Multistage compound cycle cooling unit and refrigeration system suitable for non-active cold carrier

Abstract

The utility model belongs to circulating refrigeration equipment technical field discloses a kind of multistage composite circulating cooling unit and refrigerating system suitable for non-active cold carrier.The unit includes high-temperature stage evaporator and low-temperature stage evaporator, high-temperature stage hot fluid side is provided with high-temperature stage gas-liquid separation part, the evaporation temperature of high-temperature stage hot fluid side can be between freezing point temperature and dew point temperature, the evaporation temperature of low-temperature stage hot fluid side is less than the evaporation temperature of high-temperature stage hot fluid side, so that non-active cold carrier can be gradually cooled to set temperature.Through the above setting, high-temperature stage evaporator can be continuously dewing without frost, ensure that dehumidification work continues, so that a large proportion of moisture in non-active cold carrier is removed, create favorable conditions for the work of low-temperature stage evaporator, prolong the defrosting interval time of low-temperature stage evaporator, improve the phenomenon that circulating air duct is often blocked, ensure higher circulating air volume and refrigeration effect, and then directly improve product output and economic benefit.

Description

Technical Field

[0001] This utility model relates to the field of circulating refrigeration equipment technology, and in particular to a multi-stage composite circulating cooling unit and refrigeration system suitable for non-active refrigerants. Background Technology

[0002] In industrial production, there are applications requiring cooling of powdered materials. For example, in the production of water-soluble ultra-high molecular weight powdered negative electrode binders for new energy batteries, the separate materials need to undergo a grinding process. Grinding generates high heat, causing the material temperature to rise. This temperature rise can lead to material deterioration or damage, necessitating circulating cooling and temperature control.

[0003] Because fine powders are prone to explosion upon contact with oxygen, dry nitrogen or other inert gases are typically used as a refrigerant to cool the materials. Currently, the traditional engineering approach involves using liquid nitrogen evaporation to cool powdered materials. The temperature is controlled through the heat absorption during the phase change of the liquid nitrogen during evaporation. However, the cost of compressing and condensing the vaporized nitrogen is very high, so it is generally released into the environment. When production volumes are large, this traditional method requires continuous consumption of liquid nitrogen, resulting in high operating costs.

[0004] In addition, if a circulating cooling system is used to circulate and cool the gaseous refrigerant, the possibility of frost formation on the heat exchanger must also be considered. This is because water-soluble materials have a certain water content before cooling. During the cooling process of the gaseous refrigerant, moisture easily adheres to the gaseous refrigerant. When it circulates into the cooling heat exchanger, it is easy to frost on the surface of the cooling heat exchanger, thereby blocking the circulating air duct, reducing the circulating air volume, and causing the cooling effect to decrease, which cannot meet the needs of continuous production.

[0005] Therefore, it is necessary to design a multi-stage composite circulation cooling unit and refrigeration system suitable for inactive refrigerants to solve the problems existing in the prior art. Utility Model Content

[0006] One objective of this invention is to provide a multi-stage composite circulation cooling unit suitable for inactive refrigerants, which can reduce operating costs while ensuring good cooling effect and improving the safety and stability of the cooling process for inactive refrigerants.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] A multi-stage composite circulation cooling unit suitable for non-reactive refrigerants includes a high-temperature stage evaporator and a low-temperature stage evaporator. The high-temperature stage evaporator includes a high-temperature cold fluid side and a high-temperature hot fluid side, and the low-temperature stage evaporator includes a low-temperature cold fluid side and a low-temperature hot fluid side, wherein:

[0009] Coolant is flowing in both the high-temperature stage cold fluid side and the low-temperature stage cold fluid side;

[0010] The inlet end of the high-temperature stage hot fluid side is the inlet of the inactive refrigerant. The outlet end of the high-temperature stage hot fluid side is connected to the inlet end of the low-temperature stage hot fluid side, and the outlet end of the low-temperature stage hot fluid side is the outlet of the inactive refrigerant. The high-temperature stage hot fluid side is provided with a high-temperature stage gas-liquid separation section. The evaporation temperature of the high-temperature stage hot fluid side can be between the freezing point temperature and the dew point temperature, so that after heat exchange between the high-temperature stage hot fluid side and the high-temperature stage cold fluid side, the high-temperature stage gas-liquid separation section can absorb the moisture trapped in the inactive refrigerant to separate the moisture from the inactive refrigerant. The evaporation temperature of the low-temperature stage hot fluid side is lower than that of the high-temperature stage hot fluid side, so that the inactive refrigerant can be cooled down step by step to the set temperature.

