The core problem of compressor oper
How does the screw compressor match the refrigerating oil correctly
The role of the compressor in the refrigeration system is equivalent to the human heart. With the development of the market, screw compressors have gradually become the leader of refrigeration compressor products and are used in various cold chains, refrigeration and cold storage. As the screw compressor is a high-speed rotating mechanical equipment, although theoretically speaking, there will be no friction during the operation of the screw compressor, but this theory is established when the relevant refrigerating oil is used correctly. In addition, the refrigerating oil also plays a role in sealing, cooling, and noise reduction. We often encounter compressor failures. The so-called compressor failures are usually because the compressor screw is seized, the bearing is damaged or the motor is burned. Generally speaking, screw seizure or bearing damage accounts for more than 2/3 of compressor failure. The former is mainly due to oil, and the latter is mainly due to electricity. Therefore, refrigerating oil is an important material indispensable for the operation of screw compressors and is the key to determining the service life of the compressor. So do you know how the screw compression should match the refrigeration oil?
Why do screw compressors use refrigerant oil?
Refrigeration oil is an indispensable and important auxiliary material for the operation of screw compressors. Refrigeration oil can form a dynamic seal between the screw and the compression chamber and the male and female screws, reducing the leakage of refrigerant from the high pressure side to the low pressure side during the compression process and reducing mutual interference Mechanical wear; refrigerating oil can cool the compressed refrigerant, the oil is injected into the compressor, absorbing the heat generated by the refrigerant gas in the compression process, and reducing the exhaust temperature; refrigerating oil can lubricate the bearing; refrigerating oil It can transmit the pressure difference force, drive the capacity adjustment system, adjust the position of the capacity adjustment slider through the action of the compressor's loading and unloading solenoid valve, and realize the compressor capacity adjustment control; the refrigerating oil can also reduce the running noise. Therefore, it can be said that the use of screw compressors is good or bad, and in the end, it is mainly focused on the selection and use of oil and the design of system oil return and cooling.
How to choose screw compressor matching refrigeration oil?
If the refrigerating oil is not matched well, it may cause the compressor to burn out, and the impact of the refrigeration system will be immeasurable. The general manager of Lifecome Wu Changlong suggested that the refrigerating oil used in the screw compressor should be the best match of the original factory. High-quality and suitable refrigerating oil can make the screw compressor's cooling capacity higher, and its efficiency is higher.
The application of screw compressors is ever-changing, that is, the working conditions of the compressor are varied, and the oil return of different working fluid systems is different, so the choice of oil is also more complicated. Generally speaking, the working fluid represented by R22 is mostly mineral oil, while the working fluid represented by R404A and R134a is synthetic oil. After the large type is selected, different grades of oil must be selected according to different working conditions.
How to change the refrigerating oil for screw compressors?
Regarding the replacement time of refrigerating oil, it is generally recommended to check or replace the lubricating oil every 10,000 hours of operation of the screw compressor, and after the first operation, it is recommended to replace the lubricating oil and clean or replace the oil filter every 2500 hours. The residue from the system assembly will accumulate in the compressor after the official operation. Therefore, the lubricating oil should be replaced once 2500 hours (or 3 months), and the oil filter element should be replaced at least once if there is no condition. The compressor is like the engine of a car. How often does the car at home be checked, and the oil filter element of the unit's refrigeration system should also be replaced. However, the domestic habit is to keep the compressor running every time it is turned on, as long as the circuit is not broken, and wait for the compressor to be repaired before repairing. However, replacing a small filter element can greatly improve the compressor's wear and tear and maintain energy efficiency. , Improve life.
When replacing the screw compressor for freezing, there are two situations. The first is to replace the refrigerating oil without internal cleaning. The compressor performs a pumping action to recover the system refrigerant to the condenser side (note that the minimum suction pressure of the pumping action is not less than 0.5Kg/cm2G), remove the refrigerant in the compressor, and retain a little internal pressure as a power source to freeze The oil is discharged from the oil drain angle valve of the compressor. The second type is to replace the refrigerating oil and clean the inside. The action of draining the oil is as mentioned above. After the refrigerating oil is drained and the pressure inside and outside the compressor is balanced, loosen the flange bolts with an Allen wrench and remove the oil filter joint After cleaning the hole flange (or oil level switch flange), remove the contaminants in the compressor oil tank, and check whether the oil filter mesh is damaged, and blow off the sludge and contaminants on it. Or replace with a new oil filter, pay attention to tighten the filter interface nut when replacing the new one to make a good seal to prevent internal leakage; the internal gasket of the oil filter connector must be replaced to prevent internal leakage; other flange gaskets are also It is recommended to update.
Precautions for replacing refrigerant oil in screw compressors
Finally, you need to pay attention when replacing the refrigerating oil in the screw compressor. Different brands of refrigerating oil must not be mixed, especially mineral oil and synthetic ester oil. If you replace different brands of refrigerating oil, pay attention to the remaining in the system. Exclude the original refrigerating oil; some oils have hygroscopic properties, so do not expose the refrigerated oil to the air for a long time. During installation, shorten the exposure time as much as possible, and do a good job of vacuuming; if the system has a compressor motor burnout failure, pay special attention to removing the residual acid in the system when replacing the new machine, and after 72 hours of commissioning and operation Check the acidity of the refrigerating oil. It is recommended to replace the refrigerating oil and filter drier to reduce the possibility of acid corrosion. After running for a month or so, check or replace the refrigerating oil again; if the system has had a water ingress accident, pay special attention to removing the water. In addition to replacing the refrigerating oil, pay special attention to the acidity of the oil and replace it in time. Oil and filter drier.
