Helium Leak Detection and Helium Charging Device for Single Tube of Heat Exchanger and Detection Method

Abstract

The present invention belongs to the technical field of helium leak detection, and particularly relates to a helium charging device and a detection method for single-tube helium leak detection of a heat exchanger. It includes a helium gas source, a charging control device, a sealing plug, an intake pipeline, an exhaust pipeline, and a metal sealing fixture; there is a weld on the primary side of the tube sheet between the heat exchange tube and the primary side of the tube sheet, and a metal sealing fixture is provided between the primary side of the tube sheet and the protruding part of the heat exchange tube. When using this method for helium leak detection of the heat exchange tube weld, due to the high helium concentration, good sealing, and small space evacuated by the leak detector, using this method for helium leak detection has a high detection sensitivity, ensuring the reliability of the detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of helium leak detection, and particularly relates to a helium charging device and a detection method for single-tube helium leak detection of a heat exchanger. Background Art

[0002] The structure of the passive residual heat removal cooler (hereinafter referred to as the emergency residual heat removal) is a C-type heat exchanger without a sealed shell side, with a length, width and height of 4760×2380×6460, a dry weight of the equipment of 28 tons, and a heat transfer area of 249 m2.

[0003] According to the requirements, helium leak detection is carried out on the welds between the primary side heat exchange tubes and the tube sheets:

[0004] 1. A rectangular container needs to be made on the secondary side of the tube sheet. After the requirements for sealing the entire heat exchange tube, frame and tube sheet parts are met, a tracer gas (helium) is filled.

[0005] 2. After the welds of the primary side heat exchange tubes on the tube sheet are sealed, a helium mass spectrometer leak detector is connected for vacuum helium leak detection.

[0006] 3. Since the overall helium charging container is large in size and weighs more than 20 tons, the large-size rectangular structure container is extremely prone to deformation when vacuumizing and pressurizing, which limits the concentration of the tracer gas to not meet the requirements of helium leak detection.

[0007] The traditional helium leak detection container has a high cost, and the concentration of the tracer gas helium is 20% and cannot meet the technical requirements. Summary of the Invention

[0008] Aiming at the above deficiencies, the main purpose of the present invention is to overcome the disadvantages that the existing helium leak detection container has a high cost and the concentration of the tracer gas helium is 20% and cannot meet the technical requirements, and to provide a helium charging device and a detection method for single-tube helium leak detection of a heat exchanger.

[0009] The technical solution of the present invention is as follows:

[0010] A helium charging device for single-tube helium leak detection of a heat exchanger includes a helium gas source, an inflation control device, a sealing plug, an intake pipeline, an exhaust pipeline and a metal sealing fixture; there is a weld on the primary side of the tube sheet between the heat exchange tube and the primary side of the tube sheet, and a metal sealing fixture is provided between the primary side of the tube sheet and the protruding part of the heat exchange tube;

[0011] The helium gas provided by the helium gas source is connected to the lower part of the inflation control device through a pipeline and a control valve, and a helium gas concentration meter is connected to the inflation control device through a pipeline and a control valve;

[0012] Two air holes are provided on the inflation control valve, one is connected to the intake pipeline through a pipeline, and the other is connected to the exhaust pipeline through a pipeline to form a closed loop;

[0013] The inflation control device is provided with a hollow structure whose upper and lower ends are not connected to each other. The lower hollow structure is used to connect the helium gas source and the intake pipeline, and the upper hollow structure is used to connect the pressure gauge, the helium gas concentration meter, and the outlet pipeline.

[0014] A helium leak detection and helium filling device for a single tube of a heat exchanger. A pressure gauge is provided at the top of the inflation control device.

[0015] A helium leak detection and helium filling device for a single tube of a heat exchanger. A sealing plug is provided in the metal sealing fixture. The sealing plug wraps around and seals the heat exchange tube, and at the same time seals between the metal sealing fixture and the primary side of the tube sheet.

[0016] A helium leak detection and helium filling device for a single tube of a heat exchanger. The sealing plug is a conical boss hollow structure. The hollow part is the insertion space for the heat exchange tube, and it is divided into two concentric upper and lower hollow spaces. The diameter of the lower hollow cylinder is larger than that of the upper hollow cylinder. There is a shoulder transition at the connection of the two hollow spaces, and hollow structures for the intake pipeline and the outlet pipeline are provided on the shoulders on the left and right sides.

