CN102087065B - Liquid helium external process equipment for high pumping speed cryogenic system - Google Patents

Abstract

The invention discloses a liquid helium external flow path system design for a high pumping speed deep cooling system, which comprises a liquid helium supply system, a liquid nitrogen supply system, a gaseous nitrogen supply system, a gaseous helium supply system, a heat sink system and a fluid discharging system. The system provides liquid helium cooling by adopting an open-type method, and has the advantages of being low in cost, adopting simple equipment, being convenient for usage and being convenient for transportation owing to the adoption of a 500L liquid helium tank for liquid helium supply; the system is safe in operation as provided with a safety valve; precooling is performed at first by utilizing liquid nitrogen before the liquid helium supply system is started, thereby avoiding the waste of expensive liquid helium; after the liquid nitrogen supply system completes the precooling, the residual liquid nitrogen in the heat sink system is purged by the gaseous nitrogen supply system, then the residual gaseous nitrogen in the heat sink system is purged by the gaseous helium supply system, and finally the liquid helium supply system is started, thereby preventing the residual liquid nitrogen in the heat sink system being frozen by the liquid helium to block off the pipeline; and the switching between the liquid helium supply system and the liquid nitrogen supply system is implemented by using a quick coupling in order to avoid cold leakage; the method has extensive applicable scope and useful value.

Description

Liquid helium external process equipment for high pumping speed cryogenic system

【Technical field】

The invention relates to the design of a low temperature external process system necessary for simulating a vacuum cryogenic environment. The invention is especially used for simulating the design of the liquid helium external process system necessary for the ultra-high vacuum cryogenic environment with high pumping speed.

【Background technique】

In order to ensure that various spacecraft can be successfully launched, run reliably, complete various scheduled tasks and return to the ground smoothly, it is necessary to establish ground thermal vacuum environment simulation experimental equipment, and the cryogenic liquid external process delivery system is ground vacuum An important part of environmental simulation experiment equipment.

At present, most domestic and foreign thermal vacuum environment simulation experimental equipment adopt liquid nitrogen external process for refrigeration to simulate the cold and dark environment of space, but for systems that require large air release volume and high pumping speed, the degree of vacuum that can be simulated is not high , can only simulate the environmental pressure below 100km. With the rapid development of China's aerospace industry, the need for large-scale manned spaceflight and the demand for rocket engine plume experiments, the use of liquid nitrogen external process for refrigeration has been unable to meet the requirements, which requires the use of liquid helium external process for refrigeration. It can simulate the environmental pressure of more than 100km, which is closer to the real vacuum and cryogenic environment. The liquid helium system can make the static vacuum inside the vacuum container reach 10 ^-6 ~ 10 ^-7 Pa, which is 1 to 2 orders of magnitude higher than the static vacuum that can be achieved by the existing liquid nitrogen system.

For a high-pumping-speed cryogenic system with a large outgassing volume, the amount of liquid helium is very large. For example, the large-scale plume experimental system developed by Beihang University has a liquid helium heat sink area of 200m ² . The helium heat sink is divided into 4 sections along the axial direction of the cabin, and the amount of liquid helium consumed for each experiment is 5-6m ³ , and the experiment time is 5-6 hours. According to market research, liquid helium resources are scarce and need to be imported from the United States. After importing, they are divided into 500L liquid helium tanks. There are a large number of 500L liquid helium tanks in China, and the transportation is also convenient, and the rental cost of liquid helium tanks is not high. Save money by not buying liquid helium tanks yourself. According to the market research results and considering the convenience of transportation, the liquid helium external process system is designed for the 500L liquid helium tank.

【Content of invention】

The purpose of the present invention is to provide a simple, reliable and practical liquid helium external process system design for simulating ultra-high vacuum cryogenic environment. The problem to be solved by the invention is that the equipment is simple; the cost is low; liquid helium is saved; the operation is simple; and the reliability is high. For this reason, the system adopts an open method to provide liquid helium refrigeration, and part of the delivery pipelines are shared; in order to save liquid helium, the supply flow of liquid helium can be adjusted, and liquid nitrogen, gas nitrogen and gas helium are used to cooperate with liquid nitrogen during the pre-cooling process of the heat sink. Helium co-precooling.

