Cascade refrigeration system

Abstract

The utility model provides a cascade type industrial refrigerating system and aims to solve the problems that in the process of converting a low-temperature section cooling flow path into a high-temperature section cooling flow path in an existing cascade type refrigerating system, when gas (the outlet temperature is 80 + / -2 DEG C) at an outlet of a low-temperature section compressor directly enters a cascade type condenser, the environment temperature is not utilized, and the temperature of the gas is too high. And the operation load of the high-temperature section compressor is increased. The refrigerating system comprises a cascade condenser, a high-temperature-section condensation flow path and a low-temperature-section condensation flow path, an evaporative cooler is further connected to the output end of the low-temperature-section condensation path, and therefore the high outlet temperature in the low-temperature-section condensation flow path is replaced through the evaporative cooler by means of the environment temperature; therefore, the temperature before low-temperature backflow enters the cascade condenser is reduced, and the power consumption of the compressor at the high-temperature section is effectively reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of industrial refrigeration systems, in particular to a cascade refrigeration system. Background Art

[0002] The cascade refrigeration system divides the larger total temperature difference into a high-temperature section and a low-temperature section, selects a suitable refrigerant cycle according to the temperature zone of each section, and then stacks them up, using the cooling capacity of the high-temperature section to bear the condensation load of the low-temperature section, thereby obtaining a lower cooling temperature.

[0003] At present, R23 is used as the technology of -70℃ refrigeration process in industrial refrigeration system, and R23 and R22 cascade refrigeration are mostly used. This process system was first developed by York. The system is divided into high temperature section and low temperature section. Its principle is to use R22 to absorb the carrier heat of R23 in the heat exchanger to change the gaseous R23 into liquid R23. The liquid R23 cools the process system due to the physical change of phase change in the evaporator. The process flow is as follows: liquid R23 exchanges heat with the medium in the evaporator and becomes gaseous R23 which enters the refrigeration unit (this unit is called the low-pressure compressor). After the refrigeration unit is pressurized to 13 bar, it directly enters the cascade cooler, exchanges heat with -40℃ R22 in the cascade condenser, becomes liquid R23, and is stored in the storage tank. Under the action of the compressor outlet pressure, it enters the evaporator for recycling. The -40℃ R22 undergoes phase change and absorbs heat in the cascade cooler to become gaseous R22. It enters the refrigeration unit (this unit is called the high-temperature compressor), is pressurized, and is cooled to liquid R22 through evaporative cooling and enters the storage tank. Then, it enters the cascade cooler under the action of the high-temperature unit outlet pressure for recycling.

[0004] Existing cascade refrigeration equipment usually uses two sets of refrigeration circuits and cascade condensers for cascade refrigeration. The refrigerant from the low-pressure compressor in the low-temperature section, such as R23, directly enters the cascade condenser. The exhaust temperature of the R23 unit is 80℃±2. This part of the gas needs to be condensed by the R22 unit in the cascade condenser, and the ambient temperature is not used. Therefore, the high-temperature section unit has high energy consumption. When operating in the summer in the north, the number of R22 units turned on is large. When operating in the winter, the ambient temperature cannot be used, resulting in increased operating power consumption of the high-temperature section unit.

[0005] Therefore, it is of great significance to study a method that can effectively reduce the energy consumption of high-temperature compressors in cascade cooling systems. Summary of the invention

[0006] In order to solve the problem of high energy consumption caused by high temperature outlet temperature of low temperature section in cascade refrigeration system in the prior art, the high temperature section compressor unit causes high energy consumption in order to reduce the air flow temperature, the utility model adopts the following technical solutions:

[0007] Cascade refrigeration system, comprising:

[0008] A cascade condenser, wherein the cascade condenser has a first output end, a first input end, a second output end, and a second input end;

[0009] A high-temperature section condensation flow path, wherein the input end of the high-temperature section condensation flow path is connected to the first output end, and the output end is connected to the first input end;

[0010] a low-temperature section condensation flow path, wherein the input end of the low-temperature section condensation flow path is connected to the second output end; and

[0011] An evaporative cooler, wherein the input end of the evaporative cooler is connected to the output end of the low-temperature section condensation flow path, and the output end of the evaporative cooler is connected to the second input end.

