Mixed refrigerant recycling and purifying system and method thereof

Abstract

The invention discloses a mixed refrigerant recycling and purifying system and method, the system comprises a Stirling cryocooler, the Stirling cryocooler is provided with a first cold end for providing a precooling temperature, a second cold end for providing a first condensation temperature and a third cold end for providing a second condensation temperature, and the first condensation temperature is higher than the second condensation temperature; the electrostatic filtering unit is thermally coupled with the first cold end and is used for removing oil from the gaseous mixed refrigerant at the precooling temperature; and the first condenser is positioned at the downstream of the electrostatic filtering unit and is thermally coupled with the second cold end. The static filtering unit is thermally coupled with the first cold end of the Stirling cryocooler, oil removal of the gaseous mixed refrigerant is achieved in the pre-cooling temperature area, meanwhile, fractional condensation of refrigerant components is achieved through the multi-stage cold end temperature provided by the Stirling cryocooler, and high-boiling-point components and low-boiling-point components are sequentially separated.

Description

Technical Field

[0001] This invention relates to the field of refrigerant technology, and in particular to a mixed refrigerant recovery and purification system and method. Background Technology

[0002] Refrigerants, especially hydrofluorocarbon (HFC) refrigerants, face increasingly stringent international environmental regulations and production quota reductions due to their high global warming potential. Against this backdrop, recycling and regenerating spent HFC refrigerants not only brings environmental benefits but is also an important way to alleviate supply shortages and ensure market demand.

[0003] However, existing refrigerant recovery and purification technologies face significant technical bottlenecks when processing mixed refrigerants, especially when separating non-azeotropic refrigerant mixtures. Non-azeotropic refrigerant mixtures consist of multiple single-component refrigerants with different boiling points. Traditional recovery methods (such as conventional distillation or simple condensation) are insufficient to efficiently separate them into reusable pure single components, resulting in the recovered mixture being unusable and causing resource waste.

[0004] Therefore, there is an urgent need in this field for a new technical solution to efficiently separate the components of non-azeotropic refrigerant mixtures and to deeply purify and precisely remove impurities such as micro-oil, thereby achieving high-value regeneration and utilization of the mixed refrigerant. Summary of the Invention

[0005] The main objective of this invention is to provide a mixed refrigerant recovery and purification system and method to solve the above-mentioned technical problems.

[0006] In a first aspect, the present invention provides a mixed refrigerant recovery and purification system, comprising:

[0007] A Stirling refrigerator, the Stirling refrigerator having a first cold end providing a pre-cooling temperature, a second cold end providing a first condensing temperature, and a third cold end providing a second condensing temperature, wherein the first condensing temperature is higher than the second condensing temperature;

[0008] An electrostatic filtration unit, which is thermally coupled to the first cold end, is used to remove oil from the gaseous mixed refrigerant at the pre-cooling temperature;

[0009] A first condenser, located downstream of the electrostatic filtration unit and thermally coupled to the second cold end, is used to condense the high-boiling-point components in the gaseous refrigerant mixture at the first condensation temperature; and

[0010] The second condenser is located downstream of the first condenser and is thermally coupled to the third cold end. The second condenser is used to condense the low-boiling-point components in the gaseous mixed refrigerant at the second condensation temperature.

[0011] The precooling temperature is higher than the first condensation temperature; the electrostatic filtration unit includes an electrostatic generator and a dust collection plate, and an ionization zone is formed between the electrostatic generator and the dust collection plate.

[0012] It also includes a first recovery tank connected to the liquid outlet of the first condenser; and a second recovery tank connected to the liquid outlet of the second condenser.

[0013] It also includes an adsorption tower located upstream of the electrostatic filtration unit, and the adsorption tower contains an adsorbent.

[0014] The system also includes a compressor located upstream of the adsorption tower and a distillation tank located upstream of the compressor; the distillation tank is equipped with a heat exchange pipe; the inlet of the compressor is connected to the gas outlet of the distillation tank, the outlet of the compressor is connected to the inlet of the heat exchange pipe, and the outlet of the heat exchange pipe is connected to the inlet of the adsorption tower.

[0015] It also includes a purity detection device disposed between the electrostatic filtration unit and the first condenser; a circulation pipeline, the inlet end of which is connected to the purity detection device and the outlet end of which is connected to the inlet of the compressor; and a control valve disposed in the circulation pipeline.

[0016] It also includes a heat recovery loop disposed between the hot end of the Stirling refrigerator and the adsorption tower, the heat recovery loop being configured to transfer waste heat from the hot end of the Stirling refrigerator to the adsorption tower.

[0017] The adsorption tower includes a first shell for containing the adsorbent and a second shell covering the outside of the first shell, with a flow chamber formed between the first shell and the second shell; the heat recovery circuit includes a circulating pump, a heat transfer medium, and a heat exchanger thermally coupled to the hot end of the Stirling refrigerator, the circulating pump being configured to drive the heat transfer medium to circulate between the heat exchanger and the flow chamber.

[0018] The system also includes a vacuum pump connected to the adsorption tower, which is configured to evacuate the adsorption tower while the adsorbent is heated in the heat recovery circuit.

[0019] Secondly, the present invention also provides a method for recovering and purifying mixed refrigerants, comprising the following steps:

[0020] The gaseous mixed refrigerant is introduced into the pretreatment unit to remove moisture and acidic substances from the gaseous mixed refrigerant;

[0021] Using the first cold end of the Stirling refrigerator, the electrostatic filter unit is cooled to a pre-cooling temperature, and the gaseous mixed refrigerant is degreased by passing through the electrostatic filter unit at the pre-cooling temperature.

[0022] The degreased gaseous mixed refrigerant is introduced into the first condenser, where the high-boiling-point components in the gaseous mixed refrigerant are condensed at the first condensation temperature provided by the second cold end of the Stirling refrigerator.

[0023] Uncondensed gaseous refrigerant mixture is introduced into a second condenser, where the low-boiling-point components of the gaseous refrigerant mixture are condensed at a second condensation temperature provided by the third cold end of the Stirling refrigerator.

[0024] The refrigerant components obtained by condensation in the first condenser and the second condenser are collected into the corresponding recovery storage tanks.

