Vacuum drying and dehumidifying device suitable for spent fuel dry storage

Abstract

The utility model relates to the field of electrical technology, in particular to a vacuum drying and dehumidifying device suitable for spent fuel dry storage, which comprises a VDS system and a vacuum pump, the VDS system and the vacuum pump are both arranged on a fixing frame, and a VDS hose on the VDS system is provided with a heating vacuum drying and dehumidifying device used for heating the VDS hose; the heating vacuum drying and dehumidifying device comprises a stainless steel straight barrel composed of two semi-cylindrical barrels, the two semi-cylindrical barrels are connected through a hinge, and the two semi-cylindrical barrels are fixed through a rotating shaft buckle. A controller is installed on the top of the heating vacuum drying and dehumidifying device, an electric wire is connected to the controller, and a displayer is installed on the top of the controller. Heat preservation cotton is arranged on the inner side of the stainless steel straight cylinder. After the vacuum drying and dehumidifying device is adopted, the working time of workers near a hot spot is shortened, the working condition that the workers make contact with contaminated objects is eliminated, and the exposure dose of the workers is reduced through a time protection method and a shielding protection method.

Description

Technical Field

[0001] The utility model relates to the field of electrical technology, in particular to a vacuum drying and dehumidifying device suitable for spent fuel dry storage. Background Art

[0002] In the early stage of construction, nuclear power plants have built storage pools for spent fuel. Due to the limited storage capacity of spent fuel pools, as the operating years of the units increase, the amount of spent fuel components generated increases year by year, and conventional storage can no longer meet the rapid development of China's nuclear power industry. With the development and utilization of China's nuclear power technology, the domestic nuclear power industry has gradually introduced, digested, absorbed and promoted the spent fuel dry storage process.

[0003] During the dry storage process, the sealed storage container containing the spent fuel assembly needs to be evacuated so that the water molecules inside the container are completely discharged. After the pressure in the container drops to below 2.0 torr and stabilizes for half an hour, it can be determined that the pressure in the container meets the requirements of the spent fuel dry storage process. At this time, 99.999% helium needs to be injected into the sealed storage container to between 12.4 and 22 kPa so that the spent fuel assembly is immersed in an inert gas environment. The spent fuel dry storage process vacuum system (hereinafter referred to as VDS) is composed of thirteen high-precision vacuum ball valves, a six-way vacuum metal pipe, a four-way vacuum metal pipe, two three-way vacuum metal pipes, three absolute pressure transmitters, two positive pressure transmitters and several vacuum metal pipes. It connects the vacuum pump, Roots blower and sealed storage container together through hoses of different lengths. When the VDS system is used to evacuate the sealed storage container, sometimes the boric acid solution will be deposited due to the presence of depressions in the pipeline. At this time, the vacuum drying efficiency will be greatly reduced. Sometimes, the temperature in the pipe will drop below 0 degrees Celsius due to the rapid drop in the vacuum degree in the system, resulting in boric acid ice crystals. The temperature in the reactor hall is as high as 40 to 45 degrees Celsius, and the metal pipe will quickly conduct heat, causing the internal boric acid ice crystals to melt quickly. However, the transparent hose has poor thermal conductivity, and there is a low-lying area at the connection between the VDS metal pipe and the hose, which causes the boric acid water to accumulate and freeze. At this time, the rate of vacuum drop will slow down drastically. The occurrence of ice will have a huge impact on the vacuum pumping efficiency of VDS, greatly affect the dry storage period, increase the working time of the spent fuel dry project staff in the radiation control area, and increase the exposure measurement of personnel. The spent fuel dry project used metal bellows instead of transparent hoses for vacuum pumping. However, since it is impossible to see the situation inside the metal bellows, it is impossible to grasp the water flow situation in the pipe in real time, which has caused great interference to the early helium purge, initial vacuum pumping and other working conditions.

