CN201680645U - Return oil system of flooded screw water chiller - Google Patents

Abstract

The utility model relates to a return oil system of a flooded screw water chiller. The return oil system comprises a screw compressor, an oil separator, a condenser, a throttling mechanism and an evaporator which are sequentially connected in series through a main refrigerating system pipeline, and also comprises a return oil pipeline: a first return oil pipeline connected with the oil separator and the screw compressor, a second return oil pipeline connecting the evaporator, an air pump and the screw compressor in series, a first equalizing pipeline connecting the air inlet of the air pump, a second electromagnetic valve and the screw compressor in series and a second equalizing pipeline connecting the air inlet of the air pump, a first electromagnetic valve and the condenser in series, and in the second return oil pipeline, a one-way valve is connected in series between the evaporator and the air pump. The return oil system has two operating modes; in the first operating mode, the second electromagnetic valve is opened, the first electromagnetic valve is closed, and the lubricating oil in the evaporator is gathered in the air pump; in the second operating mode, the second electromagnetic valve is closed, the first electromagnetic valve is opened, and the lubricating oil in the air pump is pressed into the screw compressor via the second return oil pipeline.

Description

Screw flooded chiller oil return system

technical field

The utility model belongs to the field of refrigeration equipment, in particular to an oil return system used on a large-scale screw flooded water chiller.

Background technique

The development of large-scale screw flooded chillers is a hot spot in the technical field of large-scale chillers. Compared with traditional dry chillers, flooded chillers have large unit capacity, small evaporation side pressure loss, high energy efficiency ratio, easy cleaning and energy saving. And other advantages have attracted widespread attention from domestic and foreign manufacturers. But as we all know, screw flooded chillers have been facing a common problem for a long time, that is, the oil return problem of the screw compressor. If the oil return problem of the compressor is not properly solved, the compressor will run without oil, which is very easy. cause damage to the compressor. At present, the oil return system of large screw flooded chillers generally uses a combination of oil return on the side of the oil separator and oil return on the side of the evaporator. For the oil return on the evaporator side, two forms are commonly used: the ejector pump oil return system and the oil pump oil return system. For the former, there are currently three main design methods. 1. Using the high-pressure gas on the condensation side as the ejector power source ; 2. Use the high-pressure liquid on the condensing side as the ejection power source; 3. Use the oil returned from the secondary oil as the ejection power source.

The technical problems in the two oil return systems mentioned in the prior art are: 1. For the oil return system of the ejector pump, if the high-pressure gas on the condensing side is used as the ejector power source, when the unit is running at part load , due to the low exhaust pressure, it will cause insufficient injection power, resulting in insufficient oil return of the compressor, and oil loss operation; if the high-pressure liquid on the condensing side is used as the injection power source, it is very easy to cause the compressor to return liquid during oil return, resulting in The compressor is damaged due to liquid hammering, and this method of ejection reduces the condensation efficiency of the condenser to a certain extent; using the oil returned from the secondary oil as the ejection power source has a high ejection ratio, but the separation efficiency of the oil has a great impact on it. The effect of oil return is greatly affected, and the controllability of oil return under different load conditions is poor; 2. Oil pump oil return system, the oil return system is complicated, high in cost, large in number of wearing parts, and noisy in action.

Contents of the invention

The purpose of the utility model is to provide an oil return system of a chiller with sufficient and stable oil return power.

In order to achieve the above purpose, the technical solution adopted by the utility model is: an oil return system of a screw flooded chiller, the oil return system includes a screw compressor connected in series through the main pipeline to form a complete refrigeration cycle, Oil separator, condenser, throttling mechanism, evaporator, the oil return system also includes an oil return pipeline, and the oil return pipeline includes the first connecting the oil separator and the screw compressor The oil return pipeline, the second oil return pipeline for connecting the evaporator, the air pump and the screw compressor in series, the oil return pipeline also includes connecting the air inlet of the air pump and the screw compressor The first balance pipeline, the second balance pipeline connecting the air inlet of the air pump and the condenser, the second solenoid valve is connected in series between the air inlet and the screw compressor , a first solenoid valve is connected in series between the condenser and the air inlet, and a one-way valve is connected in series between the evaporator and the air pump in the second oil return line The oil return system has two working states. In the first working state, the second solenoid valve is opened, the first solenoid valve is closed, and the lubricating oil in the evaporator is collected in the In the air pump mentioned above; in the second working state, the second electromagnetic valve is closed, the first electromagnetic valve is opened, and the lubricating oil in the air pump is pressed into the air pump through the second oil return line In the screw compressor.

