Compression refrigeration system and chiller

Abstract

The present invention provides a compression refrigeration system and a chiller, which relate to the technical field of refrigeration systems. The system reduces the number of front-end compressors and reduces the refrigerant diversion by connecting multiple compressors in parallel and then in series. The compression refrigeration system includes a compression module 1 and a compression module 2, wherein the compression module 1 and the compression module 2 are connected in series and the refrigerant discharged from the compression module 1 can flow to the compression module 2, and the compression module 1 includes at least two compressors and the compressors in the compression module 1 are connected in parallel. The present invention is used to improve the problem of uneven air intake distribution caused by too many compressors connected in parallel, and improve the COP of the system and reduce the system power.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration systems, and in particular to a compression refrigeration system and a chiller with an outlet water temperature below 0°C and chilled water being low-temperature ethylene glycol or brine. Background Art

[0002] At present, in the existing parallel screw compressor refrigeration system, as the number of parallel compressors increases, in order to ensure the uniform air intake of each compressor, it is generally necessary to install an air collecting tank in front of the compressor, which increases the cost. After the air collecting tank is installed, the refrigerant gas at the inlet connecting pipe of the air collecting tank will generate vortexes, which affects the uniformity of air distribution of each compressor and cannot bring out the best performance of each compressor during operation. Summary of the invention

[0003] The object of the present invention is to provide a compression refrigeration system and a chiller, which adopts the method of connecting multiple compressors in parallel and then in series, so as to reduce the number of front-end compressors and reduce the refrigerant diversion. The preferred technical solutions among the many technical solutions provided by the present invention can produce many technical effects as described below.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] The present invention provides a compression refrigeration system, comprising compression module one and compression module two, wherein the compression module one and the compression module two are connected in series and the refrigerant discharged from the compression module one can flow to the compression module two, and the compression module one comprises at least two compressors and the compressors in the compression module one are connected in parallel.

[0006] Further, the number of compressors in the compression module two is one; or, the number of compressors in the compression module two is more than two, and the compressors in the compression module two are connected in parallel.

[0007] Furthermore, all the compressors in the compression module one are the same; all the compressors in the compression module two are the same; the compressors in the compression module one are the same as or different from the compressors in the compression module two.

[0008] Furthermore, the compressors in the compression module one are all screw compressors; and the compressors in the compression module two are all screw compressors.

[0009] Furthermore, the compression refrigeration system also includes an evaporator, and the refrigerant passing through the evaporator can be directly discharged to the compression module one, or the refrigerant passing through the evaporator flows to the drying filter and then can be discharged to the compression module one.

[0010] Furthermore, the compression refrigeration system also includes a liquid accumulator, and a gas outlet of the liquid accumulator is connected to the pipeline between the compression module 1 and the compression module 2 through a pressure compensation pipeline.

[0011] Furthermore, an expansion valve is provided on the pressure compensation pipeline.

[0012] Furthermore, an oil separator is connected to the pipeline on the outlet side of the compression module 1 and the pipeline on the outlet side of the compression module 2.

[0013] Furthermore, the compression refrigeration system also includes an evaporator and a condenser, and both the evaporator and the condenser are shell and tube heat exchangers.

[0014] A water chiller comprises the compression refrigeration system.

[0015] The compression refrigeration system provided by the present invention changes the parallel screw low-temperature refrigeration system into a compressor adopting the "parallel first and then series working mode", that is, the compressor in parallel at the front end is called compression module one, and the compressor in series with compression module one at the rear end is called compression module two, and the refrigerant discharged from compression module one can flow to compression module two. The number of front-end compressors is reduced in the system, and the problem of uneven air intake distribution caused by too many front-end compressors is improved; the "parallel first and then series working mode" is adopted compared to the full parallel connection of compressors in the prior art, and under the same air intake volume, the total power of the compressors in the system is low. In addition, since the refrigerant flowing to compression module two is a refrigerant with a certain temperature and a certain pressure, the compression efficiency of the compressor in compression module two is improved, and the COP of the system is improved.