[0012] The refrigeration system of the utility model is based on the existing technology, and an evaporative cooler is added at the end of the low-temperature section condensation flow path. The high-temperature (80℃±2) gaseous R23 at the outlet of the low-temperature section unit is first cooled by the evaporative cooler before entering the cascade condenser for condensation. When entering the cascade condenser again, the high-temperature airflow is cooled after temperature exchange with the external environment. In this way, the cascade condenser will not cool itself down, thereby reducing the energy consumption in the high-temperature section unit.

[0013] The working principle of the evaporative cooler is mainly to use the partial evaporation of the spray water outside the coil to take away the heat released during the condensation process of the gaseous refrigerant. The high-temperature gaseous refrigerant enters the coil from the refrigerant inlet on the upper part of the coil, and exchanges heat with the spray water outside the coil and the ambient air, so that the refrigerant is cooled in advance before entering the cascade cooling. The evaporative condenser is composed of a fan, condensing coil, water collector, air inlet shutters and other box components, and the energy-saving effect is remarkable, especially in the northern winter.

[0014] As the preferred technical solution:

[0015] In the cascade refrigeration system as described above, the high temperature section condensation flow path comprises:

[0016] A gas-liquid separator, one end of which is connected to the first output end of the cascade condenser, and the other end of which is connected to the high-temperature section compressor, and is used to separate the gaseous refrigerant and the liquid refrigerant discharged from the cascade condenser, the gaseous refrigerant being located at the upper end of the gas-liquid separator, and the liquid refrigerant being located at the bottom of the gas-liquid separator;

[0017] The high temperature section compressor is connected to the top of the gas-liquid separator at one end and to the condenser at the other end, and is used to condense the outlet refrigerant of the high temperature section compressor. The gaseous refrigerant discharged from the compressor contacts the evaporative cold environment temperature inside the cooler, and the gaseous refrigerant is condensed into liquid refrigerant.

[0018] The condenser is connected to the high-temperature compressor at one end and to the economizer at the other end. The economizer is a heat exchanger that absorbs heat through the self-throttling evaporation of the refrigerant to supercool the other part of the refrigerant. In the high-temperature system, the liquid from the condenser is divided into two paths. One path absorbs part of the heat and evaporates into gas to return to the compressor, and the other path of refrigerant is supercooled and enters the cascade evaporation to evaporate and then return to the compressor; and,

[0019] The economizer comprises:

[0020] An input terminal A, connected to the condenser;

[0021] Output terminal B is connected to the high-temperature compressor and is used to recover the gas evaporated by the economizer after absorbing part of the heat;

[0022] The output end C is connected to the input end of the cascade condenser and is used for the supercooled liquid to enter the cascade cooling and low temperature section R23 heat exchange condensation.

[0023] In the cascade refrigeration system as described above, a thermosiphon tank and a storage tank are also arranged in series in the pipeline connecting the condenser and the economizer input end A. The working principle of the thermosiphon tank is mainly based on the physical principle that hot air rises. The liquid condensed by evaporation first enters the thermosiphon tank, and is connected to the compressor oil cooler through the pipeline at the bottom of the thermosiphon tank. After absorbing heat, it enters the condenser, and the excess condensed liquid is drawn out from the middle of the siphon tank and enters the storage tank. The storage tank serves as a storage function for the refrigerant.

[0024] In the cascade refrigeration system as described above, a back pressure valve and a check valve are provided on the pipeline connecting the output end B of the economizer and the high temperature section compressor.

[0025] In the cascade refrigeration system as described above, a regulating valve is provided on the pipeline connecting the condenser and the input end A of the economizer to adjust the flow rate of the liquid entering the cascade refrigeration system.

[0026] In the cascade refrigeration system as described above, the pressure value of the high temperature section compressor when working is 13~15 bar.

