JPS6044702A - Method and device for generating steam by surface evaporation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD The present invention relates to a method and apparatus for generating steam at a constant concentration.

Prior art and its problems In animal inhalation tests to evaluate the toxicity of harmful substances such as organic solvents that exist as liquids at room temperature and normal pressure, or in tests for the removal of these harmful substances, it is necessary to generate low-concentration organic solvent vapors. .

Conventionally, this type of steam generator employs a forced vaporization type or a bathoring type. Figure 1 shows a forced vaporization steam generator. In this method, the liquid to be evaporated is added to the evaporator 1 from the line 6 while the evaporator 17 is heated to a predetermined temperature by the heating means 2, and air is sent into the evaporator 1 from the line 4. The vapor generated by vaporizing the liquid on the inner surface is taken out from line 5 as generated vapor.

In a bubbling steam generator, a predetermined amount of liquid to be evaporated is loaded into an evaporating pot, and air is bubbled into the liquid while heating it to form bubbles, thereby generating steam.

In a forced vaporizer, the concentration of generated vapor is controlled mainly by changing the discharge flow rate of the liquid feed pump. Fluctuations in the discharge flow rate of the liquid feeding pump directly affect fluctuations in the concentration of generated steam, so that the pulsating flow of the pump or the like causes the concentration of steam to fluctuate. Further, a liquid feeding pump for generating vapor at a low concentration of 10 ppm or less is quite small, and it is difficult for this type of pump to supply liquid stably. Further, the concentration of generated vapor can only be changed within this pump flow rate adjustment range. In addition, the liquid dripped onto the inner wall of the evaporating pot causes the temperature distribution on the inner wall of the evaporating pot to become non-uniform, thereby causing fluctuations in the concentration of generated vapor. As described above, the forced vaporization type steam generator cannot stably obtain a desired steam concentration over a long period of time.

In a bubbling steam generator, fluctuations in the concentration of generated steam depend on the bubbling state. The bubbling state is influenced by various factors such as air flow rate, blowing pressure, liquid depth, and liquid temperature. Since fluctuations in these factors cannot be completely eliminated, the concentration of generated steam in a bubbling steam generator varies considerably.

"L Riji and Dan" 5. The purpose of the present invention is to provide a steam generation method and an apparatus therefor that can eliminate the drawbacks of the prior art and easily and stably generate steam from low to high concentrations. shall be.

In other words, in the present invention, air having approximately the same temperature as the liquid through indirect heat exchange with the liquid is placed on the surface of the liquid contained in a funnel-shaped cylinder whose cross-sectional area decreases downward. Spraying while keeping the height of the surface of the liquid constant; evaporating the liquid; and generating steam? A steam generation method consisting of a container containing the liquid to be evaporated, a funnel-shaped cylinder whose cross-sectional area decreases downward, an air introduction pipe, and an overflow part. The funnel-shaped cylinder is located within the container, the air introduction tube passes through the liquid, and the outlet of the air introduction tube faces the surface of the liquid in the funnel-shaped cylinder. , the container and the overflow part communicate with each other, the air introduced into the air introduction tube is blown onto the surface of the liquid from the outlet of the air introduction tube, and the generated vapor is transferred from the container to the generated vapor. It is a steam generator that is taken out as a steam generator.

Embodiment of the invention Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic system diagram for generating steam according to the present invention, and FIGS. 3 and 4 are diagrams showing the effects of the present invention.

FIG. 2 shows a system diagram in which air from the main duct 11 is supplied to the steam generator according to the present invention and the resulting steam is returned to the main duct 11. The air used in the present invention may be collected from the atmosphere. This air may be directly supplied to the steam generator, but if desired, the air may be purified through a moisture adsorption tower 12 filled with silica gel or the like, an activated carbon adsorption tower 13, and a dust removal filter 14. The air purified in this way is pumped 15
It is pumped by The compressed air passes through line 16,
The flow rate is adjusted by a mass flow meter 17. Mass flow meter 17
Since the pump 15 is normally open, an excessive flow rate flows when the pump 15 is activated, and the mass flow meter 17 is activated. Therefore, at startup, an excessive flow rate of air is blown onto the liquid surface 21, resulting in a concentration higher than the set value. in this case,
The generated steam is guided to a line 19 by a three-way valve 18 and exhausted, and after the steam concentration becomes constant, the steam is switched to a line 10 and supplied to the main duct 11. This transition time is less than 1 minute. Although it is possible to practice the invention without the mass flow meter 17, if the set steam concentration is low, it is preferable to use the mass flow meter 17 to make the steam concentration more stable.

The air whose flow rate has been adjusted by the mass flow meter enters the air introduction pipe 22 via a rotary flow meter 10 installed as necessary.

