Helium low-temperature circulating system for deuterium-tritium fusion device

Abstract

The invention relates to a helium low-temperature circulating system for a deuterium-tritium fusion device. The helium low-temperature circulating system comprises a first heat exchanger, a second heat exchanger, a third heat exchanger, a fifth heat exchanger and a first compressor, a high-temperature helium pipe is connected with a first inlet of the first heat exchanger, a first outlet of the first heat exchanger is connected with an inlet of the first compressor, an outlet of the first compressor is connected with an inlet of the fifth heat exchanger, and an outlet of the fifth heat exchanger is connected with a second inlet of the first heat exchanger. A second outlet of the first heat exchanger is connected with a first inlet of the second heat exchanger, a first outlet of the second heat exchanger is connected with an inlet of the third heat exchanger, and an outlet of the third heat exchanger is connected with a low-temperature helium pipe. According to the helium low-temperature circulating system for the deuterium-tritium fusion device, through the combined action of the multi-stage heat exchanger and the compressor, stable 80K temperature zone helium active cooling supply is provided for a deuterium-tritium fusion reactor.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration technology, and in particular to a helium low-temperature circulation system for a deuterium-tritium fusion device. Background Art

[0002] As people's demand for energy continues to grow, controlled nuclear fusion is seen as a solution to future clean energy. Its principle is to simulate the nuclear fusion process inside the sun, releasing huge amounts of energy by fusing light atomic nuclei (such as deuterium and tritium) under extremely high temperature and high pressure environments.

[0003] To ensure the stable operation of the fusion device, it is necessary to provide active cooling in the 80K temperature zone for all components of the fusion reactor device equipped with cold shields, including: internal and external cold shields of the deuterium-tritium fusion reactor main unit, vacuum chamber cryopump, NBI cryopump, feeder cold shield, cryogenic distribution valve box, cryogenic transmission pipeline and other components.

[0004] However, due to the extremely penetrating high-energy neutrons produced by deuterium-tritium (DT) fusion reactions, using traditional liquid nitrogen as a cooling medium would cause activation of the high-energy neutrons with nitrogen nuclei, producing radioactive isotopes. This would contaminate the cooling circuit and affect system lifespan and maintenance. Therefore, to avoid nitrogen activation issues, helium has become an ideal cooling medium: its inert monatomic properties prevent it from reacting with neutrons, thus preventing radioactive contamination; it remains stable in the 80 K temperature range, meeting cryogenic cooling requirements without the risk of phase transitions; it has excellent material compatibility and does not corrode mechanical structural materials; and, if helium leaks, it can be easily purified and recovered, resulting in low maintenance costs and meeting the long-term operation requirements of fusion reactors.

[0005] Therefore, a stably operating helium low-temperature circulation system for a deuterium-tritium fusion device is provided. Summary of the Invention

[0006] To address the above technical issues, the present invention provides a helium cryogenic circulation system for a deuterium-tritium fusion device. This cryogenic circulation system provides stable helium cooling at 80K for the fusion reactor through the coordinated action of a multi-stage heat exchanger and a compressor.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A helium low-temperature circulation system for a deuterium-tritium fusion device, comprising a first heat exchanger, a second heat exchanger, a third heat exchanger, a fifth heat exchanger and a first compressor;

[0009] A high-temperature helium gas pipe is connected to the first inlet of the first heat exchanger, the first outlet of the first heat exchanger is connected to the inlet of the first compressor, the outlet of the first compressor is connected to the inlet of the fifth heat exchanger, the outlet of the fifth heat exchanger is connected to the second inlet of the first heat exchanger, the second outlet of the first heat exchanger is connected to the first inlet of the second heat exchanger, the first outlet of the second heat exchanger is connected to the inlet of the third heat exchanger, and the outlet of the third heat exchanger is connected to the low-temperature helium gas pipe.

[0010] Wherein, the third heat exchanger is immersed in a liquid nitrogen tank.

