Apparatus and method for preparing non-azeotropic mixed refrigerant

Abstract

The application discloses a device and method for preparing non-azeotropic mixed refrigerant, which is used for preparing mixed refrigerant containing refrigerants with great difference in boiling point, and comprises high-low temperature liquid storage tanks, high-low temperature refrigerant pumps, heat regenerators, heat pump units, heating coolers, mixers and blending tanks and the like. The application realizes the same or similar mixing temperature of high-low temperature refrigerants before mixing through the heat regenerative effect of the heat regenerator and the compensation of the heat pump unit cooperating with the heating cooler, and ensures that the mixing temperature is less than the corresponding saturation temperature of the low-boiling-point refrigerant under the mixing pressure, so that the liquid phase and the liquid phase can be mixed in the mixer. The problems of long gas-liquid two-phase mixing time, complex equipment and easy generation of heat of solution and the like faced by the mixing of refrigerants with great difference in boiling point are solved, and the efficient, rapid and accurate preparation of the non-azeotropic mixed refrigerant is realized.

Description

Technical Field

[0001] This invention belongs to the field of refrigerant technology, and more specifically, relates to an apparatus and method for preparing a non-azeotropic refrigerant mixture. Background Technology

[0002] Mixed refrigerants represent an ideal approach for researching next-generation environmentally friendly and energy-saving refrigerants. Among these, non-azeotropic mixed refrigerants show considerable promise in reducing irreversible heat transfer losses in heat exchangers during thermodynamic cycles. For the production of non-azeotropic mixed refrigerants, the liquids of two refrigerants with similar boiling points, such as R32 and R125, or R1270 and R600a, can be directly mixed at room temperature. However, for refrigerants with significantly different boiling points, especially those where one refrigerant is already supercritical at room temperature, the production of mixed refrigerants faces key challenges such as long gas-liquid two-phase mixing times, complex equipment, and the generation of heat of solution. Furthermore, with increasing international demands for the thermodynamic and environmental performance of next-generation refrigerants, finding a method for the efficient, accurate, and stable preparation of non-azeotropic mixed refrigerants is urgently needed. Summary of the Invention

[0003] In order to solve the above-mentioned technical problems, the purpose of this invention is to provide an apparatus and method for preparing a non-azeotropic mixed refrigerant.

[0004] To achieve the above objectives, the present invention first provides an apparatus for preparing a non-azeotropic refrigerant mixture, comprising a high-boiling-point working fluid storage tank, a low-boiling-point working fluid storage tank, a high-boiling-point working fluid pump, a low-boiling-point working fluid pump, a heat pump unit, a heater / cooler, a regenerator, a pressure gauge, a thermometer, a flow meter, a mixer, a blending tank, a high-temperature measuring pipeline of the regenerator, a low-temperature side pipeline of the regenerator, a high-boiling-point working fluid pipeline, a low-boiling-point working fluid pipeline, and a refrigerant pipeline; the apparatus is divided into a high-boiling-point working fluid pipeline and a low-boiling-point working fluid pipeline before the high and low-temperature working fluids enter the mixer. The high-boiling-point working fluid pipeline is sequentially connected to the high-boiling-point storage tank, the high-boiling-point working fluid pump, the heater / cooler, the high-temperature side pipeline of the regenerator, and the flow meter; the low-boiling-point working fluid pipeline is sequentially connected to the low-boiling-point storage tank, the low-boiling-point working fluid pump, the low-temperature side pipeline of the regenerator, and the flow meter.

[0005] In the high-boiling-point working fluid pipeline, the outlet of the high-boiling-point storage tank is connected to the inlet of the high-boiling-point working fluid pump; the outlet of the high-boiling-point working fluid pump is connected to the inlet of the heater / cooler; the outlet of the heater / cooler is connected to the inlet of the high-temperature side pipeline of the regenerator; the outlet of the high-temperature measuring pipeline of the regenerator is connected to the inlet of the flow meter; and the outlet of the flow meter is connected to the inlet of the mixer. In the low-boiling-point working fluid pipeline, the outlet of the low-boiling-point storage tank is connected to the inlet of the low-boiling-point working fluid pump; the outlet of the low-boiling-point working fluid pump is connected to the inlet of the low-temperature side pipeline of the regenerator; the outlet of the low-temperature side pipeline of the regenerator is connected to the inlet of the flow meter; and the outlet of the flow meter is connected to the inlet of the mixer. The outlet of the mixer is connected to the inlet of the blending tank. The heater / cooler is connected to the heat pump unit via a refrigerant pipeline.