[0027] In the cascade refrigeration system as described above, the low temperature section condensation flow path comprises:

[0028] A low-temperature storage tank, one input end of which is connected to the second output end of the cascade condenser, and the output end of which is connected to the input end of the regenerator, and the low-temperature storage tank is used for draining oil;

[0029] The regenerator has one output end connected to the input end of the evaporator and the other output end connected to the low-temperature compressor. The function of the regenerator is to prevent the gas entering the compressor from carrying liquid and causing damage to the compressor.

[0030] The output end of the evaporator is connected to the input end of the gas-liquid separator, and the output end of the gas-liquid separator is connected to the regenerator. The gaseous and liquid refrigerants are refluxed to the regenerator for secondary evaporation under the action of the gas-liquid separator. The function of the evaporator is to reduce the content of dichloromethane in the system. Dichloromethane is a cooling solvent in the refrigeration system, which is used to reduce the separation and condensation of the medium of the process system. After the liquid R23 exchanges heat with dichloromethane in the evaporator, it enters the gas-liquid separator and is separated by gravity before entering the low-temperature compressor to prevent the gas entering the compressor from carrying liquid and causing liquid hammer of the compressor.

[0031] The low-temperature compressor has one output end connected to the pipeline connected to the cascade condenser and connected to the evaporative cooler, and the other output end is connected to the input end of the pressure maintenance unit; it is used to reduce the temperature entering the cascade condenser, and the evaporative cooler plays a role in energy saving and consumption reduction, and the other output end is connected to the input end of the pressure maintenance unit for system safety in an emergency state;

[0032] The pressure maintaining unit has an output end connected to the other input end of the cryogenic storage tank to prevent R23 from vaporizing and overpressure in a fault state. The vaporized R23 under the action of the pressure maintaining unit flows back to the cryogenic storage tank for recycling.

[0033] In the cascade refrigeration system as described above, a solenoid valve is provided on the pipeline connecting the regenerator and the evaporator for controlling the liquid level of the evaporator.

[0034] In the cascade refrigeration system as described above, the pressure value of the low temperature section compressor when working is 13~14 bar.

[0035] In the cascade refrigeration system as described above, a thermometer is provided on the inlet pipe connecting the low-temperature section condensing flow path with the evaporative cooler, and a remote thermometer is provided on the pipeline connecting the evaporative cooler with the cascade condenser for observing and adjusting the workload of the evaporative cooler.

[0036] Compared with the prior art, the beneficial effects of the utility model are:

[0037] 1. The cascade refrigeration system of the utility model is provided with an evaporative cooler at the end of the original low-temperature section condensation flow path. The high-temperature (80°C ± 2) gaseous R23 at the outlet of the low-temperature section unit is first cooled by the evaporative cooler before entering the cascade condenser for condensation. When entering the cascade condenser again, the high-temperature airflow is cooled after temperature exchange with the external environment. In this way, the cascade condenser will not cool itself down, thereby reducing the energy consumption in the high-temperature section unit.

[0038] 2. In the cascade refrigeration system of the present invention, the evaporative cooler can be installed in parallel or in series between the low-temperature section condensation flow path and the cascade cooling. Its use function has no effect on the process system, reducing the limitation of the site for equipment installation.

[0039] 3. In the cascade refrigeration system of the present invention, a thermometer is provided on the inlet pipe connecting the low-temperature section condensing flow path with the evaporative cooler, and a remote thermometer is provided on the pipe connecting the outlet of the evaporative cooler with the cascade condenser, for observing and adjusting the working load of the evaporative cooler. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 This is the working flow chart of the cascade refrigeration system of the utility model;

[0042] Figure 2 It is a structural schematic diagram of the cascade refrigeration system of the utility model.

[0043] Reference numerals:

[0044] 1-High temperature section condensation flow path; 1.1-Gas-liquid separator; 1.2-High temperature section compressor; 1.3-Condenser; 1.4-Thermosyphon storage tank; 1.5-Storage tank; 1.6-Economizer; 2-Cascade condenser; 3-Low temperature section condensation flow path; 3.1-Low temperature storage tank; 3.2-Regenerator; 3.3-Evaporator; 3.4-Gas-liquid separator; 3.5-Low temperature section compressor; 3.6-Pressure maintenance unit; 4-Evaporative cooler. DETAILED DESCRIPTION

[0045] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0046] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of the present invention are conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0047] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0048] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0050] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0051] The embodiments of the present invention / utility model are described in detail below with reference to the accompanying drawings.