[0011] In which, the helium low-temperature circulation system for the deuterium-tritium fusion device also includes a liquid nitrogen reliquefaction device, which includes a second compressor, a sixth heat exchanger, a fourth heat exchanger, an expander and a second gas-liquid separator, wherein the outlet of the liquid nitrogen tank is connected to the inlet of the second compressor, the outlet of the second compressor is connected to the inlet of the sixth heat exchanger, the outlet of the sixth heat exchanger is connected to the second inlet of the fourth heat exchanger, the second outlet of the fourth heat exchanger is connected to the inlet of the expander, the outlet of the expander is connected to the inlet of the second gas-liquid separator, and the first outlet of the second gas-liquid separator is connected to the first inlet of the liquid nitrogen tank.

[0012] Preferably, the second outlet of the second gas-liquid separator is connected to the first inlet of the fourth heat exchanger, and the first outlet of the fourth heat exchanger is connected to the inlet of the second compressor.

[0013] Preferably, the liquid nitrogen reliquefaction device further includes a first gas-liquid separator, the first outlet of the second gas-liquid separator is connected to the second inlet of the second heat exchanger, the second outlet of the second heat exchanger is connected to the inlet of the first gas-liquid separator, and the first outlet of the first gas-liquid separator is connected to the second inlet of the liquid nitrogen tank.

[0014] Preferably, the second outlet of the first gas-liquid separator is connected to the inlet of the second compressor.

[0015] Preferably, the temperature of the second outlet of the second heat exchanger is always higher than the dew point temperature of nitrogen at its pressure.

[0016] Preferably, a fourth regulating valve is provided between the first outlet of the second gas-liquid separator and the second inlet of the second heat exchanger, and the amount of liquid nitrogen flowing through the second inlet of the second heat exchanger is regulated by adjusting the fourth regulating valve.

[0017] The cryogenic pump return pipe is connected to the third inlet of the first heat exchanger, and the third outlet of the first heat exchanger is connected to the inlet of the first compressor.

[0018] Preferably, the fifth heat exchanger and the sixth heat exchanger are water-cooled heat exchangers.

[0019] The beneficial effects of the present invention are as follows:

[0020] (1) The helium low-temperature circulation system for the deuterium-tritium fusion device of the present invention provides a stable 80K temperature range helium active cooling supply for the fusion reactor through the combined action of a multi-stage heat exchanger and a compressor.

[0021] (2) The helium cryogenic circulation system for the deuterium-tritium fusion device of the present invention uses helium as a cooling medium to avoid neutron activation contamination through the synergistic effect of a multi-stage heat exchanger, a compressor and a liquid nitrogen reliquefaction device, and integrates cold recovery and nitrogen reliquefaction functions, thereby significantly improving the cooling efficiency and energy utilization rate, and is suitable for the long-term reliable operation of a deuterium-tritium fusion reactor.

[0022] (3) The helium cryogenic circulation system for the deuterium-tritium fusion device of the present invention dynamically adjusts the liquid nitrogen flow rate to maintain the system temperature stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the overall structure of the helium low-temperature circulation system for the deuterium-tritium fusion device of the present invention.

