System for separating lubricating oil on low-pressure side of refrigerating system in working medium heat exchange mode

Abstract

The utility model relates to the technical field of refrigerating systems, in particular to a system for separating lubricating oil on the low-pressure side of a refrigerating system in a working medium heat exchange mode, which comprises a heat exchanger and an oil collector which are arranged up and down, and an oil collecting pipe is communicated between the bottom of the heat exchanger and the top of the oil collector. The top of the heat exchanger is communicated with an oil taking pipe, the oil taking pipe is provided with an oil taking pipe valve group FZ-1, the left side of the heat exchanger is communicated with a hot air pipeline, the hot air pipeline is provided with a hot air pipe valve group FZ-3, and the right side of the heat exchanger is communicated with a gas-liquid separator gas inlet pipe. The heat exchanger and the oil collector are combined for oil-liquid separation, so that the separation efficiency of lubricating oil is improved to the maximum extent, the energy consumption is reduced, and the running safety of the compressor during oil return is considered.

Description

Technical Field

[0001] The utility model belongs to the technical field of refrigeration systems, and in particular relates to a system that separates lubricating oil on the low-pressure side of a refrigeration system by using a working medium heat exchange method. Background Art

[0002] At present, in the two-stage cascade refrigeration system of fluorine / CO2 and ammonia / CO2 (refrigerant), as the time of the refrigeration system is prolonged, the refrigeration oil entering the low-pressure side will accumulate more and more. A large amount of lubricating oil participates in the circulation on the low-pressure side and accumulates on the inner surface of the evaporator to form an oil film, which reduces the heat exchange efficiency of the heat exchanger. The traditional method of directly returning oil from the oil intake port of the low-pressure circulation barrel to the suction port of the compressor, due to the mixing and flow problems of the refrigerant and lubricating oil in the gas-liquid separator, most of the liquid returned to the compressor is refrigerant, which brings certain hazards to the safe operation of the compressor.

[0003] There are usually three main ways to separate lubricating oil from refrigerant. The first is an external oil collector, in which a mixed liquid containing lubricating oil and refrigerant flows into the external oil collector from the liquid (oil) inlet on the low-pressure side by gravity. The oil collector is not insulated and the refrigerant in the oil collector is evaporated by the heat of nature, and the remaining lubricating oil is discharged from the system. This method is extremely inefficient. The second is automatic oil return, in which an electric heating device and an electric control system are added to the external oil collector. The refrigerant is evaporated by consuming electric energy, and the separated oil is prevented from entering the outside or returned to the compressor suction port. This method consumes a lot of electric energy and will bring certain safety hazards. The third method is that the oil inlet of the gas-liquid separator directly returns the oil to the compressor suction port, and the mixed liquid is separated by the operation of the compressor. This is extremely inefficient and will cause safety hazards in the operation of the compressor. Utility Model Content

[0004] In view of the shortcomings of the prior art, the purpose of the utility model is to provide a system that separates the lubricating oil on the low-pressure side of a refrigeration system by means of working fluid heat exchange, so as to solve the problems that the efficiency of oil separation such as natural volatilization using an external oil collector is extremely low and cannot meet system requirements; the use of an external oil collector to add an electric heating device requires a large amount of electric energy to be wasted, and if the electric heating fails, it will bring certain safety hazards; the method of directly returning the mixed liquid to the compressor suction port has extremely low efficiency in oil separation and will cause safety hazards in the operation of the compressor.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a system for separating lubricating oil on the low-pressure side of a refrigeration system by means of working medium heat exchange, comprising a heat exchanger and an oil collector arranged up and down, wherein an oil collecting pipe is provided between the bottom of the heat exchanger and the top of the oil collector;

[0006] The top of the heat exchanger is connected to an oil extraction pipe, on which an oil extraction pipe valve group FZ-1 is provided, the left side of the heat exchanger is connected to a hot gas pipeline, on which a hot gas pipeline valve group FZ-3 is provided, and the right side of the heat exchanger is connected to an air inlet pipe of a gas-liquid separator;

[0007] Among them, a liquid level controller is arranged on the oil collector, an oil return pipe is arranged at the bottom of the oil collector, the output end of the oil return pipe is connected to the air intake port of the compressor, and an oil return pipe valve group FZ-4 is arranged on the oil return pipe.