[0006] The high-boiling-point working fluid storage tank is located at ambient temperature and is used to store high-boiling-point working fluids. The ambient temperature is -5 to 30°C. At least one high-boiling-point working fluid is present, with a boiling point not lower than -60°C and a critical temperature higher than the ambient temperature. The low-boiling-point storage tank is a vacuum-insulated tank used to store low-boiling-point working fluids. At least one low-boiling-point working fluid is present, with a boiling point at least 30°C lower than the boiling point of the high-boiling-point working fluid. The high-boiling-point working fluid pump is used to adjust the pressure of the high-boiling-point working fluid to a mixing pressure, and the low-boiling-point working fluid pump is used to adjust the pressure of the low-boiling-point working fluid to a mixing pressure.

[0007] According to one embodiment of the present invention, the boiling point of the low-boiling-point refrigerant is 41-122°C lower than the boiling point of the high-boiling-point refrigerant.

[0008] According to one embodiment of the present invention, the pressure gauge, thermometer, and flow meter are used to measure or monitor the physical state of the high-boiling-point working fluid and the low-boiling-point working fluid, and the regenerator is a counter-flow or cross-flow heat exchanger used to reheat the high-boiling-point working fluid and the low-boiling-point working fluid.

[0009] According to one embodiment of the present invention, the heat pump unit and the heater / cooler are connected through a refrigerant pipeline to form a circuit for transferring heat or cold, which is used to compensate for the heat exchange between the high- and low-temperature working fluids so that the high-boiling-point working fluid and the low-boiling-point working fluid reach the same temperature before mixing.

[0010] According to one embodiment of the present invention, the heating and cooling device is a combined heating and cooling heat exchanger; when the refrigerant in the refrigerant pipeline does not have a sufficiently low freezing point, in order to prevent the refrigerant from freezing, the combined heating and cooling heat exchanger is installed in the high boiling point working fluid pipeline.

[0011] According to one embodiment of the present invention, the heating and cooling system is provided with two heat exchangers: a heater and a cooler. The heater is provided in the low-boiling-point working fluid pipeline, and the cooler is provided in the high-boiling-point working fluid pipeline. When the refrigerant in the refrigerant pipeline does not have a sufficiently low freezing point, in order to prevent the refrigerant from freezing, both the heater and the cooler are provided in the high-boiling-point working fluid pipeline.

[0012] According to one embodiment of the invention, the mixer is connected to a mixing tank to ensure thorough mixing of the refrigerant while shortening the mixing time.

[0013] According to another aspect of the present invention, the present invention also provides a method for preparing a non-azeotropic refrigerant mixture using the above-described apparatus, comprising the following steps:

[0014] S1: The high-boiling-point working fluid enters the high-boiling-point working fluid pipeline from the high-temperature storage tank. It is first pressurized to the specified mixing pressure by the high-boiling-point working fluid pump, and then reheated with the low-boiling-point working fluid in the regenerator. The temperature is controlled by the heat pump unit and the heating and cooling unit. When the specified mixing temperature is reached, it is sent to the mixer for mixing.

[0015] S2: The low-boiling-point working fluid enters the low-temperature working fluid pipeline from the low-temperature storage tank. It is first pressurized to the specified mixing pressure by the low-temperature working fluid pump, and then reheated with the high-temperature working fluid in the regenerator. When the specified mixing temperature is reached, it is sent to the mixer for mixing.

[0016] S3: When the heat released by the high-boiling-point working substance is greater than the heat absorbed by the low-boiling-point working substance, the high-boiling-point working substance needs to be heated. In this case, the heat is provided by the heat pump unit, and then the heat is delivered to the high-boiling-point working substance pipeline by the refrigerant through the heater / cooler. When the heat released by the high-boiling-point working substance is less than the heat absorbed by the low-boiling-point working substance, the high-boiling-point working substance needs to be cooled. In this case, the cooling capacity is provided by the heat pump unit, and then the cooling capacity is delivered to the high-boiling-point working substance pipeline by the refrigerant through the heater / cooler.

