Low-temperature refrigerating system utilizing centrifugal compressor and turbo expander

Abstract

The invention discloses a low-temperature refrigerating system utilizing a centrifugal compressor and a turbo expander, which consists of the centrifugal compressor, the turbo expander, a cold box barrel, a vacuum pump, a cooler, a heat exchanger, a three-way valve, a temperature monitor, a pressure monitor, a monitoring control system, a gas storage tank, a pipeline and a circuit, the centrifugal compressor and the turbo expander are supported by foil dynamic pressure gas bearings, the friction loss is small, the service life cycle is basically free of maintenance, the centrifugal compressor and the turbo expander can run completely without oil in the working process, the cleanliness is high, mechanical energy generated by the pressurization end of the turbo expander is utilized by the system for reutilization, and the energy consumption is low. And the energy utilization rate is increased, and high efficiency is achieved.

Description

Technical Field

[0001] This invention belongs to the field of cryogenic refrigeration technology, and specifically relates to a cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander. Background Technology

[0002] In long-term production practice and daily life, people have discovered that many phenomena are closely related to temperature. Scientific research often requires artificial low-temperature environments. For example, in order to study the performance of engines, cars, tanks and cannons used in cold conditions, it is necessary to conduct simulation tests under the corresponding environmental conditions. The control instruments in aerospace instruments, rockets and missiles also need to undergo performance tests on the ground under simulated high-altitude environments. Cryogenic refrigeration systems provide the necessary low-temperature and low-pressure environmental conditions for such tests.

[0003] Since the 1950s, gas refrigerators have gradually been developed that utilize the adiabatic expansion and adiabatic venting processes of gases to obtain low temperatures. Refrigeration technologies that utilize the adiabatic expansion process of gases include the reverse Brayton cycle and the reverse Stirling cycle. In the reverse Brayton cycle, the turbine expander is a commonly used key refrigeration machine, and its efficiency and operating performance play a crucial role in the economy and long-term continuous and reliable operation of the device. The performance and operating mode of the turbine expander have a significant impact on the working efficiency of the refrigeration system.

[0004] To improve the efficiency and lifespan of refrigeration systems, this invention proposes a cryogenic refrigeration system using a centrifugal compressor and a turboexpander. Both the compressor and turboexpander used in this system are supported by gas bearings, requiring virtually no maintenance and no lubrication during operation. The system operates very cleanly, greatly improving efficiency and extending lifespan.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key or important components or to describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0007] This invention aims to provide a cryogenic refrigeration system utilizing a centrifugal compressor and a turboexpander. The system achieves different refrigeration temperatures by using different cooling capacities provided by different turboexpanders. An external refrigeration system utilizes the generated cooling capacity. The cryogenic refrigeration unit operates in a vacuum environment, which can effectively reduce the cooling loss of gas molecules during the refrigeration process. Both the compressor and the turboexpander are supported by gas bearings, resulting in low friction loss and virtually maintenance-free lifespan. The compressor is placed on a vacuum cold box and is cooled by liquid cooling. The system is a skid-mounted design, achieving complete oil-free operation, high cleanliness, low friction loss, and virtually maintenance-free lifespan. The system utilizes the booster end of the turboexpander to recompress the gas, achieving energy recovery and utilization, making it highly energy-efficient, green, and efficient.

[0008] To achieve the above objectives, the present invention proposes the following technical solution: The cryogenic refrigeration system consists of a compressor (1), a cooler (2), a monitoring and control system (3), three-way valves (4)(16)(17)(18)(19)(20), a check valve (5), a cold box cylinder (6), a pressure monitor (7), a temperature monitor (8), a heat exchanger (9), a turbo expander (10), an external cooling system (11), a vacuum pump (12), a gas storage tank (13), a pipeline (14), a pipeline (15), and wiring. The compressor (1) is an oil-free compressor, and both the compressor (10) and the turbo expander (10) use gas bearings. With low friction loss and minimal maintenance throughout its lifespan, the system is completely oil-free and very clean during operation. The system's working medium is divided into two types: rare gas and air. When the working medium is rare gas, the system adopts a closed-loop circulation mode, and when the working medium is air, the system adopts an open-loop circulation mode. This cryogenic refrigeration system utilizes the mechanical energy generated at the expansion end of the turbine expander to drive the booster wheel at the booster end to rotate, thereby performing secondary compression on the second gas stream that flows out through the three-way valve (4) into the second pipeline (15). After compression, the gas stream re-enters the expansion end of the turbine expander through the cooler (2), thus completing the energy recovery and utilization, which is highly efficient.

