Liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 and temperature control method

Abstract

The invention relates to a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 and a temperature control method.The thermostat comprises a rack, a liquid nitrogen bin arranged on the upper portion of the rack, a temperature control box arranged on the lower portion of the rack and at least two liquid nitrogen temperature control devices arranged in the temperature control box, and each liquid nitrogen temperature control device comprises a closed cold trap; the device comprises a cold trap, a liquid nitrogen bin arranged in the cold trap, a sample coil pipe arranged in the cold trap, a liquid nitrogen channel pipe arranged in the center of the sample coil pipe and communicated with the liquid nitrogen bin and the cold trap, a heating device arranged in the cold trap, and a sample temperature measuring device, a plurality of liquid nitrogen inlets and a plurality of liquid nitrogen outlets are formed in the positions, corresponding to the liquid nitrogen bin and the cold trap, of the liquid nitrogen channel pipe respectively, and a temperature control rod for opening or closing the liquid nitrogen inlets and the liquid nitrogen outlets is arranged in the liquid nitrogen channel pipe. The device is provided with a plurality of gaseous effluent passages, and the passages are independently subjected to temperature control and do not interfere with one another, so that the working efficiency is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of temperature control, and in particular relates to a liquid nitrogen thermostat for monitoring Kr-85 gaseous effluent and a temperature control method. Background Art

[0002] In the radiation protection monitoring of nuclear power plant facilities and nuclear fuel reprocessing plants, the content of Kr-85 in gaseous effluents needs to be monitored and analyzed. In the process of monitoring and analysis, the Kr-85 nuclide in the gaseous effluent first needs to be extracted by adsorption, and then it needs to be analyzed before it can be finally measured. The adsorption of Kr-85 nuclide can only ensure a good adsorption effect when the sample temperature reaches -196°C, and the analysis requires a temperature of up to 200°C, which requires the collected gaseous effluent to be heated and cooled in advance. Therefore, the thermostat is an indispensable part of the Kr-85 content monitoring device in the gaseous effluent.

[0003] At present, in order to avoid the interference between multiple gaseous effluent passages when running at the same time, which leads to the defect of unstable temperature control, the thermostat set in the existing gaseous effluent Kr-85 monitoring equipment is usually single-channel. Although it has good temperature control stability, its efficiency is very low. Therefore, how to design the structure of the liquid nitrogen thermostat for gaseous effluent Kr-85 monitoring to ensure that the passages do not interfere with each other when adding gaseous effluent passages is crucial to improving the efficiency of Kr-85 monitoring. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85, which has multiple gaseous effluent passages, and each passage is independently temperature controlled without interfering with each other, thereby greatly improving work efficiency.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 comprises a frame, a liquid nitrogen bin arranged on the upper part of the frame, a temperature control box arranged on the lower part of the frame, and at least two liquid nitrogen temperature control devices arranged in the temperature control box, wherein the liquid nitrogen temperature control device comprises a closed cold trap, a sample coil arranged in the cold trap, a liquid nitrogen channel pipe arranged at the center of the sample coil and connecting the liquid nitrogen bin and the cold trap, a heating device arranged in the cold trap, and a sample temperature measuring device, wherein the liquid nitrogen channel pipe is respectively provided with a plurality of liquid nitrogen inlets and a plurality of liquid nitrogen outlets at positions corresponding to the liquid nitrogen bin and the cold trap, and a temperature control rod for opening or closing the liquid nitrogen inlet and the liquid nitrogen outlet is arranged in the liquid nitrogen channel pipe.

[0007] As a further technical solution, the warehouse wall of the liquid nitrogen warehouse is a double-wall structure with a vacuum cavity, and the top of the liquid nitrogen warehouse is provided with a vacuum exhaust port connected to the temperature control box and a pressure relief valve connected to the liquid nitrogen warehouse.

[0008] As a further technical solution, the vacuum suction port is connected to a vacuum pump through a pipeline, and a gate valve is provided on the vacuum suction port.

[0009] As a further technical solution, the sample temperature measuring device includes an outer sleeve and a temperature sensor arranged in the outer sleeve; the position of the outer sleeve corresponds to a cold trap, and the sensing end of the temperature sensor is arranged in the corresponding cold trap.