The design of the liquid helium external process system for the high pumping speed cryogenic system shown in Figure 1 adopts an open system, mainly including liquid helium supply system, liquid nitrogen supply system, gas nitrogen supply system, gas helium supply system, heat sink system and fluid discharge systems.

The liquid helium supply system includes a 500L liquid helium tank (1), pipeline safety valve (2), cryogenic liquid helium hand valve (3), quick slot (14) and liquid helium Dewar pipeline.

The liquid nitrogen supply system includes a liquid nitrogen storage tank (6), a pipeline safety valve (5, 13), a low-temperature liquid nitrogen hand valve (4), a quick slot (15) and a liquid nitrogen Dewar pipeline.

The gas nitrogen supply system includes a gas nitrogen tank (9), a pipeline safety valve (8), a cryogenic liquid nitrogen hand valve (7) and a liquid nitrogen Dewar pipeline.

The gas helium supply system includes a gas helium tank (12), a pipeline safety valve (11), a cryogenic liquid nitrogen hand valve (10) and a liquid nitrogen Dewar pipeline.

The heat sink system includes a quick plug (17), a corrugated hose (18), and a heat sink (19).

The fluid discharge system includes a pipeline safety valve (20), a cryogenic thermometer (21), a cryogenic liquid helium hand valve (22) and a liquid helium Dewar pipeline.

It can be seen from Figure 1 that the system is an open system. Liquid nitrogen, gas nitrogen, gas helium and liquid helium are all discharged to the atmosphere through the fluid discharge system after passing through the heat sink system. When the heat sink system is pre-cooled, the fast Insert the plug (17) into the quick slot (15) to complete the supply of liquid nitrogen, gas nitrogen and gas helium successively, then pull out the quick plug (17) from the quick slot (15) and insert it into the quick slot (14 ), the liquid helium supply is finally completed. The effect of the corrugated hose (18) is to facilitate the quick extraction and insertion of the quick plug (17). The function of pipeline safety valves (2, 5, 8, 11, 13, 20) is to prevent excessive pressure in the system pipeline and ensure pressure safety. The function of the cryogenic thermometer (21) is to monitor the fluid temperature at the outlet of the heat sink system, and to control the supply of liquid nitrogen and liquid helium through the temperature value during the pre-cooling process, so as to reduce the consumption of liquid nitrogen and liquid helium. In order to avoid low-temperature cold leakage, the pipes and valves in the liquid helium supply system, heat sink system and fluid discharge system are all made of 316 stainless steel; the pipes and valves in the liquid nitrogen supply system, gas nitrogen supply system, and gas helium supply system The materials are all made of 304 stainless steel.

The connection mode of the quick connector shown in Fig. 2 is a socket structure, which consists of a quick plug (17) and a quick slot (14 or 15). Among them, the quick plug (17) includes the vacuum tile pipeline (23), the plug flange (24), the sealing ring (25); the quick slot (14 or 15) includes the vacuum tile pipeline (28), the damping sleeve (27), socket flange (26). The quick connector can be quickly plugged in and out to prevent the valves and pipelines of the liquid nitrogen supply system from being damaged by the liquid helium. The damping sleeve (27) consists of 6 continuous sealing rings, which are used to prevent liquid leakage and reduce heat leakage.