[0004] In summary, when ice forms in the pipeline under the vacuum condition of the spent fuel dry storage process, the staff needs to disconnect the hose from the VDS, break the vacuum environment inside the container, and remove the ice cubes. Then, reconnect the hose to the VDS and restart the vacuum drying. This operation may delay the construction period by 10 to 20 hours, greatly increasing the working hours near the hot spot. Moreover, the removed ice crystals are contaminated boric acid ice crystals, posing a significant contamination risk to the staff.

[0005] At this time, a vacuum drying and dehumidification device suitable for spent fuel dry storage is needed to achieve the purpose of de-icing and dehumidifying the hose without breaking the vacuum condition inside the container. Utility Model Content

[0006] The purpose of the present utility model is to address the deficiencies of the prior art and provide a vacuum drying and dehumidification device suitable for spent fuel dry storage to solve the problems raised in the above background technology.

[0007] To achieve the above purpose, the present utility model provides the following technical solution: A vacuum drying and dehumidification device suitable for spent fuel dry storage, including a VDS system and a vacuum pump. Both the VDS system and the vacuum pump are installed on a fixed frame. A heating vacuum drying and dehumidification device is installed on the VDS hose of the VDS system for heating the VDS hose.

[0008] The heating vacuum drying and dehumidification device includes a stainless steel straight cylinder composed of two semi-cylindrical barrels. The two semi-cylindrical barrels are connected by hinges and fixed by a shaft buckle.

[0009] A controller is installed on the top of the heating vacuum drying and dehumidification device. The controller is connected with an electric wire, and a display is installed on the top of the controller.

[0010] Heat-insulating cotton is provided inside the stainless steel straight cylinder. Heating wires are provided inside the heat-insulating cotton, and a patch type temperature sensor is also installed inside the heat-insulating cotton.

[0011] As a preferred technical solution of the present utility model, the controller is installed on the heating vacuum drying and dehumidification device by screws, and the display is installed on the controller by screws.

[0012] As a preferred technical solution of the present utility model, the display consists of a switch button, a temperature adjustment button, a display screen, a buzzer, and an LED indicator light.

[0013] As a preferred technical solution of the present utility model, the controller is connected to an external power supply through an electric wire.

[0014] As a preferred technical solution of the present utility model, the heating wire is electrically connected to the controller, and the controller is electrically connected to the display.

[0015] As a preferred technical solution of the present utility model, the display is electrically connected to the patch type temperature sensor through the controller.

[0016] As a preferred technical solution of the present utility model, the heating wire is wrapped with nickel-chromium wire by high-strength polyester paint, and is evenly wound on the asbestos wire core by a spiral winding process, and is distributed in an S shape on both sides inside the stainless steel straight cylinder.

[0017] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0018] 1. Compared with the method of breaking the vacuum environment in the container to open the pipeline for deicing, the method of heating and melting ice to eliminate the boric acid ice crystals in the pipeline greatly reduces the construction period required for the process flow;

[0019] 2. By heating the pipeline, the evaporation amount of the boric acid solution in the pipeline is increased, and the vacuum drying rate is increased;

[0020] 3. The vacuum drying and dehumidification device is fixed by using hinges and rotating shaft buckles, which ensures the stability of the device fixation while facilitating the disassembly and assembly of the device;

[0021] 4. A double screen is set to react the temperature in the pipeline and the system setting temperature in real time, which is convenient for the operator to identify;

[0022] 5. The heating wire is wrapped with nickel-chromium wire by high-strength polyester paint, and is evenly wound on the asbestos wire core by a spiral winding process, and is distributed in an S shape on both sides of the straight cylinder, which ensures the safety of the heating wire while taking into account the stable rise of the heating temperature.

[0023] 6. The controller is used to control the system power, and the power of the heating wire is adjusted by self-sensing the temperature in the straight cylinder, so as to achieve precise control of the system temperature. Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the VDS pipeline installation structure of the present utility model;

[0025] Figure 2 It is a schematic diagram of the closed structure of the heating vacuum drying and dehumidification device of the present utility model;

[0026] Figure 3 It is a schematic diagram of the open structure of the heating vacuum drying and dehumidification device of the present utility model.

