KR20020064043A - Method for determination of Tube Leakage of Condenser and Heat Exchanger - Google Patents

Abstract

PURPOSE: A method for checking leakage portion is provided to check the leakage portion in an accurate and rapid manner regardless of the thickness of tube and foreign substances. CONSTITUTION: A method comprises a first step of depositing a foam(20) to both sides of a plurality of tube sheets of a condenser or heat exchanger, through a foam depositing device(10); and a second step of checking the portion where the deposit foam is depressed, by applying vacuum into the condenser. The foam depositing device has a flexible pipe(40) arranged at a foam bomb(30) which contains the foam, and an extended pipe(50) is connected to the flexible pipe. The extended pipe has a foam deposition adaptor(60) arranged at an end of the extended pipe, and the foam deposition adaptor is formed into a dual structure including an inner pipe(61) having holes(62) for uniformly discharging foam, and an outer pipe(63) for discharging foam through an open surface(64).

Description

{Method for determination of Tube Leakage of Condenser and Heat Exchanger}

The present invention relates to a method for checking the leaking part of the condenser and the heat exchanger tube, and a foam developed by using a foam coating device on both sides of a plurality of tube sheets, such as the condenser and the heat exchanger, or a device menhole or a gasket, Applying a vacuum (negative pressure) to the naked eye to determine the state of the applied foam to find the leaking part, and when the foam is applied using a foam coating device, the foam has good adhesion to the tube and liquid Due to the low self-aggregation, the vertical tube hole can be easily sealed, the specific gravity of the bubble itself is small, and the bubble blocking the tube hole is easily moved with a small pressure difference due to the pinhole. When the vacuum is applied to the condenser, the foam applied to the leaking site becomes indented so that the leak tube can be easily identified.

The condenser using seawater as cooling water for heat exchange of nuclear and thermal power plants flows through a plurality of tubes inside the main body, and the cooling seawater flows to the condenser main body. If the water is leaked into the condenser due to corrosion or impact during operation, the seawater leaks into the condenser and flows into the power generation system, and the boiler and turbine are severely corroded by the condensate. As it stops, it must be quickly found and blocked or replaced.

In power plants, the condenser is an important facility that greatly affects not only efficiency and power, but also stable operation of the power plant. If cooling seawater leakage occurs in multiple engines, the output must be reduced, or in severe cases, power generation must be stopped and repaired.

Therefore, in the power plant, a lot of efforts have been made to maintain the performance of the condenser and to prevent the leakage of the pipe, and it is important to check the leak quickly in the case of the condenser.

Existing methods of checking the leaking part of the condenser include a method of using a PVC film or window paper, a method of using a soap bubble, an eddy (Eddy current test) method, a method of using a manometer, and the like. The problem is as follows.

1) How to use PVC film or window paper.

The most frequently used method is to attach a thin film to the inner surface of a plurality of pipes, and to check the bleeding or tearing of the film by checking the unevenness or tearing of the air through a small hole. This method is poor in adhesiveness of films and difficult to inspect fine leaks due to materials such as PVC protection tube inserted into the tube inlet to prevent tube erosion and marine organisms attached to the condenser tube sheet. Even if the method is implemented, it is difficult to respond quickly and accurately in case of leakage, such as a lot of re-inspection after restarting.

2) How to use soap bubbles

Soap bubbles naturally defoam within a short time and cannot be used when the temperature in the water box is about 40 to 60oC.

3) ECT (Eddy current test) method

Pinholes less than 0.2 mm in area are difficult to detect, and deeper probes of less than 1/4 ”are impossible, and they are difficult to apply to ferromagnetic materials.

In addition, the sensitivity of the tube (limited to 2.77mm-19.05mm in case of magnetic deflection and current inspection method) or sediment is limited, and the measuring equipment is expensive, and time and manpower are required. (Only 15 days per 300 persons)

In addition, when local corrosion occurs in the condenser tube, there is a fear that it will be mistaken as a small hole.

4) How to use a manometer

Since one tube can be tested at a time, it can not be applied in practice because of time and manpower consumption.

Current methods as described above have a problem in that workability is poor, it is difficult to find a fine leak point, and there is no accurate method for finding a leak point of the expansion part between the tube sheet and the tube and the leak point of the condenser case.