[0017] A helium leak detection and helium filling device for a single tube of a heat exchanger. In the sealing plug, an included angle is provided between the hollow structures of the intake pipeline and the outlet pipeline and the insertion space of the heat exchange tube.

[0018] A helium leak detection and helium filling device for a single tube of a heat exchanger. The cross-section of the sealing plug is cut axially through at the middle position between the intake pipeline and the outlet pipeline.

[0019] A helium leak detection and helium filling device for a single tube of a heat exchanger. The metal sealing fixture is a cube-shaped hollow structure. The hollow part matches the structure of the sealing plug. The metal sealing fixture includes metal clamp set A and metal clamp set B. Threads are provided at both ends of metal clamp set A, and through screw holes are provided at the positions corresponding to the threads on metal clamp set B. The clamping and sealing of the metal sealing fixture are achieved by their cooperation relationship.

[0020] A helium leak detection method for a single tube of a heat exchanger, including Step 1: Install a rubber plug on the outer wall of the heat exchange tube, and install a metal jacket and fastening bolts;

[0021] Step 2: Connect the tube sheet, the weld sealing device of the heat exchange tube, and the helium leak detection together;

[0022] Step 3: Turn on the leak detector to make the instrument enter the vacuum helium leak detection state;

[0023] Step 4: Operate using the helium leak detection and helium filling detection device for a single tube of a heat exchanger;

[0024] Step 5: Perform helium leak detection on a simulated part equipped with a standard leak hole and record the leak rate value;

[0025] Step 6: Detect and record the leak rate value of the leak detector. If the leak rate value is much smaller than the leak rate value measured for the simulation part, it is considered qualified.

[0026] A helium leak detection method for a single tube of a heat exchanger. The said Step 4 includes: Step 1, connect the equipment according to the single tube helium leak detection helium charging device diagram;

[0027] Step 2: Connect the equipment according to the single tube helium leak detection helium charging device diagram;

[0028] Step 3: Turn on the gas source and the valve to allow helium to flow through the intake pipeline, the exhaust pipeline and the inflation control device;

[0029] Step 4: Connect the equipment according to the single tube helium leak detection helium charging device diagram;

[0030] Step 5: Adjust the control valve connected to the helium gas source to regulate the intake air so that the pressure gauge reaches the specified pressure; up to 35 KPa of gauge pressure;

[0031] Step 6: Open the control valve connected to the helium gas concentration meter for helium replacement;

[0032] Step 7: Measure the helium gas concentration in the exhaust pipeline with a helium gas concentration meter to make it reach 100% vol;

[0033] Step 8: Close the control valve connected to the helium gas concentration meter and maintain the pressure of the pressure gauge to conduct helium leak detection on the welds of the tube sheet heat exchange tubes.

[0034] The beneficial effects of the present invention are as follows:

[0035] It only takes 1 - 2 minutes to complete the installation of the helium charging device once.

[0036] The single tube helium charging device has good sealing performance. By using the replacement method, a helium gas concentration of 100% vol can be achieved in about 10 seconds.

[0037] Through the simulation test with the standard leak hole of the simulation part, the requirements for detecting the acceptance leak rate of the emergency exhaust heat exchanger can be met.

[0038] When using this method for helium leak detection of the heat exchange tube welds, due to the high helium gas concentration, good sealing and small evacuated space of the leak detector, this method of helium leak detection has high detection sensitivity and ensures the reliability of the detection. Description of the Drawings

[0039] Figure 1 is a schematic diagram of the single tube helium leak detection helium charging device of the present invention;

[0040] Figure 2 is a schematic diagram of the structure of the sealing plug;

[0041] Figure 3 is a schematic diagram of the cutting position of the sealing plug;

[0042] Figure 4 is a schematic structural diagram of a metal sealing fixture;

[0043] Figure 5 is the A-A interface diagram of the metal sealing fixture;

[0044] Figure 6 is the flow chart of the single-tube helium leak detection method for the heat exchanger.

[0045] In the figure: 1. Helium gas source; 2. Helium gas concentration meter; 4. Pressure gauge; 5. Inflation control device; 6. Heat exchange tube; 7. Sealing plug; 8. Inlet gas pipeline; 9. Outlet gas pipeline; 10. Metal sealing fixture; 11. Weld seam on the primary side of the tube sheet. Specific implementation manners

[0046] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] A single-tube helium leak detection helium charging device for a heat exchanger includes a helium gas source 1, an inflation control device 5, a sealing plug 7, an inlet gas pipeline 8, an outlet gas pipeline 9 and a metal sealing fixture 10.