The advantages and positive effects of the simple liquid helium external process system supply method for cryogenic systems of the present invention are: (1) The open method is adopted to provide liquid helium refrigeration, which is low in cost, simple in equipment and easy to use; ( 2) The 500L liquid helium tank is used for liquid supply, which is convenient for transportation and low rental price; (3) The system pipeline is equipped with a safety valve to ensure the safety of the system operation; (4) Before the liquid helium supply system starts, use cheap liquid nitrogen Pre-cooling avoids the waste of expensive liquid helium; (5) After the pre-cooling of the liquid nitrogen supply system is completed, first use the gas nitrogen supply system to blow off the residual liquid nitrogen in the heat sink system, and then use the gas helium supply system to blow off the heat sink The remaining gas nitrogen in the system, and finally start the liquid helium supply system, to avoid the residual liquid nitrogen in the heat sink system being frozen by the liquid helium to block the pipeline; (6) Use quick connectors to switch between the liquid nitrogen supply system and the liquid helium supply system , so that liquid nitrogen and liquid helium are physically isolated, avoiding the occurrence of liquid helium cold leakage during the switching process; (7) Liquid nitrogen, gas nitrogen, gas helium and liquid helium supply systems share the fluid discharge system to save costs; (8) ) The flow rate of liquid nitrogen, gas nitrogen, gas helium and liquid helium supply system can be adjusted manually; (9) A cryogenic thermometer is installed at the outlet of the heat sink system to monitor the fluid temperature at the outlet of the heat sink; (10) This method It has a wide range of applications and use value.

【Description of drawings】

Figure 1 is a schematic diagram of the open liquid helium external flow system

Figure 2 is a quick connector (quick plug and quick slot)

【Specific implementation method】

The present invention will be further described below with reference to the accompanying drawings.

The devices used to implement the liquid helium external process system supply method mainly include a liquid helium supply system, a liquid nitrogen supply system, a gas nitrogen supply system, a gas helium supply system, a heat sink system and a fluid discharge system. The liquid helium supply system includes a 500L liquid helium tank (1), pipeline safety valve (2), cryogenic liquid helium hand valve (3), quick slot (14) and liquid helium Dewar pipeline. The liquid nitrogen supply system includes a liquid nitrogen storage tank (6), a pipeline safety valve (5, 13), a low-temperature liquid nitrogen hand valve (4), a quick slot (15) and a liquid nitrogen Dewar pipeline. The gas nitrogen supply system includes a gas nitrogen tank (9), a pipeline safety valve (8), a cryogenic liquid nitrogen hand valve (7) and a liquid nitrogen Dewar pipeline. The gas helium supply system includes a gas helium tank (12), a pipeline safety valve (11), a cryogenic liquid nitrogen hand valve (10) and a liquid nitrogen Dewar pipeline. The heat sink system includes a quick plug (17), a corrugated hose (18), and a heat sink (19). The fluid discharge system includes a pipeline safety valve (20), a cryogenic thermometer (21), a cryogenic liquid helium hand valve (22) and a liquid helium Dewar pipeline.

It can be seen from Figure 1 that the system is an open system. Liquid nitrogen, gas nitrogen, gas helium and liquid helium are all discharged to the atmosphere through the fluid discharge system after passing through the heat sink system. When the heat sink system is pre-cooled, the fast Insert the plug (17) into the quick slot (15) to complete the supply of liquid nitrogen, gas nitrogen and gas helium successively, then pull out the quick plug (17) from the quick slot (15) and insert it into the quick slot (14 ), the liquid helium supply is finally completed. The effect of the corrugated hose (18) is to facilitate the quick extraction and insertion of the quick plug (17). The function of pipeline safety valves (2, 5, 8, 11, 13, 20) is to prevent excessive pressure in the system pipeline and to release air. The function of the cryogenic thermometer (21) is to monitor the fluid temperature at the outlet of the heat sink system, and to control the supply of liquid nitrogen and liquid helium through the temperature value during the pre-cooling process, so as to reduce the consumption of liquid nitrogen and liquid helium. In order to avoid low-temperature cold leakage, the pipes and valves in the liquid helium supply system, heat sink system and fluid discharge system are all made of 316 stainless steel. The pipes and valves in the liquid nitrogen supply system, gas nitrogen supply system, and gas helium supply system The materials are all made of 304 stainless steel.