[0017] S4: After the high-boiling-point working fluid and the low-boiling-point working fluid are fully mixed in the mixer, the mixture will be sent to the blending tank to shorten the blending time and complete the preparation of the non-azeotropic refrigerant mixture.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. The present invention provides an apparatus and method for preparing a non-azeotropic mixed refrigerant, which can prepare a mixture containing multiple refrigerants with large differences in boiling point. By integrating a regenerator, a heat pump unit and a heating and cooling unit, it achieves efficient recovery and utilization of heat and cold energy. At the same time, it can achieve precise control of the temperature of the mixed refrigerant, ensuring that the mixing process in the mixer is a liquid-to-liquid mixing process, and further ensuring that the system can produce continuously throughout the year.

[0020] 2. The mixing tank equipped with this invention greatly accelerates the mixing speed of the working fluid, further improving production efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the mixture preparation process according to the apparatus and method for preparing a non-azeotropic mixed refrigerant as described in Embodiments 1 and 2 of the present invention, wherein the heating and cooling device adopts a two-in-one heat exchanger;

[0022] Figure 2 This is a schematic diagram of the mixture preparation process according to the apparatus and method for preparing a non-azeotropic mixed refrigerant as described in Embodiment 3 of the present invention, wherein the heating and cooling unit is split into two independent heat exchangers, both of which are set in the high-boiling-point working fluid pipeline.

[0023] Figure 3 This is a schematic diagram of the mixture preparation process according to the apparatus and method for preparing a non-azeotropic mixed refrigerant as described in Embodiment 4 of the present invention. The heating and cooling system is divided into two independent heat exchangers. The heater is set in the low-boiling-point working fluid pipeline, and the cooler is set in the high-boiling-point working fluid pipeline.

[0024] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, including: 1. High-boiling-point working fluid storage tank, 2. Low-boiling-point working fluid storage tank, 3. High-boiling-point working fluid pump, 4. Low-boiling-point working fluid pump, 5. Heater / cooler, 6. Heat pump unit, 7. Regenerator, 8. Flow meter, 9. Mixer, 10. Blending tank, 11. High-temperature side piping of regenerator, 12. Low-temperature side piping of regenerator, 13. High-boiling-point working fluid piping, 14. Low-boiling-point working fluid piping, 15. Refrigerant piping. Detailed Implementation

[0025] The technical method of the present invention will now be clearly and completely described with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] In specific implementations of this invention, the refrigerants used are all high-purity, environmentally friendly refrigerants commonly used in the fields of refrigeration and cryogenic technology. Table 1 provides the physical property parameters of the three refrigerants involved in the embodiments:

[0027] Table 1: Refrigerant Properties

[0028]

[0029] Example 1

[0030] The present invention employs the technical method for mixing environmentally friendly refrigerants propylene (R1270) and ethylene (R1150), wherein the heating and cooling system utilizes a combined heat exchanger. Furthermore, considering situations where the refrigerant in the cooling system does not possess a sufficiently low freezing point (e.g., water), the heating and cooling system is positioned before the inlet of the regenerator in the high-boiling-point working fluid pipeline, as shown in the attached diagram. Figure 1 As shown in Table 2, the contents of R1270 and R1150 refrigerants in the produced mixed refrigerant are 90wt% and 10wt%, respectively, and the operating conditions are set as shown in Table 2.

[0031] According to the method described in this embodiment, R1270 and R1150 are first adjusted to the specified mixing pressure by high and low temperature working fluid pumps. Before the working fluid enters the regenerator, depending on the different operating conditions, when the room temperature is 40°C in summer, the R1270 refrigerant needs to be cooled to the pre-mixing temperature of 0°C. At this time, the heat pump unit needs to work with the heater and cooler to supplement the cooling power of 444.92kW to cool the R1270 refrigerant to 12.67°C before it enters the regenerator for heat exchange. In winter, the heat pump unit needs to work with the heater and cooler to compensate for the heating power of 192.92kW to heat the R1270 refrigerant to 12.67°C before it enters the regenerator for heat exchange. In the regenerator, the two refrigerants exchange heat and reach the specified pre-mixing temperature and pressure before being sent together to the mixer and blending tank to complete the preparation of the refrigerant mixture in a specific ratio.

