Condition of the chiller shaft seal
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Real-world case: A dual-machine, two-stage screw refrigeration compressor operating at -35°C in a facility was experiencing oil leakage from its shaft seals; the leakage rate reached 120 drops per minute before the machine was shut down, which equated to 24 kg of oil lost per day. Due to concerns regarding production efficiency, the machine remained in operation for some time. After it was shut down and the shaft seals were replaced, it was found that the springs had been stuck by sludge, the outer edge of the static ring was damaged, and the O-rings were deformed, while all other components were in good condition.
Consider having the spring away from the medium, or using a spring-sealing structure!
After all, it’s still a matter of equipment lubrication management
Firstly, this is caused by the lubricant being too dirty. On one hand, it is necessary to conduct regular oil analysis on the lubricant; it is advisable to replace the lubricant every 2 years and to clean the lubrication system as well； On the other hand, the selection of seals can be optimized by choosing mechanical seals with spring guards. Finally, I recommend that refrigeration units be maintained on a regular basis, with periodic inspections.
The lubricating oil is too dirty; furthermore, cleaning oil should be applied to the machine seal area. It would be best to have the equipment diagrams available, as this will help to clarify the issues.
This set of mechanical seals is used in screw compressors. It’s not convenient to provide the drawings. As the original poster mentioned, adding cleaning oil raises the question of whether this will have an impact on the entire refrigeration system. Based on actual operating conditions, the main issue is the mixing of various substances into the refrigeration system, which results in acidity and oil contamination within the system. Additionally, proper lubrication management is lacking – there is no regular analysis of the oil quality or replacement of the oil. In short, it’s still a matter of poor management.
Why is the oil system so dirty? Is it working fine mechanically?
There’s no mechanical issue; it’s mainly the leak in the system’s heat exchanger that causes acidity to accumulate throughout the refrigeration system
By cleaning oil, I mean introducing a flushing oil at the mechanical seal so that no dirt accumulates there; by paying attention to the condition of the oil over time, this issue can generally be avoided.
Analyzing oil based on its oil content gives more accurate results