[0048] The helium gas provided by the helium gas source 1 is connected to the lower part of the inflation control device 5 through a pipeline and a control valve, and the helium gas concentration meter 2 is connected to the inflation control device 5 through a pipeline and a control valve.

[0049] There are two air holes provided on the inflation control valve 5. One is connected to the inlet gas pipeline 8 through a pipeline, and the other is connected to the outlet gas pipeline 9 through a pipeline to form a closed loop.

[0050] A pressure gauge 4 is provided at the top of the inflation control device 5.

[0051] The inflation control device 5 is provided with a hollow structure whose upper and lower ends are not connected to each other. The lower hollow structure is used to connect the helium gas source 1 and the inlet gas pipeline 8, and the upper hollow structure is used to connect the pressure gauge 4, the helium gas concentration meter 2 and the outlet gas pipeline 9.

[0052] There is a weld seam 11 on the primary side of the tube sheet between the heat exchange tube 6 and the primary side of the tube sheet, and a metal sealing fixture 10 is provided between the primary side of the tube sheet and the protruding part of the heat exchange tube.

[0053] A sealing plug 7 is provided in the metal sealing fixture 10. The sealing plug 7 wraps and seals the heat exchange tube 6, and at the same time seals between the metal sealing fixture 10 and the primary side of the tube sheet.

[0054] The sealing plug 7 has a conical boss hollow structure. The hollow part is the insertion space for the heat exchange tube 6 and is divided into two concentric upper and lower hollow spaces. The diameter of the lower hollow cylinder is larger than that of the upper hollow cylinder. There is a shoulder transition at the connection of the two hollow spaces, and hollow structures for the intake pipe 8 and the exhaust pipe 9 are provided on the left and right shoulders.

[0055] An angle is provided between the hollow structures of the intake pipe 8 and the exhaust pipe 9 and the insertion space of the heat exchange tube 6.

[0056] The cross-section of the sealing plug 7 is cut axially through at the middle position between the intake pipe 8 and the exhaust pipe 9.

[0057] The metal sealing fixture 10 has a cube hollow structure. The hollow part matches the structure of the sealing plug 7. The metal sealing fixture 10 includes a metal clip set A and a metal clip set B. Threads are provided at both ends of the metal clip set A, and through screw holes are provided at the positions corresponding to the threads on the metal clip set B. The clamping and sealing of the metal sealing fixture 10 are achieved by their cooperation relationship.

[0058] A single-tube helium leak detection method for heat exchangers;

[0059] Step 1: Install the rubber plug on the outer wall of the heat exchange tube, and install the metal jacket and fastening bolts.

[0060] Step 2: Connect the tube sheet, the weld sealing device of the heat exchange tube and the helium leak detection together.

[0061] Step 3: Turn on the leak detector to make the instrument enter the vacuum helium leak detection state.

[0062] Step 4: Operate using the single-tube helium leak detection helium charging detection device for the heat exchanger.

[0063] Step 5: Conduct helium leak detection on the simulation part equipped with a standard leak hole and record the leak rate value.

[0064] Step 6: Record the leak rate value of the leak detector during product detection. If this leak rate value is much smaller than the leak rate value measured by the simulation part, it is qualified.

[0065] The said Step 4 includes, Step 1, connect the equipment according to the single-tube helium leak detection helium charging device diagram;

[0066] Step 2: Connect the equipment according to the single-tube helium leak detection helium charging device diagram;

[0067] Step 3: Turn on the gas source and valve to make the helium gas flow through the intake pipe, the exhaust pipe and the inflation control device;

[0068] Step 4: Connect the equipment according to the single-tube helium leak detection helium charging device diagram;

[0069] Step 5: Adjust the control valve connected to the helium gas source, regulate the intake air to make the pressure gauge reach the specified pressure, up to 35 KPa of gauge pressure;

[0070] Step 6: Open the control valve connected to the helium gas concentration meter to conduct helium replacement;

[0071] Step 7: Use the helium gas concentration meter to measure the helium gas concentration in the outlet pipeline to make it reach 100% vol;

[0072] Step 8: Close the control valve connected to the helium gas concentration meter, maintain the pressure of the pressure gauge and conduct helium leak detection on the welds of the tube sheet heat exchange tubes.

