A tracer gas release device for leak detection of nuclear condenser heat transfer tubes

Abstract

The present invention discloses a tracer gas release device for leak detection of heat transfer tubes in a nuclear condenser, which is characterized in that it includes: a sealing cover, one end of which is in a wide-mouth shape, and this end is the first end; the other end is in a tubular shape, and this end is the second end; a connecting pipe, the air outlet of which is communicated with the second end of the sealing cover; a switch, which is arranged on the connecting pipe to control the on-off of the connecting pipe; a first connecting air pipe and a second connecting air pipe, which are respectively used to connect to a compressed air gas source and a tracer gas source; a first gas concentration meter and a second gas concentration meter, which are respectively connected to the first end of the sealing cover and are located on both sides of the axis of the second end. It can simultaneously inject tracer gas with a specified concentration and pressure into multiple heat transfer tubes of heat exchangers such as condensers, realizing simultaneous tracer gas leak detection for multiple heat transfer tubes and improving the leak detection efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of nuclear power detection equipment, and particularly relates to a tracer gas release device for leak detection of heat transfer tubes in a nuclear condenser. Background Art

[0002] A condenser is an important device that plays a cooling role in the thermal cycle of a nuclear power plant. The normal operation of the condenser, through heat exchange with cooling water, establishes and maintains a vacuum at the outlet of the steam turbine, and condenses the exhaust steam of the steam turbine into water as the feed water of the secondary circuit, forming a complete cycle. If the condenser has good sealing performance, it can reduce the exhaust temperature and exhaust pressure of the steam turbine and improve the thermal cycle efficiency. When the sealing performance of the condenser fails, it means that the condenser leaks. Among them, the more harmful one is the leakage of the heat transfer tubes in the condenser. The leakage of the heat transfer tubes will cause the ion concentration in the cooling water to rise. If the leaking heat transfer tubes cannot be quickly found, the unit will be forced to reduce power or even stop running according to the leakage situation of the heat transfer tubes.

[0003] Power plant operating units have developed a variety of leak detection methods for leak detection of condensers. Among them, the tracer gas leak detection method is a mature technology with high leak detection sensitivity and wide application. When using the tracer gas leak detection method to detect the heat transfer tubes in the condenser, a tracer gas with a specific concentration and pressure needs to be injected into the heat transfer tubes. If there is a leak in the heat transfer tubes in the detection area, the tracer gas will pass through the leak point of the heat transfer tube and enter the vacuum side of the condenser on the other side of the heat transfer tube. The detection personnel collect the tracer gas concentration signal at the outlet of the condenser vacuum system to judge the leakage situation of the heat transfer tubes in the area to be detected.

[0004] The number of heat transfer tubes in a nuclear power plant condenser is usually more than tens of thousands. Injecting tracer gas into each heat transfer tube will greatly extend the detection period and result in low detection efficiency. Summary of the Invention

[0005] The purpose of the present invention is to provide a tracer gas release device for leak detection of heat transfer tubes in a nuclear condenser, which can simultaneously inject a tracer gas with a specified concentration and pressure into multiple heat transfer tubes of heat exchangers such as condensers, so as to realize simultaneous tracer gas leak detection of multiple heat transfer tubes.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions: A tracer gas release device for leak detection of heat transfer tubes in a nuclear condenser, characterized in that it includes:

[0007] A sealing cover, one end of which is in a wide-mouth shape, and this end is the first end; the other end is in a tubular shape, and this end is the second end;

[0008] A connecting pipe, the gas outlet of which is connected to the second end of the sealing cover;

[0009] A switch, which is arranged on the connecting pipe to control the on-off of the connecting pipe;

[0010] The first connecting air pipe and the second connecting air pipe are respectively used to connect to a compressed air gas source and a tracer gas source;

[0011] The first gas concentration meter and the second gas concentration meter are respectively connected to the first end of the sealing cover and are located on both sides of the axis of the second end.