[0011] Preferably, a pressure maintaining valve is provided at the outlet end of the high-temperature stage cold fluid side. The pressure maintaining valve is used to adjust the suction pressure to ensure that the evaporation temperature of the high-temperature stage hot fluid side is between the freezing point temperature and the dew point temperature.

[0012] Preferably, the high-temperature stage evaporator includes a high-temperature stage outer shell and a high-temperature stage heat absorption module. The high-temperature stage heat absorption module is disposed inside the high-temperature stage outer shell. The inlet of the non-active refrigerant is provided at the first end of the high-temperature stage outer shell. The second end of the high-temperature stage outer shell is connected to the first end of the low-temperature stage hot fluid side. The channel inside the high-temperature stage outer shell for connecting the first end and the second end of the high-temperature stage outer shell is configured as the high-temperature stage hot fluid side. The inner wall of the high-temperature stage outer shell is configured as the high-temperature stage gas-liquid separation section. The high-temperature stage heat absorption module is configured as the heat exchange surface of the high-temperature stage cold fluid side.

[0013] Preferably, the inner wall of the high-temperature grade housing is coated with a hydrophilic coating; and / or, the bottom of the high-temperature grade housing is connected to a high-temperature grade drain valve.

[0014] Preferably, the inactive refrigerant includes nitrogen; a low-temperature gas-liquid separation section is provided on the low-temperature hot fluid side, the evaporation temperature of the low-temperature hot fluid side is lower than the freezing point temperature, after the low-temperature hot fluid side exchanges heat with the low-temperature cold fluid side, the low-temperature gas-liquid separation section can absorb the water mixed in the inactive refrigerant again, so as to separate the water from the inactive refrigerant.

[0015] Preferably, the low-temperature stage evaporator includes a low-temperature stage outer shell and a low-temperature stage heat absorption module. The low-temperature stage heat absorption module is disposed inside the low-temperature stage outer shell. The first end of the low-temperature stage outer shell is connected to the second end of the high-temperature stage outer shell. The second end of the low-temperature stage outer shell is provided with an outlet for the inactive refrigerant. The channel inside the low-temperature stage outer shell used to connect the first end and the second end of the low-temperature stage outer shell is configured as the low-temperature stage hot fluid side. The inner wall of the low-temperature stage outer shell is configured as the low-temperature stage gas-liquid separation section. The low-temperature stage heat absorption module is configured as the heat exchange surface of the low-temperature stage cold fluid side.

[0016] Preferably, the inner wall of the cryogenic stage housing is coated with a hydrophilic coating; and / or, the bottom of the cryogenic stage housing is connected to a cryogenic stage drain valve.

[0017] Preferably, the system also includes a compressor, a condenser, and a throttling valve, wherein the compressor, the condenser, and the throttling valve are connected in sequence, and the output end of the throttling valve is connected to the input end of the high-temperature stage cold fluid side and the low-temperature stage cold fluid side. The high-temperature stage cold fluid side and the low-temperature stage cold fluid side are arranged in parallel, and the output ends of the high-temperature stage cold fluid side and the low-temperature stage cold fluid side are simultaneously connected to the condenser.

[0018] Preferably, the throttling valve includes a high-temperature throttling valve and a low-temperature throttling valve, wherein the high-temperature throttling valve is connected in series with the high-temperature cold fluid side, and the low-temperature throttling valve is connected in series with the low-temperature cold fluid side.

[0019] Preferably, the system also includes an oil separator connected between the compressor's discharge port and the condenser's input port, with the oil separator's outlet connected to the compressor's inlet port.

[0020] And / or, it also includes a gas-liquid separator connected to the suction port of the compressor;

[0021] And / or, it also includes a drying filter connected at the output of the condenser.

[0022] Another objective of this invention is to provide a refrigeration system that, by employing the aforementioned multi-stage composite circulation cooling unit suitable for inactive refrigerants, can reduce the number of defrost cycles, extend the defrost interval, prolong the continuous operation time of the system, increase product output and economic benefits, and maintain a high level of safety during the production process.

[0023] To achieve this objective, the present invention adopts the following technical solution:

[0024] The refrigeration system includes a material refrigeration cycle unit and the aforementioned multi-stage composite cycle cooling unit suitable for inactive refrigerants. The material refrigeration cycle unit includes a heat release side, and the inlet end of the heat release side is connected to the outlet of the inactive refrigerant of the multi-stage composite cycle cooling unit.

