JP3725931B2 - Clean steam generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a clean steam generator, and more particularly to a clean steam generator that is used in the food industry, the air conditioning industry, and the like and supplies clean steam with high purity.
[0002]
[Prior art]
For example, in the food industry, in the sterilization, steaming and cooking processes in the production of beverages and processed foods, steam sterilization of the Aseptic system, steaming of sterilized packaged rice, steaming of natto, and other pressurization of cereals and beans When steaming cooking, a method of blowing boiler steam directly into food is adopted. However, the raw steam of the boiler contains a large amount of iron, chloride ions, silica, and foreign substances caused by the boiler additive. The black color changes due to the generation of the product, and the merchandise value is lost. In addition, a large amount of foreign matter is not preferable for food hygiene.
[0003]
Therefore, a clean steam generator is used as a means for effectively removing foreign substances contained in the live steam of the boiler described above. This clean steam generator blows live steam from a boiler into a liquid such as boiler water, condenses it once, re-evaporates it, and removes foreign matter (entrained entrainment) contained in this re-evaporated steam to a cyclone, etc. The steam is effectively separated and removed by a steam / water separator to obtain clean steam, which is high-purity clean steam. This clean steam is supplied into a processing apparatus installed in the next process and supplied in a predetermined manner. Used for heat treatment.
[0004]
[Problems to be solved by the invention]
By the way, in the test of condensing the clean steam obtained with the above-mentioned clean steam generator and filtering it through filter paper, it has been confirmed that the degree of contamination is greatly improved, but the electrical conductivity that is a measure of the purity of the steam is greatly improved. The current situation is that no improvement has been made, and conversely, the electrical conductivity tended to deteriorate slightly.
[0005]
Here, for example, in the case of a low pressure boiler up to 10 KG, a large amount of carbon dioxide gas is generated from the non-condensable gas contained in the boiler feed water, particularly carbon dioxide gas or carbon dioxide compound, and is contained in the boiler live steam. It has been found that the conductivity is greatly affected. That is, since the M alkali component contained in the boiler feed water is pyrolyzed to generate carbon dioxide, the amount of carbon dioxide increases and occupies the main component of the non-condensable gas. The M alkali component in the boiler feed water is NaHCO _3. Therefore, it is a component that can hardly be removed by a softener.
[0006]
On the other hand, if a large amount of non-condensable gas is contained in the live steam of the boiler supplied to the clean steam generator, the non-condensable gas is supplied to the next process together with clean steam. This clean steam generator removes the drain mist in the boiler's live steam (corresponding to the wetness), so clean steam is included in the clean steam because the absolute amount is less than the boiler's live steam. The concentration of carbon dioxide gas is relatively increased, leading to deterioration of electrical conductivity.
[0007]
In addition, when non-condensable gas containing carbon dioxide gas is supplied to the next process together with clean steam, it has also been found that this is a major heat transfer obstacle that lowers the heat transfer efficiency during cereal cooking in the next process. Yes. For example, the non-condensable gas contained in the raw steam of the low-pressure boiler is present in an amount of about 50 to 100 ppm including carbon dioxide gas. Even in such a small amount of non-condensable gas, the treatment in the next step is performed. At the time of pressure cooking by the apparatus, since the non-condensable gas about 10 to 100 times remains and accumulates, it is a serious heat transfer obstacle. When a heat transfer failure occurs in this way, there arises a problem that boiled and sterilized unevenness occurs and the commercial value is greatly reduced.
[0008]
Specifically, for example, in a processing apparatus that cooks solid food filled in a cup container, the concentration of non-condensable gas at the time of reaching a rise in temperature is about 0.4 vol%, but gas components such as air and carbon dioxide gas Since the specific gravity is larger than that of steam, it tends to accumulate at the bottom of the cup container. At the bottom of the cup container, the concentration of the non-condensable gas is two to three times, which greatly delays heat transfer. Even if the average concentration of the non-condensable gas in the processing apparatus is about 0.4 vol%, the heat transfer rate is reduced to about half by assuming that it is about 1.2 vol% at the bottom of the cup container. I guess that.
[0009]
Therefore, the present invention has been proposed in view of the above problems, and its object is to reduce the non-condensable gas in the clean steam generator, improve the electrical conductivity of the clean steam, and at the next step. It is in suppressing heat transfer failure in the process of.
[0010]
[Means for Solving the Problems]
As a technical means for achieving the above-mentioned object, the present invention is directed to injecting raw steam from a steam generation source into the liquid stored in the bottom portion to condense it once, and then condensing the condensed steam. In a clean steam generator equipped with a container that re-evaporates at an interface and separates and removes foreign substances contained in the re-evaporated steam to generate clean steam, it is present in the raw steam from the steam generating source. Forms a gas reservoir that collects the non-condensable gas contained in the vapor re-evaporated at the liquid interface on the gas-liquid interface, and discharges the non-condensable gas collected in the gas reservoir along with the excess drain. A degassing mechanism is provided.
