Parallel multi-mode supercharged superfluid helium cryogenic system

Abstract

The utility model discloses a kind of parallel multi-mode pressurization superfluid helium cryogenic systems, 4.5K cold box connects room temperature compressor unit and 2K cold quantity acquisition module, for cooling high-pressure normal temperature helium to 4.5K;2K cold quantity acquisition module contains 2K phase separator, three-stage cold compressor unit, five-stage cold compressor unit etc., downstream branch conveys 2K temperature zone cold quantity to heat load module, and through low temperature, mixing, room temperature three parallel pressurization paths backflow normal temperature normal pressure helium;Heat load module simulates and verifies the cold quantity output of superfluid helium cryogenic system or user end cold quantity demand;Room temperature compressor unit compresses helium for 4.5K cold box.The system can switch pressurization mode according to heat load, avoid small load multi-pump group problem, guarantee large load stable operation, efficiently complete superfluid helium acquisition and circulation, give consideration to economy, flexibility and reliability, solve the problem that existing system adaptation is single, operation and maintenance cost is high and difficult to match heat load change.

Description

Technical Field

[0001] This utility model relates to cryogenic refrigeration, and more specifically to a parallel multi-mode pressurized superfluid helium cryogenic system. Background Technology

[0002] Superfluid helium is a key working fluid in the field of cryogenics, playing an irreplaceable role in major scientific and technological facilities such as cryogenic superconducting accelerators and high-end quantum detection devices. However, large-scale acquisition of stable superfluid helium relies on reliable, large-scale superfluid helium cryogenic systems. During the preparation of superfluid helium, to ensure the system reaches the target cooling temperature range (such as the commonly used 2K temperature range), the pressure within the superfluid helium pool must be maintained below the saturation pressure at the corresponding temperature at all times. Specifically, for a 2K temperature range superfluid helium system, the helium pool pressure must be controlled below 3.1 kPa. This is a core prerequisite for ensuring the stable existence of superfluid helium and the system's cooling performance.

[0003] In the thermodynamic cycle of a superfluid helium cryogenic system, a significant pressure rise gap exists: on the one hand, the absolute pressure at the inlet of the ambient temperature screw compressor in the liquid helium refrigeration loop is typically maintained at 1.0–1.2 bar; on the other hand, when the cryogenic helium flows through the JT (Joule-Thomson) negative pressure heat exchanger, the absolute pressure of the helium at the heat exchanger outlet drops below 3 kPa due to flow resistance. To solve this pressure difference problem and ensure normal helium circulation, a booster system with a total pressure ratio of 60–80 must be installed between the outlet of the JT negative pressure heat exchanger and the ambient temperature screw compressor.

[0004] Currently, the mainstream technical solutions in the industry for increasing the pressure ratio of cold helium can be divided into three categories.

[0005] First, the room temperature boosting mode. This method uses a room temperature pump set (Roots pump + backing mechanical pump set) as the core boosting component. Its advantages lie in its simple equipment structure, high technological maturity, and modular design of the Roots pump and mechanical pump, supporting disassembly and splicing, which can adapt to the variable operating conditions under low heat load. Furthermore, long-term operation verification in various cryogenic facilities in multiple countries has demonstrated that this method can achieve high stability of the superfluid helium pool pressure. However, because the pump inlet needs to be maintained at room temperature, and the cryogenic helium gas needs to be heated to room temperature before entering the pump set, the system's cold energy cannot be recovered, resulting in significant cold energy loss. Moreover, for low-load scenarios, a large number of pump sets are required to meet the boosting demand, leading to low system thermal efficiency. In addition, as the pump set operating time increases, the frequency of maintenance and repair will increase significantly, not only increasing operation and maintenance costs but also reducing the reliability of continuous system operation, resulting in poor overall energy consumption and operating economic benefits.

[0006] Second, the hybrid pressurization mode. This method employs a combination structure of a "low-temperature centrifugal compressor (cold compressor) + room temperature pump," where the cold end directly performs preliminary pressurization of the cold helium gas through 2-3 stages of centrifugal compressors. Compared to the pure room temperature pressurization mode, under the same heat load conditions, the number of room temperature pump units can be reduced. Simultaneously, the preliminary pressurization of the cold helium gas by the centrifugal compressors achieves partial cold energy recovery, which provides some benefit to improving the thermal efficiency and operational economy of the refrigeration system. However, the disadvantage of this method is still concentrated at the pump unit level of the room temperature pressurization stage. Similar to the pure room temperature pressurization mode, it fails to fundamentally solve the performance shortcomings caused by the room temperature pump.

[0007] Third, the cryogenic pressurization mode. This method uses a pure multi-stage centrifugal cold press as the sole pressurization component, directly pressurizing the cold helium gas throughout the entire process at a cryogenic temperature. This not only enables the preparation of superfluid helium under high cooling and high heat loads, but also allows for the recovery of cooling capacity in multiple temperature zones through gradient pressurization of the multi-stage cold press, resulting in a high degree of system integration. Furthermore, since no room temperature pump is required, the cooling capacity recovery rate is improved, and the maintenance costs of pump units are avoided, significantly enhancing the system's economy and operational reliability. However, the impeller of the centrifugal cold press in this method needs to operate within a stable operating range, exhibiting poor adaptability to changes in inlet heat load. When faced with high inlet heat load fluctuations, it is highly susceptible to shutdown failures. Moreover, the cold press is technically difficult and expensive to maintain; a failure can lead to the shutdown of the entire superfluid helium system, causing significant disruption.

