Recovery device for clear liquid at bottom of high-level storage tank

Abstract

The utility model discloses a high-level storage tank bottom clear liquid recovery device which comprises a tank entering device, a vacuum buffer tank, a first high-pressure gas buffer tank, a second high-pressure gas buffer tank and a head tank, a water inlet and outlet end is arranged at the lower end of the tank entering device, and the lower end of the tank entering device is arranged in a high-level storage tank. The vacuum buffer tank is connected with the exhaust end of the tank entering device, the first high-pressure gas buffer tank and the second high-pressure gas buffer tank are connected with the gas inlet end of the tank entering device, the drainage end of the tank entering device is connected with the head tank, and the position of the head tank is higher than that of the tank entering device. The tank entering device is free of mechanical and electronic elements, power is provided by gas in the clear liquid recovery process, and the tank entering device has good irradiation resistance and maintenance-free performance and high working efficiency. According to the utility model, trepanning on the storage tank can be avoided, and a miniaturized recovery device is installed by using the existing channel for entering and exiting the storage tank, namely the instrument sleeve, so that the radiation protection difficulty is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of nuclear facility decommissioning, in particular to a device for retrieving the clear liquid at the bottom of a high-level radioactive waste storage tank. Background Art

[0002] High-level radioactive waste storage tanks generally have the characteristics of high radiation dose levels, large size and scale, and complex internal conditions. Before decommissioning high-level radioactive waste storage tanks, it is necessary to pour out the waste liquid therein. Since the process systems of old nuclear facilities cannot be used during decommissioning, it is only possible to reinstall equipment to retrieve the waste liquid. Considering the dose rate of the storage tank and radiation protection issues, it is advisable to avoid opening holes in the storage tank as much as possible, but rather to preferentially retain the existing shielding layer of the storage tank and utilize the existing channels for entering and leaving the storage tank to retrieve the waste liquid. Summary of the Invention

[0003] The purpose of the utility model is to provide a device for retrieving the clear liquid at the bottom of a high-level radioactive waste storage tank.

[0004] To achieve the above purpose, the utility model is implemented according to the following technical solution:

[0005] The utility model includes an inlet device, a vacuum buffer tank, a first high-pressure gas buffer tank, a second high-pressure gas buffer tank, and a high-level tank. The lower end of the inlet device is provided with a water inlet and outlet end, and the lower end of the inlet device is placed inside the high-level radioactive waste storage tank. The vacuum buffer tank and the first high-pressure gas buffer tank are both connected to the exhaust end of the inlet device, the second high-pressure gas buffer tank is connected to the intake end of the inlet device, the drainage end of the inlet device is connected to the high-level tank, and the high-level tank is set at a position higher than that of the inlet device.

[0006] Furthermore, the inlet device is composed of an inlet pipe body, a vacuum suction pipe, a high liquid level detection pipe, a low liquid level detection pipe, a lifting pipe, an RFD module, an RFD module inlet hole, a passive one-way flow-limiting component, and a bottom foot support. A plurality of the bottom foot supports are fixedly arranged at the lower end of the passive one-way flow-limiting component. An inlet is arranged in the middle of the lower end of the passive one-way flow-limiting component. The upper edge of the lower end of the passive one-way flow-limiting component is connected to the lower end of the inlet pipe body. The upper end water outlet of the passive one-way flow-limiting component is connected to the RFD module. The RFD module is provided with an RFD module inlet hole. The outlet of the RFD module is connected to the lower end of the lifting pipe. The upper end of the lifting pipe is connected to the inlet of the high-level tank. The vacuum suction pipe is connected to the upper end of the inlet pipe body in communication. The high liquid level detection pipe is located in the upper section inside the inlet pipe body. The lower end of the low liquid level detection pipe is located in the lower section inside the inlet pipe body. The vacuum suction pipe is simultaneously connected to the first high-pressure gas buffer tank and the vacuum buffer tank. The low liquid level detection pipe is connected to the second high-pressure gas buffer tank.

[0007] Preferably, the RFD module is an RFD module integrated with an eddy current disk and a collision jet disk flow limiting element.