[0024] The figures are marked as follows: 1-first heat exchanger; 1A-first inlet of the first heat exchanger; 1B-first outlet of the first heat exchanger; 1C-second inlet of the first heat exchanger; 1D-second outlet of the first heat exchanger; 1E-third inlet of the first heat exchanger; 1F-third outlet of the first heat exchanger; 2-second heat exchanger; 2A-first outlet of the second heat exchanger; 2B-first inlet of the second heat exchanger; 2C-second inlet of the second heat exchanger; 2D-second outlet of the second heat exchanger; 3-third heat exchanger; 3A-inlet of the third heat exchanger; 3B-outlet of the third heat exchanger; 4-first gas-liquid separator; 4A-second outlet of the first gas-liquid separator; 4B-first outlet of the first gas-liquid separator; 5-liquid nitrogen tank; 5A-first inlet of the liquid nitrogen tank; 5B-second inlet of the liquid nitrogen tank; 5C-outlet of the liquid nitrogen tank; 6-second gas-liquid separator; 6A-second gas-liquid separator The first outlet of the gas-liquid separator; 6B-the second outlet of the second gas-liquid separator; 7-the fourth heat exchanger; 7A-the first inlet of the fourth heat exchanger; 7B-the first outlet of the fourth heat exchanger; 7C-the second inlet of the fourth heat exchanger; 7D-the second outlet of the fourth heat exchanger; 8-the first compressor; 9-the fifth heat exchanger; 10-the second compressor; 11-the sixth heat exchanger; 12-the expander; V1-the first regulating valve; V2-the second regulating valve; V3-the third regulating valve; V4-the fourth regulating valve; V5-the fifth regulating valve; J1-the first throttle valve; J2-the second throttle valve; J3-the third throttle valve; J4-the fourth throttle valve. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0026] See also Figure 1 A helium low-temperature circulation system for a deuterium-tritium fusion device includes a first heat exchanger 1, a second heat exchanger 2, a third heat exchanger 3, a fifth heat exchanger 9 and a first compressor 8; a high-temperature helium pipe is connected to the first inlet 1A of the first heat exchanger, the first outlet 1B of the first heat exchanger is connected to the inlet of the first compressor 8, the outlet of the first compressor 8 is connected to the inlet of the fifth heat exchanger 9, the outlet of the fifth heat exchanger 9 is connected to the second inlet 1C of the first heat exchanger, the second outlet 1D of the first heat exchanger is connected to the first inlet 2B of the second heat exchanger, the first outlet 2A of the second heat exchanger is connected to the inlet 3A of the third heat exchanger, and the outlet 3B of the third heat exchanger is connected to the low-temperature helium pipe.

[0027] Preferably, the second heat exchanger 2 is made of stainless steel, the third heat exchanger 3 is a thermosiphon heat exchanger, and the fifth heat exchanger 9 and the sixth heat exchanger 11 are water-cooled heat exchangers.

[0028] Preferably, the high-temperature, low-pressure helium pipe is connected to the inlet of the first regulating valve V1, the outlet of the first regulating valve V1 is connected to the first inlet 1A of the first heat exchanger, the first outlet 1B of the first heat exchanger is connected to the inlet of the first compressor 8, the outlet of the first compressor 8 is connected to the inlet of the fifth heat exchanger 9, the outlet of the fifth heat exchanger 9 is connected to the second inlet 1C of the first heat exchanger, the second outlet 1D of the first heat exchanger is connected to the first inlet 2B of the second heat exchanger, the first outlet 2A of the second heat exchanger is connected to the inlet 3A of the third heat exchanger, the outlet 3B of the third heat exchanger is connected to the inlet of the second regulating valve V2, and the outlet of the second regulating valve V2 is connected to the low-temperature helium pipe to supply low-temperature, high-pressure helium.

[0029] The operation process is as follows: the 100K temperature range low-pressure helium supplied by the user end enters the first heat exchanger 1. After the cold recovery is completed in the heat exchanger, the helium temperature is raised to room temperature through the first outlet 1B of the first heat exchanger, and then enters the first compressor 8 through the inlet of the first compressor 8. The helium pressure is increased to the rated value through compression. In order to eliminate the temperature rise effect caused by the work compression of the helium by the first compressor 8, the high-pressure helium is cooled to room temperature through the cooling water of the fifth heat exchanger 9. The room temperature helium is then passed into the second inlet 1C of the first heat exchanger in the cold box and heat-exchanged to the 100K temperature range. It is then cooled to the 90K temperature range through the first inlet 2B of the second heat exchanger cooled by liquid nitrogen. The helium is then cooled to the 80K temperature range through the third heat exchanger 3 and transported back to the user end. This embodiment realizes the cooling of the 100K temperature range low-pressure helium to the 80K temperature range high-pressure helium through the above heat exchange process.