[0025] The beneficial effects of this utility model are:

[0026] In the multi-stage composite circulation cooling unit for non-reactive refrigerants provided by this utility model, the gas temperature on the high-temperature stage heat fluid side of the high-temperature stage evaporator will not fall below the freezing point. This allows the high-temperature stage evaporator to continuously condense without frosting, ensuring continuous dehumidification. A large proportion of the moisture in the non-reactive refrigerant is removed, creating favorable conditions for the operation of the low-temperature stage evaporator and extending its defrosting interval. This improves upon the traditional heat exchanger's tendency to frost after short-term operation and require frequent defrosting, making it less prone to frost formation and eliminating the need for frequent defrosting during long-term operation. It also extends the unit's continuous operating time and reduces the frequent blockage of the circulating air duct, ensuring higher circulating air volume and cooling effect, thereby directly increasing product output and economic benefits.

[0027] The refrigeration system provided by this invention can reduce the number of defrost cycles and extend the defrost interval, thereby extending the system's continuous operating time, improving product output and economic efficiency, and maintaining a high level of safety during the production process. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a multi-stage composite circulation cooling unit suitable for non-active refrigerants, provided by an embodiment of this utility model.

[0029] In the picture:

[0030] 1. High-temperature stage evaporator; 101. High-temperature stage hot fluid side; 102. High-temperature stage cold fluid side; 11. High-temperature stage outer casing; 12. High-temperature stage drain valve; 13. Pressure maintaining valve; 2. Low-temperature stage evaporator; 201. Low-temperature stage hot fluid side; 202. Low-temperature stage cold fluid side; 21. Low-temperature stage outer casing; 22. Low-temperature stage drain valve; 3. Compressor; 4. Condenser; 51. High-temperature stage throttle valve; 52. Low-temperature stage throttle valve; 6. Oil separator; 7. Dryer filter; 8. Gas-liquid separator; 91. Liquid three-way valve; 92. Gas three-way valve; 1000. Inlet temperature sensor; 2000. Outlet temperature sensor. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0032] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0033] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0034] In the description of this embodiment, the terms "upper," "lower," "right," and "left," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0035] The following is in conjunction with the appendix Figure 1 The present invention will be described in detail with specific implementation methods to illustrate the technical solution provided by this utility model.

[0036] refer to Figure 1 As shown, this utility model provides a multi-stage composite circulation cooling unit suitable for non-active refrigerants. The unit includes a high-temperature stage evaporator 1 and a low-temperature stage evaporator 2. The high-temperature stage evaporator 1 includes a high-temperature stage cold fluid side 102 and a high-temperature stage hot fluid side 101. The low-temperature stage evaporator 2 includes a low-temperature stage cold fluid side 202 and a low-temperature stage hot fluid side 201.

[0037] In this embodiment, coolant flows in both the high-temperature stage cold fluid side 102 and the low-temperature stage cold fluid side 202. The inlet end of the high-temperature stage hot fluid side 101 is the inlet of the inactive refrigerant, and the outlet end of the high-temperature stage hot fluid side 101 is connected to the inlet end of the low-temperature stage hot fluid side 201. The outlet end of the low-temperature stage hot fluid side 201 is the outlet of the inactive refrigerant. The high-temperature stage hot fluid side 101 is provided with a high-temperature stage gas-liquid separation section. The evaporation temperature of the high-temperature stage hot fluid side 101 can be between the freezing point temperature and the dew point temperature, so that after the high-temperature stage hot fluid side 101 and the high-temperature stage cold fluid side 102 exchange heat, the high-temperature stage gas-liquid separation section can absorb the water mixed in the inactive refrigerant to separate the water from the inactive refrigerant. The evaporation temperature of the low-temperature stage hot fluid side 201 is lower than the evaporation temperature of the high-temperature stage hot fluid side 101, so that the inactive refrigerant can be cooled down step by step to the set temperature.

[0038] With the above settings, the gas temperature on the high-temperature hot fluid side 101 of the high-temperature evaporator 1 will not fall below the freezing point, thus enabling continuous condensation without frost formation in the high-temperature evaporator 1. This ensures continuous dehumidification and removes a large proportion of moisture from the inactive refrigerant, creating favorable conditions for the operation of the low-temperature evaporator 2. It also extends the defrosting interval of the low-temperature evaporator 2, improving the traditional heat exchanger's tendency to frost after short periods of operation and require frequent defrosting. This transforms the problem into one where frost is less likely to form during long-term operation and frequent defrosting is unnecessary, extending the unit's continuous operating time. Furthermore, it improves the problem of frequent blockages in the circulating air duct, ensuring higher circulating air volume and cooling effect, thereby directly increasing product output and economic benefits.

