Answer: (1) The function of the thermal control valve. There is a thermal control valve at the front end of the oil cooler. Its function is to adjust the injection temperature to maintain the exhaust temperature above the pressure dew point temperature. When the machine is just started, the lubricating oil temperature is low. At this time, the thermal control valve will automatically open the return circuit, and the oil will enter the machine body without passing through the oil cooler. If the lubricating oil temperature rises above 67℃, the thermal control valve will slowly open and fully open at 72℃. At this time, all the oil will be cooled by the oil cooler before entering the machine body.
(2) The role of the oil cooler. Its role is to cool the high-temperature lubricating oil that does not contain air after separation by the oil-gas barrel. The cooled lubricating oil enters the air compressor again.
(3) The role of the oil filter. The oil filter is a paper filter. Its function is to filter out impurities in the lubricating oil and keep the lubricating oil clean to ensure the safe operation of the rotor and bearings.
(4) The role of the oil-gas separator (oil-gas barrel). The oil-gas separator has two functions: storing lubricating oil and separating oil and gas for the first time.
The oil-gas separator is referred to as the oil-gas barrel. An oil sight glass is installed on the side of the barrel. Before each start-up, ensure that the static lubricating oil in the oil-gas barrel is between the high oil level line and the low oil level line of the oil sight glass. An oil drain valve is installed under the oil barrel. Its role is to store lubricating oil and perform an oil-gas separation on the oil-gas mixture. That is, after the oil-gas mixture is sprayed into the oil-gas barrel, the flow rate is reduced due to the special structure of the oil-gas barrel, so that the oil and gas are separated for the first time.
(5) The role of the oil fine separator. The oil fine separator filter element is made of multiple layers of fine fibers. The mist oil and gas contained in the compressed air can be almost completely filtered out after oil fine separation. This stage is called secondary oil and gas separation. The oil content in the filtered compressed air is less than 3ppm. The oil filtered by the oil fine separator is concentrated in the groove at the bottom, and then flows back to the bearing end of the body through the return oil pipe, which can prevent the filtered lubricating oil from being discharged with the air.
The outlet of the oil fine separator is equipped with a safety valve, a relief valve and a pressure maintaining valve. The compressed air is led out from here and passed to the rear cooler.
(6) The role of the expansion joint. Eliminate the internal stress of the pipeline caused by thermal expansion and the vibration of the unit.
(7) The role of the oil cut-off solenoid valve. It is opened when the machine is started and closed when the machine is stopped. Its function is to prevent the pressurized lubricating oil from entering the main machine when the machine is stopped and to prevent the lubricating oil from spraying out from the main machine inlet. Some models are not designed to install an oil cut-off solenoid valve.
The flow chart of the 55~180kW screw air compressor system is shown in Figure 3-5.
Figure 3-5 55~180kW screw air compressor system flow chart