[0009] A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander further includes the following steps: Step 1: Working gas compression and pre-cooling. After the working gas is compressed into high temperature and high pressure gas by the compressor, it is pre-cooled into room temperature and high pressure gas by the cooler and flows through the pipeline into the high temperature flow channel of the heat exchanger. Step 2: Cooling of room temperature high-pressure gas. The room temperature high-pressure gas is cooled by heat exchanger and then enters the expansion end of the turbine expander to cool down into low temperature low-pressure gas. Step 3: Low-temperature and low-pressure gas circulation. The low-temperature and low-pressure gas enters the cooling channel of the heat exchanger to cool the room-temperature and high-pressure gas. After utilization, the gas re-enters the compressor for compression. The compressed gas is divided into a first gas stream and a second gas stream through a three-way valve. The first gas stream can directly enter the heat exchanger for heat exchange and cooling, while the second gas stream enters the blower side of the turbine expander for secondary compression, realizing energy recovery and utilization.

[0010] The present invention is characterized by:

[0011] The present invention provides a cryogenic refrigeration system using a centrifugal compressor and a turbine expander. The internal environment of the cold box cylinder is a vacuum environment, which can reduce the loss of cold energy by gas molecules during the refrigeration and cooling process, and reduce energy consumption.

[0012] The present invention discloses a cryogenic refrigeration system utilizing a centrifugal compressor and a turbo expander. The compressor and turbo expander can be replaced according to changes in system operating requirements. The compressor is placed on a vacuum cold box, and the turbo expander is connected to the cold box cylinder through flange joints or threads. The cryogenic refrigeration system is a skid-mounted system.

[0013] In this invention, a gas stream that has been used by an external cooling system in a cryogenic refrigeration system using a centrifugal compressor and a turbo expander enters the cooling channel of a heat exchanger and is compressed again by the compressor. Then, it is divided into a first gas stream and a second gas stream by a three-way valve (4) to achieve three different circulation modes. The first gas stream enters pipe one, and the second gas stream enters pipe two.

[0014] Furthermore, the three circulation modes are divided into pressurized gas circulation mode, non-pressurized gas circulation mode, and mixed gas circulation mode.

[0015] Furthermore, the second gas stream in pipeline 2 is pressurized again at the turbo expander pressurization end, then flows through the cooler and re-enters the heat exchanger for gas circulation, thus realizing the pressurized gas circulation mode.

[0016] Furthermore, in the non-pressurized gas circulation mode, one method is to have high-pressure gas flow through a three-way valve (4) to pipeline one (14), and another method is to have high-pressure gas split into a first gas stream and a second gas stream by the three-way valve (4). The first gas stream enters the cooler for circulation through pipeline one (14), and the second gas stream enters the turbo expander pressurization end through pipeline two (15) for compression, and then enters the gas storage tank (13) for storage through the three-way valve (16).

[0017] Furthermore, the first gas stream enters the heat exchanger through pipeline one, and the second gas stream enters the turboexpander pressurization end through pipeline two for further pressurization. After cooling, it mixes with the first gas stream in pipeline one to achieve a mixed gas circulation mode.

[0018] The present invention provides a cryogenic refrigeration system using a centrifugal compressor and a turbo expander, which can achieve the following technical effects: both the pressurized gas circulation mode and the mixed gas circulation mode utilize the mechanical energy generated by the turbo expander at the expansion end to drive the pressurizing wheel at the pressurizing end to rotate, and further compress the second gas stream that enters the second pipeline through the three-way valve. After compression, the gas enters the expansion end of the turbo expander through the cooler, thus completing the energy recovery and utilization, which is very efficient.