[0010] As a further technical solution, the top of the outer sleeve extends out of the liquid nitrogen tank;

[0011] As a further technical solution, a liquid nitrogen inlet is also provided on the top of the liquid nitrogen bin.

[0012] As a further technical solution, two ends of the sample coil are respectively extended out of the temperature control box to be provided with a sample inlet and a sample outlet.

[0013] As a further technical solution, the heating device adopts an electric heating tube or an electric heating wire.

[0014] As a further technical solution, the temperature control rod opens or closes the liquid nitrogen inlet or liquid nitrogen outlet by sliding up and down;

[0015] As a further technical solution, the top of the temperature control rod extends to the outside of the liquid nitrogen tank.

[0016] As a further technical solution, a radiation protection layer is arranged outside the cold trap.

[0017] As a further technical solution, a driving device for controlling the up and down sliding and sliding distance of the temperature control rod is provided at the top of the temperature control rod;

[0018] As a further technical solution, the temperature control rod also includes a temperature controller, which is respectively communicatively connected with the driving device and heating device of the two liquid nitrogen temperature control devices and the temperature sensor of the sample temperature measuring device.

[0019] A method for controlling the temperature of the gaseous effluent Kr-85 by using a liquid nitrogen thermostat comprises the following steps:

[0020] Step 1. Before starting the liquid nitrogen thermostat for monitoring gaseous effluent Kr-85, first add liquid nitrogen into the liquid nitrogen tank from the liquid nitrogen inlet and cover the cover; connect the vacuum port and the vacuum device, open the plug valve, vacuum the vacuum chamber, and close the plug valve after the vacuum is completed; insert a temperature sensor into the outer sleeve to measure the temperature of the sample;

[0021] Step 2, connecting the gaseous effluent Kr-85 monitoring liquid nitrogen thermostat with the temperature controller through a data line communication, and controlling the sliding of the temperature control rod on the gaseous effluent Kr-85 monitoring liquid nitrogen thermostat and the start and stop of the heating device through the temperature controller;

[0022] Step 3, at least one sample coil in the liquid nitrogen thermostat for monitoring the gaseous effluent Kr-85 is connected to the gaseous effluent pipeline of the monitoring device; when the sample temperature is cooled to -196 degrees Celsius, the temperature controller controls the driving device of the liquid nitrogen temperature control device to operate, so that the temperature control rod rises, and the liquid nitrogen outlet and part or all of the liquid nitrogen inlets on the liquid nitrogen channel tube are opened, so that the liquid nitrogen in the liquid nitrogen warehouse flows into the cold trap through the liquid nitrogen pipeline to cool the sample; when the sample needs to be heated to 200 degrees Celsius, the temperature controller controls the temperature control rod to descend, closes all liquid nitrogen inlets and liquid nitrogen outlets, and then controls the heating device to open, the liquid nitrogen in the cold trap is vaporized, and the sample is heated. When the sample is heated to 200 degrees Celsius, the temperature controller controls the opening and closing of the heating device to achieve 200 degrees Celsius insulation.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention arranges the cold trap of the liquid nitrogen temperature control device below the liquid nitrogen bin and communicates with the cold trap through a liquid nitrogen channel pipe, and realizes the independent operation of multiple liquid nitrogen temperature control devices through a temperature control rod, thereby greatly improving the work efficiency.

[0025] 2. The present invention is provided with a vacuum exhaust port connected to the temperature control box. By evacuating the temperature control box to make the interior of the box in a vacuum state, the vacuum insulation principle is utilized to achieve thermal insulation between cold traps, thereby avoiding mutual influence between cold traps. When multiple liquid nitrogen temperature control devices are running at the same time, mutual interference is avoided, thereby ensuring the stability of temperature control.

[0026] 3. The liquid nitrogen warehouse adopts a vacuum double-wall structure, the cold trap is covered with a radiation-proof layer, and the gaseous distillate pipeline of the monitoring device is connected to the sample inlet and sample outlet of the sample coil through a KF25 clamp with an O-ring, with strong overall sealing and shielding properties.

