What are the requirements for oil temperature in the control oil of centrifugal compressors?
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An inspection of the oil system of a centrifugal compressor revealed that the control oil for this compressor was led out to the control oil system in front of the oil cooler. And the control oil for compressors that I have seen is drawn from behind the oil cooler, after being cooled down, and then supplied to the control oil system. May I ask if there are any requirements regarding oil temperature for the compressor control oil? Why must this compressor control oil be led out in front of the oil cooler? Please ask an expert for guidance!
In previous oil circuit system designs, the control oil was generally drawn from behind the oil cooler, with the oil temperature maintained within the range of 35–45°C. It is drawn out in front of the oil cooler, with an oil temperature of around 60°C. When the oil temperature of the control oil is maintained at around 60°C, the effect of viscosity on the control oil system is sufficient to meet the requirements. Doing this can reduce energy consumption. You can look it up; there is a paper that provides a quantitative analysis of this design.
There is a requirement: the viscosity of lubricating oil is directly related to temperature. Excessively high temperatures not only cause water loss but also lead to carbon buildup, which affects lubrication.
The parameters for controlling the oil (mainly temperature and pressure) are listed in the equipment’s technical documentation; you can also consult the manufacturer. However, if the control oil is drawn out in front of the oil cooler, there are several issues: 1. Whether there is a separate filter (this is very important); 2. The control of oil temperature cannot be done with precision – only the temperature of the oil tank can be used as a reference, and indoor control systems generally do not have any temperature monitoring capabilities (unless there is a dedicated thermocouple for that oil circuit)
The control oil pipeline is generally thin; it leads away from in front of the oil cooler, probably to prevent freezing, which requires the tank temperature to be kept stable. May I ask whether the control oil is drawn out in front of or behind the oil filter? If it is drawn out in front of the oil filter, care must be taken to prevent mechanical impurities from damaging the control mechanism.
Different manufacturers have different approaches regarding whether to control the oil temperature, but filters are essential in all cases!