[0030] See also Figure 1 In one embodiment, the third heat exchanger 3 is immersed in the liquid nitrogen tank 5 to ensure the stability of the gas temperature at the outlet 3B of the third heat exchanger.

[0031] As a preferred embodiment, the helium low-temperature circulation system for the deuterium-tritium fusion device also includes a liquid nitrogen reliquefaction device, which includes a second compressor 10, a sixth heat exchanger 11, a fourth heat exchanger 7, an expander 12 and a second gas-liquid separator 6, wherein the outlet 5C of the liquid nitrogen tank is connected to the inlet of the second compressor 10, the outlet of the second compressor 10 is connected to the inlet of the sixth heat exchanger 11, the outlet of the sixth heat exchanger 11 is connected to the second inlet 7C of the fourth heat exchanger, the second outlet 7D of the fourth heat exchanger is connected to the inlet of the expander 12, the outlet of the expander 12 is connected to the inlet of the second gas-liquid separator 6, and the first outlet 6A of the second gas-liquid separator is connected to the first inlet 5A of the liquid nitrogen tank.

[0032] When the liquid nitrogen level in the liquid nitrogen tank 5 is too low, the high-temperature and high-pressure liquid nitrogen in the second gas-liquid separator 6 is throttled by the third throttle valve J3 and the low-temperature and low-pressure liquid nitrogen flows into the liquid nitrogen tank 5 .

[0033] As a preferred embodiment, the second outlet 6B of the second gas-liquid separator is connected to the first inlet 7A of the fourth heat exchanger, and the first outlet 7B of the fourth heat exchanger is connected to the inlet of the second compressor 10 .

[0034] See also Figure 1 The first outlet 6A of the second gas-liquid separator is connected to the inlet of the third throttle valve J3, and the outlet of the third throttle valve J3 is connected to the first inlet 5A of the liquid nitrogen tank.

[0035] The second outlet 6B of the second gas-liquid separator is connected to the inlet of the fifth regulating valve V5 , and the outlet of the fifth regulating valve V5 is connected to the first inlet 7A of the fourth heat exchanger.

[0036] Preferably, the liquid nitrogen reliquefaction apparatus further includes a first gas-liquid separator 4, a first outlet 6A of the second gas-liquid separator connected to the second inlet 2C of the second heat exchanger, a second outlet 2D of the second heat exchanger connected to the inlet of the first gas-liquid separator 4, and a first outlet 4B of the first gas-liquid separator connected to the second inlet 5B of the liquid nitrogen tank. This arrangement can cool the helium in the second heat exchanger.

[0037] The second outlet 2D of the second heat exchanger is connected to the inlet of the first gas-liquid separator 4. When the high-temperature and high-pressure liquid nitrogen level in the first gas-liquid separator 4 is too high, the low-temperature and low-pressure liquid nitrogen flows into the liquid nitrogen tank 5 after being throttled by the first throttle valve J1.

[0038] See also Figure 1 The first outlet 6A of the second gas-liquid separator is connected to the inlet of the fourth regulating valve V4, the outlet of the fourth regulating valve V4 is connected to the second inlet 2C of the second heat exchanger, the second outlet 2D of the second heat exchanger is connected to the inlet of the first gas-liquid separator 4, the first outlet 4B of the first gas-liquid separator is connected to the inlet of the first throttle valve J1, and the outlet of the first throttle valve J1 is connected to the second inlet 5B of the liquid nitrogen tank.

[0039] More preferably, the second outlet 4A of the first gas-liquid separator is connected to the inlet of the second throttle valve J2 , and the outlet of the second throttle valve J2 is connected to the inlet of the second compressor 10 .