Further, a first filter is connected in series between the oil separator and the screw compressor, a second filter is connected in series between the air pump and the screw compressor, and the evaporation A third filter is connected in series between the filter and the one-way valve.

The utility model has the advantages that since the evaporator side adopts a pressure difference air pump oil return system, compared with the commonly used ejector pump oil return system, it has sufficient oil return power, stable oil return when the load changes, and no oil return. Compared with the oil pump oil return system, it has the advantages of simple structure, practicality and low cost, not easy to be damaged, and low noise. Especially when the unit is running at partial load, the mass flow rate decreases, the oil loss decreases, and the condensation pressure as the power source also decreases at the same time. Therefore, this oil return system also has the advantage of automatically adapting the oil return amount according to the working conditions of the unit. , This advantage is not available in other types of oil return systems.

Description of drawings

The attached drawing is a schematic diagram of the working principle of the oil return system of the screw flooded chiller;

Among them: 1. Screw compressor; 2. Oil separator; 3. Condenser; 4. Throttle mechanism; 5. Evaporator; 6. The third filter; 7. One-way valve; 8. Air pump; 9. The first 1. Solenoid valve; 10. Second solenoid valve; 11. First filter; 12. Second filter; 13. Oil return line; 14. Refrigeration system main line; 131. First oil return line; 132. Second Oil return pipeline; 133, first balance pipeline; 134, second balance pipeline; 81, oil inlet; 82, oil return port; 83, air inlet.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is introduced.

As shown in the figure, the utility model discloses an oil return system of a screw flooded water chiller. The oil return system includes a screw compressor 1, an oil separator 2, a condenser 3, and a section connected in series through the main pipeline 14 of the refrigeration system. The flow mechanism 4, the evaporator 5, the screw compressor 1, the oil separator 2, the condenser 3, the throttling mechanism 4, and the evaporator 5 form a complete refrigeration cycle path.

The oil return system also includes an oil return pipeline 13, and the oil return pipeline 13 includes a first oil return pipeline 131 connecting the oil separator 2 and the screw compressor 1, a first oil return pipeline 131 for connecting the evaporator 5, the air pump 8 and the screw compressor 1 in series. The second oil return pipeline 132 , the first balance pipeline 133 connecting the air inlet 83 of the air pump 8 and the screw compressor 1 , and the second balance pipeline 134 connecting the air inlet 83 of the air pump 8 and the condenser 3 . In the above-mentioned first oil return line 131, a first filter 11 is connected in series between the oil separator 2 and the screw compressor 1. After the lubricating oil in the oil separator 2 is filtered, it enters the screw compressor through the first oil return line 131. Machine 1. In the above-mentioned second oil return pipeline 132 , a second filter 12 is connected in series between the air pump 8 and the screw compressor 1 , so that the lubricating oil flowing back through the evaporator 5 side is filtered before entering the screw compressor 1 .

In the first balance pipeline 133, the second solenoid valve 10 is connected in series between the air inlet 83 of the air pump 8 and the screw compressor 1. In the second balance pipeline 134, the condenser 3 and the air inlet 83 is connected in series with the first solenoid valve 9, and in the second oil return line 132, the third filter 6 and the one-way valve 7 are connected in series between the evaporator 5 and the air pump 8. Through the interaction between the first balance pipeline 133 and the second balance pipeline 134 , oil return power is provided for the lubricating oil stored in the air pump 8 , so that it is pressed into the screw compressor 1 .