[0016] The preferred technical solution of the present invention can at least produce the following technical effects:

[0017] Connecting multiple compressors in parallel and then in series can reduce the number of front-end compressors, reduce refrigerant diversion, and ensure relatively uniform gas distribution at the suction end of each parallel compressor, eliminating the gas collecting tank and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention 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 invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 Schematic diagram of the principle of the compression refrigeration system provided by the embodiment of the present invention

[0020] Figure 2It is a refrigeration cycle pressure-enthalpy diagram of a compression refrigeration system provided in an embodiment of the present invention.

[0021] In the figure, 1 is the first screw compressor; 2 is the first vertical oil separator; 3 is the second vertical oil separator; 4 is the third screw compressor; 5 is the condenser; 6 is the economizer; 7 is the first electronic expansion valve; 8 is the regulating valve; 9 is the drying filter; 10 is the safety valve; 11 is the stop valve; 12 is the liquid storage tank; 13 is the stop valve; 14 is the second electronic expansion valve; 15 is the evaporator; 16 is the second drying filter; 17 is the second screw compressor. DETAILED DESCRIPTION

[0022] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0023] See also Figure 1 and Figure 2 The present invention provides a compression refrigeration system, including compression module 1 and compression module 2, wherein compression module 1 and compression module 2 are connected in series and the refrigerant discharged from compression module 1 can flow to compression module 2, and compression module 1 includes at least two compressors and the compressors in compression module 1 are connected in parallel. In the existing screw compressor refrigeration system, as the demand for refrigeration capacity increases, the number of screw compressors in parallel in the system increases. In order to ensure that the air intake of each compressor is uniform as much as possible, a gas collecting tank is generally required to be installed in front of the screw compressor; the compression refrigeration system provided by the present invention changes the parallel screw low-temperature refrigeration system into a compressor adopting a "parallel first and then series working mode", that is, the compressor in parallel at the front end is called compression module 1, and the compressor in series with compression module 1 at the rear end is called compression module 2, and the refrigerant discharged from compression module 1 can flow to compression module 2. The number of front-end compressors is reduced in the system, and the problem of uneven air intake caused by too many front-end compressors is improved. The "parallel first and then series working mode" is adopted in contrast to the full parallel connection of compressors in the prior art. Under the same air intake volume, the total power of the compressors in the system is low. In addition, since the refrigerant flowing to the compression module 2 is a refrigerant with a certain temperature and a certain pressure, the compression efficiency of the compressor in the compression module 2 is improved, and the COP of the system is improved. Figure 2 The suction pressure and temperature of the compression module 2 are relatively large, which increases Figure 2 The isentropic compression efficiency of the CD process is improved, thereby improving the COP of the compression refrigeration system.

[0024] As an optional implementation of the embodiment of the present invention, the number of compressors in the compression module 2 is one; or, the number of compressors in the compression module 2 is two or more, and the compressors in the compression module 2 are connected in parallel. Figure 1 , indicating that the number of compressors in compression module 2 is one. Regarding the number of compressors in compression module 1 and the number of compressors in compression module 2, it is necessary to reasonably arrange the number of compression modules 1 and compression modules 2 according to actual conditions.

[0025] All compressors in compression module 1 are the same; all compressors in compression module 2 are the same; the compressors in compression module 1 are the same as or different from the compressors in compression module 2; the compressors in compression module 1 are all screw compressors, and the compressors in compression module 2 are all screw compressors, see Figure 1 The compressor in compression module 1 is the same as the compressor in compression module 2, compressing the refrigeration system. Of course, the compressor in compression module 1 and the compressor in compression module 2 can also be other compressors except screw compressors.

[0026] As an optional implementation of the embodiment of the present invention, the compression refrigeration system also includes an evaporator, and the refrigerant passing through the evaporator can be directly discharged to the compression module 1, or the refrigerant passing through the evaporator can flow to the drying filter and then be discharged to the compression module 1. Multiple compressors are first connected in parallel and then in series, so that the number of front-end compressors is reduced, the refrigerant diversion is reduced, and the air distribution at the suction end of each parallel compressor is relatively uniform, and the air collecting tank can be eliminated, reducing costs.

[0027] As an optional implementation of the embodiment of the present invention, the compression refrigeration system further includes a liquid reservoir 12, and the gas outlet of the liquid reservoir 12 is connected to the pipeline between the compression module 1 and the compression module 2 through a pressure-compensating pipeline. A first electronic expansion valve 7 is provided on the pressure-compensating pipeline. Through the first electronic expansion valve 7, the gas flow from the gas outlet of the liquid reservoir 12 to the compression module 2 can be adjusted, and the pressure of the refrigerant added into the compression module 2 can be adjusted.

