JPH05253401A - Boiling vessel - Google Patents

Abstract

PURPOSE:To decrease the quantity of droplets which are scattered from the free surface and released to the outside, associated with air current in a device where liquid is heated and evaporated in a vessel, such as a distiller and a concentrator. CONSTITUTION:When a heating source is near the central part of the vessel in a boiling vessel 1, after bubbles 5 are collected by a bubble collector 2, they are conducted to near the wall of the free surface inside the boiling vessel 1 by using a bubble conduit 3. And when the heating source is on or near the wall of the boiling vessel 1, bubbles 5 are conducted to near the wall of the free surface inside the boiling vessel 1 by using a bubble movement restraint cylinder. By releasing the bubbles 5 mainly near the wall of the boiling vessel 1, the scattering of the droplets 6 due to the burst of the bubbles 5, etc., takes place mainly near the wall of the boiling vessel 1. Thereby most of the droplets scattered from the free surface collide with the wall of the boiling vessel and are condensed, causing the quantity of the droplets released to the outside of the boiling vessel to be decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distiller, a concentrator or the like in which a container is filled with a liquid and heated by heating the liquid from the inside or the outside, which has a free liquid level inside the container. The present invention relates to the internal structure of a container and a device for reducing the amount of liquid droplets scattered from the free liquid surface into the air flow.

[0002]

2. Description of the Related Art In a situation where a liquid is heated and boils, liquid droplets are scattered above the liquid surface in the free liquid surface of the liquid inside the boiling container due to rupture of bubbles, rocking of the liquid surface, and the like. In addition, when bubbles generated in the liquid blow up on the liquid surface, it is possible that the droplets are torn off from the liquid surface and scattered due to the shearing force of the air flow. In this way, droplets scatter from the free liquid surface due to various causes inside the boiling container,
Accompanied by the air flow. Although many studies have been conducted on the entrainment phenomenon, that is, entrainment, the most recent study on the mechanism of entrainment is the International Journal of Heat and Mass Transfer Vol.
No. 1, pp. 1999 to 2014 (International Jou
rnal of Heat and Mass Transfer Vol. 27 (11) pp1999
-2014, 1984). In this paper, the formula for evaluating entrainment is derived. The definition of entrainment is given as the ratio of the mass flow rate of a droplet to the mass flow rate of an air stream. The entrainment evaluation formula in the above paper includes the vessel diameter, and it is shown that the entrainment increases as the vessel diameter increases. It is considered that the cause of the increase in entrainment due to the increase in the diameter of the boiling container is that the ratio of the liquid droplets scattered from the free liquid surface, which collide with and adhere to the container wall and condense, decreases. Droplets scattered from the free liquid surface need to be captured using a demister or the like. A conventional example of a demister is, for example, as described in JP-A-61-139800, a device for preventing drops from falling into an air stream and being re-accompanied by forming a gradient in the lower part of the demister. Has been done.

[0003]

According to the above-mentioned prior art paper, as the diameter of the boiling vessel increases, the amount of liquid droplets scattered with the air flow increases. Increasing the number of droplets not only increases the wetness of the air stream, but also the substance contained in the liquid in the distiller or the concentrator is contained in the droplets and discharged. Therefore, the distillation performance and the decontamination coefficient decrease.

The object of the present invention is to improve the distillation performance and the decontamination coefficient for a large boiling container by reducing the amount of liquid droplets discharged from the system by being accompanied by an air flow. To provide a device.

[0005]

The above object can be achieved by adding a device for guiding bubbles generated in a liquid as close to the container wall as possible. However, it is necessary to change the structure depending on the arrangement of the heating source inside the container. That is,
Since bubbles are generated near the heating source, when the heating source is near the center in the horizontal cross section of the container, a device for guiding the bubbles toward the container wall is required. On the other hand, when the heating source is arranged on the container wall or in the vicinity of the container wall, it is necessary to provide a device that blocks the bubbles generated near the heating source from moving to the center of the container.