Specifically, the working principle of the present utility model is:

The lubricating oil enters the oil separator 2 with the exhaust of the screw compressor 1. Under the action of the oil separator 2, the lubricating oil is separated from the high-temperature refrigerant gas and collected at the bottom of the oil separator 2. Due to the oil separator 2 and There is a pressure difference at the suction end of the compressor 1, so the lubricating oil is pressed into the first oil return pipeline 131 between the oil separator 2 and the compressor 1 under the action of the pressure difference, and filtered by the first filter 11 , the lubricating oil returns to the compressor to complete the oil return of the first oil return circuit. A small amount of unseparated lubricating oil circulates with the refrigeration system and flows to the evaporator 5 through the throttling mechanism 4. The refrigerant continues to evaporate in the evaporator 5, and the lubricating oil is gathered at the bottom of the evaporator 5 under low temperature environment and enters the second evaporator. In the secondary oil return circuit, the oil return system has two working states. In the first working state, that is, the normal state, the second solenoid valve 10 is opened, the first solenoid valve 9 is closed, and the suction end of the screw compressor 1 and the evaporator 5 connected, the pressures on both sides are balanced, the lubricating oil in the evaporator 5 flows into the second oil return line 132 under the action of gravity, passes through the third filter 6 and the one-way valve 7, and finally collects in the air pump 8; when the control preset After the time interval, the oil return system switches from the first working state to the second working state. At this time, the solenoid valve 10 is closed, and the solenoid valve 9 is opened. Due to the one-way conductivity of the check valve 7, the evaporator 5 and the The air pump 8 is cut off, and there is a pressure difference between the condenser 3 and the suction end of the compressor 1, so that the lubricating oil in the air pump 8 is forced into the second filter 12, and finally returns to the screw compressor 1 to complete the return process. Oil.

To sum up, the utility model adopts the oil return method combining the secondary oil return circuit of the oil separator and the oil return circuit of the air pump on the evaporator side, so that the lubricating oil of the screw compressor is in the first oil return circuit and the second return circuit. In the oil circuit, the separation and oil return are realized. In the second oil return circuit, the lubricating oil in the evaporator is powered by the pressure difference between the condenser and the screw compressor, and the two solenoid valves operate alternately to realize the differential pressure oil return. Therefore, the oil return system of the present invention has the advantages of reliable operation, stable oil return, simple structure, low cost, and low operating noise.

Claims (4)

1. screw flooded handpiece Water Chilling Units oil return system, described oil return system comprises the helical-lobe compressor (1) that is connected in series and forms complete kind of refrigeration cycle by refrigeration system main line (14) successively, oil eliminator (2), condenser (3), throttle mechanism (4), evaporimeter (5), described oil return system also comprises return line (13), described return line (13) comprises first return line (131) that connects described oil eliminator (2) and described helical-lobe compressor (1), second return line (132) in order to contact described evaporimeter (5) and air pump (8) and helical-lobe compressor (1) is characterized in that:

Described return line (13) also comprises the air inlet (83) of the described air pump of connection (8) and first equalizing line (133) of described helical-lobe compressor (1), connect the air inlet (83) of described air pump (8) and second equalizing line (134) of described condenser (3), be in series with second magnetic valve (10) between described air inlet (83) and the described helical-lobe compressor (1), be in series with first magnetic valve (9) between described condenser (3) and the described air inlet (83), in described second return line (132), be in series with check valve (7) between described evaporimeter (5) and the described air pump (8).

2. screw flooded handpiece Water Chilling Units oil return system according to claim 1 is characterized in that: be in series with first filter (11) between described oil eliminator (2) and the described helical-lobe compressor (1).

3. screw flooded handpiece Water Chilling Units oil return system according to claim 1 is characterized in that: be in series with second filter (12) between described air pump (8) and the described helical-lobe compressor (1).

4. screw flooded handpiece Water Chilling Units oil return system according to claim 1 is characterized in that: be in series with the 3rd filter (6) between described evaporimeter (5) and the described check valve (7).

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