[0028] As an optional implementation of the embodiment of the present invention, an oil separator is connected to the pipeline on the outlet side of the compression module 1 and the pipeline on the outlet side of the compression module 2. Figure 1 A first vertical oil separator 2 is provided on the pipeline at the outlet side of compression module 1, and a second vertical oil separator 3 is provided on the pipeline at the outlet side of compression module 2. The function of the oil separator is to separate the lubricating oil in the high-pressure steam discharged from the refrigeration compressor to ensure the safe and efficient operation of the device.

[0029] As an optional implementation mode of the embodiment of the present invention, the compression refrigeration system further includes an evaporator and a condenser 5, and the evaporator and the condenser 5 are both shell and tube heat exchangers.

[0030] Embodiment 1:

[0031] See also Figure 1 A compression refrigeration system, a first screw compressor 1 and a second screw compressor 17 are connected in parallel, and the two share a first vertical oil separator 2. The refrigerant comes out of the return air port of the first vertical oil separator 2 and merges with the high-pressure and medium-temperature refrigerant gas (from the liquid storage tank 12) of the branch to enter the third screw compressor 4. The exhaust port of the third screw compressor 4 is connected to the second vertical oil separator 3. The refrigerant passes through the second vertical oil separator 3 and enters the condenser 5 (shell and tube condenser), and flows to the liquid storage tank 12 through the economizer 6, the regulating valve 8 and the stop valve 11. In the liquid storage tank 12, a safety valve 10 is installed on the top, and the liquid refrigerant outlet is connected to the evaporator 15 (shell and tube evaporator) inlet, and the stop valve 13 and the second electronic expansion valve 14 are installed between the two. The gaseous refrigerant in the liquid storage tank 12 passes through the drying filter 9 and the first electronic expansion valve 7 and enters the third screw compressor 4. The refrigerant in the evaporator 15 flows to the first screw compressor 1 and the second screw compressor 17 after passing through the drying filter 16.

[0032] Embodiment 2:

[0033] A water chiller comprises the compression refrigeration system described in Example 1. The chilled water in the water chiller is mainly low-temperature ethylene glycol or brine with an outlet temperature below 0°C.

[0034] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A compression refrigeration system, characterized in that: It includes compression module 1 and compression module 2, wherein: The compression module 1 and the compression module 2 are connected in series and the refrigerant discharged from the compression module 1 can flow to the compression module 2, the compression module 1 includes at least two compressors and the compressors in the compression module 1 are connected in parallel; The compression refrigeration system further comprises a liquid accumulator (12), a gas discharge port of the liquid accumulator (12) being connected to the pipeline between the compression module 1 and the compression module 2 via a pressure compensation pipeline; The pipeline on the outlet side of the compression module 1 and the pipeline on the outlet side of the compression module 2 are both connected with an oil separator.

2. The compression refrigeration system according to claim 1, characterized in that: The number of compressors in the compression module 2 is one; or, the number of compressors in the compression module 2 is more than two, and the compressors in the compression module 2 are connected in parallel.

3. The compression refrigeration system according to claim 1, characterized in that: All the compressors in the compression module 1 are the same; all the compressors in the compression module 2 are the same; The compressor in the compression module one is the same as or different from the compressor in the compression module two.

4. The compression refrigeration system according to claim 1, characterized in that: The compressors in the compression module 1 are all screw compressors; the compressors in the compression module 2 are all screw compressors.

5. The compression refrigeration system according to any one of claims 1 to 4, characterized in that: The compression refrigeration system also includes an evaporator (15), and the refrigerant passing through the evaporator (15) can be directly discharged to the compression module one, or the refrigerant passing through the evaporator (15) flows to a drying filter and then can be discharged to the compression module one.

6. The compression refrigeration system according to claim 1, characterized in that: An expansion valve is arranged on the pressure-compensating pipeline.

7. The compression refrigeration system according to claim 1, characterized in that: The compression refrigeration system further comprises an evaporator (15) and a condenser (5), wherein the evaporator (15) and the condenser (5) are both shell and tube heat exchangers.

8. A chiller, characterized in that: A compression refrigeration system comprising any one of claims 1-7.

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