A container 24 equipped with heating means is loaded with a liquid 23 to be evaporated. The temperature of liquid 26 is set to the desired value by temperature regulator 32. The liquid 23 may be any liquid that exists as a liquid at room temperature and pressure depending on the purpose of use of the generated vapor, for example, CH3CCV3 (1,1,1-)lichloroethane), CC12-GC1□ (tetrachlorethylene).
, cH3cH(OH)CH20H (1,2-propanediol), etc. Any organic substance of any boiling point can be used. In addition, inorganic substances such as aqueous ammonia can also be used. The air introduction tube 22 is immersed in a liquid 26 in a container 24, where the temperature of the purified air is approximately equal to the temperature of the liquid 23. The air outlet 25 of the air introduction pipe is oriented perpendicularly to the liquid level 21, and the air blown from the air outlet 25 is blown onto the liquid level 21, causing the liquid 23 to evaporate. Air outlet 2
5 may be provided at an inclined angle with respect to the liquid level 21. By changing this angle, the vapor concentration can be finely adjusted.

The distance between the blower outlet 25 and the liquid level 21 may be any value. The vapor concentration can also be adjusted by adjusting this distance.

A funnel-shaped cylinder 26 is installed in the container 24, and by changing the height of the liquid level 21, the effective area for evaporation changes and the vapor concentration is adjusted. As shown in the figure, the cross-sectional area of the funnel-shaped cylinder gradually decreases downward. When the height of the liquid level 21 is lowered, the liquid surface area within the funnel-shaped cylinder 26 decreases.

The container 24 and the overflow part 27 are communicated with each other by a communication pipe 28. The liquid 2 filter stored in the tank 29 is pumped up by the pump 60 and sent to the overflow part 27, and a part of the liquid 2 filter supplied by the pump filter 0 is passed through the communication pipe 28 into the container in the same amount as the liquid evaporated. In addition to replenishing the liquid,
The remaining liquid 23 overflows the weir 61 and circulates to the tank 29. The height of the weir 61 and the height of the liquid level 21 are equal. By changing the height of the weir 61, the height of the liquid level 21 can be changed, thereby controlling the vapor concentration.

Steam generated in the upper space of the container 24 is supplied to the main gasket 11 via a line 62.

As another aspect of the present invention, the funnel-shaped cylinder 26 and the container 24'
The aj may be integrated. That is, the container 24 is shaped like a funnel-shaped cylinder, and the funnel-shaped cylinder 26 is omitted. Also in this case, the air introduction pipe 22 is immersed in the liquid 26.

FIG. 3 shows the relationship between the air flow rate and the concentration of generated vapor when 1.1.1-trichloroethane is used, comparing the device of the present invention and a conventional device (bubbling type). In the device according to the present invention, the rate of increase in the concentration of produced steam with respect to the increase in air flow rate is greater than in the conventional device. As a result, the device according to the present invention allows a wide range of product vapor concentrations to be set.

FIG. 4 shows the relationship between the saturated vapor pressure of the liquid used and the concentration of vapor produced using that liquid.

Using the apparatus of the present invention, it is possible to obtain vapor with a low concentration of 10 ppm or less. In particular, the present invention has remarkable effects on volatile liquids.

FIG. 5 is a diagram showing the influence of whether or not the funnel-shaped cylinder 26 is used on the generated steam concentration in the apparatus shown in FIG. 2. By using a funnel-shaped cylinder, lower concentration steam can be stably obtained.

Effects of the Present Invention According to the present invention, steam with less concentration fluctuation can be obtained by employing a surface spraying method.

In particular, in the present invention, since the liquid level inside the funnel-shaped cylinder is used as the effective evaporation area, the vapor concentration can be easily changed by changing the height of the liquid level. Conventional equipment requires the use of an expensive micrometer metering pump as the liquid pump;
The present invention does not require the use of such an expensive pump, resulting in an economical steam generator.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a conventional steam generator. FIG. 2 is a schematic system diagram for generating steam according to the present invention. FIG. 6 is a diagram showing the relationship between air flow rate and generated vapor concentration. FIGS. 4 and 5 are diagrams showing the relationship between the saturated vapor pressure of the liquid used and the concentration of vapor produced using the liquid. 1... Evaporation pot 6... Liquid supply line 4... Air supply line 22... Air introduction pipe 24... Container with heat transfer means 25... Air outlet 26... Funnel-shaped cylinder 27・
...Overflow section patent applicant: Shinryo Corporation (4 others) #/Figure

Claims (1)

[Claims] 1. Air, which is indirectly heat exchanged with the liquid and has approximately the same temperature as the liquid, is applied to the surface of the liquid contained in a funnel-shaped cylinder whose cross-sectional area decreases downward. A method for generating steam, comprising: spraying while maintaining a constant surface height; evaporating the liquid; and taking the generated steam out of the system. 2. A steam generator comprising a container containing a liquid to be evaporated, a funnel-shaped cylinder whose cross-sectional area decreases downward, an air introduction pipe, and an overflow part, wherein the funnel-shaped cylinder is inside the container. the air introduction tube passes through the liquid;
The outlet of the air introduction tube faces the surface of the liquid in the funnel-shaped cylinder, the container and the overflow part communicate with each other, and the air introduced into the air introduction tube is directed to the surface of the liquid in the funnel-shaped cylinder. A steam generating device, wherein the steam is sprayed onto the surface of the liquid from the discharge port and the generated steam is taken out from the container as generated steam.