Parallel refrigerating system for cooling lubricating oil by using economizer

Abstract

The utility model provides a parallel refrigerating system utilizing an economizer to cool lubricating oil, a horizontal liquid accumulator (4) is connected with a compressor economizer assembly (5), and an outlet at the lower end of an oil separator (2) is divided into a high-temperature oil pipe (23) and a first inlet pipe (61) of a plate heat exchanger through a first oil tee joint (222). A first inlet pipe (61) of the plate heat exchanger and a second outlet pipe (53) of an economizer of the compressor economizer assembly (5) are connected with two inlets in the right side of the oil cooling assembly (6) respectively, a first outlet pipe (63) of the plate heat exchanger of the oil cooling assembly (6) and a high-temperature oil pipe (23) are connected with an inlet of a second oil tee joint (231) respectively, and an outlet of the second oil tee joint (231) is connected with the oil supply collecting pipe (14). According to the system, through combined use of the compressor economizer assembly (5) and the oil cooling assembly (6), lubricating oil of the refrigerating system can be cooled, the refrigerating system is simplified, and operation is easy and convenient.

Description

Technical Field

[0001] The utility model relates to the technical field of parallel refrigeration systems, in particular to a parallel refrigeration system utilizing an economizer to cool lubricating oil. Background Art

[0002] A parallel compressor refrigeration system is a system in which multiple refrigeration compressors are centrally installed in parallel on the unit's chassis, facilitating centralized control, transportation, and operational maintenance. It is a commonly used refrigeration unit system for large or extra-large cold storage facilities, and is widely used in various applications, including chemical, mining, large and medium-sized test environments, cold storage, food processing, and aquatic product processing. However, when a parallel compressor refrigeration system is currently in operation, the mixed medium of high-temperature refrigerant and lubricating oil discharged from the multiple refrigeration compressors enters the oil separator together. After the high-temperature lubricating oil and high-temperature gaseous refrigerant are separated in the oil separator, the high-temperature lubricating oil is directly returned to the individual compressors of the parallel compressor refrigeration system, or the high-temperature lubricating oil is cooled by a water-cooled oil cooler or an air-cooled oil cooler and then returned to the individual compressors. If high-temperature lubricating oil directly enters the parallel compressor, it will easily cause the exhaust temperature of the parallel compressor to be too high, which will directly affect the refrigeration efficiency of the parallel compressor refrigeration system. If a water-cooled oil cooler or an air-cooled oil cooler is used to cool the lubricating oil, the structural complexity and control difficulty of the parallel compressor refrigeration system will be increased, and the temperature of the lubricating oil will be difficult to control, which will also affect the efficient operation of the parallel compressor refrigeration system.

[0003] In addition, during the operation of the parallel compressor refrigeration system, in order to reduce the refrigerant temperature at the air inlet of the parallel compressors and improve the compression efficiency of each compressor, the lubricating oil temperature is usually reduced, and the cooled lubricating oil and the gaseous refrigerant in the return air manifold are introduced into the suction port of the parallel compressor together. However, this method easily leads to a small amount of lubricating oil flow entering the suction port of the compressor, and the effect of cooling the high-temperature gaseous refrigerant by the low-temperature lubricating oil is not significant; and when the liquid lubricating oil and the gaseous refrigerant are mixed and contacted, the contact area for heat exchange between the two is limited, resulting in an insignificant cooling effect on the gaseous refrigerant, causing the parallel compressors to be in a low-efficiency operating state, which directly affects the service life of the parallel compressor refrigeration system.