[0025] Beneficial technical effects of the present invention:

[0026] This invention achieves oil removal from gaseous refrigerant mixtures in the pre-cooling temperature zone by thermally coupling an electrostatic filtration unit with the first cold end of a Stirling refrigerator. Simultaneously, the multi-stage cold end temperature provided by the Stirling refrigerator enables staged condensation of the refrigerant components, efficiently separating high-boiling-point and low-boiling-point components sequentially. Therefore, this system can achieve efficient component separation and purification of non-azeotropic refrigerant mixtures while removing impurities, overcoming the shortcomings of traditional recovery technologies such as incomplete oil removal and low separation efficiency, thus obtaining high-purity refrigerant that can be directly reused. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a mixed refrigerant recovery and purification system provided in an embodiment of the present invention;

[0029] Figure 2 A schematic diagram of the adsorption tower in the mixed refrigerant recovery and purification system provided in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the mixed refrigerant recovery and purification method provided in an embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] In the diagram: 1-External refrigeration equipment, 2-Distillation tank, 3-First oil collection container, 4-Compressor, 5-Adsorption tower, 6-Electrostatic filtration unit, 7-First condenser, 8-Second condenser, 9-First cold end, 10-Second cold end, 11-Third cold end, 12-Stirling refrigerator, 13-Heat storage material, 14-Heat exchanger, 15-Second oil collection container, 16-Circulation pump, 20-Purity testing device, 21-First recovery storage tank, 22-Second recovery storage tank, 23-Vacuum pump, 24-Circulation pipeline, 27-First shell, 28-Second shell, 29-Flow chamber. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0035] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0036] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0037] Please also refer to Figures 1-2This invention provides a mixed refrigerant recovery and purification system designed to efficiently separate and purify non-azeotropic refrigerant mixtures containing impurities (such as lubricating oil). The system includes a Stirling refrigerator 12 having a first cold end 9 providing a pre-cooling temperature, a second cold end 10 providing a first condensing temperature, and a third cold end 11 providing a second condensing temperature, wherein the first condensing temperature is higher than the second condensing temperature; an electrostatic filter unit 6 thermally coupled to the first cold end 9 for removing oil from the gaseous mixed refrigerant at the pre-cooling temperature; a first condenser 7 located downstream of the electrostatic filter unit 6 and thermally coupled to the second cold end 10, for condensing high-boiling-point components in the gaseous mixed refrigerant at the first condensing temperature; and a second condenser 8 located downstream of the first condenser 7 and thermally coupled to the third cold end 11, for condensing low-boiling-point components in the gaseous mixed refrigerant at the second condensing temperature. It should be noted that high-boiling-point components refer to those components in a gaseous refrigerant mixture that can be condensed into liquids at a relatively high temperature (i.e., the first condensation temperature); low-boiling-point components, on the other hand, remain gaseous at that temperature and require a lower temperature (i.e., the second condensation temperature) to be condensed.

[0038] In this embodiment, the system includes a Stirling refrigerator 12, an electrostatic filter unit 6, a first condenser 7, and a second condenser 8.

[0039] Specifically, the Stirling refrigerator 12 is the refrigeration component of this system, capable of generating multiple stable and controllable low-temperature zones at different locations through the periodic compression and expansion of its internal working fluid. In this embodiment, the Stirling refrigerator 12 has three independent cold ends: a first cold end 9, a second cold end 10, and a third cold end 11. It should be noted that the term "cold end" here and below does not specifically refer to the end capable of releasing low temperatures, but rather to a container or unit capable of providing and maintaining a corresponding constant temperature, containing an insulation layer to ensure temperature stability. These three cold ends provide different levels of refrigeration temperatures to achieve graded processing of the mixed refrigerant.

[0040] The first cold end 9 provides a pre-cooling temperature, which can be set and maintained stably at around 0°C to create a favorable low-temperature environment for the subsequent oil removal process. The second cold end 10 provides a first condensation temperature, lower than the pre-cooling temperature, for example, it can be set at -40°C, to condense the components with higher boiling points in the refrigerant mixture. The third cold end 11 provides a second condensation temperature, lower than the first condensation temperature, for example, it can be set at -60°C, to condense the components with lower boiling points in the refrigerant mixture. By setting these temperatures, the first condensation temperature (-40°C) is ensured to be higher than the second condensation temperature (-60°C), which is crucial for achieving staged condensation of the refrigerant according to its boiling point. The Stirling refrigerator 12 can control and maintain these three cold ends at the set target temperatures by adjusting the operating frequency of its internal pistons, etc.

[0041] The inlet of the electrostatic filter unit 6 is connected to the upstream pretreatment unit via a pipe. The outlet of the electrostatic filter unit 6 is connected to the inlet of the downstream first condenser 7. To improve oil removal efficiency, the electrostatic filter unit 6 is thermally coupled to the first cold end 9 of the Stirling refrigerator 12. When the Stirling refrigerator 12 is operating, the first cold end 9 continuously generates a low temperature of around 0°C or lower, which is transferred to the electrostatic filter unit 6, maintaining its operating temperature at the pre-cooling temperature. When the gaseous refrigerant mixture containing oil mist flows through the low-temperature electrostatic filter unit 6, the oil droplets increase in viscosity due to the decrease in temperature, making them more easily captured and aggregated under the action of the electrostatic field. Thus, the electrostatic filter unit 6 can perform high-precision oil removal treatment on the gaseous refrigerant mixture at the pre-cooling temperature.

[0042] The inlet of the first condenser 7 is connected to the outlet of the electrostatic filter unit 6 via a pipe, thereby receiving the gaseous refrigerant mixture after high-precision oil removal. The first condenser 7 is thermally coupled to the second cold end 10 of the Stirling refrigerator 12. Specifically, the second cold end 10 provides a stable low temperature for the first condenser 7, maintaining its operating temperature at the first condensation temperature (e.g., -40°C). When the gaseous refrigerant mixture flows through the first condenser 7, the components with relatively higher boiling points (i.e., high-boiling-point components) are condensed into liquids because they have reached their condensation points at that pressure. The components with relatively lower boiling points, however, remain gaseous because they have not reached their condensation points.

