When the cooling water temperature of the industrial chiller is low, the exhaust gas superheat is not too high, and the refrigerating oil and the refrigerant will not be separated completely, and the mixture will enter the evaporator, resulting in low pressure of the chiller or blockage of the expansion valve, causing the chiller to fail start up. This is the "oil running" phenomenon of the chiller. The phenomenon is as follows:
1. There is no trace of oil in the oil separator, because the refrigerating oil is not in the condenser, but runs into the evaporator through the expansion valve. At this time, the oil will stick to the heat exchange copper tube of the evaporator, causing The evaporation effect of the evaporator is reduced, and at the same time, the internal pressure of the evaporator is low. At the same time, the suction superheat of the compressor is very low or even the refrigerant liquid is directly sucked in, and the compressor discharge temperature is very low. The vicious cycle of the unit caused all the oil to be collected in the evaporator, and the compressor made a huge noise because the oil could not be supplied, and even caused the oil level of the oil separator of the chiller to stop.
2. There is no trace of oil in the oil separator, because the oil ran into the condenser with the exhaust gas. If the water temperature is continuously low, it will cause all the oil to collect in the condenser and cause oil blockage in the expansion valve. , And due to insufficient liquid supply in the evaporator, the pressure began to drop, resulting in a low-pressure alarm and shutdown.
The solution is as follows:
1. When the oil level in the oil separator drops, the chiller is adjusted to manual control mode to limit the compressor load, for example, limit the energy to 50%.
2. Increase the condensing pressure
3. Reduce the low-pressure alarm value and low-pressure shutdown value of the unit to the allowable range to ensure that the chiller is in operation
4. If the oil level is still very low and the pressure in the evaporator is also very low at the same time, it is necessary to consider whether the oil has run into the evaporator. You can use the evaporator sight glass to observe whether there is white foam rolling inside. If there is, it means that the oil has run into the evaporator, otherwise, it may be in the condenser.
5. After the above steps are completed, the industrial chiller will return to normal, and the oil can be collected at this time:
A: The oil is in the evaporator. Then we have to pay attention to the temperature of the chilled water, first reduce its flow appropriately, let the outlet water temperature decrease, and then rapidly increase the flow rate. At this time, the outlet water temperature of the evaporator will rise rapidly, and the water temperature will exceed the saturation temperature of the refrigerant at this moment. , So that the refrigerant boils violently, and the refrigerant oil will be sucked into the compressor along with the tumbling foam of the refrigerant. However, the exhaust temperature still exceeds the separation temperature of the oil and the refrigerant, causing the oil to return to the oil separator and separate. Repeated several times, the oil can all return to the oil separator. But also need to pay attention to the time interval of each adjustment of the water volume, it is best to make the exhaust temperature rise back to the best before adjustment after each adjustment.
B: The oil is in the condenser. Don't pay too much attention to the water temperature at this moment, as long as the chiller can operate normally. At this time, gradually open the expansion valve to the maximum (note: the opening process should not be too fast, to prevent too much liquid supply and damage the copper pipe in the evaporator), wait a few minutes, until the high and low pressure balance of the chiller, at this time A large amount of white foam can be seen through the sight glass of the evaporator, indicating that the oil has entered the evaporator from the condenser. As long as step A is repeated, the oil can be quickly recovered.