[0012] Preferably, a flow disturbing plate is arranged inside the first end, and flow disturbing holes communicating the first end and the second end are formed in the flow disturbing plate, and the flow disturbing holes are densely distributed on the flow disturbing plate.

[0013] Preferably, the releasing device includes an air pipe connected between the first connecting air pipe and the compressed air gas source and a first throttle valve installed on the air pipe.

[0014] Preferably, the releasing device includes a tracer gas pipe connected between the second connecting air pipe and the tracer gas source and a second throttle valve installed on the tracer gas pipe.

[0015] Preferably, the releasing device includes a gas distribution turbine rotatably installed inside the sealing cover and on one side of the air outlet of the connecting pipe.

[0016] Preferably, a sealing gasket is arranged on the end face of the first end of the sealing cover.

[0017] Preferably, a handle for easily holding and pressing the sealing cover is arranged on the outer side surface of the sealing cover.

[0018] Preferably, a transition section is arranged between the first end and the second end, and the transition section is in the shape of a quadrangular pyramid.

[0019] Preferably, the handle is symmetrically arranged on the outer side wall of the transition section.

[0020] The beneficial effect of the present invention is that tracer gas with a specified concentration and pressure can be simultaneously injected into multiple heat transfer tubes of heat exchangers such as condensers, realizing simultaneous tracer gas leak detection for multiple heat transfer tubes and improving the leak detection efficiency. Description of the Drawings

[0021] Figure 1 It is a schematic cross-sectional view of the tracer gas releasing device;

[0022] Figure 2 It is a schematic side view of the tracer gas releasing device;

[0023] Figure 3 It is a schematic diagram of the bottom situation of the tracer gas releasing device;

[0024] Figure 4 It is a schematic diagram of the tracer gas releasing device pressed on the tube sheet. Detailed implementation manners

[0025] The following provides a detailed description of the present invention in conjunction with the embodiments shown in the accompanying drawings:

[0026] See Figures 1 - 3 , the leak detection tracer gas release device for a nuclear condenser, comprising an air pipe 1, a first throttle valve 2, a first connecting pipe 3, a tracer gas pipe 4, a second throttle valve 5, a second connecting pipe 6, a connecting pipe 7, a switch 8, a sealing cover 9, a first handle 10, a second handle 11, a gas distribution turbine 12, a spoiler 13, a sealing gasket 14, a first gas concentration meter 15, a second gas concentration meter 16, and a heat transfer tube tube sheet 17.

[0027] Air pipe 1: Used to connect to a compressed air source to provide compressed air at a certain pressure, and its length can be adjusted according to actual needs to achieve the portability of the release device.

[0028] First throttle valve 2: Connected to the air pipe 1 and the first connecting pipe 3, and can adjust the gas flow rate of the compressed air through the self - contained knob.

[0029] First connecting pipe 3: Used to connect the first throttle valve 2 and the connecting pipe 7, and requires good airtightness.

[0030] Tracer gas pipe 4: Used to connect to a tracer gas source to provide tracer gas at a certain pressure, and its length can be adjusted according to actual needs to achieve the portability of the release device.

[0031] Second throttle valve 5: Connected to the tracer gas pipe 4 and the second connecting pipe 6, and can adjust the tracer gas flow rate through the self - contained knob.

[0032] Second connecting pipe 6: Used to connect the second throttle valve 5 and the connecting pipe 7, and requires good airtightness.

[0033] Connecting pipe 7: Used to adapt and connect the main body part of the release device, connected to the first connecting pipe 3 and the second connecting pipe 6, and a switch 8 is equipped on the connecting pipe 7.

[0034] Switch 8: Used for the inspection personnel to control the on - off of the connecting pipe 7 to achieve the release and stop actions of the tracer gas.