[0019] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0020] To more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary. For those skilled in the art, other embodiments can be derived from the provided drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of a cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander disclosed in this invention.

[0022] Attached reference numerals: Compressor-1, Cooler-2, Monitoring and Control System-3, Three-way Valve-4, Check Valve-5, Cold Box Cylinder-6, Pressure Monitor-7, Temperature Monitor-8, Heat Exchanger-9, Turbine Expander-10, External Cooling System-11, Vacuum Pump-12, Gas Receiver-13, Pipeline 1-14, Pipeline 2-15, Three-way Valve-16, 17, 18, 19, 20.

[0023] Figure 2 This is a schematic diagram of the process of Embodiment 6 of a cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander disclosed in this invention.

[0024] Attached reference numerals: Compressor-1, Cooler-2, Monitoring and Control System-3, Three-way Valve-4, Check Valve-5, Cold Box Cylinder-6, Pressure Monitor-7, Temperature Monitor-8, Heat Exchanger-9, Turbine Expander-10, External Cooling System-11, Vacuum Pump-12, Gas Storage Tank-13, Pipeline 1-14, Pipeline 2-15, Three-way Valve-16, 17, 18, 19, 20, 21, Check Valve-22, Buffer Tank-23, Pipeline 3-24. Detailed Implementation

[0025] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0026] Example 1

[0027] As shown in the figure, a cryogenic refrigeration system utilizing a centrifugal compressor and a turboexpander has a system where the pressurization process takes place outside the cold box cylinder, the cryogenic refrigeration cycle takes place inside the cold box cylinder, and the cryogenic gas enters the external refrigeration system through a three-way valve to achieve the utilization of cooling capacity.

[0028] In this embodiment, the refrigerant is air, and the circulation mode is open circulation. The vacuum pump is turned on before the system starts working to provide a vacuum environment inside the cold box cylinder, reducing the loss of cooling capacity of gas molecules during operation. At room temperature and pressure gas enters the compressor (1) through the gas inlet. After being compressed by the compressor, it becomes high temperature and high pressure gas and enters the cooler (2). The cooler pre-cools the high temperature and high pressure gas through air cooling or water cooling. The pre-cooled gas enters the cold box cylinder through a pipeline.

[0029] The pre-cooled gas enters the heat exchanger (6) high-temperature pipeline inside the cold box cylinder for cooling. After cooling, it enters the turbine expander for adiabatic expansion, thereby achieving rapid cooling and forming low-temperature, low-pressure gas. The low-temperature, low-pressure gas can directly enter the heat exchanger (9) to use its own cooling capacity to exchange heat and cool the pre-cooled gas, forming an extreme low-temperature mode. Alternatively, it can enter an external refrigeration system through a three-way valve for cooling capacity utilization.

[0030] After the cooling cycle is completed, the open-loop gas outlet in the diagram opens, and the utilized cooling gas is discharged through the outlet, completing one working cycle. The above system operates in an open-loop mode.

[0031] Example 2

[0032] In this embodiment, the refrigerant is a rare gas, the circulation method is a closed loop, and the system working mode is a non-pressurized gas circulation mode. The first working loop is similar to that in embodiment 1. After the cooling cycle ends, the open loop gas outlet is closed, the working gas re-enters the compressor for re-compression, and enters pipeline 1 through the cooler (2) for non-pressurized gas circulation. The system working mode is a closed loop.

[0033] Example 3

[0034] In this embodiment, the refrigerant is a rare gas, the circulation method is a closed loop, and the system working mode is a pressurized gas circulation mode. The first working loop is similar to that in embodiment 1. After the cooling cycle is completed, the open loop gas outlet is closed, and the working gas re-enters the compressor for re-compression. After passing through the cooler (2), it enters the turbo expander pressurization end of pipeline 2 for re-pressurization. After passing through the cooler, it enters the high-temperature flow channel of the heat exchanger for pressurized gas circulation. The system working mode is a closed loop.

