JPH04322736A - Raw material feeder - Google Patents

Abstract

PURPOSE:To stabilize the supply of a raw material by obtaining a raw gas saturated with the vapor of a raw liq. even when the raw liq. is decreased. CONSTITUTION:A bubbling gas is introduced into a raw liq. 2 in a closed vessel 1 from a bubbling gas inlet pipe 3 to form bubbles, and an ultrasonic wave is radiated into the raw liq. Consequently, the bubbles in the raw liq. are micronized by the irradiation with the ultrasonic wave, and the contact area between the gaseous phase and liq. phase is increased. Even when the raw liq. is decreased and the contact time between the gaseous phase and liq. phase is reduced, the extraction efficiency sufficient to compensate for the decrease is attained. Accordingly, the raw gas saturated with the raw liq. vapor is obtained even when the raw liq. is decreased, and the supply of the raw material is stabilized for a long time.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is a bubbling-type raw material supply device that mixes (bubble) raw material gas etc. in a gas phase gas at a fixed ratio by passing gas as bubbles through a liquid in which raw material gas is dissolved. Regarding. This bubbling-type raw material supply device is used in fields such as the production of optical fibers by the VAD method and the production of thin films by the CVD method.

0002

[Prior Art] When manufacturing optical fibers by the VAD method or thin films by the CVD method, it is important that not only the ingredients of the raw materials are stable, but also that the supply amount of the raw materials is stable. Desired. For this purpose, it is required that the components of saturated steam in the gas phase be stable and that the gas flow rate be stable.

In such cases, conventionally, a saturator (bubbler) is used to introduce bubbling gas into a solution in which the raw material gas is dissolved in a closed container to generate air bubbles, thereby reducing the amount of gas in the saturator. After the gas phase is saturated with the vapor of the raw material liquid, the saturated vapor is supplied as a raw material through a raw material supply line.

[0004] In such a raw material supply device, as the raw material is extracted as vapor by bubbling, the solution decreases, and the contact time between the gas phase and the liquid phase becomes shorter, or the temperature of the solution or the temperature of the solution decreases. There is a problem in that the concentration of the raw material gas to be extracted, that is, the amount of raw material supplied, becomes unstable due to disturbance factors such as changes in the saturated vapor pressure due to changes in the temperature of the bubbling gas.

In other words, when the solution decreases, the residence time of gas bubbles in the solution decreases, the contact time for the gas bubbles to become saturated with liquid phase components becomes shorter, and the vapor flow into the bubbles becomes shorter. The degree of contamination becomes low and saturation is no longer achieved. Also, when the temperature of the solution or the temperature of the bubbling gas changes,
The saturated vapor pressure changes, and as a result, the raw material gas concentration changes even if it is saturated. As a result, the amount of raw materials supplied becomes unstable.

[0006] Conventionally, therefore, the influence of fluctuations in ambient temperature has been suppressed as much as possible by placing the closed container in a thermostatic chamber. In other words, the amount of raw material supplied is determined by the saturated vapor pressure and the bubbling gas flow rate, so by controlling the saturated steam pressure by controlling the temperature of the closed container and controlling the bubbling gas flow rate by a gas flow controller, the raw material supply amount is determined by the saturated vapor pressure and the bubbling gas flow rate. Trying to control the amount.

[0007]

However, even if the temperature of the closed container is controlled and the bubbling gas flow rate is controlled as in the conventional method, there is a problem in that the amount of raw material supplied is not stabilized. That is, if the contact time between the gas phase and the liquid phase decreases due to a decrease in the solution, and the inside of the bubble becomes no longer saturated with steam, the concentration of the raw material gas changes, and the calculated raw material supply amount cannot be obtained.

[0008] In view of the above, the present invention provides an improved raw material that can obtain a gas phase component saturated with the vapor of the raw material liquid, regardless of the decrease in the raw material liquid, and stabilize the supply amount of the raw material. The purpose is to provide a feeding device.

