Oil-injected screw air compressors have many advantages, such as low vibration, low noise, high efficiency, few wearing parts and relatively low operating and management costs, so they are widely used in various industries in my country.
There are many brands of oil-injected screw air compressors in China. But their general structure and operating principles are basically the same.
The entire process of the oil-injected screw compressor consists of the air intake system, the main engine working pressurization process, the oil-gas separation system, the air compressor oil cooling circulation system and the air supply system.
The air intake system consists of an air filter and a butterfly valve (or a check valve). The air from the outside passes through the air filter and the butterfly valve to the air intake of the compressor main engine.
The main engine of the oil-injected screw air compressor consists of a pair of yin and yang rotors and a shell, which is a positive displacement compressor. Because the yin and yang rotors of the oil-injected screw air compressor are both made of metal and cannot operate without oil lubrication, there will be air compressor oil returned from the oil-gas separation cylinder for lubrication. After the air is pressurized by the main engine, it passes through the check valve and enters the oil-gas separation barrel. The check valve plays a vital role in this position. It can prevent the compressed air of the oil-gas separator from flowing back when the air compressor stops, causing the rotor to reverse, thereby causing a large amount of air compressor oil to come out from the air inlet.
The oil-containing air entering the oil-gas separation barrel is separated from the oil and gas after passing through the oil-gas separation filter. About 95% of the oil is left at the bottom of the oil-gas separation barrel. Under the action of the pressure difference between the oil-gas separation barrel and the main engine, the air compressor oil will pass through the temperature control valve, oil cooler, oil filter and oil cut-off solenoid valve and then return to the main engine.
The air and the remaining about 5% of the air compressor oil will pass through the oil-gas separation filter. This small amount of oil will be deposited at the bottom of the oil-gas separation filter and return to the main engine inlet through a relatively small return oil pipe. If the oil return of this pipe is not smooth or blocked, it will cause the air supply to contain too much oil, causing increased fuel consumption. After passing through the minimum pressure valve, the air is cooled by the air cooler and then enters the air storage tank for production use.