[0043] The inlet of the second condenser 8 is connected via a pipe to the gas outlet of the first condenser 7 to receive the gaseous mixture flowing out of the first condenser 7, which mainly contains low-boiling-point components. The second condenser 8 is thermally coupled to the third cold end 11 of the Stirling refrigerator 12. The third cold end 11 provides a lower temperature to the second condenser 8, maintaining its operating temperature at the second condensation temperature (e.g., -60°C). At this lower temperature, the remaining low-boiling-point components are effectively condensed into a liquid, thereby achieving separation from any small amount of non-condensable gases (such as air) that may be entrained in the refrigerant mixture. These non-condensable gases can be discharged through an exhaust valve V8 located on the second condenser 8.

[0044] To control the refrigerant flow path, several valves are installed on the system piping. For example, a main control valve V6 is installed on the connecting pipe between the electrostatic filter unit 6 and the first condenser 7. By opening the main control valve V6, qualified refrigerant gas after oil removal can enter the subsequent condensation and separation stage.

[0045] With the above structure, the system of this embodiment utilizes the multi-stage low temperature provided by the Stirling refrigerator 12 to first achieve efficient oil removal at the pre-cooling temperature in conjunction with the electrostatic filter unit 6. Then, it uses the progressively decreasing condensation temperature to perform staged condensation of the mixed refrigerant, thereby efficiently and accurately separating the mixed refrigerant into high-boiling-point components and low-boiling-point components, achieving efficient recovery and purification of the mixed refrigerant.

[0046] In one embodiment, the precooling temperature is higher than the first condensation temperature; the electrostatic filtration unit 6 includes an electrostatic generator and a dust collection plate, and an ionization zone is formed between the electrostatic generator and the dust collection plate.

[0047] like Figure 1 and Figure 2 As shown, in this embodiment, the pre-cooling temperature provided by the first cold end 9 is higher than the first condensation temperature provided by the second cold end 10. For example, the pre-cooling temperature is set to 0°C, and the first condensation temperature is set to -40°C. Pre-cooling the gaseous refrigerant at the relatively mild low temperature of 0°C aims to effectively reduce the temperature of the oil mist particles and increase their viscosity, making them easier to capture, without causing large-scale condensation of the refrigerant components. Subsequently, at the even lower temperature of -40°C, the de-oiled gaseous refrigerant is condensed to separate the high-boiling-point components. This design ensures that the two key steps of de-oiling and condensation are carried out within their respective optimal temperature ranges, avoiding mutual interference between processes and improving the overall system's processing efficiency and separation accuracy.

[0048] The electrostatic filtration unit 6 includes an electrostatic generator and a set of dust collection plates. The electrostatic generator is composed of high-voltage electrodes (such as discharge wires) used to generate a high-voltage electrostatic field. When the system is running, the electrostatic generator is energized, forming a strong electric field region, i.e., an ionization region, between itself and the dust collection plates. When a gaseous refrigerant mixture containing tiny oil mist particles flows through this ionization region, the oil mist particles are ionized and become charged. Driven by the electric field force, the charged oil mist particles migrate directionally and are adsorbed onto the surface of the dust collection plates with opposite charge polarity. Over time, the oil droplets adsorbed on the dust collection plates gradually gather, condense, and flow downwards due to gravity, eventually converging at the bottom of the electrostatic filtration unit 6 and periodically discharged into the second oil collection container 15 through the oil drain valve V5. In this way, the electrostatic filtration unit 6 can efficiently remove micron-sized or even submicron-sized oil droplets suspended in the gaseous refrigerant, achieving high-precision gas-oil separation.

[0049] In one embodiment, the system further includes a first recovery tank 21 connected to the liquid outlet of the first condenser 7; and a second recovery tank 22 connected to the liquid outlet of the second condenser 8.

[0050] like Figure 1 As shown, in this embodiment, the system further includes a first recovery tank 21 connected to the liquid outlet of the first condenser 7, and a second recovery tank 22 connected to the liquid outlet of the second condenser 8.

[0051] Specifically, the first recovery storage tank 21 is used to collect and store the high-boiling-point refrigerant components liquefied in the first condenser 7. During system operation, when the gaseous refrigerant mixture flows through the first condenser 7 operating at a first condensation temperature (e.g., -40°C), the condensed and liquefied high-boiling-point liquid components will collect at the bottom of the first condenser 7 due to gravity. A liquid outlet is provided at this bottom, which is connected to the inlet of the first recovery storage tank 21 via a connecting pipe. The liquefied refrigerant then flows into the first recovery storage tank 21 for storage. To ensure unidirectional liquid flow and prevent backflow of gas from the storage tank back into the condenser, thus affecting separation efficiency, a first check valve V9 is preferably installed on this connecting pipe.

[0052] Similarly, the second recovery tank 22 is used to collect and store the low-boiling-point refrigerant components liquefied in the second condenser 8. When the gas flowing out of the first condenser 7, which mainly contains low-boiling-point components, enters the second condenser 8, which operates at a second condensing temperature (e.g., -60°C), the low-boiling-point components are condensed into liquid and collect at the bottom of the second condenser 8. This bottom is also provided with a liquid outlet, which is connected to the inlet of the second recovery tank 22 via a connecting pipe. To prevent gas backflow, a second check valve V10 is installed on this connecting pipe.

[0053] By configuring these two independent recovery tanks, this system achieves the classified collection and storage of different single-component refrigerants after separation. The first recovery tank 21 collects high-purity, high-boiling-point refrigerant components, while the second recovery tank 22 collects high-purity, low-boiling-point refrigerant components. This design allows the two regenerated single-function refrigerants to be stored independently, facilitating subsequent separate metering, purity testing, and reuse. This completes the entire recovery and regeneration process from the purification and separation of the mixed refrigerant to the collection of the final product.

[0054] In one embodiment, the system further includes an adsorption tower 5 disposed upstream of the electrostatic filtration unit 6, wherein an adsorbent is disposed within the adsorption tower 5.

[0055] like Figure 1 As shown, in this embodiment, the system further includes an adsorption tower 5 disposed upstream of the electrostatic filtration unit 6. The inlet of the adsorption tower 5 is connected to the outlet of an upstream device (such as the compressor 4, which will be described later), and its outlet is connected to the inlet of the electrostatic filtration unit 6 via a connecting pipe. The interior of the adsorption tower 5 is filled with an adsorbent for adsorbing moisture and / or acidic substances in the gaseous mixed refrigerant.