[0008] Based on the above analysis, it can be seen that the existing mainstream superfluid helium cryogenic system pressurization modes all exhibit the characteristic of "single adaptation to specific scenarios". That is, each scheme can only exert its advantages within a specific heat load range, and cannot be flexibly switched according to the dynamic changes of heat load. It is difficult to be compatible with the application requirements of future major facilities such as cryogenic superconducting accelerators for "high heat load variation, high intensification, and industrial output". There is an urgent need for a new pressurization system design that can integrate the advantages of various schemes and adapt to multiple load scenarios. Utility Model Content

[0009] To address the problems of existing technologies that cannot dynamically switch and adapt to thermal load, this invention aims to provide a parallel multi-mode pressurized superfluid helium cryogenic system.

[0010] The parallel multi-mode pressurized superfluid helium cryogenic system of this invention includes a 4.5K cold box, a 2K cold energy acquisition module, a heat load module, and a room temperature compressor unit. The upstream of the 4.5K cold box is connected to the outlet of the room temperature compressor unit via a pipe, and the downstream of the 4.5K cold box is connected to the inlet of the 2K cold energy acquisition module via a pipe, used to cool the high-pressure room temperature helium gas output from the room temperature compressor unit to the 4.5K temperature range. The upstream of the 2K cold energy acquisition module is connected to the 4.5K cold box, and the downstream is divided into two paths: one path is connected to the heat load module via a pipe, used to transfer cold energy in the 2K temperature range; the other path returns to the room temperature compressor unit through at least three parallel cryogenic pressurization, mixed pressurization, and room temperature pressurization paths. The inlet is used to realize the helium reflux of the cryogenic system; wherein, the 2K cold energy acquisition module includes a 2K phase separator, a negative pressure heat exchanger, a JT valve, a three-stage cold press unit, a five-stage cold press unit, an electric heater, a room temperature pump unit, and a mechanical pump unit; the upstream of the heat load module is connected to the liquid phase outlet of the 2K phase separator through a pipeline, and the downstream is returned to the gas phase outlet pipeline of the 2K phase separator through a pipeline, which is used to simulate and verify the cold energy output of the superfluid helium cryogenic system or the cold energy demand of the user end; the inlet of the room temperature compressor unit is connected to the outlet of each pressurization path of the 2K cold energy acquisition module through multiple pipelines, which is used to compress room temperature and pressure helium into high pressure helium and deliver it to the 4.5K cold box.

[0011] In a preferred embodiment, the 4.5K cold box integrates a positive pressure heat exchanger stage and a negative pressure heat exchanger stage arranged in series. The positive pressure heat exchanger stage is located upstream of the 4.5K cold box, with its inlet connected to the outlet of the room temperature compressor unit, and is used to pre-cool the high-pressure room temperature helium using the downstream return cold helium. The negative pressure heat exchanger stage is located downstream of the 4.5K cold box, with its inlet connected to the outlet of the positive pressure heat exchanger stage and its outlet connected to the inlet of the 2K cold energy acquisition module, and is used to further cool the pre-cooled helium to a 4.5K subcooled state and recover the cold energy of the cold helium.

[0012] In a preferred embodiment, the inlet of the 2K phase separator is connected to the outlet of the negative pressure heat exchanger stage in the 4.5K cold box via a pipeline connecting the negative pressure heat exchanger and the JT valve in series. The negative pressure heat exchanger forms a heat exchange relationship with the gas phase outlet pipeline of the 2K phase separator, which is used to cool the 4.5K subcooled helium gas using the gas phase cold helium gas discharged from the 2K phase separator, thereby improving the liquid accumulation efficiency of the 2K phase separator. The JT valve is used to throttle and depressurize the subcooled helium gas after it has been cooled by the negative pressure heat exchanger, so as to realize the throttling and liquefaction of helium gas and its accumulation in the 2K phase separator. During the liquid accumulation process, flash gas is generated due to incomplete liquefaction, forming a gas-liquid two-phase system.

[0013] In a preferred embodiment, the five-stage cold press unit is composed of the first-stage cold press to the fifth-stage cold press connected in series, forming the core unit of the low-temperature pressurization mode; the inlet of the five-stage cold press unit is connected to the gas phase outlet of the negative pressure heat exchanger through a pipe equipped with a third low-temperature regulating valve, and the outlet is connected to the positive pressure heat exchanger stage inlet of the 4.5K cold box through a pipe equipped with a fourth low-temperature regulating valve, which is used to directly pressurize the gas phase cold helium to atmospheric pressure 1.05 bar, and control the temperature at 30K~40K.

[0014] In a preferred embodiment, the three-stage cold press unit consists of a first-stage cold press, a second-stage cold press, and a third-stage cold press connected in series, forming a low-temperature pressurization unit in a hybrid pressurization mode. The inlet of the three-stage cold press unit is connected to the gas phase outlet of the negative pressure heat exchanger through a pipe equipped with a first low-temperature regulating valve, which is used to increase the pressure of the gas phase cold helium discharged from the 2K phase separator from 31mbar to 200mbar~400mbar and control the temperature at 15K~20K. The outlet of the three-stage cold press unit is connected to a 4.5K cold box through a pipe equipped with a second low-temperature regulating valve, and flows sequentially through the negative pressure heat exchanger stage and the positive pressure heat exchanger stage of the 4.5K cold box to complete the cold energy recovery and heat up to room temperature before connecting to the mechanical pump unit, together forming a complete pressurization path in the hybrid pressurization mode.

