JPH10246401A - Clean steam generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clean steam generating device, compacted in constitution as a whole and capable of effecting heat exchange efficiently. SOLUTION: A device for generating the steam of clean water employing general steam as heat medium for heating, is constituted of a multitude of small heat transfer tubes 16 for clean water, which are arranged in a boiler 10 for an evaporator 1 in up-and-down direction, and pipes 17, 18 for introducing and discharging heat medium for heating into and from the circumference of the heat transfer tubes 16. Clean water, heated in the heat transfer tubes 16, is made to ascend together with generated steam, then, is guided to the lower part of a lower tube plate from the upper part of an upper tube plate 14 through a water descending pipe 22, provided at the central part of the heat transfer tubes 16, and, thus, the clean water is circulated and heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clean steam generator for generating clean and high-quality steam using general factory steam or the like as a heating medium for heating.

[0002]

2. Description of the Related Art Various technical fields such as food, medicine,
In factories and laboratories of pharmaceuticals, semiconductors, chemistry, etc., clean steam free of impurities is often required.
Usually, in boilers installed in general factories, etc., the water supply itself is not always sufficiently clean, and various chemicals etc. may be mixed in water to protect cans, etc. If it is brought into direct contact with food or medical equipment or used to humidify various working spaces, it will contaminate food and various equipment, and contaminate clean rooms and other working environments.

To cope with such a problem, a clean steam generator for generating clean and high-quality steam using general factory steam or the like as a heating source has been conventionally used. This clean steam generator basically has the same configuration as that shown in FIG. Referring to FIG. 1, the outline of the structure will be described. The clean steam generator includes an evaporator 1 for heating and evaporating clean water such as pure water using general factory steam as a heating medium for heating, and an evaporator for the evaporator. 1 is provided with a preheater 2 for preheating water (clean water) supplied to the evaporator 1 with a heat medium discharged after heating the clean water.
As the evaporator 1, those having various configurations are known. For example, in a can into which factory steam is introduced, a large number of thin tubes which are attached to the upper and lower tube sheets at both ends and directed vertically. A heat transfer tube having a diameter is disposed, the heating medium for heating is introduced around the heat transfer tube, the clean water heated through the heat transfer tube is raised together with the generated steam, and the clean water discharged upward is discharged. A system in which feed water is circulated and heated by means such as guiding the feed water to a lower portion of the evaporator through a downcomer provided outside the evaporator 1 is effective for efficiently heating and evaporating the feed water.

However, in the clean steam generator having the above-described structure, a downcomer disposed outside the evaporator is
Usually, it is necessary to have a cross-sectional area of several tens% of the total cross-sectional area of the small-diameter heat transfer tube, and therefore, it is necessary to arrange a relatively thick downcomer in parallel with the evaporator 1, and this leads to an increase in efficiency. This has led to a reduction in the size and complexity of the apparatus. Also, when providing a water level detector for detecting the water level of the feed water, it is necessary to provide the water level detector between the upper and lower ends of the evaporator 1 or between the upper part of the evaporator and the downcomer, which complicates the structure. There is also a problem that the device becomes complicated due to the presence of a large number of tubes.

[0005]

The technical problem of the present invention is basically to provide a clean steam generator having a compact structure as a whole and capable of efficiently exchanging heat. . A more specific technical object of the present invention is to provide a clean steam having a simple structure and reduced thermal loss by housing a downcomer in the evaporator without juxtaposing the evaporator outside. A generator is provided. It is another technical object of the present invention to provide a clean steam generator capable of further activating thermosiphon action by using low-temperature clean water supplied into a can using the downcomer. Another technical object of the present invention is to provide a clean steam generator in which the size and complexity of the apparatus for mounting the water level detector on the evaporator are suppressed. Another technical object of the present invention is to provide a clean steam generator in which heat exchange is performed more efficiently by a preheater.

[0006]

According to a first aspect of the present invention, there is provided a clean steam generating apparatus for generating clean water vapor using general steam in a can of an evaporator as a heating medium for heating. A steam generator, comprising: a plurality of vertically-extending small-diameter heat transfer tubes, both ends of which are attached to upper and lower tube sheets, disposed in the can, and the heating medium for heating is provided around the heat transfer tubes. In addition to connecting the pipes for introducing and discharging the heat, the clean water heated through the heat transfer pipes is raised together with the generated steam, and the clean water led out to the space above the upper tube sheet is discharged to the lower space of the lower tube sheet by the downcomer. In which the clean water is circulated and heated to take out clean steam from the space above the upper tube sheet, wherein the downcomer is attached between the heat transfer tubes in the can and between the upper and lower tube sheets. Is what you do.

