JP3957922B2 - Drain tank - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drain tank in a thermal power / nuclear power plant.
[0002]
[Prior art]
In general, in a thermal power / nuclear power plant, a drain tank that collects drain generated by a feed water heater or a moisture separator and separates high enthalpy drain into steam and drain is installed. FIG. 5 is a cross-sectional view showing a schematic configuration of a conventional drain tank, and a plurality of pairs (two pairs in the figure) of a low enthalpy drain inlet 2 and a high enthalpid drain inlet 3 are provided at the top of the main body 1 of the drain tank. A generated steam outlet 4 is provided in the vicinity of both ends of the top of the main body barrel 1. A drain outlet 5 is provided at the bottom of the main body barrel 1.
[0003]
On the other hand, in the main body barrel 1, a watering tray 7 having a bottom at the bottom of the low enthalpidren inlet 2 and the high enthalpidren inlet 3, above the water storage surface 6, and having a bottom at the bottom, making the drain into a liquid column or droplet. Is arranged.
[0004]
Thus, the low enthalpy drain supplied from the feed water heater or moisture separator (not shown) is guided into the drain tank body 1 from the low enthalpy drain inlet 2, and similarly, the feed water heater and moisture The high enthalpy drain supplied from the separator is introduced into the main body cylinder 1 from the high enthalpy drain inlet 3.
[0005]
Therefore, a part of the high enthalpyrene introduced into the main body 1 from the high enthalpyrene inlet 3 is flushed in the middle of falling from the high enthalpic drain inlet 3 to the water spray tray 7 and separated into drain and steam. Then, the drain which has not become steam reaches the water spray tray 7, and is mixed with the low enthalpide drain introduced into the main body 1 from the low enthalpy drain inlet 2 in the water spray tray 7. And discharged below the sprinkling tray 7. The drain discharged below the sprinkling tray 7 generates steam until it becomes saturated water while falling to the water storage surface 6, and is separated into steam and drain. The drain is stored in the main body trunk 1. . On the other hand, non-condensable gases such as steam and air separated from the drain as described above are discharged from the generated steam outlet 4.
[0006]
[Problems to be solved by the invention]
In recent power plants, the concentration of dissolved oxygen contained in feed water has become a problem, and it is known that stress corrosion cracking occurs in equipment due to the high concentration of dissolved oxygen.
[0007]
By the way, since the drain produced | generated with the drain tank is collect | recovered by feed water, it becomes possible to reduce the dissolved oxygen concentration in feed water by reducing the dissolved oxygen concentration in the drain of a drain tank.
[0008]
However, in the conventional drain tank, the high enthalpyrene is flushed and the purpose of separating steam and drain is achieved, but there is a problem that the dissolved oxygen in the low enthalpyrene is not sufficiently degassed.
[0009]
In view of the above, an object of the present invention is to obtain a drain tank having a high effect of removing dissolved oxygen.
[0010]
[Means for Solving the Problems]
The present invention according to claim 1 is a drain tank in which a drain inlet and a generated steam outlet are provided in an upper portion of a drain tank main body, and a water spray tray is provided in the drain tank main body below the drain inlet. A partition wall is provided to cut off the communication between the drain inlet and the generated steam outlet adjacent to each other from at least one edge of the spray tray, and the upper space of the spray tray and the drain tank main body are disposed only on the opposite side of the generated steam outlet. An opening communicating with the inside is formed.
[0011]
The invention according to claim 2 is that in the invention according to claim 1, the watering tray is a box-shaped body having a side wall constituting the partition wall and having an opening only on the side wall opposite to the generated steam outlet. Features.
[0012]
Further, the invention according to claim 3 is the invention according to claim 1, wherein the amount of dissolved oxygen in the drain introduced into the drain tank and the amount of steam generated from the drain are equalized at each drain inlet so as to be equal for each watering tray. It is characterized by appropriately combining the introduced steam.
[0013]
According to a fourth aspect of the present invention, in any one of the first to third aspects, the porous plate is disposed above the water storage surface in the drain tank main body.
[0014]
Further, the invention according to claim 5 is the invention according to any one of claims 1 to 3, characterized in that a porous plate is disposed in the water storage in the drain tank main body.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the present invention will be described below with reference to FIGS. In the figure, the same parts as those in FIG.