[0056] The adsorbent is chosen to selectively adsorb trace impurities remaining in the gaseous refrigerant mixture, while having a weak adsorption capacity for the refrigerant molecules themselves. In this embodiment, the adsorbent can be zeolite molecular sieves, activated alumina, silica gel, or any combination thereof. For example, molecular sieves with specific pore sizes can efficiently adsorb water molecules, while activated alumina is effective in removing acidic substances that may be generated during refrigerant degradation.

[0057] In the system's workflow, the gaseous mixed refrigerant from upstream flows through the adsorption tower 5 before entering the electrostatic filtration unit 6 for deep oil removal. As the gas passes through the adsorbent bed inside the adsorption tower 5, water molecules and acidic substances are captured and retained by the microporous structure of the adsorbent surface, while refrigerant molecules can pass through smoothly. Thus, after treatment in the adsorption tower 5, the moisture and acidic substances in the gaseous mixed refrigerant are effectively removed, thereby improving its overall purity.

[0058] By adding this adsorption tower 5, the system can pre-remove moisture and acidic impurities before entering the low-temperature oil removal and separation process. This design avoids potential ice blockage or corrosion problems caused by these impurities in subsequent low-temperature environments (such as -40℃ to -60℃), ensuring stable system operation and equipment lifespan; at the same time, it also ensures that the finally separated and recovered refrigerant product has higher purity, meeting the standards for regeneration. To control the refrigerant flow, an adsorption tower inlet valve V3 can be installed on the inlet pipe of adsorption tower 5 to control whether gaseous refrigerant can enter adsorption tower 5.

[0059] In one embodiment, the system further includes a compressor 4 disposed upstream of the adsorption tower 5 and a distillation tank 2 disposed upstream of the compressor 4; the distillation tank 2 is provided with a heat exchange pipe; the inlet of the compressor 4 is connected to the gas outlet of the distillation tank 2, the outlet of the compressor 4 is connected to the inlet of the heat exchange pipe, and the outlet of the heat exchange pipe is connected to the inlet of the adsorption tower 5.

[0060] like Figure 1 As shown, in this embodiment, the system further includes a compressor 4 upstream of the adsorption tower 5; and upstream of the compressor 4, a distillation tank 2 is also included. These components together constitute an oil separation and energy self-circulation unit.

[0061] Specifically, the distillation tank 2 is the inlet of the entire recycling and purification process, used to receive the mixed refrigerant to be treated, containing impurities such as lubricating oil, extracted from the external refrigeration equipment 1. Figure 1 As shown, an inlet valve V1 is installed on the connecting pipeline between the external refrigeration unit 1 and the distillation tank 2 to control the introduction of the refrigerant to be treated, serving as the starting control point for the entire purification process. The function of the distillation tank 2 is to utilize the significant boiling point difference between the refrigerant and lubricating oil to perform preliminary gas-liquid separation and oil removal. To achieve efficient energy utilization, a heat exchange pipe (not separately labeled) is installed inside the distillation tank 2.

[0062] The compressor 4 is selected as an oil-free compressor to avoid secondary oil contamination of the refrigerant during processing. Its location and connection method are as follows: the inlet of the compressor 4 is connected to the gas outlet at the top of the distillation tank 2 via a connecting pipe. This connection method allows the compressor 4 to extract the gaseous refrigerant formed in the distillation tank 2 due to pressure reduction or heating.

[0063] A key design feature of this embodiment lies in the internal recycling of energy. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 4 is not directly sent to the adsorption tower 5, but is instead connected via another connecting pipe to the inlet of the heat exchange pipe located inside the distillation tank 2. Simultaneously, the outlet of this heat exchange pipe is then connected to the inlet of the adsorption tower 5 via a pipe (via the adsorption tower inlet valve V3).

[0064] The workflow of this structure is as follows:

[0065] Vacuuming and Evaporation: After compressor 4 starts, it continuously draws gaseous refrigerant from the upper space of distillation tank 2, causing a decrease in the pressure inside the tank. The decrease in pressure promotes the "flash evaporation" of the liquid refrigerant inside the tank at room temperature, that is, rapid vaporization, thereby separating it from the high-boiling-point liquid lubricating oil. The separated lubricating oil settles at the bottom of the tank and can be discharged to the first oil collection container 3 through the oil drain valve V2 at the bottom of the tank.

[0066] Compression and Heating: The extracted gaseous refrigerant is compressed by compressor 4, and its pressure and temperature increase, forming a high-temperature and high-pressure gaseous refrigerant.

[0067] Heat exchange and energy recovery: The high-temperature, high-pressure gas enters the heat exchange pipe inside the distillation tank 2. As it flows through the pipe, it transfers a large amount of heat of compression it carries to the cooler liquid refrigerant outside the pipe via the pipe wall. This process achieves a dual effect: on the one hand, the liquid refrigerant inside the tank gains heat, allowing the evaporation process to continue efficiently, providing a continuous gas supply for the compressor 4; on the other hand, the gaseous refrigerant itself cools down after heat exchange due to the release of heat, but still maintains a high pressure.

[0068] Downstream: The high-pressure gaseous refrigerant, cooled by heat exchange, flows out from the outlet of the heat exchange pipe and then enters the downstream adsorption tower 5 for dehydration and deacidification. The lower temperature results in higher adsorption efficiency in the subsequent adsorption tower 5.

[0069] With the above configuration, this system utilizes the waste heat (compression heat) generated during the compression process as the heat source for the distillation process, eliminating the need for additional heating devices, significantly reducing the system's operating energy consumption, and optimizing the thermodynamic conditions of the entire purification process.

[0070] In one embodiment, the system further includes a purity detection device 20 disposed between the electrostatic filtration unit 6 and the first condenser 7; a circulation pipeline 24, the inlet end of which is connected to the purity detection device 20 and the outlet end of which is connected to the inlet of the compressor 4; and a control valve disposed in the circulation pipeline 24.

[0071] like Figure 1 As shown, in this embodiment, the system also includes a purity detection device 20 disposed between the electrostatic filtration unit 6 and the first condenser 7. Furthermore, the system is equipped with a circulation pipeline 24 and a control valve, namely the circulation pipeline control valve V7, disposed on the circulation pipeline 24.