[0009]

[Means for Solving the Problems] In the raw material supply device according to the present invention, bubbling gas is introduced into the liquid phase of the raw material liquid in the closed container through the introduction pipe, and is made to form bubbles. Ultrasonic waves are applied to the liquid phase of this sealed container by an ultrasonic generator. There, the bubbles are broken up into small pieces by ultrasonic waves. It is the contact efficiency between the bubbles and the solution that determines the extracted gas concentration.
In other words, it is the contact time and contact area between the gas phase and the liquid phase. In this case, as the bubbles become smaller, the surface area per unit volume increases, and as a result, the contact area between the gas phase and the liquid phase increases. Therefore, the contact efficiency between the gas phase and the liquid phase is improved, the extraction efficiency of the raw material dissolved in the raw material liquid is increased, and even when the raw material liquid decreases, gas phase components saturated with the vapor of the raw material liquid can be obtained. This makes it possible to stabilize the supply of raw materials.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a saturator which is a raw material supply device according to an embodiment of the present invention, in which a closed container 1 contains a solution 2 in which a raw material gas is dissolved. A bubbling gas introduction pipe 3 is attached to the upper left side of the closed container 1, and a raw material gas outlet pipe 4 is attached to the upper right side. An ultrasonic generator 5 is attached to the closed container 1, and its diaphragm 6 is placed in the solution 2.

One end of the bubbling gas introduction pipe 3 opens near the bottom of the closed container 1, and the bubbling gas is introduced into the solution 2 through this pipe 3. The bubbling gas introduced into the solution 2 becomes bubbles and rises in the solution 2. As these bubbles rise in the liquid phase of solution 2, they come into contact with solution 2, and the solution 2
steam enters.

At this time, the diaphragm 6 of the ultrasonic generator 5 vibrates and ultrasonic waves are emitted into the solution 2. Due to this ultrasonic radiation, the bubbles are shaken and broken into small pieces. By dividing the bubbles, the surface area of the bubbles per unit volume increases, and as a result, the contact area between the gas phase and the liquid phase increases, and the extraction efficiency of the raw material gas improves, even if the solution 2 decreases. Gas completely saturated with raw material can be led off from the gas outlet pipe 4. In other words, whether or not the gas phase inside the bubbles is saturated with the vapor of solution 2 is determined by the contact time and contact area between the gas phase and the liquid phase. Increasing the contact area can compensate for the decrease in contact time.

[0013] As a result, the vapor in the bubbles becomes saturated even at a lower liquid level than before, and fluctuations in the derived gas concentration due to fluctuations in the liquid level of the solution 2 can be reduced, making stable bubbling possible for a long time. . In fact, when we measured the temporal change in extracted gas concentration, we obtained a graph like the one shown in Figure 2. In FIG. 2, ○ marks are data obtained with a bubbler equipped with the above-mentioned ultrasonic generator 5 according to the present invention, and ×
The mark is data obtained with a conventional bubbler without an ultrasonic generator. From Figure 2, it can be seen that in the conventional method, the solution 2 decreases over time, and as a result, the liquid level lowers and the contact time between the gas phase of the bubbles and the liquid phase becomes shorter, and the extracted gas concentration gradually decreases. On the other hand, by emitting ultrasonic waves to make the bubbles smaller, even if the solution 2 decreases, the liquid level drops, and the contact time between the gas phase and the liquid phase becomes shorter, the concentration of the extracted gas decreases less. It can be seen that it is possible to obtain a raw material gas with a stable concentration.

[0014] Therefore, by simply controlling the flow rate of the bubbling gas fed into the gas introduction pipe 3 using a gas flow rate controller (not shown), the supply amount of the raw material can be stabilized over a long period of time regardless of the decrease in the solution 2. .

In the above embodiment, the diaphragm 6 of the ultrasonic generator 5 was placed in the solution 2, but since it is sufficient to emit ultrasonic waves into the solution 2, it is necessary to vibrate the wall surface of the closed container 1. You can also do this. Furthermore, although not mentioned in the description of the above embodiments, it is of course also possible to use a configuration in which the closed container 1 is housed in a constant temperature bath or the like and its temperature is controlled.

[0016]

[Effects of the Invention] As described above with respect to the embodiments,
According to the raw material supply device of the present invention, the bubbles of bubbling gas in the raw material liquid are pulverized by ultrasonic irradiation to increase the contact area between the gas phase and the liquid phase, thereby improving the extraction efficiency of the raw material gas. It is possible to prevent the extracted gas concentration from fluctuating due to a decrease in liquid, etc., and to stabilize the amount of raw material supplied over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a raw material supply device according to an embodiment of the present invention.

FIG. 2 is a graph showing temporal changes in extracted gas concentration.

[Explanation of symbols]

Claims (1)

[Claims] 1. A closed container containing a raw material liquid, a pipe that introduces gas into the raw material liquid to generate bubbles, and an ultrasonic generator that emits ultrasonic waves into the raw material liquid in the sealed container. and a pipe for leading out the gas from the sealed container.