[0052] The utility model embodiment provides a cascade refrigeration system, such as Figure 1 As shown, the cascade refrigeration system comprises:

[0053] A cascade condenser, wherein the cascade condenser has a first output end, a first input end, a second output end, and a second input end;

[0054] A high-temperature section condensation flow path, wherein the input end of the high-temperature section condensation flow path is connected to the first output end, and the output end is connected to the first input end;

[0055] A low-temperature condensation flow path, wherein an input end of the low-temperature condensation flow path is connected to the second output end; and

[0056] An evaporative cooler, wherein the input end of the evaporative cooler is connected to the output end of the low-temperature section condensation flow path, and the output end of the evaporative cooler is connected to the second input end.

[0057] The structures of the high-temperature section condensation flow path and the low-temperature section condensation flow path of the utility model are as follows: Figure 2 As shown:

[0058] The high temperature section condensation flow path 1 includes:

[0059] A gas-liquid separator 1.1, one end of which is connected to the first output end of the cascade condenser 2, and the other end of which is connected to the high-temperature section compressor 1.2;

[0060] The high temperature section compressor 1.2 has one end connected to the top of the gas-liquid separator 1.1 and the other end connected to the condenser 1.3. The pressure value of the high temperature section compressor 1.2 during operation is 13-15 bar.

[0061] The condenser 1.3 is connected to the high temperature section compressor 1.2 at one end and to the economizer 1.6 at the other end. Alternatively, the pipeline connecting the condenser 1.3 and the input end of the economizer 1.6 is also provided with a thermosyphon storage tank 1.4 and a storage tank 1.5 in series;

[0062] as well as,

[0063] Economizer 1.6, including:

[0064] Input terminal A, connected to condenser 1.3;

[0065] Output terminal B is connected to high temperature section compressor 1.2;

[0066] The output terminal C is connected to the input terminal of the cascade condenser 2.

[0067] A back pressure valve and a check valve are provided on the pipeline connecting the output end B of the economizer 1.6 and the high temperature section compressor 1.2.

[0068] A regulating valve is provided on the pipeline connecting the condenser 1.3 and the input end A of the economizer 1.6.

[0069] The low temperature section condensation flow path 3 includes:

[0070] A low temperature storage tank 3.1, one input end of which is connected to the second output end of the cascade condenser 2, and the output end of which is connected to the input end of the regenerator 3.2;

[0071] The regenerator 3.2 has one output end connected to the input end of the evaporator 3.3, and the other output end connected to the low-temperature section compressor 3.5. A solenoid valve is provided on the pipeline connecting the regenerator 3.2 and the evaporator 3.3;

[0072] The output end of the evaporator 3.3 is connected to the input end of the gas-liquid separator 3.4, and the output end of the gas-liquid separator 3.4 is connected to the regenerator 3.2. Under the action of the gas-liquid separator, the gaseous and liquid refrigerants flow back to the regenerator for secondary evaporation.

[0073] The low temperature section compressor 3.5 has one output end connected to the input end of the evaporative cooler 4, and the other output end connected to the input end of the pressure maintaining unit 3.6; the pressure value of the low temperature section compressor 3.5 when working is 13~14bar.

[0074] The output end of the pressure maintaining unit 3.6 is connected to the other input end of the cryogenic storage tank 3.1.

[0075] The utility model is provided with a thermometer on an inlet pipeline connecting a low-temperature section condensation flow path with an evaporative cooler, and a remote thermometer is provided on a pipeline connecting an outlet of the evaporative cooler with a cascade condenser.