[0015] In a preferred embodiment, the room temperature pump unit consists of a Roots pump unit and a backing mechanical pump unit, forming the core unit of the room temperature boosting mode; a first manual valve is provided between the connection port of the Roots pump unit and the backing mechanical pump unit; the inlet of the room temperature pump unit is connected to the outlet of the electric heater through a pipe, and the outlet is connected to the inlet of the room temperature compressor unit through a pipe equipped with a fourth manual valve; the inlet of the electric heater is connected to the gas phase outlet of the negative pressure heat exchanger through a pipe equipped with a fifth cryogenic regulating valve, for heating the cryogenic gas phase helium to a room temperature of about 280K.

[0016] In a preferred embodiment, the mechanical pump unit constitutes a normal temperature standby booster unit in a hybrid booster mode. Its inlet is connected to the outlet of the 4.5K cold box positive pressure heat exchanger stage via a pipeline, and its outlet is connected to the inlet of the room temperature compressor unit via a pipeline equipped with a third hand valve. The mechanical pump unit and the pre-stage mechanical pump unit of the room temperature pump unit are connected via a pipeline equipped with a second hand valve to form a parallel redundant structure, which can realize online replacement and maintenance.

[0017] In a preferred embodiment, a bypass pipeline is also included, which connects the gas phase outlet of the negative pressure heat exchanger to the positive pressure heat exchanger stage inlet of the 4.5K cold box. A sixth cryogenic regulating valve is provided on the bypass pipeline to control the bypass circulation of helium under no-load conditions.

[0018] In a preferred embodiment, the cryogenic components in the 2K cryogenic acquisition module, including a 2K phase separator, a negative pressure heat exchanger, JT valves, a three-stage cryogenic compressor unit, a five-stage cryogenic compressor unit, and related cryogenic regulating valves, are encapsulated within a 2K cold box. The ambient temperature components in the 2K cryogenic acquisition module, including an electric heater, a ambient temperature pump unit, a mechanical pump unit, and related ambient temperature regulating valves, are set independently of the 2K cold box. The 2K cold box, the 4.5K cold box, and the heat load module are connected through multi-channel cryogenic pipelines to transfer cryogenic energy from different temperature zones to corresponding functional areas. By integrating the core parallel cryogenic compressor unit into the same 2K cold box, not only is a highly compact layout of components achieved, reducing cryogenic pipeline loss and space occupation, but the system can also quickly respond to application scenarios with high heat load changes through precise switching of internal valves. This combination of integrated design and multi-mode switching function simplifies the system structure, reduces operation and maintenance costs, and ensures that the superfluid helium cryogenic system can operate efficiently under different load conditions, significantly improving the system's flexibility, economy, and reliability.

[0019] The parallel multi-mode pressurized superfluid helium cryogenic system of this invention integrates a 4.5K cold box, a 2K cold energy acquisition module, a heat load module, and a room temperature compressor unit. Utilizing the 2K cold energy acquisition module's ability to organically connect at least three parallel pressurization paths (cryogenic pressurization, hybrid pressurization, and room temperature pressurization) of the three mainstream superfluid helium cryogenic system pressurization methods, it can flexibly switch between appropriate pressurization methods to meet different heat load requirements. This not only avoids the need for excessive pump units in low-load scenarios but also ensures stable system operation and improves resistance to load fluctuations in high-load scenarios. Furthermore, it is adaptable to the high-temperature variable load, high-intensity, and industrialized power transmission requirements of future major facilities such as cryogenic superconducting accelerators. The system addresses application requirements and combines the high thermal load demands of users during the industrialization of superfluid helium to ensure it always operates within its optimal operating range. Simultaneously, the 4.5K cold box's initial cooling of high-pressure, ambient-temperature helium, the 2K cold energy acquisition module's transfer of cold energy from the 2K temperature zone, and the user-end liquid helium decompression process for generating superfluid helium work together to efficiently achieve stable acquisition and recycling of 2K superfluid helium. Furthermore, the multi-path reflux design ensures normal helium circulation, significantly improving and balancing the system's economy, flexibility, and reliability. This effectively solves the problems of existing superfluid helium cryogenic systems, such as limited compatibility of pressurization modes, high maintenance costs, insufficient continuous operation stability, and inability to dynamically match changes in thermal load. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a parallel multi-mode pressurized superfluid helium cryogenic system according to a preferred embodiment of the present invention. Detailed Implementation

[0021] The preferred embodiments of this utility model are given below with reference to the accompanying drawings and described in detail.

[0022] like Figure 1 As shown, a preferred embodiment of the parallel multi-mode pressurized superfluid helium cryogenic system according to this utility model includes a 4.5K cold box 100, a 2K cold energy acquisition module 200, a heat load module 300, and a room temperature compressor unit 400.