[0035] Sealing cover 9: One end of it is in a wide - mouth shape, which is the first end; the other end is in a tubular shape, which is the second end. There is a transition section between the first end and the second end, and the transition section is in a quadrangular pyramid shape. It constitutes the main body of the release device, used to accommodate components such as the gas distribution turbine 12 and the spoiler 13. The tracer gas and air are mainly mixed and proportioned inside the sealing cover 9. The sealing cover 9 is processed from engineering plastic material to reduce the overall weight of the release device.

[0036] The first handle 10: It is symmetrically distributed with the second handle 11 outside the sealing cover 9, which is convenient for the inspection personnel to hold the release device and operate it at the working position. The first handle 10 and the second handle 11 are designed with a structure that is convenient for clamping, which is convenient for the inspection personnel to clamp the release device with mechanical equipment and improve the detectability.

[0037] The second handle 11: Its function and structure are similar to those of the first handle 10.

[0038] The gas distribution turbine 12: It is installed inside the sealing cover 9 and can rotate driven by the air flow. The rotation speed is positively correlated with the gas flow rate, and it is used to preliminarily mix the tracer gas entering the sealing cover 9 with air. The gas distribution turbine 12 is processed by 3D printing technology and made of polymer materials to reduce the overall weight of the release device.

[0039] The spoiler 13: It is installed inside the sealing cover 9. Its structure is a flat plate full of through holes, and the periphery of the flat plate fits tightly with the inside of the sealing cover 9. The spoiler 13 divides the inside of the sealing cover 9 into two parts, one part is close to the gas distribution turbine 12, and the other part is close to the tube sheet 17 of the condenser heat transfer tube.

[0040] The sealing gasket 14: It is a polymer sealing material with a certain elasticity, which fits tightly on the bottom edge of the sealing cover 9. The width of its cross-section is slightly larger than the diameter of the heat transfer tube. The tracer gas release device is pressed on the area to be detected of the tube sheet 17 of the heat transfer tube. After being squeezed, the sealing gasket 14 fits tightly on the tube sheet 17 of the heat transfer tube, separating all the heat transfer tubes in the area to be detected from the other heat transfer tubes outside this area. See Figure 4 。

[0041] The first gas concentration meter 15: It is symmetrically distributed with the second gas concentration meter 16 on both sides of the sealing cover 9. The first gas concentration meter 15 is divided into two parts: a probe and a display dial. The probe part penetrates the outer wall of the sealing cover 9 and extends into the inside of the sealing cover 9, and is used to measure the concentration of the tracer gas inside the sealing cover 9 and display the concentration situation of the tracer gas in real time on the display dial outside.

[0042] The second gas concentration meter 16: Its function and structure are similar to those of the first gas concentration meter 15.

[0043] The tube sheet 17 of the heat transfer tube: The heat transfer tube bundle arranged according to a specific layout rule is sealed and welded on the tube sheet of the heat transfer tube, and it is also the position where the tracer gas is injected in the heat transfer tube leakage detection.

[0044] The method for releasing the tracer gas by using the above release device includes the following steps:

[0045] Step 1: Connect the air gas pipe 1 to the compressed air gas source, connect the tracer gas pipe 4 to the tracer gas gas source, and turn on the compressed air and tracer gas gas sources.

[0046] Step 2: According to the required tracer gas concentration, preliminarily calculate the ratio of tracer gas to air, and adjust the first throttle valve 2 and the second throttle valve 5 through the knob according to the ratio requirement.

[0047] Step 3: Turn on the switch 8 located on the connecting pipe 7. Compressed air flows through the air pipe 1, the first throttle valve 2, and the first connecting pipe 3 to the connecting pipe 7. The tracer gas flows through the tracer gas pipe 4, the second throttle valve 5, and the second connecting pipe 6 to the connecting pipe 7.

[0048] Step 4: The tracer gas and compressed air entering through the connecting pipe 7 enter the interior of the sealing cover 9. The airflow drives the gas distribution turbine 12 to rotate. The blades of the gas distribution turbine 12 cause the tracer gas and compressed air to be evenly mixed during the rotation process.

