JPH07174888A - Condenser - Google Patents

Abstract

PURPOSE:To prevent the corrosion of cooling pipes due to the direct hit of the high-speed steam flow without causing a pressure loss by constituting the cooling pipes in the area where at least high-speed steam flows in on the outer periphery section of a pipe bundle with double pipes having inner pipes covered by outer pipes. CONSTITUTION:This condenser has an upper main body 2 and a lower main body 3, and a pipe bundle 5 constituted of many cooling pipes 20 is stored in the lower main body 3. The cooling pipes 20 located at least on the first line of the outer periphery section of the pipe bundle 5 where the turbine exhaust steam flows in are constituted with double pipes over the whole length. An inner pipe 21 in the cooling pipe 20 is made of titanium, and the thickness is set to about 0.5mm. An outer pipe 22 made of aluminum brass covers the whole area of the inner pipe 21, and the thickness is set equal to or slightly thicker than that of the inner pipe 21. The inner pipe 21 is made of titanium, other cooling pipes are also made of titanium, thus the flow speed of the cooling sea water can be kept uniform. The inner pipes 21 are not damaged until the damage of the outer pipes 22 progresses in use for a long period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condenser attached to a steam turbine of a thermal power and nuclear power plant.

[0002]

2. Description of the Related Art In a nuclear power plant, steam generated by a steam generator is introduced into a steam turbine, a turbine impeller is rotated, and an electric output is obtained by a generator. The steam that has worked in the steam turbine is discharged from the exhaust port of the low-pressure turbine to a condenser, where it is cooled by seawater and condensed to become condensed water.

This condenser will be described with reference to the drawings.

In FIG. 3, the condenser comprises an upper main body 2 connected to the lower portion of the low pressure turbine 1 and a lower main body 3 connected to the upper main body 2, and a neck heater 4 is housed in the upper main body 2. Has been done. In order to exchange heat with the exhaust steam from the low-pressure turbine 1 in the lower body 3, a tube bundle 5 made up of a large number of cooling tubes is housed. In order to pass cooling seawater into the cooling tubes, the lower body 3 has an inlet water chamber 6a and An outlet water chamber 6b is provided. An inlet circulating water pipe 7 and an outlet circulating water pipe 8 are connected to the inlet and outlet water chambers 6a and 6b, respectively, so that cooling seawater flows through the inlet water chamber 6a, the inside of the cooling pipe, and the outlet water chamber 6b.

FIG. 4 is a view of the above condenser viewed from the low pressure turbine 1 downward. Two tube bundles 5 are arranged at right angles to the axial direction of the low-pressure turbine 1, and a neck heater 4 is arranged between the two tube bundles 5 in the tube bundle longitudinal direction. In addition, the code | symbol 9 has shown the turbine shaft. Low pressure turbine 1 in FIG.
The flow of the turbine exhaust steam in the vicinity of the joint between the upper body 2 and the upper body 2 is indicated by an arrow a.

When the turbine exhaust steam collides with the tube bundle 5 in the direction of the arrow a, minute water droplets contained in the steam collide with the cooling pipe at a high speed, and the cooling pipe may be eroded due to this repetition. As the erosion progresses, the pipe wall of the cooling pipe may be broken, and the cooling seawater inside the cooling pipe may leak into the condenser through the penetrating portion and be mixed into the condensate. As a countermeasure against this, a protective device 10 is used on the upper part of the tube bundle 5 to avoid direct hit of high-speed moisture.

An example of such a protection device 10 is shown in FIG. The protective device 10 includes a steel frame member 11 and a protective member 12.
The steam collides with the protection member 12, and the steam containing moisture loses energy due to the collision and becomes low speed, and is guided to the tube bundle 5.

FIGS. 6A and 6B show another example of the protection device 9. A protective device 13 which is smaller than that shown in FIG. 5 is provided near the outer periphery of the tube bundle 5, and the tube bundle 5 is protected by arranging it at several positions on the body plate 4 side of the condenser.