[0027] 4. The present invention also provides a temperature controller, which controls the operation of the driving device and the heating device according to the set temperature and the program to achieve temperature control of the sample. The temperature controller has a high degree of automation, a relatively stable operation process, and a good use effect.

[0028] In summary, the present invention has a small size, strong sealing and shielding properties, a firm structure, can monitor gaseous effluent Kr-85 in multiple channels simultaneously, improves work efficiency, can automatically perform temperature control, is easy to operate, runs stably, and has good use effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a front view of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 in one embodiment of the present invention;

[0030] Figure 2 A perspective view of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 in one embodiment of the present invention;

[0031] Figure 3 It is a schematic diagram of the structure of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 in one embodiment of the present invention;

[0032] Figure 4 A three-dimensional diagram of a sample coil in one embodiment of the present invention;

[0033] Figure 5 This is a temperature control principle diagram of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 in one embodiment of the present invention;

[0034] In the figure: 1. rack, 2. liquid nitrogen bin, 3. temperature control box, 4. liquid nitrogen temperature control device, 5. cold trap, 6. sample coil, 7. liquid nitrogen channel tube, 8. heating device, 9. liquid nitrogen inlet, 10. liquid nitrogen outlet, 11. temperature control rod, 12. vacuum chamber, 13. vacuum exhaust port, 14. vent valve, 15. plug valve, 16. outer sleeve, 17. liquid nitrogen inlet, 18. temperature sensor, 19. sample inlet, 20. sample outlet, 21. driving device; 22. temperature controller. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] The present invention is described in further detail below with reference to the accompanying drawings.

[0039] Example 1

[0040] Figure 1-4 An embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention is shown, comprising a frame 1, a liquid nitrogen bin 2 arranged on the upper part of the frame 1, a temperature control box 3 arranged at the lower part of the frame 1, and at least two liquid nitrogen temperature control devices 4 arranged in the temperature control box 3, wherein the liquid nitrogen temperature control device 4 comprises a closed cold trap 5, a sample coil 6 arranged in the cold trap 5, a liquid nitrogen channel tube 7 arranged at the center of the sample coil 6 and connecting the liquid nitrogen bin and the cold trap 5, a heating device 8 arranged in the cold trap 5, and a sample temperature measuring device, wherein the liquid nitrogen channel tube 7 is provided with a plurality of liquid nitrogen inlets 9 and a plurality of liquid nitrogen outlets 10 at positions corresponding to the liquid nitrogen bin and the cold trap 5, respectively, and a temperature control rod 11 for opening or closing the liquid nitrogen inlet 9 and the liquid nitrogen outlet 10 is provided in the liquid nitrogen channel tube 7. The present invention arranges a cold trap of a liquid nitrogen temperature control device below a liquid nitrogen bin and communicates with the cold trap through a liquid nitrogen channel pipe, and realizes independent operation of a plurality of liquid nitrogen temperature control devices through a temperature control rod, thereby greatly improving work efficiency.

[0041] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, a plurality of liquid nitrogen inlets 9 and a plurality of liquid nitrogen outlets 10 are evenly arranged from top to bottom in a plurality of circles, and a plurality of liquid nitrogen outlets 10 are evenly arranged along the circumference in each circle. The liquid nitrogen outlets 10 of the present invention are evenly arranged from top to bottom in a plurality of circles, and a plurality of liquid nitrogen outlets 10 are evenly arranged along the circumference in each circle, which can ensure that the liquid nitrogen is evenly in contact with the sample coil 6 when it flows out, and improve the consistency of the temperature of each part of the sample coil 6. The liquid nitrogen inlet 9 is evenly arranged from top to bottom in a plurality of circles, and a plurality of liquid nitrogen outlets 10 are evenly arranged along the circumference in each circle, and the number of liquid nitrogen inlets 9 opened can be controlled by controlling the insertion depth of the temperature control rod 11, thereby controlling the flow rate of liquid nitrogen entering the liquid nitrogen channel tube 7, thereby controlling the cooling rate of the sample.