[0072] Specifically, the purity detection device 20 is installed in series on the main pipeline between the outlet of the electrostatic filter unit 6 and the inlet of the first condenser 7. This purity detection device 20 is used to monitor the purity of the gaseous mixed refrigerant flowing through this pipeline, which has undergone oil, water, and acid removal treatment. Here, "purity" is a comprehensive indicator, primarily measuring whether the content of residual contaminants (such as oil, water, and acid) in the refrigerant is below a preset standard value. The purity detection device 20 can be an infrared gas analyzer, a gas chromatograph, or other sensors suitable for online detection of specific contaminant content. Its detection results are fed back to the system's central control unit (not shown) in real time.

[0073] The circulation pipeline 24 is designed to initiate a re-purification process when the refrigerant purity is substandard. Figure 1 As shown, the inlet connection point of the circulation pipeline 24 is located downstream of the purity detection device 20 and upstream of the main control valve V6. Its outlet is connected back to the inlet of the compressor 4 via a pipeline.

[0074] The circulation pipeline control valve V7 is installed on the circulation pipeline 24 and is used to control the opening and closing of the circulation pipeline 24.

[0075] The system's working logic is as follows:

[0076] Normal purification process: When the system is operating stably and the refrigerant contamination level is not high, the refrigerant purity detected by the purity detection device 20 meets the preset standard. At this time, the central control unit will instruct the main control valve V6 to remain open, and simultaneously instruct the circulation pipeline control valve V7 to remain closed. Qualified gaseous refrigerant will smoothly pass through the main pipeline into the downstream first condenser 7 and second condenser 8 for component separation.

[0077] Circulating purification process: When the system is first started, or when the refrigerant being processed is severely contaminated, the purity detection device 20 may detect that the purity of the gaseous refrigerant does not meet the preset standard. In this case, the central control unit will immediately change the valve status: close the main control valve V6 to prevent unqualified gas from entering the subsequent separation units (first condenser 7 and second condenser 8); at the same time, open the circulation pipeline control valve V7 to establish a circulation loop. At this time, the unqualified gaseous refrigerant will be diverted through the circulation pipeline 24 and returned to the inlet of the compressor 4. At the inlet of the compressor 4, this recirculated gas will mix with the gas newly evaporated from the distillation tank 2, and then undergo a series of purification steps such as compression, heat exchange, impurity removal by the adsorption tower 5, and oil removal by the electrostatic filtration unit 6.

[0078] This closed-loop purification process continues until the purity detection device 20 detects that the refrigerant purity in the pipeline reaches the preset standard. Once the purity is qualified, the control system will switch the valve status again, closing the circulation pipeline control valve V7 and opening the main pipeline control valve V6, so that the system returns to the normal continuous purification and separation process.

[0079] By adding the purity detection device 20, the circulation pipeline 24, and the corresponding control logic, this system forms a closed-loop quality control system. It can perform centralized and intensive purification treatment on specific batches of refrigerant, ensuring that only fully purified, high-purity refrigerant can enter the final separation stage, thereby effectively guaranteeing the quality of the recovered products and improving the stability and reliability of the system.

[0080] In one embodiment, a heat recovery loop is further provided between the hot end of the Stirling refrigerator 12 and the adsorption tower 5, the heat recovery loop being configured to transfer waste heat from the hot end of the Stirling refrigerator 12 to the adsorption tower 5.

[0081] like Figure 1 As shown, in this embodiment, the system further includes a heat recovery loop disposed between the hot end of the Stirling refrigerator 12 and the adsorption tower 5. This heat recovery loop is configured to transfer waste heat from the hot end of the Stirling refrigerator 12 to the adsorption tower 5 for heating and regenerating the adsorbent within the adsorption tower 5.

[0082] Specifically, the Stirling refrigerator 12 operates according to the reverse Stirling cycle principle. While its cold ends (i.e., the first cold end 9, the second cold end 10, and the third cold end 11) output cooling capacity, its hot ends continuously generate a large amount of heat. In traditional refrigeration applications, this heat is usually discharged directly into the environment as waste heat, resulting in energy waste.

[0083] This embodiment utilizes the inevitable byproduct—waste heat. A heat recovery loop is constructed to connect the hot end of the Stirling refrigerator 12 to the adsorption tower 5. The core function of this loop is as a heat transfer system.

[0084] When the adsorbent in adsorption tower 5 needs regeneration, the system initiates the regeneration process. At this time, the heat recovery loop starts working, collecting the heat energy generated by the hot end of the Stirling refrigerator 12 and transferring it to adsorption tower 5. After the heat is transferred to adsorption tower 5, it heats the saturated adsorbent inside. Under high temperature, water molecules and acidic molecules previously trapped in the micropores of the adsorbent gain sufficient energy to desorb and revert to a gaseous state, thus restoring the adsorption capacity of the adsorbent.

[0085] By adding this heat recovery loop, the system converts the waste heat inevitably generated during the refrigeration process of the Stirling refrigerator 12 into valuable energy required for the adsorbent regeneration process. This design not only avoids the need for additional energy-consuming equipment such as electric heaters for the regeneration process of the adsorption tower 5, reducing the total energy consumption and operating costs of the entire system, but also embodies the energy-saving and environmentally friendly design concept of energy cascade utilization, resulting in a significant improvement in the overall energy efficiency of the system.

[0086] In one embodiment, the adsorption tower 5 includes a first housing 27 for containing the adsorbent and a second housing 28 covering the outside of the first housing 27, with a flow chamber 29 formed between the first housing 27 and the second housing 28; the heat recovery circuit includes a circulation pump 16, a heat transfer medium, and a heat exchanger 14 thermally coupled to the hot end of the Stirling refrigerator 12, the circulation pump 16 being configured to drive the heat transfer medium to circulate between the heat exchanger 14 and the flow chamber 29.

[0087] like Figure 2 As shown, in this embodiment, the adsorption tower 5 includes a first shell 27 (i.e., inner liner) for containing the adsorbent, and a second shell 28 (i.e., outer shell) covering the outside of the first shell 27. A closed, annular flow chamber 29, i.e., a heating jacket, is naturally formed between the first shell 27 and the second shell 28. This double-shell design aims to achieve uniform and indirect heating of the adsorbent within the adsorption tower 5.