[0023] The 4.5K cold box 100 is the "preliminary cooling unit". Upstream, it is connected to the outlet of the room temperature compressor unit 400 (receiving high-pressure room temperature helium) through a pipeline, and downstream, it is connected to the inlet of the 2K cold capacity acquisition module 200 (delivering 4.5K subcooled helium) through a pipeline. It is responsible for cooling the high-pressure room temperature helium (pressure 15bar~18bar, temperature 280K) to the 4.5K temperature range.

[0024] Specifically, the 4.5K cold box 100 integrates a positive pressure heat exchanger stage 110 and a negative pressure heat exchanger stage 120 arranged in series. It should be understood that the 4.5K cold box 100 also integrates other cooling devices (such as turbine stages), which are existing technologies and will not be described in detail here.

[0025] The positive pressure heat exchanger stage 110 is located upstream of the 4.5K cold box 100. Its inlet is connected to the outlet of the room temperature compressor unit 400 (which receives high-pressure room temperature helium gas). It uses the downstream return cold helium gas (from the 2K cold energy acquisition module 200) to perform preliminary cooling of the high-pressure room temperature helium gas.

[0026] The negative pressure heat exchanger stage 120 is located downstream of the 4.5K cold box 100, with its inlet connected to the outlet of the positive pressure heat exchanger stage 110. It further cools the helium gas after initial cooling to a subcooled state of 4.5K, while recovering the cold helium gas cooling capacity from the 2K cold energy acquisition module 200.

[0027] The 2K cooling capacity acquisition module 200 is the "core pressurization and cryogenic unit," integrating all pressurization-related components. Its upstream is connected to the 4.5K cold box 100, and its downstream is divided into two paths: one path is connected to the heat load module 300 through a pipeline (used to transmit 2K temperature zone cooling capacity, which provides a cooling basis for the liquid helium at the user end, so that the liquid helium is throttled by the user-side pressure reducing device to generate 2K superfluid helium, thereby meeting the heat load's demand for 2K cooling capacity); the other path is returned to the inlet of the room temperature compressor unit 400 through different pressurization paths (to realize the helium return of the cryogenic system. During this return process, the helium undergoes state changes such as negative pressure and low temperature, and finally reaches room temperature and pressure before entering the room temperature compressor unit 400, that is, a temperature of 280K±10K and a pressure of 1.05bar±0.15bar).

[0028] Specifically, the 2K cold energy acquisition module 200 includes a 2K phase separator 210, a negative pressure heat exchanger 220, a Joule-Thomson valve (i.e., a JT valve) 201, a three-stage cold press unit 230, a five-stage cold press unit 240, an electric heater 250, a room temperature pump unit 260, and a mechanical pump unit 270. Among these, the 2K phase separator 210, negative pressure heat exchanger 220, JT valve 201, three-stage cold press unit 230, and five-stage cold press unit 240 are the low-temperature core components of the 2K cold energy acquisition module 200 (corresponding to...). Figure 1 The area defined by the dashed box in the diagram is encapsulated within the 2K cold box. The electric heater 250, room temperature pump unit 260, and mechanical pump unit 270 are the core ambient temperature components of the 2K cold energy acquisition module 200, and are set up independently of the 2K cold box. The 2K cold box, 4.5K cold box 100, and heat load module 300 are connected via multi-channel cryogenic pipelines to transfer cold energy from different temperature zones to their corresponding functional areas.

[0029] The 2K phase separator 210 is the "gas-liquid separation core" of the module. Its inlet is connected to the outlet of the negative pressure heat exchanger stage 120 in the 4.5K cold box 100 (which receives 4.5K subcooled helium) via a pipeline (with a negative pressure heat exchanger 220 and a JT valve 201 connected in series on the pipeline). The 4.5K subcooled helium from the 4.5K cold box 100 is cooled by the negative pressure heat exchanger 220. The JT valve 201 throttles and depressurizes the cooled subcooled helium, achieving helium liquefaction and liquid accumulation in the 2K phase separator 210. During the liquid accumulation process, flash gas is generated due to incomplete liquefaction, forming a two-phase gas-liquid system. The liquid phase (2K superfluid helium) accumulates in the liquid phase region and is transported to the heat load module 300 through the pipeline, while the gas phase enters the downstream pressurization circulation path. Meanwhile, the negative pressure heat exchanger 220 forms a heat exchange relationship with the gas phase outlet pipe of the 2K phase separator 210, thereby using the gas phase cold helium gas with a temperature close to 2K discharged from the 2K phase separator 210 to cool down the subcooled helium gas from the 4.5K cold box 100. By reducing the helium gas temperature, the liquefaction efficiency (i.e., liquid accumulation efficiency) in the 2K phase separator 210 after the JT valve 201 throttles is significantly improved.

[0030] The three-stage cold press unit 230 is a "hybrid pressurization mode cryogenic pressurization unit" consisting of a first-stage cold press 231, a second-stage cold press 232, and a third-stage cold press 233 connected in series. Its inlet is connected to the gas phase outlet of the negative pressure heat exchanger 220 through a pipeline (with a first cryogenic regulating valve 202 on the pipeline for controlling the helium flow and on / off). It performs preliminary pressurization on the gas phase cold helium discharged from the 2K phase separator 210, increasing the pressure from 31 mbar (i.e., 3.1 kPa) to 200 mbar~400 mbar, and controlling the temperature at 15K~20K, thus reducing the load for subsequent normal temperature pressurization. The outlet of the three-stage cold press unit 230 is connected to the inlet of the negative pressure heat exchanger stage 120 of the 4.5K cold box 100 through a pipeline (with a second cryogenic regulating valve 203 on the pipeline for controlling the helium flow and on / off). After passing through the negative pressure heat exchanger stage 120, the helium further flows through the positive pressure heat exchanger stage 110 to complete the cold energy recovery.