[0032] Example 2

[0033] The mixing of environmentally friendly refrigerants propylene (R1270) and ethane (R170) using the technical method provided by this invention has the same heater and cooler arrangement as in Example 1, as shown in the attached diagram. Figure 1 As shown in Table 3, the contents of R1270 and R170 refrigerants in the produced mixed refrigerant are 80wt% and 20wt%, respectively, and the operating conditions are set as shown in Table 3.

[0034] According to the method described in this embodiment, firstly, R1270 refrigerant and R170 refrigerant are adjusted to the mixing pressure by high and low temperature working fluid pumps respectively; before the working fluid enters the regenerator, depending on different operating conditions, when the room temperature is 40°C in summer, the heat release (Q) required for R1270 refrigerant to cool to the mixing temperature of 12.42°C is calculated. kThe heat absorbed (Q0) of R170 refrigerant when heated to the same mixing temperature is equal to that absorbed by the heat pump unit, so no additional work is required from the heat pump unit. However, when the room temperature is 0°C in winter, the heat pump unit needs to work with the heater and cooler to compensate for the heating power of 245.96kW to first heat the R1270 refrigerant to 18°C. Then, the two refrigerants exchange heat in the regenerator. When both working fluids reach the specified mixing pressure and mixing temperature, they are sent to the mixer for uniform mixing. Finally, the mixture is sent to the blending tank to shorten the mixing time and complete the preparation of the refrigerant mixture in a specific ratio.

[0035] Example 3

[0036] The mixing of environmentally friendly refrigerants propylene (R1270) and ethylene (R1150) using the technical method provided by this invention involves separate heater and cooler configurations. Furthermore, considering situations where the refrigerant in the heat transfer fluid line does not have a sufficiently low freezing point (e.g., water), the heater needs to be positioned before the inlet of the regenerator in the high-boiling-point working fluid line, as shown in the attached diagram. Figure 2 As shown in Table 4, the contents of R1270 and R1150 refrigerants in the produced mixed refrigerant are 90wt% and 10wt%, respectively, and the operating conditions are set as shown in Table 4.

[0037] According to the method described in this embodiment, R1270 and R1150 are first adjusted to the mixing pressure by high and low temperature working fluid pumps respectively; then, the two refrigerants exchange heat in the regenerator; after the working fluid flows out of the regenerator, depending on different operating conditions, when the room temperature is 30°C in summer, the R1270 refrigerant needs to be cooled to -5°C, requiring a heat pump unit to supplement the cooling power of 350.97kW in conjunction with the cooler; while in winter, before the R1270 refrigerant enters the regenerator, it needs to be heated to 7.84°C by the heat pump unit and heater to compensate for the heating power of 118.59kW before entering the regenerator for heat exchange, and finally mixed and blended with R1150 at the same mixing temperature to complete the preparation of a specific ratio of mixed refrigerant.

[0038] Example 4

[0039] The mixing of environmentally friendly refrigerants propylene (R1270) and ethylene (R1150) using the technical method provided by this invention involves separate heater and cooler installations. Considering the use of a sufficiently low freezing point refrigerant (e.g., ethylene glycol aqueous solution) in the refrigerant pipeline, the heater can be positioned after the outlet of the regenerator in the low-boiling-point working fluid pipeline, as shown in the attached diagram. Figure 3 As shown in Table 5, the contents of R1270 and R1150 refrigerants in the produced mixed refrigerant are 90wt% and 10wt%, respectively, and the operating conditions are set as shown in Table 5.

[0040] According to the method described in this embodiment, the working principle is the same as in embodiment 3 under summer conditions. However, under winter conditions, taking the conditions shown in Table 5 as an example, the heat pump unit needs to work with the heater to supplement the heating power of 118.59kW to heat the R1150 refrigerant to a mixing temperature of -5°C. After both working fluids reach the specified mixing pressure and mixing temperature, they are then fed into the mixer and blending tank to complete the preparation of a specific ratio of mixed refrigerant.