[0008] Preferably, one side of the top of the heat exchanger is also connected to a low-pressure balancing pipe, and a low-pressure balancing pipe valve group FZ-2 is provided on the low-pressure balancing pipe.

[0009] Preferably, a sewage outlet is provided at the bottom of the oil collector.

[0010] Compared with the prior art, the beneficial effects of the utility model are:

[0011] 1. The utility model adopts a combination of a heat exchanger and an oil collector to separate oil and liquid, which can maximize the separation efficiency of lubricating oil while reducing energy consumption and taking into account the safety of compressor operation during oil return.

[0012] 2. The utility model innovatively uses the waste heat of high-pressure exhaust gas from the low-temperature system to heat the mixed liquid of refrigerant and oil taken out from the low-pressure side, which is convenient for safely and efficiently separating the lubricating oil. After a certain amount of lubricating oil is separated, it is discharged to the outside or returned to the suction port of the compressor, solving the safety hazard problem caused by liquid return in the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the principle diagram of the working medium heat exchange refrigeration oil return structure of the utility model.

[0014] In the figure: 1. heat exchanger; 101. oil intake pipe; 102. oil intake pipe valve group FZ-1; 103. hot gas pipeline; 104. hot gas pipe valve group FZ-3; 105. low-pressure balance pipe; 106. low-pressure balance pipe valve group FZ-2; 107. gas-liquid separator air inlet pipe; 2. oil collector; 201. liquid level controller; 202. oil return pipe; 203. compressor suction port; 204. oil return pipe valve group FZ-4; 205. sewage outlet; 3. oil collecting pipe. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below through embodiments and in combination with the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0016] Refer to the following Figure 1 A system for separating lubricating oil on the low-pressure side of a refrigeration system by using working medium heat exchange is described in an embodiment of the present application.

[0017] A system for separating lubricating oil on the low-pressure side of a refrigeration system by heat exchange of working fluids, comprising a heat exchanger 1 and an oil collector 2 arranged up and down, wherein an oil collecting pipe 3 is provided between the bottom of the heat exchanger 1 and the top of the oil collector 2;

[0018] The top of the heat exchanger 1 is connected to an oil extraction pipe 101, on which an oil extraction pipe valve group FZ-1 is provided; the left side of the heat exchanger 1 is connected to a hot gas pipeline 103, on which a hot gas pipe valve group FZ-3 is provided; the right side of the heat exchanger 1 is connected to a gas-liquid separator air inlet pipe 107;

[0019] Among them, a liquid level controller 201 is arranged on the oil collector 2, and the liquid level controller 201 uses the LS101 liquid level controller. A return oil pipe 202 is arranged at the bottom of the oil collector 2, and the output end of the return oil pipe 202 is connected to the compressor suction port 203. The return oil pipe 202 is provided with an oil return pipe valve group FZ-4.

[0020] Furthermore, a low-pressure balancing pipe 105 is also connected to one side of the top of the heat exchanger 1 , and a low-pressure balancing pipe valve group FZ- 2 is provided on the low-pressure balancing pipe 105 .

[0021] Automatic operation is achieved through the control of the solenoid valve group arranged as above, and the system is simple, the control is simple, and the operation stability is high.

[0022] In a further embodiment, a sewage outlet 205 is provided at the bottom of the oil collector 2 .

[0023] In a further embodiment, the system also includes other auxiliary pipelines, which are prior art and are not described in detail.