[0004] Currently, in order to reduce the refrigerant temperature entering the air inlets of each compressor in a parallel compressor refrigeration system, a refrigerant cooling method with an economizer as the core component is usually adopted. Therefore, on the basis of effectively reducing the refrigerant temperature entering the air inlets of each compressor in the parallel compressor refrigeration system, by adding a component with a simple structure and convenient operation, the purpose of reducing the refrigerant temperature at each compressor inlet is achieved, and at the same time, the temperature of the lubricating oil flowing back to each compressor is effectively reduced, ensuring that each compressor in the parallel compressor refrigeration system is in an efficient operating state, which can effectively extend the service life of the entire refrigeration system. There is an urgent need for a parallel refrigeration system that uses an economizer to cool the lubricating oil. Utility Model Content

[0005] In response to the above technical defects, in order to solve the technical problem of excessively high refrigerant and lubricating oil temperatures at the air inlets of each compressor in the existing parallel compressor refrigeration system, the utility model proposes a parallel refrigeration system that uses an economizer to cool the lubricating oil by adding a plate heat exchanger component.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a parallel refrigeration system using an economizer to cool lubricating oil, comprising a refrigeration compressor, an oil separator, an external condenser, a horizontal liquid reservoir, a compressor economizer assembly, an oil cooling assembly and a gas-liquid separator, wherein several refrigeration compressors are centrally installed on the rack of the unit in a parallel manner, the outlets of the several refrigeration compressors are respectively connected to the exhaust manifolds through pipes, the other end of the exhaust manifold is connected to the inlet of the oil separator, the top outlet of the oil separator is connected to the inlet of the external condenser through the oil separation exhaust pipe, the outlet of the external condenser is connected to the inlet of the horizontal liquid reservoir through the condenser drain pipe, the bottom outlet of the horizontal liquid reservoir is connected to the inlet of the compressor economizer assembly through the liquid reservoir drain pipe, the second outlet pipe of the economizer and the first outlet pipe of the economizer are respectively connected to the outlet of the compressor economizer assembly, the lower outlet of the oil separator is The inlets of the oil filters are connected through oil distribution and drain pipes. The outlet pipe of the oil filter is divided into a high-temperature oil pipe and a first plate exchanger inlet pipe through an oil tee A. The first plate exchanger inlet pipe and the second economizer outlet pipe of the compressor economizer assembly are respectively connected to the two inlets on the right side of the oil cooling assembly. The first plate exchanger outlet pipe and the high-temperature oil pipe of the oil cooling assembly are respectively connected to the inlet of the oil tee B. The outlet of the oil tee B is connected to the oil supply manifold. The lubricating oil inlets of several refrigeration compressors are respectively connected to the oil supply manifold through the oil supply branch pipe. The second plate exchanger outlet pipe of the oil cooling assembly is connected to the air supply manifold. The air supply ports of several refrigeration compressors are respectively connected to the air supply manifold through the air supply branch pipe. The evaporator is connected to the inlet of the gas-liquid separator through the evaporator return air pipe. The outlet of the gas-liquid separator is connected to the return air manifold through the intake filter. The return air ports of several refrigeration compressors are respectively connected to the return air manifold through the return air branch pipe.

[0007] Furthermore, the compressor economizer assembly includes a drying filter, a sight glass A, a solenoid valve, a sight glass B, a thermal expansion valve, an economizer, a temperature sensing package and a liquid supply ball valve. The liquid reservoir discharge pipe is connected to the first inlet pipe of the economizer in sequence through the drying filter, the stop valve and the sight glass A. The drying filter is arranged in a horizontal direction. The first inlet pipe of the economizer is connected to the upper right inlet of the economizer. One end of the second inlet pipe of the economizer is connected to the first inlet pipe of the economizer and the connection point is behind the sight glass A. The other end of the second inlet pipe of the economizer is connected to the lower right inlet of the economizer. The solenoid valve, the sight glass B and the thermal expansion valve are installed in sequence along the flow direction of the medium in the second inlet pipe of the economizer. The lower left outlet of the economizer is connected to the first outlet pipe of the economizer through the liquid supply ball valve. The other end of the first outlet pipe of the economizer is connected to the evaporator. The second outlet pipe of the economizer is connected to the upper left outlet of the economizer. The temperature sensing package is installed on the second outlet pipe of the economizer and the temperature sensing package is connected to the thermal expansion valve through a connecting line.