[0073] Install a single-tube sealing device on the heat transfer tubes on the secondary side of the tube sheet. This device forms a sealed space together with the outer surface of the heat transfer tubes and the surface of the tube sheet.

[0074] Replace the air in this sealed space by means of helium replacement, and finally make the helium gas concentration in this sealed space reach 99.99% (detected by a helium gas concentration measuring instrument) and maintain a relative positive pressure. At the same time, install a vacuum pumping device on the side of the tube-tube sheet weld to pump vacuum, so that a pressure difference of not less than 0.1 MPa is formed on both sides of the weld. When using this method to conduct helium leak detection on the welds of the heat exchange tubes, due to the high helium gas concentration, good sealing, and small space evacuated by the leak detector, using this method for helium leak detection has a high detection sensitivity and ensures the reliability of the detection.

Claims

1. A helium leak detection and helium filling device for a single tube of a heat exchanger, comprising a helium gas source, an inflation control device, a sealing plug, an inlet pipeline, an outlet pipeline and a metal sealing fixture; there is a weld on the primary side of the tube sheet between the heat exchange tube and the primary side of the tube sheet, and a metal sealing fixture is arranged between the primary side of the tube sheet and the protruding part of the heat exchange tube; It is characterized in that: The helium gas provided by the helium gas source is connected to the lower part of the inflation control device through a pipeline and a control valve, and a helium gas concentration meter is connected to the inflation control device through a pipeline and a control valve; Two air holes are arranged on the inflation control device, one is connected to the inlet pipeline through a pipeline, and the other is connected to the outlet pipeline through a pipeline to form a closed loop; A hollow structure with non - communicating upper and lower ends is arranged in the inflation control device. The lower hollow structure is used to connect the helium gas source with the inlet pipeline, and the upper hollow structure is used to connect the pressure gauge, the helium gas concentration meter and the outlet pipeline; A pressure gauge is arranged on the top of the inflation control device; A sealing plug is arranged in the metal sealing fixture. The sealing plug wraps and seals the heat exchange tube, and at the same time seals between the metal sealing fixture and the primary side of the tube sheet; The sealing plug is a conical boss hollow structure. The hollow part is the insertion space for the heat exchange tube, and it is divided into two concentric - axis upper and lower hollow spaces. The diameter of the lower hollow cylinder is larger than that of the upper hollow cylinder; there is a shoulder - type transition at the connection of the two hollow spaces, and hollow structures for the inlet pipeline and the outlet pipeline are arranged on the shoulders on the left and right sides.

2. A helium leak detection and helium filling device for a single tube of a heat exchanger according to claim 1, It is characterized in that: In the sealing plug, an included angle is arranged between the hollow structures for the inlet pipeline and the outlet pipeline and the insertion space of the heat exchange tube.

3. A helium leak detection and helium filling device for a single tube of a heat exchanger according to claim 1, It is characterized in that: The cross - section of the sealing plug is cut axially through at the middle position between the inlet pipeline and the outlet pipeline.

4. A helium leak detection and helium filling device for a single tube of a heat exchanger according to claim 1, It is characterized in that: The metal sealing fixture is a cube - shaped hollow structure. The hollow part matches the structure of the sealing plug. The metal sealing fixture includes metal clip set A and metal clip set B. Threads are arranged at both ends of metal clip set A, and through - hole screw holes are arranged at the positions corresponding to the threads of metal clip set B. The clamping and sealing of the metal sealing fixture are realized by their cooperation relationship.

5. A method for helium leak detection of a single tube of a heat exchanger using the device according to claim 4; including Step 1, installing the sealing plug and the outer wall of the heat exchange tube, and installing metal clip sets A, B and fastening bolts; Step 2, connecting the tube sheet, the heat exchange tube weld sealing device with the helium leak detection instrument; Step 3, turning on the helium leak detection instrument to make the instrument enter the vacuum helium leak detection state; It is characterized in that: Step 4, operating using the helium leak detection and helium filling device for a single tube of a heat exchanger; Step 5, performing helium leak detection on a simulation part equipped with a standard leak hole and recording the leak rate value; Step 6, product detection, recording the leak rate value of the helium leak detection instrument. If this leak rate value is much smaller than the leak rate value measured by the simulation part, it is qualified.

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