[0008] The beneficial effects of the present utility model are as follows:

[0009] The present utility model is a device for retrieving the clarified liquid at the bottom of a high-level radioactive waste storage tank. Compared with the prior art, the inlet device of the present utility model has no mechanical and electronic components, and the process of retrieving the clarified liquid relies on gas to provide power, having good radiation resistance and maintenance-free performance, as well as high working efficiency. The present utility model can avoid opening holes in the storage tank, and install a miniaturized retrieval device by using the existing channels for entering and leaving the storage tank, namely instrument sleeves, so as to reduce the difficulty of radiation protection. Description of the Drawings

[0010] Figure 1 is the system structure principle block diagram of the present utility model;

[0011] Figure 2 is the external structure schematic diagram of the inlet device of the present utility model;

[0012] Figure 3 is the internal structure schematic diagram of the inlet device of the present utility model.

[0013] In the figure: high-level radioactive waste storage tank 1, inlet device 2, vacuum buffer tank 3, first high-pressure gas buffer tank 4, second high-pressure gas buffer tank 5, elevated tank 6, inlet pipe body 21, vacuum suction pipe 22, high liquid level detection pipe 23, low liquid level detection pipe 24, lifting pipe 25, RFD module 26, RFD module inlet hole 27, passive one-way flow limiting component 28, bottom foot support 29. Detailed Embodiments

[0014] The following further describes the present utility model in conjunction with the drawings and specific embodiments. The illustrative embodiments and explanations of this utility model are used to explain the present utility model, but do not limit the present utility model.

[0015] As Figures 1-3 shown: The present utility model includes an inlet device 2, a vacuum buffer tank 3, a first high-pressure gas buffer tank 4, a second high-pressure gas buffer tank 5, and an elevated tank 6. The lower end of the inlet device 2 is provided with a water inlet and outlet end. The lower end of the inlet device 2 is placed inside the high-level radioactive waste storage tank 1. The vacuum buffer tank 3 is connected to the exhaust end of the inlet device 2. The first high-pressure gas buffer tank 4 and the second high-pressure gas buffer tank 5 are connected to the intake end of the inlet device 2. The drainage end of the inlet device 2 is connected to the elevated tank 6. The elevated tank 6 is arranged at a position higher than the inlet device 2.

[0016] Further, the tank inlet device 2 is composed of an inlet pipe body 21, a vacuum suction pipe 22, a high liquid level detection pipe 23, a low liquid level detection pipe 24, a lifting pipe 25, an RFD module 26, an RFD module inlet hole 27, a passive one-way flow limiting component 28, and a bottom foot support 29. A plurality of the bottom foot supports 29 are fixedly arranged at the lower end of the passive one-way flow limiting component 28. An inlet is arranged in the middle of the lower end of the passive one-way flow limiting component 28. The upper edge of the upper end of the passive one-way flow limiting component 28 is connected to the lower end of the inlet pipe body 21. The water outlet at the upper end of the passive one-way flow limiting component 28 is connected to the RFD module 26. The RFD module inlet hole 27 is arranged on the RFD module 26. The outlet of the RFD module 26 is connected to the lower end of the lifting pipe 25. The upper end of the lifting pipe 25 is connected to the inlet of the high-level tank 6. The vacuum suction pipe 22 is connected to the upper end of the inlet pipe body 21 in communication. The high liquid level detection pipe 23 is located in the upper section inside the inlet pipe body 21. The lower end of the low liquid level detection pipe 24 is located in the lower section inside the inlet pipe body 21. The vacuum suction pipe 22 is simultaneously connected to the first high-pressure gas buffer tank 4 and the vacuum buffer tank 3. The low liquid level detection pipe 24 is connected to the second high-pressure gas buffer tank 5.

[0017] Preferably, the RFD module 26 is an RFD module integrating an eddy current disk and a counter-jet disk flow limiting element.

[0018] The vacuum buffer tank 3 is connected to a vacuum pump. During the suction process, the vacuum pump is turned on to make the inside of the inlet pipe body 21 in a negative pressure state, so that the clear liquid in the high-level radioactive storage tank 1 to be retrieved is sucked into the inlet pipe body 21.

[0019] The second high-pressure gas buffer tank 5 is connected to the low liquid level detection pipe 24 through a pipeline. During the pressure impulse process, compressed air is turned on to press the liquid entering the low liquid level detection pipe 24 during the suction process into the inlet pipe body 21.

[0020] The first high-pressure gas buffer tank 4 is connected to the inlet pipe body 21 through the vacuum suction pipe 22. During the pressure impulse process, compressed air is turned on to press the liquid entering the inlet pipe body 21 during the suction process into the lifting pipe 25.