[0039] For example, in this embodiment, the unit can circulate cooling for powdered materials in industrial production processes, such as water-soluble ultra-high molecular weight powder-type negative electrode binders used in new energy batteries. By cooling and controlling the temperature, the temperature rise of the negative electrode binder during grinding can be reduced, thereby improving the phenomenon of material deterioration or damage. Furthermore, since fine powders are prone to explosion when exposed to oxygen, using an inactive refrigerant as a gaseous refrigerant can effectively avoid safety accidents such as explosions. This invention does not limit the type of inactive refrigerant; for example, the inactive refrigerant includes any one of nitrogen or inert gases.

[0040] Preferably, nitrogen is used as the inactive refrigerant. The temperature of the powdered material is controlled by the heat absorption of phase change during the evaporation of liquid nitrogen. In addition, the atmospheric pressure evaporation temperature of liquid nitrogen is about -196°C, which is far below the dew point of water. Therefore, when water condenses in the high-temperature evaporator 1, the inactive refrigerant can still remain in a gaseous state and achieve separation from the water.

[0041] Specifically, in this embodiment, the high-temperature evaporator 1 includes a high-temperature shell 11 and a high-temperature heat absorption module. The high-temperature shell 11 is equipped with a high-temperature heat absorption module. The first end of the high-temperature shell 11 is provided with an inlet for an inactive refrigerant. The second end of the high-temperature shell 11 is connected to the first end of the low-temperature hot fluid side 201. The channel inside the high-temperature shell 11 for connecting the first end and the second end of the high-temperature shell 11 is set as the high-temperature hot fluid side 101. The inner wall of the high-temperature shell 11 is set as a high-temperature gas-liquid separation section. The high-temperature heat absorption module is set as the heat exchange surface of the high-temperature cold fluid side 102. With the above configuration, the high-temperature heat absorption module can directly conduct heat with the inactive refrigerant (nitrogen) inside the high-temperature stage shell 11. During this process, the moisture in the inactive refrigerant condenses and adheres to the inner wall surface of the high-temperature stage shell 11. Under its own gravity, it can overcome the surface tension and accumulate along the inner wall area at the bottom of the high-temperature stage shell 11. After the inactive refrigerant cools down, it can continue to be transported to the low-temperature stage evaporator 2 for further cooling, thereby achieving the effect of separating the inactive refrigerant and a large proportion of moisture in the high-temperature stage evaporator 1.

[0042] In this embodiment, a high-temperature stage drain valve 12 is connected to the bottom of the high-temperature stage housing 11. The high-temperature stage drain valve 12 can drain the water accumulated at the bottom of the high-temperature stage housing 11 in a timely manner, reducing the impact on the purity of the inactive refrigerant.

[0043] In this embodiment, the inner wall of the high-temperature shell 11 is coated with a hydrophilic coating, which helps the condensed water to overcome surface tension and be discharged as quickly as possible.

[0044] Optionally, in this embodiment, a pressure maintaining valve 13 is also provided at the outlet end of the high-temperature stage cold fluid side 102. The function of the pressure maintaining valve 13 is to maintain a stable suction pressure through automatic thermodynamic control or PID calculation control, and indirectly control the evaporation temperature of the high-temperature stage hot fluid side 101 to be above 0°C, so that the evaporation temperature of the high-temperature stage hot fluid side 101 is between the freezing point temperature and the dew point temperature, thereby enabling the high-temperature stage evaporator 1 to continuously operate with condensation and avoid frosting operation.

[0045] Specifically, in this embodiment, a low-temperature gas-liquid separation section is provided on the low-temperature hot fluid side 201. The evaporation temperature of the low-temperature hot fluid side 201 is lower than the freezing point. After heat exchange between the low-temperature hot fluid side 201 and the low-temperature cold fluid side 202, the low-temperature gas-liquid separation section can absorb the moisture trapped in the inactive refrigerant again, thereby achieving the separation of moisture from the inactive refrigerant. It should be noted that since the temperature of nitrogen needs to be reduced to about -40°C to meet the temperature requirements of the refrigerant gas for powdered materials, it is necessary to cool the nitrogen to the required temperature in the low-temperature evaporator 2. By setting the evaporation temperature of the low-temperature hot fluid side 201 below the freezing point (0°C), after heat exchange between the low-temperature hot fluid side 201 and the low-temperature cold fluid side 202, the small amount of moisture remaining in the nitrogen will frost and be absorbed by the low-temperature gas-liquid separation section, so that the nitrogen flowing out from the outlet of the inactive refrigerant maintains a high degree of dryness.