The present invention has been made in view of the above-mentioned problems, and it is possible to find the leaking part of a very small hole accurately and quickly regardless of the tube thickness or foreign matter attachment, so as to improve the workability to self weight rather than liquid. It is a coating device that can carry very fine and hard foam film such as shaving foam with little cohesion effect by applying it to the menhole gasket on both sides of the tube sheet or on the plate surface of plural engines, and apply negative pressure (vacuum) to the inside of the condenser, As a method of finding, the above method is an accurate way to find a hole with a diameter of 0.1mm or less, and a single unit leak test is about 30 minutes to 2 hours. The purpose is to find the tube extension and the leak point of the case.

1 is a block diagram showing a foam coating device of the present invention.

2 is a block diagram showing a use state of the present invention.

♣ Explanation of symbols for main part of drawing ♣

10: foam coating device 20: foam

30: bubble bomb 40: expansion tube

50: extension tube 60: foam coating adapter

61: inner tube 62: hole

63: outer tube 64: open surface

70: tube surface

In the present invention for achieving the above object in the leak check method of the condenser tube using seawater as cooling water for the purpose of heat exchange of nuclear power plants or thermal power plants, as shown in Figure 1 to 3,

Applying the foam (20) developed by using the foam coating device (10) on both sides of the tube sheet and the device menhole or gasket, such as the condenser and the heat exchanger, by applying a vacuum (negative pressure) to the interior of the condenser It was configured to look for the leaked state by visually confirming the state of the bubble 20 is collapsed.

Here, the foam coating device 10 forms a flexible tube 40 on one side of the foam bomb (bomb) 30, which is a pressure vessel containing the foam 20, the extension tube 50 to the expansion tube 40 Forming a foam coating adapter 60 at the end of the extension pipe 50, the foam coating adapter 60 is formed of a double tube, the inner tube 61 is formed a plurality of holes 62 on the back In order to make the foam 20 come out evenly, the outer tube 63 may be configured such that the front end is opened by about 2 cm so that the foam 20 is discharged through the open surface 64.

Referring to the use state of the present invention as described above are as follows.

First, since the foam is used in a closed condenser chamber, the liquefied gas added as a blowing agent is made non-combustible, and the foam applied to the tube can be uniformed even with a foam coating adapter or the like. It is important to select the drug because it should maintain firmness and viscosity to ensure good adhesion to the surface. The storage of the foam liquid can be made in a general environment, assuming urgent cases and the foam liquid can be applied to the foam with a portable foam coating device.

Foaming drugs that meet the above conditions were selected, including foaming properties, ratios of chemicals, types of added liquefied gas, pressure loss in the process of foaming, and nozzle shape. The main component of the foam drug is LAS (Linear Alkylbenzen Sulfonate), which is used as a shampoo, as a surfactant. It is made of linear alkylbenzene, and gelatin is used as a drug to form a solid bubble, and liquefied carbonic acid is used as a propellant. The composition of

5-20% of surfactants (alkyl benzene linear as LAS for shampoo)

Methylcellulose 0.1%-2.0%

Benzoic acid 0.01%-0.5%

Glycerin 2.5-5.0%

Gelatin 1.0-10.0%

55-75% of water

Other (liquefied carbon dioxide).

Referring to the embodiment for confirming the leakage site using the foam formed as described above are as follows.

Remove foreign substances such as shells on the surface of the condenser and heat exchanger.

At this time, it is applicable even if some foreign matter such as seaweed remains. Wash the coated surface with water such as industrial water.

If there is a large amount of residual water in the tube, bubbles will flow down, and depending on the conditions, it is dried by wind or the like to remove the residual water.

As described above, when the upper valve (not shown) of the foam cylinder 30, which is a pressure vessel containing foam 20, is opened on the tube surface 70, the foam coating liquid flows out through the expansion tube 40 and extends. Bubbles are formed through (50), and bubbles come out through the foam coating adapter (60) formed as a double tube at the end of the extension pipe (50).

At this time, the foam evenly comes out through a plurality of holes 62 formed in the back of the inner tube 61 of the foam coating adapter 60, the open surface 64 formed at the front end of the outer tube 63 It is possible to easily and easily apply the foam 20 to the tube surface 70 by allowing the outside to leak through).