[0088] Accordingly, the heat recovery loop is designed as a closed liquid circulation system, the specific components of which are as follows:

[0089] Heat exchanger 14: This heat exchanger 14 is thermally coupled to the hot end of the Stirling refrigerator 12. Specifically, the coil of the heat exchanger 14 can be directly wound around the heat dissipation component of the hot end of the Stirling refrigerator 12, or it can share a heat storage material 13 with the hot end of the Stirling refrigerator 12. Its function is to absorb the waste heat generated by the Stirling refrigerator 12 and transfer the heat to the heat transfer medium in the loop.

[0090] Heat transfer medium: The liquid that circulates in the pipes and equipment throughout the heat recovery loop.

[0091] Circulation pump 16: The circulation pump 16 is connected in series in the pipeline of the heat recovery circuit as a power source to drive the circulation of the heat transfer medium.

[0092] These components are connected by pipes, forming a complete closed loop. The circulating pump 16 is configured to drive the heat transfer medium to circulate continuously between the heat exchanger 14 and the flow chamber 29 of the adsorption tower 5.

[0093] A complete adsorbent regeneration heating cycle is as follows:

[0094] Heat absorption process: The circulating pump 16 starts, driving the heat transfer medium at room temperature / low temperature to flow through the heat exchanger 14. In the heat exchanger 14, the heat transfer medium absorbs waste heat from the hot end of the Stirling refrigerator 12, and its own temperature rises.

[0095] Transportation process: The high-temperature heat transfer medium carrying a large amount of heat energy is pumped along the pipeline to the inlet of the flow chamber 29 of the adsorption tower 5 under the drive of the circulating pump 16.

[0096] Exothermic process: The high-temperature heat transfer medium flows within the flow chamber 29 of the adsorption tower 5. During this flow, it transfers heat to the adsorbent inside the first shell 27, thus heating the adsorbent. Simultaneously, the temperature of the heat transfer medium itself decreases due to the release of heat.

[0097] Reflux process: The cooled heat transfer medium flows out from the outlet of the flow chamber 29 and is pumped back to the inlet of the heat exchanger 14 by the circulation pump 16 to absorb new heat and complete a cycle.

[0098] Through the aforementioned double-shell design of the adsorption tower 5 and the loop design including the circulating pump 16 and the heat transfer medium, this embodiment constructs a stable, controllable, and efficient indirect heating system. It not only ensures that heat can be reliably transferred from the hot end of the Stirling refrigerator 12 to the adsorption tower 5, but also guarantees the safety and cleanliness of the heating process, effectively preventing any potential contamination of the adsorbent. To control the start and stop of the regeneration process, a heat recovery loop control valve V11 can be installed on the pipeline connecting the circulating pump 16 and the adsorption tower 5.

[0099] In a specific example, the hot end of the Stirling refrigerator 12 can be coupled to a heat storage material 13 for temporary storage and stabilization of heat output. The heat recovery loop then extracts heat from the heat storage material 13 and delivers it to the adsorption tower 5.

[0100] In this embodiment, to more flexibly control the adsorbent regeneration process, a heat recovery loop control valve V11 is also provided in the heat recovery loop. This valve is specifically installed on the pipeline between the circulating pump 16 and the flow chamber 29 of the adsorption tower 5, and is used to control whether the heat transfer medium enters the flow chamber 29 of the adsorption tower 5. When adsorbent regeneration is required, the central control unit of the system issues a command to open the heat recovery loop control valve V11, allowing the heat transfer medium, heated by the heat exchanger 14, to enter the flow chamber 29 of the adsorption tower 5 to heat the adsorbent. Under non-regeneration conditions, the heat recovery loop control valve V11 is closed, cutting off the circulation path of the heat transfer medium, thereby avoiding overheating of the adsorption tower 5 or unnecessary energy consumption. Through the opening and closing control of the heat recovery loop control valve V11, the system can regulate the start and stop of the adsorbent regeneration process, improving the safety and controllability of the entire heat recovery loop operation.

[0101] In one embodiment, the system further includes a vacuum pump 23 connected to the adsorption tower 5, the vacuum pump 23 being configured to evacuate the adsorption tower 5 while the adsorbent is heated in the heat recovery loop.

[0102] like Figure 1 As shown, in this embodiment, the system also includes a vacuum pump 23 connected to the adsorption tower 5. The vacuum pump 23 is connected to the internal space of the first shell 27 (i.e., the inner liner containing the adsorbent) of the adsorption tower 5 via pipelines and a vacuum pipeline control valve V4.

[0103] The vacuum pump 23 is configured to simultaneously heat the adsorbent in the heat recovery circuit and evacuate the interior of the adsorption tower 5. This coordinated heating and vacuuming process constitutes the "vacuum thermal regeneration" process, whose workflow and advantages are as follows:

[0104] When the adsorbent regeneration process is started, the system performs two operations simultaneously:

[0105] Heating: As mentioned above, the heat recovery loop is started to transfer the waste heat of the Stirling refrigerator 12 to the adsorption tower 5 to heat the saturated adsorbent inside.

[0106] Vacuuming: At the same time, open the vacuum pipeline control valve V4 and start the vacuum pump 23 to continuously extract the gas from the inner liner of the adsorption tower 5 and discharge it from the system.

[0107] These two operations work together to produce a synergistic effect:

[0108] First, under vacuum (negative pressure) conditions, the boiling point of substances and the temperature required for desorption are both lowered. This means that adsorbed water and acidic substances can be desorbed from the adsorbent surface at a relatively lower heating temperature. This not only saves the energy required for heating but also helps protect the microporous structure of the adsorbent, preventing performance degradation due to prolonged high temperatures and thus extending the adsorbent's lifespan.

[0109] Secondly, the continuous pumping action of vacuum pump 23 will continuously and forcibly extract gaseous impurities (such as water vapor, acidic gases, etc.) desorbed from the surface of the adsorbent from the adsorption tower 5. This promotes the continuous and unidirectional desorption process towards complete desorption. Compared with simple heating, this method greatly improves the efficiency and depth of regeneration, ensuring that the activity of the adsorbent can be restored to the greatest extent.

[0110] In summary, by combining the heating regeneration of the heat recovery circuit with the vacuum regeneration of the vacuum pump 23, this embodiment constructs a highly efficient and thorough adsorbent regeneration system.