[0021] The high-level tank 6 is connected to the lifting pipe 25. The liquid during the pressure impulse enters the high-level tank 6 through the lifting pipe 25 and enters the subsequent pipeline. A passive flap valve relying on its own weight for sealing is arranged inside to inhibit the liquid backflow phenomenon during the suction stage.

[0022] Example:

[0023] The inlet pipe body 21 is a long straight stainless steel pipe with an outer diameter of 48 mm and an inner diameter of 45 mm. The lifting pipe 25 is a long straight stainless steel pipe with an outer diameter of 12 mm and an inner diameter of 10 mm. Its upper part is connected to the high-level tank 6 and is used for the transfer and transportation of subsequent residual liquid. The high-level detection pipe 23 is a long straight stainless steel round pipe with an open bottom, an outer diameter of 20 mm, an inner diameter of 18 mm, and a length of 3700 mm. The distance from the open bottom to the bottom of the piston cylinder is 4400 mm. The top of the high-level detection pipe 23 is connected to a stainless steel pipe with an outer diameter of 6 mm and an inner diameter of 4 mm. The high-level detection pipe 23 is connected to a differential pressure transmitter and is used to detect in real time whether the high level has been reached. The low-level detection pipe 24 is a thin straight stainless steel pipe with an outer diameter of 6 mm and an inner diameter of 4 mm. Its bottom is 450 mm away from the bottom of the inlet pipe body 21, and its top is connected to a differential pressure transmitter and is used to detect in real time whether the low level has been reached. The top of the inlet pipe body 21 is an upper cover, on which there is a high-pressure air / vacuum suction pipeline, which is the power source for the operation of the RFD module 26.

[0024] The function of the high-level detection pipe 23 is to monitor the liquid level in the piston cylinder during the suction process. When the liquid level exceeds a certain height of the high-level detection pipe 23, the suction process stops and switches to the pressure impulse process. The function of the low-level detection pipe 24 is to monitor the liquid level in the piston cylinder during the pressure impulse process. When the liquid level is lower than a certain height of the low-level detection pipe 24, the pressure impulse process stops and switches to the suction process.

[0025] Whether the suction process stops is judged by the pressure value of the differential pressure gauge connected to the high-level detection pipe 23, that is, the high-level differential pressure or the suction time. This differential pressure gauge is respectively connected to the high-level detection pipe 23 and the top cover of the inlet pipe body 21. When the liquid level in the inlet pipe body 21 reaches the opening of the high-level detection pipe 23, the value of the differential pressure gauge increases with the rise of the liquid level. When the value of the differential pressure gauge reaches the set high limit, the suction stops. In addition, in addition to the differential pressure gauge, the suction time can also be set before the retrieval. When the suction time reaches the set value, the suction can also stop.

[0026] The pressure impulse process is divided into high-pressure impulse and residual pressure impulse. Whether the pressure impulse process stops is judged by the pressure value of the differential pressure gauge connected to the low-level detection pipe 24, that is, the low-level differential pressure or the pressure impulse time. This differential pressure gauge is respectively connected to the low-level detection pipe 24 and the top cover of the inlet pipe body 21. During the pressure impulse process, two limit values need to be set, corresponding to the lower limit of the low level for the high-pressure impulse process and the lower lower limit of the low level for the residual pressure impulse process respectively. During the high-pressure impulse process, compressed gas acts on the liquid in the low-level detection pipe and the piston cylinder respectively. During the residual pressure impulse process, the compressed gas is closed, and the residual pressure in the inlet pipe body 21 is used to maintain the subsequent pressure impulse process. During the pressure impulse process, the value of the differential pressure gauge decreases with the decrease of the liquid level in the piston cylinder. When the value of the differential pressure gauge reaches the set limit value, the pressure impulse stops. In addition, in addition to the differential pressure gauge, the pressure impulse time can also be set before the retrieval. When the pressure impulse time reaches the set value, the pressure impulse can also stop.

[0027] The RFD module 26 integrates two layers of flow-limiting elements, namely, the eddy current disk and the impinging jet disk. The function of integrating the flow-limiting elements is as follows: when the retrieval tooling enters the pressure-impulse state, if a large amount of fluid enters the flow-limiting elements, a high-resistance eddy current will be formed in the eddy current disk, and at the same time, a high-flow-resistance area will be formed in the impinging jet disk due to jet impingement, so as to ensure that a large amount of fluid will not return to the high-level radioactive waste storage tank 1 through the integrated flow-limiting elements, but enter the riser 25 for retrieval and lifting.