Liquid helium is expensive. In order to reduce the consumption of liquid helium and reduce the cost of experiment operation, first use cheap liquid nitrogen to pre-cool the heat sink system. After the liquid nitrogen supply system pre-cools the heat sink system to a certain temperature, start the gas nitrogen supply system to blow. Remove the residual liquid nitrogen in the heat sink system, then start the gas helium supply system to blow off the residual gas nitrogen in the heat sink system, and finally start the liquid helium supply system to continue to pre-cool the heat sink system. The specific process of pre-cooling the heat sink system is as follows:

(1) Before starting the system, check whether the system pipelines and valves are in normal condition;

(2) Insert the quick plug (17) into the quick slot (15) to start the liquid nitrogen supply system: open the cryogenic liquid nitrogen hand valve (4) to deliver liquid nitrogen to the heat sink system for pre-cooling, and at the same time open the cryogenic liquid helium hand valve Valve (22), liquid nitrogen becomes a two-phase fluid with more gas and less liquid after passing through the heat sink system, and is discharged to the outside through the fluid discharge system. When the heat sink system is pre-cooled to the liquid nitrogen temperature zone, close the low-temperature liquid nitrogen hand valve (4);

(3) Start the gas nitrogen supply system: open the low-temperature liquid nitrogen hand valve (7) to deliver gas nitrogen to the heat sink system to blow off the residual liquid nitrogen in the heat sink system. When the liquid nitrogen in the heat sink system is blown off Finally, close the cryogenic liquid nitrogen hand valve (7);

(4) Start the gas and helium supply system: open the low-temperature liquid nitrogen hand valve (10) to deliver gas and helium to the heat sink system to blow off the residual gas and nitrogen in the heat sink system. When the gas and nitrogen in the heat sink system are blown off Finally, close the cryogenic liquid nitrogen hand valve (10);

(5) Pull out the quick slot head (17) from the quick slot (15), insert it into the quick slot (14), and check whether the connection is intact;

(6) Start the liquid helium supply system: open the low-temperature liquid helium hand valve (3) to deliver liquid helium to the heat sink system to continue precooling the heat sink system. When the heat sink system is precooled to the liquid helium temperature zone, That is to complete the pre-cooling work of the heat sink system.

Claims (8)