[0040] The low-pressure nitrogen gas at the outlet of the second throttle valve J2, the outlet of the liquid nitrogen tank 5, and the first outlet 7B of the fourth heat exchanger is pressurized by the second compressor 10 to form high-temperature and high-pressure nitrogen gas. The gas is then cooled to room temperature by cooling water in the sixth heat exchanger 11 and connected to the second inlet 7C of the fourth heat exchanger. The gas is heat-exchanged by the fourth heat exchanger 7 to form low-temperature and high-pressure nitrogen gas. The gas is then expanded into low-temperature and low-pressure gas by the expander 12 and then throttled and cooled by the fourth throttle valve J4 before flowing into the second gas-liquid separator 6.

[0041] Preferably, the temperature of the second outlet 2D of the second heat exchanger is always higher than the dew point temperature of the nitrogen at its pressure. More preferably, a fourth regulating valve V4 is provided between the first outlet 6A of the second gas-liquid separator and the second inlet 2C of the second heat exchanger. By adjusting the fourth regulating valve V4, the amount of liquid nitrogen flowing through the second inlet 2C of the second heat exchanger is regulated. The required amount of liquid nitrogen is The value of is calculated from the cooling load required by the second heat exchanger 2.

[0042] Definition: Second heat exchanger hot end (helium): inlet temperature , inlet pressure , outlet temperature , outlet pressure , mass flow rate ;

[0043] Second heat exchanger cold end (liquid nitrogen): inlet temperature , inlet pressure , outlet temperature , outlet pressure , mass flow rate ;

[0044] By querying the physical property parameter database based on the inlet and outlet temperatures and pressures, the enthalpy values ​​at each point can be obtained as follows:

[0045] Second heat exchanger hot end (helium): inlet enthalpy , outlet enthalpy ;

[0046] Second heat exchanger cold end (liquid nitrogen): inlet enthalpy , outlet enthalpy ;

[0047] according to Calculate the cooling load required by the second heat exchanger 2;

[0048] but .

[0049] By adjusting the amount of liquid nitrogen flowing through the second inlet 2C of the second heat exchanger , control the temperature of the first outlet 2A of the second heat exchanger, that is, the inlet 3A of the third heat exchanger, to the rated value, while ensuring that the liquid level of the liquid nitrogen tank 5 remains stable, thereby ensuring that the temperature of the inlet 3A of the third heat exchanger and the outlet 3B of the third heat exchanger always remain at the rated value.

[0050] Because some of the helium transported by this system during the regeneration process of the cryopump in the deuterium-tritium fusion reactor will eventually flow into the helium recovery system of another system instead of returning to this system, this will cause certain flow fluctuations in this system. To avoid temperature fluctuations at the outlet 3B of the third heat exchanger, the amount of liquid nitrogen flowing through the second inlet 2C of the second heat exchanger must be regulated by adjusting the fourth regulating valve V4. The required amount of liquid nitrogen is calculated based on the required cooling load of the second heat exchanger 2. Therefore, the temperature of the second outlet 2D of the second heat exchanger is set to be always higher than the dew point temperature of nitrogen at its pressure. At the same time, the third throttle valve J3 is adjusted to control the liquid inflow to the first inlet 5A of the liquid nitrogen tank 5 to maintain a stable liquid level in the liquid nitrogen tank 5, thereby ensuring a stable temperature at the first outlet 2A of the second heat exchanger and, in turn, ensuring sufficient heat exchange and stable temperature output of the third heat exchanger 3.

[0051] In one embodiment, the cryogenic pump return pipe is connected to the third inlet 1E of the first heat exchanger, and the third outlet 1F of the first heat exchanger is connected to the inlet of the first compressor 8 .

[0052] The specific operation process is as follows: the return gas from the cryopump under the regeneration conditions of 4.5K and 80K enters the first heat exchanger 1 through the third regulating valve V3, and after heat exchange to room temperature, enters the first compressor 8 through the third outlet 1F of the first heat exchanger. This heat exchange process can retain more cooling capacity in the first heat exchanger 1, thereby lowering the outlet temperature of the second outlet 1D of the first heat exchanger and reducing the liquid nitrogen consumption of the second heat exchanger 2 and the third heat exchanger 3.