As described above, when the foam 20 paints the entire tube surface 70 uniformly, the foam 20 is in the same state as that of the cap surface on the tube surface 70.

If there are leaking tubes at this stage, they can be detected. Again, the bubble 20 is uniformly inspected for leaks on the tube surface 70. When there is a leaking part, if the apparatus is made negative pressure (vacuum), either of the bubbles 20 on one tube surface is to be recessed, so the tube surface 70 needs to be confirmed. If a part of the applied foam 20 is seen to sink, it can be easily determined by the leak pipe. The appearance of the foam 20 is required to be confirmed within 2 hours after application because the foam disappears or changes over time.

The foam 20 generated after use may be removed from the defoamer containing the antifoaming agent through a defoamer.

Such a foam can easily seal a vertical tube hole because of good adhesion to the tube and less cohesion by self weight such as liquid. In addition, since the specific gravity of the foam itself is small and the small pressure difference due to the pinhole makes it easy to move the foam through the tube, the vacuum applied to the condenser causes the foam applied to the leaking portion to sink, making it easier to leak the tube. Can be determined.

In the present invention as described above, the leak tube can be detected by the bubble indentation according to the degree of the suction of the bubble, the detection sensitivity and discrimination is superior to any conventional method, and when the small hole of 0.1mm occurs and the leakage amount is 0.1ml / min It is very sensitive to the following, and the surfactant, the main ingredient of foam medicine, is LAS (Linear Alkylbenzene Sulfonate) used in shampoo, and is made of linear alkylbenzene, so it is easy to be decomposed by microorganisms. Easy to clean and easy to clean, it is a chemical used in most synthetic detergents. It is environmentally friendly and harmless to humans, so it has good stability during operation, and harmful substances in foam drugs are below the detection limit, and for COD, The amount of residue is extremely small, so it is not a problem. Sir effects are rare.

In addition, the adhesion to the tube hole is good, the coagulation action is low, the vertical tube can be easily sealed, and the sealing of the conventional condenser tube by plugging is also easy to seal the leak can be easily distinguished.

The method of identifying a multi-sea water leak tube using foam enables detection of minute leaks and leaks at the tube end, which are superior in sensitivity to conventional thin film methods and are difficult to detect in the past. It has the advantage of not requiring a high level of skill. Due to the characteristics of the foam liquid, it has little influence on the environment and workers, and its stability is excellent, so it is widely used in the field, and the economic effect shows that it can save pure water and fuel cost by reducing the CBD emission caused by the leakage of thermal power and nuclear condenser. It contributes to stable operation and reduces the cost by reducing the number of ECT methods conventionally used, and can reduce operating costs by preventing uninterrupted power plant.

The intangible effect can quickly cope with the leakage of multiple engines, and can prevent corrosion of the boiler tube and erosion of the turbine blades, which can be caused by the leakage of the condenser, thereby contributing to the stable supply of power. Considering that the loss of power generation tube due to delay of checking time such as nuclear power plant leakage occurs, about 1 billion won is lost, the intangible effect of accurate and rapid inspection of the leakage of the power tube is expected to be quite large. It is devised.

Claims (2)

In the leak check method of the condenser tube using sea water as cooling water for the heat exchange of nuclear power plants or thermal power plants, Applying the foam (20) developed by using the foam coating device (10) on both sides of the tube sheet and the device menhole or gasket, such as the condenser and the heat exchanger, by applying a vacuum (negative pressure) to the interior of the condenser Method of confirming the tube leaking part of the condenser and heat exchanger, characterized in that configured to find the leaking part by visually checking the state of the bubble 20 is sinking. The method of claim 1, The foam coating device 10 forms a flexible tube 40 on one side of the bubble bomb 30, which is a pressure container containing the foam 20, and an extension tube 50 on the flexible tube 40. And, the foam coating adapter 60 is formed at the end of the extension pipe 50, the foam coating adapter 60 is formed of a double tube, the inner tube 61 is formed by forming a plurality of holes 62 on the back of the foam (20) to uniformly come out, the outer tube 63 is the front end portion is about 2cm open so that the bubble 20 is discharged through the open surface 64, characterized in that the condenser and heat exchanger To check the tube for leaks.