[0006]

[Function] By discharging the bubbles generated near the heating source inside the liquid to the vicinity of the wall of the boiling container, the amount of the droplets scattered in the air flow that are attached to the container wall and condensed increases.
The amount of droplets entrained in the air stream is reduced. In a distiller, a concentrator, etc., it is possible to reduce the rate at which a substance contained in a liquid is released to the outside of a container by droplets, and it is possible to improve the distillation performance and decontamination coefficient in a large boiling container. ..

[0007]

EXAMPLE An example of the present invention will be described with reference to FIG.
The inside of the boiling container 1 is filled with a liquid. However, the liquid has a free liquid surface. Liquid is heater 4
It is heated and boiled. The heater 4 is arranged in the center of the boiling container 1. As the liquid temperature increases,
Bubbles 5 are generated near the heater 4 and rise in the liquid. When the bubble 5 reaches the free liquid surface, the bubble 5 bursts, rocks the liquid surface, and tears the liquid in the vicinity of the liquid surface. Scatter. Here, if there is no device for suppressing the movement of bubbles inside the boiling container 1, the bubbles 5 move in the liquid and spread over the entire horizontal cross section of the boiling container 1, as shown in FIG. Therefore, the bubble 5 causes the droplet 6 to be discharged from the entire free liquid surface to the space above the free liquid surface. When the apparatus becomes large and the diameter of the boiling vessel 1 becomes large, the average distance between the place where the droplets 6 are generated and the wall of the boiling vessel 1 becomes large, so that the proportion of the droplets that collide with the wall of the boiling vessel 1 and condense. Decrease. Therefore, by enlarging the diameter of the boiling container 1, the entrainment, which is the ratio of the mass flow velocity of the droplets to the mass flow velocity of the air flow, increases. In order to prevent this, a dome-shaped bubble collector 2 for collecting bubbles generated near the heater 4 is installed above the heater 4 in FIG. Several bubble conduits 3 for discharging bubbles to the upper part are attached to the upper part of the bubble collector 2. The bubbles generated near the heater 4 are temporarily
It is collected by the bubble collector and discharged to the free liquid surface through the bubble conduit 4. The outlet of the bubble conduit 4 is arranged near the wall of the boiling vessel 1. Further, the outlet of the bubble conduit 4 is arranged at a position slightly below the free liquid level so that the bubbles discharged from the bubble conduit 4 do not move to the central portion of the horizontal cross section of the boiling container 1. As described above, even when the bubbles 5 are generated near the center of the boiling container 1, the droplets 6 are discharged above the free liquid surface by discharging the bubbles 5 only near the wall of the boiling container 1. Even so, since most of the droplets 6 collide with the wall of the boiling container 1 and condense, the amount of the droplets 6 discharged to the outside of the boiling container 1 can be suppressed to a small amount.

A second embodiment of the present invention will be described with reference to FIG. The heating source is a coil-shaped heat transfer tube 7, which is arranged near the wall of the boiling container 1 in the liquid. The bubbles 5 are generated near the heat transfer tube 7. In order to prevent the bubbles 5 from reaching the central portion of the horizontal cross section of the boiling container 1 while rising in the liquid, a bubble movement suppressing cylinder 8 is installed inside the heat transfer tube 7. Since the bubble 5 is restricted in the direction of movement only by the bubble movement suppressing cylinder 8 to the upper side, the discharge of the bubble 5 from the free liquid surface is mainly performed in the vicinity of the wall of the boiling container 1. Therefore, most of the droplets 6 scattered due to the burst of bubbles collide with the wall of the boiling container 1 and are condensed, and the amount of the droplets discharged to the outside of the boiling container 1 can be suppressed. In FIG. 3, the bubble movement suppressing cylinder 8 is tapered so that the space between the bubble motion suppressing cylinder 8 and the wall of the boiling container 1 becomes narrower toward the upper part, but the cylindrical shape without the taper suppresses the scattering amount of the droplet 6. Is obtained.