[0024] Combined with the above embodiments, the working principle and specific working process of a system of the present application that uses working medium heat exchange to separate lubricating oil on the low-pressure side of a refrigeration system are described:

[0025] The oil (mixture of lubricating oil and refrigerant) enters the shell side of heat exchanger 1, and the hot gas on the low-pressure side enters the tube side of heat exchanger 1. The heat of the hot gas vaporizes the refrigerant in the oil and returns to the gas-liquid separator through the gas-liquid separator inlet pipe 107, while the lubricating oil that cannot be vaporized flows into the oil collector 2 below through the oil collecting pipe 3, thereby separating the refrigerant and lubricating oil. When a certain amount of lubricating oil is collected, it can be returned to the refrigeration compressor suction port 203 through the oil return pipe 202 or discharged to the outside.

[0026] During the specific operation, slightly open the hot gas pipe valve group FZ-3 to control the hot gas flow entering the heat exchanger 1, then open the oil pipe valve group FZ-1 to adjust the flow of oil entering the heat exchanger 1, check that the frost height on the outer surface of the heat exchanger 1 should not exceed 2 / 3 of the height of the heat exchanger 1, the incoming oil-liquid mixture is heated by the hot gas, the liquid refrigerant becomes gas and returns to the gas-liquid separator through the gas-liquid separator inlet pipe 107, and the oil flows to the oil collector 2 below by gravity, which is the first adjustment. Then further increase the opening degree of the hot gas pipe valve group FZ-3 to check the defrosting condition of the heat exchanger 1 surface. When the surface frosts to the point where the liquid extraction pipe enters the heat exchanger 1, increase the opening degree of the oil extraction pipe valve group FZ-1 and then check the frost condition on the surface of the heat exchanger 1. It should not exceed 2 / 3 of the height of the heat exchanger 1, which is the second adjustment. By adjusting back and forth like this, the required oil separation speed can be adjusted.

[0027] After the separated oil enters the oil collector 2, the liquid level will slowly rise. When it rises to the upper limit of the liquid level controlled by the LS101 liquid level controller, the return oil pipe valve group FZ-4 will be opened to discharge the oil to the suction port of the compressor. When the oil level drops to the lower limit of the liquid level controlled by the LS101 liquid level controller, the return oil pipe valve group FZ-4 will be closed. Before discharging the oil, the opening degree of the return oil pipe valve group FZ-4 needs to be controlled to control the flow of discharged oil entering the compressor to avoid causing wet stroke of the screw compressor.

[0028] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0029] The above-mentioned embodiments only express several implementation methods of the utility model, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the utility model. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the utility model, and these all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A system for separating lubricating oil on the low-pressure side of a refrigeration system by heat exchange of working fluid, comprising a heat exchanger (1) and an oil collector (2) arranged vertically, characterized in that: An oil collecting pipe (3) is provided between the bottom of the heat exchanger (1) and the top of the oil collector (2); The top of the heat exchanger (1) is connected to an oil extraction pipe (101), an oil extraction pipe valve group FZ-1 (102) is provided on the oil extraction pipe (101), the left side of the heat exchanger (1) is connected to a hot gas pipeline (103), a hot gas pipeline valve group FZ-3 (104) is provided on the hot gas pipeline (103), and the right side of the heat exchanger (1) is connected to a gas-liquid separator air inlet pipe (107); The oil collector (2) is provided with a liquid level controller (201), the bottom of the oil collector (2) is connected to an oil return pipe (202), the output end of the oil return pipe (202) is connected to the compressor suction port (203), and the oil return pipe (202) is provided with an oil return pipe valve group FZ-4 (204).

2. A system for separating lubricating oil on the low-pressure side of a refrigeration system by using working medium heat exchange according to claim 1, characterized in that: A low-pressure balancing pipe (105) is also connected to one side of the top of the heat exchanger (1), and a low-pressure balancing pipe valve group FZ-2 (106) is arranged on the low-pressure balancing pipe (105).

3. A system for separating lubricating oil on the low-pressure side of a refrigeration system by using working medium heat exchange according to claim 1, characterized in that: The bottom of the oil collector (2) is connected to a sewage outlet (205).

Images