[0042] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, the warehouse wall of the liquid nitrogen warehouse 2 is a double-walled structure with a vacuum cavity 12, and the top of the liquid nitrogen warehouse 2 is provided with a vacuum exhaust port 13 connected to the temperature control box 3 and a pressure relief valve 14 connected to the liquid nitrogen warehouse 2. The present invention is provided with a vacuum exhaust port connected to the temperature control box 3, and the temperature control box is evacuated to make the interior thereof in a vacuum state, thereby utilizing the vacuum insulation principle to achieve thermal insulation between cold traps, avoiding mutual influence between cold traps, and avoiding mutual interference when multiple liquid nitrogen temperature control devices are running at the same time, thereby ensuring the stability of temperature control. The pressure relief valve is provided to adjust the pressure of the liquid nitrogen warehouse to prevent safety accidents caused by excessive pressure.

[0043] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, the vacuum exhaust port 13 is connected to a vacuum pump through a pipeline, and a gate valve 15 is provided on the vacuum exhaust port 13.

[0044] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, the sample temperature measuring device includes an outer sleeve 16, and a temperature sensor 18 arranged in the outer sleeve 16 for measuring the temperature of the sample; the position of the outer sleeve 16 corresponds to the cold trap 5, and the sensing end of the temperature sensor 18 is arranged in the corresponding cold trap 5.

[0045] The top of the outer sleeve 16 extends out of the liquid nitrogen tank 2;

[0046] A liquid nitrogen inlet 17 is also provided on the top of the liquid nitrogen warehouse 2 .

[0047] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, two ends of the sample coil 6 extend out of the temperature control box 3 and are provided with a sample inlet 19 and a sample outlet 20 respectively.

[0048] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, the heating device 8 adopts an electric heating tube or an electric heating wire.

[0049] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, the temperature control rod 11 opens or closes the liquid nitrogen inlet 9 or the liquid nitrogen outlet 10 by sliding up and down.

[0050] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, the top of the temperature control rod 11 extends to the outside of the liquid nitrogen warehouse 2.

[0051] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, a radiation protection layer is arranged outside the cold trap 5 .

[0052] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, the top of the temperature control rod is provided with a driving device 21 for controlling its up and down sliding and sliding distance;

[0053] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, the driving device 21 adopts an electric telescopic rod or a cylinder.

[0054] As an embodiment of the liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, it also includes a temperature controller 22, such as Figure 5 As shown, the temperature controller 22 is respectively connected to the driving device 21 and the heating device 8 of the two liquid nitrogen temperature control devices 4 and the temperature sensor 18 of the sample temperature measuring device. The device is used in conjunction with the temperature controller 22, and the temperature is controlled by the temperature controller 22 to operate, with a high degree of automation, a relatively stable operation process, and a good use effect.

[0055] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, the liquid nitrogen inlet 17 and the outer sleeve 16 are both provided with a cover plate, which is used for sealing when not in use.

[0056] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, the temperature controller adopts a temperature controller with a programmable PLC control system.

[0057] As an embodiment of a liquid nitrogen thermostat for monitoring Kr-85 of gaseous effluent of the present invention, the liquid nitrogen tank, temperature control tank, cold trap and temperature control rod of the liquid nitrogen thermostat for monitoring Kr-85 of gaseous effluent are all made of SUS304 material, the diameter of the present invention is 432mm and the height is 498mm; the supporting bracket is made of 40mm×40mm aluminum alloy profile, 540mm long, 540mm wide and 815mm high, and its volume is small and the structure is firm;

[0058] As an embodiment of a liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 of the present invention, the sample inlet 19 and the sample outlet 20 are connected to the gaseous effluent pipeline of the monitoring device through a clamp KF25 with an O-ring.

[0059] As an embodiment of a liquid nitrogen thermostat for monitoring Kr-85 in gaseous effluent of the present invention, modified activated carbon is arranged in the sample coil 6, which can adsorb Kr-85 nuclides in the gaseous effluent at -196 degrees Celsius, and Kr-85 nuclides are decomposed from the activated carbon at 200 degrees Celsius.