[0008] Furthermore, the oil cooling assembly includes a plate heat exchanger and a stop valve, the first inlet pipe of the plate heat exchanger is connected to the upper right inlet of the plate heat exchanger through the stop valve, the second outlet pipe of the economizer is connected to the lower right inlet of the plate heat exchanger through the stop valve, the upper left outlet of the plate heat exchanger is connected to the second outlet pipe of the plate heat exchanger through the stop valve, and the lower left outlet of the plate heat exchanger is connected to the first outlet pipe of the plate heat exchanger through the stop valve, wherein the first inlet pipe of the plate heat exchanger is connected to the first outlet pipe of the plate heat exchanger through the plate heat exchanger, and the second outlet pipe of the economizer is connected to the second outlet pipe of the plate heat exchanger through the plate heat exchanger.

[0009] Furthermore, the part where the oil separator is connected to the oil exhaust pipe is in a vertical state, the part where the oil exhaust pipe is connected to the external condenser is in a horizontal state, a one-way valve is provided at the position of the oil exhaust pipe near the outlet of the oil separator, a stop valve is provided at the position of the oil exhaust pipe near the inlet of the external condenser, and a pressure gauge and a drain valve are provided at the horizontal section where the oil exhaust pipe is connected to the external condenser, wherein the drain valve is installed between the pressure gauge and the stop valve at the inlet of the external condenser, and the drain valve is in a normally closed state.

[0010] Furthermore, the horizontal liquid reservoir is arranged on the frame of the unit or outside the unit, the horizontal liquid reservoir is in a horizontal installation state, and the liquid reservoir safety valve is arranged on the top of the horizontal liquid reservoir.

[0011] Furthermore, the solenoid valve start-stop control line is connected to the programmable logic controller PLC of the system control component, and the solenoid valve start-stop control line is connected to the analog output end of the programmable logic controller PLC.

[0012] Compared with the prior art, the parallel refrigeration system using an economizer to cool the lubricating oil, by adding an oil cooling component with a plate heat exchanger as the core and utilizing the low-temperature gaseous circulating working fluid provided by the compressor economizer component, can not only provide low-temperature gaseous circulating working fluid for the return air of the parallel refrigeration compressors, thereby avoiding the phenomenon of excessive exhaust temperature caused by excessively high inlet temperature of the refrigeration compressors, but also can cool the lubricating oil, effectively reduce the temperature of the lubricating oil returning to each compressor, ensure that the parallel refrigeration compressors are all in an efficient operating state, and effectively extend the service life of the entire refrigeration system. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the overall system diagram of the utility model;

[0014] Figure 2 This is a system diagram of the compressor economizer assembly of the present utility model;

[0015] Figure 3 This is a system diagram of the oil cooling assembly of the present utility model.

[0016] The following are marked in the figure: 1: refrigeration compressor; 11: return air manifold; 12: return air branch pipe; 13: exhaust manifold; 14: oil supply manifold; 15: oil supply branch pipe; 16: air supply manifold; 17: air supply branch pipe; 2: oil separator; 21: oil separator exhaust pipe; 211: one-way valve; 212: pressure gauge; 213: drain valve; 22: oil separator drain pipe; 221: oil filter; 222: oil tee A; 23: high-temperature oil pipe; 231: oil tee B; 3: external condenser; 31: condenser drain pipe; 4: horizontal liquid receiver; 41: liquid receiver drain pipe; 411: dry filter; 4 12: Sight glass A; 42: Liquid storage safety valve; 5: Compressor economizer assembly; 51: Economizer first inlet pipe; 52: Economizer second inlet pipe; 521: Solenoid valve; 522: Sight glass B; 523: Thermal expansion valve; 53: Economizer second outlet pipe; 531: Temperature sensing package; 54: Economizer first outlet pipe; 541: Liquid supply ball valve; 55: Economizer; 6: Oil cooling assembly; 61: Plate heat exchanger first inlet pipe; 62: Plate heat exchanger second outlet pipe; 63: Plate heat exchanger first outlet pipe; 64: Plate heat exchanger; 7: Gas-liquid separator; 71: Evaporator return air pipe; 72: Intake filter. DETAILED DESCRIPTION

[0017] In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "inside", "outside", "front end", "rear end", "two ends", "one end", "the other end", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as a limitation on the present invention.

