Why does the air oil separator catch fire? What are the factors that cause the fire? According to our long-term experience in dealing with air oil separator failures, we have found that most cases of burnt air oil separators occur in the coldest period of every winter, and usually occur in the morning when the machine is just started. Such cases account for more than 75%. The second is the first start-up of the air compressor after it has been shut down for a period of time, or the air oil separator is burned during the first start-up after maintenance of the machine. This type of case accounts for about 20%. Other reasons only account for about 5%.
The causes of various phenomena are analyzed below:
Burning air oil separators in cold weather
There are many air compressors with low flow rates that are not designed with temperature control valves. When the temperature is low in winter, the viscosity of the engine oil becomes thicker and thicker, and the oil flows slowly. When the machine is started again after being stopped for a period of time, most of the oil in the cooler has flowed into the oil drum due to the shutdown. Because there is no bypass oil circuit to supply oil in time when the main engine is rotating, the oil needs to go through the cooler, oil filter, oil cut-off valve, etc. to reach the main engine.
This period of time will be relatively long. The main engine will be in an oil-starved state for a period of time, and the main and auxiliary rotors will Dry friction can easily produce an open flame, which can ignite the air oil separator when sprayed into the oil and gas barrel.
The oil system design is defective or there is no temperature control valve
If the oil system design of the machine is defective or there is no temperature control valve. The air oil separator will be burned when the machine is started for a period of time or after maintenance. Due to defects in the oil circuit design of most air compressors, the oil after shutdown flows back into the oil and gas separation filter barrel. The inside of the cooler and the main engine are in a state of lack of oil and are filled with air. When starting the machine, the main engine needs to evacuate the air filled in it before the oil can enter.
Due to the long pipeline, the oil supply time will be too long. Causing the main engine to spray fire and cause the oil and gas separation filter element to burn. Some operators (mainly novices) did not add oil to the air inlet of the main unit or the oil filter when maintaining the machine. And then started the machine directly after the maintenance, causing malfunctions. This situation is basically the same as the failure situation that occurs when the machine is down for a long time.
There is another situation: a machine with a temperature control valve design but the temperature control valve is short-circuited for some reason. The bypass oil line is sealed, and the oil only flows through the cooler channel, please refer to the previous article.
The main engine does not receive oil injection for cooling and lubrication. Dry friction is formed between the main and auxiliary rotors and the internal cavity and end surface. Sparks are easily generated under high-speed rotation. And enter the oil and gas barrel through the oil and gas common pipe to ignite the oil and gas separation filter material. This situation occurs in a very short period of time. The machine temperature sensor has a delay in sensing temperature. The high temperature trip protection has not responded in time, and the air oil separator has been burned. This problem usually occurs when the machine is started. After the star-delta conversion is completed, the machine starts loading after a few seconds delay.
Due to the failure of the main oil circuit. The engine oil has not yet reached the inside of the compression chamber of the main engine. The fully open intake valve sucks a large amount of air into the main engine. Since there is no oil cooling during compression. The main engine will make a sharp and harsh dry friction sound when running. Sparks generated by dry friction enter the oil and gas barrel, and the high-heat airflow rapidly expands under the action of the open flame. In about 10-20 seconds, the safety valve begins to release fire smoke.
Excessive static electricity causes sparks to burn air oil separators
You need to check the following aspects：
①The machine is not grounded or is grounded but has poor contact?
②Is there continuity between the oil barrel and the ground wire connected to the machine?
③ When installing a built-in air compressor filter and sealed with an asbestos pad. Checking whether the conductive nails on the oil separator barrel and the oil separator asbestos pad are in poor contact or completely insulated.
④Whether the air oil separators has an electrostatic conduction system or whether the electrostatic conduction system is normal.
Foreign matter has entered the air inlet of the air compressor.
Foreign matter enters the air inlet of the air compressor. Such as broken metal particles, impurities or rags, paper, various fibers, etc. After entering the main engine, the friction between the main and auxiliary rotors generates an open flame and enters the oil and gas barrel to ignite the air oil separators and filter material. This situation mainly occurs after installing a new machine or repairing the host. There once was an air compressor manufacturer. Because the paper label of the main engine fell into the inside of the machine head. As a result, during the assembly of the test machine, the main engine emitted flames and incinerated the air oil separators.
There is a problem with the quality of air compressor oil
There are problems with the quality of the air compressor oil. Such as poor oxidation resistance, carbon deposits and gumming. Which remain on various components of the main oil system for a long time, causing the oil system to block.. After these impurities enter the host, they are likely to cause open flames when compressed. Reaching the oil and gas barrel to burn the oil. You should use better quality air compressor oil.
When the machine is running at high temperature. Promptly investigate the cause of the high temperature and lower the temperature to a reasonable value. If there is carbon deposit or gumming in the oil. It is necessary to clean the air compressor oil circuit and related parts in time to remove all impurities. And then replace the oil with better quality and add it to the machine to ensure that the machine will not have similar occurrences again. Fault.
Electrical circuit short circuit
The open flame caused by the short circuit of the electrical circuit ignited the sound insulation cotton of the machine and burned through the air inlet hose. The fire source entered the inside of the air compressor and burned the oil and machine accessories. Such as the pressure maintenance valve, exhaust pipe, cooler, etc., and the entire machine Basic burning beyond recognition.