In an oil-lubricated rotary screw machine, a large amount of oil is injected into the interdental volume of the compressor while the gas is being compressed. The oil-air mixture formed by these oils and compressed gas is discharged into the oil-gas separator of the unit after undergoing the same compression process.
Key Takeaways
- The main root causes and hazards of compressor oil breakdown are as follows:The oil separator core is blocked
- The oil separator core is damagedThe main causes for this breakdown are:
- The oil separator core is burnedSuch failures occur mainly because:
The oil-gas separator is one of the main equipment in the oil-lubricated rotary screw machine unit system. To lower the oil content in the unit exhaust and recycle the lubricant in the unit, the oil-gas separator is used to separate the lubricant from the gas. If the oil component fails, the lubricant cannot be separated well, and the lubricant will be discharged along with the compressed air.
For this reason, the breakdown of oil separation and its oil separation core is the main factor for the high oil consumption breakdown of oil-lubricated screw compressors.
Generally speaking, the oil requirement for oil-lubricated screw compressors is that the residual oil content of the compressed air outlet after oil treatment is not more than 3ppm. Excessive oil content in the air at the compressor outlet is usually referred to as high fuel consumption, also known as oil run.
Table of Contents
- The main root causes and hazards of compressor oil breakdown are as follows:The oil separator core is blocked
- The oil separator core is damagedThe main causes for this breakdown are:
- The oil separator core is burnedSuch failures occur mainly because:
- The separation effect of the oil separation core is poorThe reason for this breakdown is mainly because:
- other reasonsMinimum pressure valve breakdown
- Unqualified compressor lubricant is used
- The design of the oil-gas separation tank is not standardized
- Too much gas
- The oil return check valve is damaged
- Improper setup of oil return pipe
- The air consumption is large.
- The oil return line is blocked
The main root causes and hazards of compressor oil breakdown are as follows:
- The oil separator core is blocked
When the oil separator core is blocked, the compressor motor current will be too large. It is also possible that the oil separator core may be deformed due to excessive pressure, or the main engine may be locked when the motor is seriously overloaded. Furthermore, if the current is too large, the life of the contactor will be shortened or the contact will burn out and cause a major accident.
Generally, the screw compressor has a pressure gauge in front of the filter element. When the pressure difference between the pressure gauge in front of the filter element and the air supply pressure gauge reaches 0.08MPa, the oil separator needs to be replaced.
- The oil separator core is damaged
When the oil separator core is damaged, the oil consumption of the compressor will be very serious, and there will be a lot of oil in the air storage tank and pipeline. In severe cases, the compressor oil will be directly discharged when the air storage tank drain valve is discharged.
(1) The oil separator core was not replaced on time;
(2) The poor quality oil separator core is selected;
(3) During the setup process, it was not operated according to the regulations, such as inserting the oil separation core when installing the oil return pipe, etc.
- The oil separator core is burned
The burning of the oil separator core is not common but happens occasionally during the operation of the compressor. The main output performance is that the filter screen of the oil separation core is partially or completely carbonized, and even the metal shell of the oil separation core is burned.
(1) The quality of compressor oil is poor;
(2) The quality of the oil separator core itself is too poor;
(3) When the oil separator is installed, there is no dependable connection between the oil separator shell and the oil separator barrel and cannot be grounded. When there is static electricity, the oil mist will be ignited and the oil separator will be burned.
- The separation effect of the oil separation core is poor
The main output performance is that the compressed air contains too much oil, which will cause damage to the post-processing equipment and user equipment.
(1) The quality of the oil separator core itself is too poor;
(2) Did not operate according to the regulations during setup.
other causes
In the actual processing process, we found that a large part of the malfunction complaints were not caused by the quality of the oil. So, besides oil quality problems, what other causes can cause oil leakage? In fact, these situations can also cause oil leakage:
- Minimum pressure valve breakdown
The minimum pressure valve is a part to maintain the pressure of the rotary screw machine system.
