means for heating this raw material liquid, and A mechanism for cooling the raw material gas vaporized in the raw material tank, in a raw material supply device comprising a pipe that guides the raw material gas vaporized in the raw material tank to a reaction vessel, and a device installed in the pipe for opening/closing and controlling the flow rate. The raw material tank is equipped with the following.

Effect> By providing a mechanism for cooling the raw material gas, it is possible to create a continuous temperature distribution within the raw material tank, activating the phase change of the gas-liquid phase, and stably boiling.

<Example> The present invention will now be described in detail with reference to Figures 1 to 6. Note that the same parts as in FIG. 7 are given the same reference numerals.

In Figures 1 to 6, 1 is a raw material tank, 2 is a raw material liquid, 3 is a heater, 4 is an upper space, 5 is a pipe, 6 is an on-off valve, 7°lO is an automatic valve, 8 is a flow rate control device, With 9Fi piping, this function is the same as before.

In FIG. 1, an auxiliary container 11 is attached to the upper lid of the raw material tank 1.
The auxiliary container 11 is connected to the upper space 4 of the raw material tank 1 by using a constricted opening as a connecting portion +12. Moreover, this auxiliary container 11 itself is cooled from the outside, and is equipped with water cooling or air cooling means (not shown as there are many known types).

Although the auxiliary container 11 shown in FIG.

When the auxiliary container 11 is communicated with the upper space 4 of the raw material tank 1 in this way, the raw material gas in the upper space 4 is transferred to the auxiliary container l.
Since the raw material gas is condensed in the tank 1, even if the automatic valve 7 is closed and raw material gas is not sent, the raw material gas will enter from the opening due to the condensation, and the condensed liquid will flow through the opening and flow into the raw material tank 1. I will be going back. That is, it is sufficient to increase the amount of cooling 1 of the auxiliary container 11 to a certain extent to generate heat convection and activate the gas-liquid phase change to bring about boiling.

Even if the automatic valve 7 is opened in such a state, since the raw material is already boiling, no unstable phenomenon will occur due to the start of boiling, and since heat transfer is ensured by cooling, the internal pressure drop in the raw material tank will be extremely small and the flow rate will be controlled. Does not adversely affect the equipment.

The configuration shown in FIG. 2 differs from that shown in FIG.
It is configured to communicate with the raw material rig/reater 1 through 3a and 13b. More specifically, the lower part of the auxiliary container 11 is connected to the piping 1.
3a into the raw material liquid 2 in the raw material tank 1, and the part other than the lower part (the upper part in FIG. 2) of the auxiliary container 11 is connected to the pipe 1.
It passes into the upper space 4 of the raw material tank 1 via 3b.

Therefore, the vaporized raw material gas enters the auxiliary container 11 through the pipe 13b, and the raw material condensed into liquid in the auxiliary container 11 enters the raw material liquid 2 in the raw material tank 1 through the pipe 131L. It turns out. The structure of FIG. 2 is as follows.
This becomes important when increasing the cooling of the auxiliary vessel 11, for example from air cooling to water cooling, increasing the circulation 1, for example 10
Regardless of the case where raw material gas of about 51/m is sent from one raw material tank to a reaction vessel, the flow rate is several tens of l/min to 1001/s.
This is useful when delivering raw material gas of about i+.

Furthermore, FIG. 3 shows another modification. When supplying a large flow of raw material gas from the raw material tank 1 to the reaction vessel, the auxiliary vessel 1
Since the circulation 1 caused by 1 becomes a burden υ on the side supplying the reaction vessel, the heat transfer 1 decreases, and as a result, there is a possibility that the raw material gas cannot be sufficiently sent to the reaction vessel. For this reason, the third
As shown in the figure, an on-off valve 14 may be interposed in the pipe 13b to the auxiliary container 11, and the on-off valve 14 may be closed during supply to the reaction container.

In this case, the on-off valve 14 between the auxiliary container 11 and the raw material tank 1 is used as the first automatic valve, and the automatic valve 7 is used as the second automatic valve. Before sending out, the first automatic valve 14 is opened), and
It is preferable to close the first automatic valve 14 immediately after opening the second automatic valve 7 or after a certain period of time. in this case,
The reason why the first automatic valve 14 is closed immediately after the second automatic valve 7 is opened or after a certain period of time is because the opening and closing of the valve changes from the liquid phase to the gas phase depending on piping resistance and the customer type for the gas phase in the raw material tank 1. Since there is a time delay until the state of phase change is affected, stable flow control is performed by shifting the timing of opening and closing.