[0031] The five-stage cold press unit 240 is the "core unit of the low-temperature pressurization mode". It consists of the first-stage cold press 241 to the fifth-stage cold press 245 connected in series. The inlet is connected to the gas phase outlet of the negative pressure heat exchanger 220 through a pipeline (the pipeline is equipped with a third low-temperature regulating valve 205 for controlling the helium flow rate). The outlet is connected to the inlet of the positive pressure heat exchanger stage 110 of the 4.5K cold box 100 through a pipeline (the pipeline is equipped with a fourth low-temperature regulating valve 206 for controlling the helium flow rate). It directly pressurizes the gas phase cold helium in the entire low-temperature range without relying on the normal temperature pump set. The outlet pressure can directly reach the normal pressure of 1.05 bar, and the temperature is controlled at 30K~40K, which is suitable for stable operation under large loads.

[0032] The electric heater 250 is a "temperature zone conversion unit in ambient temperature pressurization mode". Its inlet is connected to the gas phase outlet of the negative pressure heat exchanger 220 through a pipe (the pipe is equipped with a fifth low temperature regulating valve 212 for controlling the on-off and flow of helium). Its outlet is connected to the inlet of the room temperature pump group 260 through a pipe, which heats the low temperature gas phase helium discharged from the negative pressure heat exchanger 220 to a room temperature of about 280K, which is compatible with the "ambient temperature inlet" requirement of the room temperature pump group 260.

[0033] The room temperature pump unit 260 is the "core unit of the normal temperature boosting mode". It consists of a Roots pump unit 261 and a backing mechanical pump unit 262. A first hand valve 207 is provided between the connection ports of the two pumps. The overall inlet is connected to the outlet of the electric heater 250 through a pipe. The overall outlet is connected to the inlet of the room temperature compressor unit 400 through a pipe (the pipe is equipped with a fourth hand valve 208) to boost the helium gas heated to room temperature. The function of the first hand valve 207 is to "isolate / connect" the Roots pump unit 261 and the backing mechanical pump unit 262, so that the two can work in combination (to meet high boosting requirements) or work independently (to adapt to different small loads).

[0034] Mechanical pump unit 270 is a "normal temperature standby booster unit in mixed booster mode". Its inlet is connected to the outlet of the positive pressure heat exchanger stage 110 of the 4.5K cold box 100 (i.e., the "normal temperature helium gas after cold recovery" pipeline in mixed mode) through a pipeline. Its outlet is connected to the inlet of the room temperature compressor unit 400 through a pipeline (with a third hand valve 211 on the pipeline). It forms a "parallel redundancy" with the front mechanical pump unit 262 of the room temperature pump unit 260 to jointly undertake the normal temperature booster task in mixed mode.

[0035] Additionally, the bypass line connects the gas phase outlet of the negative pressure heat exchanger 220 to the inlet of the positive pressure heat exchanger stage 110 of the 4.5K cold box 100. The sixth cryogenic regulating valve 204 is located on the bypass line, controlling the bypass circulation of helium when there is no load. The six cryogenic regulating valves 202 / 203 / 205 / 206 / 212 / 204 are all flow and on / off control components, adapted to cryogenic operating conditions.

[0036] Specifically, all four hand valves 207 / 209 / 211 / 208 are "rigid on / off control components," adapted for ambient temperature operation, and used for reliable isolation during module maintenance or mode switching. The first hand valve 207 isolates / connects the Roots pump unit 261 and the backing mechanical pump unit 262; the second hand valve 209 connects the "mixed-mode ambient temperature helium pipeline" to the inlet of the backing mechanical pump unit 262, controlling whether the backing mechanical pump unit 262 is in mixed mode; the third hand valve 211 controls the on / off connection from the outlet of the mechanical pump unit 270 to the inlet of the ambient temperature compressor unit 400; and the fourth hand valve 208 controls the on / off connection from the outlet of the ambient temperature pump unit 260 to the inlet of the ambient temperature compressor unit 400.

[0037] The heat load module 300 is a "cooling demand simulation unit". Its inlet is connected to the liquid phase outlet of the 2K phase separator 210 in the 2K cooling acquisition module 200 (to receive the cooling capacity of the 2K temperature zone) through a pipeline. The outlet flows back to the gas phase outlet pipeline of the 2K phase separator 210 through a pipeline (to send the heated and vaporized gaseous helium back to the pressurization cycle). The built-in heating element simulates the actual cooling demand of the user end (such as the heat load of the low temperature superconducting accelerator) or verifies the cooling output capacity of the system. After ensuring that the cooling capacity of the 2K superfluid helium is effectively utilized, the gaseous helium can flow back to the pressurization cycle to avoid the waste of cooling capacity.