[0046] More specifically, in this embodiment, the low-temperature evaporator 2 includes a low-temperature shell 21 and a low-temperature heat absorption module. The low-temperature heat absorption module is disposed inside the low-temperature shell 21. The first end of the low-temperature shell 21 is connected to the second end of the high-temperature shell 11. The second end of the low-temperature shell 21 is provided with an outlet for an inactive refrigerant. The channel inside the low-temperature shell 21 used to connect the first end and the second end of the low-temperature shell 21 is configured as a low-temperature hot fluid side 201. The inner wall of the low-temperature shell 21 is configured as a low-temperature gas-liquid separation section. The low-temperature heat absorption module is configured as a heat exchange surface of the low-temperature cold fluid side 202.

[0047] With the above configuration, the nitrogen gas flowing out from the high-temperature evaporator 1 enters the low-temperature evaporator 2 and can directly exchange heat with the low-temperature heat absorption module inside the low-temperature shell 21, thereby maintaining a high heat exchange efficiency. After heat exchange, the dry nitrogen gas cooled to the set temperature (around -40℃) can flow out from the second end of the low-temperature shell 21 in an orderly manner and mix with the powdered material. The residual moisture in the nitrogen gas will frost and adhere to the inner wall surface of the low-temperature shell 21, so as to achieve effective separation from the nitrogen gas. The structure is simple, easy to use, and can achieve a good separation effect.

[0048] Optionally, the inner wall of the low-temperature stage housing 21 is coated with a hydrophilic coating. It should be noted that this hydrophilic coating possesses both moisture absorption and low ice adhesion properties. It can actively absorb moisture in humid environments and form a self-lubricating water layer in low-temperature environments, thereby significantly reducing the adhesion between ice and the surface, making the ice layer easier to slide off, and further extending the defrosting interval. For example, this hydrophilic coating can be a polyethylene glycol-based hydrophilic anti-icing coating. The principle is to prepare the hydrophilic coating by reacting polyethylene glycol diglycidyl ether with diamines via a sol-gel method. In low-temperature environments, the coating absorbs water and swells, forming a loose ice layer between the ice layer and the coating, effectively weakening the bonding force between the ice and the coating, allowing the ice to slide off the coating under its own gravity.

[0049] In other parallel embodiments, the hydrophilic coating may also be a water-lubricated hydrophilic polymer coating (hydrogel type), etc. Therefore, any coating material that can achieve the dual effects of moisture absorption and low ice adhesion is within the protection scope of this utility model.

[0050] Furthermore, in this embodiment, a low-temperature stage drain valve 22 is connected to the bottom of the low-temperature stage housing 21. When opened, it can discharge the ice deposited at the bottom of the low-temperature stage housing 21 to reduce the impact on the nitrogen dryness.

[0051] It should be further noted that in this embodiment, both the high-temperature stage evaporator 1 and the low-temperature stage evaporator 2 employ indirect heat exchangers, allowing heat exchange between the high-temperature hot fluid side 101 and the high-temperature cold fluid side 102, and between the low-temperature hot fluid side 201 and the low-temperature cold fluid side 202, through convection, ensuring sufficient heat exchange and significant heat exchange effect. Exemplarily, the high-temperature stage evaporator 1 and the low-temperature stage evaporator 2 can be finned tube heat exchangers or plate heat exchangers. The high-temperature stage heat-absorbing module in the high-temperature stage evaporator 1 has a smaller fin spacing, which can be 2mm-4mm; the low-temperature stage heat-absorbing module in the low-temperature stage evaporator 2 adopts a larger fin spacing design. Based on the customer's process requirements, continuous operating time requirements, and the moisture content of the customer's materials, the fin spacing is preferably 8mm-32mm. This variable fin spacing design for the high-temperature and low-temperature heat-absorbing modules further extends the unit's continuous operating time and shortens the defrosting time.

[0052] Specifically, in this embodiment, the unit further includes a compressor 3, a condenser 4, and a throttling valve. The compressor 3, condenser 4, and throttling valve are connected in sequence, and the output end of the throttling valve is connected to the input ends of the high-temperature stage cold fluid side 102 and the low-temperature stage cold fluid side 202. The high-temperature stage cold fluid side 102 and the low-temperature stage cold fluid side 202 are arranged in parallel, and the output ends of the high-temperature stage cold fluid side 102 and the low-temperature stage cold fluid side 202 are simultaneously connected to the condenser 4. Through the above arrangement, the high-temperature stage evaporator 1 and the low-temperature stage evaporator 2 can share a single compressor 3, condenser 4, and throttling valve, thereby saving costs, being highly economical and practical, having a small volume ratio, and being easy to use.