[0041] Table 2: Operating conditions of Example 1 (R1270 and R1150 flow rates: 22.5 t / h and 2.5 t / h)

[0042]

[0043] Table 3: Operating conditions of Example 2 (R1270 and R170 flow rates: 20t / h and 2t / h)

[0044]

[0045] Table 4: Operating conditions of Example 3 (R1270 and R1150 flow rates: 22.5 t / h and 2.5 t / h)

[0046]

[0047] Table 5: Operating conditions of Example 4 (R1270 and R1150 flow rates: 22.5 t / h and 2.5 t / h)

[0048]

[0049] The apparatus and method for preparing non-azeotropic mixed refrigerants provided in Examples 1-4 can effectively solve the key problems faced by the production technology of mixing refrigerants with large boiling point differences, such as long gas-liquid two-phase mixing time, easy generation of heat of solution, and unstable mixture ratio. This invention is designed with a regenerator for solution reheating, which can fully utilize the heat and cold of the high and low temperature working fluids to reduce system energy consumption; in conjunction with a heat pump unit and a heater / cooler, it achieves precise control of the working fluid temperature, ensuring liquid-liquid mixing within the mixer and guaranteeing a stable ratio of the produced mixed refrigerant; the heater / cooler can be arranged according to the properties of the heat pump unit's refrigerant, solving the problem of heater pipe freezing caused by using refrigerants with low freezing points; at the same time, a mixer and a mixing tank are used to further shorten the mixing time of the mixture, ensuring thorough mixing.

[0050] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An apparatus for preparing a non-azeotropic refrigerant mixture, characterized in that, The device includes a high-boiling-point working fluid storage tank, a low-boiling-point working fluid storage tank, a high-boiling-point working fluid pump, a low-boiling-point working fluid pump, a heat pump unit, a heater / cooler, a regenerator, a pressure gauge, a thermometer, a flow meter, a mixer, a blending tank, a high-temperature side pipeline of the regenerator, a low-temperature side pipeline of the regenerator, a high-boiling-point working fluid pipeline, a low-boiling-point working fluid pipeline, and a refrigerant pipeline. Before the high- and low-temperature working fluids enter the mixer, the device is divided into a high-boiling-point working fluid pipeline and a low-boiling-point working fluid pipeline. The high-boiling-point working fluid pipeline is sequentially connected to the high-boiling-point working fluid storage tank, the high-boiling-point working fluid pump, the heater / cooler, the high-temperature side pipeline of the regenerator, and the flow meter. The low-boiling-point working fluid pipeline is sequentially connected to the low-boiling-point working fluid storage tank, the low-boiling-point working fluid pump, the low-temperature side pipeline of the regenerator, and the flow meter. In the high-boiling-point working fluid pipeline, the outlet of the high-boiling-point working fluid storage tank is connected to the inlet of the high-boiling-point working fluid pump; the outlet of the high-boiling-point working fluid pump is connected to the inlet of the heater / cooler; the outlet of the heater / cooler is connected to the inlet of the high-temperature side pipeline of the regenerator; the outlet of the high-temperature side pipeline of the regenerator is connected to the inlet of the flow meter; and the outlet of the flow meter is connected to the inlet of the mixer. In the low-boiling-point working fluid pipeline, the outlet of the low-boiling-point working fluid storage tank is connected to the inlet of the low-boiling-point working fluid pump; the outlet of the low-boiling-point working fluid pump is connected to the inlet of the low-temperature side pipeline of the regenerator; the outlet of the low-temperature side pipeline of the regenerator is connected to the inlet of the flow meter; and the outlet of the flow meter is connected to the inlet of the mixer. The outlet of the mixer is connected to the inlet of the blending tank. The heater / cooler is connected to the heat pump unit via a refrigerant pipeline. The high-boiling-point working fluid storage tank is located at ambient temperature and is used to store high-boiling-point working fluids. The ambient temperature is -5 to 30°C. At least one high-boiling-point working fluid is present, with a boiling point not lower than -60°C and a critical temperature higher than the ambient temperature. The low-boiling-point working fluid storage tank is a vacuum-insulated tank used to store low-boiling-point working fluids. At least one low-boiling-point working fluid is present, with a boiling point at least 30°C lower than the boiling point of the high-boiling-point working fluid. The high-boiling-point working fluid pump is used to adjust the pressure of the high-boiling-point working fluid to a mixing pressure, and the low-boiling-point working fluid pump is used to adjust the pressure of the low-boiling-point working fluid to a mixing pressure.