[0038] The room temperature compressor unit 400 is a "power circulation unit," which is a combination of one or more screw compressors. Its inlet is connected to the outlets of the various pressurization paths of the 2K cold capacity acquisition module 200 through different pipes (the outlet of the five-stage cold compressor unit 240 after heat exchange in the 4.5K cold box 100, the outlet of the room temperature pump unit 260 after the fourth hand valve 208, and the outlet of the mechanical pump unit 270 after the third hand valve 211). The outlet is connected to the inlet of the positive pressure heat exchanger stage 110 of the 4.5K cold box 100, which compresses the ambient temperature and pressure helium gas returning from each pressurization path to a high pressure of about 15 bar, providing power for the helium gas circulation of the entire system, while meeting the cooling pressure requirements of the 4.5K cold box 100.

[0039] The core improvement of this utility model is "multi-mode switching to adapt to different loads". The three modes achieve precise control through valve on / off and component start / stop. The specific descriptions are as follows, combined with small / medium / large load scenarios.

[0040] First, when the heat load module 300 is below 200W and requires multiple operating condition changes, the system should be switched to the ambient temperature boosting mode first. The electric heater 250, the Roots pump set 261 + the forepump mechanical pump set 262 (operating in combination), and the ambient temperature compressor set 400 are started. The gas phase flows into the electric heater 250 and is heated to ambient temperature. Then, it is boosted by the operating ambient temperature pump set 260. After the gas phase is maintained at ambient temperature and pressure, it is connected to the ambient temperature compressor set 400 to complete the boosting cycle. In this mode, the three-stage cold compressor set 230, the five-stage cold compressor set 240, and the mechanical pump set 270 are shut down. The gas phase of the 2K phase separator 210 is connected to the fifth cryogenic regulating valve 212, then to the electric heater 250 (heating to 280K), followed by the Roots pump set 261 + the backing mechanical pump set 262 (pressurizing to 1.05 bar), then to the fourth hand valve 208, the ambient temperature compressor set 400 (compressing to 15 bar), and the 4.5K cold box 100 (cooling to 4.5K), forming a cycle. Specifically, the first hand valve 207 enables independent / combined operation of the Roots pump set 261 and the backing mechanical pump set 262. Under low loads, only the backing mechanical pump set 262 needs to be operated (no need for full activation), solving the problem of existing technologies requiring multiple pump sets to be fully activated for low loads. This allows the ambient temperature pump set 260 to be adapted to low loads, reducing energy consumption and maintenance through modular control.

[0041] Second, when the heat load module 300 operates at 200W~500W, it should be switched to the hybrid booster mode first. The three-stage cold compressor unit 230, mechanical pump unit 270, and room temperature compressor unit 400 should be started. The five-stage cold compressor unit 240, electric heater 250, and Roots pump unit 261 should be shut down. The flow is as follows: 2K phase separator 210 (gas phase) → first cryogenic regulating valve 202 → three-stage cold compressor unit 230 (pressurized to 200~400mbar, 15~20K) → second cryogenic regulating valve 203 → 4.5K cold box 100 (negative pressure heat exchanger stage 120 → positive pressure heat exchanger stage 110, recovering cold energy to 280K) → mechanical pump unit 270 (pressurized to 1.05bar) → third hand valve 211 → room temperature compressor unit 400 → 4.5K cold box 100, forming a cycle. Specifically, when the mechanical pump unit 270 needs maintenance, closing the third hand valve 211 and opening the second hand valve 209 can start the upstream mechanical pump unit 262 to replace it, realizing "online maintenance without stopping the machine" and solving the problem of "maintenance must be stopped" in the existing technology. Thus, by combining the low-temperature cold compressor and the room temperature pump unit, cold energy recovery and redundant maintenance can be achieved. Conversely, when the pre-stage mechanical pump unit 262 is shut down for maintenance, the mechanical pump unit 270 can be put back into operation, i.e., the second hand valve 209 is closed and the third hand valve 211 is opened. 2K phase separator 210 gas phase → first low temperature regulating valve 202 → three-stage cold compressor unit 230 (pressurized to 200~400mbar, 15~20K) → second low temperature regulating valve 203 → 4.5K cold box 100 (negative pressure heat exchanger stage 120 → positive pressure heat exchanger stage 110, recovering cold energy to 280K) → second hand valve 209 → pre-stage mechanical pump unit 262 (pressurized to 1.05bar) → fourth hand valve 208 → room temperature compressor unit 400 → 4.5K cold box 100, forming a cycle.

[0042] Third, when the heat load module 300 operates at 500W~4000W, for example, when it needs to reach kilowatt level or above and the operating condition requires long-term stable operation, it should be switched to the low-temperature boosting mode first. The five-stage cold press unit 240 and the room temperature compressor unit 400 are started. The three-stage cold press unit 230, electric heater 250, room temperature pump unit 260 and mechanical pump unit 270 are shut down. 2K phase separator 210 gas phase → third low temperature regulating valve 205 → five-stage cold press unit 240 (pressurized to 1.05 bar, 30~40K) → fourth low temperature regulating valve 206 → 4.5K cold box 100 positive pressure heat exchanger stage 110 (recovering cold energy to 280K) → room temperature compressor unit 400 → 4.5K cold box 100, forming a cycle. In particular, the five-stage cold press unit 240 directly achieves low-temperature full pressurization without relying on room temperature pump units. This avoids the energy consumption and maintenance problems of existing technologies that require multiple pump units in series for large loads, and is suitable for scenarios with large loads and stable operating conditions (avoiding the problem of poor adaptability of low-temperature pressurization mode to heat load fluctuations). At the same time, it is integrated into the 2K cold box, reducing the risk of pipeline leakage, thus achieving full low-temperature pressurization without room temperature pump unit losses, and is suitable for high-efficiency operation under large loads.