[0053] Optionally, in this embodiment, an oil separator 6 is also connected between the exhaust port of the compressor 3 and the input end of the condenser 4. The oil outlet of the oil separator 6 is connected to the oil inlet of the compressor 3, so that the trace amount of oil leaking from the exhaust port of the compressor 3 can be intercepted by the oil separator 6. On the one hand, this can improve the purity of the coolant delivered to the condenser 4, reduce impurities, and ensure the cooling effect. On the other hand, by refilling the oil intercepted in the oil separator 6 into the compressor 3, a closed-loop circulation of oil is achieved, ensuring the lubrication requirements of the compressor 3, thereby reducing the oil replenishment frequency and the system oil carryover rate, and extending the service life of the compressor 3.

[0054] In this embodiment, the throttling valve includes a high-temperature throttling valve 51 and a low-temperature throttling valve 52. The high-temperature throttling valve 51 is connected in series with the high-temperature cold fluid side 102, and the low-temperature throttling valve 52 is connected in series with the low-temperature cold fluid side 202. The high-temperature throttling valve 51 can independently regulate the flow rate of the coolant flowing to the high-temperature cold fluid side 102, thereby achieving precise regulation of the temperature of the inactive refrigerant in the high-temperature hot fluid side 101. Similarly, the low-temperature throttling valve 52 can independently regulate the flow rate of the coolant flowing to the low-temperature cold fluid side 202, thereby achieving precise regulation of the temperature of the inactive refrigerant in the low-temperature hot fluid side 201. Thus, through the synergistic effect of the high-temperature throttling valve 51 and the low-temperature throttling valve 52, the heat exchange process of the high-temperature evaporator 1 and the low-temperature evaporator 2 is dynamically stabilized, ensuring that the nitrogen output from the low-temperature evaporator 2 remains dry and reaches the set temperature.

[0055] Optionally, in this embodiment, a dryer filter 7 is also connected to the output end of the condenser 4. The dryer filter 7 can remove solid particles (such as welding slag, metal shavings, dust) and oil stains from the coolant, thereby purifying the coolant, preventing the high-temperature throttling valve 51 and the low-temperature throttling valve 52 from becoming clogged, and avoiding refrigeration interruption.

[0056] Optionally, in this embodiment, a gas-liquid separator 8 is connected to the suction port of the compressor 3. The gas-liquid separator 8 can separate the coolant gas flowing from the output ends of the high-temperature stage cold fluid side 102 and the low-temperature stage cold fluid side 202, and discharge the coolant liquid adhering inside, so as to reduce the "liquid slugging" phenomenon of the compressor 3 and ensure good compression performance of the compressor 3. In addition, the gas-liquid separator 8 also serves as a container for storing coolant liquid. When the stored amount reaches a certain level, the coolant liquid can be discharged to the outside. The operator can then collect this portion of coolant liquid and continue to put it back into the unit for recycling, thereby avoiding waste of coolant.

[0057] Optionally, in this embodiment, the unit further includes a three-way valve assembly, which includes a liquid three-way valve 91 and a gas three-way valve 92. The liquid three-way valve 91 is connected between the output end of the dryer filter 7, the input end of the low-temperature stage throttle valve 52, and the input end of the high-temperature stage throttle valve 51. The gas three-way valve 92 is also connected between the output end of the low-temperature stage cold fluid side 202, the output end of the high-temperature stage cold fluid side 102, and the input end of the gas-liquid separator 8. By configuring the liquid three-way valve 91 and the gas three-way valve 92, under certain conditions, the high-temperature stage throttle valve 51 and the low-temperature stage throttle valve 52 can assist in regulating the flow rate of the coolant, resulting in higher precision in coolant regulation and more accurate temperature control of nitrogen. Furthermore, by shutting off the pipelines equipped with the high-temperature stage cold fluid side 102 or the low-temperature stage cold fluid side 202, maintenance personnel can easily inspect and maintain the shut-off high-temperature stage evaporator 1 or low-temperature stage evaporator 2, and the safety risks are reduced.