[0009]

However, when such protective devices 10 and 13 are provided, the vacuum degree of the condenser is lowered due to an increase in pressure loss. FIG. 7 specifically shows how the condenser vacuum degree decreases due to the influence of pressure loss when the installation area of this type of protection device increases. Due to this decrease in the degree of vacuum, the heat exchange performance is significantly reduced as compared with the case without the protective device.

For example, in a condenser using a titanium material for a cooling pipe, a tube having an increased thickness is used on the outer peripheral side of the tube bundle 4 which collides with moisture, while being eroded by moisture.
It is also possible to take measures to maintain a long life even if erosion progresses. However, this measure has two problems. One is that when a thick titanium tube is used, the heat transmission coefficient in heat exchange is reduced, and as a result, the condenser vacuum degree is reduced. Second, in general, the titanium tube is expensive, and it becomes more expensive when the thickness is increased, which impairs the economical efficiency.

As another method, it is conceivable to use a cooling pipe made of aluminum brass, which is thicker than the titanium pipe and has a better heat transmission coefficient, on the outer peripheral side of the tube bundle 4, but the condenser of the titanium pipe is used. To use aluminum brass tube for some parts,
There are two major problems. First, in the case of a titanium pipe, the condenser increases the flow velocity in the cooling pipe to maintain the heat exchange performance equivalent to that of the aluminum brass pipe, and the flow velocity is usually 2-3 times that of the aluminum brass pipe.

That is, if two condenser tubes of two kinds of materials are mixed in the condenser, a remarkable difference in flow velocity will occur, and the flow velocity cannot be adjusted individually, so that the heat exchange performance can be maintained. It will be difficult. Secondly, in the case of a titanium tube, in order to maintain heat exchange performance, it is necessary to keep the cleanliness of the inner surface of the tube high at all times, and cleaning with a sponge ball must be carried out frequently. On the other hand, in the aluminum brass tube, in order to prevent corrosion by seawater, it is necessary to hold a protective coating on the inner surface of the tube, and the frequency of cleaning with sponge balls is limited as much as possible. That is, the titanium tube and the aluminum brass tube have completely different cleaning frequencies, and it is not preferable to mix the cooling tubes made of two kinds of materials in the condenser.

An object of the present invention is to provide a condenser which prevents erosion from occurring in a cooling pipe which is directly hit by a high-speed steam flow, without causing pressure loss.

[0014]

DISCLOSURE OF THE INVENTION The present invention relates to a condenser having a tube bundle composed of a large number of cooling tubes in a condenser body, and cooling at least an area where high-speed steam flows in at the outer periphery of the tube bundle. It is characterized in that it is composed of a double tube in which the inner tube is covered with an outer tube that acts as a protective surface.

[0015]

[Function] The protective device used to protect the thin-walled cooling pipe made of titanium is considered to be a major factor that increases the pressure loss in the condenser. It is the main focus in eliminating the loss of heat exchange performance.

In the present invention, a cooling pipe having a combination structure of an inner pipe and an outer pipe is used without using a protective device in order to prevent erosion from water droplets on the cooling pipe. Regarding the cooling pipe consisting of this double pipe, the thickness may be increased depending on the location of the pipe bundle in consideration of the degree of damage caused by water droplets in the steam, but in the present invention, the outer pipe having the same thickness is uniformly used as the inner pipe. It is configured to cover the entire area to protect the. The outer pipe is made of, for example, an aluminum brass material having good resistance to erosion from water droplets, and the inner pipe is made of a titanium material having good corrosion resistance to cooling seawater.

The transition of the erosion amount in this cooling pipe will be described with reference to the drawings.

FIG. 2 shows the progress of erosion in the outer tube made of a corrosion-resistant aluminum brass material. The erosion of the outer tube prevents the erosion of the inner tube.