[0043] The three gas-phase pressurization paths described above are configured in parallel, and the pressurization paths can be switched in a matching manner by adjusting the valves according to changes in the heat load module 300. A bypass loop for no-load operation is provided between the three parallel gas-phase pressurization paths. When the heat load module 300 has no cooling demand, the system switches to the "bypass loop," and the bypass loop of helium under no-load conditions is achieved through the on / off control of the sixth cryogenic regulating valve 204. The flow is: 2K phase separator 210 gas phase → negative pressure heat exchanger 220 → sixth cryogenic regulating valve 204 → 4.5K cold box 100 positive pressure heat exchanger stage 110 (cooling capacity is recovered while temperature rises to room temperature) → room temperature compressor unit 400 → 4.5K cold box 100, forming a no-load loop to avoid component idling losses and to adapt to the operating condition where the heat load module has no cooling demand, while also coordinating with the control function of the bypass pipeline.

[0044] Thus, the parallel multi-mode pressurized superfluid helium cryogenic system of this utility model organically connects the three mainstream superfluid helium cryogenic system pressurization modes in parallel. Through core improvements such as "component integration (integrating core components such as the three-stage cold press unit, the five-stage cold press unit, the negative pressure heat exchanger, and the 2K phase separator into a 2K cold box package), mode modularization (achieving precise switching with the help of several cryogenic regulating valves and manual valves), and maintenance redundancy (adopting a parallel replacement design for pump groups, especially in the hybrid pressurization mode, allowing for the interchangeable connection or disconnection of the upstream mechanical pump group 262)," the system specifically addresses the problems of "requiring a large number of pump groups for small loads, requiring equipment maintenance shutdowns, and low operating efficiency under large loads" in existing technologies. At the same time, the system can flexibly switch operating modes according to the high thermal load requirements of users during the industrialization of superfluid helium, which not only extends the online stable operation time of commonly used hybrid pressurization modes, but also ensures that the superfluid helium cryogenic system always operates in the optimal working range, ultimately significantly improving the system's flexibility, economy, and reliability.

[0045] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of this utility model. Various variations can be made to the above embodiments of this utility model. That is, all simple and equivalent changes and modifications made based on the claims and description of this utility model fall within the protection scope of the claims of this utility model. Any aspects not described in detail in this utility model are conventional technical content.

Claims

1. A parallel multi-mode pressurized superfluid helium cryogenic system, characterized in that, It includes a 4.5K cold box (100), a 2K cold capacity acquisition module (200), a heat load module (300), and a room temperature compressor unit (400). The upstream of the 4.5K cold box (100) is connected to the outlet of the room temperature compressor unit (400) via a pipe, and the downstream is connected to the inlet of the 2K cold energy acquisition module (200) via a pipe, which is used to cool the high-pressure room temperature helium gas output by the room temperature compressor unit (400) to the 4.5K temperature range. The upstream of the 2K cold energy acquisition module (200) is connected to the 4.5K cold box (100), and the downstream is divided into two paths: one path is connected to the heat load module (300) through a pipeline for transmitting the cold energy of the 2K temperature zone; the other path flows back to the inlet of the room temperature compressor unit (400) through at least three parallel low temperature pressurization, mixed pressurization and normal temperature pressurization paths for realizing the helium reflux of the low temperature system; wherein, the 2K cold energy acquisition module (200) includes a 2K phase separator (210), a negative pressure heat exchanger (220), a JT valve (201), a three-stage cold press unit (230), a five-stage cold press unit (240), an electric heater (250), a room temperature pump unit (260) and a mechanical pump unit (270). The upstream of the heat load module (300) is connected to the liquid phase outlet of the 2K phase separator (210) via a pipe, and the downstream is returned to the gas phase outlet pipe of the 2K phase separator (210) via a pipe, which is used to simulate and verify the cooling output of the superfluid helium cryogenic system or the cooling demand of the user end. The inlet of the room temperature compressor unit (400) is connected to the outlet of each pressurization path of the 2K cold energy acquisition module (200) through multiple pipelines, which is used to compress room temperature and pressure helium into high pressure helium and deliver it to the 4.5K cold box (100).

2. The parallel multi-mode pressurized superfluid helium cryogenic system according to claim 1, characterized in that, The 4.5K cold box (100) integrates a positive pressure heat exchanger stage (110) and a negative pressure heat exchanger stage (120) arranged in series. The positive pressure heat exchanger stage (110) is located upstream of the 4.5K cold box (100), and its inlet is connected to the outlet of the room temperature compressor unit (400). It is used to use the downstream return cold helium to initially cool the high-pressure room temperature helium. The negative pressure heat exchanger stage (120) is located downstream of the 4.5K cold box (100), and its inlet is connected to the outlet of the positive pressure heat exchanger stage (110). Its outlet is connected to the inlet of the 2K cold energy acquisition module (200). It is used to further cool the helium after initial cooling to a 4.5K supercooled state and recover the cold energy of the cold helium.