[0028] The high-level tank 6 is connected to the riser 25. The liquid for pressure-impulse enters the high-level tank 6 through the riser 25 and then enters the subsequent pipeline. A passive flap valve that relies on its own weight for sealing is arranged inside to suppress the liquid backflow phenomenon during the suction stage.

[0029] The implementation method of the present utility model includes the following steps:

[0030] 1. Set the vacuum degree of the vacuum buffer tank 3, that is, the suction vacuum degree of the RFD module 26 during the suction stroke. The range of its vacuum degree is set between -75 kPa and -68 kPa. This vacuum degree can physically ensure that the rising height of the high-level radioactive waste liquid does not exceed the height of the inlet pipe body 21, so as to ensure that no large amount of high-level radioactive waste liquid enters the vacuum system.

[0031] 2. Set the pressure value of the second high-pressure gas buffer tank 5. The main purpose is to prevent high-level radioactive waste liquid from entering the low-level detection pipe 24 and further contaminating the corresponding pressure and differential pressure sensors during the pressure-impulse process of the RFD module 26. The pressure value is set between 400 kPa and 500 kPa.

[0032] 3. Set the pressure value of the first high-pressure gas buffer tank 4. The main purpose is to provide high-pressure air for the pressure-impulse conveying process of the RFD module 26, which is the power source for the lifting and conveying of the residual liquid. The pressure value is set to 260 kPa.

[0033] 4. Set the high-level limit. During the suction process, when the instantaneous value of the high-level liquid level differential pressure of the RFD module 26 is greater than the set value of the high-level limit, the suction stroke ends and the pressure-impulse process enters. This value is set to 5 kPa.

[0034] 5. Set the low-level lower limit

[0035] During the pressure-impulse stroke process, when the instantaneous value of the low-level liquid level differential pressure of the RFD module 26 is less than the set value of the low-level lower limit, the high-pressure pressure-impulse process ends, and at this time, the residual pressure impulse process enters. This value is set to 110 kPa.

[0036] 6. Set the low-level lower-lower limit

[0037] During the pressure-impulse stroke process, when the instantaneous value of the low-level liquid level differential pressure of the RFD module 26 is less than the set value of the low-level lower-lower limit, the residual pressure impulse process ends, and the RFD will transfer to the suction process. This value is set to 50 kPa.

[0038] 7. Set the suction and pressure impulse time

[0039] In addition to the high limit, low lower limit, and very low lower limit, the RFD module 26 can automatically cycle between the suction and pressure impulse processes by setting the suction time and pressure impulse time. During this process, when the actual operation time of the suction process is greater than the set value, a high-level alarm will occur; when the actual operation time of the pressure impulse process is greater than the set value, a low-level alarm will occur. The value is set as 10s < suction time < 40s, 5s < pressure impulse time < 18s.

[0040] After installing the inlet pipe body 21 through the instrument sleeve, start the control system, and set the vacuum degree of the vacuum buffer tank 3, the pressure value of the second high-pressure gas buffer tank 5, the pressure value of the first high-pressure gas buffer tank 4, the high limit, the low lower limit, the very low lower limit, and the suction and pressure impulse time in the industrial control computer. After the parameter setting is completed, start the retrieval tooling. First, start the suction process. As the suction process proceeds, the liquid level in the piston cylinder gradually rises. When the liquid level exceeds a certain height of the high liquid level detection pipe and the high liquid level pressure difference reaches the set high limit, the suction process stops and switches to the pressure impulse process. At the beginning of the pressure impulse process, the compressed gas directly acts on the liquid in the low liquid level detection pipe 24 and the inlet pipe body 21. After the low liquid level pressure difference reaches the set low lower limit, the compressed gas is closed, and the residual pressure impulse process is entered. After the low liquid level pressure difference reaches the set very low lower limit, the pressure impulse process ends and the suction process is entered.

[0041] Attention should be paid to the installation and use of the residual liquid retrieval process system of the RFD module 26:

[0042] 1. Inlet tank installation: The inlet tank device 2 should be in a vertical state and installed through the instrument pipe. After the bottom support 29 of the passive one-way flow-limiting component 28 touches the bottom, seal and fix between the inlet tank device 2 and the instrument pipe.

