A small steam turbine lube reservoir formerly fitted with a gravity settling water removal arrangement was contaminated with water levels reaching 800 ppm. The plant had increased the reservoir temperature in an attempt to dissipate water, which was resulting in higher than OEM recommended bearing temperatures.
We were asked to provide a solution to consistently maintain water levels < 150 ppm on the 500 gallon / 1875 liter lube reservoir and enable the plant to lower the reservoir temperature to reduce excessive bearing temperatures.
A Hy-Pro COT10 was installed and baseline oil analysis showed that the oil visibly cloudy and 788 ppm at the inlet of the coalesce skid. Analysis of the oil sample on the COT10 outlet showed visibly clear oil and 80 ppm. Approximately 6 hours after starting the coalesce skid the oil analyzed on the inlet of the COT10 showed visibly clear oil and 78 ppm. After several months of operation the turbine was taken off line for maintenance and upon start up there was a high ingress of water around the shaft seals which resulted in several gallons of accumulated water discharged by the coalesce skid. Eventually the reservoir temp was lowered and the water levels remained under control below 150 ppm.
There was no auxiliary heat available at this plant to keep the oil warm during downtime so the turbine was traditionally started with a slow rolling manual start. After installing the COT10 with on-board heaters, the reservoir temperature could be maintained keeping the oil warm, clean and dry. This solution eliminated the need for the slow start-up procedure the plant had since grown accustomed.