[0011]
Specifically, in the present invention, the degassing mechanism extends from the upper part of the gas-liquid interface toward the gas-liquid interface, enters the liquid, and is directly above the gas-liquid interface with the side wall of the container. A reverse skirt-like baffle plate that forms a gas reservoir for collecting non-condensable gas contained in the raw steam from the vapor re-evaporated at the gas-liquid interface on the gas-liquid interface, and the gas A drain discharge pipe that communicates with the reservoir and discharges non-condensable gas in the gas reservoir together with excess drain from the gas-liquid interface.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a clean steam generator according to the present invention will be described with reference to FIGS. 1 is a cross-sectional view showing the overall schematic configuration of the clean steam generator, FIG. 2 is a cross-sectional view taken along the line II of FIG. 1, and FIG. 3 is an enlarged cross-sectional view of the main part of FIG.
[0013]
The clean steam generator of the embodiment shown in the figure has a live steam V ₁ from a boiler (not shown) in a liquid 2 such as boiler water stored at the bottom of a self-supporting vertically long cylindrical container _1. Is introduced from an intake 4 provided on the bottom side wall of the container 1, and the blowing unit 5 and the cylindrical baffle plate 6 attached to the tip of the introduction pipe 3 are placed in the liquid 2 at the bottom of the container. Deploy.
[0014]
The blowing unit 5 located at the tip of the introduction pipe 3 has a large number of slits 7 through which the boiler's live steam V _{1 is provided.} Is blown into liquid 2. Further, the cylindrical baffle plate 6 is attached so as to surround the blowing unit 5 described above, and the live steam V ₁ blown into the liquid 2 from the slit 7 of the blowing unit 5. The contact distance with the liquid 2 is increased.
[0015]
In addition, live steam from the boiler V ₁ Is supplied to the introduction pipe 3 while optimally controlling the pressure control valve 8 provided in the preceding stage of the introduction pipe 3 with the pressure controller 9. Moreover, the discharge pipe 10 for discharging | emitting sediments, such as an iron rust stored at the bottom of the container 1, and cleaning regularly is provided.
[0016]
In addition, in the portion corresponding to the position of the gas-liquid interface m on the side wall of the container 1, the increase in the liquid at the bottom of the container is suppressed to keep the gas-liquid interface m constant, and excess contaminants generated in the liquid 2 are caused by overflow. A drain discharge pipe 11 for discharging is provided. In addition, an inverted skirt-shaped baffle plate 12 that enters the liquid 2 while reducing the diameter from directly above the gas-liquid interface m described above is disposed. The upper end portion of the reverse skirt-like baffle plate 12 is joined to a position above the opening portion of the drain discharge pipe 11 in the side wall portion of the container 1, and the lower end portion that has entered the liquid 2 to a predetermined depth while being reduced in diameter is cylindrical. It arranges above the baffle plate 6.
[0017]
Steam V _{2 that} re-evaporates from the gas-liquid interface m between the reverse skirt-shaped baffle 12 and the side wall of the container 1. A gas reservoir 13 is formed for collecting the noncondensable gas contained in the gas immediately above the gas-liquid interface m. Further, the drain discharge pipe 11 that discharges surplus drain due to overflow communicates with the gas reservoir 13 formed by the reverse skirt-shaped baffle plate 12, and the gas reservoir together with the above-described excess drain from the drain exhaust pipe 11. The non-condensable gas collected in 13 is discharged.
[0018]
The upper end of the container 1 mentioned above has a vapor V ₂ re-evaporated from the gas-liquid interface m. A steam / water separator 14 such as a cyclone for separating and removing foreign substances contained therein is attached. On the other hand, a take-out port 15 is provided at the upper end of the side wall of the container 1, and the take-out port 15 communicates with an intake port 17 of the steam / water separator 14 through an external pipe 16. The steam separator 14 has a discharge nozzle 18 extending downward along the axial direction of the container 1, and a lower end opening thereof is disposed in the liquid 2 at the bottom of the container. In addition, an upper portion of the steam separator 14 is re-evaporated steam V _2. Clean steam V ₃ from which foreign substances contained in it are separated and removed Is provided.
[0019]
Normally, in this clean steam generator, the boiler steam V ₁ is used as follows. To Clean Steam V ₃ Is generated.
[0020]
First, live steam V ₁ from the boiler Is supplied from the introduction pipe 3 and the live steam V ₁ is supplied from the slit 7 of the blowing unit 5 at the tip of the introduction pipe 3. Is blown into liquid 2. Live steam V ₁ blown in this way Is regulated by a cylindrical baffle plate 6 on the outer periphery of the blowing unit 5, and liquid convection a occurs inside and outside the cylindrical baffle plate 6.
[0021]
Live steam V ₁ While the convection “a” of the liquid 2 is generated and becomes a large number of bubbles and rises in dispersion, the amount of heat is deprived by contact with the liquid 2 and is once condensed. This condensed steam is freshly blown live steam V ₁ And re-evaporates from the gas-liquid interface m. Vaporized vapor V ₂ Rises in the internal space of the container 1 and flows out from the outlet 15.