[0053] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0054] Portions not described in detail in this specification belong to the common knowledge in the art. The above examples are provided for the purpose of illustrating the present invention only and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. Various equivalent substitutions and modifications made without departing from the spirit and principles of the present invention are intended to be encompassed within the scope of the present invention.

Claims

1. A helium low temperature circulation system for a deuterium-tritium fusion device, characterized in that: comprising a first heat exchanger, a second heat exchanger, a third heat exchanger, a fifth heat exchanger and a first compressor; A high-temperature helium gas pipe is connected to the first inlet of the first heat exchanger, the first outlet of the first heat exchanger is connected to the inlet of the first compressor, the outlet of the first compressor is connected to the inlet of the fifth heat exchanger, the outlet of the fifth heat exchanger is connected to the second inlet of the first heat exchanger, the second outlet of the first heat exchanger is connected to the first inlet of the second heat exchanger, the first outlet of the second heat exchanger is connected to the inlet of the third heat exchanger, and the outlet of the third heat exchanger is connected to the low-temperature helium gas pipe.

2. The helium low-temperature circulation system for a deuterium-tritium fusion device according to claim 1, characterized in that: The third heat exchanger is immersed in the liquid nitrogen tank.

3. The helium low temperature circulation system for the deuterium-tritium fusion device according to claim 2, characterized in that: The helium low-temperature circulation system for the deuterium-tritium fusion device also includes a liquid nitrogen reliquefaction device, which includes a second compressor, a sixth heat exchanger, a fourth heat exchanger, an expander, and a second gas-liquid separator, wherein the outlet of the liquid nitrogen tank is connected to the inlet of the second compressor, the outlet of the second compressor is connected to the inlet of the sixth heat exchanger, the outlet of the sixth heat exchanger is connected to the second inlet of the fourth heat exchanger, the second outlet of the fourth heat exchanger is connected to the inlet of the expander, the outlet of the expander is connected to the inlet of the second gas-liquid separator, and the first outlet of the second gas-liquid separator is connected to the first inlet of the liquid nitrogen tank.

4. The helium cryogenic circulation system for a deuterium-tritium fusion device according to claim 3, characterized in that: The second outlet of the second gas-liquid separator is connected to the first inlet of the fourth heat exchanger, and the first outlet of the fourth heat exchanger is connected to the inlet of the second compressor.

5. The helium cryogenic circulation system for a deuterium-tritium fusion device according to any one of claims 2 to 4, characterized in that: The liquid nitrogen reliquefaction device also includes a first gas-liquid separator, a first outlet of the second gas-liquid separator is connected to the second inlet of the second heat exchanger, the second outlet of the second heat exchanger is connected to the inlet of the first gas-liquid separator, and the first outlet of the first gas-liquid separator is connected to the second inlet of the liquid nitrogen tank.

6. The helium cryogenic circulation system for a deuterium-tritium fusion device according to claim 5, characterized in that: The second outlet of the first gas-liquid separator is connected to the inlet of the second compressor.

7. The helium cryogenic circulation system for a deuterium-tritium fusion device according to claim 3, characterized in that: The temperature of the second outlet of the second heat exchanger is always higher than the dew point temperature of nitrogen at its pressure.

8. The helium cryogenic circulation system for a deuterium-tritium fusion device according to claim 3, characterized in that: A fourth regulating valve is provided between the first outlet of the second gas-liquid separator and the second inlet of the second heat exchanger, and the amount of liquid nitrogen flowing through the second inlet of the second heat exchanger is regulated by adjusting the fourth regulating valve.

9. The helium cryogenic circulation system for a deuterium-tritium fusion device according to claim 1, characterized in that: The cryogenic pump return pipe is connected to the third inlet of the first heat exchanger, and the third outlet of the first heat exchanger is connected to the inlet of the first compressor.

10. The helium low temperature circulation system for a deuterium-tritium fusion device according to claim 3, characterized in that: The fifth heat exchanger and the sixth heat exchanger are water-cooled heat exchangers.

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