[0058] Optionally, in this embodiment, an inlet temperature sensor 1000 is provided at the inlet of the inactive refrigerant, and an outlet temperature sensor 2000 is provided at the outlet of the inactive refrigerant. The inlet temperature sensor 1000 can detect the temperature of nitrogen flowing into the high-temperature stage hot fluid side 101 in real time. The pressure maintaining valve 13 and / or the high-temperature stage throttle valve 51 can adjust the flow rate of the coolant in a timely manner by controlling the valve opening according to the detection results. The outlet temperature sensor 2000 can detect the temperature of nitrogen flowing out of the low-temperature stage hot fluid side 201 in real time. The low-temperature stage throttle valve 52 can further adjust the flow rate of the coolant in a timely manner by controlling the valve opening according to the detection results, thereby ensuring the dynamic stability of the nitrogen cooling process in the high-temperature stage evaporator 1 and the low-temperature stage evaporator 2.

[0059] The imported temperature sensor 1000 is connected to the pressure maintaining valve 13 and / or the high-temperature throttle valve 51, and the outlet temperature sensor 2000 is connected to the low-temperature throttle valve 52, which reduces human intervention and makes the flow regulation of coolant more accurate.

[0060] This utility model embodiment also provides a refrigeration system, including a material refrigeration circulation unit and the multi-stage composite circulation cooling unit for inactive refrigerants described above. The material circulation refrigeration unit includes a material heat exchanger, which has an absorption side and a release side. A heat-absorbing medium flows in the heat-absorbing side. The inlet end of the release side is connected to the outlet of the inactive refrigerant of the multi-stage composite circulation cooling unit. Nitrogen gas flowing out of the outlet of the inactive refrigerant enters the release side and combines with the material to be cooled, so that the nitrogen gas can carry the material to be cooled and exchange heat with the heat-absorbing side at the heat exchange surface, thereby achieving material cooling. The cooled material is discharged from the outlet end of the release side and can be separated from the nitrogen gas by other filtration means such as a cyclone separator, so that the nitrogen gas can circulate to the inlet of the inactive refrigerant for further cooling and drying, and then be reused, reducing operating costs.

[0061] The refrigeration system provided in this embodiment, due to the multi-stage composite circulation cooling unit mentioned above, can reduce the number of defrost cycles and extend the defrost interval, thereby extending the continuous working time of the system, improving product output and economic benefits, and maintaining a high level of safety in the production process.

[0062] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0063] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A multi-stage composite circulation cooling unit suitable for non-reactive refrigerants, characterized in that, It includes a high-temperature stage evaporator (1) and a low-temperature stage evaporator (2), wherein the high-temperature stage evaporator (1) includes a high-temperature stage cold fluid side (102) and a high-temperature stage hot fluid side (101), and the low-temperature stage evaporator (2) includes a low-temperature stage cold fluid side (202) and a low-temperature stage hot fluid side (201), wherein: Coolant is flowing in both the high-temperature stage cold fluid side (102) and the low-temperature stage cold fluid side (202); The inlet of the high-temperature stage hot fluid side (101) is the inlet of the inactive refrigerant. The outlet of the high-temperature stage hot fluid side (101) is connected to the inlet of the low-temperature stage hot fluid side (201). The outlet of the low-temperature stage hot fluid side (201) is the outlet of the inactive refrigerant. The high-temperature stage hot fluid side (101) is provided with a high-temperature stage gas-liquid separation section. The evaporation temperature of the high-temperature stage hot fluid side (101) can be between the freezing point temperature and the dew point temperature, so that after the high-temperature stage hot fluid side (101) exchanges heat with the high-temperature stage cold fluid side (102), the high-temperature stage gas-liquid separation section can absorb the water mixed in the inactive refrigerant, so as to separate the water from the inactive refrigerant. The evaporation temperature of the low-temperature stage hot fluid side (201) is lower than the evaporation temperature of the high-temperature stage hot fluid side (101), so that the inactive refrigerant can be cooled down step by step to the set temperature.

2. The multi-stage composite circulation cooling unit suitable for non-reactive refrigerants according to claim 1, characterized in that, The outlet end of the high-temperature cold fluid side (102) is provided with a pressure maintaining valve (13), which is used to adjust the suction pressure to ensure that the evaporation temperature of the high-temperature hot fluid side (101) is between the freezing point temperature and the dew point temperature.

