(1) Water-cooled oil cooler
The water-cooled oil cooler is a horizontal shell and tube heat exchanger, the oil is outside the tube and the water is inside the tube. The tube bundle is fixed on the tube plates at both ends, and there are baffles in the oil cooler cylinder, which can improve the heat exchange between oil and cooling water. The cooling water inlet temperature of the oil cooler should be less than 32°C, and the oil temperature of the unit should be controlled at 40-65°C.
(2) Thermosiphon oil cooler
The structure of the thermosiphon oil cooler is similar to the principle of the water-cooled oil cooler. It is a horizontal shell and tube type, the oil is outside the tube, and the refrigerant is inside the tube. The temperature of the oil after cooling by the thermosyphon oil cooler is generally 10-20°C higher than the condensing temperature.
(3) Liquid spray cooling
In the unit with liquid spray cooling, the high-pressure refrigerant liquid drawn from the condenser or the liquid receiver passes through the filter, throttle valve or high-temperature expansion valve and is sprayed into an intermediate orifice of the compressor to absorb the heat of compression and cool the oil. The effect of temperature.
(4) Air cooling
Air cooling system This cooling method is indirect cooling, which cools the oil in the oil cooler through the ambient air.
2. Oil change method of screw unit
(1) Oil change method
1. Shut down and then cut off the power.
2. Close the suction check stop valve before the compressor and the exhaust check stop valve at the outlet of the oil separator. If the unit is equipped with a liquid injection device and an economizer, the liquid injection solenoid valve and the valve before the air supply port should also be closed. Shut-off valve.
3. Drain the refrigerant from the oil separator vent valve.
4. Drain the oil from several drain plugs at the bottom of the oil separator.
5. Drain the oil in the oil filter. If there is an oil cooler in the unit, the oil in it should also be drained.
6. Clean or replace several filters or filters listed in the maintenance schedule table.
7. Evacuate.
8. Refuel the crew.
9. Open the suction and exhaust check stop valves, open the liquid injection solenoid valve and the stop valve in front of the air supply port.
10. Turn on the power and turn it on.
(2) Replacing the oil filter element and cleaning the coarse oil filter
1. Shut down and then cut off the power.
2. Close the stop valve before the crude oil filter and after the oil filter, and close the check stop valve between the oil outlet of the crude oil filter and the oil injection port of the compressor.
3. Open the oil filling valve on the crude oil filter to balance the pressure in the oil filter with the atmospheric pressure. Slightly loosen the nut on the olein filter flange cover to slowly release the pressure in the olein filter to equilibrium with atmosphere.
4. Remove the flange cover, replace the filter element in the oil filter, and clean the filter screen in the oil filter.
5. Flange cover for oil coarse filter.
6. Fill up the filtered refrigerating machine oil in the olein filter, install the flange cover of the olein filter, open the stop valve before the crude oil filter, use the olein filter to empty it, and open the crude oil filter Check and shut-off valve between the oil injection port of the compressor and shut-off valve after the oil filter.