Furthermore, the on-off valve 14 is an automatic valve, and this automatic valve is linked to a flow rate control device, so that when the flow rate sent from the flow rate control 8 is less than a constant 1, the automatic valve 14 is opened, and when it is higher, the automatic valve 1 is opened.
4 is closed, or when the flow rate is less than a certain amount, the automatic valve 14 is opened, and after a certain period of time when the flow rate has increased, the automatic valve 14 is opened.
You may also close it. The interlock between the flow rate control device 8 and the automatic valve 14 is such that when the control flow rate is changed over a wide range, the use of the circulation route including the auxiliary container 11 is managed by setting a threshold value for the control flow rate. This is because it is preferable.

4 to 6 show an example in which a cooling part is directly provided in the raw material tank 1 without providing an auxiliary container, unlike the previous explanation. That is, FIG. 4 shows a case where the upper lid 1a or upper part of the raw material tank 1 is provided with cooling fins 15, and FIG. 5 shows the upper lid 1! of the raw material tank 1. A case is shown in which a piping 16 for cooling LK2 or liquid cooling is provided, and FIG. 6 further shows a case in which a piping 17 for air cooling or liquid cooling is provided in the upper space 4 of the raw material tank 1. There are various other variations of these direct cooling configurations.

<Effects of the Invention> As explained above, according to the present invention, the raw material tank itself,
Alternatively, by cooling the upper space and forming a cooling circulation route, a temperature distribution is created and the exchange of the gas-liquid phase is activated, and boiling is constantly generated, thereby preventing stable boiling and boiling, and stably preventing boiling. can be controlled.

[Brief explanation of the drawing]

1 to 6 show embodiments of the present invention. FIG. 1 is a block diagram of one example, FIG. 2 is a block diagram of another example, FIG. 3 is a block diagram of another example, and FIG. 4 is a block diagram of another example. Block diagram with cooling fins, fifth
Fig. 6 and Fig. 6 are a diagram of a conventional structure equipped with cooling pipes, and Fig. 7 is a bottom view of a conventional structure. In the drawings, 1 is a raw material tank, 3 heaters, 4 is an upper space, 5 is piping, 6 is an on-off valve, 7 is an automatic valve, 8 is a flow rate control device, 11 is an auxiliary container, 13a and 13b are piping, 14 is 15 is a cooling fin, ] 6 and 17 are cooling pipes.

Claims (9)

[Claims] (1) A raw material tank containing a raw material liquid that reacts with oxygen or moisture in the atmosphere, means for heating this raw material liquid, piping that guides the raw material gas vaporized in the raw material tank to a reaction vessel, and this piping A raw material supply device comprising a device for opening/closing and controlling the flow rate interposed in the raw material tank, wherein the raw material tank is equipped with a mechanism for cooling the raw material gas vaporized in the raw material tank. (2) The raw material supply device according to claim 1, wherein the mechanism is formed of an auxiliary container that communicates with the raw material tank and is cooled. (3) The raw material supply device according to claim 2, wherein the auxiliary container communicates with an upper space of the raw material tank. (4) In the raw material supply device according to claim 2, piping is provided between the lower part of the auxiliary container and the raw material liquid in the raw material tank, and A raw material supply device characterized in that the upper space of the raw material tank is communicated with. (5) In the raw material supply device according to claim 3 or 4, the auxiliary container and the upper space of the raw material tank are communicated with each other via an on-off valve. Device. (6) In the raw material supply device according to claim 5, the on-off valve interposed between the auxiliary container and the raw material tank is a first automatic valve, and the opening and closing valve interposed between the auxiliary container and the raw material tank is a first automatic valve, and the opening and closing valve interposed between the auxiliary container and the raw material tank is a first automatic valve. The interposed opening/closing device is a second automatic valve, and the second
A raw material supply device characterized in that before opening the automatic valve, a first automatic valve is opened, and after opening a second automatic valve, the first automatic valve is closed. (7) In the raw material supply device according to claim 5, the on-off valve interposed between the auxiliary container and the raw material tank is an automatic valve, and the automatic valve is provided between the raw material tank and the reaction vessel. When the flow rate sent out from the flow rate control device is less than a certain amount, the automatic valve is opened, and when the flow rate is higher, the automatic valve is closed, or when the flow rate is less than a certain amount, the automatic valve is A raw material supply device characterized in that this automatic valve closes after a certain period of time after the amount of raw material is increased. (8) The raw material supply device according to claim 1, characterized in that a cooling mechanism is attached to the upper lid or upper part of the raw material tank. (9) A raw material supply device according to claim 1, characterized in that a cooling mechanism is provided in the upper space inside the raw material tank.