In this way, the erosion of the inner pipe can be prevented and the life of the cooling pipe can be extended. Further, since the protection device is not used, no pressure loss occurs due to the use of the protection device, so that the performance of the condenser can be prevented from being deteriorated. Regarding the outer tube, if it is an aluminum brass material, the heat transmission coefficient is superior to the titanium material, and it is possible to improve the heat exchange performance as compared with a cooling tube prepared by increasing the thickness of the titanium material to prepare for erosion. . Of course, the aluminum brass material is cheaper than the titanium material, and it can be said that it is more economical than the material in which the thickness of the titanium tube is simply increased.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1A, the basic structure of the condenser is the same as that shown in FIG. That is, the condenser includes an upper main body 2 and a lower main body 3, and the lower main body 3 accommodates a tube bundle 5 including a large number of cooling tubes. The cooling pipe 20 in at least the first row of the outer peripheral portion of the tube bundle 5 into which the turbine exhaust steam flows is formed by a double tube over the entire length. The other cooling pipe is made of titanium material. A cross section of the double pipe cooling pipe 20 is shown in FIG.

The inner pipe 21 on the inner side is made of a titanium material and is formed to have a thickness of about 0.5 mm, which is the same as the conventional one. The outer tube 22 made of an aluminum brass material covers the entire area of the inner tube 21 and is formed to have a thickness equal to or slightly larger than that of the inner tube 21.

The condenser of the embodiment has the above-mentioned structure, and when steam containing a large amount of moisture flows into the tube bundle 5, minute water droplets collide with the outer tube 22 of the cooling tube 20 at the outer peripheral portion. The outer tube 22 is an aluminum brass tube that is often used as a cooling tube material for a condenser, and erosion does not easily proceed even if it is directly hit by overlapping water drops. Since the water droplets carried by the inflowing steam directly hit the cooling pipe 20 in the first row of the tube bundle 5,
At least the first row of the tube bundle 5 is prepared for erosion by the outer tube 22 having the increased thickness. Even when arranging the portion directly hit by the water droplets with emphasis, the double pipe is used for the portion that enters the inside of the tube bundle 5 and the outer periphery where there is little possibility of being directly hit by the water droplets. The tube 20 need not be used.

Since the inner pipe 21 of this embodiment is made of titanium and the other cooling pipes are also made of titanium, the flow velocity of the cooling seawater can be kept uniform. As for the cleaning of the sponge balls, the number of applications per hour can be determined based on the titanium material. In other words, if the condenser is viewed as a whole, it can be used with the same consideration as a so-called all-titanium condenser, and no special operation method is required to be applied.

Thus, according to this embodiment, the inner tube 21 is not damaged until the outer tube 22 is damaged due to long-term use, and the life of the cooling tube can be greatly extended.

[0026]

As is apparent from the above invention, according to the present invention, the cooling pipe in the region where the restraint steam flows in the outer peripheral portion of the tube bundle is constituted by the double pipe in which the outer outer pipe covers the inner inner pipe. It is possible to prevent water droplets carried by the high-speed steam from colliding with the inner pipe under the protection of the pipes and prevent the inner pipes from being corroded by the water droplets.

Therefore, according to the present invention, it is possible to greatly extend the life of the cooling pipe without lowering the heat exchange performance of the condenser.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a condenser according to the present invention.

FIG. 2 is a diagram showing a transition of erosion amount in a cooling pipe according to the present invention.

FIG. 3 is a cross-sectional view showing a conventional condenser.

FIG. 4 is a plan view of the condenser shown in FIG.

FIG. 5 is a perspective view showing an example of a conventional protection device.

FIG. 6 is a configuration diagram showing another example of a conventional protection device.

FIG. 7 is a diagram showing a relationship between a condenser protection device and a degree of vacuum.

[Explanation of symbols]

 2 ………… Upper body 3 ………… Lower body 5 ………… Tube bundle 10, 13… Protection device 20 ………… Cooling tube 21 ………… Inner tube 22 ………… Outer tube

Claims (2)

[Claims] 1. A condenser having a tube bundle composed of a plurality of cooling tubes in a condenser main body, wherein at least a cooling tube in a region into which a high-speed steam flows at an outer peripheral portion of the tube bundle serves as a protective surface. A condenser characterized by being configured with a double pipe so that the outer pipe covers the entire inner pipe. 2. The condenser according to claim 1, wherein the outer pipe is made of an aluminum brass material, and the inner pipe is made of a titanium material together with other cooling pipes.