[0060] Example 2

[0061] A method for controlling the temperature of the gaseous effluent Kr-85 monitoring liquid nitrogen thermostat described in Example 1, comprising the following steps:

[0062] Step 1: Before starting the liquid nitrogen thermostat for monitoring gaseous effluent Kr-85, first add liquid nitrogen into the liquid nitrogen bin 2 from the liquid nitrogen inlet 17 and cover the cover; connect the vacuum port to the vacuum device, open the gate valve 15, vacuum the vacuum chamber 12, and close the gate valve 15 after the vacuum is completed; insert the temperature sensor 18 into the outer sleeve 16 to measure the temperature of the sample coil 6;

[0063] Step 2, connecting the gaseous effluent Kr-85 monitoring liquid nitrogen thermostat with the temperature controller 22 through a data line communication, and controlling the sliding of the temperature control rod 11 on the gaseous effluent Kr-85 monitoring liquid nitrogen thermostat and the start and stop of the heating device 8 through the temperature controller 22;

[0064] Step 3, at least one sample coil 6 in the liquid nitrogen thermostat for monitoring the gaseous effluent Kr-85 is connected to the gaseous effluent pipeline of the monitoring device; when the sample temperature drops to -196 degrees Celsius, the temperature controller 22 controls the driving device 21 of the liquid nitrogen temperature control device 4 to operate, so that the temperature control rod 11 rises, opens the liquid nitrogen outlet 10 and part or all of the liquid nitrogen inlet 9 on the liquid nitrogen channel tube 7, and allows the liquid nitrogen in the liquid nitrogen warehouse to flow into the cold trap 5 through the liquid nitrogen pipeline (at the same time, the liquid nitrogen during the last heating The vaporized nitrogen is discharged into the liquid nitrogen bin through the liquid nitrogen channel tube 7, and finally discharged through the liquid nitrogen inlet or the pressure relief valve) to cool the sample; when the sample needs to be heated to 200 degrees Celsius, the temperature controller 22 controls the temperature control rod 11 to descend, closes all the liquid nitrogen inlets 9 and the liquid nitrogen outlets 10, and then controls the heating device 8 to open, the liquid nitrogen in the cold trap 5 is vaporized, and the sample is heated. When the sample is heated to 200 degrees Celsius, the temperature controller 22 controls the opening and closing of the heating device 8 to achieve 200 degrees Celsius insulation.

[0065] The present invention arranges the cold trap 5 of the liquid nitrogen temperature control device 4 below the liquid nitrogen bin 2, and communicates with the cold trap 5 through the liquid nitrogen channel pipe 7, so that the temperature control of multiple liquid nitrogen temperature control devices 4 is realized separately, which greatly improves the working efficiency. The liquid nitrogen bin 2 adopts a vacuum double-wall structure, the cold trap 5 is coated with a radiation protection layer, and the gaseous distillate pipeline of the monitoring device is connected to the sample inlet 19 and the sample outlet 20 of the sample coil 6 through a KF25 clamp with an O-ring, and the overall sealing and shielding properties are strong. In addition, the present invention further arranges a temperature controller 22, and the temperature controller 22 controls the operation of the driving device 21 and the heating device 8 according to the set temperature and the program to realize the temperature control of the sample, and the automation degree is high, the operation process is relatively stable, and the use effect is good.

[0066] The above-described embodiments are only preferred embodiments of the present invention, and are not exhaustive of the feasible implementations of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A liquid nitrogen thermostat for monitoring gaseous effluent Kr-85, characterized in that: The invention comprises a frame (1), a liquid nitrogen bin (2) arranged on the upper part of the frame (1), a temperature control box (3) arranged on the lower part of the frame (1), and at least two liquid nitrogen temperature control devices (4) arranged in the temperature control box (3), wherein the liquid nitrogen temperature control device (4) comprises a closed cold trap (5), a sample coil (6) arranged in the cold trap (5), a liquid nitrogen channel tube (7) arranged at the center of the sample coil (6) and connecting the liquid nitrogen bin and the cold trap (5), a heating device (8) arranged in the cold trap (5), and a sample temperature measuring device, wherein the liquid nitrogen channel tube (7) is provided with a plurality of liquid nitrogen inlets (9) and a plurality of liquid nitrogen outlets (10) at positions corresponding to the liquid nitrogen bin and the cold trap (5), respectively, and a temperature control rod (11) is arranged in the liquid nitrogen channel tube (7) for opening or closing the liquid nitrogen inlet (9) and the liquid nitrogen outlet (10).