[0111] like Figure 3 As shown, corresponding to the above-mentioned mixed refrigerant recovery and purification system, this embodiment of the invention also provides a mixed refrigerant recovery and purification method, characterized by including the following steps S100-S500:

[0112] S100. Introduce the gaseous mixed refrigerant into the pretreatment unit to remove moisture and acidic substances from the gaseous mixed refrigerant;

[0113] First, the mixed refrigerant, which is in liquid or gas-liquid mixture and contains impurities such as lubricating oil, moisture, and acidic substances, extracted from the waste refrigeration equipment 1, is introduced into the pretreatment unit. In this embodiment, the pretreatment process includes preliminary oil removal, vaporization, water removal, and acid removal. Specifically, the refrigerant to be treated first enters the distillation tank 2. Utilizing the boiling point difference between the refrigerant and lubricating oil, the refrigerant flashes vaporized in the tank under the suction action of the compressor 4, while most of the lubricating oil remains in liquid form and collects at the bottom of the tank, and is discharged through valve V2. The vaporized refrigerant is compressed into a high-temperature, high-pressure gas by the compressor 4, and flows through the heat exchange pipes set in the distillation tank 2. It uses its own heat of compression to provide the energy required for the evaporation of the liquid in the tank, realizing energy self-circulation. The cooled, high-pressure gaseous refrigerant then enters the adsorption tower 5, where the moisture and acidic substances are efficiently adsorbed and removed by the adsorbents such as molecular sieves and activated alumina filled in the tower.

[0114] S200. Using the first cold end 9 of the Stirling refrigerator 12, the electrostatic filter unit 6 is cooled to a pre-cooling temperature, and the gaseous mixed refrigerant is de-oiled through the electrostatic filter unit 6 at the pre-cooling temperature.

[0115] At the start of the purification process or during its continuous operation, the Stirling refrigerator 12 operates, with its first cold end 9 generating and maintaining a pre-cooling temperature (e.g., 0°C). This low temperature, achieved through thermal coupling, cools the electrostatic filtration unit 6 to this pre-cooling temperature. After the aforementioned pretreatment steps, the gaseous refrigerant mixture, now free of moisture and acidic substances, flows from the adsorption tower 5 into the cooled electrostatic filtration unit 6. At this pre-cooling temperature, the viscosity of residual fine oil mist particles in the refrigerant increases, making them more easily ionized, captured, and aggregated under the influence of an electrostatic field. This step achieves high-precision removal of trace amounts of lubricating oil from the refrigerant.

[0116] S300, The degreased gaseous mixed refrigerant is introduced into the first condenser 7, and the high-boiling-point components in the gaseous mixed refrigerant are condensed at the first condensation temperature provided by the second cold end 10 of the Stirling refrigerator 12.

[0117] The gaseous refrigerant mixture, after undergoing high-precision oil removal, is introduced into the first condenser 7 connected in series downstream. Simultaneously, the second cold end 10 of the Stirling refrigerator 12 provides the first condenser 7 with a stable first condensation temperature (e.g., -40°C), which is higher than the subsequent second condensation temperature. At this temperature, the components with relatively high boiling points in the gaseous refrigerant mixture (i.e., high-boiling-point components) reach their condensation points and are condensed into liquids.

[0118] S400, The uncondensed gaseous mixed refrigerant is introduced into the second condenser 8, and the low-boiling-point components in the gaseous mixed refrigerant are condensed at the second condensation temperature provided by the third cold end 11 of the Stirling refrigerator 12.

[0119] The uncondensed gas in the first condenser 7, mainly composed of components with relatively low boiling points, flows out from the gas outlet of the first condenser 7 and is directly introduced into the second condenser 8. The third cold end 11 of the Stirling refrigerator 12 provides the second condenser 8 with a lower, stable second condensation temperature (e.g., -60°C). At this lower temperature, these low-boiling-point components reach their condensation point and are also condensed into liquid. The very small amount of non-condensable gases (such as air) that may be entrained in the mixed refrigerant, because their boiling points are much lower than -60°C, will remain in a gaseous state in this step, thus achieving effective separation from the refrigerant components and can be discharged through the exhaust valve V8.

[0120] S500: The refrigerant components obtained by condensation in the first condenser 7 and the second condenser 8 are collected into the corresponding recovery storage tanks.

[0121] Finally, the two liquid refrigerant components obtained through the aforementioned staged condensation process are collected separately. Specifically, the high-boiling-point liquid component obtained by condensation in the first condenser 7 flows into the first recovery storage tank 21 for storage through its bottom liquid outlet and the first check valve V9. The low-boiling-point liquid component obtained by condensation in the second condenser 8 flows into the second recovery storage tank 22 for storage through its bottom liquid outlet and the second check valve V10. This completes the efficient purification, separation, and final product collection of the mixed refrigerant.

[0122] In this embodiment, when starting the normal separation and purification process, the inlet valve V1, adsorption tower inlet valve V3, main control valve V6, and exhaust valve V8 need to be opened; at the same time, the circulation pipeline control valve V7, vacuum pipeline control valve V4, and heat recovery loop control valve V11 should be closed. The first check valve V9 and the second check valve V10 are one-way valves, which automatically open with the fluid pressure in this process and do not require external control.

[0123] After the process starts, the mixed refrigerant to be treated enters the distillation tank 2 via V1 for preliminary gas-liquid separation. The gaseous refrigerant is drawn by the compressor 4, and after heat exchange, it enters the adsorption tower 5 via V3 for dehydration and acid removal. Subsequently, the gas enters the electrostatic filtration unit 6 for deep oil removal. The treated gas flows through the purity detection device 20, and after confirming that the purity meets the standard, it enters the subsequent condensation and separation stage via the opened V6. The high-boiling-point component is liquefied in the first condenser 7 and collected in the first recovery storage tank 21 via V9; the low-boiling-point component is liquefied in the second condenser 8 and collected in the second recovery storage tank 22 via V10. Non-condensable gases are discharged from the system via the opened V8.

[0124] During the operation of this process, the drain valves V2 and V5 can be opened intermittently according to the liquid level monitoring to drain the lubricating oil accumulated at the bottom of the distillation tank 2 and the electrostatic filter unit 6 into the first oil collection container 3 and the second oil collection container 15, respectively.