[0016]
FIG. 1 is a view showing a first embodiment of the present invention. A watering tray 8 disposed below a low enthalpyrene inlet 2 and a high enthalpyrene inlet 3 has a drain at one end edge thereof. A partition wall 8a reaching the upper inner wall surface of the tank body 1 is integrally provided upright. Then, the communication between the high enthalpydrene inlet 3 and the generated steam outlet 4 adjacent to each other is cut off by the partition wall 8a. On the other hand, an opening 9 that communicates the upper space of the water spray tray 8 and the inside of the drain tank main body 1 is formed only on the side opposite to the generated steam outlet 4.
[0017]
Thus, part of the drain introduced from the high enthalpid drain inlet 3 is separated from the drain and becomes steam before dropping to the water spray tray 8. The generated steam flows from the opening 9 formed only on the side opposite to the generated steam outlet to the lower part of the watering tray 8 and further passes through the lower part of the watering tray 8 to the generated steam outlet 4 as indicated by the solid line arrow. . On the other hand, high enthalpyrene, which has not become steam, is received by the watering tray 8.
[0018]
While the low enthalpyrene introduced from the low enthalpyrene inlet 2 falls to the sprinkling tray 8, it is heated and degassed by the steam generated by the high enthalpyrene, and then received by the sprinkling tray 8. Mix with the drain that did not. The mixed drain falls from the perforation of the water spray tray 8 and is further heated and deaerated by the steam generated from the high enthalpy drain passing through the lower portion of the water spray tray 8 as described above until reaching the water storage surface.
[0019]
Therefore, the steam generated in the watering tray always passes through the lower part of the watering tray 8 and is heated in contact with the drain having dissolved oxygen, thereby effectively removing the dissolved oxygen in the drain. That is, the solubility of oxygen in the drain is proportional to the oxygen gas partial pressure according to Henry's law, and the Henry's constant, which is a proportionality constant, becomes smaller as the drain temperature is higher at a drain temperature of about 100 ° C. or higher. Becomes difficult to dissolve in the drain. Therefore, the drain can be effectively degassed by heating the drain and increasing the temperature of the drain.
[0020]
By the way, in the said embodiment, although what provided the partition wall 8a in the one side edge part of the water spray tray 8 was shown, while a water spray tray is made into a box-shaped body and a partition wall is comprised by each side wall, generated steam You may form the opening part 9 in the opposite side to an exit.
[0021]
In addition, if the amount of dissolved oxygen in the drain and the amount of steam flushed from the drain are uneven for each watering tray, sufficient steam is supplied in one watering tray and the drain is heated and degassed sufficiently. In such a watering tray, sufficient steam for degassing the dissolved oxygen in the drain is not supplied, the heating of the drain becomes insufficient, and the dissolved oxygen in the drain may not be degassed well.
[0022]
FIG. 2 is a view showing a second embodiment of the present invention in which the dissolved oxygen in the drain can be uniformly degassed, and the drain inlet 10 has a dissolved oxygen in the drain for each water spray tray 8. The amount and the generated steam amount are arranged to be equal.
[0023]
That is, the generation ratios of the steam introduced into the drain inlets 10a and 10b and the drain inlets 10c and 10d are almost the same in consideration of the dissolved oxygen amount and the generated steam amount calculated in advance in the design stage. It is trying to become. For example, when the generated steam amount of the steam introduced into the drain inlet 10a is 1 and the dissolved oxygen amount is 2, the steam with the generated steam amount of 2 introduced into the drain inlet 10b and the dissolved oxygen amount of 1 is introduced. Therefore, when each steam is mixed in the water spray tray 8, the generated steam amount is 3, and the dissolved oxygen amount is 3, so that both are equal. Similarly, the drain inlets 10c and 10d are combined in consideration of the amount of steam generated and the amount of dissolved oxygen.
[0024]
Thus, by supplying uniformly the steam necessary for degassing the dissolved oxygen in the drain for each water spray tray 8, the dissolved oxygen in the drain can be effectively degassed.