[0076] The utility model relates to a cascade refrigeration system, in which an evaporative cooler is connected to the outlet of the low-temperature section condensation flow path of the original refrigeration system, so as to exchange the high-temperature R23 medium at the outlet of the low-temperature section condensation flow path with the ambient temperature, and effectively reduces the R23 medium from being pre-cooled by the ambient temperature before entering the cascade condenser, thereby reducing the load of the R22 unit and reducing the power consumption of the equipment.

[0077] After the application of the cascade refrigeration system of the utility model, on the one hand, the ambient temperature is efficiently utilized, and the number of R22 units to be started is reduced. According to calculation, the annual operating cost is saved by about: 3.23 million yuan (Silicon Energy high temperature unit model: RWFII856, equipped with motor rated power: 1230kW, based on 8760 annual operating hours, 0.3 yuan per kilowatt-hour, 1230*0.3*8760=3232440 yuan); on the other hand, during the process operation, extreme high temperature weather can also be smoothly passed, and the stability of the system will be more reliable.

Claims

1. Cascade refrigeration system, characterized by: include: A cascade condenser, wherein the cascade condenser has a first output end, a first input end, a second output end, and a second input end; A high-temperature section condensation flow path, wherein the input end of the high-temperature section condensation flow path is connected to the first output end, and the output end is connected to the first input end; A low-temperature section condensation flow path, wherein an input end of the low-temperature section condensation flow path is connected to the second output end; as well as, An evaporative cooler, wherein the input end of the evaporative cooler is connected to the output end of the low-temperature section condensation flow path, and the output end of the evaporative cooler is connected to the second input end.

2. The cascade refrigeration system according to claim 1, characterized in that: The high temperature section condensation flow path comprises: A gas-liquid separator, one end of which is connected to the first output end of the cascade condenser, and the other end of which is connected to the high-temperature section compressor; The high temperature section compressor has one end connected to the top of the gas-liquid separator and the other end connected to the condenser; The condenser has one end connected to the high temperature section compressor and the other end connected to the economizer; and The economizer comprises: An input terminal A connected to the condenser; Output terminal B is connected to the high temperature section compressor; The output terminal C is connected to the input terminal of the cascade condenser.

3. The cascade refrigeration system according to claim 2, characterized in that: A thermosiphon storage tank and a storage tank are also arranged in series in the pipeline connecting the condenser and the economizer input end A.

4. The cascade refrigeration system according to claim 3, characterized in that: A back pressure valve and a check valve are provided on the pipeline connecting the output end B of the economizer and the high temperature section compressor.

5. The cascade refrigeration system according to claim 4, characterized in that: A regulating valve is provided on the pipeline connecting the condenser and the input end A of the economizer.

6. The cascade refrigeration system according to claim 2, characterized in that: The pressure value of the high temperature section compressor when working is 13~15bar.

7. The cascade refrigeration system according to claim 1, characterized in that: The low temperature section condensation flow path comprises: A low-temperature storage tank, one input end of which is connected to the second output end of the cascade condenser, and the output end of which is connected to the input end of the regenerator; The regenerator has one output end connected to the input end of the evaporator and the other output end connected to the low temperature section compressor; The evaporator, its output end is connected to the gas-liquid separator input end; The gas-liquid separator has an output end connected to the regenerator, and the gaseous and liquid refrigerants flow back to the regenerator under the action of the gas-liquid separator for secondary evaporation; The low temperature section compressor has one output end connected to the pipeline connected to the cascade condenser and connected to the evaporative cooler, and the other output end connected to the input end of the pressure maintaining unit; The output end of the pressure maintaining unit is connected to the other input end of the low-temperature storage tank.

8. The cascade refrigeration system according to claim 7, characterized in that: A solenoid valve is arranged on the pipeline connecting the regenerator and the evaporator.

9. The cascade refrigeration system according to claim 7, characterized in that: The pressure value of the low temperature section compressor when working is 13~14 bar.

10. The cascade refrigeration system according to claim 1, characterized in that: A thermometer is provided on the inlet pipe connecting the low-temperature section condensation flow path and the evaporative cooler, and a remote thermometer is provided on the pipeline connecting the evaporative cooler and the cascade condenser.

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