[0043] 2. Pipeline connection: There are a total of four protruding pipelines at the top cover of the inlet tank device 2. After branching, the vacuum suction pipe 22 is respectively connected to the vacuum buffer tank 3 and the first high-pressure gas buffer tank 4. Among them, the pipeline of the first high-pressure gas buffer tank 4 has a low radioactivity level because it is always in a state of air outflow and can be placed in the medium and low radioactive area. Due to the possible existence of radioactive aerosols, the pipeline of the vacuum buffer tank 3 has a relatively high radioactive level, and shielding measures should be considered during installation and piping. The suction gas discharged from the vacuum buffer tank 3 should also be connected to the tail gas treatment system to prevent the emission gas from exceeding the standard. The high liquid level detection pipe 23 and the low liquid level detection pipe 24 have a low radioactive level and can be arranged in the medium and low radioactive areas. The lifting pipe 25 is directly connected upward to the high-level tank 6, and there is residual liquid flowing inside. Therefore, shielding measures should be considered for both the lifting pipe 25 and the high-level tank 6.

[0044] 3. Buffer tank: The second high-pressure gas buffer tank 5 and the first high-pressure gas buffer tank 4 are non-radioactive and can be arranged in the low-radiation area. Due to the possible entry of radioactive aerosols, shielding measures should be considered for the vacuum buffer tank 3.

[0045] 4. Differential pressure / pressure sensor: Since it is remotely connected to the pressure source through a thin stainless steel pipe, it can be arranged in the medium and low-radiation area.

[0046] 5. Control cabinet and industrial control computer: The signal transmission of all sensors and actuators is through cables and is remotely connected to the control cabinet in the form of aviation plugs. Therefore, the control cabinet can be placed in the operation room. The control cabinet and the industrial control computer are connected through a standard network cable and can also be placed in the operation room.

[0047] The above shows and describes the basic principles, main features and advantages of the present utility model. Those skilled in the art should understand that the present utility model is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present utility model. Without departing from the spirit and scope of the present invention, the present utility model will have various changes and improvements, and these changes and improvements all fall within the scope of the present utility model claimed. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents.

Claims

1. A device for retrieving the clear liquid at the bottom of a high-level radioactive waste storage tank, characterized in that: It includes a tank inlet device (2), a vacuum buffer tank (3), a first high-pressure gas buffer tank (4), a second high-pressure gas buffer tank (5), and a high-level tank (6). The lower end of the tank inlet device (2) is provided with a water inlet and outlet end, and the lower end of the tank inlet device (2) is placed inside the high-level radioactive waste storage tank (1). The vacuum buffer tank (3) is connected to the exhaust end of the tank inlet device (2). The first high-pressure gas buffer tank (4) and the second high-pressure gas buffer tank (5) are connected to the intake end of the tank inlet device (2). The drain end of the tank inlet device (2) is connected to the high-level tank (6), and the high-level tank (6) is located at a position higher than that of the tank inlet device (2).

2. The device for retrieving the supernatant liquid at the bottom of the high-level radioactive waste storage tank according to claim 1, wherein: The tank inlet device (2) is composed of a tank inlet pipe body (21), a vacuum suction pipe (22), a high-level detection pipe (23), a low-level detection pipe (24), a lifting pipe (25), an RFD module (26), an RFD module inlet hole (27), a passive one-way flow-limiting component (28), and a foot support (29). A plurality of the foot supports (29) are fixedly arranged at the lower end of the passive one-way flow-limiting component (28). An inlet is arranged in the middle of the lower end of the passive one-way flow-limiting component (28). The upper edge of the upper end of the passive one-way flow-limiting component (28) is connected to the lower end of the tank inlet pipe body (21). The upper end water outlet of the passive one-way flow-limiting component (28) is connected to the RFD module (26). The RFD module (26) is provided with the RFD module inlet hole (27). The outlet of the RFD module (26) is connected to the lower end of the lifting pipe (25). The upper end of the lifting pipe (25) is connected to the inlet of the high-level tank (6). The vacuum suction pipe (22) is connected to communicate with the upper end of the tank inlet pipe body (21). The high-level detection pipe (23) is located in the upper section inside the tank inlet pipe body (21). The lower end of the low-level detection pipe (24) is located in the lower section inside the tank inlet pipe body (21). The vacuum suction pipe (22) is simultaneously connected to the first high-pressure gas buffer tank (4) and the vacuum buffer tank (3). The low-level detection pipe (24) is connected to the second high-pressure gas buffer tank (5).

3. The device for retrieving the supernatant liquid at the bottom of the high-level radioactive waste storage tank according to claim 2, characterized in that: The RFD module (26) is an RFD module integrated with a vortex disk and a counter-jet disk flow-limiting element.

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