Use and maintenance of scroll compressor
Common oil shortage failures of compressors:
The compressor has been short of oil for a long time-the mechanism and the friction pairs have overheated, resulting in bearing sintering and shaft holding.
How to ensure proper oil quantity:
When the compressor discharges the refrigerant, it also discharges a small amount of refrigerating machine oil. Even if there is only 0.5% oil rate, if the oil cannot be circulated back to the compressor through the system, if 5HP is taken as an example, the circulation volume is about 330kg/h under ARI operating conditions, then the compressor can be used in 50 minutes. All the oil is taken out, and the compressor will burn out in about 2 to 5 hours. Therefore, in order to ensure that the compressor does not run short of oil, we should proceed from the following two aspects:
Ensure that the refrigerant oil discharged from the compressor returns to the compressor;
Reduce the oil rate of the compressor;
How to ensure that the refrigerant oil discharged from the compressor returns to the compressor:
The flow rate of the refrigerant in the suction pipe (about 6m/sec) should be ensured to return the oil to the compressor, but the maximum flow rate should be less than 15m/sec to reduce the pressure drop and flow noise, and the horizontal pipe should also have a flow direction of the refrigerant The downward slope is about 0.8cm/m.
Prevent freezing oil from remaining in the evaporator.
Make sure that the oil return hole of the gas-liquid separator is too large, which will cause wet compression. If it is too small, the oil return will be insufficient, and the stagnation oil will be in the gas-liquid separator.
There should be no parts in the system where oil is retained.
Make sure that there is enough refrigeration oil in the compressor in the case of long piping high drop, usually use the compressor with oil mirror to confirm.
Frequent compressor startup is not conducive to oil return.
How to reduce the oil rate of the compressor:
Ensure that the refrigerant does not dissolve in the refrigerator oil when the machine is shut down (use crankshaft heater);
Avoid over-wet operation, because excessive oiling caused by foaming;
Internally set oil separator device;
The bubbling of oil inside the compressor makes the oil easily carried out of the compressor.
When the piping length is larger than the allowable value, the pressure loss in the piping becomes larger, which reduces the amount of refrigerant in the evaporator, resulting in a decrease in capacity. At the same time, when there is oil stagnation in the piping, the compressor is starved of oil, resulting in compressor failure. When the refrigeration oil in the compressor is insufficient, the refrigeration oil of the same brand as the compressor should be added from the high pressure side.
When the drop exceeds 10m~15m, an oil return elbow should be installed on the side of the trachea.
①Necessity: When the machine is shut down, avoid freezing oil attached to the piping to return to the compressor, causing liquid compression. On the other hand, in order to prevent the poor oil return of the gas pipe, the compressor will run out of oil.
② Set the interval of the oil return bend, and set an oil return bend every 10m.