2. The liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 according to claim 1, characterized in that: The liquid nitrogen warehouse (2) has a double-wall structure with a vacuum chamber (12). The top of the liquid nitrogen bin (2) is provided with a vacuum exhaust port (13) connected to the temperature control box (3) and a pressure relief valve (14) connected to the liquid nitrogen bin (2).

3. The liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 according to claim 2, characterized in that: The vacuum suction port (13) is connected to a vacuum pump via a pipeline, and a gate valve (15) is provided on the vacuum suction port (13).

4. The liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 according to claim 1, characterized in that: The sample temperature measuring device comprises an outer sleeve (16) and a temperature sensor (18) arranged in the outer sleeve (16); the position of the outer sleeve (16) corresponds to the cold trap (5), and the sensing end of the temperature sensor (18) is arranged in the corresponding cold trap (5); The top of the outer sleeve (16) extends out of the liquid nitrogen tank (2); The top of the liquid nitrogen warehouse (2) is also provided with a liquid nitrogen inlet (17).

5. The liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 according to claim 1, characterized in that: The two ends of the sample coil (6) extend out of the temperature control box (3) and are provided with a sample inlet (19) and a sample outlet (20).

6. The liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 according to claim 1, characterized in that: The heating device (8) adopts an electric heating tube or an electric heating wire.

7. The liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 according to claim 1, characterized in that: The temperature control rod (11) opens or closes the liquid nitrogen inlet (9) or the liquid nitrogen outlet (10) by sliding up and down; The top of the temperature control rod (11) extends to the outside of the liquid nitrogen warehouse (2).

8. The liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 according to claim 1, characterized in that: A radiation protection layer is arranged outside the cold trap (5).

9. The liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 according to claim 1, characterized in that: The top of the temperature control rod (11) is provided with a driving device (21) for controlling its up and down sliding and sliding distance; The temperature control rod (11) further comprises a temperature controller (22), and the temperature controller (22) is respectively connected to the driving devices (21) and the heating devices (8) of the two liquid nitrogen temperature control devices (4) and the temperature sensor (18) of the sample temperature measuring device.

10. A method for temperature control using a liquid nitrogen thermostat for monitoring Kr-85 of gaseous effluent according to any one of claims 1 to 9, characterized in that: The steps include: Step 1: Before starting the liquid nitrogen thermostat for monitoring gaseous effluent Kr-85, first add liquid nitrogen into the liquid nitrogen bin (2) from the liquid nitrogen inlet (17) and cover the cover; The vacuum port and the vacuum device are connected, and the gate valve (15) is opened to vacuumize the vacuum chamber (12). After the vacuuming is completed, the gate valve (15) is closed; a temperature sensor (18) is inserted into the outer sleeve to measure the temperature of the sample; Step 2, connecting the gaseous effluent Kr-85 monitoring liquid nitrogen thermostat to the temperature controller (22) via a data line communication, and controlling the sliding of the temperature control rod (11) on the gaseous effluent Kr-85 monitoring liquid nitrogen thermostat and the start and stop of the heating device (8) via the temperature controller (22); Step 3: connect at least one sample coil (6) in the liquid nitrogen thermostat for monitoring gaseous effluent Kr-85 to the gaseous effluent pipeline of the monitoring device; when the sample temperature drops to -196 degrees Celsius, the temperature controller (22) controls the driving device (21) of the liquid nitrogen temperature control device (4) to operate, so that the temperature control rod (11) rises, opens the liquid nitrogen outlet (10) and part or all of the liquid nitrogen inlet (9) on the liquid nitrogen channel tube (7), and allows the liquid nitrogen in the liquid nitrogen tank to The liquid nitrogen flows into the cold trap (5) through the liquid nitrogen pipeline to cool the sample; when the sample needs to be heated to 200 degrees Celsius, the temperature controller (22) controls the temperature control rod (11) to descend, closes all the liquid nitrogen inlets (9) and liquid nitrogen outlets (10), and then controls the heating device (8) to open, the liquid nitrogen in the cold trap (5) vaporizes, and the sample is heated. When the sample is heated to 200 degrees Celsius, the temperature controller (22) controls the opening and closing of the heating device (8) to achieve 200 degrees Celsius insulation.

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