3. The multi-stage composite circulation cooling unit suitable for non-reactive refrigerants according to claim 1, characterized in that, The high-temperature evaporator (1) includes a high-temperature shell (11) and a high-temperature heat absorption module. The high-temperature heat absorption module is disposed inside the high-temperature shell (11). The inlet of the non-active refrigerant is disposed at the first end of the high-temperature shell (11). The second end of the high-temperature shell (11) is connected to the first end of the low-temperature hot fluid side (201). The channel inside the high-temperature shell (11) for connecting the first end of the high-temperature shell (11) and the second end of the high-temperature shell (11) is disposed as the high-temperature hot fluid side (101). The inner wall of the high-temperature shell (11) is disposed as the high-temperature gas-liquid separation section. The high-temperature heat absorption module is disposed as the heat exchange surface of the high-temperature cold fluid side (102).

4. The multi-stage composite circulation cooling unit suitable for non-reactive refrigerants according to claim 3, characterized in that, The inner wall of the high-temperature housing (11) is coated with a hydrophilic coating; and / or, the bottom of the high-temperature housing (11) is connected to a high-temperature drain valve (12).

5. The multi-stage composite circulation cooling unit suitable for non-reactive refrigerants according to claim 3, characterized in that, The inactive refrigerant includes nitrogen; the low-temperature stage hot fluid side (201) is provided with a low-temperature stage gas-liquid separation section. The evaporation temperature of the low-temperature stage hot fluid side (201) is lower than the freezing point temperature. After the low-temperature stage hot fluid side (201) exchanges heat with the low-temperature stage cold fluid side (202), the low-temperature stage gas-liquid separation section can absorb the water mixed in the inactive refrigerant again, so as to separate the water from the inactive refrigerant.

6. The multi-stage composite circulation cooling unit suitable for non-reactive refrigerants according to claim 5, characterized in that, The low-temperature stage evaporator (2) includes a low-temperature stage outer shell (21) and a low-temperature stage heat absorption module. The low-temperature stage heat absorption module is disposed inside the low-temperature stage outer shell (21). The first end of the low-temperature stage outer shell (21) is connected to the second end of the high-temperature stage outer shell (11). The second end of the low-temperature stage outer shell (21) is provided with an outlet for the inactive refrigerant. The channel inside the low-temperature stage outer shell (21) used to connect the first end of the low-temperature stage outer shell (21) and the second end of the low-temperature stage outer shell (21) is configured as the low-temperature stage hot fluid side (201). The inner wall of the low-temperature stage outer shell (21) is configured as the low-temperature stage gas-liquid separation section. The low-temperature stage heat absorption module is configured as the heat exchange surface of the low-temperature stage cold fluid side (202).

7. The multi-stage composite circulation cooling unit suitable for non-reactive refrigerants according to claim 6, characterized in that, The inner wall of the low-temperature stage housing (21) is coated with a hydrophilic coating; and / or, the bottom of the low-temperature stage housing (21) is connected to a low-temperature stage drain valve (22).

8. The multi-stage composite circulation cooling unit suitable for non-reactive refrigerants according to claim 1, characterized in that, It also includes a compressor (3), a condenser (4) and a throttle valve. The compressor (3), the condenser (4) and the throttle valve are connected in sequence, and the output end of the throttle valve is connected to the input end of the high-temperature stage cold fluid side (102) and the low-temperature stage cold fluid side (202). The high-temperature stage cold fluid side (102) and the low-temperature stage cold fluid side (202) are arranged in parallel, and the output ends of the high-temperature stage cold fluid side (102) and the low-temperature stage cold fluid side (202) are simultaneously connected to the condenser (4).

9. The multi-stage composite circulation cooling unit for non-reactive refrigerants according to claim 8, characterized in that, The throttle valve includes a high-temperature throttle valve (51) and a low-temperature throttle valve (52). The high-temperature throttle valve (51) is connected in series with the high-temperature cold fluid side (102), and the low-temperature throttle valve (52) is connected in series with the low-temperature cold fluid side (202).

10. The multi-stage composite circulation cooling unit for non-reactive refrigerants according to claim 8, characterized in that, It also includes an oil separator (6), which is connected between the exhaust port of the compressor (3) and the input end of the condenser (4), and the oil outlet of the oil separator (6) is connected to the oil inlet of the compressor (3). And / or, also includes a gas-liquid separator (8) connected to the suction port of the compressor (3); And / or, it also includes a drying filter (7) connected at the output of the condenser (4).

11. A refrigeration system, characterized in that, The invention includes a material refrigeration cycle unit and a multi-stage composite cycle cooling unit suitable for inactive refrigerants as described in any one of claims 1-10. The material refrigeration cycle unit includes a heat release side, and the inlet end of the heat release side is connected to the outlet of the inactive refrigerant of the multi-stage composite cycle cooling unit.

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