[0035] Example 4

[0036] In this embodiment, the refrigerant is a rare gas, the circulation mode is a closed loop, and the system working mode is a mixed gas circulation mode. The first working loop is similar to that in embodiment 1. After the cooling cycle ends, the open loop gas outlet is closed, and the working gas re-enters the compressor for re-compression. After passing through the cooler (2), it is divided into a first gas stream and a second gas stream by a three-way valve. The first gas stream flows through pipeline one, and the second gas stream enters the turbo expander pressurization end of pipeline two for re-pressurization. After passing through the cooler, it mixes with the first gas stream. The mixed gas stream enters the high-temperature flow channel of the heat exchanger for mixed gas circulation. The system working mode is a closed loop.

[0037] Example 5

[0038] In this embodiment, the refrigerant is air, and the circulation method is a closed loop, similar to Embodiments 2, 3, and 4, achieving different working modes.

[0039] Example 6

[0040] Figure 2 This is a schematic diagram of the implementation of this embodiment. In this embodiment, the working fluid is initially compressed by the compressor (1) and then enters the buffer tank (23). The buffer tank (23) plays the role of gas collection and buffering. The high-pressure gas is cooled to room temperature by the cooler (2) and enters pipeline one (14) through the three-way valve (4) and then flows to pipeline three (24) through the three-way valve (21). At this time, the one-way valve (22) is opened and the gas directly enters the expansion end of the turbine expander (10) for adiabatic expansion to form low-temperature and low-pressure gas. This embodiment can be used to test the system performance of the room-temperature turbine expander.

[0041] The foregoing description and accompanying drawings fully illustrate embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included or substituted for parts and features of other embodiments. Embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from its scope. The scope of the present disclosure is limited only by the appended claims.

Claims

1. This invention provides a cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander, characterized in that, The cryogenic refrigeration system consists of a compressor (1), a cooler (2), a monitoring and control system (3), three-way valves (4)(16)(17)(18)(19)(20), a check valve (5), a cold box cylinder (6), a pressure monitor (7), a temperature monitor (8), a heat exchanger (9), a turbo expander (10), an external cooling system (11), a vacuum pump (12), a gas storage tank (13), pipeline one (14), pipeline two (15), and wiring. The compressor (1) is an oil-free centrifugal compressor, and both the compressor (10) and the turbo expander (10) are supported by gas bearings, resulting in low friction loss and a short service life. This system is maintenance-free and can operate completely without oil, making it very clean. The system's working medium is divided into two types: rare gas and air. When the working medium is rare gas, the system adopts a closed-loop circulation mode. When the working medium is air, the system adopts an open-loop circulation mode. This cryogenic refrigeration system uses the mechanical energy generated at the expansion end of the turbine expander to drive the pressure wheel at the pressure boosting end to work. It recompresses the second gas stream that flows out through the three-way valve (4) into the second pipeline (15). The compressed gas can then re-enter the expansion end of the turbine expander through the cooler (2), realizing energy recovery and utilization, which is very efficient.

2. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander, characterized in that: The aforementioned cryogenic refrigeration system further includes the following steps: Step 1: Working gas compression and pre-cooling. After the working gas is compressed into high temperature and high pressure gas by the compressor, it is pre-cooled into room temperature and high pressure gas by the cooler and flows through the pipeline into the high temperature flow channel of the heat exchanger. Step 2: Cooling of room temperature high-pressure gas. The room temperature high-pressure gas is cooled by heat exchanger and then enters the expansion end of the turbine expander to cool down into low temperature low-pressure gas. Step 3: Low-temperature and low-pressure gas circulation. The low-temperature and low-pressure gas enters the cooling channel of the heat exchanger to cool the normal-temperature and high-pressure gas. After being utilized, the gas re-enters the compressor for compression. The compressed gas is divided into a first gas stream and a second gas stream through a three-way valve (4). The first gas stream can directly enter the heat exchanger for heat exchange and cooling circulation, while the second gas stream enters the turboexpander's booster end for further compression, thus realizing energy recovery and utilization.

