Answer: In the oil-injected screw air compressor, the lubricating oil contained in the exhaust of the unit is the oil consumption. The oil-gas separator adopts a combination of mechanical method and affinity coalescence method, that is, two-stage separation is adopted to reduce the consumption of lubricating oil.
Generally speaking, there are three commonly used structural forms of oil-gas separators. The oil-gas barrels of different structural forms are shown in Figure 3-8.
Figure 3-8 (a) is the form that most early oil-gas separators adopted. After the oil-gas mixture enters the oil-gas separator from the air compressor, it first hits the baffle wall set in the separator, and is separated by mechanical collision. Then the oil-gas mixture enters the oil fine separator at a lower speed for secondary separation.
Figure 3-8 (b) and Figure 3-8 (c) Both structures use a combination of collision and cyclone separation for primary separation.
In Figure 3-8 (b), the oil-gas mixture enters the oil fine separator tangentially from the bottom, flows through the preset cyclone channel, and is separated by the centrifugal force generated by the rotation. The primary separation effect of this structural form is improved compared with the simple collision method, but there are still some disadvantages: First, due to the addition of the cyclone channel, the height of the oil-gas separator increases; second, the oil-gas mixture directly sweeps over the oil surface, reducing the separation effect; third, because the cyclone channel is generally welded to the middle and lower part of the oil-gas separator, it makes it very difficult to clean the bottom of the oil-gas separator.
The structural form of Figure 3-8 (c) is to set a cylinder between the oil fine separator and the oil-gas separator wall, and the space between the separator wall and the cylinder is used as a cyclone channel. The oil-gas mixture enters the separator tangentially from the top, and is separated once by the centrifugal force formed by the rotation. Since this method has a good separation effect and avoids the shortcomings of the structure of Figure 3-8 (b), it is increasingly widely used.
The lubricating oil separated by the oil fine separator gathers at the bottom of the oil fine separator and needs to be led out through the oil return pipe and discharged to the suction port of the compressor or the inter-tooth volume at a lower pressure.