In a preferred embodiment of the above-mentioned clean steam generator, a water supply pipe for supplying clean water into the can is opened at the upper end of the downcomer or communicates with the space above the upper tube sheet outside the can. A water level detector is mounted between the water level detection pipe and the water level detection pipe penetrating the can wall and communicating with the downcomer. The above-mentioned clean steam generator includes a preheater for introducing a heating medium for heating the clean water introduced around the heat transfer tube and supplying the clean water heated thereby into the can of the evaporator. It is desirable to have a water supply pipe.

[0008] In the clean steam generator having the above configuration, the clean water preheated by the preheater is preferably:
The water is supplied into the evaporator can through a water supply pipe opened at the upper end of the downcomer, and general factory steam or the like is introduced around the heat transfer pipe as a heating medium for heating clean water. The supplied clean water descends down the downcomer because the specific gravity is higher than the clean water already heated in the can, while the clean water in a large number of vertically oriented heat transfer tubes is removed from the outside thereof. Heated by the heat medium, the specific gravity decreases and rises in the pipe together with the generated steam, and therefore, the clean water in the can is circulated and heated by the thermosiphon action.

In this case, the supply of the low-temperature clean water to the upper end of the downcomer by the water supply pipe is very effective for generating a downflow in the downcomer and activating the thermosiphon action. By disposing the downcomer in the can of the evaporator, the heat loss is reduced by a simple structure without covering with heat insulating material as in the case of disposing it outside the can, Moreover, the configuration of the evaporator can be simplified without having a downcomer arranged outside the evaporator.

[0010] In the case of heating from the outside of the heat transfer tube with the above-mentioned factory steam or the like, a very high heat transfer property is obtained by condensation heat transfer, while inside the heat transfer tube, clean water heated by the heating heat medium is used. Is rapidly raised together with the generated steam, so that the heat transfer property on the inner surface of the heat transfer tube is enhanced, and the feedwater and circulating water flowing down the downcomer are also heated in the can within the range that does not impair the thermosiphon action, so that the efficiency is improved. Heat exchange can be performed. Also,
The heating heat medium introduced around the heat transfer tube in the evaporator and used for heating the clean water is supplied to the preheater as steam by lowering the pressure, where it is used for preheating the clean water flowing in the tube. Is done. The evaporator is supplied with the heated clean water through a water supply pipe.

In the above evaporator, in order to detect the water level of the clean water, it is customary to provide a water level detector between the upper and lower ends of the evaporator. The evaporator has a longer space to secure the mounting space for the detector tube for mounting at the upper and lower ends of the evaporator, and the detector tubes that make up the water level detector are arranged side by side over almost the entire length of the evaporator. However, as described above, a water level detector is provided between the water level detection pipe communicated with the space above the upper tube sheet and the water level detection pipe penetrating the can wall and communicating with the downcomer. When installed, it is not necessary to lengthen the evaporator can, and the water level detector can be mounted only on the necessary parts.This simplifies the structure and at the same time avoids complication of the device due to the presence of the long water level detector. Overall compact evaporator It becomes possible to.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a clean steam generator according to the present invention. This clean steam generator is
Basically, it is for generating steam of purified water by removing impurities with pure water and various other filters, using general factory steam as a heating medium for heating in the evaporator can. is there. FIG. 1 shows an outline of the entire apparatus, in which an evaporator 1 for heating and evaporating clean water such as pure water using factory steam or the like as a heating medium for heating, and after heating the clean water in the evaporator 1. A preheater 2 for preheating water (clean water) supplied to the evaporator 1 by the discharged heat medium.

FIG. 2 and FIG. 3 show an example of the structure of the evaporator 1. In the evaporator 1, a can 10 into which factory steam is introduced is constituted by an upper body plate 11, a body plate 12, and a lower head plate 13, and upper and lower tube sheets 14, 15 are provided in a can formed by the body plate 12. A large number of small-diameter heat transfer tubes 16 are disposed at both ends of the can 10 and arranged in the vertical direction, and the inside of the can 10 is partitioned by the tube plates 14 and 15, and the body plate 12 is provided with a steam source such as a boiler. A tube 17 for connecting and introducing the heating medium for heating around the heat transfer tube 16 is connected to an upper portion thereof, and a tube 1 for discharging the heat medium after heating the heat transfer tube 16.
8 is connected to the lower part.

