If the compressor runs out of oil, it will not only contaminate post-processing equipment, such as dryers and precision filters, but will also affect product quality and cause varying degrees of damage to certain production equipment. Therefore, it is necessary for us to understand the reasons for the high oil consumption of screw compressors and how to deal with them.
Cause of high fuel consumption failure: oil separation failure
In an oil-injected screw compressor, while compressing the gas, a large amount of oil is injected into the inter-tooth volume of the compressor. The oil-gas mixture formed by these oils and the compressed gas is discharged into the oil-gas separator of the unit after undergoing the same compression process. The oil-gas separator is one of the main equipment in the oil-injected screw compressor system. In order to reduce the oil content in the exhaust of the unit and recycle the lubricating oil in the unit, the oil and gas separator must be used to effectively separate the lubricating oil from the gas.
If there is a failure in the oil separation, the lubricating oil cannot be separated well, and the lubricating oil will be discharged along with the compressed air. Therefore, the failure of oil separation and oil separation core is the most important factor causing high oil consumption failure of oil-injected screw compressors.
Generally speaking, the oil content requirement for oil-injected screw compressors is that the residual oil content of the outlet compressed air after oil treatment should not be greater than 3ppm. Excessive oil content in the air at the outlet of the compressor is usually called high oil consumption, also known as oil leakage. It is a headache that has been plaguing manufacturers, sellers and users for a long time.
The main causes and hazards of compressor oil failure are as follows:
1. The oil separator is clogged
When the oil separator core is clogged, it will cause excessive current in the air compressor motor. It is also possible that the oil separator core will be deformed due to excessive pressure, or the main engine will lock up when the motor is overloaded seriously. In addition, excessive current will shorten the life of the contactor or cause the contacts to burn and cause major accidents. Generally, screw air compressors have 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.
2. Oil separator core damaged
When the oil separator core is damaged, the air compressor will consume very serious oil, and there will be a large amount of oil in the gas tank and pipelines. In severe cases, the air compressor oil will be discharged directly when the air tank drain valve is discharged.
The main causes of this failure are:
(1) The oil separator core was not replaced on time;
(2) A poor quality oil separator core was selected;
(3) The procedures were not followed during the installation process, such as the oil separator core being broken when installing the oil return pipe.
3. Oil separator core burnt
The burning of the oil separator core is not common during the operation of the air compressor, but it does happen occasionally. The main manifestation is that the filter screen of the oil separator core is partially or completely carbonized, and even the metal shell of the oil separator core is burned.
This type of failure occurs mainly because:
(1) The air compressor oil is of poor quality;
(2) The quality of the oil separator core itself is too poor;
(3) When installing the oil separator core, there is no reliable connection between the oil separator core shell and the oil separator barrel and cannot be grounded. When there is static electricity
This causes the oil mist to be ignited and burn the oil separator core.
4. The oil core separation effect is poor
The main manifestation is that the compressed air contains too much oil, causing damage to post-processing equipment and user equipment.
The main reasons for this failure are:
(1) The quality of the oil separator core itself is too poor;
(2) The installation was not performed according to the procedures.
Other reasons:
During the actual handling process, we found that a large number of fault complaints were not caused by oil quality problems. So, in addition to oil quality issues, what other reasons can cause oil leakage? actual
These situations can also cause oil leakage:
1, minimum pressure valve failure
The minimum pressure valve is a component that maintains the pressure of the screw compressor system. If there is a leakage point in the seal of the minimum pressure valve or the minimum pressure valve opens in advance (because the opening pressure designed by each manufacturer is different, usually between 3.5 and 5.5kg/cm2), then the time for the machine to establish the oil and gas tank pressure will increase in the early stages of operation. At this time, the concentration of gas and oil mist in the low-pressure state is high, the flow rate is fast when passing through the oil separation, the oil separation load is increased, and the separation effect is reduced, resulting in large oil consumption.
Solution: Check the minimum pressure valve and replace it if necessary.