[0049] Step 5: Under the action of pressure, the preliminarily mixed tracer gas mixture enters the other side of the spoiler 13 through the densely distributed through holes on the spoiler 13. During this process, the tracer gas mixture will be further evenly mixed.

[0050] Step 6: The probes of the first gas concentration meter 15 and the second gas concentration meter 16 located inside the sealing cover 9 take samples of the mixed gas, and the tracer gas concentration is displayed in real time on the external dial.

[0051] Step 7: The detection personnel judge the mixing uniformity of the tracer gas and compressed air according to the display values of the two gas concentration meters, and at the same time judge the difference between the tracer gas concentration and the required concentration.

[0052] Step 8: According to the difference between the tracer gas concentration and the required concentration, adjust the airflow ratio of the two gases through the knob for the first throttle valve 2 and the second throttle valve 5 until the display value of the tracer gas concentration is consistent with the required concentration.

[0053] Step 9: The detection personnel press the tracer gas release device on the area to be detected of the heat transfer tube tube sheet 17 through the first handle 10 and the second handle 11. The width of the sealing gasket 14 is slightly larger than the diameter of the heat transfer tube. After being squeezed, it fits tightly on the heat transfer tube tube sheet 17, separating all the heat transfer tubes in the area to be detected from the other heat transfer tubes outside this area, ensuring that the tracer gas mixture does not enter the interior of the heat transfer tubes outside the area to be detected and generate leakage detection signal interference.

[0054] Step 10: Inject the tracer gas mixture with a specific concentration evenly into multiple heat transfer tubes in the area to be detected. The detection personnel judge the leakage situation of the heat transfer tubes in this area according to the change of the leakage detector signal.

[0055] Step 11: The inspector needs to prepare tracer gas release devices of multiple specifications. Tracer gas release devices of different specifications can cover the areas to be detected of the heat transfer tube tube sheets 17 with different areas, and tracer gas release devices of different specifications can be quickly replaced through the connecting pipes 7.

[0056] Step 12: If it is found that the signal of the leak detector increases, it indicates that there may be a leak in the heat transfer tubes in the area to be detected, and further detection needs to be carried out. The inspector replaces the tracer gas release device with a smaller specification and waits for the signal of the leak detector to drop to the initial level, and repeats Steps 9 to 10 for the above-mentioned area to be detected to judge the leak situation of the heat transfer tubes in this area.

[0057] Step 13: After multiple tests and continuously replacing the tracer gas release devices with smaller specifications, finally the inspector narrows down the suspicious range and locates and finds out the leaking heat transfer tubes.

[0058] Step 14: After temporarily plugging the leaking heat transfer tubes, the inspector repeats Steps 9 to 13 for other areas to be detected until the detection of all areas to be detected is completed.