[0022]
Vapor V ₂ flowing out of the outlet 15 and reaching the steam separator 14 via the external pipe 16 Swirls in the steam separator 14 at high speed, and the entrainment is separated by the centrifugal force generated by the swirling, and the clean steam V ₃ is separated. And is taken out from the outlet tube 19 and supplied to the next step. On the other hand, steam V ₂ The entrainment separated from the liquid becomes droplets or a liquid film, flows down through the discharge nozzle 18 and returns to the liquid 2.
[0023]
Here, the live steam V ₁ from the boiler supplied to the clean steam generator Even if a non-condensable gas containing carbon dioxide gas is contained in this, it is quickly removed by this clean steam generator in the following manner and supplied to the processing equipment installed in the next process. It can be suppressed as much as possible.
[0024]
As mentioned above, live steam from the boiler V ₁ Is blown into the liquid 2 from the slit 7 of the blowing unit 5 at the tip of the introduction pipe 3 and is regulated by the cylindrical baffle plate 6 on the outer periphery of the blowing unit 5. Two convections a are generated.
[0025]
At this time, the convection a of the liquid 2 has the slowest flow velocity in the vicinity of the inner surface of the side wall of the container 1, so that the above-described boiler live steam V ₁ The non-condensable gas such as carbon dioxide contained in the gas becomes a gas bubble b and is easily separated by buoyancy, and is collected by the reverse skirt-shaped baffle plate 12. The gas bubbles b rise in the liquid 2 between the reverse skirt-shaped baffle plate 12 and the side wall of the container 1 and are collected in the gas reservoir 13 formed immediately above the gas-liquid interface m.
[0026]
The non-condensable gas collected in the gas reservoir 13 of the reverse skirt-shaped baffle plate 12 in this manner is discharged together with the excess drain from the drain discharge pipe 11 where the excess drain overflows.
[0027]
As described above, for example, about 50 to 100 ppm of non-condensable gas contained in the raw steam of the low-pressure boiler up to 10 KG, including carbon dioxide gas, the M alkali contained in the raw steam of the boiler. In general, the amount of carbon dioxide gas generated by pyrolysis is larger than the amount that dissolves carbon dioxide gas in the atmosphere. The solubility of the non-condensable gas, which is mainly composed of carbon dioxide, in water is ½ or less at room temperature (20 ° C.) in the case of the liquid temperature (140 ° C.) at the bottom of the container in the clean steam generator. It is falling.
[0028]
Therefore, boiler live steam V ₁ supplied to the clean steam generator. Is completely condensed by making the contact surface with the liquid 2 sufficient by the blowing unit 5, and it becomes easy to separate only the non-condensable gas containing carbon dioxide described above as gas bubbles b by buoyancy. .
[0029]
Not only non-condensable gas but also red rust-like floating substances and oil can be separated, and clean steam V ₃ The purity is further improved. Further, based on the experiment results of the present applicant, in the conventional apparatus, the electric conductivity was 5 to 12 μS / cm and the PH was 5.0 to 6.0. Stable data was obtained with a conductivity of 1 μS / cm and a pH of 6.6.
[0030]
【The invention's effect】
According to the present invention, the non-condensable gas mainly composed of carbon dioxide contained in the raw steam from the steam generation source is collected in the gas reservoir, so that it can be quickly removed by the clean steam generator. Therefore, the amount of the non-condensable gas contained in the clean steam supplied to the next process can be reduced as much as possible. As a result, the electrical conductivity of the clean steam can be greatly improved, and the purity of the clean steam can be dramatically increased, and the heat transfer efficiency in the processing apparatus in the next process can be improved, thereby preventing a heat transfer failure. The product value can be greatly improved by suppressing the occurrence of boiled and sterilized unevenness.
[Brief description of the drawings]
1 is a cross-sectional view showing an overall schematic configuration of a clean steam generator according to the present invention. FIG. 2 is a cross-sectional view taken along line II in FIG. 1. FIG. Description】
1 Container 2 Liquid 11 Drain discharge pipe 12 Reverse skirt-shaped baffle plate 13 Gas reservoir m Gas-liquid interface V ₁ Live steam from steam source V ₂ Vaporized vapor V ₃ Clean steam

Claims (2)

The raw steam from the steam generation source is blown into the liquid stored at the bottom, once condensed, and the condensed steam is re-evaporated at the gas-liquid interface of the liquid, and is contained in the re-evaporated steam In a clean steam generator equipped with a container that separates and removes foreign substances to generate clean steam, non-condensable gas contained in steam re-evaporated at the gas-liquid interface existing in the raw steam from the steam generation source A clean steam generator characterized in that a gas reservoir for collecting on the gas-liquid interface is formed, and a degassing mechanism for discharging the non-condensable gas collected in the gas reservoir together with excess drain is provided. . The degassing mechanism extends from the upper part of the gas-liquid interface toward the gas-liquid interface, enters the liquid, and exists in the raw steam from the steam source immediately above the gas-liquid interface with the side wall of the container. Then, a reverse skirt-like baffle plate that forms a gas reservoir for collecting the non-condensable gas contained in the vapor re-evaporated at the gas-liquid interface on the gas-liquid interface, and a gas in communication with the gas reservoir. The clean steam generator according to claim 1, comprising a drain discharge pipe for discharging non-condensable gas in the gas reservoir together with surplus drain from the liquid interface.

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