A third embodiment of the present invention will be described with reference to FIG. A heating tank 9 is arranged so as to surround the boiling container 1 from the outside. The inside of the heating tank 9 is filled with a high-temperature liquid, for example, to heat the wall of the boiling container 1. Since the liquid inside the boiling container 1 is heated by the wall of the boiling container 1, the bubbles 5 are generated from the wall of the boiling container 1. Also in this case, similarly to the second embodiment, the movement direction of the bubbles 5 is limited to the upper side by installing the bubble movement suppressing cylinder 8 inside the boiling container 1 to generate the droplets 6 from the free liquid surface. Is mainly performed near the wall of the boiling container 1. As a result, most of the droplets 6 scattered due to the bursting of bubbles collide with the wall of the boiling container 1 and condense, and the amount of droplets discharged to the outside of the boiling container 1 can be suppressed.

A fourth embodiment of the present invention will be described with reference to FIG. The lower part of the free liquid surface is similar to that of the first embodiment, but the gas above the free liquid surface immediately flows toward the central part of the container and prevents the liquid droplets from entraining in the central part of the container. A rectifying cylinder 10 is provided above. The gas discharged near the wall of the boiling container 1 flows upward by the straightening cylinder 10, so that the effect of the droplets 6 adhering to and condensing on the wall surface is further improved. Further, the installation of the straightening cylinder 10 simultaneously increases the area of the wall, and the straightening cylinder 1 is installed.
Even at 0, the effect of adhering and condensing the droplets 6 can be expected.
In the second and third embodiments, the same effect can be obtained by extending the bubble movement suppressing cylinder 8 above the liquid surface.

A fifth embodiment of the present invention will be described with reference to FIG. In addition to the structure of the fourth embodiment, a demister 11 is added below the air flow outlet 12. The liquid droplets 6 that are finally entrained in the air flow are not attached to the wall surface of the boiling container 1 and condensed, and do not fall due to gravity.
By capturing with the droplets 6 outside the boiling container 1
Is to be released.

[0012]

According to the present invention, it is possible to increase the amount of droplets that adhere to the container wall and condense, so that it is possible to reduce the amount of droplets entrained in the air flow. As a result, it is possible to improve the distillation performance and the decontamination coefficient when the device is enlarged in a distiller, a concentrator, or the like. Further, since the amount of droplets entrained in the airflow can be reduced, the structure of a device such as a demister that captures droplets can be simplified.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a boiling container having a heating source in a central portion.

FIG. 2 is a cross-sectional view of a boiling container without restrictions on rising bubbles.

FIG. 3 is a sectional view of a boiling container having a heating source near the container.

FIG. 4 is a cross-sectional view of a boiling container having a heating source on the outside of the container wall.

FIG. 5 is a cross-sectional view of a boiling container for rectifying the gas above the liquid surface.

FIG. 6 is a cross-sectional view of a boiling container in which a demister is arranged near the airflow outlet.

[Explanation of symbols]

1 ... Boiling container, 2 ... Bubble collector, 3 ... Bubble conduit, 4 ... Heater, 5 ... Bubble, 6 ... Droplet.

Claims (6)

[Claims] 1. A boiling container comprising a container for heating and boiling a liquid having a free liquid surface and a heating source for heating the liquid, which is generated in the liquid below the free liquid surface of the liquid. A boiling container having a passage for guiding bubbles toward the wall of the boiling container. 2. The heating source for the liquid according to claim 1, wherein the heating source for the liquid is arranged near the center in a horizontal cross section of the container, and the heating source is covered with a dome-shaped space for collecting bubbles generated near the heating source. A boiling container provided with a passage for guiding bubbles from the wall toward the wall of the boiling container. 3. The heating source for the liquid according to claim 1, wherein the heating source for the liquid is arranged near a wall of the boiling container in a horizontal cross section of the container,
A boiling container provided with a cylindrical partition plate so as to prevent bubbles generated near the heating source from passing through the liquid to the vicinity of the center of the container and to raise bubbles near the container wall. 4. The liquid source according to claim 1, wherein the heating source of the liquid is outside the container, the liquid in the container is heated by the container wall, and the bubbles generated from the container wall pass through the liquid and move to the vicinity of the center of the container. A boiling container provided with a cylindrical partition plate so as to prevent this and to raise bubbles near the container wall. 5. The boiling container according to claim 1, wherein a rectifying device for controlling the flow of gas above the free liquid surface is provided. 6. The boiling container according to claim 1, wherein a droplet collecting device is provided above the free liquid surface.