2. The apparatus for preparing a non-azeotropic refrigerant mixture according to claim 1, characterized in that, The boiling point of the low-boiling-point working fluid is 41-122°C lower than that of the high-boiling-point working fluid.

3. The apparatus for preparing a non-azeotropic refrigerant mixture according to claim 1, characterized in that, The pressure gauge, thermometer, and flow meter are used to measure or monitor the physical state of the high-boiling-point working fluid and the low-boiling-point working fluid. The regenerator is a counter-flow or cross-flow heat exchanger used to reheat the high-boiling-point working fluid and the low-boiling-point working fluid.

4. The apparatus for preparing a non-azeotropic refrigerant mixture according to claim 1, characterized in that, The heat pump unit and the heater / cooler are connected through a refrigerant pipeline to form a circuit for transferring heat or cold, which is used to compensate for the heat exchange between the high- and low-temperature working fluids so that the high-boiling-point working fluid and the low-boiling-point working fluid reach the same temperature before mixing.

5. The apparatus for preparing a non-azeotropic refrigerant mixture according to claim 1, characterized in that, The heating and cooling device is a combined heating and cooling heat exchanger; when the refrigerant in the refrigerant pipeline does not have a sufficiently low freezing point, in order to prevent the refrigerant from freezing, the combined heating and cooling heat exchanger is installed in the high boiling point working fluid pipeline.

6. The apparatus for preparing a non-azeotropic refrigerant mixture according to claim 1, characterized in that, The heating and cooling system is configured with two heat exchangers: a heater and a cooler. The heater is installed in the low-boiling-point working fluid pipeline, and the cooler is installed in the high-boiling-point working fluid pipeline. When the refrigerant in the refrigerant pipeline does not have a sufficiently low freezing point, both the heater and the cooler are installed in the high-boiling-point working fluid pipeline to prevent the refrigerant from freezing.

7. The apparatus for preparing a non-azeotropic refrigerant mixture according to claim 1, characterized in that, The mixer is connected to the mixing tank to ensure thorough mixing of the refrigerant while shortening the mixing time.

8. A method for preparing a non-azeotropic refrigerant mixture using the apparatus according to any one of claims 1-7, comprising the following steps: S1: The high-boiling-point working fluid enters the high-boiling-point working fluid pipeline from the high-boiling-point working fluid storage tank. It is first pressurized to the specified mixing pressure by the high-boiling-point working fluid pump, and then reheated with the low-boiling-point working fluid in the regenerator. The temperature is controlled by the heat pump unit and the heating and cooling unit. When the specified mixing temperature is reached, it is sent to the mixer for mixing. S2: The low-boiling-point working fluid enters the cryogenic working fluid pipeline from the low-boiling-point working fluid storage tank. It is first pressurized to the specified mixing pressure by the cryogenic working fluid pump, and then reheated with the high-temperature working fluid in the regenerator. When the specified mixing temperature is reached, it is sent to the mixer for mixing. S3: When the heat released by the high-boiling-point working substance is greater than the heat absorbed by the low-boiling-point working substance, the high-boiling-point working substance needs to be heated. In this case, the heat is provided by the heat pump unit, and then the refrigerant delivers the heat to the high-boiling-point working substance pipeline through the heater / cooler. When the heat released by the high-boiling-point working substance is less than the heat absorbed by the low-boiling-point working substance, the high-boiling-point working substance needs to be cooled. In this case, the cooling capacity is provided by the heat pump unit, and then the cooling capacity is delivered to the high-boiling-point working substance pipeline through the heater / cooler. S4: After the high-boiling-point working fluid and the low-boiling-point working fluid are fully mixed in the mixer, the mixture will be sent to the blending tank to shorten the blending time and complete the preparation of the non-azeotropic refrigerant mixture.

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