The large number of heat transfer tubes 16 having both ends attached to the upper and lower tube sheets 14 and 15 form a space 20 above the upper tube sheet 14 in the upper body plate 11 and a lower tube sheet 15 in the lower end plate 13. The upper and lower spaces 2 are located between the tube plates 14 and 15 at the upper and lower portions thereof at substantially the center of a large number of heat transfer tubes 16.
A downcomer 22 for connecting 0 and 21 is attached. And the water supply pipe 24 for supplying clean water into the can 10 is
It is attached to the upper body plate 11 and is opened at the upper end of the downcomer 22. Further, a demister 25 is provided in the upper body plate 11, and a steam extraction pipe 26 for taking out clean steam from which water droplets have been separated by the demister 25 is connected to the upper body plate 11. Is connected to a blow water discharge pipe 27.

The water level in the evaporator 1 is usually located just above the upper tube sheet 14, but in order to detect the water level, a water level detection pipe 31 communicated with the space 20 above the upper tube sheet 14 is used. And a water level detection pipe 32 penetrating through the body plate 12 and communicating with the downcomer pipe 22.
A water level detector 33 is attached outside the can 10 between 1 and 32. In addition, in FIG.
And 34b indicate water level switches for detecting upper and lower limits of a normal water level, and 35a and 35b indicate water level switches for detecting abnormal upper and lower limits of water level.

Further, in the illustrated embodiment, the downcomer 22 is provided in a number of heat transfer tubes 16 near the center of the body plate 12, but it is easy to connect with the water level detecting tubes 31 and 32. In order to suppress the generation of useless space in the can 10 due to the installation of the water level connecting pipes 31 and 32, the downcomer 2
2 from the center in the body plate 12 (the water level detection tube 3
1, 32). In FIG. 1, reference numeral 36 denotes a pressure regulating valve.

In the evaporator 1 having the above structure, the preheater 2
Is supplied into the can 10 through a water supply pipe 24 opened at the upper end of the downcomer 22, and factory steam or the like is supplied from a steam source through a pipe 17 as a heat transfer medium for heating the clean water. Is introduced around. Since the supplied clean water has a higher specific gravity than the clean water already heated in the can 10, the clean water descends down the downcomer 22 to reach the space 21 below the lower tube sheet 15, and on the other hand, a large number of The clean water in the heat transfer tube 16 is heated by the heat medium from the outside thereof, has a low specific gravity, rises in the tube 16 together with the generated steam, and is led to the space 20 above the upper tube sheet 14. Therefore, the clean water in the can rises in the heat transfer tube 16 and the downcomer 2
2, the clean water in the can 10 is circulated and heated by the action of thermosiphon, and clean steam flows from the space 20 above the upper tube sheet 14 through the demister 25 and the steam discharge pipe 26. Be taken out.

In this case, the supply of the low-temperature clean water to the upper end of the downcomer 22 by the water supply pipe 24 is very effective for generating a downflow in the downcomer 22 to activate the thermosiphon action. In addition, by disposing the downcomer pipe 22 in the can 10 of the evaporator 1, unlike the case of disposing it outside the can, the downcomer 22 is not covered with a heat insulating material and has a simple structure. Heat loss is reduced and the can 10
Although the diameter of the evaporator 1 is slightly increased, the configuration of the evaporator 1 can be simplified without the downcomer 22 being arranged side by side. In particular, the evaporator 1 having the above-described configuration
In this case, it is necessary to use a relatively thick downcomer 22 having a cross-sectional area of about 40% of the total cross-sectional area of the small-diameter heat transfer tube 16. However, if it is accommodated in the can 10, the diameter can be increased slightly.

In the case of heating with heat from the outside of the heat transfer tube 16 using factory steam, a very high heat transfer property is obtained. On the other hand, inside the heat transfer tube 16, the clean water heated by the heating heat medium is removed. Since the temperature of the heat is increased rapidly with the generated steam, the speed of the clean water flowing inside the heat transfer tube is high with respect to the inner surface of the heat transfer tube. Therefore, the heat transfer on the inner and outer surfaces of the heat transfer tube 16 is enhanced. Since the circulating water is also heated in the can within a range that does not impair the thermosiphon effect, efficient heat exchange can be performed.