If there is a leakage point at the seal of the minimum pressure valve or the minimum pressure valve is opened in advance (because the opening pressure of each manufacturer is different, usually the range is 3.5 ~ 5.5kg/cm2 Between), then the time for the machine to establish the pressure of the oil and gas tank at the initial stage of operation will raise.
At this time, the gas oil mist concentration in the low pressure state is high, and the output flow is fast when passing through the oil component. The load of the oil component is increased, and the separation effect is reduced, resulting in high fuel consumption.
Remedy: Overhaul the minimum pressure valve and replace it when necessary.
- Unqualified compressor lubricant is used
At present, general-purpose screw compressors have high-temperature protection, and their tripping temperature is usually around 110-120°C. Nevertheless, some compressors use unqualified lubricant, and different degrees of oil consumption will occur when the exhaust temperature is high. (Based on this, the higher the temperature, the greater the fuel consumption).
The reason is that after the primary separation of the oil and gas barrel at high temperature, some oil droplets can have the same order of magnitude as the gas phase molecules, and the molecular diameter is ≤0.01μm. It is difficult for the oil to capture and separate them, resulting in excessive fuel consumption.
Remedy: Find the cause of the high temperature, solve the problem and lower the temperature, and use good quality rotary screw machine lubricant as much as possible.
- The design of the oil-gas separation tank is not standardized
Some compressor manufacturers, when designing the oil-gas separation tank, the design of the primary separation system is unreasonable, and the primary separation effect is not ideal, so that the concentration of oil mist before entering the oil component is high, the oil component is overloaded, and the processing capacity is insufficient, resulting in excessive oil consumption. high.
Remedy: The manufacturer improves the design to enhance the primary separation effect.
- Too much gas
The amount of refueling exceeds the normal oil level, and part of the oil is taken away with the airflow, resulting in excessive fuel consumption. the
Remedy: After stopping the machine, after the air pressure in the oil and gas barrel is released to zero, open the oil drain valve and drain the oil to the normal oil level.
- The oil return check valve is damaged
If the oil return check valve is damaged (from one-way to two-way), the internal pressure of the oil separator tank will pour a large amount of oil back into the oil separator through the oil return pipe after the power-down.
The next time the machine is running, the oil in the oil separator will not Suck back the machine head in time, causing part of the oil to run out of the compressor with the separated air (this situation is common in machines that are not equipped with an oil circuit stop valve and an one-way valve for the exhaust outlet of the machine head).
Remedy: Check the one-way valve after dismantling it. If there is debris stuck to it, just clean up the debris. If the one-way valve is damaged, replace it with a new one.
- Improper setup of oil return pipe
When replacing, cleaning, and maintaining the compressor, the oil return pipe is not inserted into the bottom of the oil separator (reference: 1-2 mm from the arc center of the bottom of the oil separator is better), so that the separated oil cannot return to the machine head in time, and the accumulated oil will flow with the Compressed air runs out together.
Remedy: stop the machine, and after the pressure release returns to zero, adjust the oil return pipe to a reasonable height (the oil return pipe is 1~2mm away from the bottom of the oil separator, and the oil return pipe with an oblique opening can be inserted into the bottom of the oil separator).
- The air consumption is large.
The overload and low pressure are used (or the oil treatment capacity selected before the machine leaves the production plant is too tightly matched with the air delivery of the machine)
Load low-pressure use means that when the user uses the compressor, the discharge pressure does not reach the rated working pressure of the compressor itself, but it can basically meet the gas consumption requirements of some enterprise users.
Frequently Asked Questions
How often should compressor oil be changed?
Typically every 2,000–4,000 operating hours or every six months, whichever comes first, depending on oil analysis results and operating conditions.
Why does my compressor need regular filter replacement?
Clogged filters restrict airflow, raise energy use, and let contaminants reach the air end. Scheduled replacement keeps output clean and efficient.
What is the best way to track upkeep?
Use a checklist with date, task, parts used, and operator name. Panrui provides a maintenance schedule with every machine.
Get a Quote for Your Application
Tell us your required pressure, air flow, and application, and the Panrui team will recommend the right compressor with a detailed quotation. Contact us or browse the product range to learn more.