[0027] In the figure: 1. Heating vacuum drying and dehumidifying device; 2. VDS system; 3. Vacuum pump; 101. Hinge; 102. Stainless steel straight cylinder; 103. Display; 104. Controller; 105. Rotating shaft buckle; 106. Thermal insulation cotton; 107. Electric wire; 108. Heating wire. Detailed implementation mode

[0028] The following elaborates on the preferred embodiments of the present utility model in conjunction with the accompanying drawings, so that the advantages and features of the present utility model can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present utility model.

[0029] Embodiment: Please refer to Figures 1-3 , the present utility model provides a technical solution: A vacuum drying and dehumidifying device suitable for dry storage of spent fuel includes a VDS system 2 and a vacuum pump 3. Both the VDS system 2 and the vacuum pump 3 are arranged on a fixed frame. A heating vacuum drying and dehumidifying device 1 is installed on the VDS hose of the VDS system 2 for heating the VDS hose;

[0030] The heating vacuum drying and dehumidifying device 1 includes a stainless steel straight cylinder 102 composed of two semi-cylindrical barrels. The two semi-cylindrical barrels are connected by a hinge 101 and fixed by a rotating shaft buckle 105;

[0031] A controller 104 is installed on the top of the heating vacuum drying and dehumidifying device 1. An electric wire 107 is connected to the controller 104, and a display 103 is installed on the top of the controller 104;

[0032] Thermal insulation cotton 106 is provided inside the stainless steel straight cylinder 102. A heating wire 108 is provided inside the thermal insulation cotton 106, and a patch type temperature sensor is also installed inside the thermal insulation cotton 106.

[0033] The controller 104 is installed on the heating vacuum drying and dehumidifying device 1 by screws, and the display 103 is installed on the controller 104 by screws.

[0034] The display 103 is composed of a switch button, a temperature adjustment button, a display screen, a buzzer and an LED indicator light.

[0035] The controller 104 is connected to an external power supply through the electric wire 107.

[0036] The heating wire 108 is electrically connected to the controller 104, and the controller 104 is electrically connected to the display 103.

[0037] The display 103 is electrically connected to the patch type temperature sensor through the controller 104.

[0038] The heating wire 108 is made of nickel-chromium wire wrapped by high-strength polyester paint, and is evenly wound around the asbestos core by a spiral winding process, and is distributed in an S shape on both sides inside the stainless steel straight cylinder 102.

[0039] Working principle: A vacuum drying and dehumidification device applicable to dry storage of spent fuel. The heating wire 108 is made of nickel-chromium wire wrapped by high-strength polyester paint, and is evenly wound around the asbestos core by a spiral winding process, and is distributed in an S shape on both sides of the stainless steel straight cylinder 102. When an electric current passes through the heating wire 108 to generate heat, the temperature inside the stainless steel straight cylinder 102 rises. When the temperature rises to 60 degrees Celsius, the thermistor senses the temperature inside the stainless steel straight cylinder 102 and transmits a signal to the controller. The controller controls the transformer inside the controller to step up or step down the voltage according to the received signal, so as to adjust the heating power of the heating wire 108 and keep it near the set value of "60 degrees Celsius". If the temperature exceeds the set value, the controller reduces the current passing through the heating wire to reduce the heating power; if the temperature does not reach the set value, the controller increases the current passing through the heating wire 108 to increase the heating power. The controller controls the temperature of the heating wire 108 to be stable near the set value during the heating process, realizing precise control of the temperature of the heating wire by the temperature controller.