[0025]
FIG. 3 is a diagram showing a third embodiment of the present invention, in which a perforated plate 11 such as a perforated plate, a net-like flat plate, or a lattice-like plate is provided between the watering tray 8 and the water storage surface 6. Is arranged. Other points are the same as those of the embodiment shown in FIG.
[0026]
Therefore, in this embodiment, the drain that has fallen from the water spray tray 8 is received once by the perforated plate 11 above the water storage surface 6 and does not fall directly on the water storage surface. Therefore, entrainment of bubbles on the water storage surface is reduced, and oxygen contained in the bubbles is prevented from being dissolved in the water storage.
[0027]
By the way, when bubbles are involved in the drain on the water storage surface, the pressure in the bubbles increases due to the water pressure due to the depth from the water storage surface, and the partial pressure of oxygen in the bubbles increases. As a result, according to Henry's law, the solubility of oxygen in the drain increases, and the dissolved oxygen concentration in the storage drain increases. Further, when the entrainment of bubbles becomes deep, the pressure in the bubbles increases, so that the vapor in the bubbles is condensed and the bubbles become small. As the bubbles become smaller, the pressure inside the bubbles increases due to the surface tension, and more oxygen is dissolved in the water storage drain.
[0028]
However, in this embodiment, since the porous plate 11 is provided as described above, the entrainment of bubbles in the drain on the water storage surface is reduced, the oxygen is prevented from being dissolved in the water storage drain, and deaerated. It is possible to prevent oxygen from dissolving in the stored water again.
[0029]
FIG. 4 is a view showing a fourth embodiment of the present invention, in which a perforated plate 11 is disposed in the water reservoir. In this case as well, the condensate that has fallen directly from the sprinkling tray 8 into the water storage can be reduced by the perforated plate 11 provided in the water storage, and the oxygen contained in the air bubbles can be dissolved into the water storage. Is prevented.
[0030]
【The invention's effect】
Since the present invention is configured as described above, the steam separated from the drain at the sprinkling tray is not directly discharged from the generated steam outlet, and the generated steam always comes into contact with the drain falling from the sprinkling tray. Can be effectively degassed. Further, in the case where the drain inlet is disposed so that the dissolved oxygen amount and the generated steam amount are equal for each watering tray, the dissolved oxygen in the drain can be more effectively degassed. Further, in the case where a blocking plate is provided on the water storage surface or in the water storage, the entrainment of bubbles is reduced and the deaerated oxygen is prevented from being dissolved again in the water storage.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of a drain tank according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing a schematic configuration of a drain tank according to a second embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a schematic configuration of a third embodiment of a drain tank according to the present invention.
FIG. 4 is a sectional view showing a schematic configuration of a fourth embodiment of a drain tank according to the present invention.
FIG. 5 is a sectional view showing a schematic configuration of a conventional drain tank.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Body trunk | drum 2 Low enthalpidren inlet 3 High enthalpidren inlet 4 Generated steam outlet 5 Drain outlet 6 Water storage surface 7, 8 Sprinkling tray 8a Partition wall 9 Opening part 10,10a, 10b, 10c, 10d Drain inlet 11 Perforated plate

Claims (5)

In the drain tank provided with a drain inlet and a generated steam outlet in the upper part of the drain tank main body, and provided with a watering tray below the drain inlet in the drain tank main body, it is mutually connected from at least one end edge of the watering tray. A partition wall that cuts off the communication between the adjacent drain inlet and the generated steam outlet was erected, and an opening was formed on the opposite side of the generated steam outlet to connect the upper space of the watering tray and the inside of the drain tank body. A drain tank characterized by that. 2. The drain tank according to claim 1, wherein the water spray tray is a box-shaped body having side walls constituting partition walls and having openings only on the side walls opposite to the generated steam outlet. The introduced steam is appropriately combined at each drain inlet so that the amount of dissolved oxygen in the drain introduced into the drain tank and the amount of steam generated from the drain are equalized for each watering tray. 2. The drain tank according to 2. The drain tank according to any one of claims 1 to 3, wherein a perforated plate is disposed above the water storage surface in the drain tank main body. The drain tank according to any one of claims 1 to 3, wherein a perforated plate is disposed in the water storage in the drain tank main body.

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