(81a) Lube Oil in An Ethylene Refrigeration System

In 2007 following a plant turnaround, surging was experienced in the ethylene refrigeration compressor in a cracking plant which damaged one of the oil seals on the compressor shaft allowing large amounts of oil to enter the process from the oil seal (these are older design ?wet? seals as opposed to newer-design ?dry gas? seals). The compressor was repaired, and as much oil as possible was drained from the refrigeration system. The system was restarted and ran fine until about 1 year later when a power dip shut down the ethylene and propylene refrigeration systems in the plants. The oil trapped in the system flowed into the cryogenic ethylene refrigeration exchangers, preventing production of on-specification products. During attempts to remove the oil, numerous additional problems developed which greatly increased the downtime required to remove the oil. This paper will describe the mechanisms of failure involved and activities taken to remedy the problem. In addition, concepts to reduce the likelihood and severity of this type of problem will be shared.