[0018] In order to make the technical problems, technical solutions and implementation effects to be solved by the present invention clearer, the following is a summary of the technical problems, technical solutions and implementation effects to be solved by the present invention. Figure 1 、 2 3, an embodiment of the present invention is further described:

[0019] Reference Attachment Figure 1 , attached Figure 2 , attached Figure 3The utility model discloses a parallel refrigeration system using an economizer to cool lubricating oil, comprising a refrigeration compressor 1, an oil separator 2, an external condenser 3, a horizontal liquid reservoir 4, a compressor economizer assembly 5, an oil cooling assembly 6 and a gas-liquid separator 7, wherein several refrigeration compressors 1 are centrally installed on the rack of the unit in a parallel manner, and the outlets of the several refrigeration compressors 1 are respectively connected to the exhaust manifold 13 through pipes, the other end of the exhaust manifold 13 is connected to the inlet of the oil separator 2, the top outlet of the oil separator 2 is connected to the inlet of the external condenser 3 through an oil separation exhaust pipe 21, the outlet of the external condenser 3 is connected to the inlet of the horizontal liquid reservoir 4 through a condenser drain pipe 31, the bottom outlet of the horizontal liquid reservoir 4 is connected to the inlet of the compressor economizer assembly 5 through a liquid reservoir drain pipe 41, the second economizer outlet pipe 53 and the first economizer outlet pipe 54 are respectively connected to the outlet of the compressor economizer assembly 5, and the lower end outlet of the oil separator 2 is connected to the inlet of the oil filter 221 through an oil separation drain pipe 22 Then, the outlet pipe of the oil filter 221 is divided into a high-temperature oil pipe 23 and a first plate-exchanger inlet pipe 61 through an oil tee 222. The first plate-exchanger inlet pipe 61 and the second economizer outlet pipe 53 of the compressor economizer assembly 5 are respectively connected to the two right inlets of the oil cooling assembly 6. The first plate-exchanger outlet pipe 63 and the high-temperature oil pipe 23 of the oil cooling assembly 6 are respectively connected to the inlet of the oil tee 231. The outlet of the oil tee 231 is connected to the oil supply manifold 14. The lubricating oil inlets of several refrigeration compressors 1 are respectively connected through The oil supply branch pipe 15 is connected to the oil supply manifold 14, the second outlet pipe 62 of the plate exchanger of the oil cooling assembly 6 is connected to the air supply manifold 16, and the air supply ports of several refrigeration compressors 1 are respectively connected to the air supply manifold 16 through the air supply branch pipes 17. The evaporator is connected to the inlet of the gas-liquid separator 7 through the evaporator return air pipe 71, and the outlet of the gas-liquid separator 7 is connected to the return air manifold 11 through the intake filter 72. The return air ports of several refrigeration compressors 1 are respectively connected to the return air manifold 11 through the return air branch pipes 12.

[0020] As a preferred embodiment, the compressor economizer assembly 5 includes a drying filter 411, a sight glass A 412, a solenoid valve 521, a sight glass B 522, a thermal expansion valve 523, an economizer 55, a temperature sensing package 531 and a liquid supply ball valve 541. The liquid reservoir pipe 41 is connected to the first economizer inlet pipe 51 through the drying filter 411, the stop valve and the sight glass A 412 in sequence. The drying filter 411 is set in a horizontal direction. The first economizer inlet pipe 51 is connected to the upper right side inlet of the economizer 55. One end of the second economizer inlet pipe 52 is connected to the first economizer inlet pipe 51 and the connection point is at the sight glass. After the mirror A 412, the other end of the second inlet pipe 52 of the economizer is connected to the lower right inlet of the economizer 55. The solenoid valve 521, the sight glass B 522 and the thermal expansion valve 523 are installed in sequence along the flow direction of the medium in the second inlet pipe 52 of the economizer. The lower left outlet of the economizer 55 is connected to the first outlet pipe 54 of the economizer through the liquid supply ball valve 541. The other end of the first outlet pipe 54 of the economizer is connected to the evaporator. The second outlet pipe 53 of the economizer is connected to the upper left outlet of the economizer 55. The temperature sensing package 531 is installed on the second outlet pipe 53 of the economizer and the temperature sensing package 531 is connected to the thermal expansion valve 523 through a connecting line.