[0125] In this embodiment, when the system is initially started up or when processing heavily contaminated refrigerant, the purity detection device 20 may detect that the refrigerant purity is substandard. At this time, the system will automatically switch to a circulating purification process to reprocess the substandard refrigerant until its purity meets the standard.

[0126] The process is triggered when the purity fails to meet the standard. At this point, the central control unit immediately changes the valve status: closing the main control valve V6 to prevent substandard gas from entering the subsequent condensation unit; and simultaneously opening the circulation pipeline control valve V7. Other valves (such as V1 and V3) remain in their original states to ensure continuous material input and pretreatment.

[0127] In this mode, substandard gaseous refrigerant, after flowing out of the purity detection device 20, cannot pass through the closed V6. Instead, it is guided through the open V7 into the circulation pipeline 24, returning to the inlet of the compressor 4. Here, it mixes with the gas newly entering from the distillation tank 2 and undergoes a series of purification steps, including compression, heat exchange, impurity removal by the adsorption tower 5, and oil removal by the electrostatic filtration unit 6. This closed-loop cycle continues until the purity detection device 20 confirms that the gas purity reaches the preset standard. At this point, the system automatically closes V7 and reopens V6, resuming the normal continuous separation and purification process.

[0128] In this embodiment, when the adsorbent in the adsorption tower 5 becomes ineffective due to adsorption saturation, a regeneration process needs to be initiated to heat and regenerate it in order to restore its adsorption capacity.

[0129] Before starting the regeneration process, the normal purification process should be stopped and all valves related to the main flow path should be closed, including V1, V3, V6, etc.

[0130] Subsequently, the heat recovery loop control valve V11 and the vacuum pipeline control valve V4 are opened. Upon opening V11, the circulation pump 16 starts, pumping the heat transfer medium heated by the hot end of the Stirling refrigerator 12 into the flow chamber of the adsorption tower 5, uniformly heating the saturated adsorbent inside. Simultaneously, V4 is opened and the vacuum pump 23 is started, continuously evacuating the interior of the adsorption tower 5. Under the synergistic effect of heating and evacuation, the previously adsorbed moisture and acidic substances desorb in gaseous form and are extracted from the system by the vacuum pump 23, thus achieving efficient and thorough regeneration of the adsorbent. After regeneration is complete, V4 and V11 are closed, and the adsorption tower 5 can be put back into use after cooling.

[0131] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A mixed refrigerant recovery and purification system, characterized in that, include: A Stirling refrigerator, the Stirling refrigerator having a first cold end providing a pre-cooling temperature, a second cold end providing a first condensing temperature, and a third cold end providing a second condensing temperature, wherein the first condensing temperature is higher than the second condensing temperature; An electrostatic filtration unit, which is thermally coupled to the first cold end, is used to remove oil from the gaseous mixed refrigerant at the pre-cooling temperature; A first condenser is located downstream of the electrostatic filter unit and is thermally coupled to the second cold end. The first condenser is used to condense the high-boiling-point components in the gaseous mixed refrigerant at the first condensation temperature. and The second condenser is located downstream of the first condenser and is thermally coupled to the third cold end. The second condenser is used to condense the low-boiling-point components in the gaseous mixed refrigerant at the second condensation temperature.

2. The system according to claim 1, characterized in that, The precooling temperature is higher than the first condensation temperature; the electrostatic filtration unit includes an electrostatic generator and a dust collection plate, and an ionization zone is formed between the electrostatic generator and the dust collection plate.

3. The system according to claim 1, characterized in that, It also includes a first recovery tank connected to the liquid outlet of the first condenser; and a second recovery tank connected to the liquid outlet of the second condenser.

4. The system according to claim 1, characterized in that, It also includes an adsorption tower located upstream of the electrostatic filtration unit, wherein an adsorbent is disposed in the adsorption tower.

5. The system according to claim 4, characterized in that, It also includes a compressor located upstream of the adsorption tower and a distillation tank located upstream of the compressor; the distillation tank is provided with a heat exchange pipe; the inlet of the compressor is connected to the gas outlet of the distillation tank, the outlet of the compressor is connected to the inlet of the heat exchange pipe, and the outlet of the heat exchange pipe is connected to the inlet of the adsorption tower.

6. The system according to claim 5, characterized in that, It also includes a purity detection device disposed between the electrostatic filtration unit and the first condenser; a circulation pipeline, the inlet end of which is connected to the purity detection device and the outlet end of which is connected to the inlet of the compressor; and a control valve disposed in the circulation pipeline.

7. The system according to claim 4, characterized in that, It also includes a heat recovery loop disposed between the hot end of the Stirling refrigerator and the adsorption tower, the heat recovery loop being configured to transfer waste heat from the hot end of the Stirling refrigerator to the adsorption tower.

8. The system according to claim 7, characterized in that, The adsorption tower includes a first shell for containing the adsorbent and a second shell covering the outside of the first shell, with a flow chamber formed between the first shell and the second shell; the heat recovery circuit includes a circulating pump, a heat transfer medium and a heat exchanger thermally coupled to the hot end of the Stirling refrigerator, the circulating pump being configured to drive the heat transfer medium to circulate between the heat exchanger and the flow chamber.

9. The system according to claim 8, characterized in that, It also includes a vacuum pump connected to the adsorption tower, the vacuum pump being configured to evacuate the adsorption tower while the adsorbent is heated in the heat recovery loop.

10. A method for recovering and purifying a mixed refrigerant, characterized in that, Includes the following steps: The gaseous mixed refrigerant is introduced into the pretreatment unit to remove moisture and acidic substances from the gaseous mixed refrigerant; Using the first cold end of the Stirling refrigerator, the electrostatic filter unit is cooled to a pre-cooling temperature, and the gaseous mixed refrigerant is degreased by passing through the electrostatic filter unit at the pre-cooling temperature. The degreased gaseous refrigerant mixture is introduced into the first condenser, where the high-boiling-point components in the gaseous refrigerant mixture are condensed at the first condensation temperature provided by the second cold end of the Stirling refrigerator. Uncondensed gaseous refrigerant mixture is introduced into a second condenser, where the low-boiling-point components of the gaseous refrigerant mixture are condensed at a second condensation temperature provided by the third cold end of the Stirling refrigerator. The refrigerant components obtained by condensation in the first condenser and the second condenser are collected into the corresponding recovery storage tanks.

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