3. The cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 1, characterized in that, The low-temperature, low-pressure gas after the expansion end of the turbine expander can directly enter the cooling channel of the heat exchanger to cool the compressed high-pressure gas and achieve the extreme low-temperature mode. Alternatively, it can enter the external cooling system through the three-way valve (17), and after being cooled, it enters the cooling channel of the heat exchanger to cool the room-temperature gas and then re-enters the compressor for compression, thus realizing the cascade utilization of cooling capacity.

4. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 2, characterized in that, The system has three circulation modes: pressurized gas circulation mode, non-pressurized gas circulation mode, and mixed gas circulation mode.

5. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 3, characterized in that, There are two methods to achieve the non-pressurized gas circulation mode. The first method is that the high-pressure gas flows to the pipeline (14) through the three-way valve (4). At this time, the system only has the first gas stream circulating. The second method is that the high-pressure gas is divided into the first gas stream and the second gas stream by the three-way valve (4). The first gas stream enters the heat exchanger (9) for circulation through the pipeline (14). The second gas stream enters the turbo expander pressurization end through the pipeline (15) and is compressed. Then, it enters the gas storage tank (13) for storage through the three-way valve (16). At this time, the system is divided into the cooling cycle of the first gas stream and the pressurization cycle of the second gas stream.

6. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 3, characterized in that, When the pressurized gas circulation mode is implemented, the high-pressure gas flows through the three-way valve (4) to the second pipeline (15), enters the turbo expander pressurization end for compression, and after compression, it enters the cooler through the three-way valve (16) and then enters the heat exchanger for circulation. At this time, the system only has the second gas stream for cooling circulation.

7. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 3, characterized in that, When the mixed gas circulation mode is implemented, the first gas stream enters pipeline one, and the second gas stream enters pipeline two for compression. At this time, the gas storage tank does not collect the second gas stream. After being cooled by the cooler, the second gas stream mixes with the first gas stream to form a mixed gas stream. At this time, there is a cooling circulation of the mixed gas stream in the system.

8. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 1, characterized in that, The cold box is a closed cylinder, and the vacuum pump provides a vacuum environment for the cold box. The turbo expander and heat exchanger operate in a vacuum environment, which aims to reduce the loss of cold energy by gas molecules during the refrigeration process.

9. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 1, characterized in that, The compressor and turboexpander can be replaced according to changes in system operating requirements. The compressor and turboexpander are connected to the cold box body via flange joints or threads. The cryogenic refrigeration system is a skid-mounted system.

10. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 1, characterized in that, The compressor is placed on a vacuum cold box and uses liquid cooling. The compressor can be a 1-8 stage compressor.

11. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 1, characterized in that, The compressor is an oil-free centrifugal compressor, which can directly compress low-temperature gas, reducing the process of the low-temperature gas returning to normal temperature and eliminating the need for a temperature regulator.

12. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 1, characterized in that, Both the compressor and the turboexpander are supported by gas bearings, achieving completely oil-free cooling throughout the entire refrigeration system operation. No oil removal or return devices are required, resulting in high cleanliness.

13. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 1, characterized in that, The speeds of the compressor and the turbine expander are adjustable, and the refrigeration temperature and refrigeration capacity can be changed by altering the gas flow rate, the compressor pressure ratio, and the expander expansion ratio.

14. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 3, characterized in that, The refrigerant of the cryogenic refrigeration unit can be air, hydrogen, helium, neon, or nitrogen. When the refrigerant is hydrogen, helium, neon, or nitrogen, the system adopts a closed-loop cycle. When the refrigerant is air, the entire system adopts an open-loop cycle, which reduces refrigeration costs. The refrigeration system can also adjust the circulation mode according to the working status.

15. A cryogenic refrigeration system utilizing a centrifugal compressor and a turbine expander as described in claim 1, characterized in that, The cooling method of the cooler (2) is water cooling or air cooling.

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