3. The parallel multi-mode pressurized superfluid helium cryogenic system according to claim 2, characterized in that, The inlet of the 2K phase separator (210) is connected to the outlet of the negative pressure heat exchanger stage (120) in the 4.5K cold box (100) via a pipeline connected in series with the negative pressure heat exchanger (220) and the JT valve (201). The negative pressure heat exchanger (220) and the gas phase outlet pipeline of the 2K phase separator (210) form a heat exchange relationship, which is used to cool the 4.5K subcooled helium gas with the gas phase cold helium gas discharged from the 2K phase separator (210) to improve the liquid accumulation efficiency of the 2K phase separator (210). The JT valve (201) is used to throttle and depressurize the subcooled helium gas after it has been cooled by the negative pressure heat exchanger (220), so as to realize the throttling and liquefaction of helium gas and the accumulation of liquid in the 2K phase separator (210). During the liquid accumulation process, flash gas is generated due to incomplete liquefaction, forming a gas-liquid two-phase system.

4. The parallel multi-mode pressurized superfluid helium cryogenic system according to claim 2, characterized in that, The five-stage cold press unit (240) is composed of the first-stage cold press (241) to the fifth-stage cold press (245) connected in series, forming the core unit of the low-temperature pressurization mode. The inlet of the five-stage cold press unit (240) is connected to the gas phase outlet of the negative pressure heat exchanger (220) through a pipe equipped with a third low-temperature regulating valve (205), and the outlet is connected to the inlet of the positive pressure heat exchanger stage (110) of the 4.5K cold box (100) through a pipe equipped with a fourth low-temperature regulating valve (206), which is used to directly pressurize the gas phase cold helium to atmospheric pressure 1.05 bar and control the temperature at 30K~40K.

5. The parallel multi-mode pressurized superfluid helium cryogenic system according to claim 2, characterized in that, The three-stage cold press unit (230) is composed of a first-stage cold press (231), a second-stage cold press (232), and a third-stage cold press (233) connected in series, forming a low-temperature boosting unit in a mixed boosting mode. The inlet of the three-stage cold press unit (230) is connected to the gas phase outlet of the negative pressure heat exchanger (220) through a pipe equipped with a first low-temperature regulating valve (202), which is used to increase the pressure of the gas phase cold helium discharged from the 2K phase separator (210) from 31 mbar to 200 mbar. mbar~400mbar, temperature controlled at 15K~20K; the outlet of the three-stage cold press unit (230) is connected to the 4.5K cold box (100) through a pipe equipped with a second low temperature regulating valve (203), and flows through the negative pressure heat exchanger stage (120) and positive pressure heat exchanger stage (110) of the 4.5K cold box (100) in sequence to complete the cold energy recovery and heat up to room temperature, and then connects to the mechanical pump group (270) to form a complete pressurization path of the mixed pressurization mode.

6. The parallel multi-mode pressurized superfluid helium cryogenic system according to claim 2, characterized in that, The room temperature pump unit (260) consists of a Roots pump unit (261) and a backing mechanical pump unit (262), forming the core unit of the room temperature boosting mode. A first hand valve (207) is provided between the connection ports of the Roots pump unit (261) and the backing mechanical pump unit (262). The inlet of the room temperature pump unit (260) is connected to the outlet of the electric heater (250) through a pipe, and the outlet is connected to the inlet of the room temperature compressor unit (400) through a pipe with a fourth hand valve (208). The inlet of the electric heater (250) is connected to the gas phase outlet of the negative pressure heat exchanger (220) through a pipe with a fifth low temperature regulating valve (212), which is used to heat the low temperature gas phase helium to a room temperature of about 280K.

7. The parallel multi-mode pressurized superfluid helium cryogenic system according to claim 6, characterized in that, The mechanical pump unit (270) constitutes a normal temperature standby booster unit in a mixed booster mode. Its inlet is connected to the outlet of the positive pressure heat exchanger stage (110) of the 4.5K cold box (100) through a pipe, and its outlet is connected to the inlet of the room temperature compressor unit (400) through a pipe equipped with a third hand valve (211). The mechanical pump unit (270) and the pre-stage mechanical pump unit (262) of the room temperature pump unit (260) are connected through a pipe equipped with a second hand valve (209) to form a parallel redundant structure, which can realize online replacement and maintenance.

8. The parallel multi-mode pressurized superfluid helium cryogenic system according to claim 2, characterized in that, It also includes a bypass pipeline, which connects the gas phase outlet of the negative pressure heat exchanger (220) to the inlet of the positive pressure heat exchanger stage (110) of the 4.5K cold box (100). The bypass pipeline is equipped with a sixth cryogenic regulating valve (204) for controlling the bypass circulation of helium under no-load conditions.

9. The parallel multi-mode pressurized superfluid helium cryogenic system according to claim 1, characterized in that, The low-temperature components in the 2K cold energy acquisition module (200) include a 2K phase separator (210), a negative pressure heat exchanger (220), a JT valve (201), a three-stage cold press unit (230), a five-stage cold press unit (240), and related low-temperature regulating valves, all encapsulated within the 2K cold box. The ambient temperature components in the 2K cold energy acquisition module (200) include an electric heater (250), an ambient temperature pump unit (260), a mechanical pump unit (270), and related ambient temperature regulating valves, all set independently of the 2K cold box. The 2K cold box, the 4.5K cold box (100), and the heat load module (300) are connected by multi-channel low-temperature pipelines to transmit cold energy from different temperature zones to the corresponding functional areas.

Images