[0021] As a preferred embodiment, the medium entering the compressor economizer assembly 5 is dried by the drying filter 411, and at the same time, impurities in the medium can be filtered out to avoid blockage of the refrigeration cycle system; the flow of the medium entering the compressor economizer assembly 5 can be observed through the sight glass A 412, and it can also be detected whether the drying filter 411 is blocked due to long-term use; the flow of the medium entering the thermal expansion valve 523 can be observed through the sight glass B 522; the temperature sensor 531 installed on the second outlet pipe 53 of the economizer can accurately detect the temperature of the medium in the second outlet pipe 53 of the economizer, and then the opening of the thermal expansion valve 523 can be controlled, and the temperature of the medium in the second outlet pipe 53 of the economizer can be adjusted in time to provide sufficient cooling capacity for the oil cooling assembly 6.

[0022] As a preferred embodiment, the oil cooling assembly 6 includes a plate heat exchanger 64 and a stop valve, the first plate heat exchanger inlet pipe 61 is connected to the upper right inlet of the plate heat exchanger 64 through the stop valve, the second economizer outlet pipe 53 is connected to the lower right inlet of the plate heat exchanger 64 through the stop valve, the upper left outlet of the plate heat exchanger 64 is connected to the second plate heat exchanger outlet pipe 62 through the stop valve, and the lower left outlet of the plate heat exchanger 64 is connected to the first plate heat exchanger outlet pipe 63 through the stop valve, wherein the first plate heat exchanger inlet pipe 61 is connected to the first plate heat exchanger outlet pipe 63 through the plate heat exchanger 64, the second economizer outlet pipe 53 is connected to the second plate heat exchanger outlet pipe 62 through the plate heat exchanger 64, and the four stop valves on the left and right sides of the plate heat exchanger 64 are in a normally open state.

[0023] As a preferred embodiment, the part of the oil separator 2 connected with the oil separation exhaust pipe 21 is in a vertical state, the part of the oil separation exhaust pipe 21 connected with the external condenser 3 is in a horizontal state, the one-way valve 211 is arranged at the position close to the outlet of the oil separator 2, when the medium in the oil separation exhaust pipe 21 flows forward, the one-way valve 211 can only pass forward and cannot flow reversely, thereby avoiding the medium in the oil separation exhaust pipe 21 flowing reversely into the oil separator 2, the stop valve is arranged at the position close to the inlet of the external condenser 3, the pressure gauge 212 and the emptying valve 213 are arranged at the horizontal section of the oil separation exhaust pipe 21 connected with the external condenser 3, the emptying valve 213 is installed between the pressure gauge 212 and the stop valve at the inlet of the external condenser 3, the emptying valve 213 is in a normally closed state, the pressure change of the medium in the horizontal pipe of the oil separation exhaust pipe 21 connected with the external condenser 3 can be detected through the pressure gauge 212, the gaseous circulating medium generated by the external condenser 3 and other systems during the long-time shutdown of the refrigeration system can be discharged through the emptying valve 213, thereby avoiding the phenomenon that the circulating medium cannot normally enter the external condenser 3 due to the excessive pressure in the refrigeration system after the refrigeration system is started.

[0024] As a preferred embodiment, the horizontal liquid reservoir 4 is arranged on the rack of the unit or outside the unit, the horizontal liquid reservoir 4 is in a horizontal installation state, and the safety valve 42 of the horizontal liquid reservoir 4 is arranged at the top of the horizontal liquid reservoir 4.