2, unqualified compressor lubricant used
Commonly used screw compressors have high-temperature protection, typically tripping at around 110–120°C. Some compressors, however, use substandard lubricating oil and experience varying degrees of oil consumption at high discharge temperatures, with higher temperatures causing greater consumption. At high temperatures, after primary separation in the oil-air separator tank, some oil microdroplets can be of the same order of magnitude as gas-phase molecules, with molecular diameters ≤0.01 μm. The oil separator has difficulty capturing and separating them, leading to excessive oil consumption.
Solution: Find the cause of the high temperature, solve the problem to lower the temperature, and use good quality screw compressor lubricating oil as much as possible.
3, oil and gas separation tank design is not standardized
Some compressor manufacturers, when designing the oil and gas separation tank, have unreasonable design of the primary separation system and unsatisfactory primary separation effect, resulting in a high concentration of oil mist before entering the oil separator. The oil separator load is too heavy and the processing capacity is insufficient, resulting in excessive fuel consumption.
Solution: The manufacturer improves the design and improves the effect of primary separation.
4, too much fuel
If the refueling amount exceeds the normal oil level, part of the oil will be carried away by the air flow, resulting in excessive fuel consumption.
Solution: After shutting down, wait until the air pressure in the oil and gas barrel is released to zero, then open the oil drain valve and drain the oil to the normal oil level.
5, the oil return check valve is damaged
If the oil return check valve is damaged (changes from one-way to two-way), the internal pressure in the oil separator tank will pour a large amount of oil back into the oil separator through the oil return pipe after shutdown. The next time the machine is run, the oil inside the oil separator will not be sucked back into the machine head in time, causing part of the oil to flow out of the compressor along with the separated air (this situation is common in machines that are not equipped with an oil line stop valve and a machine head exhaust outlet check valve).
Solution: Check the one-way valve after disassembly. If there is any debris blocking it, just clean it. If the one-way valve is damaged, replace it with a new one.
6, oil return pipe is improperly installed
When replacing, cleaning, and repairing the compressor, the oil return pipe is not inserted to the bottom of the oil separator (reference: 1~2mm from the arc center of the oil separator bottom is better), resulting in the separated oil not being able to return to the machine head in time, and the accumulated oil will run out with the compressed air.
Solution: Stop the machine, wait until the pressure relief returns to zero, and adjust the oil return pipe to a reasonable height (the oil return pipe is located 1~2mm from the bottom of the oil separator, and the inclined oil return pipe can be inserted into the bottom of the oil separator).
7, large air consumption, overload and low pressure use (or the oil processing capacity selected before the machine leaves the factory matches the machine exhaust volume too tightly)
Low-pressure loaded operation means the compressor's discharge pressure does not reach its rated operating pressure, although it may still meet some users' air requirements. For example, additional air-consuming equipment increases demand, preventing compressor output from balancing consumption. If rated discharge pressure is 8kg/cm2 but actual pressure is only 5kg/cm2 or lower, the compressor remains loaded for long periods without reaching its rated pressure, increasing oil consumption.
The reason is that, under the condition that the exhaust volume remains unchanged, the flow rate of the oil-air mixture increases when it passes through the oil separator, and the oil mist concentration is too high, which increases the oil separator load and ultimately leads to high fuel consumption.
Solution: It is recommended to contact the manufacturer and replace it with an oil product that can be used at low pressure.
8, the oil return line is blocked
When the oil return pipeline (including the one-way valve and the oil return filter on the oil return pipe) is blocked by foreign matter, the oil that condenses at the bottom of the oil separation after separation cannot return to the machine head. The condensed oil droplets are blown up by the air flow and are taken away with the separated air. These foreign objects are usually caused by solid impurities dropped during installation.
Solution: Stop the machine, wait until the pressure in the oil drum is released to zero, remove all the pipe fittings of the oil return pipe, and blow out the blocked foreign matter. When installing the built-in oil separator, be sure to clean the oil and gas barrel cover, and pay attention to whether there are solid particles remaining at the bottom of the oil separator core.
(This article comes from the Internet)