[0040] A patch type temperature sensor is arranged inside the straight cylinder, which can detect the temperature of the pipeline inside the straight cylinder in real time and display it on the display 103 on the cylinder wall. The display 103 is composed of a switch button, a temperature adjustment button, a display screen, a buzzer, and an LED indicator light. When the display 103 is normally displaying, the left half of the screen displays the real-time temperature inside the straight cylinder, and the right half of the screen displays the set temperature of the vacuum drying and dehumidification device. Connect the device to the 220V power supply and press the power-on key. The dehumidification device starts to work. The current passes through the current limiting resistor and the light-emitting diode, and the LED light is always on. Control the controller through the temperature adjustment button to make the heating power stable within the specified range. If there is electric leakage or short circuit in the system, the fuse of the buzzer melts and the buzzer alarms.

[0041] The straight cylinder is constructed by two semi-cylindrical cylinders of 304 stainless steel, and a layer of heat insulation cotton 106 is wrapped outside it. The two semi-cylindrical cylinders are connected by hinges, and the other side is connected by a rotating shaft buckle. Before use, first open the straight cylinder and put it on the pipeline to be heated. After placing it in position, connect the rotating shaft buckle. Make the vacuum drying and dehumidification device fixed on the pipeline, connect the 220v maintenance power supply, and then the ice removal and dehumidification work can be started.

[0042] This device solves the problems that the ice in the VDS hose cannot be taken out and the vacuum pumping efficiency is reduced; long-term heating can also increase the evaporation amount of moisture in the pipeline, accelerate the vacuum pumping rate, reduce the exposure time of personnel by the time protection method, and reduce the collective dose of the operation team.

[0043] The above embodiments only illustrate the implementation manners of the present utility model, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation to the scope of the utility model patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made, and these all fall within the protection scope of the present utility model.

Claims

1. A vacuum drying and dehumidification device for spent fuel dry storage, comprising a VDS system (2) and a vacuum pump (3), characterized in that: The VDS system (2) and the vacuum pump (3) are both arranged on a fixed frame, and the VDS hose on the VDS system (2) is equipped with a heating vacuum drying and dehumidifying device (1) for heating the VDS hose; The heating vacuum drying dehumidification device (1) comprises a stainless steel straight cylinder (102) consisting of two semi-cylindrical cylinders, the two semi-cylindrical cylinders are connected by a hinge (101), and the two semi-cylindrical cylinders are fixed by a rotating shaft buckle (105); A controller (104) is installed on the top of the heating vacuum drying dehumidification device (1), an electric wire (107) is connected to the controller (104), and a display (103) is installed on the top of the controller (104); The inner side of the stainless steel straight cylinder (102) is provided with heat-insulating cotton (106), the inner side of the heat-insulating cotton (106) is provided with a heating wire (108), and the inner side of the heat-insulating cotton (106) is also provided with a patch-type temperature sensor.

2. The vacuum drying and dehumidification device for spent fuel dry storage according to claim 1 is characterized in that: The controller (104) is mounted on the heating vacuum drying dehumidification device (1) by means of screws, and the display (103) is mounted on the controller (104) by means of screws.

3. The vacuum drying and dehumidification device for spent fuel dry storage according to claim 2 is characterized in that: The display (103) is composed of a switch button, a temperature adjustment button, a display screen, a buzzer and an LED indicator light.

4. The vacuum drying and dehumidification device for spent fuel dry storage according to claim 1 is characterized in that: The controller (104) is connected to an external power source via an electric wire (107).

5. The vacuum drying and dehumidification device for spent fuel dry storage according to claim 1 is characterized in that: The heating wire (108) is electrically connected to the controller (104), and the controller (104) is electrically connected to the display (103).

6. The vacuum drying and dehumidification device for spent fuel dry storage according to claim 1 is characterized in that: The display (103) is electrically connected to the patch-type temperature sensor via a controller (104).

7. The vacuum drying and dehumidification device for spent fuel dry storage according to claim 1 is characterized in that: The heating wire (108) is made of nickel-chromium wire wrapped with high-strength polyester paint, and is evenly wound on the asbestos wire core using a spiral winding process, and is distributed in an S-shape on both sides of the interior of the stainless steel straight cylinder (102).

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