[0025] As a preferred embodiment, the electromagnetic valve 521 start-stop control line is connected to the programmable logic controller PLC of the system control assembly, the electromagnetic valve 521 start-stop control line is connected to the analog output end of the programmable logic controller PLC, when the system is in a shutdown state, the programmable logic controller PLC closes the electromagnetic valve 521, when the system is in a normal working state, the stop valves on the left and right sides of the plate heat exchanger 64 are in an open state, the oil tee nut A 222 and the oil tee nut B 231 are also in an open state, when the temperature of the lubricating oil entering the refrigeration compressor 1 is lower than the set value or the exhaust temperature is lower than the set value, the programmable logic controller PLC still controls the electromagnetic valve 521 to be in a closed state, but when the temperature of the lubricating oil entering the refrigeration compressor 1 is higher than the set value or the exhaust temperature is higher than the set value, the programmable logic controller PLC controls the electromagnetic valve 521 to be opened, the low-temperature gas passing through the compressor economizer assembly 5 enters the oil cooling assembly 6, thereby not only realizing the cooling of the lubricating oil, but also realizing the return of the low-temperature circulating working medium to the gas inlet of the refrigeration compressor 1.

[0026] As a preferred embodiment, a parallel refrigeration system using an economizer to cool the lubricating oil is described. When the parallel refrigeration system is started, the programmable logic controller PLC controls the solenoid valve 521 of the compressor economizer assembly 5 to be in a closed state. After passing through the oil separator 2, the high-temperature gaseous circulating working medium enters the external condenser 3 through the oil separation exhaust pipe 21 and is converted into a liquid circulating working medium, and enters the horizontal liquid reservoir 4 through the condenser discharge pipe 31. The liquid circulating working medium in the horizontal liquid reservoir 4 passes through the liquid reservoir discharge pipe 41 and the compressor economizer assembly 5 and enters the first outlet pipe 54 of the economizer, providing liquid circulating working medium for the evaporator. The lubricating oil after passing through the oil separator 2 passes through the oil separation discharge pipe 22, the oil filter 221 and the oil tee 222, and then enters the oil supply manifold 14 along the high-temperature oil pipe 23 and the oil cooling assembly 6, and provides each refrigeration compressor 1. Supply lubricating oil. At this time, since the solenoid valve 521 is in a closed state, the lubricating oil passes through the oil cooling component 6 but is not cooled. However, when the parallel refrigeration system detects that the temperature of the lubricating oil flowing back to each refrigeration compressor 1 is higher than the set value or the exhaust temperature is higher than the set value, the programmable logic controller PLC controls the solenoid valve 521 of the compressor economizer component 5 to open. After the liquid circulating medium enters the compressor economizer component 5, it is transformed into a low-temperature gaseous circulating medium through the action of the thermal expansion valve 523. The low-temperature gaseous circulating medium and the high-temperature lubricating oil are heat-exchanged in the oil cooling component 6, so that the high-temperature lubricating oil is converted into low-temperature lubricating oil. The low-temperature lubricating oil and the high-temperature lubricating oil in the high-temperature oil pipe 23 are fully mixed after passing through the oil tee 231, and enter the oil supply manifold 14 together to provide lubricating oil for each refrigeration compressor 1, thereby cooling the lubricating oil.

[0027] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A parallel refrigeration system utilizing an economizer to cool lubricating oil, comprising a refrigeration compressor (1), an oil separator (2), an external condenser (3), a horizontal liquid receiver (4), a compressor economizer assembly (5), an oil cooling assembly (6), and a gas-liquid separator (7), characterized in that: The lower end outlet of the oil separator (2) is connected to the inlet of the oil filter (221) through an oil separation drain pipe (22). The outlet pipe of the oil filter (221) is divided into a high-temperature oil pipe (23) and a first plate exchanger inlet pipe (61) through an oil tee (222). The first plate exchanger inlet pipe (61) and the second economizer outlet pipe (53) of the compressor economizer assembly (5) are respectively connected to the two right inlets of the oil cooling assembly (6). The first plate exchanger outlet pipe (63) and the second economizer outlet pipe (53) of the oil cooling assembly (6) are respectively connected to the two right inlets of the oil cooling assembly (6). The high-temperature oil pipe (23) is connected to the inlet of the oil tee (231), the outlet of the oil tee (231) is connected to the oil supply manifold (14), the lubricating oil inlets of the plurality of refrigeration compressors (1) are connected to the oil supply manifold (14) through the oil supply branch pipe (15), the second outlet pipe (62) of the plate exchanger of the oil cooling assembly (6) is connected to the air supply manifold (16), and the air supply ports of the plurality of refrigeration compressors (1) are connected to the air supply manifold (16) through the air supply branch pipe (17).

