Two years on: zero compressor failures.
Above: seawater plate heat exchangers, where the condenser water loop meets the sea.
OFFSHORE · OFF CAPE TOWN, SOUTH AFRICA · 2024
Troubleshooting and controls · Carrier screw chiller, 385 tons · Client anonymized to protect client confidentiality
A 385-ton Carrier screw chiller on an offshore platform had been losing compressors since the platform was built in 2011. The fault was not in the chiller.
01 · The problem
Since the platform was built in 2011, it had been replacing about three compressors a year. There were a number of other issues on the plant as well.
02 · What we found
The automation system had the wrong condenser water setpoint on the seawater heat exchanger. It was driving the chiller below its minimum entering condenser water temperature. Below that point the compressor cannot separate oil properly. The bearings were starved of oil, over and over, until the compressor failed.
03 · What we did
We handed the client a list of recommended changes: the condenser water setpoint first, then the other issues we found on the plant. Their team implemented them.
04 · The result
The setpoint that had been starving the compressor bearings of oil is corrected. Two years on, there has not been a single compressor failure.
Replacing compressors treated the symptom for fifteen years. The cause was one number in the automation system.