1. The liquid helium external process equipment used in the high pumping speed cryogenic system mainly includes a liquid helium supply system, a liquid nitrogen supply system, a gas nitrogen supply system, a gas helium supply system, a heat sink system and a fluid discharge system, and is characterized in that : It adopts an open system, and the supply volume of liquid or gas can be adjusted; liquid nitrogen, gas nitrogen, gas helium and liquid helium are all discharged to the atmosphere directly through the fluid discharge system after passing through the heat sink system; the system is equipped with quick connectors, which can realize The rapid switching of liquid nitrogen and liquid helium supply systems prevents liquid helium from freezing the pipelines and valves of the liquid nitrogen supply system; the system is equipped with a pipeline safety valve to prevent excessive system pressure; the system is equipped with a cryogenic thermometer for monitoring Fluid temperature at the outlet of the sink system; The connection mode of the quick joint is a socket structure, which is composed of a quick plug (17) and a quick slot (14 or 15); wherein, the quick plug (17) includes a vacuum tile pipeline (23), a plug flange (24) and sealing ring (25); quick slot (14 or 15) includes vacuum tile pipeline (28), damping sleeve (27) and slot flange (26); there are two quick slots, the first One quick slot (14) is connected to the liquid helium supply system, and the second quick slot (15) is connected to the liquid nitrogen supply system, the gas nitrogen supply system and the gas helium supply system. Insert it into the second quick slot (15), and then perform the process in sequence: open the liquid nitrogen supply system, deliver liquid nitrogen to the heat sink system for pre-cooling, and open the low-temperature liquid helium hand valve (22) at the same time, after the liquid nitrogen passes through the heat sink system It becomes a two-phase fluid with more gas and less liquid, and it is discharged to the outside through the fluid discharge system. When the heat sink system is pre-cooled to the liquid nitrogen temperature zone, the liquid nitrogen supply system is closed; the gas nitrogen supply system is opened to deliver to the heat sink system. Gas nitrogen, when the liquid nitrogen in the heat sink system is blown off, close the gas nitrogen supply system; start the gas helium supply system, deliver gas helium to the heat sink system, when the gas nitrogen in the heat sink system is blown off, turn off the gas helium supply system; pull out the quick plug (17) from the second quick slot (15), insert it into the first quick slot (14), start the liquid helium supply system, and deliver liquid helium to the heat sink system for Continue to pre-cool the heat sink system. When the heat sink system is pre-cooled to the liquid helium temperature zone, complete the pre-cooling work of the heat sink system. 2. The liquid helium external process equipment for high pumping speed cryogenic system according to claim 1, characterized in that: the liquid helium supply system includes a 500L liquid helium tank (1), a pipeline safety valve (2), a cryogenic The liquid helium hand valve (3), the first quick slot (14) and the liquid helium Dewar pipeline provide liquid helium refrigeration for the heat sink system; a 500L liquid helium tank is used for liquid supply; the pipeline safety valve is used to prevent system pressure Too high; 316 stainless steel is used for system piping and valve materials. 3. The liquid helium external process equipment for high pumping speed cryogenic system according to claim 1, characterized in that: the liquid nitrogen supply system includes a liquid nitrogen storage tank (6), pipeline safety valves (5, 13) , low-temperature liquid nitrogen hand valve (4), second quick slot (15) and liquid nitrogen Dewar pipeline to provide liquid nitrogen refrigeration for the heat sink system; the pipeline safety valve is used to prevent the system pressure from being too high; the system pipeline , The valve material is made of 304 stainless steel. 4. The liquid helium external process equipment for high pumping speed cryogenic system according to claim 1, characterized in that: the gas nitrogen supply system includes a gas nitrogen tank (9), a pipeline safety valve (8), a cryogenic gas Nitrogen hand valve (7) and gas nitrogen Dewar pipeline provide gas nitrogen blowing for the heat sink system; pipeline safety valve is used to prevent system pressure from being too high; system pipelines and valves are made of 304 stainless steel. 5. The liquid helium external process equipment for high pumping speed cryogenic system according to claim 1, characterized in that: the gas helium supply system includes a gas helium tank (12), a pipeline safety valve (11), a cryogenic gas The helium hand valve (10) and the gas-helium Dewar pipeline provide helium blow-off for the heat sink system; the pipeline safety valve is used to prevent the system pressure from being too high; the material of the system pipeline and valves is 304 stainless steel. 6. The liquid helium external process equipment for high pumping speed cryogenic system according to claim 1, characterized in that: the heat sink system includes quick plug (17), corrugated hose (18), heat sink (19) The effect of the corrugated hose (18) is to facilitate the quick plug-in of the quick plug (17); the material of the system piping is selected from 316 stainless steel. 7. The liquid helium external process equipment for high pumping speed cryogenic system according to claim 1, characterized in that: the fluid discharge system includes a pipeline safety valve (20), a cryogenic thermometer (21), a cryogenic liquid helium hand The valve (22) and the liquid helium Dewar pipeline, liquid nitrogen, gas nitrogen, gas helium and liquid helium are all discharged directly to the atmosphere through the fluid discharge system after passing through the heat sink system; the function of the cryogenic thermometer (21) is to monitor the heat sink system The fluid temperature at the outlet reduces the consumption of liquid nitrogen and liquid helium; the material of the system piping and valves is 316 stainless steel. 8. The liquid helium external process equipment for high pumping speed cryogenic system according to claim 1, characterized in that: the supply of liquid or gas is adjustable, and the low temperature liquid helium hand valve (3) is used to adjust the liquid helium The flow rate; the low-temperature liquid nitrogen hand valve (4) is used to adjust the liquid nitrogen flow rate; the low-temperature gas nitrogen hand valve (7) is used to adjust the gas nitrogen flow rate; the low-temperature gas helium hand valve (10) is used to adjust the gas helium flow rate.

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