2. The parallel refrigeration system using an economizer to cool lubricating oil according to claim 1, characterized in that: The compressor economizer assembly (5) includes a drying filter (411), a sight glass A (412), a solenoid valve (521), a sight glass B (522), a thermal expansion valve (523), an economizer (55), a temperature sensing package (531) and a liquid supply ball valve (541). The liquid storage pipe (41) is connected to the first inlet pipe (51) of the economizer through the drying filter (411), the stop valve and the sight glass A (412) in sequence. The drying filter (411) is set in a horizontal direction. The first inlet pipe (51) of the economizer is connected to the upper right side inlet of the economizer (55). One end of the second inlet pipe (52) of the economizer is connected to the first inlet pipe (51) of the economizer and the connection point is at the sight glass A (41 2), the other end of the second inlet pipe (52) of the economizer is connected to the lower right inlet of the economizer (55), and the solenoid valve (521), sight glass B (522) and thermal expansion valve (523) are installed in sequence along the flow direction of the medium in the second inlet pipe (52) of the economizer. The lower left outlet of the economizer (55) is connected to the first outlet pipe (54) of the economizer through the liquid supply ball valve (541), and the other end of the first outlet pipe (54) of the economizer is connected to the evaporator. The second outlet pipe (53) of the economizer is connected to the upper left outlet of the economizer (55). The temperature sensing package (531) is installed on the second outlet pipe (53) of the economizer and the temperature sensing package (531) is connected to the thermal expansion valve (523) through a connecting line.

3. The parallel refrigeration system using an economizer to cool lubricating oil according to claim 1, characterized in that: The oil cooling assembly (6) includes a plate heat exchanger (64) and a stop valve, wherein the first inlet pipe (61) of the plate heat exchanger is connected to the upper right inlet of the plate heat exchanger (64) through the stop valve, the second outlet pipe (53) of the economizer is connected to the lower right inlet of the plate heat exchanger (64) through the stop valve, the upper left outlet of the plate heat exchanger (64) is connected to the second outlet pipe (62) of the plate heat exchanger through the stop valve, and the lower left outlet of the plate heat exchanger (64) is connected to the first outlet pipe (63) of the plate heat exchanger through the stop valve, wherein the first inlet pipe (61) of the plate heat exchanger is connected to the first outlet pipe (63) of the plate heat exchanger through the plate heat exchanger (64), and the second outlet pipe (53) of the economizer is connected to the second outlet pipe (62) of the plate heat exchanger through the plate heat exchanger (64).

4. The parallel refrigeration system using an economizer to cool lubricating oil according to claim 1, characterized in that: The portion where the oil separator (2) is connected to the oil exhaust pipe (21) is in a vertical state, and the portion where the oil exhaust pipe (21) is connected to the external condenser (3) is in a horizontal state. A one-way valve (211) is provided at a position of the oil exhaust pipe (21) close to the outlet of the oil separator (2), and a stop valve is provided at a position of the oil exhaust pipe (21) close to the inlet of the external condenser (3). A pressure gauge (212) and a drain valve (213) are provided at the horizontal section where the oil exhaust pipe (21) is connected to the external condenser (3), wherein the drain valve (213) is installed between the pressure gauge (212) and the stop valve at the inlet of the external condenser (3), and the drain valve (213) is in a normally closed state.

5. The parallel refrigeration system using an economizer to cool lubricating oil according to claim 1, characterized in that: The horizontal liquid reservoir (4) is arranged on the frame of the unit or outside the unit, the horizontal liquid reservoir (4) is in a horizontal installation state, and the liquid reservoir safety valve (42) is arranged on the top of the horizontal liquid reservoir (4).

6. A parallel refrigeration system using an economizer to cool lubricating oil according to claim 1 or 2, characterized in that: The start / stop control line of the solenoid valve (521) is connected to the programmable logic controller (PLC) of the system control component, and the start / stop control line of the solenoid valve (521) is connected to the analog output terminal of the programmable logic controller (PLC).

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