How to solve the problem of oil in the air compressor exhaust?

In the compressor failure, the exhaust with oil failure is the most common, the main factors that cause this failure are the following.

Damage to the oil separation core

During the operation of the air compressor, the oil separation core is damaged such as broken and perforated, then it loses the role of oil and gas separation. In other words, the mixed gas and the compressor exhaust pipe are directly connected, then a large amount of cooling oil is not separated out, and it will be discharged from the body together with the gas, which causes the failure of carrying oil in the exhaust process.

Failure of the return line

The oil return line has an important responsibility in the working process of a screw compressor. A pressure difference is formed between the inside of the oil separation core and the inlet of the compressor, and under this pressure difference, the oil return line is responsible for transporting the oil gathered at the bottom of the oil separation core back to the compressor for further use in the next cycle.

If the oil return path is blocked, broken and incorrectly installed and other faults, the oil gathered at the bottom of the oil separation core cannot be transported back to the compressor, causing too much oil to accumulate at the bottom, then this part of the oil that has not been transported back to the compressor will be discharged with the gas, and the phenomenon of oil in the exhaust process will occur.

System pressure control is too low

During operation, the system pressure control is too low, the centrifugal force in the separator is less than the centrifugal force required by the work, and the effect of the separator cannot be fully reflected. As a result, the oil content of the gas in the core of the separator in the next stage is too high, which exceeds its separation range, which also leads to incomplete separation of oil and gas.

Minimum pressure valve failure

The function of the minimum pressure valve is to ensure that the system pressure is controlled above the minimum pressure during operation. If the minimum pressure valve fails, the minimum pressure of the system will not be guaranteed, and the oil return line may not be able to return oil. The oil accumulated at the bottom of the oil separator core will not be able to be returned to the compressor, and will be discharged from the compressor with the compressed gas, resulting in oil-carrying failure during the exhaust process.

Too much cooling oil added to the compressor

Before the compressor is running, too much cooling oil is added, which exceeds the range of the compressor. During the operation of the compressor, due to the high oil level, although the separation system separates the oil and gas, the gas still remains in the gas discharge. The cooling oil will be drawn into the gas and discharged, causing the oil content in the exhaust gas to be too high, resulting in an oil-carrying fault.

Cooling oil quality is not up to standard

Before the compressor is running, unqualified cooling oil is added, or the cooling oil exceeds the applicable time, and the cooling effect cannot be achieved. Then during the operation of the screw compressor, the cooling oil loses its function and cannot cool and separate the oil and gas. Then there will be an oil failure during the exhaust process.

Troubleshooting and troubleshooting steps

When it is found that there is oil in the exhaust of the compressor, there is no need to rush to dismantle the equipment, but to analyze the causes according to the above, and follow the steps from easy to difficult to determine the location of the fault. This can reduce a lot of repair time and manpower.

When the compressor starts normally and the system reaches the rated pressure, slowly open the exhaust gate valve, and the opening should be as small as possible to allow a small amount of gas to be discharged. At this time, use a dry paper towel to face the exhaust air. If the paper towel immediately changes color and has oil droplets, it can be judged that the oil in the exhaust of the compressor exceeds the standard. According to the amount of oil in the exhaust and different time periods, etc., the fault location can be correctly judged.

When the opening of the exhaust gate valve is increased, if the exhaust air is found to be in the form of an uninterrupted thick fog, it indicates that the oil content of the air flow is very large, and then check the oil return of the oil return pipe observation mirror. If the oil return of the oil return pipe observation mirror increases significantly, it is generally because the separator core is damaged or the cooling oil of the separator is added too much; if there is no oil return in the oil return pipe observation mirror, it is generally because the oil return pipe is broken or blocked.

When the opening of the exhaust gate valve is increased, the front part of the exhaust air flow is dense fog, and after a period of time it returns to normal; continue to increase the opening of the exhaust gate valve, open all the exhaust valves, and then observe the system pressure gauge, If the pressure shown on the pressure gauge is lower than the set pressure of the minimum pressure valve, the exhaust valve is still exhausting and the air flow is continuous thick fog. This phenomenon usually occurs because the minimum pressure valve fails.

After the normal shutdown, the automatic vent valve is exhausted. If there is a large amount of oil in the exhaust, it means that the automatic vent valve is damaged.

Common troubleshooting measures

There are various reasons for the failure of oil in the exhaust gas of the screw compressor during operation, and different reasons require different solutions.

Oil separation core damage problem

It is a common phenomenon that the oil separation core is damaged, so the equipment should be checked before the operation of the screw compressor, and the operating procedures should be strictly followed during use, and the equipment should be regularly maintained after use. If the oil separation core is found to be damaged and perforated, it should be replaced in time to ensure the normal operation of the equipment.

There is a problem with the oil return circuit

During the operation of the equipment, if the oil return circuit is blocked, it is necessary to check the pressure drop of the separator. If the pressure drop is no problem, the oil separator core needs to be cleaned. If the oil separator core is broken, it must be replaced timely.

System pressure control is too low

For operators, they should be familiar with the control pressure of the equipment, and when problems are found, the load on the system should be reduced to make the system pressure reach the rated working pressure.

Minimum pressure valve failure problem

In actual operation, if the minimum pressure valve is found to be invalid, it must be replaced, and the work will be carried out after the replacement is completed.

The problem of adding too much cooling oil to the compressor

When adding cooling oil to the compressor, you should first understand the theoretical value of adding cooling oil to the equipment. Generally, it should be controlled below the middle of the oil return pipe observation mirror.

Cooling oil quality problem

The addition of cooling oil should be strictly in accordance with the requirements of equipment for cooling oil, because different equipment has different requirements for cooling oil. After adding, the addition time should be recorded, and when the cooling oil reaches its service life, it should be replaced on time. The quality of the added cooling oil should be strictly controlled to prevent the addition of unqualified cooling oil.

Cautions of Exclusions and Resolutions

In the process of troubleshooting, there are several points that must be paid attention to, otherwise the failure will not be eliminated, but may lead to greater consequences.

If it is judged to be a problem with the oil return pipe, the oil return pipe can be cleaned or re-welded. In this process, attention should be paid to: first, the oil return pipe must be unobstructed, and the inner diameter of the pipe cannot be reduced due to welding; secondly, the installation position of the oil return pipe must be correct, and the gap between the bottom central recess of the separator core and the end of the oil return pipe should be between 3 and 4mm.

If it is judged to be the problem of the separator core, it needs to be replaced with a new separator core. In this process, attention should be paid to: first, carefully check whether the new separator core is deformed or damaged; secondly, clean the joint surface of the separator cylinder and the top cover; Finally, check whether there is a conductor such as metal on the sealing paper pad on the top of the separator core before installation.

If it is judged that there is too much oil in the separator, drain the oil properly. The method of checking the oil level of the separator should be correct. The unit must be placed horizontally. If the unit is tilted too far, the oil level gauge will display inaccurate. The period of inspection should be selected before driving or half an hour after stopping.

Although the screw compressor is a highly reliable model, it does not mean that it does not need maintenance. Whether it is oil in the exhaust gas or other faults, the maintenance work in operation should be strengthened to prevent the occurrence of faults.