In the evaporator 1, if a water level detector 33 is provided between the upper and lower ends of the evaporator 1 in order to detect the water level of the clean water, a space for mounting a water level detection pipe for mounting the water level detector 33 is provided. Since it is necessary to secure the evaporator 1 at both upper and lower ends, the evaporator 1 becomes longer, and the pipes constituting the water level detector are arranged side by side over substantially the entire length of the evaporator 1, which is an obstacle to compactness. However, as described above, between the water level detection pipe 31 communicated with the space 20 above the upper tube sheet 11 and the water level detection pipe 32 penetrating the body plate 12 and communicating with the downcomer pipe 22. If the water level detector 33 is attached, the can 10 of the evaporator 1 does not need to be lengthened, and the water level detector 33 can be attached only to a necessary portion. Therefore, the structure is simplified and the long water level detector is used. Of equipment due to presence of Avoid, it is possible to entirely compact evaporator 1.

FIG. 4 shows an example of the structure of a preheater 2 for preheating feedwater supplied to the evaporator 1. This preheater 2
As can be seen from FIG. 1, a heating heat medium introduced around the heat transfer tube in the evaporator 1 and used for heating the clean water is introduced, thereby heating the clean water and supplying water to the evaporator 1. Is what you do. More specifically, in this preheater 2, a spiral tube 41 is housed in a vessel 40, an inflow pipe 43 at one end thereof is connected to a supply source of clean water, and the other end is connected. Water supply pipe 2 of the evaporator 1
4 and a preheating water supply pipe 44 connected to the
Is connected to an inflow pipe 45 for heating the heat transfer pipe 16 of the evaporator 1 and introducing the heat medium discharged from the pipe 18, and also heats and condenses the clean water in the spiral tube 41. A discharge pipe 46 for discharging condensed water and the like is connected.

In the preheater 2, clean water is supplied from a water supply source to the tube 41, and the inside of the vessel 40 is set to a pressure close to the atmospheric pressure. The heat medium supplied to the heating of the clean water is reduced in pressure to produce the steam again as steam.
Since the water is introduced into the inside of the tube 41, the preheating of the clean water flowing in the tube 41 is efficiently performed. The clean water heated by the preheater 2 is supplied to the water supply pipe 24 of the evaporator 1 through the preheat water supply pipe 44.

[0023]

According to the present invention described in detail above, unlike a conventional clean steam generator, a downcomer is not provided alongside the evaporator, but is accommodated in the evaporator. Not only can heat loss be reduced with a simple structure, but also the thermosiphon action can be further activated by low-temperature clean water supplied into the can using the downcomer, It is possible to obtain a clean steam generator that suppresses an increase in the size and complexity of the installation of the water level detector, thereby resulting in a compact overall configuration and efficient heat exchange. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of an overall configuration of an embodiment of a clean steam generator according to the present invention.

FIG. 2 is a vertical sectional view of the evaporator in the embodiment.

FIG. 3 is a cross-sectional view of the evaporator in the embodiment.

FIG. 4 is a longitudinal sectional view of a preheater in the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 evaporator 2 preheater 10 can 14 upper tube sheet 15 lower tube sheet 16 heat transfer tube 17, 18 tube 20, 21 space 22 downcomer tube 24 water supply tube 25 demister 26 steam extraction tube 31, 32 water level detection tube 33 water level detector

Claims (4)

[Claims] 1. A clean steam generator for generating steam of clean water in a can of an evaporator using general steam as a heat medium for heating, wherein both ends of upper and lower tube sheets are mounted in the can. A large number of small-diameter heat transfer tubes oriented in the vertical direction are provided, and the pipes for introducing and discharging the heating heat medium are communicated around the heat transfer tubes, and the heated cleanliness is heated through the heat transfer tubes. The water is raised together with the generated steam, and the clean water led to the space above the upper tube sheet is guided to the lower space of the lower tube sheet by the downcomer to circulate and heat the clean water. Wherein the downcomer is mounted between the upper and lower tube plates between the heat transfer tubes in the can. 2. The clean steam generator according to claim 1, wherein a water supply pipe for supplying clean water into the can is opened at an upper end of the downcomer. 3. The clean steam generator according to claim 1, wherein the water level detection pipe communicates with the space above the upper tube sheet outside the can, and communicates with the downcomer through the can wall. A clean steam generator, wherein a water level detector is mounted between the water level detection pipe and the water level detector. 4. A clean steam generator according to claim 1, further comprising a preheater for introducing a heating medium for heating the clean water introduced around the heat transfer tube. And a water supply pipe for supplying clean water heated thereby into the can of the evaporator.