[0059] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method of using a tracer gas release device for leak detection of heat transfer tubes in a nuclear condenser. The device includes: A sealing cover, one end of which is flared, and this end is the first end; The other end is tubular, and this end is the second end. A spoiler is provided inside the first end. The spoiler is provided with spoiler holes communicating the first end and the second end. The spoiler holes are densely distributed on the spoiler. A sealing gasket is provided on the end face of the first end of the sealing cover. A handle for easily gripping and pressing the sealing cover is provided on the outer side of the sealing cover. There is a transition section between the first end and the second end, and the transition section is in the shape of a quadrangular pyramid. The handles are symmetrically provided on the outer side wall of the transition section; A connecting pipe, the air outlet of which is communicated with the second end of the sealing cover; A switch, which is provided on the connecting pipe to control the on-off of the connecting pipe; A first connecting air pipe and a second connecting air pipe, which are respectively used to connect to a compressed air source and a tracer gas source; A first gas concentration meter and a second gas concentration meter, which are respectively connected to the first end of the sealing cover and are located on both sides of the axis of the second end; An air pipe connecting the first connecting air pipe and the compressed air source and a first throttle valve installed on the air pipe; A tracer gas pipe connecting the second connecting air pipe and the tracer gas source and a second throttle valve installed on the tracer gas pipe; A gas distribution turbine rotatably installed inside the sealing cover and on the side of the air outlet of the connecting pipe; It is characterized in that the method of using the above release device to release tracer gas includes the following steps: Step 1: Connect the air pipe to the compressed air source, connect the tracer gas pipe to the tracer gas source, and turn on the compressed air and tracer gas sources; Step 2: According to the required tracer gas concentration, preliminarily calculate the ratio of tracer gas to air, and adjust the first throttle valve and the second throttle valve through the knob according to the ratio requirement; Step 3: Turn on the switch on the connecting pipe. The compressed air flows through the air pipe, the first throttle valve, the first connecting air pipe to the connecting pipe, and the tracer gas flows through the tracer gas pipe, the second throttle valve, the second connecting air pipe to the connecting pipe; Step 4: The tracer gas and compressed air entering through the connecting pipe enter the inside of the sealing cover. The air flow drives the gas distribution turbine to rotate. The blades of the gas distribution turbine promote the uniform mixing of the tracer gas and the compressed air during the rotation process; Step 5: The preliminarily mixed tracer gas mixture, under the action of pressure, enters the other side of the spoiler through the through holes densely distributed on the spoiler. During this process, the tracer gas mixture will be further mixed evenly; Step 6: The probes of the first gas concentration meter and the second gas concentration meter located inside the sealing cover respectively sample the mixed gas, and the tracer gas concentration is displayed in real time on the external dial; Step 7: The detection personnel judge the degree of uniform mixing of the tracer gas and the compressed air according to the displayed values of the two gas concentration meters, and at the same time judge the difference between the tracer gas concentration and the required concentration; Step 8: According to the difference between the tracer gas concentration and the required concentration, adjust the gas flow ratio of the two gases by turning the knob on the first throttle valve and the second throttle valve until the displayed value of the tracer gas concentration is consistent with the required concentration; Step 9: The tester presses the tracer gas release device on the area to be tested on the tube sheet of the heat transfer tube through the first handle and the second handle. The width of the sealing gasket is slightly larger than the diameter of the heat transfer tube. After being squeezed, it fits tightly on the tube sheet of the heat transfer tube, separating all the heat transfer tubes in the area to be tested from the other heat transfer tubes outside this area, ensuring that the tracer mixed gas will not enter the interior of the heat transfer tubes outside the area to be tested and cause interference to the leak detection signal; Step 10: Inject the tracer mixed gas with a specific concentration evenly into multiple heat transfer tubes in the area to be tested. The tester judges the leakage situation of the heat transfer tubes in this area according to the change of the signal of the leak detector; Step 11: The tester needs to prepare tracer gas release devices of multiple specifications. The tracer gas release devices of different specifications can cover different areas of the tube sheet of the heat transfer tube to be tested, and the tracer gas release devices of different specifications can be quickly replaced through connecting pipes; Step 12: If it is found that the signal of the leak detector increases, it indicates that there may be a leakage of the heat transfer tube in the area to be tested, and further detection needs to be carried out; The tester replaces the tracer gas release device with a smaller specification and waits for the signal of the leak detector to drop to the initial level. Repeat steps 9 to 10 for the above-mentioned area to be tested to judge the leakage situation of the heat transfer tubes in this area; Step 13: After multiple tests and continuously replacing the tracer gas release device with a smaller specification, finally the tester narrows down the suspicious range and locates and finds out the heat transfer tube with leakage; Step 14: After temporarily plugging the leaking heat transfer tube, the tester repeats steps 9 to 13 for other areas to be tested until the detection of all areas to be tested is completed.

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